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   216篇
  免费   22篇
  国内免费   1篇
电工技术   2篇
化学工业   75篇
金属工艺   6篇
机械仪表   3篇
建筑科学   4篇
能源动力   15篇
轻工业   58篇
石油天然气   1篇
无线电   10篇
一般工业技术   36篇
冶金工业   17篇
自动化技术   12篇
  2024年   1篇
  2023年   2篇
  2022年   16篇
  2021年   21篇
  2020年   15篇
  2019年   7篇
  2018年   5篇
  2017年   15篇
  2016年   16篇
  2015年   10篇
  2014年   8篇
  2013年   10篇
  2012年   12篇
  2011年   15篇
  2010年   17篇
  2009年   8篇
  2008年   14篇
  2007年   7篇
  2006年   7篇
  2005年   4篇
  2004年   4篇
  2003年   5篇
  2002年   4篇
  2001年   3篇
  2000年   2篇
  1999年   1篇
  1998年   2篇
  1996年   1篇
  1995年   1篇
  1994年   3篇
  1987年   1篇
  1975年   1篇
  1971年   1篇
排序方式: 共有239条查询结果,搜索用时 15 毫秒
1.
Ves-Losada A  Maté SM  Brenner RR 《Lipids》2001,36(3):273-282
Liver nuclear incorporation of stearic (18∶0), linoleic (18∶2n−6), and arachidonic (20∶4n−6) acids was studied by incubation in vitro of the [1-14C] fatty acids with nuclei, with or without the cytosol fraction at different times. The [1-14C] fatty acids were incorporated into the nuclei as free fatty acids in the following order: 18∶0>20∶4n−6≫18∶2n−6, and esterified into nuclear lipids by an acyl-CoA pathway. All [1-14C] fatty acids were esterified mainly to phospholipids and triacylglycerols and in a minor proportion to diacylglycerols. Only [1-14C] 18∶2n−6-CoA was incorporated into cholesterol esters. The incorporation was not modified by cytosol addition. The incorporation of 20∶4n−6 into nuclear phosphatidylcholine (PC) pools was also studied by incubation of liver nuclei in vitro with [1-14C]20∶4n−6-CoA, and nuclear labeled PC molecular species were determined. From the 15 PC nuclear molecular species determined, five were labeled with [1-14C]20∶4n−6-CoA: 18∶0–20∶4, 16∶0–20∶4, 18∶1–20∶4, 18∶2–20∶4, and 20∶4–20∶4. The highest specific radioactivity was found in 20∶4–20∶4 PC, which is a minor species. In conclusion, liver cell nuclei possess the necessary enzymes to incorporate exogenous saturated and unsaturated fatty acids into lipids by an acyl-CoA pathway, showing specificity for each fatty acid. Liver cell nuclei also utilize exogenous 20∶4n−6-CoA to synthesize the major molecular species of PC with 20∶4n−6 at the sn-2 position. However, the most actively synthesized is 20∶4–20∶4 PC, which is a quantitatively minor component. The labeling pattern of 20∶4–20∶4 PC would indicate that this molecular species is synthesized mainly by the de novo pathway.  相似文献   
2.
Consider a distributed system N in which each agent has an input value and each communication link has a weight. Given a global function, that is, a function f whose value depends on the whole network, the goal is for every agent to eventually compute the value f (N). We call this problem global function computation. Various solutions for instances of this problem, such as Boolean function computation, leader election, (minimum) spanning tree construction, and network determination, have been proposed, each under particular assumptions about what processors know about the system and how this knowledge can be acquired. We give a necessary and sufficient condition for the problem to be solvable that generalizes a number of well-known results (Attyia et al. in J ACM 35(4):845–875, 1988; Yamashita and Kameda in IEEE Trans Parallel Distrib Syst 7(1):69–89, 1996; Yamashita and Kameda in IEEE Trans Parallel Distrib Syst 10(9):878–887, 1999). We then provide a knowledge-based (kb) program (like those of Fagin et al. (Reasoning about knowledge, MIT Press, Cambridge, 1995, Distrib Comput 10(4):199–225, 1997)) that solves global function computation whenever possible. Finally, we improve the message overhead inherent in our initial kb program by giving a counterfactual belief-based program (Halpern and Moses in Distrib Comput 17(2):91–106, 2004) that also solves the global function computation whenever possible, but where agents send messages only when they believe it is necessary to do so. The latter program is shown to be implemented by a number of well-known algorithms for solving leader election.  相似文献   
3.
