Wiener medizinische Wochenschrift最新文献

筛选
英文 中文
A review of rhegmatogenous retinal detachment: past, present and future.
IF 1.1
Wiener medizinische Wochenschrift Pub Date : 2025-04-04 DOI: 10.1007/s10354-025-01085-9
Jessica Xiong, Tuan Tran, Sebastian M Waldstein, Adrian T Fung
{"title":"A review of rhegmatogenous retinal detachment: past, present and future.","authors":"Jessica Xiong, Tuan Tran, Sebastian M Waldstein, Adrian T Fung","doi":"10.1007/s10354-025-01085-9","DOIUrl":"https://doi.org/10.1007/s10354-025-01085-9","url":null,"abstract":"<p><p>Retinal detachments are ophthalmic emergencies given their potential to become a permanently blinding disorder if left untreated. This review will outline the history, pathogenesis, clinical presentation, and current and future management of retinal detachments.</p>","PeriodicalId":23882,"journal":{"name":"Wiener medizinische Wochenschrift","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143781324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Frequency and risk factors of nosocomial infections in a trauma center: a case study from the Beni Suef University Hospital, Egypt. 创伤中心发生院内感染的频率和风险因素:埃及贝尼苏埃夫大学医院的案例研究。
IF 1.1
Wiener medizinische Wochenschrift Pub Date : 2025-04-01 Epub Date: 2024-11-13 DOI: 10.1007/s10354-024-01059-3
Moaz Beni Melhem, Manal M Yasser, Aya I Tagyan, Shimaa S Khaled, M Sayed Mohamed, Dalal Hussien M Alkhalifah, Wael N Hozzein
{"title":"Frequency and risk factors of nosocomial infections in a trauma center: a case study from the Beni Suef University Hospital, Egypt.","authors":"Moaz Beni Melhem, Manal M Yasser, Aya I Tagyan, Shimaa S Khaled, M Sayed Mohamed, Dalal Hussien M Alkhalifah, Wael N Hozzein","doi":"10.1007/s10354-024-01059-3","DOIUrl":"10.1007/s10354-024-01059-3","url":null,"abstract":"<p><strong>Background and objective: </strong>Hospital-acquired infections (HAI) cause a significant risk to patient maintenance and wellbeing, particularly within the specialized environment of a trauma center. This study focuses on investigating the frequency of HAI in a trauma center through a comprehensive surveillance and monitoring system.</p><p><strong>Methods: </strong>This observational study, conducted between January 2023 and June 2023, focused on the 16-bed trauma center. HAI diagnoses were based on the centers for disease control and prevention (CDC) definitions that typically include specific criteria for different types of infections, for example, urinary tract infections, surgical site infections, bloodstream infections, and others.</p><p><strong>Results: </strong>Among the 160 trauma center-admitted patients, 89 were included in the study. 44 patients contracted HAI, resulting in a frequency of 49.4%. The incidence rates (IR) were 21/1000 central venous catheter (CVC) days for catheter-related bloodstream infections (CRBSI), 10/100 urinary catheter days for catheter-associated urinary tract infections (CAUTI), and 34/1000 ventilator days for ventilator-associated pneumonia (VAP).</p><p><strong>Conclusion: </strong>The HAI percentages noticed in the trauma center are comparatively lower than those reported in other developing country hospitals. The incidence of VAP aligns with findings from other studies.</p>","PeriodicalId":23882,"journal":{"name":"Wiener medizinische Wochenschrift","volume":" ","pages":"117-127"},"PeriodicalIF":1.1,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142628906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
[The impact of an emercency form on the place of death of palliative care patients]. [紧急表格对姑息关怀病人死亡地点的影响]。
IF 1.1
Wiener medizinische Wochenschrift Pub Date : 2025-04-01 Epub Date: 2024-11-13 DOI: 10.1007/s10354-024-01058-4
Günter Polt, Gerold Muhri, Anna Theresia Schultz, Erwin Stolz
{"title":"[The impact of an emercency form on the place of death of palliative care patients].","authors":"Günter Polt, Gerold Muhri, Anna Theresia Schultz, Erwin Stolz","doi":"10.1007/s10354-024-01058-4","DOIUrl":"10.1007/s10354-024-01058-4","url":null,"abstract":"&lt;p&gt;&lt;p&gt;A pilot study conducted by our research group in 2019 showed that a decision made in advance about the transfer of palliative care patients documented within the emergency information was associated with the actual place of death, thus realizing the patient's wishes regarding the place of death. There were also details on how the scope, duration, and frequency of home visits by mobile palliative care teams should be designed in order to fulfill patients' wishes regarding the place of death. Systematic reviews point to a discrepancy between preferred and actual places of death and a lack of prospective studies and data to support patients and their caregivers.The current observational study lasted one year, included all mobile palliative care teams for adults working in Styria and collected data from a total of 1425 patients (52.6% men). The median age at the time of death was 78.1 years (IQR = 17.4). 