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   220342篇
  免费   16144篇
  国内免费   765篇
耳鼻咽喉   2387篇
儿科学   5732篇
妇产科学   4671篇
基础医学   28673篇
口腔科学   4621篇
临床医学   20796篇
内科学   46873篇
皮肤病学   3239篇
神经病学   21317篇
特种医学   7296篇
外国民族医学   13篇
外科学   34220篇
综合类   3482篇
现状与发展   2篇
一般理论   293篇
预防医学   20102篇
眼科学   4472篇
药学   15189篇
  1篇
中国医学   409篇
肿瘤学   13463篇
  2023年   924篇
  2022年   1490篇
  2021年   3596篇
  2020年   2241篇
  2019年   3573篇
  2018年   4166篇
  2017年   3387篇
  2016年   3601篇
  2015年   4279篇
  2014年   6325篇
  2013年   9261篇
  2012年   13631篇
  2011年   14812篇
  2010年   8400篇
  2009年   7594篇
  2008年   14053篇
  2007年   14811篇
  2006年   14366篇
  2005年   14819篇
  2004年   14241篇
  2003年   13260篇
  2002年   12760篇
  2001年   2184篇
  2000年   1788篇
  1999年   2345篇
  1998年   2958篇
  1997年   2535篇
  1996年   2311篇
  1995年   2067篇
  1994年   1851篇
  1993年   1736篇
  1992年   1414篇
  1991年   1368篇
  1990年   1253篇
  1989年   1174篇
  1988年   1213篇
  1987年   1206篇
  1986年   1163篇
  1985年   1253篇
  1984年   1616篇
  1983年   1569篇
  1982年   1901篇
  1981年   1705篇
  1980年   1602篇
  1979年   914篇
  1978年   1032篇
  1977年   1011篇
  1976年   892篇
  1975年   745篇
  1974年   731篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
Most herpesviruses of the beta and gamma subfamilies encode homologues of cytokines and chemokine receptor- related G protein-coupled receptors (GPCRs). The roles of these proteins during normal virus replication in the infected host have not been defined in most cases, but the available data and extrapolation from what is known about the properties and functions of their cellular counterparts indicate that they play primary roles in immune evasion or in activating cellular signaling cascades that enhance virus productive replication. Cytokines and chemokine receptors specified by the two human gammaherpesviruses, human herpesvirus 8 (HHV-8) and Epstein-Barr virus (EBV), are the subject of this review. HHV-8 encodes three chemokines, a homologue of interleukin-6, and a CXCR2-related chemokine receptor, while EBV encodes a distinct GPCR and a homologue of interleukin-10. While these viral cytokines and chemokine receptors no doubt contribute to virus biology, their properties indicate that they may also be involved in virus-induced neoplasia. This review discusses the properties, functions, and likely roles of HHV-8 and EBV cytokines and chemokine receptors in relation to both virus biology and virus-associated disease.  相似文献   
55.
56.
Several case reports have implicated Ginkgo biloba in clinically adverse bleeding disorders. Ginkgo biloba has been reported to increase pain-free walking distance among patients with peripheral artery disease (PAD). Standard PAD therapy includes 325 mg/day aspirin. The objective of this study was to examine potential adverse effects of concomitant aspirin and Ginkgo biloba on platelet function. Ginkgo biloba (EGb 761, 300 mg/day) was compared with placebo for effects on measures of platelet aggregation among adults consuming 325 mg/day aspirin in a randomized, double-blind, placebo-controlled, parallel design trial of 4-week duration. Participants were adults, age 69 +/- 10 years, with PAD or risk factors for cardiovascular disease. Outcome measures included platelet function analysis (PFA-100 analyzer) using ADP as an agonist (n = 26 placebo; n = 29 ginkgo), and platelet aggregation using ADP, epinephrine, collagen and ristocetin as agonists (n = 21 placebo; n = 23 ginkgo). Participants kept daily logs of bleeding or bruising episodes. There were no clinically or statistically significant differences between treatment groups for any agonists, for either PFA-100 analysis or platelet aggregation. Reports of bleeding or bruising were infrequent and similar for both study groups. In conclusion, in older adults with PAD or cardiovascular disease risk, a relatively high dose of Ginkgo biloba combined with 325 mg/day daily aspirin did not have a clinically or statistically detectable impact on indices of coagulation examined over 4 weeks, compared with the effect of aspirin alone. No adverse bleeding events were observed, although the trial was limited to a small sample size.  相似文献   
57.
One of the important steps on the road to becoming expert in a motor skill occurs when the individual can perform the movements in a seemingly effortless and automatic fashion. The authors review two lines of investigations, namely, fMRI and mathematically guided studies of the dynamics of skill acquisition, that suggest that this road to automatic involves two steps: (1) an increasing reliance on the self-regulatory aspects of the motor task, and (2) a minimization of the role of mechanisms based on intentionally directed corrective movements. The interplay between these two mechanisms implies that, at a given skill level, performance decreases whenever intention intervenes. The observation that psychological factors may be as important as mechanical repetition for the development of expertise has important implications for the design of neurorehabilitative strategies.  相似文献   
58.
59.
60.
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