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   382篇
  免费   14篇
电工技术   2篇
综合类   1篇
化学工业   133篇
金属工艺   5篇
机械仪表   14篇
建筑科学   9篇
能源动力   14篇
轻工业   38篇
水利工程   3篇
石油天然气   1篇
无线电   32篇
一般工业技术   46篇
冶金工业   50篇
原子能技术   2篇
自动化技术   46篇
  2023年   6篇
  2022年   36篇
  2021年   34篇
  2020年   11篇
  2019年   7篇
  2018年   8篇
  2017年   5篇
  2016年   10篇
  2015年   15篇
  2014年   20篇
  2013年   23篇
  2012年   21篇
  2011年   25篇
  2010年   9篇
  2009年   13篇
  2008年   8篇
  2007年   19篇
  2006年   18篇
  2005年   6篇
  2004年   7篇
  2003年   7篇
  2002年   3篇
  2001年   2篇
  2000年   3篇
  1999年   1篇
  1998年   5篇
  1997年   5篇
  1996年   6篇
  1995年   7篇
  1994年   5篇
  1993年   5篇
  1992年   1篇
  1990年   1篇
  1989年   1篇
  1988年   3篇
  1987年   2篇
  1986年   2篇
  1985年   1篇
  1984年   8篇
  1983年   3篇
  1982年   7篇
  1981年   3篇
  1980年   5篇
  1979年   2篇
  1978年   2篇
  1977年   1篇
  1975年   1篇
  1972年   1篇
  1968年   1篇
  1961年   1篇
排序方式: 共有396条查询结果,搜索用时 0 毫秒
41.
Myocardial infarction is one of the leading causes of death worldwide, despite numerous efforts to find efficient prognostic biomarkers and treatment targets. In the present study, we aimed to assess the potential of six microRNAs known to be involved in cardiovascular diseases, cell-free DNA (cfDNA), and mitochondrial DNA (mtDNA) circulating in plasma to be used as prognostic tools for the occurrence of unfavorable outcomes such as major adverse cardiovascular events (MACE) after acute ST-segment elevation myocardial infarction (STEMI). Fifty STEMI patients were enrolled and monitored for 6 months for the occurrence of MACE. Plasma was collected at three time points: upon admission to hospital (T0), at discharge from hospital (T1), and 6 months post-STEMI (T6). Plasma levels of miR-223-3p, miR-142-3p, miR-155-5p, miR-486-5p, miR-125a-5p, and miR-146a-5p, as well as of cfDNA and mtDNA, were measured by RT-qPCR. Results showed that the levels of all measured miRNAs, as well as of cfDNA and mtDNA, were the most increased at T1, compared to the other two time points. In the plasma of STEMI patients with MACE compared to those without MACE, we determined increased levels of miRNAs, cfDNA, and mtDNA at T1. Hence, we used the levels of all measured parameters at T1 for further statistical analysis. Statistical analysis demonstrated that all six miRNAs and cfDNA plus mtDNA levels, respectively, were associated with MACE. The minimal statistical model that could predict MACE in STEMI patients was the combination of mtDNA and miR-142-3p levels, as evidenced by ROC analysis (AUC = 0.97, p < 0.001). In conclusion, the increased plasma levels of mtDNA, along with miR-142-3p, could be used to predict unfavorable outcomes in STEMI patients.  相似文献   
42.
43.
The lipophilic fluorescent probe diphenylhexatriene (DPH) has been shown previously to behave as a marker of plasma membrane in living cell systems, and it is therefore been widely used in membrane fluidity studies via fluorescence anisotropy measurements. The anisotropic coefficient, which is inversely related to the rotational motion of the probe in membrane phospholipids, was significantly higher at 37 degrees C than at 23 degrees C for 9 series of red blood cells ghosts obtained from three healthy subjects. We also have studied the importance of the nature of two different polaroid films which permits the observation of fluorescence polarization.  相似文献   
44.
We discuss some relationships between probability theory and statistics on one hand, and the theory of fuzzy sets on the other hand. We develop various statistical techniques for the analysis of imprecise data and for inference based on imprecise data. We study the estimation of fuzzy parameters, testing problems with fuzzy probabilities, and confidence estimation under uncertainty. Finally, we indicate some possible applications to the assessment of credibility in expert systems.  相似文献   
45.
