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   19066篇
  免费   1484篇
  国内免费   52篇
耳鼻咽喉   254篇
儿科学   609篇
妇产科学   441篇
基础医学   2780篇
口腔科学   280篇
临床医学   1812篇
内科学   3579篇
皮肤病学   294篇
神经病学   1960篇
特种医学   635篇
外科学   2584篇
综合类   602篇
现状与发展   1篇
一般理论   27篇
预防医学   1515篇
眼科学   545篇
药学   1304篇
中国医学   40篇
肿瘤学   1340篇
  2023年   99篇
  2022年   236篇
  2021年   387篇
  2020年   227篇
  2019年   356篇
  2018年   428篇
  2017年   268篇
  2016年   360篇
  2015年   407篇
  2014年   512篇
  2013年   819篇
  2012年   1149篇
  2011年   1076篇
  2010年   663篇
  2009年   629篇
  2008年   1022篇
  2007年   1031篇
  2006年   928篇
  2005年   1013篇
  2004年   1027篇
  2003年   951篇
  2002年   863篇
  2001年   342篇
  2000年   348篇
  1999年   327篇
  1998年   216篇
  1997年   161篇
  1996年   166篇
  1995年   168篇
  1994年   120篇
  1993年   150篇
  1992年   240篇
  1991年   217篇
  1990年   231篇
  1989年   229篇
  1988年   211篇
  1987年   190篇
  1986年   197篇
  1985年   218篇
  1984年   172篇
  1983年   135篇
  1982年   148篇
  1981年   151篇
  1980年   128篇
  1979年   114篇
  1977年   96篇
  1976年   117篇
  1975年   102篇
  1974年   130篇
  1973年   95篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Summary Chondrocytes in epiphyseal cartilage were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) using freeze-fracture techniques. Freeze-fracture replicas showed large numbers of fingerlike, 0.11–0.15 m diameter, projections from the chondrocyte surface, with numerous 95–180 Å diameter intramembranous particles associated with both the cell membrane surface and these projections. With SEM, these cytoplasmic projections were also obvious, but appeared collapsed into clusters of globular-shaped projections on the surface of the chondrocytes. With freeze-fracture techniques, in which shrinkage artifacts were essentially eliminated, the cytoplasmic projections were often seen in intimate contact with the extracapsular matrix. However, with chondrocytes prepared by both SEM and conventional TEM, there was evidence of shrinkage, the cytoplasmic projections having little contact with the extracapsular matrix. These findings show that the cytoplasmic processes are not artifacts of tissue processing and provide morphological evidence in support of the hypothesis that matrix vesicles are of cellular origin.Correlation of Freeze-Fracture and Scanning Electron Microscopy of Epiphyseal Chondrocytes  相似文献   
103.
Spirochetes found in feces of normal and infected pigs during the eight days preceding the onset of the clinical signs of swine dysentery have been studied using electron and phase contrast microscopy. According to their dimensions, diameter, length and pitch, three morphological groups have been described: small, intermediate and large spirochetes. On the basis of their axial filaments arrangement, eight types have been observed. Compared to the control pigs, there was no increase in the total number of spirochetes in infected pigs, except at day 6 before the onset of clinical signs. However, infected pigs have shown a wide spectrum of different morphological types of spirochetes in comparison to control, uninfected pigs, which showed only the type "1-2-1" spirochete of axial filaments arrangement. This last type was predominant in infected swine during the entire incubation period as compared to other spirochete types described.  相似文献   
104.
105.
The metabolism and fate of phenyl ring-labeled14C-phenthoate {O,O- dimethylS-[-(carboethoxy)benzyl] phosphorodithioate} was examined in the Valencia orange fruit with emphasis on the characterization of bound phenthoate residues in the fruit peel. The products recovered from the citrus fruit wash were unchanged phenthoate, phenthoate oxon, demethyl phenthoate, phenthoate acid, ethyl mandelate, and mandelic acid. The same products, with the exception of phenthoate oxon, were found in the acetone extract of the fruit peel. Enzymatic hydrolysis of the bound residue in the peel with-glucosidase, followed by acidic and basic hydrolysis gave ethyl mandelate as the major product, followed by mandelic acid, demethyl phenthoate and phenthoate acid. Phenthoate was metabolized and conjugated in citrus fruits into detoxication products.  相似文献   
106.
107.
108.
109.
OBJECTIVE: To examine the cost impact of referral to a Mood Disorders Unit (MDU), by comparing pre-service and post-service costs, and MDU and control samples. METHOD: We studied tertiary referral MDU patients and a control group of consultants' depressed patients, with the principal comparison intervals being: (i) 12 months prior to and (ii) 6 months following baseline assessment, with costs annualised to allow the impact of assessment and treatment recommendation to be determined. In addition, we assessed any 'personal cost' of depression. RESULTS: Following baseline assessment, MDU referrals showed a reduction in costs, while controls' costs increased, largely driven by contrasting directions in hospitalisation and social welfare costs. We identify variables associated with high and increased costs, including features of the earlier stages of the disorder, whether social welfare was received, diagnostic subtype and personality dysfunction, with multivariate analyses refining the variable sets. Self-report data indicated that patients judged the 'personal cost' of depression to exceed more formal cost parameters, so that to experience depression is itself depressogenic. CONCLUSIONS: This first Australian attempt to cost depression and its management in the clinical setting more provides a methodology for wider application in service evaluation studies rather than delivers an unequivocal answer to whether a specialist Mood Disorders Unit is cost efficient or not.  相似文献   
110.
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