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   48141篇
  免费   3500篇
  国内免费   196篇
耳鼻咽喉   571篇
儿科学   1009篇
妇产科学   1000篇
基础医学   6670篇
口腔科学   1013篇
临床医学   4765篇
内科学   10112篇
皮肤病学   1099篇
神经病学   4571篇
特种医学   1967篇
外国民族医学   2篇
外科学   8683篇
综合类   499篇
一般理论   77篇
预防医学   2704篇
眼科学   939篇
药学   2820篇
中国医学   75篇
肿瘤学   3261篇
  2023年   468篇
  2022年   927篇
  2021年   1721篇
  2020年   1027篇
  2019年   1352篇
  2018年   1533篇
  2017年   1034篇
  2016年   1204篇
  2015年   1389篇
  2014年   1876篇
  2013年   2192篇
  2012年   3572篇
  2011年   3523篇
  2010年   1952篇
  2009年   1736篇
  2008年   2747篇
  2007年   2804篇
  2006年   2606篇
  2005年   2419篇
  2004年   2246篇
  2003年   2044篇
  2002年   1872篇
  2001年   537篇
  2000年   538篇
  1999年   553篇
  1998年   434篇
  1997年   343篇
  1996年   262篇
  1995年   251篇
  1994年   210篇
  1993年   216篇
  1992年   377篇
  1991年   345篇
  1990年   324篇
  1989年   284篇
  1988年   271篇
  1987年   251篇
  1986年   242篇
  1985年   267篇
  1984年   221篇
  1983年   207篇
  1982年   170篇
  1981年   158篇
  1980年   171篇
  1979年   188篇
  1978年   154篇
  1977年   142篇
  1976年   138篇
  1974年   147篇
  1972年   122篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
To investigate the mechanisms by which oxytocin improves socioaffective processing, we measured behavioral and pupillometric data during a dynamic facial emotion recognition task. In a double‐blind between‐subjects design, 47 men received either 24 IU intranasal oxytocin (OXT) or a placebo (PLC). Participants in the OXT group recognized all facial expressions at lower intensity levels than did participants in the PLC group. Improved performance was accompanied by increased task‐related pupil dilation, indicating an increased recruitment of attentional resources. We also found increased pupil dilation during the processing of female compared with male faces. This gender‐specific stimulus effect diminished in the OXT group, in which pupil size specifically increased for male faces. Results suggest that improved emotion recognition after OXT treatment might be due to an intensified processing of stimuli that usually do not recruit much attention.  相似文献   
994.
Sports-related concussion is the most common athletic head injury with football having the highest rate among high school athletes. Traditionally, research on the biomechanics of football-related head impact has been focused at the collegiate level. Less research has been performed at the high school level, despite the incidence of concussion among high school football players. The objective of this study is to twofold: to quantify the head impact exposure in high school football, and to develop a cumulative impact analysis method. Head impact exposure was measured by instrumenting the helmets of 40 high school football players with helmet mounted accelerometer arrays to measure linear and rotational acceleration. A total of 16,502 head impacts were collected over the course of the season. Biomechanical data were analyzed by team and by player. The median impact for each player ranged from 15.2 to 27.0 g with an average value of 21.7 (±2.4) g. The 95th percentile impact for each player ranged from 38.8 to 72.9 g with an average value of 56.4 (±10.5) g. Next, an impact exposure metric utilizing concussion injury risk curves was created to quantify cumulative exposure for each participating player over the course of the season. Impacts were weighted according to the associated risk due to linear acceleration and rotational acceleration alone, as well as the combined probability (CP) of injury associated with both. These risks were summed over the course of a season to generate risk weighted cumulative exposure. The impact frequency was found to be greater during games compared to practices with an average number of impacts per session of 15.5 and 9.4, respectively. However, the median cumulative risk weighted exposure based on combined probability was found to be greater for practices vs. games. These data will provide a metric that may be used to better understand the cumulative effects of repetitive head impacts, injury mechanisms, and head impact exposure of athletes in football.  相似文献   
995.
996.
Multicellular spheroids are useful models of mammalian tissue for studies of cell proliferation, differentiation, replacement therapies and drug action. Having a size of 100–500 μm they mimic in vivo micro-environment and characteristic gradients of O2, pH and nutrients. We describe the use of cell-penetrating O2 probes based on phosphorescent Pt-porphyrins to perform high-resolution 2D and 3D mapping of O2 in spheroid structures by live cell fluorescence imaging technique. Optimised procedures for preparation of neurospheres from cortical neural cells isolated from embryonic rat brain, their staining with the phosphorescent O2 probes NanO2 and MM2 and subsequent analysis of oxygenation on different live cell imaging platforms, including widefield and confocal phosphorescence lifetime imaging microscopy (PLIM), conventional confocal and two-photon ratiometric intensity based O2 detection are presented. This is followed by a series of physiological experiments in which oxygenation patterns of the neurospheres are correlated with culturing conditions (atmospheric hypoxia and hyperoxia, size, growth factors), distribution of stem cells, mature neurons and astrocytes, HIF-2α stabilisation and responses to metabolic stimulation. The O2 imaging method allows multiplexing with many conventional fluorescent probes to perform multi-parametric imaging analysis of cells in 3D microenvironment. It can be applied to other types of spheroids and 3D tissue models.  相似文献   
997.
Recently, it has been shown that increased level of LDL-containing circulating immune complexes (LDL-CIC) possess high diagnostic significance in clinically manifested atherosclerosis, but little is known about its diagnostic and prognostic significance in early atherosclerosis. Two-years prospective study was performed in 98 asymptomatic men aged 40–74. The rate of atherosclerosis progression was estimated by high-resolution B-mode ultrasonography as the increase in intima-media thickness (IMT) of common carotid arteries. The patients with elevated baseline levels of LDL-CIC were characterized by significantly higher levels of total and LDL cholesterol as well as significantly increased mean IMT of common carotid arteries. Among all baseline lipid parameters, only LDL-CIC and LDL cholesterol were contingent with the extent of early carotid atherosclerosis (p?=?0.042 and p?=?0.049, respectively) and had the highest levels of relative risk and odds ratio. During the follow up, significant IMT increase was registered in 53.1 % (n?=?52) patients, IMT significant reduction was observed in 21.4 % (n?=?21) patients. The increased levels of LDL-CIC, total serum cholesterol and LDL cholesterol had similar prognostic significance with the respect of atherosclerosis progression. The normal level of LDL-CIC (below than 16.0 μg/ml) was the only lipid parameter that predicted the absence of carotid atherosclerosis progression for two following years at prognostic value of 78.3 %. The results of the study allow assuming that LDL-CIC level may be employed not only as a marker of early atherosclerosis, but also has a sufficient prognostic value for clinical implications.  相似文献   
998.
We describe a boy who developed autoinflammatory (chronic sterile multifocal osteomyelitis) and autoimmune (autoimmune cytopenias; vitiligo) phenotypes who subsequently developed disseminated granulomatous disease. Whole exome sequencing revealed homozygous RAG1 mutations thus expanding the spectrum of combined immunodeficiency with autoimmunity and granuloma that can occur with RAG deficiency.  相似文献   
999.
Journal of Autism and Developmental Disorders - Previous studies have reported positive correlations between autistic traits and disordered eating, though it is unclear whether the association is...  相似文献   
1000.
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