The aim of this investigation was to determine whether the regioselectivity found for lipoxygenases in the formation of fatty acid hydroperoxides from linoleic acid is reflected in the formation of dimeric products in secondary reactions involving linoleic acid, product hydroperoxide and lipoxygenase. A method was therefore developed for the separation and identification of dimers formed by fusion of two linoleic acid radicals or a linoleic acid radical and linoleate. The method includes solid-phase extraction, preparative separation of products by thin-layer chromatography, derivatization to the corresponding fully hydrogenated methyl esters and capillary gas chromatography (GC) coupled with electron impact mass spectrometry. We present evidence that the formation of octadecadienoate dimers, during the secondary reaction of soybean lipoxygenase-1 or lipoxygenase-3, is a nonenzymic process that can be envisaged by nonspecific association of intermediate fatty acid radicals (L*) that have dissociated from the enzyme. We could show that the relative amounts of different octadecadienoate dimers formed remain unaltered, regard-less of pH and type of soybean isoenzyme used. Quantitative analysis by GC showed that under the reaction conditions used, the formation of dimers branching at the 13-position is preferred.  相似文献   
46.
47.
A review of M. Horner's (1968) study and subsequent research using the fantasy-based measure of fear of success suggested the following conclusions: Horner's results do not support the hypothesis that high-fear-of-success females perform poorly under competitive conditions; there are no reliable age or sex differences in motivation to avoid success; fear of success and sex role orientation appear to be unrelated; it is not clear whether the fear-of-success measure taps a motive or taps cultural stereotypes; there are no consistent relationships between fear of success and achievement-related variables; the reliability of the fear-of-success measure is low (probably in the .30-.40 range); and there are no consistent relationships between fear of success and any behavioral measures. It is suggested that future research will have to use new measures of fear of success. 3 such measures and preliminary findings are presented. (43 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
48.
Five experiments examined the effects of attribution, salience, and representativeness of a target person's behavior on consensus bias—the tendency to generalize from the target's behavior to the behavior of the group. Ss were 762 undergraduates. Exp I showed that actors and observers induced to make a situational attribution for a behavior perceived this behavior as more common than did those induced to make a dispositional attribution. Exps II and III showed that observers perceived salient behavior as more common in the group than nonsalient behavior. Exps IV and V showed that observers were more likely to generalize from the behavior of a representative target than from the behavior of a nonrepresentative target. It is concluded that attributes of the target's behavior exercise strong influence on consensus estimates. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
49.
Although long-chain fatty acyl-coenzyme A (LCFA-CoA) thioesters are specific high-affinity ligands for hepatocyte nuclear factor-4α (HNF-4α) and peroxisome proliferator-activated receptor-α (PPARα), X-ray crystals of the respective purified recombinant ligand-binding domains (LBD) do not contain LCFA-CoA, but instead exhibit bound LCFA or have lost all ligands during the purification process, respectively. As shown herein: (i) The acyl chain composition of LCFA bound to recombinant HNF-4α reflected that of the bacterial LCFA-CoA pool, rather than the bacterial LCFA pool. (ii) Bacteria used to produce the respective HNF-4α and PPARα contained nearly 100-fold less LCFA-CoA than LCFA. (iii) Under conditions used to crystallize LBD (at least 3 wk at room temperature in aqueous buffer), 16∶1-CoA was very unstable in buffer alone. (iv) In the presence of the respective nuclear receptor (i.e., HNF-4α and PPARα), LBD 70–75% of 16∶1-CoA was degraded after 1 d at room temperature in the crystallization buffer, whereas as much as 94–97% of 16∶1-CoA was degraded by 3 wk. (v) Cytoplasmic LCFA-CoA binding proteins such as acyl-CoA binding protein, sterol carrier protein-2, and liver-FA binding protein slowed the process of 16∶1-CoA degradation proportional to their respective affinities for this ligand. Taken together, these data for the first time indicated that the absence of LCFA-CoA in the crystallized HNF-4α and PPARα was due to the paucity of LCFA-CoA in bacteria as well as to the instability of LCFA-CoA in aqueous buffers and the conditions used for LBD crystallization. Furthermore, instead of protecting bound LCFA-CoA from autohydrolysis like several cytoplasmic LCFA-CoA binding proteins, these nuclear receptors facilitated LCFA-CoA degradation.  相似文献   
50.
Discusses several methodological, statistical, and interpretative problems in a study of interpersonal stress, facial expressivity, and physiological reactivity conducted by C. I. Notarius et al (see record 1983-05644-001). (2 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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