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   11295篇
  免费   389篇
  国内免费   44篇
耳鼻咽喉   211篇
儿科学   190篇
妇产科学   295篇
基础医学   2163篇
口腔科学   216篇
临床医学   580篇
内科学   1165篇
皮肤病学   410篇
神经病学   873篇
特种医学   1580篇
外科学   1639篇
综合类   50篇
预防医学   770篇
眼科学   113篇
药学   1071篇
中国医学   90篇
肿瘤学   312篇
  2023年   41篇
  2022年   34篇
  2021年   73篇
  2020年   56篇
  2019年   75篇
  2018年   220篇
  2017年   145篇
  2016年   196篇
  2015年   133篇
  2014年   245篇
  2013年   385篇
  2012年   744篇
  2011年   1080篇
  2010年   482篇
  2009年   174篇
  2008年   795篇
  2007年   971篇
  2006年   951篇
  2005年   767篇
  2004年   686篇
  2003年   696篇
  2002年   595篇
  2001年   377篇
  2000年   490篇
  1999年   271篇
  1998年   79篇
  1997年   57篇
  1996年   41篇
  1995年   46篇
  1994年   27篇
  1993年   25篇
  1992年   34篇
  1991年   26篇
  1990年   34篇
  1989年   24篇
  1988年   28篇
  1987年   22篇
  1986年   21篇
  1985年   32篇
  1984年   24篇
  1983年   25篇
  1982年   29篇
  1981年   30篇
  1980年   30篇
  1979年   30篇
  1978年   29篇
  1976年   22篇
  1975年   26篇
  1974年   22篇
  1973年   22篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
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   
73.
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   
74.
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   
75.
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   
76.
77.
78.
Cytokines in patients with lung cancer   总被引:5,自引:0,他引:5  
Lung cancer is one of the most common malignant diseases and is amongst the leading causes of death. Cell-mediated immune response and cytokines could play an important role in antitumour immunity. The aim of the study was to evaluate the cytokines', tumour necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and IL-6, releasing capacity in patients with lung carcinoma and benign lung disease. A group of 41 patients were tested for the production of TNF-alpha, IL-1beta and IL-6 in bronchoalveolar lavage (BAL) and blood. The levels of cytokines in the lung cancer patients were: (1) in BAL - IL-6, 173 +/- 85 pg/ml; TNF-alpha, 170 +/- 116 pg/ml; and IL-1beta, 473 +/- 440 pg/ml; (2) in the blood - IL-6, 197 +/- 53 pg/ml; TNF-alpha, 311 +/- 202 pg/ml; and IL-1beta, 915 +/- 239 pg/ml. Alveolar macrophages of the patients with a lung cancer secreted significantly more cytokines, IL-6 (P = 0.0004) and IL-1beta (P = 0.0047), than alveolar macrophages of the patients with a nonmalignant lung cancer. However, significantly lower levels of cytokine production by the BAL cells were found in patients with small cell lung cancer. This production decreased further in phase IV of nonsmall cell lung cancer.  相似文献   
79.
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   
80.
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