全文获取类型
收费全文 | 175133篇 |
免费 | 16302篇 |
国内免费 | 9382篇 |
专业分类
耳鼻咽喉 | 1554篇 |
儿科学 | 2755篇 |
妇产科学 | 3520篇 |
基础医学 | 17585篇 |
口腔科学 | 3575篇 |
临床医学 | 22504篇 |
内科学 | 25951篇 |
皮肤病学 | 2117篇 |
神经病学 | 8155篇 |
特种医学 | 5607篇 |
外国民族医学 | 59篇 |
外科学 | 16343篇 |
综合类 | 29550篇 |
现状与发展 | 36篇 |
一般理论 | 23篇 |
预防医学 | 14152篇 |
眼科学 | 4570篇 |
药学 | 18923篇 |
169篇 | |
中国医学 | 10241篇 |
肿瘤学 | 13428篇 |
出版年
2024年 | 499篇 |
2023年 | 2313篇 |
2022年 | 5410篇 |
2021年 | 7299篇 |
2020年 | 5680篇 |
2019年 | 4846篇 |
2018年 | 5171篇 |
2017年 | 5128篇 |
2016年 | 4504篇 |
2015年 | 7162篇 |
2014年 | 9260篇 |
2013年 | 9721篇 |
2012年 | 14103篇 |
2011年 | 15019篇 |
2010年 | 10842篇 |
2009年 | 9034篇 |
2008年 | 10859篇 |
2007年 | 10759篇 |
2006年 | 10187篇 |
2005年 | 9160篇 |
2004年 | 6614篇 |
2003年 | 6006篇 |
2002年 | 5060篇 |
2001年 | 4139篇 |
2000年 | 3774篇 |
1999年 | 3281篇 |
1998年 | 1674篇 |
1997年 | 1568篇 |
1996年 | 1248篇 |
1995年 | 1201篇 |
1994年 | 1102篇 |
1993年 | 616篇 |
1992年 | 1059篇 |
1991年 | 969篇 |
1990年 | 808篇 |
1989年 | 699篇 |
1988年 | 632篇 |
1987年 | 574篇 |
1986年 | 458篇 |
1985年 | 361篇 |
1984年 | 241篇 |
1983年 | 220篇 |
1982年 | 124篇 |
1981年 | 123篇 |
1980年 | 101篇 |
1979年 | 165篇 |
1978年 | 136篇 |
1974年 | 108篇 |
1973年 | 101篇 |
1972年 | 110篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
991.
J A Lowe N R Ling J A Forrester A J Cumber W C Ross 《Journal of immunological methods》1985,76(1):93-104
Conjugates of ricin A-chain with monoclonal anti-light chain antibodies specifically killed cells hearing kappa or lambda immunoglobulin (Ig) light chains. Exposure of cells from B-lymphoblastoid cell lines (B-LCL) to conjugate for less than 30 h had only a slight effect on cell growth, but on 48 h exposure a marked killing effect was achieved. After recovery of growth, cells were re-exposed to conjugate for 9-14 days. Treatment of cells from the EB4 line (sIgG lambda) in this way yielded 4 variants which showed a marked reduction in levels of surface Ig lambda and secreted Ig lambda with slight, or no, reduction in MHC class II expression and similar growth rates to the parent line. Variant lines retained their phenotype over long periods of culture. 相似文献
992.
《中国医院知识仓库》在我院局域网上的使用 总被引:9,自引:1,他引:9
通过介绍《中国医院知识仓库(CHKD)》在我院局域网上的安装和使用情况.阐明CHKD在医院中的作用。 相似文献
993.
Calorie restriction (CR) extends life span in a wide variety of species. Previously, we showed that calorie restriction increases the replicative life span in yeast by activating Sir2, a highly conserved NAD-dependent deacetylase. Here we test whether CR activates Sir2 by increasing the NAD/NADH ratio or by regulating the level of nicotinamide, a known inhibitor of Sir2. We show that CR decreases NADH levels, and that NADH is a competitive inhibitor of Sir2. A genetic intervention that specifically decreases NADH levels increases life span, validating the model that NADH regulates yeast longevity in response to CR. 相似文献
994.
NIH 3T3细胞转化前后细胞骨架及细胞表面纤维粘连蛋白的免疫荧光观察 总被引:1,自引:0,他引:1
本实验用抗纤维粘连蛋白(FN)亲和层析纯抗体和抗管蛋白抗体及鬼笔环肽,以免疫荧光组织化学方法,对NIH3T3细胞转染人肺腺癌细胞系AGZY基因组DNA前后细胞表面FN及细胞内骨架系统进行染色观察。结果表明,细胞在发生转化后,微丝及微管均表现出明显受损,细胞骨架结构不清,呈现为弥散样荧光;细胞表面FN大量减少,仅及正常NIH3T3细胞的1/9,其分布也由细丝形成的网状,变成斑点或斑块状。这一结果进一步证实,细胞恶变是涉及到细胞骨架系统及膜表面糖蛋白变化的复杂过程,并预示这些变化可能就是导致细胞形态发生变化、细胞失去正常生长调控的原因之一。 相似文献
995.
