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   12283篇
  免费   1077篇
  国内免费   50篇
耳鼻咽喉   151篇
儿科学   312篇
妇产科学   313篇
基础医学   1543篇
口腔科学   269篇
临床医学   1468篇
内科学   2336篇
皮肤病学   146篇
神经病学   959篇
特种医学   798篇
外国民族医学   2篇
外科学   1559篇
综合类   387篇
一般理论   8篇
预防医学   1373篇
眼科学   170篇
药学   811篇
中国医学   7篇
肿瘤学   798篇
  2021年   164篇
  2020年   118篇
  2019年   188篇
  2018年   211篇
  2017年   158篇
  2016年   151篇
  2015年   171篇
  2014年   301篇
  2013年   412篇
  2012年   560篇
  2011年   597篇
  2010年   306篇
  2009年   276篇
  2008年   463篇
  2007年   558篇
  2006年   521篇
  2005年   530篇
  2004年   466篇
  2003年   455篇
  2002年   448篇
  2001年   429篇
  2000年   406篇
  1999年   330篇
  1998年   147篇
  1997年   110篇
  1996年   114篇
  1995年   144篇
  1994年   112篇
  1993年   109篇
  1992年   314篇
  1991年   273篇
  1990年   267篇
  1989年   281篇
  1988年   213篇
  1987年   203篇
  1986年   207篇
  1985年   217篇
  1984年   169篇
  1983年   129篇
  1982年   110篇
  1981年   98篇
  1979年   197篇
  1978年   150篇
  1977年   112篇
  1975年   96篇
  1974年   133篇
  1973年   108篇
  1972年   94篇
  1971年   95篇
  1970年   99篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
A cross-sectional comparative study was carried out in two chemical manufacturing plants in order to ascertain the effect of an occupational physiotherapy service on absence attributed to sickness. There was no overall effect on total sickness absence rates in this study, but a possible reduction in short-term sickness absence was noted. Changes in management attitudes to absence attributed to sickness at the comparison site caused a significant reduction in short-term absences. It is concluded that physiotherapy in an occupational setting has little effect on sickness absence compared to management attitudes, but the unquantifiable benefits, such as increased employee mobility, better industrial relations and employee morale may be significant benefits, worthy of further study.  相似文献   
42.
43.
44.
Hypertension after cardiac surgery is common and requires accurate control by carefully regulated infusions of drugs such as sodium nitroprusside. A microprocessor-based controller has been designed to close the loop between the blood pressure response and the infusion rate of a hypotensive drug. This system has been refined by computer simulation of the blood pressure response to sodium nitroprusside and by experience gained in using the controller in eleven patients in the early recovery period after cardiac surgery. The controller was able automatically to maintain blood pressure within 10% of a specified value. Provision of sophisticated safety features in automatic drug infusion controllers is essential for patient protection.  相似文献   
45.
Epidermolysis bullosa is a group of dermatologic disorders with varied inheritance patterns having the common manifestation of blister or bulla formation after minor trauma. Sixteen patients with the disease had the following radiographic manifestations: esophageal stricture (16), fecal impaction (six), vaginal stenosis (one), epithelial bridging and fusion of the digits (six), and aspiration changes in the lungs (two). Esophageal strictures involved the pharynx or cervical esophagus in eight cases and were multiple in five; they ranged in length from 2 mm to 15 cm and tended to progress over time. The findings of esophageal stricture, particularly when multiple and involving the proximal esophagus, and/or the presence of distal phalangeal atrophy with soft-tissue webbing suggest the diagnosis of epidermolysis bullosa.  相似文献   
46.
A 73-year-old man with severe chronic obstructive pulmonary disease and cor pulmonale developed an intermittent right bundle branch block (RBBB) during mechanical ventilation. The appearance and disappearance of his RBBB was temporally associated with each positive pressure breath. Intermittent RBBB is a previously undescribed complication of positive pressure ventilation.  相似文献   
47.
48.
49.
Fifty-seven schizophrenic patients were initially assessed after admission to hospital, at which time their parents completed a Camberwell Family Interview, generating "expressed emotion" (EE) scores. Relapse over the next nine months was not predicted by household EE status or by individual EE scales. Multivariate analyses suggested that a poor course after hospitalization was best predicted by a poor course before admission and by living in a one-parent household. High household EE status was a predictor only in one multivariate analysis after course of illness and one-parent household status had been entered, suggesting an interaction effect. We query the causal proposition linking high EE and relapse and suggest instead that a poor illness course may elicit high EE in relatives, particularly in one-parent households, and, thus, may make the principal contribution to the proposed link.  相似文献   
50.
Recently, 2-halogenated deoxyadenosine analogs (F, Cl, and Br) have been shown to have antitumor activity. These analogs are phosphorylated by cells and are believed to exert their cytotoxic action at the nucleoside triphosphate level. In this work the interaction of these nucleoside triphosphate analogs with potential targets, such as DNA polymerase alpha, beta, and gamma, DNA primase, and ribonucleotide reductase was examined in detail. All of these compounds competitively inhibited the incorporation of dAMP into DNA by DNA polymerase alpha, beta, or gamma. F-dATP was able to completely substitute for dATP using DNA polymerase alpha and gamma, but not with DNA polymerase beta. Cl-dATP and Br-dATP substituted poorly for dATP using DNA polymerase alpha and beta. Extension of a 32P-labeled primer by DNA polymerase alpha, beta, or gamma on a single-stranded M13 template showed that these compounds were incorporated into the 3' end of the growing DNA chain and that elongation beyond the incorporated analogs was significantly retarded for Cl-dATP and Br-dATP using either DNA polymerase alpha or beta. DNA primase using poly(dC) as template was inhibited by these compounds at a concentration 4 to 5 times greater than that required for 2-F-araATP. The 2-halogenated dATP analogs were potent inhibitors of ADP reduction by ribonucleotide reductase. In conclusion, the cytotoxic action of 2-Cl-deoxyadenosine and 2-Br-deoxyadenosine may partially be mediated through the mechanism of "self-potentiation," by depression of the deoxynucleoside triphosphate pools due to inhibition of ribonucleotide reductase, which would facilitate their incorporation into DNA and result in the inhibition of DNA synthesis.  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