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   20202篇
  免费   1787篇
  国内免费   58篇
耳鼻咽喉   237篇
儿科学   595篇
妇产科学   563篇
基础医学   2694篇
口腔科学   411篇
临床医学   2628篇
内科学   3862篇
皮肤病学   302篇
神经病学   1738篇
特种医学   639篇
外国民族医学   1篇
外科学   2560篇
综合类   430篇
一般理论   12篇
预防医学   1899篇
眼科学   413篇
药学   1453篇
中国医学   34篇
肿瘤学   1576篇
  2022年   170篇
  2021年   381篇
  2020年   247篇
  2019年   341篇
  2018年   457篇
  2017年   326篇
  2016年   364篇
  2015年   369篇
  2014年   577篇
  2013年   844篇
  2012年   1128篇
  2011年   1096篇
  2010年   615篇
  2009年   562篇
  2008年   977篇
  2007年   1020篇
  2006年   1027篇
  2005年   986篇
  2004年   877篇
  2003年   837篇
  2002年   787篇
  2001年   608篇
  2000年   572篇
  1999年   502篇
  1998年   216篇
  1997年   185篇
  1996年   166篇
  1995年   160篇
  1994年   154篇
  1993年   129篇
  1992年   370篇
  1991年   327篇
  1990年   344篇
  1989年   295篇
  1988年   313篇
  1987年   295篇
  1986年   290篇
  1985年   256篇
  1984年   213篇
  1983年   217篇
  1982年   143篇
  1981年   148篇
  1980年   118篇
  1979年   217篇
  1978年   157篇
  1977年   118篇
  1976年   133篇
  1975年   138篇
  1974年   156篇
  1973年   111篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
A 23-year-old man sustained an isolated popliteus tendon rupture while pushing a car. The diagnosis was established with the use of arthroscopy, electromyography, and Cybex testing. After the patient failed to respond to conservative therapy, the tendon rupture was surgically repaired. The patient had an uneventful recovery and returned to his preinjury level of athletic activity. Although popliteus tendon tenosynovitis as well as injury to the popliteus in association with other ligamentous knee injuries has been described, neither an isolated popliteus tendon rupture nor an arthroscopic evaluation of a popliteus tendon rupture has been reported.  相似文献   
72.
73.
A method is described for the chemical measurement of calcium oxalate and phosphate crystal formation in urine. The crystals were centrifuged, washed and the oxalate measured by an immobilised oxalate oxidase technique and the phosphate by a standard centrifugal analyser procedure. The methods proved precise and recoveries were good. Calcium oxalate crystal formation after evaporation is time-dependent and this parameter must therefore be standardised. Values for normal urinary calcium oxalate crystal concentration after concentration are given.  相似文献   
74.
75.
76.
BACKGROUND: Abnormalities in the limbic-hypothalamic-pituitary-adrenal (LHPA) axis have been implicated in the pathogenesis of obsessive-compulsive disorder (OCD). To our knowledge, however, no prior study has measured pituitary gland volume in OCD. METHODS: Volumetric magnetic resonance imaging studies were conducted in 31 psychotropic drug-na?ve children (10 boys, 21 girls) aged 8-17 years and 31 case-matched healthy comparison subjects. RESULTS: Pituitary volume was significantly smaller in patients with OCD as compared with healthy control subjects (11% smaller). Smaller pituitary volume in patients with OCD was associated with increased compulsive but not obsessive symptom severity. Boys with OCD had smaller pituitary gland volumes compared with control boys (20% smaller). No significant differences in pituitary volume were observed between girls with OCD and control girls. Boys with OCD had significantly smaller pituitary volumes than girls with OCD (31% smaller), whereas control boys also had smaller pituitary gland volumes compared with control girls (21% smaller). CONCLUSIONS: These findings provide new evidence of reduced pituitary volume in pediatric OCD that seems to be more prominent in male patients. The observed alterations in pituitary volume are consistent with neuroendocrine studies that have reported abnormalities in the LHPA axis in OCD.  相似文献   
77.
78.
A computational approach which concomitantly determines the capacity-limited rate constants of parent drug elimination and metabolite formation is presented. The approach applies both the presently derived total excretory recovery versus dose relationships of the metabolite and the AUC versus dose relationships of the parent drug to identify the parameters. Three parent drug elimination conditions were assessed: pooled first-order, pooled Michaelis-Menten, and parallel first-order and pooled Michaelis-Menten kinetics. Model and parameter identification criteria are discussed. Literature data for theophylline and two of its metabolites in rats were examined to reveal pooled Michaelis-Menten elimination kinetics of theophylline and capacity-limited formation of the metabolites. The proposed technique is useful for quantitating commonly obtained nonlinear drug disposition data such as AUC and amount of metabolites excreted.  相似文献   
79.
Enantiomerically pure hexahydroquinolinones of the structural type 9 were prepared by a variation of the Hantzsch synthesis in which an optically active acetoacetate served as a chiral auxiliary reagent. Determinations of the de and ee values are described. The absolute configurations of the optically pure products were characterized by single-crystal X-ray analysis. The antipodes 9a and 9b exhibited calcium antagonistic activities on smooth musculature; the (S)-(-)-enantiomer 9b was the more potent compound with regard to the EC50 values which differed by a factor of 100; the intrinsic activity of 9b was 1.2, compared with a value of 0.54 for 9a. On the other hand, R-(+)-9a exerted positive inotropic effects on electrically stimulated atria. The cause of these effects is discussed.  相似文献   
80.
1.5 tesla magnetic resonance imaging of acute spinal trauma   总被引:2,自引:0,他引:2  
Fifty patients with spinal injury above L2 were studied with MRI; forty-two had initial and followup studies permitting correlation of MRI abnormalities with neurologic improvement. Two discrete patterns of MRI abnormality were identified, presumably representing cord hemorrhage and edema respectively. A third pattern appeared to represent a mixed type of injury. The correlation between the MRI patterns of cord injury and neurologic recovery was excellent. The ability of MRI to demonstrate and characterize acute cord injury appears to exceed that of other diagnostic techniques.  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