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   2414篇
  免费   53篇
  国内免费   80篇
电工技术   81篇
技术理论   1篇
综合类   153篇
化学工业   68篇
金属工艺   49篇
机械仪表   229篇
建筑科学   147篇
矿业工程   25篇
能源动力   96篇
轻工业   27篇
水利工程   22篇
石油天然气   61篇
武器工业   16篇
无线电   152篇
一般工业技术   70篇
冶金工业   98篇
原子能技术   39篇
自动化技术   1213篇
  2023年   8篇
  2022年   17篇
  2021年   20篇
  2020年   31篇
  2019年   19篇
  2018年   20篇
  2017年   24篇
  2016年   19篇
  2015年   50篇
  2014年   120篇
  2013年   93篇
  2012年   109篇
  2011年   135篇
  2010年   138篇
  2009年   104篇
  2008年   108篇
  2007年   149篇
  2006年   150篇
  2005年   154篇
  2004年   129篇
  2003年   97篇
  2002年   109篇
  2001年   76篇
  2000年   56篇
  1999年   55篇
  1998年   76篇
  1997年   58篇
  1996年   41篇
  1995年   38篇
  1994年   32篇
  1993年   30篇
  1992年   31篇
  1991年   27篇
  1990年   18篇
  1989年   24篇
  1988年   13篇
  1987年   7篇
  1986年   11篇
  1985年   12篇
  1984年   14篇
  1983年   15篇
  1982年   7篇
  1981年   13篇
  1980年   12篇
  1979年   12篇
  1978年   12篇
  1977年   4篇
  1976年   11篇
  1975年   13篇
  1973年   4篇
排序方式: 共有2547条查询结果,搜索用时 15 毫秒
111.
Yozo Takeda  Hamido Fujita 《Knowledge》2004,17(7-8):283-302
Based on the comparative review of several approaches to legacy system conversion and revitalization, the Lyee methodology application for the issue is presented to clarify its idea, the associated procedure, and the implemented tools. It could be said that with the tools and manual developed by ICBSM&T, the mechanical transformation of the conventional program to a Lyee-structured one becomes possible as long as the programs are made in a procedure-oriented language. In addition to the program structure conversion, the Lyee methodology permits people to choose any application language in the transformed program. At the same time, quite a new approach related to the system conversion is introduced, in which the chunk of data extracted from an old program is edited to make a new conventional structure program that has a logical sequence instead of a Lyee type of declarative program. These features can be realized through the concept of LyeeBELT, which is a set of word-information about the attributes, formulae, and conditions for an independent data item.

The overall workflow of the legacy program transformation is shown in the following.

A critical part in its implementation is the feasibility study (pre-analysis) stage where necessary information is supposed to be secured, and an appropriate plan and policy about the system to be revitalized in the new system environment should be clarified so as to customize the tools accordingly. If the initial process is completed, the mechanical legacy system conversion will be realized by registering the parameters in the tool, and the reestablishment of business knowledge in the LyeeBELT will be enabled. With the regulated business logic on the LyeeBELT, the program maintenance afterwards becomes drastically simplified and stable without the ‘spaghetti’ problem, so that software evolution can be possible.  相似文献   

