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   1260篇
  免费   70篇
  国内免费   3篇
  2024年   2篇
  2023年   31篇
  2022年   48篇
  2021年   93篇
  2020年   97篇
  2019年   122篇
  2018年   83篇
  2017年   48篇
  2016年   82篇
  2015年   44篇
  2014年   90篇
  2013年   96篇
  2012年   83篇
  2011年   92篇
  2010年   36篇
  2009年   44篇
  2008年   34篇
  2007年   52篇
  2006年   38篇
  2005年   31篇
  2004年   27篇
  2003年   15篇
  2002年   10篇
  2001年   2篇
  2000年   1篇
  1999年   2篇
  1998年   3篇
  1997年   6篇
  1995年   4篇
  1994年   1篇
  1992年   2篇
  1989年   1篇
  1988年   2篇
  1986年   1篇
  1983年   2篇
  1982年   2篇
  1980年   1篇
  1977年   1篇
  1974年   2篇
  1949年   1篇
  1938年   1篇
排序方式: 共有1333条查询结果,搜索用时 31 毫秒
81.
82.
High-density lipoprotein (HDL) function rather than level may better predict cardiovascular disease (CVD). However, the contribution of the impaired antioxidant function of HDL that is associated with increased HDL lipid peroxidation (HDLox) to the development of clinical CVD remains unclear. We have investigated the association between serum HDLox with incident CVD outcomes in Mashhad cohort. Three-hundred and thirty individuals who had a median follow-up period of 7 years were recruited as part of the cohort. The primary end point was cardiovascular event, including myocardial infarction, stable angina, unstable angina, or coronary revascularization. In both univariate/multivariate analyses adjusted for traditional CVD risk factors, HDLox was an independent risk factor for CVD (odds ratio, 1.62; 95% confidence interval, 1.41–1.86; p < 0.001). For every increase in HDLox by 0.1 unit, there was an increase in CVD risk by 1.62-fold. In an adjusted analysis, there was a >2.5-fold increase in cardiovascular risk in individuals with HDLox higher than cutoff point of 1.06 compared to those with lower scores, suggesting HDLox > 1.06 is related to the impaired HDL oxidant function and in turn exposed to elevated risk of CVD outcomes (hazard ratio, 2.72; 95% CI, 1.88–3.94). Higher HDLox is a surrogate measure of reduced HDL antioxidant function that positively associated with cardiovascular events in a population-based cohort.  相似文献   
83.
Coal is one of the most important sources of fossil energy on earth. However, direct combustion of coal with a high sulfur content can cause various environmental problems. Other constituents of coal that can cause environmental problems include iron oxide (hematite), iron hydroxide, and silica. In this study, growing and resting cells of Rhodococcus erythropolis strains PD1, R1, and FMF, and R. qingshengii were used in heterotrophic removal of sulfur and bioleaching of iron and silica from coal. All of the mentioned strains have an ability of dibenzothiophene (DBT) desulfurization via 4-S pathway. 2-hydroxybiphenyl, sulfate, and ferric ions (Fe3+) were assayed by Gibb’s test, barium chloride (BaCl2), and thiocyanate ions (SCN?), respectively. FTIR and XRF analyzer were used for detection of the coal bioleaching process by the selected strain of R. erythropolis (PD1). Results indicated that all strains have the ability to grow on coal as the sulfur source. Among them, strain PD1 produced the highest optical density and continued to grow even after 150-h incubation. In both growing- and resting-cells experiments, strain PD1 desulfurized coal most readily compared to other strains. Results of XRF showed that growing cells of strain PD1 had high desulfurizing ability of coal (46%) compared to resting cells in the absence of any carbon sources (24%). Growing cells of strain PD1 also leached 46% of the iron and 14% of the silicate after 7?days of incubation. Resting cells of PD1 leached 32% of the iron as determined by XRF analysis. Also, growing cells of PD1 removed most SiO2 from coal as detected and confirmed by FTIR and XRF. To the best of our knowledge, this is the first report on bioleaching of iron and silica from coal by R. erythropolis strain PD1, making it a suitable candidate for coal bioremediation.  相似文献   
84.
Biological Trace Element Research - The prevalence of hypertension (HTN) is increasing globally. It has been shown that there is an association between micronutrient deficiency and HTN. In the...  相似文献   
85.
Molecular Biology Reports - Olanzapine (OLA), is prescribed as an anti-psychotic medicine in schizophrenia patients. In this study, the protective effect of OLA against genotoxicity&nbsp;and...  相似文献   
86.
