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   73527篇
  免费   5373篇
  国内免费   169篇
耳鼻咽喉   919篇
儿科学   2142篇
妇产科学   1837篇
基础医学   11747篇
口腔科学   1797篇
临床医学   7647篇
内科学   14298篇
皮肤病学   1057篇
神经病学   7025篇
特种医学   2876篇
外国民族医学   45篇
外科学   9219篇
综合类   678篇
一般理论   99篇
预防医学   6379篇
眼科学   1385篇
药学   5152篇
中国医学   179篇
肿瘤学   4588篇
  2022年   471篇
  2021年   1258篇
  2020年   781篇
  2019年   1191篇
  2018年   1429篇
  2017年   997篇
  2016年   1142篇
  2015年   1348篇
  2014年   1733篇
  2013年   2889篇
  2012年   3834篇
  2011年   3882篇
  2010年   2663篇
  2009年   2246篇
  2008年   3512篇
  2007年   3660篇
  2006年   3591篇
  2005年   3472篇
  2004年   3487篇
  2003年   3136篇
  2002年   3162篇
  2001年   2226篇
  2000年   2267篇
  1999年   2052篇
  1998年   973篇
  1997年   808篇
  1996年   725篇
  1995年   739篇
  1994年   646篇
  1993年   663篇
  1992年   1491篇
  1991年   1438篇
  1990年   1368篇
  1989年   1340篇
  1988年   1128篇
  1987年   1122篇
  1986年   1070篇
  1985年   975篇
  1984年   719篇
  1983年   671篇
  1982年   482篇
  1981年   463篇
  1980年   394篇
  1979年   635篇
  1978年   387篇
  1977年   364篇
  1975年   377篇
  1974年   417篇
  1973年   350篇
  1972年   344篇
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
81.
Monoamine oxidase A gene promoter (MAOA-uVNTR) and catechol-O-methyltransferase V158M (COMT-V158M) gene functional polymorphisms are reported to be associated with impulsive-aggression, but a biological intermediate effect remains to be determined. This study assessed the association of these polymorphisms with cerebrospinal fluid (CSF) monoamine metabolites as endophenotypes. Ninety-eight Caucasian psychiatric subjects were assessed for Axis I and II diagnosis. Subjects were genotyped for the functional polymorphisms, MAOA-uVNTR and COMT-V158M. CSF was obtained by lumbar puncture. Relationships of the two polymorphism to monoamine metabolites: HVA, 5-HIAA, and MHPG were examined. The higher-expressing MAOA-uVNTR genotype was associated with higher CSF-HVA levels in males only (n = 46) (195.80 pmol/ml, SD = 61.64 vs. 161.13, SD = 50.23, respectively; P = 0.042). No association was found with diagnosis. COMT-V158M had no association with CSF monoamine metabolites. The association of MAOA-uVNTR with dopaminergic activity in males is a preliminary finding that needs to be replicated in a larger sample of Caucasian males and relationships sought with clinical phenotypes. This article contains supplementary material, which may be viewed at the American Journal of Medical Genetics website at http://www.interscience.wiley.com/jpages/0148-7299:1/suppmat/index.html.  相似文献   
82.
If proven effective, vaginal microbicides and diaphragms will likely be part of a larger HIV prevention model that includes condoms and other prevention strategies. It is, therefore, important to understand how introducing new prevention methods may affect overall patterns of sexual risk behavior. Data presented were collected as part of a safety and feasibility study of ACIDFORM gel with a diaphragm among 120 women in South Africa. Interviews were administered at enrollment and months 1, 3, 5, and 6 of the trial. Focus groups were conducted at trial exit. Frequency of sex increased significantly after enrollment. This increase appears to be owing to perceived protection from HIV and greater sexual pleasure afforded by the gel. Male condom use was high overall but increased significantly from enrollment. Data suggest this is because of increased partner involvement, increased negotiating power afforded by study participation, and provision of free condoms perceived to be of high quality.  相似文献   
83.
