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   83016篇
  免费   6163篇
  国内免费   259篇
耳鼻咽喉   962篇
儿科学   2107篇
妇产科学   1141篇
基础医学   11263篇
口腔科学   941篇
临床医学   8780篇
内科学   17669篇
皮肤病学   937篇
神经病学   8159篇
特种医学   3208篇
外科学   13384篇
综合类   1011篇
一般理论   92篇
预防医学   6334篇
眼科学   2034篇
药学   5532篇
中国医学   95篇
肿瘤学   5789篇
  2023年   679篇
  2022年   1068篇
  2021年   2487篇
  2020年   1391篇
  2019年   2269篇
  2018年   2589篇
  2017年   1860篇
  2016年   1953篇
  2015年   2273篇
  2014年   3291篇
  2013年   4195篇
  2012年   6688篇
  2011年   6924篇
  2010年   3779篇
  2009年   3324篇
  2008年   5524篇
  2007年   5749篇
  2006年   5350篇
  2005年   5286篇
  2004年   4776篇
  2003年   4380篇
  2002年   3973篇
  2001年   705篇
  2000年   523篇
  1999年   685篇
  1998年   833篇
  1997年   630篇
  1996年   509篇
  1995年   461篇
  1994年   424篇
  1993年   422篇
  1992年   318篇
  1991年   270篇
  1990年   249篇
  1989年   237篇
  1988年   233篇
  1987年   193篇
  1986年   195篇
  1985年   194篇
  1984年   218篇
  1983年   180篇
  1982年   263篇
  1981年   249篇
  1980年   185篇
  1979年   122篇
  1978年   147篇
  1977年   122篇
  1976年   89篇
  1975年   72篇
  1974年   75篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
Myths about heroin abound. They are now the basis of internationaland national policies and of widespread misery. This book tracestheir development and carefully deconstructs them, aiming primarilyto give accurate information—not to  相似文献   
75.
The 5-HT3-receptor antagonist, ondansetron, has been shown to have positive effects in selected in-vivo models of memory impairment and anxiety. The exact mechanisms underlying such bioactivities are unknown. In the present work, an 86Rb efflux bioassay was used to show that ondansetron has a unique ability to block voltage-gated potassium channels in TE671 human neuroblastoma cells. This intrinsic potassium-channel-blocking (KCB) property is relatively weak (IC50 20 (M), but is not shared by other 5-HT3-receptor ligands including zatosetron, MDL 72222, LY 278, 584, zacopride, 1-phenylbiguanide, and ICS 205–930 (tropisetron). Pre-incubation of the target neuroblastoma cells with several 5-HT-receptor ligands including 5-hydroxytryptamine, 8-OH-DPAT, ketanserin, 2-methyl-5-HT, as well as a number of potent 5-HT3 agonists and antagonists and two selective neurotoxins, failed to abolish the KCB action of ondansetron. A preliminary structure-activity relationship analysis indicates that the KCB activity of ondansetron is almost entirely attributable to its structural nucleus, 2,3-dihyro-9-methyl-4(lH)-carbazolone. It is hypothesized that the KCB action of ondansetron is mediated through receptors other than 5-HT3 receptors. The KCB activity of ondansetron may be a significant factor in the in-vivo cognition-enhancing activities of this compound, conceivably due to depolarization of the hippocampal synaptic membranes and a consequent augmentation of neurotransmission.  相似文献   
76.
77.
During an exposure monitoring study, 78 saw maintenance tradesmen were randomly assigned to be interviewed about their exposures using one of two questionnaire formats: open-ended and partly prompted questions about five categories of materials; and detailed prompting about 75 agents. The more open-ended questionnaire elicited fewer exposure responses overall, but more responses about agents not included on the detailed questionnaire. Composite materials and trade name products were more frequently cited as exposures than individual metals or compounds. Validity of responses was ascertained using air measurements (individual metals) or observations of the employees (composite materials). Sums of sensitivities and specificities were very low (near 1.0) for most of the metals for both types of questionnaire. For composite materials, validity improved substantially. Sensitivities with the partly prompted format (0.44–0.85) were always lower than with detailed prompting (0.80–1.00). Specificities were usually, but not always, higher with partial prompting (0.66–0.92) than with detailed prompting (0.18–0.86). Selection of questionnaire format for an epidemiologic study would depend on the likely prevalence of exposure in controls and the effects of trade-offs in sensitivity and specificity.  相似文献   
78.
79.
80.
Parkinson's disease (PD) is a major cause of disability. To date, there have been no large-scale efforts to measure the quality of PD care because of a lack of quality indicators for conducting an explicit review of PD care processes. We present a set of quality indicators for PD care. Based on a structured review of the medical literature, 79 potential indicators were drafted. Through a two-round modified Delphi process, an expert panel of seven movement disorders specialists rated each indicator on criteria of validity, feasibility, impact on outcomes, room for improvement, and overall utility. Seventy-one quality indicators met validity and feasibility thresholds. Applying thresholds for impact on outcomes, room for improvement, and overall utility, a subset of 29 indicators was identified, spanning dopaminergic therapy, assessment of functional status, assessment and treatment of depression, coordination of care, and medication use. Multivariable analysis showed that overall utility ratings were driven by validity and impact on outcomes (P < 0.01). An expert panel can reach consensus on a set of highly rated quality indicators for PD care, which can be used to assess quality of PD care and guide the design of quality improvement projects.  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