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   46686篇
  免费   4142篇
  国内免费   82篇
耳鼻咽喉   276篇
儿科学   1741篇
妇产科学   1654篇
基础医学   5893篇
口腔科学   862篇
临床医学   6664篇
内科学   9461篇
皮肤病学   747篇
神经病学   4009篇
特种医学   1137篇
外科学   4632篇
综合类   789篇
一般理论   63篇
预防医学   5982篇
眼科学   704篇
药学   3508篇
中国医学   45篇
肿瘤学   2743篇
  2023年   270篇
  2022年   360篇
  2021年   684篇
  2020年   530篇
  2019年   870篇
  2018年   979篇
  2017年   787篇
  2016年   836篇
  2015年   926篇
  2014年   1302篇
  2013年   1942篇
  2012年   2873篇
  2011年   2884篇
  2010年   1581篇
  2009年   1488篇
  2008年   2473篇
  2007年   2791篇
  2006年   2596篇
  2005年   2631篇
  2004年   2537篇
  2003年   2312篇
  2002年   2241篇
  2001年   958篇
  2000年   977篇
  1999年   867篇
  1998年   545篇
  1997年   433篇
  1996年   409篇
  1995年   435篇
  1994年   382篇
  1993年   349篇
  1992年   634篇
  1991年   638篇
  1990年   631篇
  1989年   613篇
  1988年   547篇
  1987年   560篇
  1986年   513篇
  1985年   497篇
  1984年   456篇
  1983年   361篇
  1982年   316篇
  1981年   263篇
  1980年   237篇
  1979年   335篇
  1978年   332篇
  1977年   238篇
  1975年   228篇
  1974年   228篇
  1972年   232篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
The role of the anesthesia provider requires a high level of awareness and constant vigilance. Literature indicates, however, that the substance abuse rate in certified registered nurse anesthetists (CRNAs) and anesthesiologists has reached staggering levels. The literature also shows that there has been a change in which controlled drugs are being misused. It is imperative that perianesthesia nurses be aware of the current problem and take steps when indicated to protect both providers and patients. This article discusses the current trends of addiction in anesthesia providers, treatment, and reentry, as well as the role of the perianesthesia nurse in recognizing, reporting, and preventing substance abuse.  相似文献   
72.
OBJECTIVE: To determine physical activity patterns in chronic hemodialysis patients with a specific emphasis on the difference between dialysis and nondialysis days. Design A cross-sectional single-center study. SETTING: Vanderbilt University Outpatient Dialysis Unit. PATIENTS: Twenty current chronic hemodialysis patients: 10 male, 10 female; 15 black, 5 white; mean age, 50.1 +/- 9.9 years; height, 164.5 +/- 10.9 cm; weight, 82.5 +/- 15.4 kg; length on dialysis, 57.3 +/- 45.3 months. METHODS: Minute-by-minute physical activity was assessed over a 7-day period using a triaxial accelerometer, which consists of raw numbers or counts calculated by the 3 axes of the accelerometer (PA counts). PA counts were extrapolated on a daily and hourly basis. Physical functioning tests included: sit-to-stand, 6-minute walk, and 1-repetition maximal leg press exercise. Laboratory values for serum concentrations of albumin, prealbumin, C-reactive protein, and cholesterol were also collected. MAIN OUTCOME MEASURE: PA counts. RESULTS: Total PA counts were significantly lower on dialysis days when compared with nondialysis days (128,279 +/- 74,009 versus 168,744 +/- 95,168, respectively, P = .025). The average PA counts during the 4-hour dialysis time period were significantly lower on dialysis days when compared with nondialysis days (3,086 +/- 3,749 versus 11,070 +/- 7,695, respectively, P = .001). At postdialysis hours 1 and 2, PA counts on dialysis days were significantly higher than on nondialysis days (11,410 +/- 5,340 versus 9,082 +/- 6,646, P = .008, and 14,048 +/- 9,728 versus 8,662 +/- 6,433, P = .016, respectively). By postdialysis hour 4, PA counts on dialysis days had significantly decreased when compared with nondialysis days (6,068 +/- 6,268 versus 10,512 +/- 7,420 PA counts, P = .01, respectively). From postdialysis hours 5 to 20, there was no significant difference in PA counts between dialysis and nondialysis days. CONCLUSION: This study shows that physical activity is lower on dialysis days when compared with nondialysis days, and this decrease is caused by the lack of activity during the 4-hour hemodialysis procedure. New behavior modification strategies involving physical activity, both during hemodialysis and on nondialysis days, must be examined in this patient population.  相似文献   
73.
74.
75.
While less emphasis has traditionally been placed on aesthetics in order to focus on successful osseointegration, increased success rates provided by contemporary endosseous root-form dental implants have improved postoperative peri-implant hard and soft tissue structures. The criteria for the evaluation of implant success should, therefore, include lack of pain, mobility, radiolucency, bone loss, infection, or paresthesia, as well as acceptability and stable aesthetics. This article discusses surgical means to preserve or restore hard and soft tissues around dental implants to achieve ideal and predictable outcomes.  相似文献   
76.
77.
78.
79.
Bone marrow stromal cells (MSCs) increase vascular endothelial growth factor (VEGF) expression and promote angiogenesis after stroke. Angiopoietin-1 (Ang1) and its receptor Tie2 mediate vascular integrity and angiogenesis as does VEGF and its receptors. In this study, we tested whether MSC treatment of stroke increases Ang1/Tie2 expression, and whether Ang1/Tie2 with VEGF/ vascular endothelial growth factor receptor 2 (VEGFR2) (Flk1), in combination, induced by MSCs enhances angiogenesis and vascular integrity. Male Wistar rats were subjected to middle cerebral artery occlusion (MCAo) and treated with or without MSCs. Marrow stromal cell treatment significantly decreased blood-brain barrier (BBB) leakage and increased Ang1, Tie2, and occludin (a tight junction protein) expression in the ischemic border compared with MCAo control. To further test the mechanisms of MSC-induced angiogenesis and vascular stabilization, cocultures of MSCs with mouse brain endothelial cells (MBECs) or astrocytes were performed. Supernatant derived from MSCs cocultured with MBECs significantly increased MBEC expression of Ang1/Tie2 and Flk1 compared with MBEC alone. Marrow stromal cells cocultured with astrocytes also significantly increased astrocyte VEGF and Ang1/Tie2 expression compared with astrocyte culture alone. Conditioned media from MSCs alone, and media from cocultures of MSCs with astrocytes or MBECs, all significantly increased capillary tube-like formation of MBEC compared with control Dulbecco's modified Eagle's medium media. Inhibition of Flk1 and/or Ang1 significantly decreased MSC-induced MBEC tube formation. Knockdown of Tie2 expression in MBECs significantly inhibited MSC-induced tube formation. Our data indicate MSC treatment of stroke promotes angiogenesis and vascular stabilization, which is at least partially mediated by VEGF/Flk1 and Ang1/Tie2.  相似文献   
80.
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