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   25438篇
  免费   2548篇
  国内免费   97篇
耳鼻咽喉   226篇
儿科学   737篇
妇产科学   600篇
基础医学   3426篇
口腔科学   617篇
临床医学   3021篇
内科学   5301篇
皮肤病学   385篇
神经病学   2400篇
特种医学   1026篇
外科学   3255篇
综合类   608篇
一般理论   15篇
预防医学   2584篇
眼科学   477篇
药学   2160篇
  1篇
中国医学   32篇
肿瘤学   1212篇
  2021年   361篇
  2019年   358篇
  2018年   414篇
  2017年   332篇
  2016年   322篇
  2015年   382篇
  2014年   531篇
  2013年   782篇
  2012年   1129篇
  2011年   1171篇
  2010年   696篇
  2009年   600篇
  2008年   1014篇
  2007年   1215篇
  2006年   1104篇
  2005年   1147篇
  2004年   1008篇
  2003年   1077篇
  2002年   965篇
  2001年   706篇
  2000年   712篇
  1999年   605篇
  1998年   363篇
  1997年   294篇
  1996年   268篇
  1995年   301篇
  1994年   269篇
  1993年   243篇
  1992年   542篇
  1991年   496篇
  1990年   484篇
  1989年   491篇
  1988年   449篇
  1987年   446篇
  1986年   393篇
  1985年   458篇
  1984年   393篇
  1983年   307篇
  1982年   302篇
  1981年   243篇
  1980年   251篇
  1979年   350篇
  1978年   299篇
  1977年   224篇
  1976年   255篇
  1975年   225篇
  1974年   272篇
  1973年   284篇
  1972年   233篇
  1971年   213篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
Research on physical activity (PA) by level of acculturation in Hispanic children is limited and findings have been mixed. We examined PA participation by primary language used with parents in a representative sample of 4th, 8th, and 11th grade Texas public school students. Mixed-effects regression models were conducted using cross-sectional data from the 2004–2005 School Physical Activity and Nutrition Study (n = 22,049). Self-reported PA was compared among three language-ethnic groups: Spanish-Hispanic (SH) (referent); English-Hispanic (EH); and English-Other (EO). EH and/or EO girls were generally between 1.25 and 2.58 [OR] times more likely to participate in PA across grade levels, with the largest differences found for school sports in 8th grade girls. EH and EO 8th grade boys were 1.71 (CI: 1.40, 2.10) and 2.06 (CI: 1.68, 2.51) times, respectively, more likely to participate in school sports. Findings indicate important disparities in Spanish-speaking Hispanic children’s PA participation.  相似文献   
23.
24.
Popliteal artery aneurysms representing 80% of peripheral artery aneurysms rarely rupture (a reported incidence of 0.1–2.8 %) and second commonest in frequency after aorto-iliac aneurysms. They usually present with pain, swelling, occlusion or distal embolisation and can cause diagnostic difficulties. We report a 78 year old man who was previously admitted to hospital with a pulmonary embolus secondary to deep venous thrombosis. He was heparinized then warfarinised and was readmitted with a ruptured popliteal aneurysm leading to a large pseudo aneurysm formation. The pulmonary embolus had been due to popliteal vein thrombosis and propagation of the clot. A thorough review of literature identified only one previously reported case of ruptured popliteal artery aneurysm and subsequent large pseudo aneurysm formation. We feel it is important to exclude a popliteal aneurysm in a patient with DVT. This may be more common than the published literature suggests.  相似文献   
25.
26.
OBJECTIVE: To identify the possible contribution of electromyogram (EMG) to scalp electroencephalogram (EEG) rhythms at rest and induced or evoked by cognitive tasks. METHODS: Scalp EEG recordings were made on two subjects in presence and absence of complete neuromuscular blockade, sparing the dominant arm. The subjects undertook cognitive tasks in both states to allow direct comparison of electrical recordings. RESULTS: EEG rhythms in the paralysed state differed significantly compared with the unparalysed state, with 10- to 200-fold differences in the power of frequencies above 20 Hz during paralysis. CONCLUSIONS: Most of the scalp EEG recording above 20 Hz is of EMG origin. Previous studies measuring gamma EEG need to be re-evaluated. SIGNIFICANCE: This has a significant impact on measurements of gamma rhythms from the scalp EEG in unparalysed humans. It is to be hoped that signal separation methods will be able to rectify this situation.  相似文献   
27.
28.
A technique for arthrodesis of small joints of the hand is described that uses a tenon to secure apposition that has good intrinsic stability as well as a large surface area of cancellous bony contact. A minimum of postoperative immobilization is required. The tenon arthrodesis method has been employed in 85 joints. The literature shows pseudoarthrosis rates of 0 to 33%. This technique had a 2.3% failure rate that compares favorably with those in other published series.  相似文献   
29.
Plasma mianserin and desmethylmianserin concentrations were measured in 17 clinically depressed elderly patients after a single 30 mg dose of mianserin. The patients then received mianserin 30 mg daily for up to 6 weeks and the plasma concentrations were measured at weekly intervals. The relationship between concentrations of mianserin and desmethylmianserin at steady-state and at 16 and 24 hours after the single test dose was not good enough to be used for prediction of dosage requirements. Reasons for this finding are discussed.  相似文献   
30.
Linear IgA disease (LAD) is a rare acquired autoimmune bullous disorder, characterized by linear deposition of IgA along the dermoepidermal basement membrane zone. The clinical presentation of LAD consists of vesiculobullous lesions affecting the skin and mucosal surfaces. The present case report presents a rare presentation of this vesiculobullous disorder. Although more than 50% of LAD patients present with oral lesions, there are few reported cases of involvement of the mouth as the sole manifestation. A 79-year-old female presented with a sore mouth and erosions affecting the palate. The symptoms resolved following the provision of mycophenolate, an antiproliferative immunosuppressant which has not previously appeared to have been reported in the long-term successful management of linear IgA disease limited to the mouth. We found that mycophenolate is a useful adjunct to the successful treatment of oral linear IgA when the uses of other immunosuppressants are contraindicated.  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