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   28583篇
  免费   2954篇
  国内免费   62篇
耳鼻咽喉   329篇
儿科学   952篇
妇产科学   763篇
基础医学   3953篇
口腔科学   478篇
临床医学   3680篇
内科学   5387篇
皮肤病学   498篇
神经病学   3087篇
特种医学   632篇
外国民族医学   1篇
外科学   3233篇
综合类   426篇
一般理论   29篇
预防医学   3600篇
眼科学   350篇
药学   2304篇
中国医学   50篇
肿瘤学   1847篇
  2023年   272篇
  2022年   413篇
  2021年   1021篇
  2020年   625篇
  2019年   940篇
  2018年   1031篇
  2017年   679篇
  2016年   725篇
  2015年   822篇
  2014年   1090篇
  2013年   1361篇
  2012年   2049篇
  2011年   2001篇
  2010年   1089篇
  2009年   939篇
  2008年   1583篇
  2007年   1482篇
  2006年   1344篇
  2005年   1278篇
  2004年   1146篇
  2003年   953篇
  2002年   898篇
  2001年   558篇
  2000年   487篇
  1999年   462篇
  1998年   238篇
  1997年   226篇
  1996年   203篇
  1995年   190篇
  1994年   178篇
  1993年   162篇
  1992年   421篇
  1991年   361篇
  1990年   325篇
  1989年   309篇
  1988年   345篇
  1987年   290篇
  1986年   265篇
  1985年   221篇
  1984年   245篇
  1983年   194篇
  1982年   142篇
  1980年   112篇
  1979年   193篇
  1978年   123篇
  1976年   132篇
  1975年   132篇
  1974年   121篇
  1973年   113篇
  1972年   119篇
排序方式: 共有10000条查询结果,搜索用时 937 毫秒
31.
32.
33.
The cloning of cDNAs that encode functional glutamate receptors makes it possible to produce antibodies that can be used as high-affinity probes for the localization and characterization of these receptors in the mammalian brain. We have made antibodies to different regions of the first cloned member of this family, GluR1, using bacterially overproduced antigen. On Western blots, these antisera detect glycoprotein(s) of 105 kDa present in crude membranes of the hippocampus and cerebellum. The 105-kDa band is associated with postsynaptic densities, and it is observed in cultured cells upon transfection with the GluR1 cDNA. Although glutamate receptors are thought to be the most prevalent excitatory ligand-gated ion channel in the mammalian brain, immunohistochemistry reveals that the receptors recognized by these antisera are localized predominantly in neurons of the cerebellum and some structures of the limbic system, including the hippocampus, the central nucleus of the amygdala, and portions of the septum. This pattern of expression is, in general, consistent with the distribution of GluR1 mRNA as determined by in situ hybridization histochemistry. Our results suggest that glutamate excitatory circuits recognized by these antisera are predominantly found in regions of the limbic system that are reciprocally interconnected.  相似文献   
34.
35.
Symptoms of tobacco withdrawal. A replication and extension   总被引:19,自引:0,他引:19  
Smokers (n = 315) who wished to quit were randomly assigned in a double-blind manner to groups using either nicotine or placebo gum. Self-reported and observed symptoms of tobacco withdrawal were collected before cessation and at follow-ups of 1 to 2 weeks, 1 month, and 6 months. Self-reported and/or observed anger, anxiety, craving, difficulty concentrating, hunger, impatience, and restlessness were the most prominent symptoms of tobacco withdrawal. These symptoms had returned to precessation levels by 1 month except increased weight, hunger, and craving continued for 6 months in many smokers. Nicotine gum decreased most symptoms, including craving and hunger but not weight. Abstinent smokers with more intense withdrawal were not more likely to relapse. Abstinent smokers who gained more weight were less likely to relapse.  相似文献   
36.
1. The action of (1-28) alpha-human atrial natriuretic peptide (ANP) was studied on human isolated resistance arteries. 2. Renal, skeletal muscle, omental and subcutaneous resistance arteries were taken from tissue removed at surgery and isometric tension responses were measured with a myograph. 3. ANP (10(-9)-10(-6) M) relaxed precontracted segments of renal and skeletal muscle arteries in a concentration-dependent manner. ANP failed to relax isolated omental or subcutaneous arteries. 4. The effect of ANP on human isolated resistance arteries varies depending on the site of origin of the artery.  相似文献   
37.
38.
39.
ObjectiveWe examine remission rate probabilities, recovery rates, and residual symptoms across 36 weeks in the Treatment for Adolescents with Depression Study (TADS).MethodThe TADS, a multisite clinical trial, randomized 439 adolescents with major depressive disorder to 12 weeks of treatment with fluoxetine, cognitive–behavioral therapy, their combination, or pill placebo. The pill placebo group, treated openly after week 12, was not included in the subsequent analyses. Treatment differences in remission rates and probabilities of remission over time are compared. Recovery rates in remitters at weeks 12 (acute phase remitters) and 18 (continuation phase remitters) are summarized. We also examined whether residual symptoms at the end of 12 weeks of acute treatment predicted later remission.ResultsAt week 36, the estimated remission rates for intention-to-treat cases were as follows: combination, 60%; fluoxetine, 55%; cognitive–behavioral therapy, 64%; and overall, 60%. Paired comparisons reveal that, at week 24, all active treatments converge on remission outcomes. The recovery rate at week 36 was 65% for acute phase remitters and 71% for continuation phase remitters, with no significant between-treatment differences in recovery rates. Residual symptoms at the end of acute treatment predicted failure to achieve remission at weeks 18 and 36.ConclusionsMost depressed adolescents in all three treatment modalities achieved remission at the end of 9 months of treatment.  相似文献   
40.
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