全文获取类型
收费全文 | 6740篇 |
免费 | 687篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 79篇 |
儿科学 | 318篇 |
妇产科学 | 171篇 |
基础医学 | 863篇 |
口腔科学 | 173篇 |
临床医学 | 977篇 |
内科学 | 1512篇 |
皮肤病学 | 57篇 |
神经病学 | 695篇 |
特种医学 | 192篇 |
外科学 | 849篇 |
综合类 | 178篇 |
一般理论 | 17篇 |
预防医学 | 534篇 |
眼科学 | 71篇 |
药学 | 378篇 |
肿瘤学 | 381篇 |
出版年
2021年 | 91篇 |
2020年 | 60篇 |
2019年 | 98篇 |
2018年 | 107篇 |
2017年 | 97篇 |
2016年 | 85篇 |
2015年 | 114篇 |
2014年 | 141篇 |
2013年 | 211篇 |
2012年 | 299篇 |
2011年 | 272篇 |
2010年 | 174篇 |
2009年 | 166篇 |
2008年 | 246篇 |
2007年 | 258篇 |
2006年 | 258篇 |
2005年 | 272篇 |
2004年 | 232篇 |
2003年 | 249篇 |
2002年 | 198篇 |
2001年 | 198篇 |
2000年 | 217篇 |
1999年 | 205篇 |
1998年 | 127篇 |
1997年 | 103篇 |
1996年 | 78篇 |
1995年 | 74篇 |
1994年 | 73篇 |
1993年 | 69篇 |
1992年 | 162篇 |
1991年 | 168篇 |
1990年 | 170篇 |
1989年 | 178篇 |
1988年 | 155篇 |
1987年 | 179篇 |
1986年 | 150篇 |
1985年 | 130篇 |
1984年 | 117篇 |
1983年 | 100篇 |
1982年 | 60篇 |
1981年 | 68篇 |
1980年 | 70篇 |
1979年 | 116篇 |
1978年 | 82篇 |
1977年 | 66篇 |
1976年 | 50篇 |
1975年 | 68篇 |
1974年 | 72篇 |
1973年 | 67篇 |
1972年 | 58篇 |
排序方式: 共有7445条查询结果,搜索用时 15 毫秒
91.
BIOETHICS IS NOW TAUGHT IN EVERY CANADIAN MEDICAL SCHOOL. Canada needs a cadre of teachers who can help clinicians learn bioethics. Our purpose is to encourage clinician teachers to accept this important responsibility and to provide practical advice about teaching bioethics to clinicians as an integral part of good clinical medicine. We use 5 questions to focus the discussion: Why should I teach? What should I teach? How should I teach? How should I evaluate? How should I learn? 相似文献
92.
93.
Emilia J. Ling Molly Frean Jody So Maike Tietschert Nancy Song Christian Covington Hassina Bahadurazada Sonia Khurana Luis Garcia Sara J. Singer 《Health services research》2021,56(3):507
ObjectiveThis study sought to identify potential disparities among racial/ethnic groups in patient perceptions of integrated care (PPIC) and to explore how methodological differences may influence measured disparities.Data SourceData from Medicare beneficiaries who completed the 2015 Medicare Current Beneficiary Survey (MCBS) and were enrolled in Part A benefits for an entire year.Study DesignWe used 4‐point measures of eight dimensions of PPIC and assessed differences in dimensions among racial/ethnic groups. To estimate differences, we applied a “rank and replace” method using multiple regression models in three steps, balancing differences in health status among racial groups and adjusting for differences in socioeconomic status. We reran all analyses with additional SES controls and using standard multiple variable regression.Data Collection/Extraction MethodsNot applicable.Principal FindingsWe found several significant differences in perceived integrated care between Black versus White (three of eight measures) and Hispanic versus White (one of eight) Medicare beneficiaries. On average, Black beneficiaries perceived more integrated support for self‐care than did White beneficiaries (mean difference = 0.14, SE = 0.06, P =.02). Black beneficiaries perceived more integrated specialists’ knowledge of past medical history than did White beneficiaries (mean difference = 0.12, SE = 0.06, P =.01). Black and Hispanic beneficiaries also each reported, on average, 0.18 more integrated medication and home health management than did White beneficiaries (P <.01 and P <.01). These findings were robust to sensitivity analyses and model specifications.ConclusionsThere exist some aspects of care for which Black and Hispanic beneficiaries may perceive greater integrated care than non‐Hispanic White beneficiaries. Further studies should test theories explaining why racial/ethnic groups perceive differences in integrated care. 相似文献
94.
