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   179103篇
  免费   7882篇
  国内免费   162篇
  2021年   1534篇
  2020年   2827篇
  2019年   3501篇
  2018年   3668篇
  2017年   4103篇
  2016年   4745篇
  2015年   3985篇
  2014年   4868篇
  2013年   23884篇
  2012年   4929篇
  2011年   4025篇
  2010年   4093篇
  2009年   4900篇
  2008年   4233篇
  2007年   3832篇
  2006年   4336篇
  2005年   4277篇
  2004年   3732篇
  2003年   3347篇
  2002年   3170篇
  2001年   3420篇
  2000年   3255篇
  1999年   3262篇
  1998年   2866篇
  1997年   2686篇
  1996年   2599篇
  1995年   2469篇
  1994年   2402篇
  1993年   2353篇
  1992年   2710篇
  1991年   2505篇
  1990年   2399篇
  1989年   2274篇
  1988年   2267篇
  1987年   2272篇
  1986年   2247篇
  1985年   2425篇
  1984年   2566篇
  1983年   2356篇
  1982年   2388篇
  1981年   2352篇
  1980年   2217篇
  1979年   2269篇
  1978年   2218篇
  1977年   2167篇
  1976年   1979篇
  1975年   2049篇
  1974年   2110篇
  1973年   1995篇
  1972年   1544篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
171.
OBJECTIVE: Compare the efficacy of a multicomponent social support intervention to standard-of-care counseling on medication adherence among HIV-infected patients initiating antiretroviral therapy. DESIGN: Randomized controlled trial. Generalized estimating equations tested for differences in the percentage of participants achieving 90% adherence. MAIN OUTCOME MEASURES: Pill-taking, electronically monitored over 6 consecutive months; plasma viral load (VL), assessed at 3 and 6 months following initiation of therapy. RESULTS: Of 226 participants who were randomized and began the trial, 87 (38%) were lost to the study by 6 months. The proportion of adherent participants declined steadily over time, with no time by group interaction. Sustained adherence was associated with increased odds of achieving an undetectable VL (OR=1.78; 95% CI=1.01, 3.13). In intention-to-treat analyses, a larger proportion of the intervention group than the control group was adherent (40.15% vs. 27.59%, p=.02) and achieved an undetectable VL p=.04). However, the majority of participants who remained on study experienced some reduction in VL (>or=1-log drop or undetectable), regardless of experimental condition. CONCLUSION: The multicomponent social support intervention significantly improved medication adherence over standard-of-care counseling; evidence for improved virologic outcomes was inconsistent. Early discontinuation of care and treatment may be a greater threat to the health of HIV patients than imperfect medication-taking.  相似文献   
172.
A series of four spatial localization experiments is reported that examined the effects of display duration and presentation mode on positive and negative priming using an attended-repetition and an ignored-repetition paradigm, respectively. Experiment 1 showed larger positive priming with response-dependent than with 150 ms display durations while negative priming remained unaffected. Experiments 2-4 were performed to further elucidate the effects of prime-probe durations. Data suggest largely independent effects of prime and probe duration on priming effects. Manipulation of prime duration affected facilitation due to repetition of the prime distractor location as well as inhibitory effects associated with ignored repetition. Furthermore, anticipated probe duration modulated the effectiveness of inhibition of return. Findings are discussed within a framework proposing two major components of priming effects—a stimulus-driven or automatic component, and a strategic component related to the participant's expectations towards the probe.  相似文献   
173.
In this study, we explored the structure of pupils’ creativity in primary education following the Amusement Park Theory, by investigating undiscovered linkages between the domains of writing, mathematics, and drawing. More specifically, we examined: (a) whether some domains and general thematic areas are more closely related to each other than to others, (b) whether literacy and mathematical ability are specific underlying traits of creativity in writing and mathematics, respectively, and (c) whether intelligence and divergent thinking are related to creativity in all domains. The sample consisted of 331 Dutch 4th grade pupils. For each research question, a model was analyzed using structural equation modeling. We found creativity in mathematics and creativity in writing to be most similar, followed by creativity in mathematics and creativity in drawing, with creativity in writing and creativity in drawing being least similar. Additionally, we found evidence for several underlying traits (i.e., literacy ability and mathematical ability) and initial requirements of creativity (i.e., intelligence and divergent thinking), none of which were important for creativity in only one domain, and of which only intelligence was important for creativity in all domains. Herewith, our study provides insights regarding the complexity of the structure of creativity in primary education.  相似文献   
174.
175.
The authors used recursive partitioning methods to identify combinations of baseline characteristics that predict 2-year physical activity success in each of 3 physical activity interventions delivered in the multisite Activity Counseling Trial. The sample consisted of 874 initially sedentary primary care patients, ages 35-75 years, who were at risk for cardiovascular disease. Predictors of 2-year success were specific to each intervention and represented a range of domains, including physiological, demographic, psychosocial, health-related, and environmental variables. The results indicate how specific patient subgroups (e.g., obese, unfit individuals; high-income individuals in stable health) may respond differently to varying levels and amounts of professional assistance and support. The methods used provide a practical first step toward identifying clinically meaningful patient subgroups for further systematic investigation.  相似文献   
176.
177.
This study evaluated cardiovascular responses (CVR) to an active speech task with blatantly discriminatory (BRC) versus neutral (NRC) stimuli and an anger recall task in a sample of Black men (N = 73; age 18 to 47). Diastolic blood pressure scores were higher for NRC versus BRC stimuli during anger recall (p = .05). Moreover, persons in the NRC group who perceived high levels of racism (vs. no racism or BRC group) during active speech showed larger increases in blood pressure across postspeech rest, anger recall, and subsequent rest (p = .03). The notable elevation in CVR in response to an ambiguous event extends current models of racism suggesting that subtle racism is a psychosocial stressor that erodes health through chronically elevated CVR.  相似文献   
178.
179.
180.
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