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   65992篇
  免费   4908篇
  国内免费   151篇
耳鼻咽喉   839篇
儿科学   1819篇
妇产科学   1656篇
基础医学   10991篇
口腔科学   1715篇
临床医学   6248篇
内科学   13254篇
皮肤病学   1000篇
神经病学   6217篇
特种医学   2718篇
外国民族医学   45篇
外科学   8439篇
综合类   557篇
一般理论   86篇
预防医学   5162篇
眼科学   1279篇
药学   4753篇
中国医学   167篇
肿瘤学   4106篇
  2022年   416篇
  2021年   1089篇
  2020年   697篇
  2019年   967篇
  2018年   1189篇
  2017年   833篇
  2016年   974篇
  2015年   1175篇
  2014年   1417篇
  2013年   2440篇
  2012年   3136篇
  2011年   3255篇
  2010年   2337篇
  2009年   1966篇
  2008年   2928篇
  2007年   3065篇
  2006年   3045篇
  2005年   2889篇
  2004年   2968篇
  2003年   2687篇
  2002年   2755篇
  2001年   2260篇
  2000年   2353篇
  1999年   2044篇
  1998年   903篇
  1997年   747篇
  1996年   677篇
  1995年   701篇
  1994年   573篇
  1993年   617篇
  1992年   1470篇
  1991年   1409篇
  1990年   1344篇
  1989年   1341篇
  1988年   1108篇
  1987年   1120篇
  1986年   1061篇
  1985年   976篇
  1984年   715篇
  1983年   653篇
  1982年   461篇
  1981年   447篇
  1980年   387篇
  1979年   632篇
  1978年   381篇
  1977年   364篇
  1975年   380篇
  1974年   419篇
  1973年   357篇
  1972年   346篇
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
81.

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   
82.
With a view to the development of new controlled drug delivery systems, the formation of an interpolyelectrolyte complex (IPEC) between chitosan (CTS) and Eudragit L100 (L-100) has been studied. The structure of this IPEC is such that two maxima are observed in the curves of IPEC swelling in the media with different pH values. The release of a model drug (ibuprofen) from IPEC-based tablets is significantly retarded, and this delay can be controlled by changing the molecular weight of CTS in the IPEC composition. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 39, No. 12, pp. 44–46, December, 2005.  相似文献   
83.
The use of epidemiologic research designs and analytical methods is common in dietetics research. Food and nutrition professionals who seek to perform evidence-based practice or participate in research design, analysis, and communication need skills in the essentials of epidemiology. This is one of a series of monographs on research methodology that addresses these needs and supports the goals of the Board of Editors of the Journal of the American Dietetic Association to further enhance competency and skills. This monograph focuses on statistical approaches for univariate analyses used with the primary observational study designs associated with epidemiology. Tables illustrating the presentation and interpretation of these results are included.  相似文献   
84.
85.
86.
R Van  C C Wun  A L Morrow  L K Pickering 《JAMA》1991,265(14):1840-1844
Fecal coliform contamination of environmental surfaces and hands in the day-care center is common. This study evaluated the effect of two diaper types on fecal contamination. Ten rooms in four day-care centers containing 141 children were studied in a prospective, randomized, crossover study. A total of 2946 samples were cultured during the 9-week study. Fecal coliforms were isolated from 307 inanimate objects (15%), 73 toy balls (46%), and 131 hands (17%). The number of contaminated inanimate objects was significantly less in rooms where paper diapers were worn when compared with that in rooms where double cloth diapers with plastic overpants were worn and in rooms where clothes were worn over diapers. Inanimate object cultures had more contamination in rooms in which diarrhea had occurred. Containment of feces by overclothes and diaper type may be important in decreasing transmission of enteric pathogens in day-care environments.  相似文献   
87.
88.
89.
Temporoparietal and posterior cingulate metabolism deficits characterize patients with Alzheimer's disease (AD). A H(2)(15)O resting PET scan covariance pattern, derived by using multivariate techniques, was previously shown to discriminate 17 mild AD patients from 16 healthy controls. This AD covariance pattern revealed hypoperfusion in bilateral inferior parietal lobule and cingulate; and left middle frontal, inferior frontal, precentral, and supramarginal gyri. The AD pattern also revealed hyperperfusion in bilateral insula, lingual gyri, and cuneus; left fusiform and superior occipital gyri; and right parahippocampal gyrus and pulvinar. In an independent sample of 23 outpatients with mild cognitive impairment (MCI) followed at 6-month intervals, the AD pattern score was evaluated as a predictor of cognitive decline. In this MCI sample, an H2(15)O resting PET scan was carried out at baseline. Mean duration of follow-up was 48.8 (SD 15.5) months, during which time six of 23 MCI patients converted to AD. In generalized estimating equations (GEE) analyses, controlling for age, sex, education, and baseline neuropsychological scores, increased AD pattern score was associated with greater decline in each neuropsychological test score over time (Mini Mental State Exam, Selective Reminding Test delayed recall, Animal Naming, WAIS-R digit symbol; Ps<0.01-0.001). In summary, a resting PET covariance pattern previously reported to discriminate AD patients from control subjects was applied prospectively to an independent sample of MCI patients and found to predict cognitive decline. Independent replication in larger samples is needed before clinical application can be considered.  相似文献   
90.
The case reports of 102 patients with subdural empyema, diagnosed in the years 1935-83, were reviewed to determine the factors affecting the outcome. Statistical analysis (likelihood ratio tests with chi square approximation and logistic regression) showed that year of diagnosis (p less than 0.01) and level of consciousness at the moment of diagnosis (p less than 0.01) had a significant bearing on the chance to survive and that these same two factors (each factor p less than 0.01) and extent of subdural pus accumulation at the moment of diagnosis (p less than 0.05) had a significant bearing on the chance of survival without severe disability. Among others the duration of the disease up to the moment of diagnosis and the mode of the first surgical procedure had no significant bearing on the outcome. These results together with those in the literature are discussed and it is concluded that diagnosis and treatment before the patient lapses into stupor or coma, increases the chance of survival and that with adequate management a mortality rate of 10% or lower is to be expected.  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