76.9% of the sample were cancer patients. Other diseases included cardiovascular (6.3%), neurological (4.1%) and respiratory diseases (2.3%).The emergency information used in this study was an optimized version of the emergency information used in the 2019 pilot, based on input from all palliative care teams who participated in 2019.A total of 109 patients (7.6%) of the entire sample took part in the intervention (emergency information). Of these, 85 individuals (78.9% of the intervention group) indicated a preference for on-side treatment, i.e., without transfer. Only 8 patients (7.3%) indicated a preference for transfer and 16 (14.7%) did not indicate a preference. Of the 85 patients who did not wish to be transferred, 75 (88.2%) died at home, i.e., in around 9 out of 10 cases the patient's wishes were complied with. In contrast, of the 8 people who requested transfer, only 3 (37.5%) died at home, i.e., the majority (5 or 62.5%) died in hospital or a palliative care unit, indicating that the patient's wishes were complied with in the majority of cases.The preference expressed in the emergency information for on-site treatment and against transfer was associated with a more than five times higher odds (p &lt; 0.001) of actually dying at home. The preference expressed in the emergency information increased the probability of dying at home from 63% in the control group to 89% in the intervention group.There was also a significant difference according to the number of medical contacts, i.e. patients who took part in the intervention and did not wish to be transferred had twice as many contacts with physicians (p = 0.031).The results of the logistic regression model also suggested an influence of age, disease and intensity of care by physicians on the odds of dying at home: Older people and the minority of palliative care patients who did not suffer from cancer had higher odds of dying at home than those with cancer. While there was no correlation between the duration of care and the total number of care contacts, the odds of dying at home increased ","PeriodicalId":23882,"journal":{"name":"Wiener medizinische Wochenschrift","volume":" ","pages":"110-116"},"PeriodicalIF":1.1,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142628883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Two views on criminal behavior.
IF 1.1
Wiener medizinische Wochenschrift Pub Date : 2025-04-01 DOI: 10.1007/s10354-025-01082-y
Ambika Natarajan
{"title":"Two views on criminal behavior.","authors":"Ambika Natarajan","doi":"10.1007/s10354-025-01082-y","DOIUrl":"https://doi.org/10.1007/s10354-025-01082-y","url":null,"abstract":"<p><p>The emergence of Vienna as a leading center of medical criminalistics has increased research on the physiological differences between criminals and normal people. In the second half of the nineteenth century, criminologists sought to explain human immorality and criminal behavior. In this regard, the work of Moriz Benedikt was of particular significance. This paper argues that the gruesome cases of serial killers who targeted maidservants were instrumental in the rise of forensic medicine and criminalistics in Vienna.</p>","PeriodicalId":23882,"journal":{"name":"Wiener medizinische Wochenschrift","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143754800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Pulmonary presentation and coil marcation of dirofilaria lung coin nodes - case report. 双丝酵母菌肺硬币结节的肺部表现和线圈大理石化--病例报告。
IF 1.1
Wiener medizinische Wochenschrift Pub Date : 2025-04-01 Epub Date: 2024-06-05 DOI: 10.1007/s10354-024-01044-w
Tomislav Bečejac, Luka Marcelić, Damir Danolić, Marko Vrančić, Dorian Hiršl, Dubravko Jalšovec
{"title":"Pulmonary presentation and coil marcation of dirofilaria lung coin nodes - case report.","authors":"Tomislav Bečejac, Luka Marcelić, Damir Danolić, Marko Vrančić, Dorian Hiršl, Dubravko Jalšovec","doi":"10.1007/s10354-024-01044-w","DOIUrl":"10.1007/s10354-024-01044-w","url":null,"abstract":"<p><p>Clinicians face significant diagnostic challenges when dealing with nodal lesions of the lung. The majority of lung nodules are benign; however, a significant number can be cancerous. Dirofilaria infestation should also be considered in the differential diagnosis of nodal lung lesions. Most patients with Dirofilaria infestation are asymptomatic. To determine the etiology of nodal lung infiltrations, procedures like radiological imaging, bronchoscopy, endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA), transthoracic biopsy (TTB), tumor markers, nonspecific serological tests, or surgical removal of the lung coin lesions can be performed. Coil marking of the smaller lung lesions under computed tomography (CT) guidance is a helpful tool in determining the position and localization of the nodal lung lesions. Video-assisted thoracoscopic surgery (VATS) or robot-assisted thoracoscopic surgery (RATS) wedge resection is a diagnostic and therapeutic method of choice. No additional treatment of Dirofilaria other than wedge resection of the lung is necessary.</p>","PeriodicalId":23882,"journal":{"name":"Wiener medizinische Wochenschrift","volume":" ","pages":"135-139"},"PeriodicalIF":1.1,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141248703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Frequency distribution of health disorders in primary care-its consistency and meaning for diagnostics and nomenclature. 初级保健中健康疾病的频率分布--其一致性及其对诊断和命名的意义。
