全文获取类型
收费全文 | 576篇 |
免费 | 91篇 |
国内免费 | 61篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 23篇 |
妇产科学 | 4篇 |
基础医学 | 72篇 |
口腔科学 | 7篇 |
临床医学 | 103篇 |
内科学 | 119篇 |
皮肤病学 | 10篇 |
神经病学 | 18篇 |
特种医学 | 87篇 |
外科学 | 119篇 |
综合类 | 22篇 |
预防医学 | 14篇 |
眼科学 | 6篇 |
药学 | 52篇 |
中国医学 | 1篇 |
肿瘤学 | 70篇 |
出版年
2021年 | 10篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2015年 | 12篇 |
2014年 | 14篇 |
2013年 | 13篇 |
2012年 | 11篇 |
2011年 | 13篇 |
2010年 | 17篇 |
2009年 | 22篇 |
2008年 | 12篇 |
2007年 | 50篇 |
2006年 | 24篇 |
2005年 | 26篇 |
2004年 | 10篇 |
2003年 | 12篇 |
2002年 | 27篇 |
2001年 | 14篇 |
2000年 | 11篇 |
1999年 | 18篇 |
1998年 | 33篇 |
1997年 | 38篇 |
1996年 | 28篇 |
1995年 | 25篇 |
1994年 | 15篇 |
1993年 | 25篇 |
1992年 | 7篇 |
1991年 | 8篇 |
1990年 | 11篇 |
1989年 | 22篇 |
1988年 | 10篇 |
1987年 | 17篇 |
1986年 | 10篇 |
1985年 | 9篇 |
1984年 | 14篇 |
1983年 | 6篇 |
1981年 | 6篇 |
1980年 | 12篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1976年 | 5篇 |
1975年 | 8篇 |
1973年 | 9篇 |
1972年 | 5篇 |
1971年 | 5篇 |
1969年 | 9篇 |
1968年 | 8篇 |
1967年 | 5篇 |
1966年 | 4篇 |
排序方式: 共有728条查询结果,搜索用时 15 毫秒
81.
Murine hematopoietic stem and progenitor cells: I. Enrichment and biologic characterization 总被引:2,自引:5,他引:2
Murine bone marrow cells were fractionated by fluorescence-activated cell sorting into Rh123lo Lin- c-kit+ Ly6A+, Rh123hi Lin-c-kit+ Ly6A+, and Lin- c-kit+ Ly6A- populations within which most, if not all, of the hematopoietic activities of the marrow resided. The Rh123lo Lin- c- kit+Ly6A+ cells, which consist exclusively of small- or medium-sized lymphocyte-like cells, are highly enriched for long-term hematopoietic in vivo repopulating cells. The enrichment factor for these cells from the marrow was estimated as 2,000-fold. The Rh123hi Lin- c-kit+ Ly6A+ cells, although also highly enriched for day-12 spleen colony-forming units, were relatively depleted of long-term in vivo repopulation capacity. Most, if not all Lin- c-kit+ Ly6A- cells were Rb123hi. In contrast to both Rh123lo and Rh123hi Lin- c-kit+ Ly6A+ stem cell populations, the Lin- c-kit+ Ly6A- cells can be stimulated to proliferate in vitro in the presence of single cytokines, which is a characteristic of committed progenitor cells. No marked synergistic interactions between individual cytokines were observed with this cell population. Both Rh123hi Lin- c-kit+ Ly6A+ mature stem cell and Lin- c- kit+ Ly6A- progenitor cell populations displayed in vivo repopulation kinetics resembling those of the putative short-term hematopoietic repopulating cells. 相似文献
82.
83.
To determine the relationship between equilibrium binding of thrombin to sites on the platelet surface and the cleavage of membrane glycoprotein V (GPV) by thrombin, we examined the effect of active site- modified thrombin (1-chloro-3-tosylamido-7-amino-L-2-heptanone thrombin toslysCH2-thrombin) on the binding of native thrombin to platelets and on the hydrolysis of GPV by native thrombin. ToslysCH2-thrombin inhibited binding of native thrombin to high affinity sites on the platelet surface. In contrast, hydrolysis of GPV by native thrombin, even at threshold thrombin concentrations, was not inhibited by pretreatment with toslysCH2-thrombin at concentrations up to 210 nmol/L. ToslysCH2-thrombin also had no appreciable effect on platelet aggregation or release of 14C-serotonin induced by native thrombin. Because toslysCH2-thrombin does not inhibit platelet release, aggregation, or GPV hydrolysis by native thrombin but does inhibit high affinity surface binding by native thrombin, these results indicate that thrombin binding and hydrolysis of GPV are separate and unrelated events. 相似文献
84.
85.
86.
87.
88.
Zollikofer CL; Cragg AH; Einzig S; Castaneda-Zuniga WR; Castaneda F; Rysavy JA; Bruhlmann WF; Shebuski RJ; Amplatz K 《Radiology》1983,149(3):681-685
To prevent platelet aggregation following percutaneous transluminal angioplasty (PTA), cyclooxygenase inhibitors such as acetylsalicylic acid (ASA) and indomethacin are recommended. However, ASA blocks both the proaggregating effects of thromboxane (TXA2) and the antiaggregating and vasodilating effects of prostacyclin (PGI2). The authors measured the contractile response of dilated canine carotid arteries in situ and in vitro using an isometric force transducer. Following PTA, contraction of the arterial wall was significantly reduced (p less than 0.01). By blocking cyclooxygenase with indomethacin (3 micrograms/ml), contraction was greatly improved (p less than 0.001). These results suggest that PTA may result in marked release of prostacyclin by the damaged arterial wall, which could account for the decreased responsiveness of the artery to exogenous norepinephrine. 相似文献
89.
90.
The CTLA-4 gene region of chromosome 2q33 is linked to, and associated with, type 1 diabetes. Belgian Diabetes Registry 总被引:8,自引:1,他引:8
Nistico L; Buzzetti R; Pritchard LE; Van der Auwera B; Giovannini C; Bosi E; Larrad MT; Rios MS; Chow CC; Cockram CS; Jacobs K; Mijovic C; Bain SC; Barnett AH; Vandewalle CL; Schuit F; Gorus FK; Tosi R; Pozzilli P; Todd JA 《Human molecular genetics》1996,5(7):1075-1080
Susceptibility to autoimmune insulin-dependent (type 1) diabetes mellitus
is determined by a combination of environmental and genetic factors, which
include variation in MHC genes on chromosome 6p21 (IDDM1) and the insulin
gene on chromosome 11p15 (IDDM2). However, linkage to IDDM1 and IDDM2
cannot explain the clustering of type 1 diabetes in families, and a role
for other genes is inferred. In the present report we describe linkage and
association of type 1 diabetes to the CTLA-4 gene (cytotoxic T lymphocyte
associated-4) on chromosome 2q33 (designated IDDM12). CTLA-4 is a strong
candidate gene for T cell- mediated autoimmune disease because it encodes a
T cell receptor that mediates T cell apoptosis and is a vital negative
regulator of T cell activation. In addition, we provide supporting evidence
that CTLA-4 is associated with susceptibility to Graves' disease, another
organ- specific autoimmune disease.
相似文献