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   6569篇
  免费   743篇
  国内免费   14篇
耳鼻咽喉   70篇
儿科学   250篇
妇产科学   200篇
基础医学   1102篇
口腔科学   130篇
临床医学   678篇
内科学   1287篇
皮肤病学   110篇
神经病学   711篇
特种医学   144篇
外科学   841篇
综合类   140篇
一般理论   6篇
预防医学   667篇
眼科学   146篇
药学   510篇
中国医学   7篇
肿瘤学   327篇
  2022年   44篇
  2021年   102篇
  2020年   53篇
  2019年   115篇
  2018年   120篇
  2017年   99篇
  2016年   91篇
  2015年   104篇
  2014年   158篇
  2013年   224篇
  2012年   365篇
  2011年   358篇
  2010年   181篇
  2009年   165篇
  2008年   278篇
  2007年   337篇
  2006年   308篇
  2005年   248篇
  2004年   277篇
  2003年   232篇
  2002年   250篇
  2001年   212篇
  2000年   161篇
  1999年   209篇
  1998年   88篇
  1997年   63篇
  1996年   62篇
  1995年   68篇
  1994年   63篇
  1993年   70篇
  1992年   135篇
  1991年   113篇
  1990年   106篇
  1989年   113篇
  1988年   121篇
  1987年   128篇
  1986年   133篇
  1985年   126篇
  1984年   84篇
  1983年   86篇
  1982年   53篇
  1981年   70篇
  1980年   62篇
  1979年   94篇
  1978年   62篇
  1977年   57篇
  1976年   52篇
  1974年   58篇
  1973年   69篇
  1972年   57篇
排序方式: 共有7326条查询结果,搜索用时 546 毫秒
121.
122.
123.
124.
125.
126.
127.
A 2 × 2 experiment was conducted, where participants watched anti-tobacco messages that varied in deception (content portraying tobacco companies as dishonest) and disgust (negative graphic images) content. Psychophysiological measures, self-report, and a recognition test were used to test hypotheses generated from the motivated cognition framework. The results of this study indicate that messages containing both deception and disgust push viewers into a cascade of defensive responses reflected by increased self-reported unpleasantness, reduced resources allocated to encoding, worsened recognition memory, and dampened emotional responses compared to messages depicting one attribute or neither. Findings from this study demonstrate the value of applying a motivated cognition theoretical framework in research on responses to emotional content in health messages and support previous research on defensive processing and message design of anti-tobacco messages.  相似文献   
128.
Protein arginylation by arginyl–transfer RNA protein transferase (ATE1) is emerging as a regulator protein function that is reminiscent of phosphorylation. For example, arginylation of β-actin has been found to regulate lamellipodial formation at the leading edge in fibroblasts. This finding suggests that similar functions of β-actin in other cell types may also require arginylation. Here, we have tested the hypothesis that ATE1 regulates the cytoskeletal dynamics essential for in vivo platelet adhesion and thrombus formation. To test this hypothesis, we generated conditional knockout mice specifically lacking ATE1 in their platelets and in their megakaryocytes and analyzed the role of arginylation during platelet activation. Surprisingly, rather than finding an impairment of the actin cytoskeleton structure and its rearrangement during platelet activation, we observed that the platelet-specific ATE1 knockout led to enhanced clot retraction and in vivo thrombus formation. This effect might be regulated by myosin II contractility since it was accompanied by enhanced phosphorylation of the myosin regulatory light chain on Ser19, which is an event that activates myosin in vivo. Furthermore, ATE1 and myosin co-immunoprecipitate from platelet lysates. This finding suggests that these proteins directly interact within platelets. These results provide the first evidence that arginylation is involved in phosphorylation-dependent protein regulation, and that arginylation affects myosin function in platelets during clot retraction.  相似文献   
129.
Background: Although opiate use may be associated with posttraumatic stress disorder (PTSD), it is not clear whether PTSD is associated with retention in methadone maintenance. Objectives: To evaluate among those receiving methadone maintenance at an urban methadone maintenance clinic the frequency of life‐time traumatic experiences, the predictors and prevalence of current PTSD, and whether PTSD affects retention at 1 year. Methods: Eighty‐nine people participated in the study. The Post Traumatic Diagnostic Scale was used to determine the prevalence of PTSD. The Life Stressor Checklist Revised was used to evaluate trauma history. Logistic regression analyses examined associations between demographic characteristics, substance use, trauma‐related variables, and PTSD. Similar logistic regression analyses were used to examine retention in methadone maintenance at 1 year. Results: The mean number of reported lifetime stressful events was 8.0 (SD = 3.7). Twenty‐seven percent were diagnosed with PTSD. Nearly 92% of those with PTSD had co‐occurring depressive symptoms. Female gender (adjusted odds ratio [AOR][95% CI]; 3.89 [1.07–14.01]), number of traumatic events (AOR [95% CI]; 1.34 [1.13–1.61]), and less education (AOR [95% CI]; 4.13 [1.14–14.98]) were significantly associated with PTSD. Those with a toxicology positive screen were 80% less likely to remaine in methadone maintenance at 1 year (OR [95% CI]; 0.20 [0.07–0.52]). PTSD diagnosis was not significantly associated with treatment retention at 1 year (OR [95% CI]; 0.61 [0.23–1.64]). Conclusions and Scientific Significance: Future studies are needed to determine if treatment of PTSD that is integrated into methadone maintenance programs may impact continued substance abuse use and thereby improve retention in care. (Am J Addict 2012;21:524–530)  相似文献   
130.
Using an iterative structure–activity relationship driven approach, we identified a CNS-penetrant 5-(trifluoromethyl)-1,2,4-oxadiazole (TFMO, 12) with a pharmacokinetic profile suitable for probing class IIa histone deacetylase (HDAC) inhibition in vivo. Given the lack of understanding of endogenous class IIa HDAC substrates, we developed a surrogate readout to measure compound effects in vivo, by exploiting the >100-fold selectivity compound 12 exhibits over class I/IIb HDACs. We achieved adequate brain exposure with compound 12 in mice to estimate a class I/IIb deacetylation EC50, using class I substrate H4K12 acetylation and global acetylation levels as a pharmacodynamic readout. We observed excellent correlation between the compound 12 in vivo pharmacodynamic response and in vitro class I/IIb cellular activity. Applying the same relationship to class IIa HDAC inhibition, we estimated the compound 12 dose required to inhibit class IIa HDAC activity, for use in preclinical models of Huntington’s disease.  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