IF 1.1
Wiener medizinische Wochenschrift Pub Date : 2025-04-01 Epub Date: 2024-07-22 DOI: 10.1007/s10354-024-01049-5
Waltraud Fink, Otto Kasper, Gustav Kamenski, Sonja Zehetmayer, Dietmar Kleinbichler, Martin Konitzer
{"title":"Frequency distribution of health disorders in primary care-its consistency and meaning for diagnostics and nomenclature.","authors":"Waltraud Fink, Otto Kasper, Gustav Kamenski, Sonja Zehetmayer, Dietmar Kleinbichler, Martin Konitzer","doi":"10.1007/s10354-024-01049-5","DOIUrl":"10.1007/s10354-024-01049-5","url":null,"abstract":"<p><p>RN Braun observed that frequencies of health disorders in general practice are so consistent that he called his discovery \"Case Distribution Law\". Our study compares morbidity data from methodologically similar surveys in primary care practices over a period of fifty years. Frequency ranks were determined for each observation period and the first 150 ranks were compared with Spearman's correlation coefficients. All correlations were consistently positive. Frequency ranks were strikingly similar for surveys carried out at approximately the same time, especially when nomenclatural matching had been carried out before data collection. Ranks were also very similar where clear disease classifications were possible, but less so for non-specific symptoms.The consistency of the distribution of health disorders helps develop diagnostic strategies (diagnostic protocols) and appropriate labeling for non-specific, diagnostically open symptom classifications. According to Braun's considerations, the regularity of case distribution plays an important role in the professionalization of primary care.</p>","PeriodicalId":23882,"journal":{"name":"Wiener medizinische Wochenschrift","volume":" ","pages":"99-109"},"PeriodicalIF":1.1,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11928369/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141735092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Monitoring analysis of the use of biosimilar medicines in the Campania region (southern Italy) to support effective and sustainable care.
IF 1.1
Wiener medizinische Wochenschrift Pub Date : 2025-04-01 Epub Date: 2025-03-05 DOI: 10.1007/s10354-025-01071-1
Francesco Ferrara, Andrea Zovi, Roberto Langella, Maurizio Capuozzo
{"title":"Monitoring analysis of the use of biosimilar medicines in the Campania region (southern Italy) to support effective and sustainable care.","authors":"Francesco Ferrara, Andrea Zovi, Roberto Langella, Maurizio Capuozzo","doi":"10.1007/s10354-025-01071-1","DOIUrl":"10.1007/s10354-025-01071-1","url":null,"abstract":"<p><strong>Background: </strong>Biosimilar drugs offer a valuable opportunity for healthcare systems worldwide, providing significant cost savings and ensuring the same level of effectiveness and safety in the treatment of chronic conditions. These savings can be reinvested into continuous medical innovations.</p><p><strong>Methods: </strong>A search was carried out to assess the use of key biosimilar medications across various therapeutic areas within an Italian health authority that serves a population of over 1 million people. Data on usage, costs, and the number of patients treated were obtained from the company databases. In addition, a comparison with the year 2022 was performed, aiming to identify any increase in the use of biosimilar drugs during 2023.</p><p><strong>Results: </strong>The analysis of 2023 revealed that a large majority of the studied active ingredients are administered as biosimilar medications, with only a few exceptions. Resistance remains in the prescription of adalimumab and etanercept, with spending on the originators of close to 3 million euros.</p><p><strong>Conclusion: </strong>The comparison between 2023 and 2022 highlighted the growing adoption of biosimilar medications. This positive trend suggests the potential for achieving full utilization in the near future. Such a result would significantly benefit the national healthcare system and the public, ensuring a healthcare approach that is both effective and sustainable.</p>","PeriodicalId":23882,"journal":{"name":"Wiener medizinische Wochenschrift","volume":" ","pages":"128-134"},"PeriodicalIF":1.1,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143558217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
A historical view of the development of corneal transplantation: from penetrating keratoplasty to selective transplantation of the finest corneal layers.