Sulfation of L-selectin ligands by an HEV-restricted sulfotransferase regulates lymphocyte homing to lymph nodes 总被引:13,自引:0,他引:13
Hemmerich S Bistrup A Singer MS van Zante A Lee JK Tsay D Peters M Carminati JL Brennan TJ Carver-Moore K Leviten M Fuentes ME Ruddle NH Rosen SD 《Immunity》2001,15(2):237-247
Lymphocytes home to lymph nodes, using L-selectin to bind specific ligands on high endothelial venules (HEV). In vitro studies implicate GlcNAc-6-sulfate as an essential posttranslational modification for ligand activity. Here, we show that genetic deletion of HEC-GlcNAc6ST, a sulfotransferase that is highly restricted to HEV, results in the loss of the binding of recombinant L-selectin to the luminal aspect of HEV, elimination of lymphocyte binding in vitro, and markedly reduced in vivo homing. Reactivity with MECA 79, an adhesion-blocking mAb that stains HEV in lymph nodes and vessels in chronic inflammatory sites, is also lost from the luminal aspects of HEV. These results establish a critical role for HEC-GlcNAc6ST in lymphocyte trafficking and suggest it as an important therapeutic target. 相似文献
95.
M Singer 《Journal of adolescence》1990,13(2):143-155
The study examined age and gender differences in leadership aspirations among teenage adolescents. It was hypothesized that adolescents' valence, self-efficacy and attribution perceptions about leadership would be predictive of their aspirations to leadership. Altogether 52 fourth form and 78 seventh form high school students completed a questionnaire measuring (a) overall leadership aspirations, (b) 13 valence-instrumentality expectancies for 13 leadership outcomes, (c) self-efficacy perceptions, and (d) attributions of effective leadership. The results revealed significant gender differences in valence scores and significant age differences in self-efficacy and attribution measures. Regression analyses indicated that fourth formers' leadership aspirations were significantly predicted from their "ease-of-success" self-efficacy expectation; whereas seventh formers from either valence perceptions (males) or self-efficacy and attribution scores (females). These results were discussed in the context of the valence and self-efficacy models of career decision-making processes and attribution theory. 相似文献
96.
The current source-density (CSD) analysis was used to investigate the organization of tangential synaptic connections in primary visual cortex of normally reared (NR) kittens and of NR, binocularly deprived (BD) and dark-reared (DR) adult cats. Laminar profiles of field potentials, elicited by intracortical microstimulation were measured at various distances from the stimulating electrodes. To exclude contamination by axon collaterals of antidromically stimulated thalamo-cortical fibres, these were destroyed by injecting the cytotoxin N-methyl-D-aspartate (NMDA) into the lateral geniculate nucleus 13 - 27 days before recording. The CSD profiles revealed distinct layer-specific patterns of lateral spread of activity. Invariably, the most prominent, long-lasting and far reaching responses were recorded in supragranular layers. Responses in layer IV were brief and confined to the vicinity of the stimulation site. Responses in infragranular layers spread as far as those in supragranular layers, but were of smaller amplitude. Latency considerations, the results of double shock stimulation, and the effects of translaminar cuts, suggest that these responses were monosynaptic and mediated by intracortical pathways with a conduction velocity of 0.3-5 m/s. The spatial spread of these responses changed substantially with age but was not influenced by visual deprivation. In NR adults, supra- and infragranular responses were recordable up to 2.5 mm from the stimulation site and layer IV responses up to 1 mm from the stimulation site. In kittens, the former responses spread up to 5 mm and the latter up to 2 mm from the site of stimulation. The amplitude of the responses decreased with distance from the stimulation site. This decrease was not always monotonic suggesting inhomogeneities in the tangential projections. The laminar distribution of current sinks and sources indicates that the pathways mediating tangential interactions form excitatory synapses on apical dendrites of pyramidal cells. It is concluded that the spatial spread of tangential excitatory interactions decreases with age, but that neither the laminar pattern nor the age-dependent reduction in the strength of tangential interactions are influenced by visual deprivation. 相似文献
97.
98.
99.
100.