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   299篇
  免费   20篇
  2024年   1篇
  2023年   2篇
  2022年   8篇
  2021年   16篇
  2020年   11篇
  2019年   8篇
  2018年   10篇
  2017年   4篇
  2016年   13篇
  2015年   21篇
  2014年   16篇
  2013年   32篇
  2012年   25篇
  2011年   27篇
  2010年   6篇
  2009年   12篇
  2008年   10篇
  2007年   12篇
  2006年   11篇
  2005年   6篇
  2004年   5篇
  2003年   11篇
  2002年   4篇
  2001年   8篇
  2000年   3篇
  1999年   2篇
  1998年   2篇
  1997年   3篇
  1996年   1篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1992年   2篇
  1989年   2篇
  1988年   1篇
  1987年   1篇
  1986年   5篇
  1985年   3篇
  1984年   4篇
  1982年   1篇
  1979年   2篇
  1978年   1篇
  1977年   1篇
  1973年   1篇
  1971年   1篇
  1967年   1篇
排序方式: 共有319条查询结果,搜索用时 15 毫秒
31.
32.
Rarefaction of the renal microvasculature correlates with declining kidney function. However, current technologies commonly used for its evaluation are limited by their reliance on endothelial cell antigen expression and assessment in two dimensions. We set out to establish a widely applicable and unbiased optical sectioning method to enable three dimensional imaging and reconstruction of the renal microvessels based on their luminal filling. The kidneys of subtotally nephrectomized (SNx) rats and their sham-operated counterparts were subjected to either routine two-dimensional immunohistochemistry or the novel technique of fluorescent microangiography (FMA). The latter was achieved by perfusion of the kidney with an agarose suspension of fluorescent polystyrene microspheres followed by optical sectioning of 200 μm thick cross-sections using a confocal microscope. The fluorescent microangiography method enabled the three-dimensional reconstruction of virtual microvascular casts and confirmed a reduction in both glomerular and peritubular capillary density in the kidneys of SNx rats, despite an overall increase in glomerular volume. FMA is an uncomplicated technique for evaluating the renal microvasculature that circumvents many of the limitations imposed by conventional analysis of two-dimensional tissue sections.  相似文献   
33.
We conducted a longitudinal study of cryptosporidiosis from birth to three years of age in an urban slum of Dhaka Bangladesh. Fecal DNA was extracted from monthly surveillance samples and diarrheal stool samples collected from 392 infants from birth to three years. A pan-Cryptosporidium qPCR assay was used to identify sub-clinical and symptomatic cryptosporidiosis. Anthropometric measurements were collected quarterly to assess child nutritional status. 31% (121/392) of children experienced a single and 57% (222/392) multiple infections with Cryptosporidium. Repeat infections had a lower burden of parasites in the stool (Cq slope = -1.85; p<0.0001) and were more likely to be sub-clinical (Chi square test for trend; p = 0.01). Repeat infections were associated with the development of growth faltering (Pearson correlation = -0.18; p = 0.0004). High levels of fecal IgA antibodies against the Cryptosporidium Cp23 sporozoite protein at one year of life were associated with a delay in reinfection and amelioration of growth faltering through three years of life (HAZ IgA high responders -1.323 ± 0.932 versus HAZ -1.731 ± 0.984 p = 0.0001). We concluded that nonsterile immunity to cryptosporidiosis in young children was associated with high levels of mucosal IgA anti-Cp23 and protection from diarrhea and growth faltering.Trial Registration: NCT02764918.  相似文献   
34.
35.
Wastewater-grown duckweed may be safely used as fish feed   总被引:2,自引:0,他引:2  
Duckweed has been used for the treatment of wastewater and as fish feed. A comparative study was carried out to determine (i) the efficacy of duckweed in treating hospital-based wastewater and (ii) the level of the microbial contamination of fish fed on wastewater-grown duckweed. There were two groups of ponds where fish farming was done. In one group of ponds (control ponds), duckweed that was grown using artificial fertilizer was used as fish feed; in another group (study ponds), wastewater-grown duckweed was used as fish feed. The faecal contamination of water, duckweed, and fish from study and control ponds were monitored by faecal coliform estimation. The presence of enteric pathogens among handlers, water, duckweed, and fish samples was also examined. It was observed that the faecal coliform counts of raw wastewater were 4.7 Log10 CFU/mL, which was reduced to <1 Log10 CFU/mL after treating with duckweed. There was no significant difference (P > 0.05) in faecal coliform counts in water collected from duckweed ponds and fish ponds of study and control areas. The wastewater-grown duckweed did not pose any health hazard to the handlers. These results demonstrated that the wastewater-treated duckweed may be safely used as fish feed.  相似文献   
36.
To examine whether cardioprotection initiated by reactive oxygen species (ROS) is dependent on protein kinase Cepsilon (PKCepsilon), isolated buffer-perfused mouse hearts were randomized to four groups: 1) antimycin A (AA) (0.1 microg/ml) for 3 min followed by 10 min washout and then 30 min global ischemia (I) and 2 h reperfusion (R); 2) controls of I/R alone; 3) AA bracketed with 13 min of N-2-mercaptopropionyl- glycine (MPG) followed by I/R; and 4) MPG (200 microM) alone, followed by I/R. Isolated adult rat ventricular myocytes (ARVM) were exposed to AA (0.1 microg/ml), and lucigenin was used to measure ROS production. Murine hearts and ARVM were exposed to AA (0.1 microg/ml) with or without MPG, and PKCepsilon translocation was measured by cell fractionation and subsequent Western blot analysis. Finally, the dependence of AA protection on PKCepsilon was determined by the use of knockout mice (-/-) lacking PKCepsilon. AA exposure caused ROS production, which was abolished by the mitochondrial uncoupler mesoxalonitrile 4-trifluoromethoxyphenylhydrazone. In addition, AA significantly reduced the percent infarction-left ventricular volume compared with control I/R (26 +/- 4 vs. 43 +/- 2%; P < 0.05). Bracketing AA with MPG caused a loss of protection (52 +/- 7 vs. 26 +/- 4%; P < 0.05). AA caused PKCepsilon translocation only in the absence of MPG, and protection was lost on the pkcepsilon(-/-) background (38 +/- 3 vs. 15 +/- 4%; P < 0.001). AA causes ROS production, on which protection and PKCepsilon translocation depend. In addition, protection is absent in PKCepsilon null hearts. Our results imply that, in common with ischemic preconditioning, PKCepsilon is crucial to ROS-mediated protection.  相似文献   
37.
