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   600篇
  免费   22篇
电工技术   1篇
化学工业   134篇
金属工艺   11篇
机械仪表   11篇
建筑科学   47篇
矿业工程   1篇
能源动力   19篇
轻工业   83篇
水利工程   5篇
无线电   19篇
一般工业技术   69篇
冶金工业   145篇
自动化技术   77篇
  2023年   3篇
  2022年   2篇
  2021年   24篇
  2020年   11篇
  2019年   8篇
  2018年   15篇
  2017年   10篇
  2016年   12篇
  2015年   11篇
  2014年   16篇
  2013年   36篇
  2012年   28篇
  2011年   40篇
  2010年   20篇
  2009年   25篇
  2008年   31篇
  2007年   39篇
  2006年   24篇
  2005年   27篇
  2004年   15篇
  2003年   24篇
  2002年   27篇
  2001年   16篇
  2000年   10篇
  1999年   10篇
  1998年   14篇
  1997年   9篇
  1996年   8篇
  1995年   8篇
  1994年   11篇
  1993年   5篇
  1992年   5篇
  1991年   4篇
  1990年   4篇
  1989年   10篇
  1988年   6篇
  1987年   8篇
  1986年   7篇
  1985年   3篇
  1984年   2篇
  1983年   5篇
  1982年   5篇
  1981年   4篇
  1980年   4篇
  1979年   2篇
  1978年   3篇
  1977年   2篇
  1976年   3篇
  1975年   2篇
  1974年   2篇
排序方式: 共有622条查询结果,搜索用时 187 毫秒
31.
This paper provides a graphical approach for presenting results of a statistical test of average equivalence with process data. In addition, a graphical representation of process change in variance is presented. An example from the biopharmaceutical industry is provided to illustrate the information contained in the chart. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   
32.
White storks (Ciconia ciconia) fed in contaminated waters resulting from the Aznacollar acid mining-sludge spillage into the R. Guadiamar, which feeds the eastern flank of the Guadalquivir marshes (Do?ana), S.W. Spain. The sludge was rich in a range of toxic elements, and in organic pollutants such as the aromatic amines. Storks did not exhibit elevated metals in their blood immediately following the accident, but chick blood collected the year following the accident showed genotoxic damage compared to the controls. In this study lead isotope analysis was used to assess if the storks had ingested sludge-derived contaminants. The sludge lead isotope ratio was distinct from that of the Do?ana sediments. The stork blood lead isotope ratios exactly matched that of the sludge. It was concluded that the storks had ingested sludge-derived contaminants. A detailed study of the lead contamination along the R. Guadiamar and the R. Guadalquivir (of which the Guadiamar is a tributary) was also conducted to place the white stork colony lead exposure in the context of the spatial contamination of the storks' habitat.  相似文献   
33.
Pichia sorbitophila grows rapidly in the presence of very high NaCl concentrations. Under these conditions, even when the K(+) concentration is low, P. sorbitophila cells can maintain low Na(+) and high K(+) contents. This remarkable capacity of P. sorbitophila fails when the external pH is not acidic. This indicates that Na(+) efflux is mediated by an electroneutral Na(+)/H(+) antiporter. We have cloned and sequenced two genes designated as PsNHA1 and PsNHA2, which probably encode two antiporters of this type. The genes present high similarity with the corresponding genes from other yeasts. The heterologous expression of PsNHA1 or PsNHA2 in a Saccharomyces cerevisiae mutant lacking the Na(+) efflux systems and sensitive to high concentrations of Na(+) and K(+) rescued the tolerance and the ability to extrude both cations. The Accession Nos of the sequenced DNA fragments are: PsNHA1, AJ496431; PsNHA2, AJ496432. (TC 2.A.36) Copyright 2002 John Wiley & Sons, Ltd.  相似文献   
34.
