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   61358篇
  免费   4986篇
  国内免费   150篇
耳鼻咽喉   734篇
儿科学   1658篇
妇产科学   1064篇
基础医学   8018篇
口腔科学   741篇
临床医学   6657篇
内科学   12242篇
皮肤病学   663篇
神经病学   5720篇
特种医学   2279篇
外国民族医学   3篇
外科学   10686篇
综合类   709篇
现状与发展   1篇
一般理论   67篇
预防医学   5624篇
眼科学   1158篇
药学   4101篇
中国医学   46篇
肿瘤学   4323篇
  2023年   544篇
  2022年   944篇
  2021年   2248篇
  2020年   1204篇
  2019年   1938篇
  2018年   2301篇
  2017年   1645篇
  2016年   1683篇
  2015年   1848篇
  2014年   2644篇
  2013年   3243篇
  2012年   5009篇
  2011年   4992篇
  2010年   2664篇
  2009年   2253篇
  2008年   3601篇
  2007年   3754篇
  2006年   3189篇
  2005年   2947篇
  2004年   2655篇
  2003年   2329篇
  2002年   2034篇
  2001年   700篇
  2000年   676篇
  1999年   621篇
  1998年   450篇
  1997年   363篇
  1996年   289篇
  1995年   288篇
  1994年   241篇
  1993年   217篇
  1992年   463篇
  1991年   444篇
  1990年   446篇
  1989年   386篇
  1988年   409篇
  1987年   402篇
  1986年   350篇
  1985年   329篇
  1984年   295篇
  1983年   248篇
  1982年   162篇
  1979年   232篇
  1978年   188篇
  1977年   153篇
  1976年   162篇
  1975年   164篇
  1974年   172篇
  1973年   192篇
  1972年   156篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
We report a re-do case of severe aortic valve stenosis due to pannus formation 29 years after an aortic Starr-Edwards caged-ball valve implantation. A huge shelf of calcified and thick pannus tissue below the valve had reduced the already small orifice by at least a third in surface area. The explanted Starr-Edwards valve revealed no mechanical or structural failure. Early detection and treatment of pannus outgrowth is essential in order to prevent life-threatening prosthetic valve malfunctions.  相似文献   
82.
83.
Cardiovascular disease (CVD), which includes myocardial infarction(MI), stroke, and peripheral vascular disease, remains the leading cause of death in the United States and in most developed countries. In the United States today, 25% of patients have metabolic syndrome-including those who have had a prior occlusive vascular disease event, those who are having an acute MI or ischemic stroke, and finally, the largest segment of the population,namely those who have not yet experienced a clinical CVD, but whose risks are substantial (10-year risk 10%). This article reviews the totality of evidence for aspirin in the treatment and prevention of CVD and emphasizes its importance as adjunctive therapy for patients with metabolic syndrome.  相似文献   
84.
Resuscitation training for medical students and junior doctors in the United Kingdom and United States was compared using questionnaires sent to medical schools in both countries. A marked deficiency in the provision of cardiopulmonary resuscitation training has been demonstrated in the United Kingdom; however, in the United States, the availability of uniform certifiable teaching is now widespread. Suggestions for the improvement of training in the United Kingdom are expected to increase medical student proficiency in cardiopulmonary resuscitation. The need for training in basic and advanced resuscitation prior to graduation from medical school is stressed.  相似文献   
85.
Thyrotropin releasing hormone (TRH) was administered intravenously to ten patients with Alzheimer's Disease (AD) in a high-dose paradigm, thought to maximize central nervous system effects and potentially produce facilitation of cholinergic function, a known property of the neuropeptide. Acute effects of TRH on behavioral, cognitive and physiologic measures were assessed after patients received 0.1 mg/kg TRH, 0.3 mg/kg TRH and placebo, the higher TRH dose and placebo being given in a randomized, double-blind fashion. Patients showed statistically significant increases in arousal and improvement in affect, as well as a modest improvement in semantic memory, all after receiving the higher TRH dose. Both TRH doses produced transient rises in systolic blood pressure, with no effect on diastolic blood pressure, heart rate or temperature. This study suggests that high-dose TRH can be safely administered to AD patients and is neurobehaviorally active; further studies are needed to determine the extent and mechanism of the cognitive and psychobiological properties of this peptide in AD and other neuropsychiatric disorders.  相似文献   
86.
The effect of long-term (3-week) administration of various antidepressant drugs on the steady-state concentrations of G protein alpha subunits, Gs alpha, Gi alpha, and Go alpha, has been investigated in rat brain using an enzyme-linked immunosorbent assay. Tricyclic antidepressants and clorgyline decreased Gs alpha and, to a lesser extent, Gi alpha in several brain regions, while Go alpha was increased by tricyclics but not clorgyline. We conclude that long-term treatment with antidepressant drugs exerts differential effects on G protein alpha subunits, and that antidepressant efficacy may potentially be based on functional modifications of signal transduction.  相似文献   
87.
88.
Atopy is widely used as a discriminant in selection for employment involving exposure to allergenic substances. The validity of this has been tested in a population with a known burden of what is largely considered to be an IgE mediated disease, laboratory animal allergy. The findings suggest that atopy is insufficiently sensitive and specific for this purpose and that this is probably true for other occupational allergic diseases. The relation between different concepts of atopy--namely, atopy defined by family history, by personal history, and by skin prick tests with common allergens--has also been examined. The subpopulations identified by these criteria differed appreciably. Different concepts of atopy should not be used synonymously as they often are at present.  相似文献   
89.
OBJECTIVE: Screening colonoscopy has been shown to reduce mortality and cancer stage in hereditary nonpolyposis colorectal cancer (HNPCC) individuals. However, the benefit of screening in intermediate risk groups is unknown. The most recent national guidelines have recommended a reduction of screening frequency for the intermediate risk group. Therefore, this study aims to compare the results of colonoscopic screening in HNPCC and intermediate risk groups and assess the effect of the most recent screening protocol recommendations. METHOD: A total of 244 individuals; 108 from HNPCC families (28 mismatch repair gene carriers) and 136 from intermediate risk families were referred for regular colonoscopic screening by the Regional Genetics Service. Findings from 417 colonoscopies performed between 1992 and 2003 were evaluated. RESULTS: A total of three cancers, 39 adenomas and 41 hyperplastic polyps were found in the HNPCC group compared with one cancer, 22 adenomas and 19 hyperplasic polyps in the intermediate risk group. If the recent screening guidelines for the intermediate group were applied, then 89 (44%) fewer colonoscopies would have been performed. Although no cancers would have been missed, six adenomas (mean size = 5.7 mm, range 2-10 mm) with two graded as severely dysplasic and six hyperplastic polyps would not have been detected. CONCLUSION: The detection rate and distribution of adenomas were similar in both groups. If the new colonoscopic screening recommendations for the intermediate risk group had been applied, a small number of significant lesions would have been missed.  相似文献   
90.
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