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   38154篇
  免费   3897篇
  国内免费   50篇
耳鼻咽喉   521篇
儿科学   1042篇
妇产科学   777篇
基础医学   5474篇
口腔科学   1383篇
临床医学   4422篇
内科学   7566篇
皮肤病学   505篇
神经病学   3095篇
特种医学   1295篇
外国民族医学   2篇
外科学   5014篇
综合类   932篇
一般理论   32篇
预防医学   4019篇
眼科学   1029篇
药学   2912篇
  1篇
中国医学   29篇
肿瘤学   2051篇
  2021年   605篇
  2020年   382篇
  2019年   621篇
  2018年   698篇
  2017年   495篇
  2016年   528篇
  2015年   642篇
  2014年   890篇
  2013年   1332篇
  2012年   1845篇
  2011年   1921篇
  2010年   1023篇
  2009年   987篇
  2008年   1668篇
  2007年   1758篇
  2006年   1639篇
  2005年   1683篇
  2004年   1551篇
  2003年   1442篇
  2002年   1416篇
  2001年   1096篇
  2000年   1155篇
  1999年   1075篇
  1998年   402篇
  1997年   315篇
  1996年   358篇
  1995年   333篇
  1994年   331篇
  1993年   334篇
  1992年   863篇
  1991年   837篇
  1990年   867篇
  1989年   776篇
  1988年   728篇
  1987年   731篇
  1986年   691篇
  1985年   703篇
  1984年   527篇
  1983年   484篇
  1982年   300篇
  1981年   315篇
  1980年   287篇
  1979年   475篇
  1978年   376篇
  1977年   302篇
  1976年   282篇
  1974年   375篇
  1973年   361篇
  1972年   298篇
  1971年   311篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
21.
22.
23.
The purpose of this study was to evaluate a single-session peer-led safer sex intervention, based on the Information-Motivation-Behavioral Skills theoretical model, for college students residing in campus residence halls. Participants (N = 108) were assigned to either an hour long control or 5-module intervention session. Compared to the control condition, the intervention increased participants’ information and women’s subjective norms about preventative behavior. Both the control and intervention sessions increased intentions to perform preventative behaviors (e.g., keep condoms available). These preliminary results suggest that this intervention is promising for increasing constructs associated with safer sexual behavior and could easily be implemented by residence hall staff.  相似文献   
24.
25.
Summary In 1981 generalized anaphylaxis was registered on 166 occasions in Dutch general and academic hospitals. Clinical details of 120 of those patients revealed that in 107 anaphylaxis was either probable (n=90) or possible (n=17), whereas in 13 cases some other reaction than anaphylaxis had occurred. The series of confirmed cases contained 46 men and 61 women, with mean ages of 47 y and 48 y, respectively.There was a complete recovery in 102 patients and two patients died. Hypotension was present in 79 cases (74%), dyspnoea in 34 cases (32%) and a skin reaction, mainly urticaria, erythema or angioedema, was mentioned in 62 cases (58%). Most cases of anaphylaxis were drug-induced (76%), the main causes being the analgesic glafenine and contrast media. Glafenine was mentioned as the cause in 36% of all admissions for drug-induced anaphylaxis. Only 3.7% of cases had been reported to the voluntary reporting scheme of the Netherlands Centre for Monitoring of Adverse Reactions to Drugs.On the basis of reimbursement data, the risk of developing severe anaphylaxis to glafenine was estimated at 11.7–19.3-fold relative to indomethacin, and 13.4–20.2-fold relative to oral penicillins.  相似文献   
26.
27.
In a study of 66 patients with systemic lupus erythematosus (SLE) and 80 controls it was found that the presence of two deficiency (null) alleles of C4 had a significant effect on mean C4 concentrations in serum. In six controls who each had two C4 null alleles the mean C4 concentration in serum was 56% lower than in 43 controls without C4 null alleles; the nadir of the C4 concentration in four patients with SLE with two null alleles was also lower by a mean of 55% than in 32 patients who did not have null alleles. Reduced production of C4 allotypes in subjects with two null alleles may be an important determinant of total C4 concentration in patients with SLE. For optimal interpretation of C4 concentrations in SLE, C4 allotyping appears to be indicated, particularly to identify patients who have two null alleles of C4.  相似文献   
28.
Forty-six patients with cholangitis were randomized to receive therapy with mezlocillin sodium (24 patients) or a combination of ampicillin sodium--gentamicin sulfate (22 patients). The biliary concentration of mezlocillin was 112 times higher than that of ampicillin and 778 times higher than that of gentamicin. The ratio of the concentration in serum or bile over the minimum inhibitory concentration against aerobic gram-negative bacilli (therapeutic index) was higher for mezlocillin than for either ampicillin or gentamicin. Twenty (83%) of 24 patients were cured following mezlocillin therapy compared with 9 (41%) of 22 patients after ampicillin-gentamicin therapy. The 3 patients with superinfection were in the ampicillin-gentamicin arm of the study. Fewer toxic or adverse effects occurred in association with mezlocillin treatment than with ampicillin-gentamicin treatment. Mezlocillin therapy was more effective, less toxic, and less expensive than treatment with ampicillin and gentamicin for patients with cholangitis.  相似文献   
29.
30.
Early post-mortem data suggest that damage to brain serotonin neurones might play a role in some features (e.g., depression) of Parkinson's disease (PD). However, it is not known whether such damage is a typical characteristic of living patients with PD or whether the changes are regionally widespread. To address this question we measured, by positron emission tomography imaging, levels of the brain serotonin transporter (SERT), a marker for serotonin neurones, as inferred from binding of [11C]-3-amino-4-(2-dimethylaminomethyl-phenylsulfanyl)-benzonitrile (DASB), a second generation SERT radioligand, in subcortical and cerebral cortical brain areas of clinically advanced non-depressed (confirmed by structured psychiatric interview) patients with PD. SERT binding levels in PD were lower than those in controls in all examined brain areas, with the changes statistically significant in orbitofrontal cortex (−22%), caudate (−30%), putamen (−26%), and midbrain (−29%). However, only a slight non-significant reduction (−7%) was observed in dorsolateral pre-frontal cortex, an area implicated in major depression. Our imaging data suggests that a modest, regionally widespread loss of brain serotonergic innervation might be a common feature of advanced PD. Further investigation will be required to establish whether SERT binding is more or less decreased in those patients with PD who also have major depressive disorder.  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