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   159801篇
  免费   11478篇
  国内免费   729篇
耳鼻咽喉   1849篇
儿科学   3982篇
妇产科学   2832篇
基础医学   20667篇
口腔科学   3211篇
临床医学   15893篇
内科学   33389篇
皮肤病学   2044篇
神经病学   14165篇
特种医学   6171篇
外科学   25746篇
综合类   2180篇
现状与发展   2篇
一般理论   198篇
预防医学   14211篇
眼科学   3301篇
药学   11256篇
  2篇
中国医学   223篇
肿瘤学   10686篇
  2023年   902篇
  2022年   1474篇
  2021年   3493篇
  2020年   1945篇
  2019年   3139篇
  2018年   3789篇
  2017年   2722篇
  2016年   2849篇
  2015年   3421篇
  2014年   4970篇
  2013年   7271篇
  2012年   10814篇
  2011年   11391篇
  2010年   6294篇
  2009年   5732篇
  2008年   9895篇
  2007年   10495篇
  2006年   9911篇
  2005年   10031篇
  2004年   9640篇
  2003年   9042篇
  2002年   8834篇
  2001年   1446篇
  2000年   1188篇
  1999年   1606篇
  1998年   1854篇
  1997年   1497篇
  1996年   1403篇
  1995年   1365篇
  1994年   1178篇
  1993年   1121篇
  1992年   944篇
  1991年   934篇
  1990年   840篇
  1989年   799篇
  1988年   823篇
  1987年   827篇
  1986年   833篇
  1985年   899篇
  1984年   997篇
  1983年   944篇
  1982年   1213篇
  1981年   1231篇
  1980年   1044篇
  1979年   678篇
  1978年   723篇
  1977年   639篇
  1976年   551篇
  1975年   503篇
  1974年   503篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Introduction Recent reviews found problem gamblers are heterogeneous and recommended subtyping gamblers in treatment studies. Objective Review factors (stage of change, preferred gambling activity, co-occurring disorder, and temporal instability of symptoms) for subtyping by evaluating the evidence for their effects on gambling treatment. Methods Literature review, evidence grading. Results Evidence is limited that any of the reviewed factors affects gambling treatment. Substantial evidence from prospective studies and other evidence from cross-sectional studies and the strong placebo response among pathological gamblers support the temporal instability of gambling symptoms. Conclusions Multiple studies are needed to develop the evidence base needed to subtype gamblers in treatment. Changes in the diagnostic criteria of pathological gambling may be necessary, especially to specify the persistence of gambling-related symptoms.  相似文献   
92.
93.
Background: Previous studies have shown that propofol and sevoflurane enhance the function of [gamma]-aminobutyric acid type A (GABAA) receptors. However, it is not known whether these two drugs modulate the same molecular pathways. In addition, little is known about receptor function in the presence of both propofol and sevoflurane. The aim of this study was to better understand the interactions of propofol and sevoflurane with the GABAA receptor.

Methods: Wild-type [alpha]1, [beta]2, [gamma]2s GABAA receptor subunit complementary DNAs were transfected into human embryonic kidney cells grown on glass coverslips using a calcium phosphate transfection method. After transfection (36-72 h), cells were whole cell patch clamped and exposed to combinations of the following: 0.3-1,000 [mu]m [gamma]-aminobutyric acid (GABA), 0-10 [mu]m propofol, and 0-1,650 [mu]m sevoflurane. Chemicals were delivered to the cells using two 10-channel infusion pumps and a rapid solution exchanger.

Results: Both propofol and sevoflurane alone enhanced the amplitude of GABAA receptor responses to submaximal concentrations of GABA in a dose-dependent manner. The enhancement was underpinned by an increase in the apparent affinity of the receptor for GABA. Coapplication of both anesthetics further enhanced the apparent affinity of the receptor for GABA.  相似文献   

94.
95.
96.
Systems of care (SOCs) have been developed throughout the country to meet the needs of children with severe emotional disturbances (SED) and their families. In these SOCs, multiple agencies and disciplines are expected to work together with informal community supports to address families' needs (Stroul & Friedman, 1986a). A review of the literature on the impact of SOCs suggests: (a) communities' service delivery systems change; and (b) children experience modest improvements in symptomatology and functioning. At the same time, little is known about (a) which components of the SOC approach, at what levels, are necessary to impact child and family outcomes; (b) the degree to which SOCs affect other family members, beyond the target child; and (c) the impact of community contexts and supports in SOCs. Future research should improve measurement of key SOC constructs, examine the relation between specific levels of implementation and outcomes for the entire family, and investigate the impact of broader community systems and supports on families within SOCs. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 655–674, 2004.  相似文献   
97.
High levels of tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine, are present in the wound fluid of chronic nonhealing wounds. This leads to increased inflammation, cytokine expression, and ultimately results in impaired wound healing and tissue destruction. Etanercept is a recombinant fusion protein that consists of the soluble TNF receptor (p75) linked to the Fc portion of human IgG1. It is an effective inhibitor of TNF-alpha and has been shown to provide rapid and sustained improvement in rheumatoid arthritis by acting as a soluble receptor binding TNF-alpha and preventing its proinflammatory activities. Therefore, the aim of this study was to determine whether Etanercept could inhibit TNF-alpha activity in chronic wound fluid. Wound fluid was collected from the venous leg ulcers of 16 different patients. The effect of Etanercept on TNF-alpha activity was evaluated using both a TNF-alpha bioassay and an enzyme-linked immunoassay. Etanercept was found to reduce the cytotoxic effect of chronic wound fluid on L929 fibroblasts by approximately 30% and neutralized TNF-alpha binding in the enzyme-linked immunoassay by up to 80%. Direct application of Etanercept to chronic wounds may therefore reduce the inflammatory activity of TNF-alpha, which could reduce the chronicity of venous leg ulcers and thus aid in the healing of these wounds.  相似文献   
98.
99.
OBJECTIVES: This study investigates posttraumatic stress disorder (PTSD) and its associated risk factors in a random, national, Canadian sample of United Nations peacekeeping veterans with service-related disabilities. METHODS: Participants included 1016 male veterans (age < 65 years) who served in the Canadian Forces from 1990 to 1999 and were selected from a larger random sample of 1968 veterans who voluntarily and anonymously completed a general health survey conducted by Veterans Affairs Canada in 1999. Survey instruments included the PTSD Checklist-Military Version (PCL-M), Center for Epidemiological Studies-Depression Scale (CES-D), and questionnaires regarding life events during the past year, current stressors, sociodemographic characteristics, and military history. RESULTS: We found that rates of probable PTSD (PCL-M score > 50) among veterans were 10.92% for veterans deployed once and 14.84% for those deployed more than once. The rates of probable clinical depression (CES-D score > 16) were 30.35% for veterans deployed once and 32.62% for those deployed more than once. We found that, in multivariate analyses, probable PTSD rates and PTSD severity were associated with younger age, single marital status, and deployment frequency. CONCLUSIONS: PTSD is an important health concern in the veteran population. Understanding such risk factors as younger age and unmarried status can help predict morbidity among trauma-exposed veterans.  相似文献   
100.
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