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   1327017篇
  免费   100660篇
  国内免费   2416篇
耳鼻咽喉   19092篇
儿科学   40089篇
妇产科学   37221篇
基础医学   201815篇
口腔科学   38843篇
临床医学   115968篇
内科学   248072篇
皮肤病学   28061篇
神经病学   102178篇
特种医学   51615篇
外国民族医学   230篇
外科学   205750篇
综合类   32092篇
现状与发展   2篇
一般理论   372篇
预防医学   102926篇
眼科学   31627篇
药学   101567篇
中国医学   2522篇
肿瘤学   70051篇
  2018年   11754篇
  2015年   11733篇
  2014年   16525篇
  2013年   25417篇
  2012年   34308篇
  2011年   36819篇
  2010年   21393篇
  2009年   20117篇
  2008年   34987篇
  2007年   37962篇
  2006年   38005篇
  2005年   37145篇
  2004年   36403篇
  2003年   35030篇
  2002年   34003篇
  2001年   57171篇
  2000年   58624篇
  1999年   49180篇
  1998年   14129篇
  1997年   12720篇
  1996年   12923篇
  1995年   12065篇
  1994年   11517篇
  1992年   40607篇
  1991年   40785篇
  1990年   40462篇
  1989年   39113篇
  1988年   36412篇
  1987年   35988篇
  1986年   34112篇
  1985年   32968篇
  1984年   25120篇
  1983年   21457篇
  1982年   12990篇
  1981年   11998篇
  1980年   11243篇
  1979年   25307篇
  1978年   18328篇
  1977年   15412篇
  1976年   14425篇
  1975年   16012篇
  1974年   19610篇
  1973年   18669篇
  1972年   17954篇
  1971年   16908篇
  1970年   15891篇
  1969年   15362篇
  1968年   14060篇
  1967年   12893篇
  1966年   11784篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
942.
943.

Background  

Long-term survival for combined aortic and mitral valve replacement appears to be determined by the mitral valve prosthesis from our previous studies. This 21-year retrospective study assess long-term outcome and durability of aortic valve replacement (AVR) with either concomitant mitral valve replacement (MVR) or mitral valve repair (MVrep). We consider only a single mechanical prosthesis.  相似文献   
944.
Impaired lymph drainage is an inevitable consequence of any form of surgery that disrupts lymphatics, resulting in a degree of lymphoedema that may vary from subtle to dramatic and although classically involving an entire limb, may be more localised, confined to only a small area such as a skin flap. Infection is a well-recognised complication of lymphoedema. However, not all inflammatory episodes occurring in the setting of lymphatic dysfunction can be clearly attributed to infection as this article demonstrates. Five patients presented over a 5-year period with distinctive erysipelas-like inflammation affecting the breast which occurred several weeks following reduction mammaplasty in four patients and breast reconstruction in one patient. No clinical response was obtained with standard antibiotics. This inflammatory problem may represent a previously unreported complication of breast surgery with an incidence of 4% following reduction mammaplasty. Recent research supports the notion that this type of episode is most likely to be due to a non-infective inflammatory process related to lymphatic dysfunction induced by surgery.  相似文献   
945.
946.
947.
The reaction route (RR) graph approach recently developed by us for complex, non-linear kinetic mechanisms is applied to the hydrogen oxidation and evolution reactions. A corresponding RR graph is constructed and translated into an equivalent electrical circuit network by associating each elementary step with a characteristic resistance for the steady-state case and considering the overall reaction as a power source. It is further shown that the steady-state kinetics of the reaction can be investigated employing the conventional methods of the electrical network theory. Using a set of rate constants for the hydrogen evolution reaction (her) in alkaline solutions from the literature, the dominant RRs are identified and simplified mechanisms and kinetics derived.  相似文献   
948.
949.
BACKGROUND: White spot lesions are observed in nearly 50% of patients undergoing orthodontic treatment. Long-lasting antibacterial properties of orthodontic cements can reduce this phenomenon. METHODS: The antibacterial properties of 4 orthodontic cements were evaluated by direct contact test (DCT) and agar diffusion test (ADT). With the DCT technique, octet specimens of glass ionomer (CX-Plus; Shofu, Kyoto, Japan), reinforced glass ionomer (GC Fuji ORTHO LC; GC Corporation, Tokyo, Japan), and 2 composite (Transbond XT and Transbond Plus; 3M Unitek, Monrovia, Calif) orthodontic cements were placed on the sidewalls of wells of a 96-microtiter plate. Streptococcus mutans cells (ca. 1 x 10(6) ) were placed on the surface of each specimen for 1 hour at 37 degrees C. Then, fresh media was added to each well, and bacterial growth was monitored for 16 hours with a temperature-controlled spectrophotometer. This was repeated on specimens aged in phosphate-buffered saline for 1 day, 1 week, and 1 month. The ADT was performed by placing specimens in wells punched in agar plates. RESULTS: Measurement of the halo in bacterial lawn after 48 hours showed that only the glass ionomer cement (CX-Plus) produced an inhibition zone (1.2 mm around the sample). Results at the DCT showed that only the reinforced glass ionomer cement (GC Fuji ORTHO LC) exhibited potent antibacterial activity, which lasted 1 week and diminished over the next 3 weeks. CONCLUSIONS: The reinforced glass ionomer cement possessed the most potent and long-lasting antibacterial activity.  相似文献   
950.
The sudden appearance of multiple keratoacanthomas in a patient who has sustained a thermal burn is extremely uncommon. This case report describes a sixty-four-year-old man who noted multiple keratoacanthomas within three weeks after being involved in a gasoline explosion. Multiple keratoacanthomas appear to be a rare complication of thermal cutaneous injury in predisposed persons.  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