首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   4255931篇
  免费   354513篇
  国内免费   14073篇
耳鼻咽喉   59608篇
儿科学   136094篇
妇产科学   111754篇
基础医学   653344篇
口腔科学   116207篇
临床医学   397085篇
内科学   768787篇
皮肤病学   107980篇
神经病学   355580篇
特种医学   165011篇
外国民族医学   504篇
外科学   655068篇
综合类   119490篇
现状与发展   58篇
一般理论   2575篇
预防医学   359277篇
眼科学   100439篇
药学   295680篇
  29篇
中国医学   11323篇
肿瘤学   208624篇
  2021年   56690篇
  2020年   37632篇
  2019年   59139篇
  2018年   76832篇
  2017年   59777篇
  2016年   65859篇
  2015年   78830篇
  2014年   114022篇
  2013年   179575篇
  2012年   123003篇
  2011年   128708篇
  2010年   128235篇
  2009年   130316篇
  2008年   114641篇
  2007年   121653篇
  2006年   130654篇
  2005年   125308篇
  2004年   125401篇
  2003年   115677篇
  2002年   104678篇
  2001年   150628篇
  2000年   145172篇
  1999年   135153篇
  1998年   70962篇
  1997年   66885篇
  1996年   65024篇
  1995年   60172篇
  1994年   54086篇
  1993年   50342篇
  1992年   96443篇
  1991年   93039篇
  1990年   89405篇
  1989年   87144篇
  1988年   80320篇
  1987年   78785篇
  1986年   74126篇
  1985年   73250篇
  1984年   61837篇
  1983年   55581篇
  1982年   46112篇
  1981年   43190篇
  1980年   40558篇
  1979年   53246篇
  1978年   44149篇
  1977年   38976篇
  1976年   36367篇
  1975年   36366篇
  1974年   39507篇
  1973年   37753篇
  1972年   35335篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Despite orientation and mobility (O&M) being a significant factor determining quality of life of people with low vision or blindness, there are no gold standard measures or agreement on how to measure O&M performance. In the first part of this systematic review, an inventory of O&M outcome measures used by recent studies to assess the performance of orientation and/or mobility of adults with vision impairment (low vision and blindness) is presented. A wide variety of O&M outcome measures have been implemented in different fields of study, such as epidemiologic research and interventional studies evaluating training, assistive technology, vision rehabilitation and vision restoration. The most frequent aspect of outcome measures is efficiency such as time, distance, speed and percentage of preferred walking speed, followed by obstacle contacts and avoidance, and dis/orientation and veering. Other less commonly used aspects are target identification, safety and social interaction and self-reported outcome measures. Some studies employ sophisticated equipment to capture and analyse O&M performance in a laboratory setting, while others carry out their assessment in real-world indoor or outdoor environments. In the second part of this review, the appropriateness of implementing the identified outcome measures to assess O&M performance in clinical and functional O&M practice is evaluated. Nearly a half of these outcome measures meet all four criteria of face validity (either clinical or functional), responsiveness, reliability and feasibility and have the potential to be implemented in clinical or functional O&M practice. The findings of this review confirm the complicated and dynamic nature of O&M. Multiple measures are required in any evaluation of O&M performance to facilitate holistic assessment of O&M abilities and limitations of each individual.  相似文献   
92.
93.
Introduction: Percutaneous renal mass biopsy has evolved over the last decade with improvements on previous pitfalls including low tissue yield, high non-diagnostic rates, and complications. As understanding of tumor biology and natural history of renal cortical neoplasms has improved, percutaneous renal mass biopsy is poised to have an expanding role in an area characterized by individualized management and refined risk stratification.

Areas covered: This review summarizes the evolution of renal mass biopsy to its current state with respect to outcomes, indications, and clinical guidelines.

Expert opinion: With improved understanding of differential biological potential of renal cortical neoplasms combined with technical improvements in diagnostic yield and accuracy, utilization of renal mass biopsy is becoming an important adjunct to patient care in a broad range of clinical scenarios, including active surveillance, thermal ablation, and use of primary systemic therapy in localized and advanced settings.  相似文献   

94.
95.
96.
97.
98.
MicroRNAs (miRNAs) play important roles in prostate cancer development. However, it remains unclear how individual miRNAs contribute to the initiation and progression of prostate cancer. Here we show that a basal layer‐enriched miRNA is required for prostate tumorigenesis. We identify miR‐205 as the most highly expressed miRNA and enriched in the basal cells of the prostate. Although miR‐205 is not required for normal prostate development and homeostasis, genetic deletion of miR‐205 in a Pten null tumor model significantly compromises tumor progression and does not promote metastasis. In Pten null basal cells, loss of miR‐205 attenuates pAkt levels and promotes cellular senescence. Furthermore, although overexpression of miR‐205 in prostate cancer cells with luminal phenotypes inhibits cell growth in both human and mouse, miR‐205 has a minimal effect on the growth of a normal human prostate cell line. Taken together, we have provided genetic evidence for a requirement of miR‐205 in the progression of Pten null‐induced prostate cancer.  相似文献   
99.
100.
Secondary tricuspid regurgitation (TR) caused by right ventricular enlargement in the setting of left heart disease/pulmonary hypertension has been well described. In contrast, that associated with right atrial enlargement—atrial functional TR (AF‐TR)—remains largely underappreciated. AF‐TR most often occurs in the setting of lone atrial fibrillation, although it is also seen in its absence (idiopathic AF‐TR). Several recent studies have found that the prevalence, hemodynamic significance, and prognosis of AF‐TR are not inconsequential, suggesting increased physician awareness of this novel clinical entity is warranted. This article discusses the pathogenesis, echocardiographic findings, and treatment of this underappreciated cause of secondary TR.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号