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   23558篇
  免费   1966篇
  国内免费   849篇
耳鼻咽喉   191篇
儿科学   166篇
妇产科学   572篇
基础医学   1532篇
口腔科学   564篇
临床医学   3092篇
内科学   1472篇
皮肤病学   95篇
神经病学   839篇
特种医学   748篇
外科学   1532篇
综合类   4314篇
一般理论   5篇
预防医学   3710篇
眼科学   177篇
药学   3727篇
  76篇
中国医学   3206篇
肿瘤学   355篇
  2024年   170篇
  2023年   527篇
  2022年   1121篇
  2021年   1357篇
  2020年   1186篇
  2019年   887篇
  2018年   915篇
  2017年   978篇
  2016年   1041篇
  2015年   957篇
  2014年   1890篇
  2013年   2343篇
  2012年   1775篇
  2011年   1770篇
  2010年   1300篇
  2009年   1106篇
  2008年   1153篇
  2007年   1029篇
  2006年   864篇
  2005年   682篇
  2004年   571篇
  2003年   504篇
  2002年   348篇
  2001年   302篇
  2000年   254篇
  1999年   188篇
  1998年   161篇
  1997年   137篇
  1996年   125篇
  1995年   106篇
  1994年   85篇
  1993年   66篇
  1992年   80篇
  1991年   51篇
  1990年   52篇
  1989年   49篇
  1988年   36篇
  1987年   43篇
  1986年   21篇
  1985年   25篇
  1984年   20篇
  1983年   17篇
  1982年   18篇
  1981年   15篇
  1980年   15篇
  1979年   8篇
  1978年   7篇
  1977年   6篇
  1976年   3篇
  1973年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Abstract Daan's two process model is known to be one of the most powerful models, covering various situations from free-running to sleep deprivation. In this study, bifurcation properties of the model dynamics as function of a gap, D , between the threshold processes are clarified using a circle map. As a function of D , we will show that the model has the different types of the mutual entrainment regions that are intervened by the tangent bifurcation. The variable behavior of human circadian rhythm is suggested to be systematically understood based on the bifurcation properties of the two process model.  相似文献   
22.
23.
Potent inhibition of HIV-1 entry by (s4dU)35   总被引:2,自引:0,他引:2  
  相似文献   
24.
The majority of winter-type seasonal affective disorder (SAD) patients complain of hypersomnia and daytime drowsiness. As human sleep is regulated by the interaction of circadian, ultradian and homeostatic processes, sleep disturbances may be caused by either one of these factors. The present study focuses on homeostatic and ultradian aspects of sleep regulation in SAD. Sleep was recorded polysomnographically in seven SAD patients and matched controls subjected to a 120-h forced desynchrony protocol. In time isolation, subjects were exposed to six 20-h days, each comprising a 6.5-h period for sleep. Patients participated while being depressed, while remitted after light therapy and in summer. Controls were studied in winter and in summer. In each condition, the data of each subject were averaged across all recordings. Thus, the influence of the effects of the circadian pacemaker on sleep was excluded mathematically. The comparison of patients with controls and with themselves in the various conditions revealed no abnormalities in homeostatic parameters: sleep stage variables, relative power spectra and time courses of power in various frequency bands across the first three non-rapid eye movement-rapid eye movement (NREM-REM) cycles showed no differences. The data suggest that homeostatic processes are not involved in the disturbance of sleep in SAD.  相似文献   
25.
26.
27.
We comment on the target article by Weingardt (this issue), which discusses recent advances in instructional design and technology (IDT) and their implications for dissemination of evidence-based practices. These arguments are extended to the topic of psychological intervention design, and possibilities for new intervention structures are briefly explored. Finally, comments are offered on maintaining a careful balance between technological and social processes in the effort to promote the dissemination of innovative and evidence-based psychological procedures.  相似文献   
28.
29.
A recently reported device, the sorbent suspension reciprocating dialyser (SSRD), was investigated for use as a test system for biocompatibility of dialyser components. The device is easy to assemble and operate, and allows minimal blood contact with foreign material outside of dialyser components. Its constant pressure/ variable flow rate operation allows quantification of degree of clotting of dialyser versus time. The effect of heparinization of the blood distribution gaskets (BDG) of the device on performance and dialyser lifetime was investigated. Heparin was bound to the surface of polyethylene gaskets by immersion in a solution of tridodecylmethylammonium chloride (TDMAC)-heparin complex for several hours. Gaskets were then assembled in an SSRD which was then used for experimental dialysis in dogs with AV shunts. Dialysers assembled using non-heparinized gaskets were used as controls. Blood coagulation tendency was quantified by the activated clotting time (ACT) and partial thromboplastin time (PTT), and these values correlated with the rate of clotting of the device. Heparinization of the gaskets resulted in the prevention of clotting in the dialyser until the final minutes of dialysis in all cases, in contrast to the constant decay of blood fill volume and evidence of clotting in the non-heparinized cases. However, dialyser lifetime was not significantly increased by gasket heparinization. At normal initial values of ACT (80–95 s) dialyser clotting occurred in 10–15 mia In tests with non-heparinized gaskets and systemically heparinized dogs, values obtained in the ACT test were observed to decrease during dialysis, indicating the disappearance of heparin from the blood. Both ACT and PTT tests show promise as predictors of dialyser lifetime.  相似文献   
30.
科技进步与心血管病学的50年展望   总被引:5,自引:2,他引:3  
本文主要阐述未来50年心血管病学领域内的各种进步,包括基因诊断和治疗、心脏外科手术的发展等等.  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