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   1602篇
  免费   11篇
电工技术   5篇
化学工业   217篇
金属工艺   9篇
机械仪表   13篇
建筑科学   57篇
矿业工程   3篇
能源动力   6篇
轻工业   167篇
水利工程   14篇
石油天然气   3篇
无线电   37篇
一般工业技术   217篇
冶金工业   689篇
原子能技术   7篇
自动化技术   169篇
  2022年   16篇
  2021年   23篇
  2020年   15篇
  2019年   15篇
  2018年   9篇
  2017年   9篇
  2016年   21篇
  2015年   9篇
  2014年   23篇
  2013年   76篇
  2012年   44篇
  2011年   68篇
  2010年   48篇
  2009年   51篇
  2008年   58篇
  2007年   67篇
  2006年   76篇
  2005年   62篇
  2004年   58篇
  2003年   67篇
  2002年   57篇
  2001年   32篇
  2000年   22篇
  1999年   26篇
  1998年   42篇
  1997年   30篇
  1996年   50篇
  1995年   23篇
  1994年   30篇
  1993年   30篇
  1992年   27篇
  1991年   13篇
  1990年   32篇
  1989年   32篇
  1988年   25篇
  1987年   29篇
  1986年   28篇
  1985年   24篇
  1984年   34篇
  1983年   33篇
  1982年   15篇
  1981年   20篇
  1980年   17篇
  1979年   13篇
  1978年   22篇
  1977年   8篇
  1976年   13篇
  1975年   18篇
  1974年   13篇
  1973年   8篇
排序方式: 共有1613条查询结果,搜索用时 0 毫秒
81.
设计性能出色的全新3D电视可走终南捷径,赛灵思介绍了其Spartan-6 FPGA消费显示套件和IP,可为DisplayPort设计带来方便.  相似文献   
82.
Diagnosing diabetic nephropathy by 1H NMR metabonomics of serum   总被引:2,自引:0,他引:2  
Object: The most severe complication of type 1 diabetes (T1DM) is diabetic nephropathy. It is associated with a high risk of cardiovascular complications and premature death and requires early detection to be efficiently treated. The clinical practice to diagnose diabetic nephropathy is also a non-optimal and tedious set up based on albumin excretion rate in multiple overnight or 24h urine samples. Conversely, in this study, these independent diagnostic data are used to provide a realistic testing case for applying 1H NMR metabonomics of serum in a diagnostic fashion. Materials and Methods: 182 T1DM and 21 non-diabetic (non-T1DM) individuals were studied. The 1H NMR of serum at 500 MHz was targeted at two molecular windows: lipoprotein lipids and low-molecular-weight metabolites. Results: T1DM and non-T1DM individuals were exclusively separated by 1H NMR. For diabetic nephropathy diagnosis in the T1DM patients, 1H NMR data (and clinical biochemistry data) gave a sensitivity of 87.1% (83.9%) and a specificity of 87.7% (95.9%). The predictive values of positive and negative tests were 89.0% (95.5%) and 83.6% (79.2%), respectively. Conclusions: 1H NMR metabonomics clearly distinguishes metabolic characteristics of T1DM and appears approximately as good a means to diagnose diabetic nephropathy from serum as an advanced set of biochemical variables.  相似文献   
83.
Determining the structure of the (oligomeric) intermediates that form during the self-assembly of amyloidogenic peptides is challenging because of their heterogeneous and dynamic nature. Thus, there is need for methodology to analyze the underlying molecular structure of these transient species. In this work, a combination of fluorescence quenching, photo-induced crosslinking (PIC) and molecular dynamics simulation was used to study the assembly of a synthetic amyloid-forming peptide, Aβ16-22. A PIC amino acid containing a trifluormethyldiazirine (TFMD) group—Fmoc(TFMD)Phe—was incorporated into the sequence (Aβ*16–22). Electrospray ionization ion-mobility spectrometry mass-spectrometry (ESI-IMS-MS) analysis of the PIC products confirmed that Aβ*16–22 forms assemblies with the monomers arranged as anti-parallel, in-register β-strands at all time points during the aggregation assay. The assembly process was also monitored separately using fluorescence quenching to profile the fibril assembly reaction. The molecular picture resulting from discontinuous molecule dynamics simulations showed that Aβ16-22 assembles through a single-step nucleation into a β-sheet fibril in agreement with these experimental observations. This study provides detailed structural insights into the Aβ16-22 self-assembly processes, paving the way to explore the self-assembly mechanism of larger, more complex peptides, including those whose aggregation is responsible for human disease.  相似文献   
84.
