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   9635篇
  免费   671篇
  国内免费   29篇
耳鼻咽喉   56篇
儿科学   165篇
妇产科学   222篇
基础医学   1314篇
口腔科学   233篇
临床医学   822篇
内科学   2371篇
皮肤病学   113篇
神经病学   1164篇
特种医学   347篇
外科学   1027篇
综合类   122篇
一般理论   10篇
预防医学   913篇
眼科学   341篇
药学   667篇
  1篇
中国医学   8篇
肿瘤学   439篇
  2023年   66篇
  2022年   94篇
  2021年   190篇
  2020年   125篇
  2019年   176篇
  2018年   197篇
  2017年   123篇
  2016年   169篇
  2015年   165篇
  2014年   224篇
  2013年   400篇
  2012年   499篇
  2011年   549篇
  2010年   325篇
  2009年   319篇
  2008年   489篇
  2007年   537篇
  2006年   511篇
  2005年   573篇
  2004年   470篇
  2003年   429篇
  2002年   436篇
  2001年   207篇
  2000年   218篇
  1999年   202篇
  1998年   136篇
  1997年   96篇
  1996年   89篇
  1995年   78篇
  1994年   63篇
  1993年   65篇
  1992年   140篇
  1991年   129篇
  1990年   104篇
  1989年   89篇
  1988年   86篇
  1987年   69篇
  1986年   78篇
  1985年   81篇
  1984年   56篇
  1983年   69篇
  1982年   69篇
  1981年   69篇
  1980年   55篇
  1979年   61篇
  1978年   63篇
  1977年   58篇
  1975年   52篇
  1974年   53篇
  1970年   54篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Identity     
Gilner  Leon I. 《JAMA》2003,290(24):3172
  相似文献   
42.
43.
Male and female dropouts and graduates (N = 248) from a traditional drug-free therapeutic community were followed 2 years after treatment. A 4-hr face-to-face interview traced the social adjustment one year pre-, through all years posttreatment. Results showed that (a) success (no crime and no opioid and/or no use of nonopioid primary drug) was maintained through 2 years of follow-up by 34% of the dropouts and 68% of the graduates; (b) success rates were highest among opioid abusers and the lowest among primary alcohol abusers; (c) among the latter, however, abstinence rates were significantly increased and daily use of alcohol significantly decreased as did criminal involvement; (d) among the opioid abstinent group, alcohol use increased posttreatment but heavy drinking was not prominent indicating no significant shift in substance dependency. Overall, the therapeutic community appears most effective for opioid abusers but has a clear impact on a considerable number of those primarily involved with alcohol and other substance use.  相似文献   
44.
45.
Olfactory stimulation evokes a column of activity within the olfactory bulb extending from the glomerular layer to the granule cell layer that can be visualized with 2-deoxyglucose autoradiography, optical imaging, Fos protein immunohistochemistry and c-fos mRNA in situ hybridization. The Fos response to odors is typified by the activity of relatively few juxtaglomerular cells, which often occur in foci, and a large number of granule cells extending through much of the bulb. In this study, we characterized the granule cell response to an odor for which young rats had acquired a preference. Fos-like immunoreactive granule cells were quantified by image analysis, and densely stained cells were counted in a region previously shown to be responsive to peppermint odor. We found that odor-trained pups have about half the number of Fos-immunopositive superficial granule cells which respond to a learned odor than do control pups. We then determined whether there was a correlation between the juxtaglomerular cell response and the response of the superficial granule cells deep to those glomerular layer cells. We found a positive correlation between the number of juxtaglomerular cells and the number of granule cells demonstrating Fos immunoreactivity in both control and trained pups, a relationship that changed with early olfactory training.  相似文献   
46.
