首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3202篇
  免费   224篇
  国内免费   28篇
耳鼻咽喉   15篇
儿科学   124篇
妇产科学   80篇
基础医学   350篇
口腔科学   121篇
临床医学   275篇
内科学   691篇
皮肤病学   35篇
神经病学   237篇
特种医学   163篇
外科学   492篇
综合类   136篇
一般理论   2篇
预防医学   216篇
眼科学   131篇
药学   118篇
中国医学   9篇
肿瘤学   259篇
  2023年   26篇
  2022年   38篇
  2021年   77篇
  2020年   58篇
  2019年   66篇
  2018年   73篇
  2017年   47篇
  2016年   62篇
  2015年   102篇
  2014年   119篇
  2013年   109篇
  2012年   187篇
  2011年   195篇
  2010年   124篇
  2009年   94篇
  2008年   164篇
  2007年   173篇
  2006年   199篇
  2005年   151篇
  2004年   156篇
  2003年   186篇
  2002年   123篇
  2001年   120篇
  2000年   110篇
  1999年   69篇
  1998年   55篇
  1997年   53篇
  1996年   37篇
  1995年   22篇
  1994年   31篇
  1993年   14篇
  1992年   35篇
  1991年   33篇
  1990年   39篇
  1989年   34篇
  1988年   35篇
  1987年   35篇
  1986年   38篇
  1985年   37篇
  1984年   23篇
  1983年   14篇
  1982年   14篇
  1981年   15篇
  1980年   5篇
  1979年   10篇
  1977年   9篇
  1975年   8篇
  1974年   4篇
  1973年   5篇
  1971年   5篇
排序方式: 共有3454条查询结果,搜索用时 0 毫秒
91.
92.
Acupuncture has been reported to be beneficial in treating cognitive impairment in various pathological conditions. This review describes the effort to understand the signaling pathways that underlie the acupunctural therapeutic effect on cognitive function. We searched the literature in 12 electronic databases from their inception to November 2013, with full text available and language limited to English. Twenty-three studies were identified under the selection criteria. All recruited animal studies demonstrate a significant positive effect of acupuncture on cognitive impairment. Findings suggest acupuncture may improve cognitive function through modulation of signaling pathways involved in neuronal survival and function, specifically, through promoting cholinergic neural transmission, facilitating dopaminergic synaptic transmission, enhancing neurotrophin signaling, suppressing oxidative stress, attenuating apoptosis, regulating glycometabolic enzymes and reducing microglial activation. However, the quality of reviewed studies has room for improvement. Further high-quality animal studies with randomization, blinding and estimation of sample size are needed to strengthen the recognition of group differences.  相似文献   
93.
94.
本研究以宁夏回族自治区为案例,针对村医经济激励水平低下,按项目付费引发不恰当诊治行为,系统内缺乏引导供方提高自身服务效率和质量并促进服务与体系整合协调的经济激励等问题,从供方合理激励的角度出发,对新型农村合作医疗支付制度进行改革设计——以乡村为整体对乡镇卫生院和村卫生室提供的门诊服务实施基于绩效的按人头预付制。随后利用配对整群随机试验设计对改革效果进行评估和检验。研究发现,这一支付制度的实施有效降低了农村基本医疗服务中抗生素的使用率,优化了供方的处方行为,对降低村卫生室的单次门诊费用有一定作用,并且促进服务向村卫生室下沉。本文的政策分析和设计思路及严格的政策评估结果可以为我国支付制度的选择和发展提供政策参考和证据支持。  相似文献   
95.
96.
Highly purified, Escherichia coli-derived recombinant human tumor necrosis factor (TNF) was labeled with 125I and employed to determine receptor binding, internalization, and intracellular degradation in murine L929 cells (highly sensitive to the cytotoxic action of TNF) and in diploid human FS-4 cells (resistant to TNF cytotoxicity). 125I-labeled TNF bound specifically to high-affinity receptors on both L929 and FS-4 cells. Scatchard analysis of the binding data indicated the presence of 2200 binding sites per L929 cell and 7500 binding sites per FS-4 cell. The calculated dissociation constants are 6.1 X 10(-10) M and 3.2 X 10(-10) M for L929 and FS-4 cells, respectively. In both L929 and FS-4 cells, incubation at 37 degrees C resulted in a rapid internalization of the bulk of the cell-bound TNF, followed by the appearance of trichloroacetic acid-soluble 125I radioactivity in the tissue culture medium, due to degradation of TNF. Degradation but not cellular uptake of TNF was inhibited in the presence of chloroquine (an inhibitor of lysosomal proteases) in both L929 and FS-4 cells, suggesting that degradation occurs intracellularly, probably within lysosomes. These results show that resistance of FS-4 cells to TNF cytotoxicity is not due to a lack of receptors or their inability to internalize and degrade TNF.  相似文献   
97.
98.
A complete experimental format is given for the reconstitution of human hemoglobin from the separated heme-free alpha- and beta-globin chains (alpha degrees, beta degrees) and hemin, by two alternative routes. Based on their oxygen binding properties, the reaction of the ferri-forms with reducing agent, and the response of the oxygen binding curves to pH variation and to the addition of the allosteric effector 2,3-diphosphoglycerate, the molecules are native. One reconstitution route uses direct addition of hemin to the separated globin chains with production of the separated subunits, which can then be recombined and reduced. This procedure occasions losses by precipitation in the heme-addition step except at high dilutions, and the yields are low. In the second pathway, either globin chain is mixed with the complementary untreated subunit to form the half-filled (with heme) intermediates, which combine stoichiometrically with hemin. No precipitation accompanies these reactions. For alpha-globin, the yield is about 50% because of incomplete combination with the heme-containing beta chain. For beta-globin, the yield is better than 70%. It is suggested that experiments intended to test either globin chain should use the second route in preparation for structural or functional comparisons with native hemoglobin.  相似文献   
99.
gamma (immune) interferon (IFN-gamma) was induced in cultures of fresh human lymphocytes by combined treatment with a phorbol ester (12-O-tetradecanoylphorbol 13-acetate, TPA) and the T cell mitogen phytohemagglutinin (PHA). Compared to the IFN-gamma yields obtained with PHA induction alone, the inclusion of TPA caused a significant enhancement of IFN-gamma production. Poly(A)-containing mRNA was isolated from mononuclear cells induced with TPA and PHA. Injected into Xenopus laevis oocytes, this mRNA preparation gave rise to IFN activity with characteristic properties of human IFN-gamma. Sucrose density gradient centrifugation analysis showed that IFN-gamma mRNA sedimented at 15 S, suggesting that it contains a total of about 1400 nucleotides.  相似文献   
100.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号