As computer power increases, so too does the range of interesting biomolecular phenomena and properties that can be simulated. It is now possible to simulate complicated protein conformational changes at ambient or physiological temperatures. In this regard, we are attempting to map the conformational transitions of the normal, cellular prion protein (PrP(C)) to its infectious scrapie isoform (PrP(Sc)), which causes neurodegenerative diseases in many mammals. These two forms have identical sequences and are conformational isomers, with heightened formation of beta-sheet structure in the scrapie form. Conversion can be triggered by lowering the pH, but thus far it has been impossible to characterize the conformational change at high resolution using experimental methods. Therefore, to investigate the effect of acidic pH on PrP conformation, we have performed molecular-dynamics simulations of hamster, human and bovine forms of the prion protein in water at neutral and low pH. In all cases the core of the protein is well maintained at neutral pH. At low pH, however, the protein is more dynamic, and the sheet-like structure increases both by lengthening of the native beta-sheet and by addition of a portion of the N-terminus to widen the sheet by another 2-3 strands.  相似文献   
35.
A new method is presented to screen proteolytic mass maps of cross-linked protein complexes for the presence of cross-linked peptides and for the verification of proposed structures. On the basis of the incorporation of 18O from isotopically enriched water into the C-termini of proteolytic peptides, cross-linked peptides are readily distinguished in mass spectra by a characteristic 8 amu shift. This is due to the incorporation of two 18O atoms in each C-terminus, so that normal and surface-labeled peptides shift 4 amu and cross-linked peptides containing two C-termini will shift 8 amu compared with their unlabeled counterparts. The method is fast, sensitive, and reliable and can be combined with any available cross-linking reagent and a wide range of proteolytic agents. As proof of principle, we successfully applied the method to a complex of two DNA repair proteins (Rad18-Rad6) and identified the interaction domain.  相似文献   
36.
Despite training, professionals sometimes make serious errors in risky decision making. The authors investigated judgments and decisions for 9 hypothetical patients at 3 levels of cardiac risk, comparing student and physician groups varying in domain-specific knowledge. Decisions were examined regarding whether they deviated from guidelines, how risk perceptions and risk tolerances determined decisions, and how the latter differed for knowledge groups. More knowledgeable professionals were better at discriminating levels of risk according to external correspondence criteria but committed similar errors in disjunctive probability judgments, violating internal coherence criteria. Also, higher knowledge groups relied on fewer dimensions of information than did lower knowledge groups. Consistent with fuzzy-trace theory, experts achieved better discrimination by processing less information and made sharper all-or-none distinctions among decision categories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
37.
Alumina support material suitable for use as a planar automotive gas sensor support was coated in thin films of yttria-stabilised zirconia (YSZ) and titania. The morphology, composition, thickness and homogeneity of the coating was measured. The coating was applied to the ‘green’ form of a tape cast alumina substrate which was subsequently fired at 1500 °C to produce the final form of the coated alumina. The YSZ coating gave a continuous 5 μm thick coating with no evidence of mixed oxide formation between the YSZ and the alumina substrate. XRD indicated a face centred cubic Y doped ZrO2 or primitive tetragonal Zr0.9Y0.1O1.95 phase. The titania coatings were much thinner (<1 μm) with signs of trace amounts of aluminium titanium oxide (Al2TiO5) as well as rutile titania in XRD. Spot analysis using X-ray photoelectron spectroscopy showed a fairly regular titania coverage. Atomic force microscopy analysis showed a particle size of 1–3 μm for the YSZ coating and 0.5 μm for titania.  相似文献   
38.
39.
Constructed the Children's Self-Efficacy for Peer Interaction Scale (CSPI) and administered it to 245 3rd–5th graders along with the Piers-Harris Children's Self-Concept Scale and the Teacher Rating Scale of Social Efficacy. Analyses of reliability and construct validity indicated that the CSPI has psychometric properties that warrant its use. Ss' self-efficacy varied by grade and situation. The usefulness of the CSPI for research on children's social development is discussed. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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