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   1246747篇
  免费   91982篇
  国内免费   2963篇
耳鼻咽喉   16745篇
儿科学   43186篇
妇产科学   36336篇
基础医学   183133篇
口腔科学   34374篇
临床医学   111459篇
内科学   239691篇
皮肤病学   28187篇
神经病学   97256篇
特种医学   48301篇
外国民族医学   348篇
外科学   189033篇
综合类   30637篇
现状与发展   1篇
一般理论   530篇
预防医学   95154篇
眼科学   28690篇
药学   90090篇
  3篇
中国医学   2667篇
肿瘤学   65871篇
  2018年   13586篇
  2017年   10424篇
  2016年   11965篇
  2015年   13549篇
  2014年   18288篇
  2013年   28046篇
  2012年   36547篇
  2011年   38805篇
  2010年   23680篇
  2009年   22109篇
  2008年   36185篇
  2007年   38476篇
  2006年   38880篇
  2005年   37335篇
  2004年   36291篇
  2003年   34789篇
  2002年   33456篇
  2001年   57750篇
  2000年   59083篇
  1999年   49547篇
  1998年   13732篇
  1997年   12458篇
  1996年   12337篇
  1995年   11915篇
  1994年   11036篇
  1993年   10323篇
  1992年   39072篇
  1991年   38543篇
  1990年   37866篇
  1989年   36672篇
  1988年   33316篇
  1987年   33328篇
  1986年   31165篇
  1985年   30220篇
  1984年   22497篇
  1983年   19037篇
  1982年   11407篇
  1981年   10232篇
  1979年   20784篇
  1978年   15074篇
  1977年   12691篇
  1976年   11922篇
  1975年   12699篇
  1974年   15308篇
  1973年   14808篇
  1972年   13676篇
  1971年   12761篇
  1970年   11954篇
  1969年   11034篇
  1968年   10261篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
942.
943.
944.
FDA’S Perspectives on Cardiovascular Devices   总被引:1,自引:0,他引:1  
The Food and Drug Administration (FDA) decision process for approving or clearing medical devices is often determined by a review of robust clinical data and extensive preclinical testing of the device. The mission statement for the Center for Devices and Radiological Health (CDRH) is to review the information provided by manufacturers so that it can promote and protect the health of the public by ensuring the safety and effectiveness of medical devices deemed appropriate for human use (Food, Drug & Cosmetic Act, §903(b)(1, 2(C)), December 31, 2004; accessed December 17, 2008 ). For high-risk devices, such as ventricular assist devices (VADs), mechanical heart valves, stents, cardiac resynchronization therapy (CRT) devices, pacemakers, and defibrillators, the determination is based on FDA’s review of extensive preclinical bench and animal testing followed by use of the device in a clinical trial in humans. These clinical trials allow the manufacturer to evaluate a device in the intended use population. FDA reviews the data from the clinical trial to determine if the device performed as predicted and the clinical benefits outweigh the risks. This article reviews the regulatory framework for different marketing applications related to cardiovascular devices and describes the process of obtaining approval to study a cardiovascular device in a U.S. clinical trial.  相似文献   
945.
946.
Several cases of relapsing attacks during which the ear becomes red and patients experience a burning sensation have been reported in the literature. This combination of symptoms has been described as ‘red ear syndrome’ (RES). We report on a 7‐year‐old boy who had episodes of reddening, swelling and a burning sensation in one ear with local hyperthermia persisting for 3 years. The differential diagnosis included RES and erythromelalgia, as isolated auricular variants of erythromelalgia have been described and the symptoms are difficult to distinguish from RES. In this report, we discuss the similarities and differences between RES and erythromelalgia.  相似文献   
947.
Abstract:  In Sweet's syndrome, the essential features are the characteristic morphology of the lesions, their histologic appearance, the dramatic response to corticosteroids and the absence of scarring. We report an 8-month-old infant in whom Sweet's syndrome was diagnosed and who developed acquired cutis laxa in the skin lesions.  相似文献   
948.
The objective of this review is to identify and review publications describing the impact of reduced somatosensation on balance. Based on knowledge of the association between specific somatosensory loss and deterioration of balance, conclusions can be made about role of somatosensation in standing balance.A systematic literature review is presented in which publications from the years 1993 through 2007 were searched in Medline and Embase. Medical Subject Headings (MESH) terms and free text words (related to balance, somatosensory loss, and lower limb) were used to perform the searches. Fifteen articles were selected for detailed review based on predetermined inclusion criteria, and three of the included articles described the effect of experimentally reduced somatosensation on balance in healthy subjects. Ten of the articles described balance in diabetic neuropathy (DN). The last two included articles described balance in Charcot-Marie-Tooth (CMT) disease type 1A (CMT1A) or type 2 (CMT2).The literature indicates that the tactile sensation is reduced in DN, CMT1A, and CMT2 and when the plantar surface of the feet was hypothermically anesthetized. Joint motion sensation seems to be impaired in patients with DN, and passive joint position sensation appears to be reduced in healthy subjects with anesthesia of ankle and foot from prolonged ischemia. This reduced somatosensation seems to have a negative effect on balance in patients with DN and CMT2; however, this appeared not to be the case in patients with CMT1A and in healthy subjects.  相似文献   
949.
We report a case of localized bullous pemphigoid (BP) in a woman patient with primary lymphoedema tarda. There is only one previous case reported of localized pemphigoid in an area of lymphoedema, this being of the cicatricial variant. Slow circulation in the lymphatic vessels, increased capillary permeability with preferential localization of antibodies in the area, and potential cleavage of the epidermal junction due to increased hydrostatic pressure leading to autoimmunity, have all been advocated as possible pathogenic mechanisms. Nevertheless, we consider that the mechanism by which localized pemphigoid arises on lymphoedema remains elusive, based on a previous case of generalized BP sparing an area of postsurgical lymphoedema.  相似文献   
950.
Background Chromium allergy has traditionally been caused by occupational skin contact with cement. In 1983, Danish legislation made the addition of ferrous sulphate compulsory in cement to reduce the water‐soluble chromium content to not more than 2 ppm. An effect from this intervention has previously been demonstrated among Danish construction workers. Objectives To investigate the development of chromium allergy among patients with dermatitis tested between 1985 and 2007 in Denmark. Furthermore, to determine causative exposures in patients with chromium allergy. Patients and methods A retrospective analysis of patch test data was performed (n = 16 228) and charts from patients with chromium allergy were reviewed. Comparisons were made using a χ2 test. Logistic regression analyses were used to test for associations. Results The prevalence of chromium allergy decreased significantly from 3·6% in 1985 to 1% in 1995 (Ptrend < 0·001) but increased to 3·3% in 2007 (Ptrend < 0·001). The frequency of clinically relevant cement exposure decreased significantly among patients with chromium allergy from 12·7% in 1989–1994 to 3·0% (P < 0·01) in 1995–2007, whereas the frequency of relevant leather exposure increased significantly from 24·1% during 1989–1994 to 45·5% during 1995–2007 (P < 0·02). Conclusions Chromium allergy is currently increasing in Denmark due to leather exposure.  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