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   172362篇
  免费   12020篇
  国内免费   705篇
耳鼻咽喉   1913篇
儿科学   4177篇
妇产科学   2863篇
基础医学   22847篇
口腔科学   3530篇
临床医学   16774篇
内科学   36857篇
皮肤病学   3500篇
神经病学   16136篇
特种医学   7637篇
外国民族医学   14篇
外科学   27698篇
综合类   1985篇
一般理论   111篇
预防医学   12398篇
眼科学   3430篇
药学   11106篇
中国医学   252篇
肿瘤学   11859篇
  2023年   894篇
  2022年   1355篇
  2021年   3796篇
  2020年   2279篇
  2019年   3525篇
  2018年   4084篇
  2017年   3125篇
  2016年   3475篇
  2015年   3988篇
  2014年   5727篇
  2013年   7597篇
  2012年   11544篇
  2011年   12240篇
  2010年   7003篇
  2009年   6694篇
  2008年   10758篇
  2007年   11145篇
  2006年   11067篇
  2005年   10998篇
  2004年   10133篇
  2003年   9309篇
  2002年   8927篇
  2001年   2271篇
  2000年   1933篇
  1999年   2246篇
  1998年   2044篇
  1997年   1660篇
  1996年   1412篇
  1995年   1322篇
  1994年   1186篇
  1993年   1057篇
  1992年   1348篇
  1991年   1230篇
  1990年   1066篇
  1989年   1015篇
  1988年   952篇
  1987年   916篇
  1986年   911篇
  1985年   887篇
  1984年   942篇
  1983年   813篇
  1982年   973篇
  1981年   865篇
  1980年   732篇
  1979年   657篇
  1978年   654篇
  1977年   537篇
  1976年   517篇
  1974年   525篇
  1973年   455篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
We evaluated RNA stability of Ebola virus in EDTA blood and urine samples collected from infected patients and stored in West Africa’s environmental conditions. In blood, RNA was stable for at least 18 days when initial cycle threshold values were <30, but in urine, RNA degradation occurred more quickly.  相似文献   
52.
53.
The specific role of postsynaptic activity for the generation of a functional magnetic resonance imaging (fMRI) response was determined by a simultaneous measurement of generated field excitatory postsynaptic potentials (fEPSPs) and blood oxygen level-dependent (BOLD) response in the rat hippocampal CA1 region during electrical stimulation of the contralateral CA3 region. The stimulation electrode was placed either in the left CA3a/b or CA3c, causing the preferentially basal or apical dendrites of the pyramidal cells in the right CA1 to be activated. Consecutive stimulations with low-intensity stimulation trains (i.e., 16 pulses for 8 seconds) resulted in clear postsynaptic responses of CA1 pyramidal cells, but in no significant BOLD responses. In contrast, consecutive high-intensity stimulation trains resulted in stronger postsynaptic responses that came along with minor (during stimulation of the left CA3a/b) or substantial (during stimulation of the left CA3c) spiking activity of the CA1 pyramidal cells, and resulted in the generation of significant BOLD responses in the left and right hippocampus. Correlating the electrophysiologic parameters of CA1 pyramidal cell activity (fEPSP and spiking activity) with the resultant BOLD response revealed no positive correlation. Consequently, postsynaptic activity of pyramidal cells, the most abundant neurons in the CA1, is not directly linked to the measured BOLD response.  相似文献   
54.
55.
56.
57.
58.
59.

Background

Nursing Home Compare (NHC) ratings, created and maintained by Medicare, are used by both hospitals and consumers to aid in the skilled nursing facility (SNF) selection process. To date, no studies have linked NHC ratings to actual episode-based outcomes. The purpose of this study was to evaluate whether NHC ratings are valid predictors of 90-day complications, readmission, and bundle costs for patients discharged to an SNF after primary total joint arthroplasty (TJA).

Methods

All SNF-discharged primary TJA cases in 2017 at a multihospital academic health system were queried. Demographic, psychosocial, and clinical variables were manually extracted from the health record. Medicare NHC ratings were then collected for each SNF. For patients in the Medicare bundle, postacute and total bundle cost was extracted from claims.

Results

Four hundred eighty-eight patients were discharged to a total of 105 unique SNFs. In multivariate analysis, overall NHC rating was not predictive of 90-day readmission/major complications, >75th percentile postacute cost, or 90-day bundle cost exceeding the target price. SNF health inspection and quality measure ratings were also not predictive of 90-day readmission/major complications or bundle performance. A higher SNF staffing rating was independently associated with a decreased odds for >75th percentile 90-day postacute spend (odds ratio, 0.58; P = .01) and a 90-day bundle cost exceeding the target price (odds ratio = 0.69; P = .02) but was similarly not predictive of 90-day readmission/complications.

Conclusion

Results of our study suggest that Medicare's NHC tool is not a useful predictor of 90-day costs, complications, or readmissions for SNFs within our health system.  相似文献   
60.
Several regulatory bodies have agreed that low-dose radiation used in medical imaging is a weak carcinogen that follows a linear, non-threshold model of cancer risk. While avoiding radiation is the best course of action to mitigate risk, computed tomography (CT) scans are often critical for diagnosis. In addition to the as low as reasonably achievable principle, a more concrete method of dose reduction for common CT imaging exams is the use of a diagnostic reference level (DRL). This paper examines Canada's national DRL values from the recent CT survey and compares it to published provincial DRLs as well as the DRLs in the United Kingdom and the United States of America for the 3 most common CT exams: head, chest, and abdomen/pelvis. Canada compares well on the international scale, but it should consider using more electronic dose monitoring solutions to create a culture of dose optimization.  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