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   284篇
  免费   23篇
  2023年   2篇
  2022年   4篇
  2021年   14篇
  2020年   5篇
  2019年   5篇
  2018年   14篇
  2017年   11篇
  2016年   11篇
  2015年   15篇
  2014年   20篇
  2013年   16篇
  2012年   19篇
  2011年   29篇
  2010年   11篇
  2009年   13篇
  2008年   10篇
  2007年   10篇
  2006年   10篇
  2005年   9篇
  2004年   6篇
  2003年   6篇
  2002年   8篇
  2001年   8篇
  2000年   7篇
  1999年   5篇
  1998年   3篇
  1997年   3篇
  1996年   1篇
  1994年   2篇
  1993年   1篇
  1991年   5篇
  1990年   1篇
  1989年   2篇
  1988年   1篇
  1986年   2篇
  1985年   4篇
  1984年   2篇
  1983年   3篇
  1979年   2篇
  1976年   1篇
  1974年   2篇
  1972年   2篇
  1969年   1篇
  1966年   1篇
排序方式: 共有307条查询结果,搜索用时 15 毫秒
171.
172.
R Mulherkar  A Saraf  A Wagle  M G Deo 《FEBS letters》1986,207(1):142-144
A unique polypeptide, called enhancing factor (EF), which enhances the binding of labeled epidermal growth factor (EGF) to cells, has been isolated. It has been purified to homogeneity from the acid-soluble proteins of mouse intestines. Earlier, EF was partially purified by two cycles of gel-permeation chromatography on Bio-Gel columns. We now report the final purification of EF on high-performance liquid chromatography (HPLC), using a reverse-phase column (mu Bondapak C18). The purity of the protein was confirmed when a single peak was obtained in HPLC. Also, a single protein band was obtained in SDS-PAGE. Purified EF has the same properties in vitro as those reported earlier for partially purified EF.  相似文献   
173.
174.
175.
Atrial fibrillation (AF) is the most common sustained arrhythmia in patients with chronic kidney disease (CKD). In this study, we examined the association between inflammation and AF in 3,762 adults with CKD, enrolled in the Chronic Renal Insufficiency Cohort (CRIC) study. AF was determined at baseline by self-report and electrocardiogram (ECG). Plasma concentrations of interleukin(IL)-1, IL-1 Receptor antagonist, IL-6, tumor necrosis factor (TNF)-α, transforming growth factor-β, high sensitivity C-Reactive protein, and fibrinogen, measured at baseline. At baseline, 642 subjects had history of AF, but only 44 had AF in ECG recording. During a mean follow-up of 3.7 years, 108 subjects developed new-onset AF. There was no significant association between inflammatory biomarkers and past history of AF. After adjustment for demographic characteristics, comorbid conditions, laboratory values, echocardiographic variables, and medication use, plasma IL-6 level was significantly associated with presence of AF at baseline (Odds ratio [OR], 1.61; 95% confidence interval [CI], 1.21 to 2.14; P = 0.001) and new-onset AF (OR, 1.25; 95% CI, 1.02 to 1.53; P = 0.03). To summarize, plasma IL-6 level is an independent and consistent predictor of AF in patients with CKD.  相似文献   
176.
Vegetation characteristics were assessed at different distancesdownwind of an aluminium factory to elucidate changes in communityattributes. The importance value index (IVI) of sensitive speciesdecreased and those of tolerant species increased with the increasingpollution load around the factory. Plant community compositionchanged with distance from this source. Species richness andthe Shannon-Weiner index increased with the increasing distancefrom the source, while concentration of dominance declined from1 to 11 km. The similarity coefficient indicated that the thirdand fifth sites are closer to each other, and first and fourthsites are farthest. The shape of the species sequence vs. theIVI distribution curve slipped from the shape of log normaldistribution at sites receiving higher pollution load. The woodylayer is found to be more affected compared to the herbaceouslayer. The aluminium factory impact was most pronounced up to4 km downwind of the source. Data on ambient air quality werefound to be directly related to the unfavourable changes incommunity attributes.Copyright 1994, 1999 Academic Press Importance value index, aluminium factory, community attributes, herbaceous layer, woody layer, sensitive and tolerant species  相似文献   
177.
178.
For outdoor photobiological hydrogen production, the effective control of temperature in photobioreactors is a challenge. In this work, an internal cooling system for outdoor tubular photobioreactors was designed, built, and tested. The temperatures in the reactors with bacteria were consistently higher than those without bacteria, and were also strongly influenced by solar irradiation and ambient air temperature. The cooling protocol applied successfully kept the reactor temperatures below the threshold limit (38 °C) required for the bioprocess and provided a uniform distribution of temperature along the reactor tube length. The biomass growth and hydrogen production were similar in the reactors cooled co-currently and counter-currently. The biomass growth rate was 0.1 l/h, the maximum hydrogen production rate was 1.28 mol/m3/h, and the overall hydrogen yield obtained was 20 %. The change in the biomass was fitted using the logistic model while cumulative hydrogen production was fitted using the modified Gompertz equation.  相似文献   
179.
Raunaq A. Deo  William A. Prinz 《Cell》2021,184(14):3591-3592
  相似文献   
180.
Deficits in auditory processing are among the best documented endophenotypes in schizophrenia, possibly due to loss of excitatory synaptic connections. Dendritic spines, the principal post-synaptic target of excitatory projections, are reduced in schizophrenia. p21-activated kinase 1 (PAK1) regulates both the actin cytoskeleton and dendritic spine density, and is a downstream effector of both kalirin and CDC42, both of which have altered expression in schizophrenia. This study sought to determine if there is decreased auditory cortex PAK1 protein expression in schizophrenia through the use of quantitative western blots of 25 schizophrenia subjects and matched controls. There was no significant change in PAK1 level detected in the schizophrenia subjects in our cohort. PAK1 protein levels within subject pairs correlated positively with prior measures of total kalirin protein in the same pairs. PAK1 level also correlated with levels of a marker of dendritic spines, spinophilin. These latter two findings suggest that the lack of change in PAK1 level in schizophrenia is not due to limited sensitivity of our assay to detect meaningful differences in PAK1 protein expression. Future studies are needed to evaluate whether alterations in PAK1 phosphorylation states, or alterations in protein expression of other members of the PAK family, are present in schizophrenia.  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