全文获取类型
收费全文 | 28617篇 |
免费 | 1708篇 |
国内免费 | 848篇 |
专业分类
耳鼻咽喉 | 179篇 |
儿科学 | 1101篇 |
妇产科学 | 533篇 |
基础医学 | 4205篇 |
口腔科学 | 469篇 |
临床医学 | 1695篇 |
内科学 | 5433篇 |
皮肤病学 | 518篇 |
神经病学 | 1608篇 |
特种医学 | 438篇 |
外国民族医学 | 5篇 |
外科学 | 2921篇 |
综合类 | 3203篇 |
预防医学 | 2689篇 |
眼科学 | 283篇 |
药学 | 3332篇 |
4篇 | |
中国医学 | 826篇 |
肿瘤学 | 1731篇 |
出版年
2023年 | 244篇 |
2022年 | 576篇 |
2021年 | 849篇 |
2020年 | 713篇 |
2019年 | 1252篇 |
2018年 | 1160篇 |
2017年 | 909篇 |
2016年 | 792篇 |
2015年 | 820篇 |
2014年 | 1465篇 |
2013年 | 1576篇 |
2012年 | 1300篇 |
2011年 | 1472篇 |
2010年 | 1152篇 |
2009年 | 1220篇 |
2008年 | 1176篇 |
2007年 | 1239篇 |
2006年 | 1125篇 |
2005年 | 999篇 |
2004年 | 923篇 |
2003年 | 823篇 |
2002年 | 697篇 |
2001年 | 656篇 |
2000年 | 492篇 |
1999年 | 467篇 |
1998年 | 414篇 |
1997年 | 372篇 |
1996年 | 327篇 |
1995年 | 305篇 |
1994年 | 243篇 |
1993年 | 174篇 |
1992年 | 184篇 |
1991年 | 154篇 |
1990年 | 143篇 |
1989年 | 110篇 |
1988年 | 121篇 |
1987年 | 99篇 |
1985年 | 393篇 |
1984年 | 555篇 |
1983年 | 386篇 |
1982年 | 432篇 |
1981年 | 407篇 |
1980年 | 330篇 |
1979年 | 308篇 |
1978年 | 278篇 |
1977年 | 225篇 |
1976年 | 292篇 |
1975年 | 218篇 |
1974年 | 204篇 |
1973年 | 198篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
191.
CrossingEscherichia
Coli K12 Hfr AB313 with an enteropathogenic strain ofE.
coli of the serological group 0124 yielded recombinants which had lost their invasiveness. The loss of invasiveness of these recombinants was not due to the acquisition of genes controlling resistance to streptomycin.I. P. Pavlov First Leningrad Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR N. N. Zhukov-Verezhnikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 9, pp. 1144–1145, September, 1976. 相似文献
192.
193.
The major outer membrane protein (protein I) has been isolated from Neisseria gonorrhoeae strain P9 in an immunologically reactive form. Membranes were sequentially extracted with the detergents sodium cholate and Empigen BB. Protein I was enriched in the Empigen-soluble fraction and was separated from other proteins and lipopolysaccharide by gel filtration chromatography on Sephadex G-200. The purified protein retained its antigenic activity with antiserum raised against the unfractionated outer membrane complex. 相似文献
194.
In a study of 70 patients with asthma, rhinitis, and eczema, those giving a definite history of allergic reactions to egg more frequently showed positive skin tests to egg extracts (p = less than 0.003), the wheal diameters of which were significantly larger (p = less than 0.01) than in patients with only a possible or no such history. Patients with a definite history of egg allergy had significantly higher levels of specific IgE antibody against egg yolk, egg white, and allantoic fluid than patients in the other two groups (p = less than 0.005). Seven patients, all of whom had given a definite history of allergy to egg, were found to have positive skin prick tests to influenza vaccine, at the concentration used in medical practice. Two of these patients had previously been given influenza vaccine and both had developed adverse reactions. Of the 22 patients giving a definite history of allergy to egg, the 7 (35 per cent) with positive skin tests to influenza vaccine had significantly larger skin tests and higher levels of specific IgE antibody to the egg extracts than the group as a whole (p = less than 0.001). Allergic reactions to influenza vaccine are likely to occur in patients who have a definite history of allergy to egg and large skin prick test reactions or high levels of specific IgE antibody to egg extracts. Those at risk can best be identified by skin prick testing with egg extracts and undiluted influenza vaccine. 相似文献
195.
O. V. Bukharin Yu. A. Brudastov V. A. Gritsenko D. G. Deryabin 《Bulletin of experimental biology and medicine》1996,121(2):160-162
A relationship is found between the resistance ofEscherichia coli, Staphylococcus aureus, andStaphylococcus epidermidis to human serum and whole blood and their ability to inactivate the factors of natural antiinfectious resistance (lysozyme,
complement, immunoglobulins, and a bactericidal fraction of leukocytic interferon).
Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N
o
2, pp. 174–176, February, 1996 相似文献
196.
D G Haegert 《Journal of immunological methods》1985,82(2):261-266
Under optimal test conditions significantly more freshly isolated human T cells reacted with OKT4, OKT8, OKM1 and OKB7 monoclonal antibodies (Mabs) in the indirect antiglobulin rosetting reaction (IARR) than by indirect immunofluorescence. Rabbit erythrocytes (E) coated with anti-mouse immunoglobulin were more sensitive indicator cells in the IARR than similarly coated sheep E. Treatment of T cells with neuraminidase further enhanced T cell reactivity in the IARR with each Mab so that an average of 60% or more of T cells were T4+, T8+ and M1+ and at least 40% had the T4+ T8+ phenotype. The various findings suggest that the rosette assay detects determinants on T cells that are expressed below the detection threshold of immunofluorescence. Moreover, these findings indicate that the cellular specificities of a particular Mab may change when one assay system is substituted for another or when the protocol of a particular assay is altered. 相似文献
197.
多发性硬化(multiplesclerosis,MS)的病因及发病机制至今未明。目前认为 ,主要是由其T细胞介导而致中枢神经系统炎性脱髓鞘的自身免疫性疾病[1] 。由于可溶性E选择素 (又称sCD6 2E)可介导白细胞 (中性粒、单核细胞及CD4 + 记忆性T细胞)在内皮细胞表面最初的滞留和滚动 ,以及随后迁移到炎症组织 ,推测其可能与T细胞介导的中枢神经损伤有关。为此 ,我们检测了MS患者sCD6 2E ,以探讨其在MS发病中的作用。1 对象和方法1.1 对象 MS患者 4 5例 ,包括活动期 (AMS) 2 5例 ,稳定期(SMS) 2 0例。男性… 相似文献
198.
Honecker F Kersemaekers AM Molier M Van Weeren PC Stoop H De Krijger RR Wolffenbuttel KP Oosterhuis W Bokemeyer C Looijenga LH 《The Journal of pathology》2004,204(2):167-174
Intercellular contacts, mediated by E-cadherin, are essential for germ cell migration and maturation. Furthermore, it has been suggested that decrease or loss of E-cadherin correlates with tumour progression and invasive behaviour. beta-catenin is involved in a number of different processes, including cell--cell interaction when bound to cadherins, and determination of cell fate in pluripotent cells when activated via the Wnt signal-transduction pathway. To shed more light on the role of these factors in normal fetal germ cell development and the pathogenesis of germ cell tumours (GCTs), the present study investigated the presence and localization of E-cadherin and beta-catenin by immunohistochemistry. E-cadherin was only weakly expressed in or absent from fetal germ cells of the second and third trimesters, and was not expressed in carcinoma in situ/intratubular germ cell neoplasia unclassified (CIS/ITGCNU) and gonadoblastoma, the precursor of an invasive GCT in dysgenetic gonads. In GCTs, it was generally not expressed in seminoma and dysgerminoma, but was found in the vast majority of non-seminoma cells. beta-catenin was found in the cytoplasm of fetal germ cells at all gestational ages and in spermatogenesis in post-pubertal testes. It was also present in CIS/ITGCNU and gonadoblastoma. Whereas seminomas and dysgerminoma were negative, non-seminoma cells were frequently found to express beta-catenin. Expression of both factors therefore reflects the degree of differentiation of these tumours. No differences for either E-cadherin or beta-catenin were observed between samples of tumours resistant or sensitive to chemotherapy, and E-cadherin expression did not correlate with vascular invasion. E-cadherin and beta-catenin therefore play a role in both normal and malignant germ cell development and differentiation that warrants further investigation, but they seem to be of limited value as predictive or prognostic factors in GCTs. 相似文献
199.
200.
流行性乙型脑炎病毒活疫苗株SA14-14-2基因稳定性研究 总被引:1,自引:0,他引:1
目的 通过研究流行性乙型脑炎活疫苗减毒株基因稳定性,从分子水平证实流行性乙型脑炎活疫苗的遗传稳定性。方法分析流行性乙型脑炎活疫苗主种子、工作种子及其相应的疫苗病毒E蛋白基因核苷酸和氨基酸序列,并与其强毒株和基因库中乙脑病毒减毒株(AF15119)比较。结果乙脑活疫苗主种子、工作种子及其相应的疫苗病毒的E蛋白基因核苷酸序列完全相同。这些病毒E蛋白的氨基酸序列与基因库中乙脑病毒弱毒株(AF315119)比较显示第E447位点氨基酸有差异。结论乙脑病毒活疫苗减毒株遗传学特性稳定。 相似文献