This paper addresses the geometrical, charge, topological, and thermochemical data for the adsorption of the relevant furan species during hydrogenation of furfural to furfuryl alcohol over Cu/SiO2 and Cu/MgO catalysts. The calculations indicated that the binding of Cu to magnesia was stronger than that on silica. The results also indicated that the formation of an alkoxide intermediate is more favoured than that of a hydroxyalkyl species. The binding energetic data were in general agreement with the geometrical parameters, electron densities, and molecular orbital energy levels. The QTAIM data revealed the closed-shell interactions between Cu and O atoms on both of the catalysts. Finally, the analysis of the partial charges on the atoms revealed that the Cu atom acquires a positive charge upon interaction with the carbonyl group owing to a π-back-donation from Cu to the C?=?O bond.  相似文献   
87.
Rheumatoid arthritis (RA) is known as one of important autoimmune disorders which can lead to joint pain and damage throughout body. Given that internal (ie, genetic and epigenetic alterations) and external factors (ie, lifestyle changes, age, hormones, smoking, stress, and obesity) involved in RA pathogenesis. Increasing evidence indicated that cellular and molecular alterations play critical roles in the initiation and progression of RA. Among various targets and molecular signaling pathways, microRNAs (miRNAs) and their regulatory networks have key roles in the RA pathogenesis. It has been showed that deregulation of many miRNAs involved in different stages of RA. Hence, identification of miRNAs and their signaling pathways in RA, could contribute to new knowledge which help to better treatment of patients with RA. Besides miRNAs, exosomes have been emerged as key messengers in RA pathogenesis. Exsosomes are nanocarriers which could be released from various cells and lead to changing of behaviors recipient cells via targeting their cargos (eg, proteins, messenger RNAs, miRNAs, long noncoding RNAs, DNAs). Here, we summarized several miRNAs involved in RA pathogenesis. Moreover, we highlighted the roles of exosomes in RA pathogenesis.  相似文献   
88.
CD20 molecule, a phosphoprotein with 297 amino acids and four transmembrane domains, is a member of MS4A protein family. Anti-CD20 antibodies such as ofatumumab, which have been developed for cancer treatment and has demonstrated efficacy in relapsed/refractory chronic lymphocytic leukemia, are among the most successful therapies to date. Rational engineering methods can be applied with reasonable success to improve functional characteristics of antibodies. Considering the importance of this issue, we have used in silico modeling approach for the improvement of ofatumumab monoclonal antibody. Four mutated variants of ofatumumab were developed and expressed in Chinese hamster ovary (CHO) cells along with the unmodified antibody. Analysis of affinity of the purified antibodies with CD20 showed significant improvement in antigen-binding characteristics of one of the variants compared with the control antibody. This study represents the first step toward development of the second generation ofatumumab antibody with improved affinity.  相似文献   
89.
Coronary artery disease (CAD) is a multicellular disease characterized by chronic inflammation. Peripheral blood-mononuclear cells (PBMCs), as a critical component of immune system, actively cross-talk with pathophysiological conditions induced by endothelial cell injury, reflecting in perturbed PBMC expression. STAT1 is believed to be relevant to CAD pathogenesis through regulating key inflammatory processes and modulating STAT1 expression play key roles in fine-tuning CAD-related inflammatory processes. This study evaluated PBMC expressions of STAT1, and its regulators (miR-150 and miR-223) in a cohort including 72 patients with CAD with significant ( ≥ 50%) stenosis, 30 patients with insignificant ( < 50%) coronary stenosis (ICAD), and 74 healthy controls, and assessed potential of PBMC expressions to discriminate between patients and controls. We designed quantitative real-time polymerase chain reaction (RT-qPCR) assays and identified stable reference genes for normalizing PBMC quantities of miR-150, miR-223, and STAT1 applying geNorm algorithm to six small RNAs and five mRNAs. There was no significant difference between CAD and ICAD patients regarding STAT1 expression. However, both groups of patients had higher levels of STAT1 than healthy controls. miR-150 and miR-223 were differently expressed across three groups of subjects and were downregulated in patients compared with healthy controls, with the lowest expression levels being observed in patients with ICAD. ROC curves suggested that PBMC expressions may separate between different groups of study subjects. PBMC expressions also discriminated different clinical manifestations of CAD from ICADs or healthy controls. In conclusion, the present study reported PBMC dysregulations of STAT1, miR-150, and miR-223, in patients with significant or insignificant coronary stenosis and suggested that these changes may have diagnostic implications.  相似文献   
90.
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