Nowadays, one of the main challenges in factory planning is the consistent and coherent information modelling along planning processes. Despite the current efforts in the fields of virtual production as well as digital and virtual factory, planning and simulation applications mostly support only the analysis and the optimisation of single planning aspects. However, to match nowadays challenges, planners require solutions that provide an integrated view to evaluate planning scenarios in advance and to achieve increasing production quality and efficiency. The concept of virtual production intelligence (VPI) provides a basic concept for such an integrative information system that enables planners to integrate, to aggregate and to analyse data gathered during one planning project as well as to compare different projects. In this study, we present such an information system for factory planning using the concept of the VPI. The focus lies in particular on the information modelling as well as the information integration and evaluation. Therefore, the study presents theoretical basics and implementations of the VPI platform within a precise application scenario in factory planning. This is to process and provide a consolidated information base along the whole planning process to support factory planning projects.  相似文献   
4.
5.
Proenkephalin (PENK) and prodynorphin (PDYN) are endogenous opioid peptides mainly produced in the striatum and, to a lesser extent, in the cerebral cortex. Dysregulated metabolism and altered cerebrospinal fluid (CSF) levels of PENK and PDYN have been described in several neurodegenerative diseases. However, no study to date investigated these peptides in the CSF of sporadic Creutzfeldt–Jakob disease (sCJD). Using liquid chromatography-multiple reaction monitoring mass spectrometry, we evaluated the CSF PDYN- and PENK-derived peptide levels in 25 controls and 63 patients with sCJD belonging to the most prevalent molecular subtypes (MM(V)1, VV2 and MV2K). One of the PENK-derived peptides was significantly decreased in each sCJD subtype compared to the controls without a difference among subtypes. Conversely, PDYN-derived peptides were selectively decreased in the CSF of sCJD MV2K, a subtype with a more widespread overall pathology compared to the sCJD MM(V)1 and the VV2 subtypes, which we confirmed by semiquantitative analysis of cortical and striatal neuronal loss and astrocytosis. In sCJD CSF PENK and PDYN were associated with CSF biomarkers of neurodegeneration but not with clinical variables and showed a poor diagnostic performance. CSF PDYN and PENK-derived peptides had no significant diagnostic and prognostic values in sCJD; however, the distinct marker levels between molecular subtypes might help to better understand the basis of phenotypic heterogeneity determined by divergent neuronal targeting.  相似文献   
6.
7.
Computational simulations are used for the optimization of production processes in order to significantly reduce the need for costly experimental optimization approaches. Yet individual simulations can rarely describe more than a single production step. A set of simulations has to be coupled to each other to form a contiguous representation of a process chain. Eventually, simulated results have to be analyzed by domain experts to gather insight from the preformed computations. In this paper, we propose an IT infrastructure and software tools that aim at a rather non-intrusive way of coupling resources and domain expert’s knowledge to enable the collaborative setup, execution and analysis of distributed simulation chains. We illustrate the approach in the domain of materials processing. Beyond means originating from the domain of GRID computing for resource management, a data integration component assures semantic data integrity between the simulation steps and stores simulation data in an application independent way. Thus, we can transform this data into native formats for each simulation tool, and finally into a format that allows for contiguous visualizations and an intuitive, comprehensive analysis of complete simulated process chains.  相似文献   
8.