MRI studies of first-pass contrast enhancement with polylysine-Gd-DTPA and myocardial tagging using spatial modulation of magnetization (SPAMM) were performed to assess the feasibility of a combined regional myocardial blood flow and 2D deformation exam. Instrumented closed-chest dogs were imaged at a baseline control state (Cntl) followed by two interventions: moderate coronary stenosis (St) achieved by partial occlusion of the left anterior descending (LAD) and moderate coronary stenosis with dobutamine loading (StD). Hypoperfusion of the anterior region (ANT) of the myocardium (LAD distribution) relative to the posterior wall (POS) based on the upslope of the signal intensity time curve from the contrast-enhanced MR images was demonstrated only with dobutamine loading (ANT:POS Cntl=1.077 ± 0.15 versus ANT:POS StD=0.477 ± 0.11, P<0.03) and was confirmed with radio-labeled microspheres measurements (ANT:POS Cntl=1.18 ± 0.2 ml/min/g versus ANT:POS StD=0.44 ± 0.1 ml/min/g; P<0.002). Significant changes in regional myocardial shortening were only seen in the StD state (P<0.02); the anterior region showed impaired myocardial shortening with dobutamine loading (P=NS), whereas the nonaffected POS region showed a marked increase in shortening when compared with Cntl (Cntl=0.964 ± 0.02 versus StD=0.884 ± 0.03; P<0.001). These results demonstrate that an integrated quantitative assessment of regional myocardial function and semiquantitative assessment of myocardial blood flow can be performed noninvasively with ultrafast MRI.  相似文献   
47.
Key words  axillary - block  相似文献   
48.
49.
In the past two decades, there has been a gradual trend to regionalization of perinatal care, categorization of hospitals and transport services for neonatal health care. The literature alludes to both beneficial and deleterious effects of neonatal transport (T) but no controls such as a matched nontransport (NT) population have been utilized to date.The major goal of this study was to evaluate the effect of neonatal transport from Level I and II high risk 2500 gm. neonates (born in NYC in one calendar year, 1979) compared to a cohort nontransported population matched for hospital of birth, weight, race, sex and risk. All transported 2500 gm. from Level I and II (n=328) were studied and a stratified random sample of the nontransported (NT) infants 2500 gm. from these same hospitals (n=2042) was used for comparison. The principle outcome variable was survival. The major conclusion of this study is that in Level I and II hospitals the transport group had a significantly increased survival in infants who were sick (Apgar <6) compared to cohorted nontransported controls. Interhospital differences in survival were noted among Level I and II but not seen in the subdivisions of (A) and (B) hospitals.Angelo Ferrara, M.D., Ph.D., is Professor, Pediatrics, NYU Medical Center, New York, N.Y.: Melvin Schwartz, M.D., was Research Professor, Environmental Medicine, NYU Medical Center, New York, N.Y.; Helen Page, R.N., M.P.A., is Quality Assurance Reviewer, Manhattan Eye, Ear, Throat Hospital, New York, N.Y.: Morton Israel, M.A., is Research Scientist, Health Resources Administration, City of N. Y., New York, N.Y.; Yucel Atakent, M.D., M.S., is Clinical Associate Professor, NYU Medical Center, New York, N.Y.; C.E. Smith, Ph.D., is President, Health Policy Analysis & Accountability Network, Inc. (HPAAN), Edgewood, New Mexico; Leon Landovitz, Ph.D., is Vice President, Management Information Systems, Healthways System Inc., Islin, N.J.Supported by NCHSR Grant #5-R018-HSO3832  相似文献   
50.
Labelled proteins conveyed by fast axonal transport into the sensory axons of frog sciatic nerve following axotomy have been studied by 2D gel electrophoresis. Previous work showed that in frogs acclimatized to 25 °C a cell body reaction occurs, along with regeneration of axons to their targets. In contrast, frogs acclimatized to 15 °C showed no cell body reaction and though regeneration began, it stalled after approximately 35 days. We found that axotomy at 25 °C was followed by an increase in transport of specific labelled proteins corresponding to growth-associated proteins (GAPs) identified in other regenerating systems. Surprisingly, axotomy at 15 °C also induced a similar increase, though with a slower onset, so that the highest levels of expression of GAPs occurred during the time when the axons had stalled. We conclude that sensory neurons in 15 °C frogs do detect that their axons have been injured, as shown by their ability to increase GAP synthesis. Slow and limited axonal growth is possible during a period when GAP synthesis is low compared to levels in rapidly regenerating nerves, but even when the ability to produce GAPs increases, this alone is not sufficient to sustain regeneration in the absence of other components of the cell body reaction to injury.  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