112.
Fractal symbolic analysis is a symbolic analysis technique for verifying the legality of program transformations. It is strictly more powerful than dependence analysis; for example, it can be used to verify the legality of blocking LU factorization with pivoting, a task for which dependence analysis is inadequate. In this paper, we show how fractal symbolic analysis can be used to convert between left- and right-looking versions of three kernels of central importance in computational science: triangular solve, Cholesky factorization, and LU factorization with pivoting.  相似文献   
113.
Four years of longitudinal data from 373 families participating in a randomized intervention-control clinical trial were used to examine whether intervention effects on adolescent alcohol and tobacco use trajectories were moderated by family risk, as defined by parental social emotional maladjustment. Consistent with earlier outcome evaluations based on analyses of covariance, analyses confirmed that both the Preparing for the Drug Free Years program and the Iowa Strengthening Families Program favorably influenced alcohol use index trajectories across the time frame of the study; only the latter program, however, evidenced positive effects on a tobacco use index. Concerning the primary research question, analyses provided no support for family risk moderation of any intervention effect. Findings indicate the feasibility of developing universal preventive interventions that offer comparable benefits to all families. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
114.
徐琳  刘志勇  刘克  肖人毅 《软件学报》2004,15(10):1574-1581
给出了国家自然科学基金委员会信息科学部计算机科学处2003年12月份结题的面上项目评价结果,同时还给出了信息科学部面上项目结题评价指标,以供基金项目承担人及基金项目申请者参考.  相似文献   
115.
徐琳  刘志勇  刘克 《软件学报》2004,15(11):1741-1748
对2004年度国家自然科学基金委员会信息科学部计算机科学处面上项目的申请和资助情况进行了总结和分析,并与2003年度申请项目的数量以及资助金额进行了比较,同时给出了今年的评审原则,指出了今年面上基金申请中存在的问题,提出了适当的建议.  相似文献   
116.
We bridge the gap between compositional evaluators and abstract machines for the lambda-calculus, using closure conversion, transformation into continuation-passing style, and defunctionalization of continuations. This article is a followup of our article at PPDP 2003, where we consider call by name and call by value. Here, however, we consider call by need.We derive a lazy abstract machine from an ordinary call-by-need evaluator that threads a heap of updatable cells. In this resulting abstract machine, the continuation fragment for updating a heap cell naturally appears as an ‘update marker’, an implementation technique that was invented for the Three Instruction Machine and subsequently used to construct lazy variants of Krivine's abstract machine. Tuning the evaluator leads to other implementation techniques such as unboxed values. The correctness of the resulting abstract machines is a corollary of the correctness of the original evaluators and of the program transformations used in the derivation.  相似文献   
117.
《核技术(英文版)》2016,(2):122-130
An improvement for application of Dancoff factor is developed. It combines Stamm'ler's two-term method for resonance integral calculation with neutron current method for Dancoff factor calculation. Stamm'ler's formulation, which is originally derived for the infinite lattice geometry, can be easily revised to contain the Dancoff factor explicitly, while the neutron current method can easily calculate the Dancoff factor for general irregular assembly geometry. For the resonance interference effects the resonance interference factor table is built in pairs of nuclides, only for the interference between 238 U and other resonance nuclides, spanning over a range of background cross-section and number density ratio of the pairing nuclides. A series of verification calculations have been carried out for problems of infinite lattice and single assembly geometry, with two or multiple resonance absorbers. For these verification calculations, our improvement on Dancoff factor application and resonance interference give good results.  相似文献   
118.
A concern can be characterized as a developer׳s intent behind a piece of code, often not explicitly captured in it. We discuss a technique of recording concerns using source code annotations (concern annotations). Using two studies and two controlled experiments, we seek to answer the following 3 research questions: (1) Do programmers׳ mental models overlap? (2) How do developers use shared concern annotations when they are available? (3) Does using annotations created by others improve program comprehension and maintenance correctness, time and confidence? The first study shows that developers׳ mental models, recorded using concern annotations, overlap and thus can be shared. The second study shows that shared concern annotations can be used during program comprehension for the following purposes: hypotheses confirmation, feature location, obtaining new knowledge, finding relationships and maintenance notes. The first controlled experiment with students showed that the presence of annotations significantly reduced program comprehension and maintenance time by 34%. The second controlled experiment was a differentiated replication of the first one, focused on industrial developers. It showed a 33% significant improvement in correctness. We conclude that concern annotations are a viable way to share developers׳ thoughts.  相似文献   
119.
1200kt/a乙烯改扩建工程是大庆石化公司"十一五"发展的重点工程。文中以该工程的工艺及热力管网改造项目为例,从工程概况、材料计划、施工方案编制、过程经营、成本控制、风险防范等方面,探讨了管网改造项目的实施方案。  相似文献   
120.
I. J. Good 《技术计量学》2013,55(4):925-928
In this paper we have obtained, following Craig's procedure, a simplified form for the ASN of a single sampling plan under curtailment arising from observation of enough nondefectives to accept a lot or enough defectives to reject a lot.  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