全文获取类型
收费全文 | 1144篇 |
免费 | 88篇 |
国内免费 | 36篇 |
专业分类
耳鼻咽喉 | 14篇 |
儿科学 | 68篇 |
妇产科学 | 14篇 |
基础医学 | 112篇 |
口腔科学 | 24篇 |
临床医学 | 138篇 |
内科学 | 250篇 |
皮肤病学 | 183篇 |
神经病学 | 50篇 |
特种医学 | 170篇 |
外科学 | 72篇 |
综合类 | 16篇 |
一般理论 | 1篇 |
预防医学 | 44篇 |
眼科学 | 11篇 |
药学 | 60篇 |
肿瘤学 | 41篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 8篇 |
2020年 | 20篇 |
2019年 | 18篇 |
2018年 | 26篇 |
2017年 | 20篇 |
2016年 | 22篇 |
2015年 | 23篇 |
2014年 | 32篇 |
2013年 | 43篇 |
2012年 | 42篇 |
2011年 | 35篇 |
2010年 | 61篇 |
2009年 | 57篇 |
2008年 | 39篇 |
2007年 | 56篇 |
2006年 | 35篇 |
2005年 | 40篇 |
2004年 | 24篇 |
2003年 | 26篇 |
2002年 | 32篇 |
2001年 | 25篇 |
2000年 | 28篇 |
1999年 | 19篇 |
1998年 | 53篇 |
1997年 | 49篇 |
1996年 | 47篇 |
1995年 | 44篇 |
1994年 | 44篇 |
1993年 | 30篇 |
1992年 | 7篇 |
1991年 | 16篇 |
1990年 | 20篇 |
1989年 | 30篇 |
1988年 | 26篇 |
1987年 | 20篇 |
1986年 | 21篇 |
1985年 | 14篇 |
1984年 | 10篇 |
1983年 | 8篇 |
1982年 | 12篇 |
1981年 | 10篇 |
1980年 | 10篇 |
1979年 | 8篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1976年 | 9篇 |
1975年 | 4篇 |
1967年 | 4篇 |
排序方式: 共有1268条查询结果,搜索用时 15 毫秒
1.
2.
The thymus is populated by various Ia+ cell populations, including epithelial cells, macrophages and dendritic cells. Thymic cell suspensions were stained with an anti-Ia antibody and shown by cytofluorometry to contain a small number of strongly Ia+ cells characterized by a large diameter. The cell population was separated with the aid of the fluorescence-activated cell sorter (FACS) and characterized. They were shown to express high levels of membranal Ia antigens; they demonstrated ATPase activity and displayed the ultrastructural features characteristic of the previously described thymic interdigitating cells. C57BL/6 mice were submitted to various regimens of X-irradiation. Whereas exposure to a single dose of X-irradiation was followed by an increase in the percentage of strongly Ia+ cells, exposure to a leukemogenic regimen of fractionated X-irradiation led to a decrease in the percentage and absolute numbers of these cells in the thymus. Of the C57BL/6 mice that were irradiated with fractionated X-irradiation, 77% developed leukemia. Intravenous injection of syngeneic bone marrow one day following the last irradiation or protection of the femur during irradiation prevented both the appearance of leukemia and the disappearance of interdigitating cells. Therefore an inverse correlation between the presence of thymic dendritic cells and the incidence of leukemia in C57BL/6 mice could be demonstrated. These findings are discussed in relation to the putative role of dendritic cells in the thymus. 相似文献
3.
4.
5.
6.
The effect of in vitro infection with herpes simplex virus 1 (HSV-1) on the Interleukin-1 (IL-1) activity of murine keratinocytes was investigated. IL-1 alpha mRNA synthesis was measured by the Northern blot technique, and the IL-1 protein production was measured in terms of the ability of dialysed supernatants from cultures of uninfected and HSV-1 infected keratinocytes to enhance mitogen-induced murine thymocyte proliferation. IL-1 alpha mRNA-synthesis in uninfected keratinocytes was detected 24 h and 48 h after isolation of the keratinocytes. IL-1 protein secretion by these keratinocytes was measureable at 18 h and reached a peak of 73 h, whereas intracellular and membrane-bound IL-1 protein production reached a maximum after 25 h. Keratinocytes, which had been cultured in vitro for 18 h, were infected with HSV-1 for 2 h and further cultured for an additional 4 h or 22 h before IL-1 measurements. A marked reduction of IL-1 alpha gene-expression was noted 6 hours after HSV-1-infection of keratinocytes, and nearly total shut-off was detected after infection for 24 h. Reduced gene-expression was paralleled by a reduction in the IL-1 protein secretion from the HSV-1 infected keratinocytes. 相似文献
7.
8.
INVOLVEMENT OF NON-NMDA AND NMDA RECEPTORS IN GLUTAMATE-INDUCED PRESSOR OR DEPRESSOR RESPONSES OF THE PONS AND MEDULLA 总被引:1,自引:0,他引:1
SY Chen WC Wu CJ Tseng JS Kuo CY Chai 《Clinical and experimental pharmacology & physiology》1997,24(1):46-56
1. Fifty-five intact and six baroreceptor denervated and vagotomized cats of either sex were anaesthetized intraperito-neally with urethane (400 mg/kg) and a-chloralose (40 mg/kg). Responses of the systemic arterial pressure (SAP), mean SAP (MSAP) and sympathetic vertebral nerve (VNA) and renal nerve activities (RNA) were recorded. 2. In intact animals, monosodium L-glutamate (Glu, 0.1 mol/L, 50 nL) was microinjected into pressor areas of the locus coeruleus (LC), gigantocellular tegmental field (GTF), rostral ventrolateral medulla (RVLM) and dorsomedial medulla (DM), and the depressor areas of caudal ventrolateral medulla (CVLM). The induced actions were compared before and after microinjection of either glutamate antagonists, glutamate diethylester (GDEE, 0.5 mol/L, 50–100nL), a competitive AMPA receptor blocker, or 2-amino-5-phosphonovaleric acid (D-AP5, 0.025 mol/L, 50–100 nL), a competitive N-methyl-D-aspartate (NMDA) receptor blocker. GDEE completely blocked the increases of SAP and VNA elicited from all pressor areas. D-AP5 only partially blocked the pressor but slightly blocked VNA and RNA responses from LC, GTF and DM, particularly those from RVLM. Neither GDEE nor D-AP5 blocked the depressor responses of SAP and two nerve activities elicited from CVLM. 3. In baroreceptor denervated animals, NMDA (2 mmol/L, 50–100 nL) and AMPA (0.2 mmol/L, 50–100 nL) were micro-injected into the same pressor areas of GTF, RVLM and DM and the depressor area of CVLM responsive to Glu activation (0.1 mol/L, 30 nL). In RVLM, DM and CVLM, the results of either NMDA or AMPA were similar to those induced by Glu. However, in GTF, microinjection of either NMDA or AMPA did not induce similar responses to Glu. This suggests that the nature of GTF may differ from RVLM and DM. 4. The above results suggest that the Glu-induced pressor responses from LC, GTF, DM and especially RVLM, are primarily mediated through AMPA receptors. The Glu-induced depressor responses from CVLM may not be predominantly mediated by either AMPA or NMDA receptors. 5. In both baroreceptor-intact and -denervated cats stimulation of the pressor areas often produced an increase of VNA and a decrease of RNA, while in the depressor CVLM decreased both VNA and RNA. The VNA, but not RNA were positively correlated with the pressor responses, while both VNA and RNA were positively correlated with the depressor responses. This may suggest that neurons of the sympathetic vertebral and renal nerves are topographically organized in the brain. 相似文献
9.
10.