996.
An analysis of myeloma plasma cell phenotype using antibodies defined at the IIIrd International Workshop on Human Leucocyte Differentiation Antigens. 总被引:2,自引:2,他引:2
下载免费PDF全文
![点击此处可从《Clinical and experimental immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
N Jackson N R Ling J Ball E Bromidge P D Nathan I M Franklin 《Clinical and experimental immunology》1988,72(3):351-356
Fresh bone marrow from 43 cases of myeloma and three cases of plasma cell leukaemia has been phenotyped both by indirect immune-rosetting and, on fixed cytospin preparations, by indirect immunofluorescence. Both clustered and unclustered B cell associated antibodies from the IIIrd International Workshop on Human Leucocyte Differentiation Antigens were used. The results confirm the lack of many pan-B antigens on the surface of myeloma plasma cells, i.e. CD19-23, 37, 39, w40. Strong surface reactivity is seen with CD38 antibodies and with one CD24 antibody (HB8). Weak reactions are sometimes obtained with CD9, 10 and 45R. On cytospin preparations CD37, 39 and w40 are sometimes weakly positive, and anti-rough endoplasmic reticulum antibodies are always strongly positive. Specific and surface-reacting antiplasma cell antibodies are still lacking. 相似文献
997.
The change of the specific activity of S-adenosylmethionine: tRNA methyltransferase in cultures of human diploid fibroblasts at different passages has been measured and compared with that in the same type of cells derived from donors of different ages. Whereas the specific activity of tRNA methylase in the in vitro aged cells was found to decline gradually with increasing passage number of the culture, a different activity--age relationship was observed for this enzyme in cells derived from donors of different ages. The activity of tRNA methylase is high in the fetal cells and drops drastically in the "newborn" cells. After a further 10% decline, the activity of this enzyme reaches a steady low level in the postnatal cells from donors ranging in age from 3 months to 94 years. These findings cast doubt on the validity of the assumption that the results obtained from in vitro aging experiments reflect the biochemistry of aging in vivo. The "fetal" enzyme can methylate the "aged" tRNA but the "aged" enzyme cannot methylate the "fetal" tRNA. The fetal cells contain enzyme activities specific for the formation of m1A, m5C and m1G. These activities are low or deficient in "aged" cells. Control experiments showed that all of these results are due neither to the presence of inhibitor or stimulator in the extract nor to effects related to the population density, sex or growth rate of the culture. 相似文献
998.
The interaction of normal lymphocytes and cells from lymphoid cell lines: II. Variations relating to cell line source and lymphocyte donor
下载免费PDF全文
![点击此处可从《Immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Irradiated LCL cells from several sources activated the blood lymphocytes of a panel of donors. Individual differences were present but were small. Stimulated blood lymphocytes were more potent activators (after X-irradiation) than small lymphocytes in a one-way mixed lymphocyte reaction, indicating that the state of metabolic activity of the `stimulating' lymphocyte affects the level of activation achieved. However, LCL cells incubated for several days after irradiation had not lost stimulatory capacity. Lymphocytes of pigs, rabbits, rats and mice were much less responsive than human lymphocytes. The response of animal lymphocytes generally varied with the species of origin of the serum used in the cultures. 相似文献
999.
无菌分离小鼠腹腔巨噬细胞,制备单细胞悬液,加入不同终浓度的淫羊藿甙孵育4 h后,加入细菌脂多糖LPS(终浓度20 mg/L)48 h后以MTT法检测其增殖;加药孵育4 h后,分别加入直径1μm和2μm的微球(终浓度1×1010/L),5 h后利用流式细胞术(FCM)检测吞噬情况;加入LPS(终浓度20 mg/L)24 h后Griess试剂盒检测巨噬细胞NO的量。结果显示ICA在终浓度1.5、3.0μmol/L时能明显抑制LPS刺激的巨噬细胞增殖(P<0.01)和NO的产生,并促进其吞噬微球的功能。提示ICA可能抑制LPS信号转导从而抑制巨噬细胞增殖,并且通过抑制其活化,下调iNOS有关的炎症因子,使NO减少;对于未活化的巨噬细胞,ICA可能通过上调其吞噬功能,增强固有免疫系统来抵御病原体侵入。 相似文献
1000.
基于通用中间件接口服务器的远程医疗信息系统 总被引:1,自引:0,他引:1
在远程医疗信息系统共享平台的设计中,提出一种构建通用中间件接口服务器实现多家医院信息系统HIS与PACS的无缝连接方案。着重介绍了DICOM中间件、HL7消息中间件、生态识别和PKI技术在系统集成中的应用。 相似文献