全文获取类型
收费全文 | 39517篇 |
免费 | 3160篇 |
国内免费 | 84篇 |
专业分类
耳鼻咽喉 | 297篇 |
儿科学 | 1791篇 |
妇产科学 | 1208篇 |
基础医学 | 5297篇 |
口腔科学 | 410篇 |
临床医学 | 4733篇 |
内科学 | 7370篇 |
皮肤病学 | 690篇 |
神经病学 | 4568篇 |
特种医学 | 746篇 |
外科学 | 3820篇 |
综合类 | 388篇 |
现状与发展 | 1篇 |
一般理论 | 76篇 |
预防医学 | 5371篇 |
眼科学 | 603篇 |
药学 | 2669篇 |
中国医学 | 39篇 |
肿瘤学 | 2684篇 |
出版年
2024年 | 81篇 |
2023年 | 630篇 |
2022年 | 996篇 |
2021年 | 1965篇 |
2020年 | 1175篇 |
2019年 | 1691篇 |
2018年 | 1899篇 |
2017年 | 1289篇 |
2016年 | 1460篇 |
2015年 | 1515篇 |
2014年 | 1996篇 |
2013年 | 2503篇 |
2012年 | 3623篇 |
2011年 | 3501篇 |
2010年 | 1770篇 |
2009年 | 1512篇 |
2008年 | 2330篇 |
2007年 | 2421篇 |
2006年 | 2057篇 |
2005年 | 1882篇 |
2004年 | 1614篇 |
2003年 | 1347篇 |
2002年 | 1199篇 |
2001年 | 193篇 |
2000年 | 146篇 |
1999年 | 218篇 |
1998年 | 248篇 |
1997年 | 151篇 |
1996年 | 129篇 |
1995年 | 126篇 |
1994年 | 126篇 |
1993年 | 105篇 |
1992年 | 83篇 |
1991年 | 72篇 |
1990年 | 63篇 |
1989年 | 52篇 |
1988年 | 54篇 |
1987年 | 52篇 |
1986年 | 56篇 |
1985年 | 46篇 |
1984年 | 48篇 |
1983年 | 36篇 |
1982年 | 35篇 |
1981年 | 32篇 |
1980年 | 35篇 |
1979年 | 32篇 |
1978年 | 24篇 |
1977年 | 15篇 |
1974年 | 14篇 |
1972年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Mode of delivery and risk of developing allergic disease 总被引:3,自引:0,他引:3
McKeever TM Lewis SA Smith C Hubbard R 《The Journal of allergy and clinical immunology》2002,109(5):800-802
The aim of this study was to quantify the relationship between mode of delivery and subsequent incidence of allergic disease. The analysis is based on data derived from a birth cohort of 24,690 children who contributed data to the West Midlands General Practice Research Database. We found no convincing evidence to suggest that babies born by caesarean, forceps, or breech delivery had an increased risk of developing allergic disease. 相似文献
62.
Quantification of Human Immunodeficiency Virus Type 1 RNA Levels in Plasma by Using Small-Volume-Format Branched-DNA Assays 总被引:2,自引:0,他引:2 下载免费PDF全文
Torange Yeghiazarian Yuqi Zhao Stanley E. Read William Kabat Xiaoyi Li Sarah J. Hamren Patrick J. Sheridan Judith C. Wilber David N. Chernoff Ram Yogev 《Journal of clinical microbiology》1998,36(7):2096-2098
We have developed small-volume (50 or 250 μl)-format branched-DNA assays for human immunodeficiency virus type 1 (HIV-1) RNA for use with specimens in which the volume is limited and/or a high viral load is anticipated. These formats exhibited good correlation with the standard 1-ml format; high specificity, reproducibility, and linearity; and no significant difference in the quantification of HIV-1 subtypes. 相似文献
63.
De AK Roach SE De M Minielly RC Laudanski K Miller-Graziano CL Bankey PE 《Journal of immunoassay & immunochemistry》2005,26(1):35-42
Polymorphonuclear leukocytes (PMNs; commonly known as neutrophils) play essential roles in innate immunity and inflammation. Although there are standardized methods for the isolation of human neutrophils, they are time consuming and demand considerable technical expertise, making them unfeasible for many clinical applications. Here, we describe a simple and time-efficient technique for the isolation of human neutrophils, which adapts a readily available commercial cell preparation tube (CPT) currently in use for isolation of peripheral blood mononuclear cells (PBMC) and plasma and is now adapted to also yield neutrophils. The total time required for neutrophil isolation was less than 1 hr. Neutrophils isolated by this method were highly purified (> or =97%) as assessed by surface expression of the neutrophil specific marker, CD66b. Neutrophils isolated by this method were functional as demonstrated by their ability to secrete interleukin-1 receptor antagonist (IL-1RA). Neutrophils isolated using this new technique secreted significant amounts of soluble IL-1RA (929.3+/-197 pg/10(6)cells/mL) in response to lipopolysaccharide (LPS). Use of this adapted CPT method allows simultaneous isolation of functional human neutrophils as well as PBMC and plasma. Adoption of this new method will allow the conduct of different neutrophil assays at any clinical site without requiring trained laboratory personnel or a large staff time commitment. 相似文献
64.
