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   957篇
  免费   155篇
  国内免费   10篇
耳鼻咽喉   15篇
儿科学   93篇
妇产科学   13篇
基础医学   91篇
口腔科学   40篇
临床医学   158篇
内科学   218篇
皮肤病学   9篇
神经病学   39篇
特种医学   162篇
外科学   127篇
综合类   34篇
预防医学   39篇
眼科学   1篇
药学   30篇
中国医学   5篇
肿瘤学   48篇
  2022年   2篇
  2021年   11篇
  2020年   6篇
  2019年   6篇
  2018年   35篇
  2017年   43篇
  2016年   37篇
  2015年   34篇
  2014年   36篇
  2013年   63篇
  2012年   28篇
  2011年   25篇
  2010年   61篇
  2009年   53篇
  2008年   30篇
  2007年   28篇
  2006年   22篇
  2005年   13篇
  2004年   11篇
  2003年   16篇
  2002年   10篇
  2001年   18篇
  2000年   8篇
  1999年   7篇
  1998年   59篇
  1997年   53篇
  1996年   55篇
  1995年   49篇
  1994年   28篇
  1993年   40篇
  1992年   16篇
  1991年   18篇
  1990年   21篇
  1989年   17篇
  1988年   24篇
  1987年   22篇
  1986年   15篇
  1985年   11篇
  1984年   13篇
  1983年   17篇
  1982年   3篇
  1981年   17篇
  1980年   8篇
  1978年   2篇
  1977年   10篇
  1976年   9篇
  1975年   4篇
  1974年   2篇
  1965年   1篇
  1938年   1篇
排序方式: 共有1122条查询结果,搜索用时 15 毫秒
121.

Background

Breast cancer (BC) represents one of the leading causes of cancer related deaths worldwide. New tools for diagnostic staging and therapeutic monitoring are needed to improve individualized therapies and improve clinical outcome. The analyses of circulating tumour cells may provide important prognostic information in the clinical setting.

Materials and methods

Circulating tumour cells (CTC) of 63 BC patients were isolated from peripheral blood (PB) through immunomagnetic separation. Subsequently, RT-PCR or mPCR for the genes ga733.2, muc-1, c-erbB2, mgb-1, spdef and c-erbB2 were performed. Subsequently, expression data were correlated with the tumour stages. Fourteen healthy individuals served as controls.

Results

Significant correlations with tumour stages were found in single gene analyses of ga733.2, muc-1 and in multi-gene analyses of ga733.2/muc-1/mgb1/spdef. Furthermore, a significant correlation of Ca 15-3 and all studied genes was also observed.

Conclusion

Herein, we demonstrated a positive correlation of a gene signature consisting of ga733.2, muc-1, mgb1 and spdef and advanced stages of BC. Moreover, all studied genes and gene patterns revealed a significant correlation with Ca 15-3 positive cases.  相似文献   
122.
123.

Background and purpose:

In vitro evidence suggests that metabolism of anandamide by cyclooxygenase-2 (COX-2) may be more important when the primary metabolic pathway [i.e. fatty acid amide hydrolase (FAAH)] is inhibited. Thus, the first aim of the present study was to assess the effects of COX-2 and/or FAAH inhibition, on the cardiovascular actions of anandamide. The second aim was to compare the effects of anandamide with those of the metabolically stable analogue (i.e. methanandamide) and investigate mechanisms involved in responses to the latter in conscious rats.

Experimental approach:

Rats were chronically instrumented for recording blood pressure, heart rate and renal, mesenteric and hindquarters vascular conductances in the freely moving state.

Key results:

Inhibition of FAAH with URB597 (cyclohexycarbamic acid 3′-carbamoyl-biphenyl-3-yl-ester) augmented the haemodynamic actions of anandamide, but there was no effect of COX-2 inhibition with parecoxib, either in the absence or the presence of URB597. Methanandamide caused CB1 receptor-mediated renal and mesenteric vasoconstriction and evoked β2-adrenoceptor-mediated hindquarters vasodilatation.

