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   32608篇
  免费   2535篇
  国内免费   125篇
耳鼻咽喉   292篇
儿科学   874篇
妇产科学   665篇
基础医学   3818篇
口腔科学   934篇
临床医学   3974篇
内科学   6986篇
皮肤病学   441篇
神经病学   3050篇
特种医学   1225篇
外科学   3599篇
综合类   314篇
一般理论   31篇
预防医学   3345篇
眼科学   755篇
药学   2575篇
中国医学   43篇
肿瘤学   2347篇
  2023年   257篇
  2022年   250篇
  2021年   488篇
  2020年   460篇
  2019年   501篇
  2018年   706篇
  2017年   606篇
  2016年   629篇
  2015年   714篇
  2014年   1035篇
  2013年   1574篇
  2012年   2028篇
  2011年   2152篇
  2010年   1295篇
  2009年   1409篇
  2008年   2099篇
  2007年   2300篇
  2006年   2308篇
  2005年   2225篇
  2004年   2172篇
  2003年   2054篇
  2002年   2004篇
  2001年   322篇
  2000年   223篇
  1999年   344篇
  1998年   476篇
  1997年   389篇
  1996年   368篇
  1995年   324篇
  1994年   295篇
  1993年   278篇
  1992年   162篇
  1991年   183篇
  1990年   149篇
  1989年   143篇
  1988年   130篇
  1987年   138篇
  1986年   115篇
  1985年   161篇
  1984年   214篇
  1983年   163篇
  1982年   243篇
  1981年   244篇
  1980年   232篇
  1979年   109篇
  1978年   106篇
  1977年   106篇
  1976年   82篇
  1975年   70篇
  1974年   63篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
The purpose of this study was to identify perceived barriers to independent community living and employment among clients and staff members in a transitional living facility for persons with AIDS. This qualitative study used focus groups to collect these perceptions from staff members (N = 21) and clients (N = 16). Whereas staff identified both systemic and personal barriers, clients only identified systemic barriers. These findings suggest that both clients and staff recognize the types of environmental barriers to participation that have been identified by disability scholars. The findings also underscore a consequential gap between clients' exclusive emphasis on environmental barriers and staff emphasis on clients' personal barriers that impact upon participation.  相似文献   
12.
Background  Stress gated myocardial perfusion single photon emission computed tomography (gSPECT) is increasingly used before and after intercurrent therapeutic intervention and is the basis for ongoing evaluation in the Department of Veterans Affairs clinical outcomes utilizing revascularization and aggressive drug evaluation (COURAGE) trial. Methods and Results  The COURAGE trial is a North American multicenter randomized clinical trial that enrolled 2287 patients to aggressive medical therapy vs percutaneous coronary intervention plus aggressive medical therapy. Three COURAGE nuclear substudies have been designed. The goals of substudy 0 are to examine the diagnostic accuracy of the extent and severity of inducible ischemia at baseline in COURAGE patients compared with patient symptoms and quantitative coronary angiography and to explore the relationship between inducible ischemia and the benefit from revascularization when added to medical therapy. Substudy 1 will correlate the extent and severity of provocative ischemia with the frequency, quality, and instability of recurrent symptoms in postcatheterization patients. Substudy 2 (n _ 300) will examine the usefulness of sequential gSPECT monitoring 6 to 18 months after therapeutic intervention. Together, these nuclear substudies will evaluate the role of gSPECT to determine the effectiveness of aggressive risk-factor modifications, lifestyle interventions, and anti-ischemic medical therapies with or without revascularization in reducing patients’ ischemic burdens. Conclusions  The unfolding of evidence on the application of gSPECT in trials such as COURAGE defines a new era for nuclear cardiology. We hope the evidence that emerges from the COURAGE trial will further establish the role of nuclear imaging in the evidence-based management of patients with stable coronary disease. The COURAGE trial was supported by the Cooperative Studies Program of the Department of Veterans Affairs Office of Research and Development in collaboration with the Canadian Institutes of Health Research. Unrestricted research grants were obtained from Merck & Co; Pfizer Pharmaceuticals; Bristol-Myers Squibb Medical Imaging; Astellas Pharma; Kos Pharmaceuticals; Data Scope; Astra Zeneca Pharmaceuticals; Astra-Zeneca-Canada; Schering-Plough Coorporation, Ltd; Sanofi-Aventis, Inc; First Horizon; and GE Healthcare. All industrial funding for this trial was directed through the Department of Veterans Affairs. Additional funding for this substudy was provided by grants to the Department of Veterans Affairs and Canadian Institutes of Health Research from Astellas Pharma and Bristol-Myers-Squibb Medical Imaging.  相似文献   
13.