65.
66.
67.
Upregulation of TGF-beta, FOXP3, and CD4+CD25+ regulatory T cells correlates with more rapid parasite growth in human malaria infection 总被引:8,自引:0,他引:8
Walther M Tongren JE Andrews L Korbel D King E Fletcher H Andersen RF Bejon P Thompson F Dunachie SJ Edele F de Souza JB Sinden RE Gilbert SC Riley EM Hill AV 《Immunity》2005,23(3):287-296
Understanding the regulation of immune responses is central for control of autoimmune and infectious disease. In murine models of autoimmunity and chronic inflammatory disease, potent regulatory T lymphocytes have recently been characterized. Despite an explosion of interest in these cells, their relevance to human disease has been uncertain. In a longitudinal study of malaria sporozoite infection via the natural route, we provide evidence that regulatory T cells have modifying effects on blood-stage infection in vivo in humans. Cells with the characteristics of regulatory T cells are rapidly induced following blood-stage infection and are associated with a burst of TGF-beta production, decreased proinflammatory cytokine production, and decreased antigen-specific immune responses. Both the production of TGF-beta and the presence of CD4+CD25+FOXP3+ regulatory T cells are associated with higher rates of parasite growth in vivo. P. falciparum-mediated induction of regulatory T cells may represent a parasite-specific virulence factor. 相似文献
68.
Turrisi R Hillhouse J Heavin S Robinson J Adams M Berry J 《Journal of behavioral medicine》2004,27(4):393-412
The research evaluated an intervention strategy designed to prevent skin cancer in young adolescents. The intervention used parents as change agents to effectively communicate the risks of skin cancer and encourage their children to avoid high-risk sun-related behaviors while increasing positive sun-safe behaviors. Three hundred and forty parents in two regions of the United States were educated about the dangers of risky sun behaviors and how to convey information about skin cancer prevention to their children. Parents were then encouraged to talk with their children about these issues over a 1-month period prior to the onset of summer. Following this time period, children whose parents received and implemented the intervention materials were compared with a control sample of 129 children. These two groups were matched on age, gender, and school on number of sunburns and sunburn severity, attitudes and beliefs, and sunbathing behavior. Children in the treatment condition differed significantly from controls in the predicted directions on all outcome variables. The findings are discussed in terms of reducing skin cancer risk behaviors of children via parent-based intervention approaches. 相似文献
69.
Analysis of the Virus Population Present in Equine Faeces Indicates the Presence of Hundreds of Uncharacterized Virus Genomes 总被引:7,自引:0,他引:7
Virus DNA was isolated from horse faeces and cloned in a sequence-independent fashion. 268 clones were sequenced and 178140 nucleotides of sequence obtained. Statistical analysis suggests the library contains 17560 distinct clones derived from up to 233 different virus genomes. TBLASTX analysis showed that 32% of the clones had significant identity to GenBank entries. Of these 63% were viral; 20% bacterial; 7% archaeal; 6% eukarya; and 5% were related to mobile genetic elements. Fifty-two percent of the virus identities were with Siphoviridae; 26% unclassified phages; 17% Myoviridae; 4% Podoviridae; and one clone (2%) was a vertebrate Orthopoxvirus. Genes coding for predicted virus structural proteins, proteases, glycosidases and nucleic acid-binding proteins were common. 相似文献
70.
Casey Graham; Plummer Sarah; Hoeltge Gerald; Scanlon David; Fasching Clare; Stanbridge Eric J. 《Human molecular genetics》1993,2(11):1921-1927
Rearrangements or deletions of chromosome 17 are the most frequentlyobserved genetic changes identified in breast tumors. Molecularanalyses suggest that in addition to the p53 gene on 17p13.1there may be at least three other tumor suppressor genes onchromosome 17 involved in breast cancer. Regions of loss ofheterozygosity (LOH) identified on 17p13.3 and 17q12-qter occurfrequently in breast tumors, and the BRCA-1 gene has been mappedto 17q21 by genetic linkage analysis. Here we provide biologicalevidence for the presence of a growth suppressor gene(s) onchromosome 17 that results In the In vitro growth suppressionof the p53 wild-type MCF 7 breast cancer cell line. We haveIntroduced a normal chromosome 17 into MCF 7 cells by microcellmediatedchromosome transfer (MMCT), and demonstrate that cells growtharrest before 10 to 12 population doublings. In contrast, theintroduction of a normal chromosome 13 had no effect upon growthof these cells either In vitro or In vivo. These data providedirect functional evidence for the presence of a growth suppressorgene(s) on chromosome 17, which is not p53, and which may representone of several gene(s) that play a critical role in the developmentof breast cancer. 相似文献