Conclusions and implications:

No evidence for an involvement of COX-2 in the systemic cardiovascular actions of anandamide could be demonstrated. Vasoconstrictor actions of methanandamide were shown to involve CB1 receptors, whereas no involvement of CB1 receptors in such actions of anandamide has been shown. However, β2-adrenoceptor-mediated hindquarters vasodilatation, independent of CB1 receptors, observed here with methanandamide, has previously been seen with anandamide and differs from previous results with other synthetic cannabinoids for which the response was CB1 receptor-dependent. Thus, mechanisms underlying the cardiovascular actions of endocannabinoids and synthetic analogues appear to be agonist-specific.  相似文献   
124.

Background and purpose:

We compared the dose-dependent reductions in cellular superoxide anion (O2) by catalytic agents: superoxide dismutase (SOD), polyethylene glycol (PEG)-SOD and the nitroxide 4-hydroxy-2,2,6,6,-tetramethylpiperidine-1-oxyl (tempol) with uncharacterized antioxidants: 5,10,15,20-tetrakis (4-sulphonatophenyl) porphyrinate iron (III)(Fe-TTPS), (-)-cis-3,3′,4′,5,7-pentahydroxyflavane (2R,3R)-2-(3,4-dihydroxyphenyl)-3,4-dihydro-1(2H)-benzopyran-3,5,7-triol (-epicatechin), 2-phenyl-1,2-benzisoselenazol-3(2H)-one (ebselen) and N-acetyl-L-cysteine (NAC) with the spin trap nitroblue tetrazolium (NBT) and with the vitamins or their analogues: ascorbate, α-tocopherol and 6-hydroxy-2,5,7,8-tetramethylkroman-2-carboxy acid (trolox).

Experimental approach:

O2 was generated in primary cultures of angiotensin II-stimulated preglomerular vascular smooth muscle cells from spontaneously hypertensive rats and detected by lucigenin-enhanced chemiluminescence.

Key results:

SOD, PEG-SOD, NAC and tempol produced a similar maximum inhibition of O2 of 80–90%. -Epicatechin, NBT, ebselen and Fe-TTPS were significantly (P < 0.0125) less effective (50–70%), whereas trolox, α-tocopherol and ascorbate had little action even over 24 h of incubation (<31%). Effectiveness in disrupted and intact cells was similar for the permeable agents, PEG-SOD and tempol, but was enhanced for SOD. Generation of O2 was increased by NAC and NBT at low concentrations but reduced at high concentrations.

Conclusions and implications:

Maximum effectiveness against cellular production of O2 requires cell membrane permeability and catalytic action as exemplified by PEG-SOD or tempol. NAC and NBT have biphasic effects on O2 production. Vitamins C and E or analogues have low efficacy.  相似文献   
125.

Background  

Selective serotonin reuptake inhibitors (SSRIs), a popular class of antidepressants, may increase breast cancer risk by stimulating the secretion of prolactin, a potential tumour promoter. We evaluated the effects of duration of SSRI use, cumulative dose, and latency on the risk of breast cancer by conducting a population-based case-control study utilizing Saskatchewan health databases.  相似文献   
126.
This study shows a significant correlation between functional connectivity, as measured with resting-state functional magnetic resonance imaging (MRI), and neuroanatomical connectivity, as measured with manganese-enhanced MRI, in rats at 10 weeks after unilateral stroke and in age-matched controls. Reduced interhemispheric functional connectivity between the contralesional primary motor cortex (M1) and ipsilesional sensorimotor cortical regions was accompanied by a decrease in transcallosal manganese transfer from contralesional M1 to the ipsilesional sensorimotor cortex after a large unilateral stroke. Increased intrahemispheric functional connectivity in the contralesional sensorimotor cortex was associated with locally enhanced neuroanatomical tracer uptake, which underlines the strong link between functional and structural reorganization of neuronal networks after stroke.  相似文献   
127.
高压氧综合治疗糖尿病足的临床疗效观察   总被引:1,自引:0,他引:1  
糖尿病足(diabetic foot,DF)是常见的糖尿病慢性合并症之一,也是导致糖尿病人截肢致残的主要原因.近年来,糖尿病患病率逐年增高,使糖尿病足的患病率也呈逐年上升的趋势.  相似文献   
128.
129.
130.
Blunt traumatic aortic rupture: detection with helical CT of the chest   总被引:7,自引:1,他引:6  
  相似文献   
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