全文获取类型
收费全文 | 15067篇 |
免费 | 1030篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 92篇 |
儿科学 | 502篇 |
妇产科学 | 390篇 |
基础医学 | 1868篇 |
口腔科学 | 100篇 |
临床医学 | 2210篇 |
内科学 | 2821篇 |
皮肤病学 | 217篇 |
神经病学 | 1356篇 |
特种医学 | 391篇 |
外国民族医学 | 1篇 |
外科学 | 1372篇 |
综合类 | 204篇 |
一般理论 | 16篇 |
预防医学 | 2049篇 |
眼科学 | 180篇 |
药学 | 1011篇 |
中国医学 | 16篇 |
肿瘤学 | 1323篇 |
出版年
2024年 | 15篇 |
2023年 | 100篇 |
2022年 | 167篇 |
2021年 | 344篇 |
2020年 | 228篇 |
2019年 | 390篇 |
2018年 | 421篇 |
2017年 | 319篇 |
2016年 | 339篇 |
2015年 | 403篇 |
2014年 | 522篇 |
2013年 | 792篇 |
2012年 | 1195篇 |
2011年 | 1174篇 |
2010年 | 635篇 |
2009年 | 606篇 |
2008年 | 945篇 |
2007年 | 1104篇 |
2006年 | 1030篇 |
2005年 | 1026篇 |
2004年 | 903篇 |
2003年 | 880篇 |
2002年 | 751篇 |
2001年 | 103篇 |
2000年 | 63篇 |
1999年 | 119篇 |
1998年 | 171篇 |
1997年 | 126篇 |
1996年 | 116篇 |
1995年 | 122篇 |
1994年 | 108篇 |
1993年 | 100篇 |
1992年 | 59篇 |
1991年 | 43篇 |
1990年 | 43篇 |
1989年 | 46篇 |
1988年 | 50篇 |
1987年 | 42篇 |
1986年 | 36篇 |
1985年 | 36篇 |
1984年 | 47篇 |
1983年 | 38篇 |
1982年 | 50篇 |
1981年 | 49篇 |
1980年 | 39篇 |
1979年 | 27篇 |
1978年 | 25篇 |
1977年 | 18篇 |
1976年 | 24篇 |
1975年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
Background
The efficacy of academic detailing in changing physicians' knowledge and practice has been the subject of many primary research publications and systematic reviews. However, there is little written about the features of academic detailing that physicians find valuable or that affect their use of it. The goal of our project was to explore family physicians' (FPs) perceptions of academic detailing and the factors that affect their use of it. 相似文献63.
Manfred Kopf Suzanne Herren Michael V. Wiles Mark B. Pepys Marie H. Kosco-Vilbois 《The Journal of experimental medicine》1998,188(10):1895-1906
Mice rendered deficient for interleukin (IL) 6 by gene targeting were evaluated for their response to T cell–dependent antigens. Antigen-specific immunoglobulin (Ig)M levels were unaffected whereas all IgG isotypes showed varying degrees of alteration. Germinal center reactions occurred but remained physically smaller in comparison to those in the wild-type mice. This concurred with the observations that molecules involved in initial signaling events leading to germinal center formation were not altered (e.g., B7.2, CD40 and tumor necrosis factor R1). T cell priming was not impaired nor was a gross imbalance of T helper cell (Th) 1 versus Th2 cytokines observed. However, B7.1 molecules, absent from wild-type counterparts, were detected on germinal center B cells isolated from the deficient mice suggesting a modification of costimulatory signaling. A second alteration involved impaired de novo synthesis of C3 both in serum and germinal center cells from IL-6–deficient mice. Indeed, C3 provided an essential stimulatory signal for wild-type germinal center cells as both monoclonal antibodies that interrupted C3-CD21 interactions and sheep anti–mouse C3 antibodies caused a significant decrease in antigen-specific antibody production. In addition, germinal center cells isolated from C3–deficient mice produced a similar defect in isotype production. Low density cells with dendritic morphology were the local source of IL-6 and not the germinal center lymphocytes. Adding IL-6 in vitro to IL-6–deficient germinal center cells stimulated cell cycle progression and increased levels of antibody production. These findings reveal that the germinal center produces and uses molecules of the innate immune system, evolutionarily pirating them in order to optimally generate high affinity antibody responses. 相似文献
64.
65.
66.
67.
68.
The Proceedings of the Round Table Conference will be published as volume 19, in the series Update in Intensive Care and Emergency Medicine (Springer Verlag) in January, 1995. 相似文献
69.
70.
A cDNA for the estradiol-regulated 24K protein: Control of mRNA levels in MCF-7 cells 总被引:1,自引:0,他引:1
Ines Moretti-Rojas Suzanne A. W. Fuqua Robert A. Montgomery III William L. McGuire 《Breast cancer research and treatment》1988,11(2):155-163
We have previously demonstrated an estradiol-regulated 24 kDa (24K) protein in human breast cancer tissue culture cells and human tumor biopsies. The presence of 24K correlates well with the presence of steroid hormone receptors. In order to further study the hormonal regulation of the 24K protein and gene, we have isolated cDNA clones corresponding to the 24K mRNA.Poly(A)+ RNA isolated from the MCF-7 human breast cancer cell line was translated in a cell-free translation system containing [35S]-methionine. The translation products were immunoprecipitated with a 24K monoclonal antibody, and thein vitro synthesis of 24K protein was confirmed by sodium dodecylsulfate (SDS) polyacrylamide gel electrophoresis. The same poly(A)+ RNA was used to construct an oligo(dT)-primed cDNA library in thegt11 expression vector system. The library was screened with a highly specific polyclonal antibody raised against 24K protein purified by immunoaffinity chromatography. Four recombinant clones reacting with the antibody by virtue of antigen expression were isolated and three were used in hybridization-selected translation. Three clones were able to hybridize specifically to a messenger RNA (mRNA) that yielded a Mr 24,000 protein when translatedin vitro and analyzed by SDS/polyacrylamide gel electrophoresis. This protein was also immunoprecipitable by the 24K monoclonal antibody. MCF-7 mRNA size fractionated by formaldehyde-agarose gel electrophoresis was transferred to nitrocellulose paper and hybridized to a nick-translated 24K cDNA clone. A single band of hybridization corresponding to a mRNA size of approximately 0.9–1.0 kilobase (kb) was observed. Using this same technique, 24K cDNA was hybridized to mRNA extracted from MCF-7 cells that had been treated for varying periods with either estradiol, nafoxidine, or tamoxifen. The 24K mRNA was elevated by the addition of estradiol, and clearly diminished by nafoxidine and tamoxifen.These results demonstrate that we have isolated cDNA clones for the study of the hormonal regulation of the 24K gene in breast cancer cells, and have shown that the mRNA is regulated by estradiol. 相似文献