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   1339篇
  免费   81篇
  国内免费   18篇
耳鼻咽喉   4篇
儿科学   70篇
妇产科学   16篇
基础医学   195篇
口腔科学   27篇
临床医学   105篇
内科学   347篇
皮肤病学   40篇
神经病学   42篇
特种医学   90篇
外科学   92篇
综合类   66篇
一般理论   1篇
预防医学   80篇
眼科学   27篇
药学   134篇
中国医学   16篇
肿瘤学   86篇
  2023年   11篇
  2022年   10篇
  2021年   28篇
  2020年   27篇
  2019年   18篇
  2018年   24篇
  2017年   13篇
  2016年   23篇
  2015年   27篇
  2014年   37篇
  2013年   47篇
  2012年   68篇
  2011年   63篇
  2010年   57篇
  2009年   34篇
  2008年   53篇
  2007年   43篇
  2006年   46篇
  2005年   34篇
  2004年   21篇
  2003年   33篇
  2002年   35篇
  2001年   32篇
  2000年   23篇
  1999年   35篇
  1998年   33篇
  1997年   20篇
  1996年   24篇
  1995年   16篇
  1994年   16篇
  1993年   12篇
  1992年   37篇
  1991年   33篇
  1990年   25篇
  1989年   51篇
  1988年   42篇
  1987年   33篇
  1986年   28篇
  1985年   29篇
  1984年   21篇
  1983年   14篇
  1982年   11篇
  1980年   8篇
  1979年   18篇
  1978年   13篇
  1977年   12篇
  1976年   12篇
  1975年   17篇
  1973年   8篇
  1972年   8篇
排序方式: 共有1438条查询结果,搜索用时 15 毫秒
91.
92.
Hemophilia A (HEMA) is an X-linked bleeding disorder caused by mutations in the factor VIII gene (F8C). Molecular genetic testing for the factor VIII gene is challenging due to its large size. Here we present results of high throughput mutation scanning based on Southern blot analysis and direct sequencing of all PCR amplified coding exons and the exon-intron boundaries of the factor VIII gene. The results of mutation analysis on 89 hemophiliac males showed presence of a disease-causing mutation in 80 individuals (90%, 95% CI of 82%-95%). Seven out of nine mutation-negative individuals were severe cases of hemophilia A with < 1% factor VIII protein in the blood. The correlation of phenotype with genotype as observed in this study was not absolute. This finding is supported by similar observations in the international database for hemophilia A mutations (HAMSTeRS). This issue raises the importance of genotypes at other loci that can act as modifiers for the phenotype. Thirty-four novel mutations and three novel substitutions for previously reported amino acid residues were identified in this series of 80 mutations. The mutations cover the full spectrum including rearrangements, deletions, frameshift, and point mutations. The novel missense mutations require careful evaluation. Prediction of a mutation as the disease-causing allele was made from the nature of the substitution and the degree of conservation of the mutated amino acid among species that have diverged in evolution. In some cases segregation analysis of the mutation with disease condition was performed when other family members were available.  相似文献   
93.
In a previous study, we showed evidence that oxidative stress induced by hydrogen peroxide (H2O2) can inhibit the release of [3H]-D-aspartate from the bovine isolated retina, in vitro. The aim of the present study was to investigate the effect of H2O2 on glutamate and glycine levels in the bovine retina and vitreous humor, ex vivo. Furthermore, we examined whether inhibition of catalase activity with 3-amino-triazole had any effect on the concentrations of these amino acids in the posterior segment of the bovine eye. Whole eye organ cultures were prepared by incubating tissues in oxygenated Krebs solution at 37 masculine C for 30 min. After incubation, H2O2 (1-100 microM) or sterile distilled water was injected intravitreally into each eye. Thirty minutes after injection, the retina and vitreous humor were removed for analysis of glutamate and glycine by high performance liquid chromatography (HPLC) with fluorescence detection. Exogenously applied H2O2 (1-100 microM) caused a concentration-related decrease in both glutamate and glycine levels in the bovine retina. Furthermore, while H2O2 (1-10 microM) caused a concentration-dependent decrease in glycine levels in the vitreous humor, it had no significant effect on glutamate levels. The catalase inhibitor, 3-amino-triazole (10 mM), caused a significant reduction in both glutamate and glycine levels in the bovine retina, ex vivo. Likewise, 3-AT caused an attenuation in both glutamate and glycine concentration in the vitreous humor. We conclude that oxidative stress induced by H2O2 can alter the release and/or availability of amino acids in the posterior segment of bovine eyes.  相似文献   
94.
