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   11063篇
  免费   1080篇
  国内免费   286篇
耳鼻咽喉   24篇
儿科学   169篇
妇产科学   115篇
基础医学   2957篇
口腔科学   129篇
临床医学   648篇
内科学   1758篇
皮肤病学   81篇
神经病学   1389篇
特种医学   157篇
外国民族医学   1篇
外科学   650篇
综合类   1101篇
现状与发展   3篇
一般理论   1篇
预防医学   887篇
眼科学   98篇
药学   1120篇
  2篇
中国医学   538篇
肿瘤学   601篇
  2024年   26篇
  2023年   172篇
  2022年   168篇
  2021年   445篇
  2020年   373篇
  2019年   364篇
  2018年   363篇
  2017年   404篇
  2016年   425篇
  2015年   492篇
  2014年   634篇
  2013年   782篇
  2012年   630篇
  2011年   646篇
  2010年   580篇
  2009年   603篇
  2008年   579篇
  2007年   515篇
  2006年   464篇
  2005年   402篇
  2004年   373篇
  2003年   276篇
  2002年   242篇
  2001年   224篇
  2000年   203篇
  1999年   152篇
  1998年   160篇
  1997年   124篇
  1996年   147篇
  1995年   134篇
  1994年   96篇
  1993年   109篇
  1992年   97篇
  1991年   77篇
  1990年   70篇
  1989年   83篇
  1988年   88篇
  1987年   46篇
  1986年   63篇
  1985年   72篇
  1984年   92篇
  1983年   47篇
  1982年   77篇
  1981年   58篇
  1980年   57篇
  1979年   50篇
  1978年   34篇
  1977年   29篇
  1976年   40篇
  1973年   15篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
We compared the time course of changes in serum levels of circulating immune complexes (CICs) and of IgG antibody after sensitization of albino Lewis and pigmented Lister strain rats with uveitogenic (retinal S-antigen) and non-uveitogenic (ovalbumin) protein antigens of comparable molecular weight. Normal levels of CICs were far lower in Lewis rats in which experimental autoimmune uveoretinitis (EAU) takes the form of a severe panuveitis, than in Lister rats, in which the disease is mild, focal, confined to the posterior segment, and of lower incidence. After sensitization with either S-antigen or ovalbumin, polyethylene-glycol-precipitable CIC (PEG-CIC) peaked and fell as IgG antibody levels rose in both rat strains. However, peak levels of PEG-CIC were lower and subsequent IgG antibody levels were higher in the Lewis strain than in the less susceptible Lister strain. In both strains of rat these linked PEG-CIC/IgG antibody responses occurred earlier after sensitization with uveitogenic (S-) antigen than with ovalbumin, whether or not individual S-antigen-sensitized Lister rats developed EAU. In contrast, complement-binding CIC rose substantially only in those rats of both strains displaying EAU in response to S-antigen and not in response to ovalbumin. We suggest that immune complex (idiotypic) regulation of IgG antibody responses may be more readily perturbed by a pathogenic autoantigen (S-antigen) than by a bland antigen (ovalbumin). We also suggest that differences between the balance of regulatory and pathogenic CIC responses to uveitogenic retinal antigen may underlie or reflect strain differences in susceptibility to and severity of EAU.  相似文献   
92.
The PEL1/PGS1 gene of the yeast Saccharomyces cerevisiae is essential for the viability of rho /rho° mutants and the normal cardiolipin content of cells. The PEL1-GFP fusion gene has been found to complement the pel1/pgs1 mutation and its fluorescent protein was localized to mitochondria similarly to the β-galactosidase activity of a protein encoded by the PEL1-lacZ fusion gene. The expression of the PEL1-lacZ reporter gene was repressed in cells grown in the presence of inositol and choline, reduced in the ino2 and ino4 strains, but constitutive in the opi1 null-mutant strain. The results demonstrate that Pel1p, playing a vital role in cells impaired in the mitochondrial DNA, is localized in the mitochondria and expressed in response to inositol and choline. Received: 15 June / 15 July 1998  相似文献   
93.
