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   1475篇
  免费   45篇
  国内免费   2篇
电工技术   10篇
化学工业   283篇
金属工艺   38篇
机械仪表   18篇
建筑科学   48篇
矿业工程   3篇
能源动力   26篇
轻工业   121篇
水利工程   43篇
石油天然气   28篇
无线电   121篇
一般工业技术   234篇
冶金工业   374篇
原子能技术   14篇
自动化技术   161篇
  2021年   20篇
  2020年   11篇
  2019年   17篇
  2018年   21篇
  2017年   24篇
  2016年   27篇
  2015年   18篇
  2014年   28篇
  2013年   99篇
  2012年   51篇
  2011年   83篇
  2010年   64篇
  2009年   49篇
  2008年   59篇
  2007年   55篇
  2006年   55篇
  2005年   43篇
  2004年   47篇
  2003年   51篇
  2002年   34篇
  2001年   24篇
  2000年   30篇
  1999年   15篇
  1998年   29篇
  1997年   44篇
  1996年   30篇
  1995年   27篇
  1994年   30篇
  1993年   23篇
  1992年   33篇
  1991年   23篇
  1990年   26篇
  1989年   24篇
  1988年   28篇
  1987年   16篇
  1986年   19篇
  1985年   14篇
  1984年   16篇
  1983年   22篇
  1982年   18篇
  1981年   19篇
  1980年   20篇
  1979年   12篇
  1978年   10篇
  1977年   12篇
  1976年   10篇
  1975年   15篇
  1974年   7篇
  1973年   13篇
  1970年   9篇
排序方式: 共有1522条查询结果,搜索用时 15 毫秒
991.
This article examined the impact of relationship closeness on the self-serving bias (SSB). Members of relationally distant dyads working on interdependent-outcomes tasks manifested the SSB: They took credit for dyadic success but blamed the partner for dyadic failure. However, members of relationally close dyads did not manifest the SSB: They did not take more credit than their partner for dyadic success and did not blame the partner more than the self for dyadic failure. This gracious attributional pattern of relationally close dyed members is due, at least in part, to formation of a favorable impression of the partner. Relationship closeness acts as a bound to an individual's self-enhancing tendencies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
992.
993.
编者按 越来越多的公司认识到缩减IT维护和运营成本,从而获得更多资金进行创新的重要性.戴尔商用服务器高级经理Glenn Keels在公司官方BLOG上贴文,以戴尔将30个数据中心缩减为2个的亲身实践现身说法.  相似文献   
994.
基于设计的分级将来自设计数据的版图信息与检测到的每个缺陷的相对位置结合起来,利用这种方法可提高缺陷帕雷托质量。通过对系统缺陷和有害缺陷进行分级,可以改进SEM检测。  相似文献   
995.
The KOPIO experiment at the BNL AGS required an extracted proton beam in which a debunched, coasting beam is forced between empty longitudinal RF buckets to form microbunches. The goal of the measurement described here was to obtain a low background determination of the fraction of protons coming from the AGS slowly extracted beam at times between microbunches (interbunch extinction). The effect on interbunch extinction of variations in the RF cavity voltage, the momentum dispersion of the beam and the main guide field voltage-ripple was studied. It was found that there exists a broad range of operating parameters that could allow the AGS to produce microbunches with the interbunch extinction better than the KOPIO experiment requirement. Results obtained in this study gave interbunch extinctions better than 10−5 (1%) of KOPIO's upper limit.  相似文献   
996.
Clinical examination to determine the dry weight of patients on hemodialysis (HD) has been problematic, with studies showing discordance between physician assessment and objective measures of volume status.We studied the association between predialysis bioimpedance spectroscopy (BIS)‐based estimates of fluid overload and postdialysis hypotension in 635 patients in the United States Renal Data System ACTIVE/ADIPOSE (A Cohort study To Investigate the Value of Exercise/Analyses Designed to Investigate the Paradox of Obesity and Survival in ESRD) study receiving HD in 2009–2011. We recorded predialysis and postdialysis weight and blood pressures over 3 consecutive HD sessions and performed BIS before a single session. Using a previously reported method of estimating normohydration weight, we estimated postdialysis fluid overload (FOpost) in liters. We used logistic regression with extracellular water/total body water (ECW/TBW) or estimated FOpost as the primary predictor and 1 or more postdialysis systolic blood pressures less than 110 mmHg as the dependent variable. Models were adjusted for age, sex, race, ultrafiltration rate per kilogram of body weight, end‐stage renal disease vintage, diabetes mellitus, heart failure, and albumin. Higher ECW/TBW was associated with lower odds of postdialysis hypotension (odds ratio [OR] 0.35, 95% confidence interval [CI] 0.15–0.84 per 0.1, P = 0.02). Every liter of FOpost was associated with lower adjusted odds of postdialysis hypotension (OR 0.86, 95% CI 0.79–0.95, P = 0.003). Prospective studies are needed to determine whether this application of BIS could improve current clinical efforts to minimize episodes of postdialysis hypotension without leading to volume overload.  相似文献   
997.
Sterol biosynthesis in the oyster,Crassostrea virginica, was examined by injection of [2-14C]acetate and [2,3-3H] lanosterol. The oyster incorporated [2-14C] acetate into squalene 4,4′-dimethylsterols, 4-monomethylsterols, cholesterol, desmosterol, isofucosterol, and 24-methylenecholesterol, and also converted [2-3H] lanosterol to cholesterol. Therefore, the oyster was concluded to synthesize cholesterol, desmosterol, isofucosterol, and 24-methylenecholesterol from acetate via squalene, probably using the lanosterol pathway.  相似文献   
998.
999.
Many scientific codes can achieve significant performance improvement when executed on a computer equipped with a vector processor. Vector constructs in source code should be recognized by a vectorizing compiler or preprocessor. This paper discusses, from a general point of view, how a vectorizing compiler/preprocessor can be evaluated. The areas discussed include data dependence analysis, IF loop analysis, nested loops, loop interchanging, loop collapsing, indirect addressing, use of temporary storage, and order of arithmetic. The ideas presented are based on vectorization of over a million lines of production codes and an extensive test suite developed to evaluate preprocessors under varying degrees of code complexity. Areas for future research are also discussed.  相似文献   
1000.
The Cocke-Younger-Kasami algorithm (CYK) always requires 0(n3) time and 0(n2) space to recognize a trial sentence ω = w1w2…wn, given an e-free context-free grammar in Chomsky Normal form. The same inductive rule that underlies the CYK algorithm may be used to produce a variant that computes the same information but requires (1) a maximum of 0(n3) time and 0(n2) space, and (2) only 0(s(n)) space and time for an unambiguous grammar, where s(n) is the number of triples (A,i,j) for which a nonterminal symbol A derives wiwi+1wi+j?1. In this case, time and space consumed are at worst 0(n2).It is shown in addition, for any grammar, that a parse may be obtained from the table left from the recognition algorithm in time 0(s(n)) whether or not the grammar is ambiguous. The same procedure for the CYK algorithm requires time 0(n2).The performance of our variant is quite similar to that of the Earley algorithm except that the Earley algorithm substitutes for s(n), a function which is usually smaller.The model we use of a RAM is strictly identical to the model used in the CYK algorithm. CR categories: 4.20, 5.23, 5.25.  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