Near infrared (NIR) is becoming a popular option for rapid cure of coatings in the coil coating industry particularly where fast line speeds are required. The technology has the potential to reduce the cure time of a 20 μm polyester coating on a galvanised steel substrate from around 30 s via conventional heating methods down to <10 s under the lamps. Previous work suggested that the ideal situation in this case is to have a topcoat which is slightly transparent to NIR and an absorbing substrate to heat the coating from the substrate outwards in a two stage process which separates solvent removal from cross linking and film formation. This can be taken further by tinting the primer layer with a pigment that absorbs in the NIR region. In this study spectroscopy was used to show that a coated steel system could appear white in the visible region because of the reflectance of TiO2 but the NIR absorption could be altered by adding absorbing pigments such as carbon black. Lamp settings could be reduced by 20% to achieve equivalent cure with tinted primer systems. The potential degradation in corrosion protection afforded by carbon-black containing pigments at various loadings was assessed for model organic coatings applied to galvanised steel specimens. In situ scanning Kelvin probe studies showed that rates of corrosion-driven coating delamination by cathodic disbondment remained unchanged by pigment loadings of up to 3.5 wt%.  相似文献   
85.
This study examined the contributions of four individual difference predictors to preschool children's recall for object names. Measures of object knowledge (the Peabody Picture Vocabulary Test [PPVT]), conceptual tempo (the Kansas Reflection-Impulsivity Scale for Preschoolers [KRISP] error scores), strategic study period activities, and teacher ratings of children's mastery motivation were used to predict recall scores of 3- and 4-year-old children. KRISP-error scores, strategic study activities, and motivation ratings were found to be significant correlates of recall. Motivation ratings entered a regression prediction equation first, followed by the strategic study activity measure, yielding a multiple correlation of .62. These predictors were unrelated, suggesting that motivational factors contributed to young children's recall proficiency directly, perhaps through greater task involvement and analysis and more effortful retrieval activity, and do not mediate strategic study behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
86.
Screen-printed layers of Al2O3, BaTiO3, 0.90Pb(Mg1/3Nb2/3)-03–0.10PbTiO3, Pb(Zr,Ti)O3, ZnO, and glass alumina pastes have been patterned using photoprinting techniques. Curability of each paste by ultraviolet light and formation of holes with various diameters were studied for application as a production method for very small-sized vias. The dependence of hole diameters on various experimental parameters is presented and discussed. Wall slopes were found to depend on the transmission of the powders used in the pastes.  相似文献   
87.
Following a midterm exam in an introductory psychology course, college students (N?=?189) were administered the same test items under nonevaluative conditions. The hypothesis that high-anxious individuals as compared with low-anxious individuals would retrieve a greater degree of information not previously available to them when they were assessed under reduced threat was only partially supported. However, easy-item performance provided some evidence for an interference phenomenon. An interaction indicated that previously blocked information became available only for those high-anxious students who had initially used effective study strategies. Path analysis confirmed the relative importance of anxiety phenomena to classroom test performance in a time-ordered causal network involving ability level, study effectiveness, and anxiety arousal. Results add credence to a recent interpretation of anxiety as a failure-of-self phenomenon. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
88.
It was hypothesized that age-related deficits in episodic memory for feature combinations (e.g., B. L. Chalfonte & M. K. Johnson, 1996) signal, in part, decrements in the efficacy of reflective component processes (e.g., M. K. Johnson, 1992) that support the short-term maintenance and manipulation of information during encoding (e.g., F. I. M. Craik, R. G. Morris, & M. L. Gick, 1990; T. A. Salthouse, 1990). Consistent with this, age-related binding deficits in a working memory task were found in 2 experiments. Evidence for an age-related test load deficit was also found: Older adults had greater difficulty than young adults when tested on 2 features rather than 1, even when binding was not required. Thus, disruption of source memory in older adults may involve deficits in both encoding processes (binding deficits) and monitoring processes (difficulty accessing multiple features, evaluating them, or both). (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
89.
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