全文获取类型
收费全文 | 118862篇 |
免费 | 6913篇 |
国内免费 | 1581篇 |
专业分类
耳鼻咽喉 | 1575篇 |
儿科学 | 2970篇 |
妇产科学 | 4107篇 |
基础医学 | 18296篇 |
口腔科学 | 3608篇 |
临床医学 | 9273篇 |
内科学 | 21609篇 |
皮肤病学 | 2436篇 |
神经病学 | 8018篇 |
特种医学 | 4019篇 |
外国民族医学 | 3篇 |
外科学 | 16743篇 |
综合类 | 5213篇 |
一般理论 | 34篇 |
预防医学 | 8687篇 |
眼科学 | 2818篇 |
药学 | 10198篇 |
中国医学 | 818篇 |
肿瘤学 | 6931篇 |
出版年
2021年 | 982篇 |
2019年 | 1047篇 |
2018年 | 1612篇 |
2017年 | 1168篇 |
2016年 | 1196篇 |
2015年 | 1445篇 |
2014年 | 1884篇 |
2013年 | 2441篇 |
2012年 | 3542篇 |
2011年 | 3794篇 |
2010年 | 2285篇 |
2009年 | 2047篇 |
2008年 | 3379篇 |
2007年 | 3614篇 |
2006年 | 3596篇 |
2005年 | 3163篇 |
2004年 | 2975篇 |
2003年 | 2770篇 |
2002年 | 2626篇 |
2001年 | 6730篇 |
2000年 | 6921篇 |
1999年 | 5695篇 |
1998年 | 1829篇 |
1997年 | 1377篇 |
1996年 | 935篇 |
1995年 | 862篇 |
1992年 | 3728篇 |
1991年 | 3806篇 |
1990年 | 3549篇 |
1989年 | 3552篇 |
1988年 | 3428篇 |
1987年 | 3277篇 |
1986年 | 3090篇 |
1985年 | 2967篇 |
1984年 | 2048篇 |
1983年 | 1792篇 |
1982年 | 985篇 |
1979年 | 1909篇 |
1978年 | 1184篇 |
1977年 | 986篇 |
1976年 | 918篇 |
1975年 | 1191篇 |
1974年 | 1358篇 |
1973年 | 1413篇 |
1972年 | 1357篇 |
1971年 | 1247篇 |
1970年 | 1137篇 |
1969年 | 1121篇 |
1968年 | 1024篇 |
1967年 | 897篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
961.
Relation of impaired lymphocyte proliferative function to other major human immunodeficiency virus type 1-induced immunological changes. 下载免费PDF全文
H Z Bass J L Fahey P Nishanian R Detels W Cumberland M Kemeny S Plaeger 《Clinical and Vaccine Immunology : CVI》1997,4(1):64-69
Human immunodeficiency virus (HIV) type 1 (HIV-1) induces impairment of immune function reflected in reduced lymphocyte proliferative responses. Many other immune changes are induced by HIV-1, but their relationship to lymphocyte functional defects is not known. The present study was designed to correlate functional defects with other HIV disease parameters. Cryopreserved samples from 118 HIV-1-positive subjects and 40 seronegative individuals were examined. The main findings were that impaired proliferative responses to mitogens correlated with (i) decreased cell surface expression of the interleukin-2 receptor (CD25), (ii) increased expression of HLA-DR antigens on CD4 cells, (iii) reduced CD4 and increased CD8 cell numbers, and (iv) increased levels of serum immune complex dissociated p24 antigen. However, impaired function was not associated with increased serum neopterin, beta2-microglobulin, or soluble interleukin-2 receptor or with CD38 antigen expression on lymphocytes. In summary, proliferative functional impairment correlated with some, but not all, immunological changes associated with HIV-1 infection. Most of the phenotypic markers that correlated with altered function are cell surface molecules with significant roles in lymphocyte proliferation and were associated primarily with CD4 cells, compatible with the view that dysregulation of CD4 cells is responsible for impaired function. 相似文献
962.
M. Rogol I. Sechter H. Falk Y. Shtark S. Alfi Z. Greenberg R. Mizrachi 《European journal of clinical microbiology & infectious diseases》1983,2(6):588-590
A report is given on an outbreak of enteritis which occurred in July 1982 in a kibbutz near Jerusalem. About 150 of the 512 inhabitants were affected.Campylobacter jejuni was isolated from ten out of 42 stool samples examined toward the end of the outbreak. No other enteric pathogen was found. Strong circumstantial evidence indicated an association between the outbreak and the use of water from an unprotected reservoir, but no bacteriological confirmation was obtained. 相似文献
963.
