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   270874篇
  免费   7316篇
  国内免费   799篇
耳鼻咽喉   2206篇
儿科学   9494篇
妇产科学   5374篇
基础医学   29436篇
口腔科学   3719篇
临床医学   19995篇
内科学   52258篇
皮肤病学   2904篇
神经病学   25550篇
特种医学   12572篇
外国民族医学   23篇
外科学   42082篇
综合类   3959篇
一般理论   47篇
预防医学   23390篇
眼科学   4241篇
药学   17205篇
  3篇
中国医学   1147篇
肿瘤学   23384篇
  2023年   419篇
  2022年   903篇
  2021年   1910篇
  2020年   1250篇
  2019年   1730篇
  2018年   23727篇
  2017年   18775篇
  2016年   20964篇
  2015年   2925篇
  2014年   3426篇
  2013年   4620篇
  2012年   12004篇
  2011年   26054篇
  2010年   22028篇
  2009年   14416篇
  2008年   23896篇
  2007年   26252篇
  2006年   5119篇
  2005年   6586篇
  2004年   8055篇
  2003年   8842篇
  2002年   7007篇
  2001年   3975篇
  2000年   4055篇
  1999年   3124篇
  1998年   1348篇
  1997年   1097篇
  1996年   916篇
  1995年   905篇
  1994年   800篇
  1993年   727篇
  1992年   1816篇
  1991年   1842篇
  1990年   1616篇
  1989年   1517篇
  1988年   1378篇
  1987年   1220篇
  1986年   1190篇
  1985年   1064篇
  1984年   788篇
  1983年   716篇
  1982年   473篇
  1980年   393篇
  1979年   570篇
  1978年   425篇
  1975年   433篇
  1974年   502篇
  1973年   464篇
  1972年   422篇
  1971年   393篇
排序方式: 共有10000条查询结果,搜索用时 468 毫秒
1.
The regulation of food intake is a complex mechanism, and the hypothalamus is the main central structure implicated. In particular, the arcuate nucleus appears to be the most critical area in the integration of multiple peripheral signals.Among these signals, those originating from the white adipose tissue and the gastrointestinal tract are known to be involved in the regulation of food intake.The present paper focuses on adiponectin, an adipokine secreted by white adipose tissue, which is reported to have a role in the control of feeding by acting centrally. The recent observation that adiponectin is also able to influence gastric motility raises the question of whether this action represents an additional peripheral mechanism that concurs with the central effects of the hormone on food intake. This possibility, which represents an emerging aspect correlating the central and peripheral effects of adiponectin in the hunger-satiety cycle, is discussed in the present paper.  相似文献   
2.
Purpose: To use polymerase chain reaction (PCR) and Goldmann-Witmer coefficient (GWC) calculation to diagnose infectious uveitis.

Methods: Prospective cross-sectional study.

Results: Twenty-seven of 106 patients had positive PCR and/or GWC results on aqueous humor (AH) sampling and 15 of 27 (55.6%) were HIV-positive. Patients with non-anterior uveitis (NAU) were more likely to be HIV+ (p = 0.005). More than 1 possible pathogen was identified in 9 of 27 patients of whom 7 were HIV+. The final clinical diagnosis was discordant with AH findings in 9 of 27 cases. A positive EBV PCR result was associated with a discordant diagnosis (p = 0.001). All cases of herpetic anterior uveitis (42.9% HIV+) tested PCR-/GWC+ while all cases of herpetic NAU tested PCR+/GWC- (83.3% HIV+). All rubella virus cases were PCR+/GWC+.

Conclusion: PCR is useful to diagnose herpetic NAU in HIV+ patients while GWC is useful to diagnose herpetic anterior uveitis.  相似文献   

3.
4.
5.
Magnetic field generated by neuronal activity could alter magnetic resonance imaging (MRI) signals but detection of such signal is under debate. Previous researches proposed that magnitude signal change is below current detectable level, but phase signal change (PSC) may be measurable with current MRI systems. Optimal imaging parameters like echo time, voxel size and external field direction, could increase the probability of detection of this small signal change. We simulate a voxel of cortical column to determine effect of such parameters on PSC signal. We extended a laminar network model for somatosensory cortex to find neuronal current in each segment of pyramidal neurons (PN). 60,000 PNs of simulated network were positioned randomly in a voxel. Biot–savart law applied to calculate neuronal magnetic field and additional phase. The procedure repeated for eleven neuronal arrangements in the voxel. PSC signal variation with the echo time and voxel size was assessed. The simulated results show that PSC signal increases with echo time, especially 100/80 ms after stimulus for gradient echo/spin echo sequence. It can be up to 0.1 mrad for echo time = 175 ms and voxel size = 1.48 × 1.48 × 2.18 mm3. With echo time less than 25 ms after stimulus, it was just acquired effects of physiological noise on PSC signal. The absolute value of the signal increased with decrease of voxel size, but its components had complex variation. External field orthogonal to local surface of cortex maximizes the signal. Expected PSC signal for tactile detection in the somatosensory cortex increase with echo time and have no oscillation.  相似文献   
6.
7.
8.
9.
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