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   22690篇
  免费   1427篇
  国内免费   214篇
耳鼻咽喉   274篇
儿科学   728篇
妇产科学   610篇
基础医学   3307篇
口腔科学   341篇
临床医学   1765篇
内科学   4471篇
皮肤病学   370篇
神经病学   1757篇
特种医学   667篇
外国民族医学   1篇
外科学   2925篇
综合类   483篇
一般理论   24篇
预防医学   3117篇
眼科学   533篇
药学   1327篇
  2篇
中国医学   145篇
肿瘤学   1484篇
  2023年   174篇
  2022年   288篇
  2021年   671篇
  2020年   319篇
  2019年   568篇
  2018年   705篇
  2017年   497篇
  2016年   537篇
  2015年   626篇
  2014年   845篇
  2013年   1173篇
  2012年   1684篇
  2011年   1777篇
  2010年   1067篇
  2009年   867篇
  2008年   1389篇
  2007年   1501篇
  2006年   1403篇
  2005年   1272篇
  2004年   1150篇
  2003年   1090篇
  2002年   962篇
  2001年   405篇
  2000年   333篇
  1999年   295篇
  1998年   155篇
  1997年   147篇
  1996年   119篇
  1995年   100篇
  1994年   98篇
  1993年   71篇
  1992年   174篇
  1991年   163篇
  1990年   180篇
  1989年   186篇
  1988年   162篇
  1987年   160篇
  1986年   135篇
  1985年   119篇
  1984年   91篇
  1983年   69篇
  1982年   40篇
  1981年   46篇
  1980年   38篇
  1979年   61篇
  1978年   33篇
  1977年   31篇
  1975年   34篇
  1974年   29篇
  1973年   33篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
Facial motion is a primary source of social information about other humans. Prior fMRI studies have identified regions of the superior temporal sulcus (STS) that respond specifically to perceived face movements (termed fSTS), but little is known about the nature of motion representations in these regions. Here we use fMRI and multivoxel pattern analysis to characterize the representational content of the fSTS. Participants viewed a set of specific eye and mouth movements, as well as combined eye and mouth movements. Our results demonstrate that fSTS response patterns contain information about face movements, including subtle distinctions between types of eye and mouth movements. These representations generalize across the actor performing the movement, and across small differences in visual position. Critically, patterns of response to combined movements could be well predicted by linear combinations of responses to individual eye and mouth movements, pointing to a parts‐based representation of complex face movements. These results indicate that the fSTS plays an intermediate role in the process of inferring social content from visually perceived face movements, containing a representation that is sufficiently abstract to generalize across low‐level visual details, but still tied to the kinematics of face part movements.  相似文献   
7.
8.
Our objectives were to study the prevalence, risk factors for carriage, and transmission dynamics of extended-spectrum-β-lactamase (ESBL)-producing Enterobacteriaceae (ESBLPE) in a national survey of cattle. This was a point prevalence study conducted from July to October 2013 in Israel. Stool samples were collected from 1,226 cows in 123 sections on 40 farms of all production types. ESBLPE were identified in 291 samples (23.7%): 287 contained Escherichia coli and 4 contained Klebsiella pneumoniae. The number of ESBLPE-positive cows was the highest in quarantine stations and on fattening farms and was the lowest on pasture farms (P = 0.03). The number of ESBLPE-positive cows was the lowest in sections containing adult cows (age, >25 months) and highest in sections containing calves (age, <4 months) (P < 0.001). Infrastructure variables that were significant risk factors for ESBLPE carriage included crowding, a lack of manure cleaning, and a lack of a cooling (P < 0.001 for each), all of which were more common in sections containing calves. Antimicrobial prophylaxis was given almost exclusively to calves and was associated with a high number of ESBLPE carriers (P < 0.001). The 287 E. coli isolates were typed into 106 repetitive extragenic palindromic (REP)-PCR types and mostly harbored blaCTX-M-1 or blaCTX-M-9 group genes. The isolates on the six farms with ≥15 isolates of ESBLPE were of 4 to 7 different REP-PCR types, with one dominant type being harbored by about half of the isolates. Fourteen types were identified on more than one farm, with only six of the farms being adjacent to each other. The prevalence of ESBLPE carriage is high in calves in cowsheds where the use of antimicrobial prophylaxis is common. ESBLPE disseminate within cowsheds mainly by clonal spread, with limited intercowshed transmission occurring.  相似文献   
9.
This study deals with a series of operations to isolate the micro-cellulose from the palm tree spathe sheath by using a modified chemical method to take into account the low cost and the completion speed and its characterization using X-ray diffraction technique (XRD), infrared spectroscopy (FTIR) and scanning electron microscope coupled with element analyzer (SEM/EDX). The results showed that the extraction method succeeded in obtaining very pure microscopic fibers with a width of 2–10 μm with a crystallinity index equal to 79.21%, containing the two cellulose features Iβ and II, that, the conversion ratio of the first to the second was estimated at 32, 87%.  相似文献   
10.
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