Preferential production of rabbit reaginic antibodies 总被引:4,自引:0,他引:4
964.
965.
966.
Birds on a commercial turkey Farm were treated with fenbendazole on two separate occasions. For each treatment, fenbendazole was administered in the feed for 3 days at 30 mg/kg. Mean Ascaridia dissimilis total counts in randomly selected birds were 14.4 and 33.0 prior to the first and second treatments, respectively, whilst post-treatment counts averaged only 0.1 and 0.3, respectively. Anthelmintic effectiveness as demonstrated by both treatments was >99.0%. No untoward effects were noted with either fenbendazole treatment. After fenbendazole withdrawal, routine treatments with piperazine dihydrochloride were commenced with no apparent anthelmintic effectiveness. Mean total nematode burdens rose to 153.9 with a high individual count of 451. The potential for severe ascaridiasis when effective anthelmintic intervention is precluded was demonstrated. 相似文献
967.
Recent studies from this laboratory have found, contrary to a long-held belief, that synthetic peptides of a protein, as small as six residues, when immunized in their free form (i.e., without coupling to any carrier), elicit the formation of antibodies with submolecular binding specificities to preselected protein regions. These peptides could represent either the antigenic sites of the protein or surface regions that are not immunogenic when the intact protein is the antigen. In either case, the antibodies bind specifically to the intact protein, exclusively at the region used in immunization. Monoclonal antibodies with preselected specificities can also be produced by hybridoma technology from the spleens of the immunized animals. Furthermore, free synthetic peptides have been employed to generate T-cell lines and T-cell clones with specificities to preselected immunogenic locations and also to induce tolerance to such preselected locations. These fascinating breakthroughs indicate that free synthetic peptides may be used in the future as powerful tools in basic investigations and in therapeutic and diagnostic applications. 相似文献
968.
969.
A. K. Chepurov Z. M. Belomestnaya I. A. Donetskii G. V. Tsidvintseva 《Bulletin of experimental biology and medicine》1980,89(3):289-292
The thromboresistant properties of hydrophilic gels based on copolymers of nitrogen-containing heterocyclic vinyl compounds with vinyl monomers were investigated. The hydrophilic gels were shown to prevent adsorption of fibrinogen, activation of procoagulants, and adhesion of platelets. Hydrogen surfaces possess selective affinity for plasma albumin. The authors consider that the thromboresistant effect of hydrophilic gels is due to the competitive action of plasma albumin. Modification of hydrophilic gels increases their thromboresistant properties.Laboratory of Thromboresistant Materials, Institute of Transplantation of Organs and Tissues, Ministry of Health of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. M. Chernukh.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 89, No. 3, pp. 296–298, March, 1980. 相似文献
970.
Genetic control of the immune response to haemoglobin. II. Studies using purified alpha-chain and beta-chain as immunogens 总被引:1,自引:0,他引:1
Mice of independent haplotypes and several recombinant inbred strains were immunized with highly purified preparations of either the alpha-chain or beta-chain subunit of human adult haemoglobin. Cells from the sensitized lymph nodes were challenged in vitro with the appropriate subunit (or in some cases both chains) and cell proliferation assessed by 3H-thymidine incorporation. Mice of the H-2b and H-2d haplotypes were high responders to alpha-chain while mice of the H-2f, H-2j, H-2k, H-2r, H-2s, H-2u, and H-2v haplotype were low responders. the low responsivenesss of B10.A(4R) and B 10.MBR and high responsiveness of B10 indicated that the Ir gene(s) determining responsiveness to the alpha-chain subunit resides in the I-A subregion of the mouse major histocompatibility complex. Mice of the H-2d, H-2f, and H-2s haplotypes were high responders and H-2b, H-2j, H-2a, and H-2u haplotype mice were low responders to beta-chain. H-2k, H-2p, H-2r, and H-2v haplotype mice were intermediate responders to beta-chain. The low responsiveness of B10.S(8R) and B10.TL and the high responsivenes of B10.S(9R) mapped the Ir gene(s) to beta-chain to the I-A subregion. Data collected from challenging high responder cells with both subunit indicated that alpha-chain and beta-chain do not crossreact. These results are discussed in reference to earlier observations suggesting that the low responsiveness of some strains of mice to priming and challenging using the intact haemoglobin molecule might be due to a negative regulatory influence mediated by one of the subunits. In the absence of this influence these mice would respond normally. 相似文献