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   13718篇
  免费   494篇
  国内免费   49篇
耳鼻咽喉   224篇
儿科学   250篇
妇产科学   355篇
基础医学   2593篇
口腔科学   262篇
临床医学   779篇
内科学   1690篇
皮肤病学   460篇
神经病学   1158篇
特种医学   1615篇
外科学   1620篇
综合类   65篇
预防医学   995篇
眼科学   146篇
药学   1438篇
中国医学   98篇
肿瘤学   513篇
  2023年   81篇
  2022年   204篇
  2021年   312篇
  2020年   130篇
  2019年   196篇
  2018年   330篇
  2017年   235篇
  2016年   294篇
  2015年   230篇
  2014年   363篇
  2013年   551篇
  2012年   936篇
  2011年   1254篇
  2010年   586篇
  2009年   272篇
  2008年   899篇
  2007年   1100篇
  2006年   1076篇
  2005年   866篇
  2004年   773篇
  2003年   746篇
  2002年   644篇
  2001年   378篇
  2000年   484篇
  1999年   269篇
  1998年   80篇
  1997年   53篇
  1996年   38篇
  1995年   49篇
  1994年   24篇
  1992年   24篇
  1991年   26篇
  1990年   33篇
  1989年   28篇
  1988年   29篇
  1987年   21篇
  1986年   27篇
  1985年   33篇
  1984年   23篇
  1983年   22篇
  1982年   30篇
  1981年   29篇
  1980年   31篇
  1979年   29篇
  1978年   29篇
  1976年   22篇
  1975年   31篇
  1974年   20篇
  1973年   20篇
  1967年   20篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
The objective of the present study was to investigate the relevance of peripheral macrophage activity for the susceptibility to the induction of experimental allergic encephalomyelitis (EAE). Rats of EAE-susceptible Dark Agouti and EAEresistant Albino Oxford strain were immunized with guinea pig spinal cord homogenate (DAGPSC and AOGPSC), while non-immunized rats served as controls (DANIM, AONIM). On day 15 after immunization rats were sacrificed and their peritoneal macrophages tested for adherence capacity, zymosan phagocytosis and respiratory burst. Macrophages from AONIM rats exhibited lower adherence capacity and higher phagocytosis and H2O2 production when compared to macrophages from DANIM rats. Immunization with GPSC decreased adherence and phagocytosis and increased H2O2 production in macrophages from AO rats, but did not influence these activities in macrophages from DA rats. The results from the present study suggest that inflammatory activities of macrophages from AO rats could be considered as regulatory mechanisms connected with the resistance to EAE induction.  相似文献   
42.
1. The properities of inputs from the horizontal semi-circular canal to neurones of the medial vestibular nucleus have been studied intracellularly in the unanaesthetized encéphale isolé cat. 2. Secondary neurones of the bestibulo-abducens reflex arc were identified by their orthodromic response to labyrinthine stimulation and by antidromic excitation from the contralateral abducens nucleus. 3. The responses of medial vestibular cells receiving only labyrinthine in puts are also described. These were seen to be predominantly excitatory though IPSPs were observed in a few cases. 4. Identified vestibular neurones were intracellularly injected with procion yellow and showed different morphological characteristics correlated with function.  相似文献   
43.
Immunoglobulin A and G (IgA, IgG) serum concentrations were detected in children with nonallergic/intrinsic (36 children) or allergic/extrinsic asthma (43 children) and in age-matching control children (40 children). Asthmatic children with allergic asthma had lower IgA (1.36+/-0.54 g/L) and higher IgG (10.48+/-2.77 g/L) levels than the age-matching control children group (1.63+/-0.69 vs. 9.01+/-2.32 g/L). Children with nonallergic/intrinsic asthma had lower IgA (1.03+/-0.41 g/L) ( p = 0.004) and IgG (8.38+/-1.93 g/L) (p = 0.001) levels than the allergic/extrinsic asthma group (1.36+/-0.54 vs. 10.48+/-2.77 g/L). Low IgA levels were found in children with nonallergic/intrinsic asthma and high IgG levels were found in those children with allergic/extrinsic childhood asthma. The hypothesis is that the increased incidence of asthma in the population may be caused by a decrease in childhood infections (hygiene hypothesis). Frequent infections in early life boost the immune system, stimulating Th1-type response in young children and reducing the risk of atopic diseases. Our hypothesis is that low IgA (and/or IgG) levels in our patients might be responsible for infection development among those children with nonallergic/intrinsic asthma. These infections stimulate the normal development of immune system in young children, reducing risk of atopy, so that those children do not get allergic/extrinsic childhood asthma. Intrinsic childhood asthma=nonallergic (nonatopic) childhood asthma. Extrinsic childhood asthma=allergic (atopic) childhood asthma.  相似文献   
44.
A sensitive and stereospecific GC method was developed for the analysis of R- and S-enantiomers of mandelic acid (MA) in urine, using a chiral CP Chirasil-Dex-CB column. The enantiomers of MA were derivatised with isopropanol into their corresponding isopropyl esters and determined either directly with flame ionisation detection (FID) or after subsequent derivatisation of a hydroxy group with pentafluoropropionic anhydride with electron-capture detection (ECD). Both derivatisation steps proceeded with negligible inversion of enantiomers (<1%). The limit of detection of the FID determination was 8 and 5 mg/l for R-MA and S-MA, respectively and of the ECD determination 1 mg/l for both enantiomers. Repeatability (within-day precision) and reproducibility (day-to-day precision) was for both enantiomers below 7.5% for the FID and below 5.8% for the ECD analysis. The method was applied to urine of volunteers exposed to 105 and 420 mg styrene/m3 air. In the urine of the exposed volunteers, the S-enantiomer showed higher excretion compared to that of the R-enantiomer, with marked interindividual differences in excretion of both enantiomers.  相似文献   
45.
46.
47.
This study evaluated a breast self-examination intervention to increase phase-specific self-efficacy and positive outcome expectancies. The role of social cognitive predictors in the process of behavior change was investigated. Using cluster randomization, participants were assigned to an intervention (n = 244) or to a control (n = 173) group. Controls were measured twice, with 13 weeks between the assessments. Respondents from the intervention group received the intervention before the 1st measurement. The increase in the number of self-examination components was significantly higher in the intervention group than among controls. Women who had never performed self-examinations before the intervention, as well as those who did it irregularly or incompletely, changed their behavior significantly. Results of structural equation modeling for a 2-group model showed that phase-specific self-efficacy was a significant predictor of intention, planning, and behavior change in the intervention group. In the control group, these relations were weaker or remained nonsignificant. Social cognitive variables measured in this study explained 15% of variance of behavior change in the control group and 29% of breast self-examination change in the intervention group.  相似文献   
48.
We report on a case of a 40-year-old male patient who underwent a gastrectomy because of a biopsy-proven large B-cell lymphoma of the stomach. On surgery, a nodule in the spleen also was noted. Grossly and microscopically, the two lesions were different: the tumor of the stomach appeared white-gray on the cut surface and was a centroblastic variant of diffuse large B-cell lymphoma. Histologically, one perigastric lymph node was involved. Grossly, the splenic nodule was gray-yellow and had a histological appearance of an inflammatory myofibroblastic tumor (IMT). The association between malignant tumor and IMT is rare. In such an association, the latter lesion most often has been reported in the spleen. As EBV may be involved in the genesis of both lymphoma and IMT, we tested both lesions for its presence using in situ hybridization, but the tests were negative. It remains to be verified whether the association between lymphoma and IMT is more than fortuitous.  相似文献   
49.
50.
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