[Correction Notice: An erratum for this article was reported in Vol 3(1) of Psychological Trauma: Theory, Research, Practice, and Policy (see record 2010-26899-001). There were citation errors in the last sentence of the first column of text on page 9, and a reference was omitted from the reference list. The sentence should have read: “This result is consistent with other work that has found support for the anxious and dissociative reaction associated with trauma among Latinos and how it may relate to “ataque de nervios” (Hinton, Chong, Pollack, Barlow, & McNally, 2008; Lewis-Fernandez et al., 2002; Schechter et al., 2000; Tolin, Robinson, Gaztambide, Horowitz, & Blank, 2007).] [Correction Notice: An erratum for this article was reported in of Psychological Trauma: Theory, Research, Practice, and Policy (see record 2010-26899-001). In the original article there were citation errors in the last sentence of the first column of text on page 9, and a reference was omitted from the reference list. The sentence should have read: “This result is consistent with other work that has found support for the anxious and dissociative reaction associated with trauma among Latinos and how it may relate to “ataque de nervios” (Hinton, Chong, Pollack, Barlow, & McNally, 2008; Lewis-Fernandez et al., 2002; Schechter et al., 2000; Tolin, Robinson, Gaztambide, Horowitz, & Blank, 2007).] Research on the victimization of Latino women and the subsequent psychological impact has been limited by focusing on individual forms of victimization, primarily partner violence or sexual assault. Another deficiency includes mainly using convenience and/or geographically restricted samples, which impacts the generalizability of the results. To overcome these research limitations, the Sexual Assault Among Latinas (SALAS) study aimed to evaluate the broader scope of victimization among Latino women. The study surveyed a national sample of 2,000 Latino women using random digit dial methodology. Women were asked about various forms of victimization in childhood and adulthood including physical assaults, sexual assaults, stalking, threats, and witnessed violence, as well as psychological symptomatology including depression, anxiety, anger, and dissociation. This analysis found that victimized women were more likely to experience some form of polyvictimization and/or revictimization throughout their lives, with only 36% of victimized women experiencing one form of victimization in childhood or adulthood alone. Furthermore, multiple victimization experiences significantly increased the proportion of women who experienced psychological distress symptoms in the clinical range. For almost all evaluated symptoms, the multiple forms of victimization or varying victimization patterns significantly predicted clinical levels of psychological distress over any specific form or single incident of victimization. The results suggest that victimized Latino women experience multiple forms of victimization and that the evaluation of a broader spectrum of victimization better accounts for pathological symptomatology. Clinical implications for Latino women and future research directions are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
9.
The proteins streptavidin and avidin were electrochemically detected in solution by adsorptive transfer stripping square wave voltammetry (AdTS SWV) at a carbon paste electrode (CPE). AdTS SWV was used to quantify biotinylated oligonucleotides, DNA hybridizations, and avidin in extracts of transgenic avidin maize. The detection limits of denatured and native streptavidin were 6 pM and 120 nM, respectively. The results demonstrated that streptavidin/avidin AdTS SWV is a sensitive and specific method for quantifying DNA and proteins in biological samples such as foods and tissue extracts, including genetically modified crops (avidin maize) and other plants in neighboring fields.  相似文献   
10.
The aim of this work was to study the biogenic amine content of brine‐ripened cheeses after one year of storage and then to investigate possible contaminating micro‐organisms with decarboxylase activity. The biogenic amine production of isolates was tested in vitro. The most frequent biogenic amines were putrescine, histamine and tyramine. The biogenic amine content detected in one cheese sample was above 120 mg/kg; this can be considered toxicologically relevant. Decarboxylase activity was found for 33 contaminating micro‐organisms. Isolates belonging to Bacillus licheniformis, Debaryomyces hansenii, Staphylococcus equorum and Serratia marcescens produced significant amounts of putrescine and cadaverine.  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