International Journal of Clinical Pharmacy - In order to calculate the minimum sterilization process conditions to obtain the generally accepted sterility level (less than 1·10?6...  相似文献   
84.
The effects of intracerebral implants of 17 beta estradiol and cholesterol in five brain regions were tested on the duration of the dorsal immobility response in ovariectomized female rats. The dorsal immobility response was significantly prolonged by 4-hr implants of 17 beta estradiol in the dorsal striatum and nucleus accumbens, but not in the cortex, the globus pallidus, or the substantia nigra pars compacta. These data further support previous evidence that estradiol acts directly on the striatum to affect behavior in the rat.  相似文献   
85.
The morphology of neurons is an important factor for the identification and the study of the changes that occur in the nervous system during development or as a result of disease or an experimental treatment. A number of methods to describe the topological aspects of neuronal morphology is discussed. Furthermore it is illustrated how different groups of neurons can be compared. Although both topological and metrical aspects are considered in the comparative sections emphasis is put on counting instead of measuring. Our intention is to present quick and easy methods that are applicable to camera lucida drawings.  相似文献   
86.
87.
88.
The main objective of this study was to examine the psychosocial stress model developed by Taylor and Aspinwall with emotional exhaustion as the outcome variable. Respondents, 409 men and 346 women, who had a paid job for at least 20 hours per week, completed questionnaires concerning demographic variables, personality, temperament, work pressure, workload, perceived social support, appraisal, coping, and emotional exhaustion. Structural equation analyses provided only partial support for the validity of the model. First, on theoretical and statistical grounds, one more path linking external resources to social support was added. Second, contrary to expectations, coping styles did not predict emotional exhaustion. To conclude, when coping is measured retrospectively, it does not add to our understanding of emotional exhaustion. It is suggested that future studies should be longitudinal and include objective measures of stressors and psychosocial health outcomes in addition to self‐reports. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
89.
BACKGROUND: Neovascularisation at the sapheno-femoral junction (SFJ) ligation site in the groin may occur within one year after great saphenous vein (GSV) surgery. Several anatomical and prosthetic barrier techniques have been proposed to prevent this evolution. OBJECTIVE: A prospective study examined whether closing the cribriform fascia could reduce the incidence of postoperative neovascularisation in the groin. PATIENTS AND METHODS: Patients with primary varicose veins and incompetence at the level of the SFJ were included. After SFJ ligation in 235 limbs of 193 patients an anatomical barrier was constructed by closing the cribriform fascia. Postoperative duplex scanning was performed after 2 and 12 months. Results were compared with historical control groups in which either a silicone patch saphenoplasty or no barrier technique had been performed. RESULTS: After one year, 10 limbs had developed recurrent thigh varicose veins and duplex scan showed neovascularisation at the SFJ ligation site in 15 of 223 re-examined limbs (6.7%). This was comparable to the group of 191 limbs with silicone patch saphenoplasty (5.2%) (P=0.526) and superior to the group of 189 limbs without barrier (14.8%) (P<0.01). CONCLUSION: Interposition of an anatomical barrier by closing the cribriform fascia after SFJ ligation reduced ultrasound detected neovascularisation at the SFJ after one year. In primary varicose vein operations application of an anatomical barrier technique (without prosthetic patch) is an alternative option to prevent postoperative neovascularisation.  相似文献   
90.

Background  

The mitogen-activated protein kinases, MAPKs for short, constitute cascades of signalling pathways involved in the regulation of several cellular processes that include cell proliferation, differentiation and motility. They also intervene in neurological processes like fear conditioning and memory. Since little remains known about the MAPK-Activated Protein Kinase, MAPKAPK5, we constructed the first MAPKAPK knockin mouse model, using a constitutive active variant of MAPKAPK5 and analyzed the resulting mice for changes in anxiety-related behaviour.  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