IF 1.1
Wiener medizinische Wochenschrift Pub Date : 2025-04-01 DOI: 10.1007/s10354-025-01077-9
Katharina A Heger, Daniel Egger, Gerald Schmidinger, Christian Skorpik, Sebastian M Waldstein, Niklas Pircher
{"title":"A historical view of the development of corneal transplantation: from penetrating keratoplasty to selective transplantation of the finest corneal layers.","authors":"Katharina A Heger, Daniel Egger, Gerald Schmidinger, Christian Skorpik, Sebastian M Waldstein, Niklas Pircher","doi":"10.1007/s10354-025-01077-9","DOIUrl":"https://doi.org/10.1007/s10354-025-01077-9","url":null,"abstract":"<p><p>Replacement of damaged corneal tissue with a clear transplant represents a viable solution for restoring vision in patients with corneal blindness. Among organ transplants, corneal transplantation occupies a unique status due to the cornea's lack of vascularization. This avascular nature makes immune compatibility testing between donor and recipient unnecessary and reduces the risk of transplant rejection, making corneal transplantation the most successful organ transplant procedure worldwide. Over the past century, corneal transplantation has undergone a transformative journey, evolving from full-thickness keratoplasty to highly refined techniques that selectively target individual diseased corneal layers. These modern lamellar approaches aim for faster recovery times and reduced rejection rates. The global demand for corneal graft tissue far exceeds the availability of donor tissue, leading to prolonged waiting times for patients in need of transplantation. Modern therapeutic strategies are expected to support or potentially even replace transplantation of corneal layers in the future.</p>","PeriodicalId":23882,"journal":{"name":"Wiener medizinische Wochenschrift","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143754798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Concealed spontaneous bilateral tubal pregnancy.
IF 1.1
Wiener medizinische Wochenschrift Pub Date : 2025-03-31 DOI: 10.1007/s10354-025-01079-7
Ivan Brlečić, Ana-Meyra Potkonjak, Dubravko Habek
{"title":"Concealed spontaneous bilateral tubal pregnancy.","authors":"Ivan Brlečić, Ana-Meyra Potkonjak, Dubravko Habek","doi":"10.1007/s10354-025-01079-7","DOIUrl":"https://doi.org/10.1007/s10354-025-01079-7","url":null,"abstract":"<p><p>Bilateral tubal pregnancy (BTP), a rare form of ectopic pregnancy, occurs in 1/200,000 pregnancies and typically follows assisted reproductive techniques (ARTs). We report a case of spontaneous BTP in a 34-year-old woman presenting with acute abdomen and no prior history of ART. The diagnosis was established 27 days after initial presentation via transvaginal ultrasonography and elevated beta human chorionic gonadotropin (beta-HCG). Following diagnostic laparoscopy, bilateral salpingectomy was performed. This case highlights the possibility of BTP, emphasizing the need to carefully inspect the contralateral adnexa when treating a \"unilateral\" ectopic pregnancy.</p>","PeriodicalId":23882,"journal":{"name":"Wiener medizinische Wochenschrift","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143754799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Features of RUNX1-mutated patients with chronic myelomonocytic leukemia in a national (ABCMML) and international cohort (cBioPortal).
IF 1.1
Wiener medizinische Wochenschrift Pub Date : 2025-03-26 DOI: 10.1007/s10354-025-01074-y
Sarah Bayat, Klaus Geissler
{"title":"Features of RUNX1-mutated patients with chronic myelomonocytic leukemia in a national (ABCMML) and international cohort (cBioPortal).","authors":"Sarah Bayat, Klaus Geissler","doi":"10.1007/s10354-025-01074-y","DOIUrl":"https://doi.org/10.1007/s10354-025-01074-y","url":null,"abstract":"<p><p>Big data collected in large international cooperations now allow validation of findings from traditional national patient cohorts for proving consistency. In this study, we compared findings in RUNX1-mutated patients of the Austrian biodatabase for chronic myelomonocytic leukemia (ABCMML) with the CMML cohort documented in cBioPortal. In the cBioPortal cohort, RUNX1-mutated patients had significantly inferior survival and AML-free survival as compared to nonmutated patients. In the ABCMML cohort, survival and AML-free survival were numerically shorter in RUNX1-mutated patients than in wildtype patients, but this did not reach significance. Regarding phenotype, in both cohorts, RUNX1-mutated patients had a significantly higher proportion of patients with thrombocytopenia and lower metric values for platelets as compared to wildtype patients. Validation of data, as we have done in this study in CMML patients using two independent cohorts, ensures the quality standards that are required for their use in clinical decision making.</p>","PeriodicalId":23882,"journal":{"name":"Wiener medizinische Wochenschrift","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143731552","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
0
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
相关产品
×
本文献相关产品
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信