Designed to help persons with schizophrenia to persist and perform better at job placements, the Indianapolis Vocational Intervention Program (IVIP) is a program of cognitive-behavioral group and individual interventions. While its feasibility has been previously demonstrated, it is unknown whether IVIP assists persons to achieve greater levels of participation in vocational rehabilitation and higher levels of job performance. In this study, 100 participants with schizophrenia or schizoaffective disorder were offered a six month job placement and randomized to receive IVIP (n = 50) or support services (n = 50) matched for treatment intensity. Number of hours worked was recorded weekly and job performance was assessed biweekly using the Work Behavior Inventory with raters blind to condition. t-tests revealed that participants in the IVIP group worked a significantly greater number of weeks than those in the support condition. Also, repeated measures ANOVA revealed the IVIP group worked more hours across that 26 week period as well. And with regards to work performance, repeated measures of the 56 participants who worked for at least two-thirds of the intervention revealed that participants in the IVIP group had generally better work performance than those in the support condition. Results suggest a connection between cognitive-behavioral interventions and higher levels of work performance in people with schizophrenia.  相似文献   
14.
15.
Phytochemical-mediated modulation of P-glycoprotein (P-gp) and other drug transporters may give rise to many herb-drug interactions. Serial plasma concentration-time profiles of the P-gp substrate, digoxin, were used to determine whether supplementation with goldenseal or kava kava modified P-gp activity in vivo. Twenty healthy volunteers were randomly assigned to receive a standardized goldenseal (3210 mg daily) or kava kava (1227 mg daily) supplement for 14 days, followed by a 30-day washout period. Subjects were also randomized to receive rifampin (600 mg daily, 7 days) and clarithromycin (1000 mg daily, 7 days) as positive controls for P-gp induction and inhibition, respectively. Digoxin (Lanoxin, 0.5 mg) was administered p.o. before and at the end of each supplementation and control period. Serial digoxin plasma concentrations were obtained over 24 h and analyzed by chemiluminescent immunoassay. Comparisons of area under the curve (AUC)((0-3)), AUC((0-24)), C(max,) CL/F, and elimination half-life were used to assess the effects of goldenseal, kava kava, rifampin, and clarithromycin on digoxin pharmacokinetics. Rifampin produced significant reductions (p < 0.01) in AUC((0-3)), AUC((0-24)), CL/F, t(1/2), and C(max), whereas clarithromycin increased these parameters significantly (p < 0.01). With the exception of goldenseal's effect on C(max) (14% increase), no statistically significant effects on digoxin pharmacokinetics were observed following supplementation with either goldenseal or kava kava. When compared with rifampin and clarithromycin, supplementation with these specific formulations of goldenseal or kava kava did not appear to affect digoxin pharmacokinetics, suggesting that these supplements are not potent modulators of P-gp in vivo.  相似文献   
16.
17.
18.
The functional significance of the pars tuberalis (PT) of the mammalian adenohypophysis has remained an enigma (1, 2). One view of its function is that it acts as an auxiliary gland to support the endocrine role of the pars distalis (PD) (2), as it has been shown to contain immunocytochemically identifiable thyrotrophs and gonadotrophs (1). Many of the cells of the PT are, however, ultrastructurally unique suggesting an independent function for this tissue. Our recent demonstration that the PT of the rat is a major binding site for the ligand iodomelatonin lends further support to this idea (3). We have utilized the highly specific ligand [125l]melatonin, and have demonstrated that it binds exclusively, with very high affinity, to the PT but not the PD of the adult sheep adenohypophysis. These findings support the conclusion that the PT has a distinct role in relation to melatonin action and seasonal reproduction.  相似文献   
19.
OBJECTIVE: To assess the impact of activity restriction (AR) on the incidence of preterm birth in women treated for preterm labor testing negative for fetal fibronectin (fFN). STUDY DESIGN: Women who were diagnosed with preterm labor and tocolyzed with magnesium sulfate were concurrently screened with fFN for the purpose of subsequent management. Included were consenting patients with negative fFN, gestational age 23 0/7-33 6/7 weeks, cervical dilation < or =3 cm, and minimal vaginal bleeding. Patients were randomized to AR or no AR. Primary study outcome was incidence of preterm delivery and interval from randomization to delivery. RESULTS: A total of 73 women with negative fFN were randomized (36 with AR, 37 without AR). The overall preterm birth rate was 40%, with 44.4% of patients with AR and 35.1% of patients without AR delivering preterm, p=0.478. CONCLUSION: Maternal AR did not impact pregnancy outcome. The incidence of preterm birth in symptomatic women testing fFN negative was higher than previously reported.  相似文献   
20.

Background  

Although training and education have long been accepted as integral to disaster preparedness, many currently taught practices are neither evidence-based nor standardized. The need for effective evidence-based disaster training of healthcare staff at all levels, including the development of standards and guidelines for training in the multi-disciplinary health response to major events, has been designated by the disaster response community as a high priority. We describe the application of systematic evidence-based consensus building methods to derive educational competencies and objectives in criteria-based preparedness and response relevant to all hospital healthcare workers.  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