Laboratory investigations are very important tools in the diagnosis of rheumatic diseases. Nowadays a large number of tests are available. The authors have discussed some important tests of value in day to day practice.  相似文献   
95.
The antineoplastic effect of Trigonella foenum graecum seed extract has been evaluated in the Ehrlich ascites carcinoma (EAC) model in Balb-C mice. Intra-peritoneal administration of the alcohol extract of the seed both before and after inoculation of EAC cell in mice produced more than 70% inhibition of tumour cell growth with respect to the control. Treatment with the extract was found to enhance both the peritoneal exudate cell and macrophage cell counts. The extract also produced a significant antiinflammatory effect. We report here the antiinflammatory and antineoplastic effects, of Trigonella foenum graecum seed extract.  相似文献   
96.
97.
Infantile hepatic hamangioendothelioma type II is similar to angiosarcoma in terms of histomorphology and behavior. Various presentations of this lesion have been reported in the literature, e.g. cases with a hepatic mass, cutaneous hemangiomas, heart failure, etc. We report on a patient, male/2 years, who had two jejunal masses and a hepatic mass accompanied by lower GI bleeding and intestinal obstruction. The two jejunal masses and the hepatic lesion were diagnosed as angiosarcoma histomorphologically (IHHE type II), and were positive for vascular markers (CD31 and CD34) on immunohistochemistry. The patient had no skin lesions. We report this case and provide a literature review because of the unusual presentation and the overall rarity of this entity.  相似文献   
98.
99.
R Ganguly  D Cameron 《Vaccine》1989,7(5):462-464
A survey of aged veterans greater than or equal to 85 years old was undertaken to determine their vaccination behaviour prior to mounting a local education campaign on influenza vaccine. A questionnaire inquiring into circumstances which may have influenced their decision to be immunized against influenza was mailed to all 300 elderly veterans (greater than or equal to 85) obtained from the register at the James A. Haley Veterans' Hospital. Ninety-two persons responded in self addressed stamped envelopes and data were analysed six months following mailing date. The most important reason for not being immunized was lack of information concerning vaccine recommendations and its availability (48%). Fear of 'shots' and side effects was the next most important reason for not taking the vaccine (19%). Amotivation and transportation difficulties played comparatively minimal roles (10%, 13%). These data suggest that health education measures may improve vaccine compliance in the elderly population who suffer from higher death rates and complications from influenza.  相似文献   
100.
Evidence is presented for the existence of 5-hydroxytryptamine (5-HT) within the phrenic nerve of the rat and its release following electrical stimulation. Contents of 5-HT and its metabolite, 5-hydroxyindoleacetic acid (5-HIAA) in the phrenic nerve and the indoleamine released into the bathing fluid were estimated fluorimetrically after isolation on Sephadex G-10 and/or solvent-solvent extraction. Bioassays of 5-HT were done on rat fundus strip. The phrenic nerve and the end-plate zone contains high levels of 5-HT (1.9 micrograms/g wet weight) and 5-HIAA (1.5 micrograms/g wet weight). The resting release of around 1 ng 5-HT/diaphragm/min was enhanced by 50% (1.5 ng 5-HT/diaphragm/min) upon supramaximal (2-4 V) electrical stimulation of 5 Hz. Phrenic nerve diaphragm prepared from the denervated and p-chlorophenylalanine (300 mg/kg/day i.p. for 3 days) treated rats failed to release 5-HT confirming the neuronal origin and the identity of the indoleamine respectively. Furthermore, methysergide, an antagonist of 5-HT in rat fundus strip, blocked the response obtained by the sample on it. A modulatory role of 5-HT in the phrenic nerve diaphragm of the rat is envisaged from the present study.  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