Salivary thermolytic mechanism (weight of salivary glands, effect of desalivation on water intake and body temperature, grooming activity) as well as escape behaviour and reaction to heat pain were studied in capsaicin-desensitized and control rats exposed to various warm ambient temperatures. Body temperature of the desensitized rats increased more than the controls at all the ambient temperatures studied (32, 34 and 36°C); however, significant differences in the mechanism of salivary cooling were obtained only at 34 and 36°C. Central impairment of saliva spreading in desensitized rats seems evident. Complete surgical desalivation did not increase hyperthermia of control and desensitized animals in warm environments. Therefore other mechanisms, primarily vasodilatatory, must also be involved in the rat's thermolytic normal response. Although desensitized rats did not show a tendency to escape from the warm environment their response to heat pain was normal. In conclusion, it is suggested that heat perception in desensitized animals is impaired; however, the existence of some capsaicin-insensitive thermolytic mechanisms (prone extension of the body) cannot be excluded.Supported by the Scientific Research Council, Ministry of Health, Hungary /4-05-0303-04-2/0/ and MTA-OM-MÉM-EÜM 70.211/79  相似文献   
94.
应用mRNA麦胚无细胞体外转译体系,动态地观察了人参三醇皂甙(PTGS)对人淋巴结细胞IL-5基因表达的促进效应。结果表明,PTGS可以明显促进PHA活化人淋巴结细胞分泌IL-5,最大促进效应可达66.67%。PTGS+PHA共刺激后人淋巴结细胞浆IL-5 mRNA转译IL-5的量明显高于单纯PHA组,最大促进效应40%。上述结果首次证明PTGS对IL-5的促诱生效应是通过调节IL-5基因表达而实现的。  相似文献   
95.
96.
Gardner LM  Spyroglou L  O'Hehir RE  Rolland JM 《Allergy》2004,59(12):1308-1317
BACKGROUND: Clinically effective allergen-specific immunotherapy correlates with decreased circulating allergen-specific IL-4+ T cells but increased IFN-gamma+ cells at sites of allergen challenge. Whether immunotherapy promotes trafficking of IFN-gamma+ T cells to peripheral tissues is unknown. As aeroallergen is administered at higher concentrations during immunotherapy than those encountered naturally, the effect of allergen concentration on adhesion molecule (CD62L and CD49d) and chemokine receptor (CCR3 and CCR5) expression by peripheral-blood T cells was analysed in parallel with cytokine production. METHODS: House dust mite-allergic donor peripheral blood mononuclear cells were cultured for 14 days with different allergen concentrations. Cytokine profiles of were analysed by flow cytometry. RESULTS: Cultures stimulated with 100 microg/ml house dust mite extract compared with 1 microg/ml had increased proportions and numbers of CD62Llo, CD49dhi or CCR5+ T cells expressing IFN-gamma. CCR3-positive CD4+ and CD8+ T cell numbers were very low and did not differ between cultures. In contrast the proportions of 'peripheral tissue trafficking' CD4+ T cells expressing IL-4 were decreased in cultures stimulated with high in comparison with low allergen concentration. CONCLUSION: These results indicate the importance of achieving high allergen doses during immunotherapy to promote IFN-gamma production and expression of a 'peripheral tissue trafficking' phenotype by allergen-specific CD4+ and CD8+ T cells. The net change in cytokine milieu at sites of allergen encounter would then down-regulate clinical manifestations of allergic disease.  相似文献   
97.
Body weight and food intake of lean and obese, male and female Osborne-Mendel rats following treadmill exercise were compared. Rats were assigned, separately by sex, to one of three diet groups; Group 1 was fed a low fat (10%) diet throughout the study, Group 2 was fed a high fat (55%) diet for 16 weeks and then switched to the low fat diet 1 week prior to exercise, and Group 3 was fed the high fat diet throughout the study. To control for differences in work output between the leanest and heaviest animals, exercise intensity was adjusted across groups such that all exercised rats had equivalent energy expenditure. After a 3 day training period, the exercise was successively increased over 8 days until a work output of 374.9J was reached. Relative to their respective controls, obese exercised males showed a reduction in body weight but no change in food intake. In contrast, exercised females showed no change in body weight or food intake, regardless of dietary condition.  相似文献   
98.
99.
目的 研究探讨青年士兵不平衡心理的特点及其规律,为加强青年士兵心理疏导和行为引导提供参考.方法 对济南军区某部939名青年士兵进行心理问卷调查、召开座谈会和个别交谈等.结果 在青年士兵中几乎每个人都不同程度有过不平衡的心理体验及反应.结论 加强对青年士兵不平衡心理的疏导与调节,有助于培养其健全的人格和健康的心理.  相似文献   
100.
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