A disintegrin and metalloprotease 10 (ADAM10) is a ubiquitous transmembrane metalloprotease that cleaves the extracellular regions from over 40 different transmembrane target proteins, including Notch and amyloid precursor protein. ADAM10 is essential for embryonic development and is also important in inflammation, cancer, and Alzheimer disease. However, ADAM10 regulation remains poorly understood. ADAM10 is compartmentalized into membrane microdomains formed by tetraspanins, which are a superfamily of 33 transmembrane proteins in humans that regulate clustering and trafficking of certain other transmembrane “partner” proteins. This is achieved by specific tetraspanin-partner interactions, but it is not clear which tetraspanins specifically interact with ADAM10. The aims of this study were to identify which tetraspanins interact with ADAM10 and how they regulate this metalloprotease. Co-immunoprecipitation identified specific ADAM10 interactions with Tspan5, Tspan10, Tspan14, Tspan15, Tspan17, and Tspan33/Penumbra. These are members of the largely unstudied TspanC8 subgroup of tetraspanins, all six of which promoted ADAM10 maturation. Different cell types express distinct repertoires of TspanC8 tetraspanins. Human umbilical vein endothelial cells express relatively high levels of Tspan14, the knockdown of which reduced ADAM10 surface expression and activity. Mouse erythrocytes express predominantly Tspan33, and ADAM10 expression was substantially reduced in the absence of this tetraspanin. In contrast, ADAM10 expression was normal on Tspan33-deficient mouse platelets in which Tspan14 is the major TspanC8 tetraspanin. These results define TspanC8 tetraspanins as essential regulators of ADAM10 maturation and trafficking to the cell surface. This finding has therapeutic implications because focusing on specific TspanC8-ADAM10 complexes may allow cell type- and/or substrate-specific ADAM10 targeting.  相似文献   
38.
The endocannabinoid system is highly implicated in the development of insulin resistance associated with obesity. It has been shown that antagonism of the CB(1) receptor improves insulin sensitivity (S(I)). However, it is unknown whether this improvement is due to the direct effect of CB(1) blockade on peripheral tissues or secondary to decreased fat mass. Here, we examine in the canine dog model the longitudinal changes in S(I) and fat deposition when obesity was induced with a high-fat diet (HFD) and animals were treated with the CB(1) antagonist rimonabant. S(I) was assessed (n = 20) in animals fed a HFD for 6 wk to establish obesity. Thereafter, while HFD was continued for 16 additional weeks, animals were divided into two groups: rimonabant (1.25 mg·kg(-1)·day(-1) RIM; n = 11) and placebo (n = 9). Euglycemic hyperinsulinemic clamps were performed to evaluate changes in insulin resistance and glucose turnover before HFD (week -6) after HFD but before treatment (week 0) and at weeks 2, 6, 12, and 16 of treatment (or placebo) + HFD. Magnetic resonance imaging was performed to determine adiposity- related changes in S(I). Animals developed significant insulin resistance and increased visceral and subcutaneous adiposity after 6 wk of HFD. Treatment with RIM resulted in a modest decrease in total trunk fat with relatively little change in peripheral glucose uptake. However, there was significant improvement in hepatic insulin resistance after only 2 wk of RIM treatment with a concomitant increase in plasma adiponectin levels; both were maintained for the duration of the RIM treatment. CB(1) receptor antagonism appears to have a direct effect on hepatic insulin sensitivity that may be mediated by adiponectin and independent of pronounced reductions in body fat. However, the relatively modest effect on peripheral insulin sensitivity suggests that significant improvements may be secondary to reduced fat mass.  相似文献   
39.
A lectin was purified (designated as TCSL) from the Snake guard seeds with molecular mass of 56±2 kDa containing two subunits (34±1 and 22±1 kDa.). TCSL exhibited high agglutination activity at the temperature range 30 to 70°C and did not lose its activity between pH 3.0 to 12.0. The lectin was stable in the presence of denaturants and agglutinated mouse, goat, cow, chicken and human erythrocytes. TCSL did not show antifungal activity whereas it agglutinated six pathogenic bacteria and showed less toxicity against brine shrimp nauplii with the LC50 of 261±29 μg/ml. TCSL showed 28% and 72% inhibition against Ehrlich ascites carcinoma (EAC) cells in vivo in mice when administered 1 mg/kg/day and 2 mg/kg/day (i.p.) respectively for five days. TCSL enhanced the number of macrophages remarkably in the normal mice. The lectin reduced the tumor burden to 62% of EAC cells and significantly increased the hemoglobin and RBC. Treating the EAC bearing mice with TCSL at 2 mg/Kg/day for ten days with a monitoring of 20 days decreased the total WBC towards the normal level and it increased the life span by 39%.  相似文献   
40.
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