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   16483篇
  免费   1800篇
  国内免费   1540篇
电工技术   640篇
综合类   1473篇
化学工业   180篇
金属工艺   109篇
机械仪表   655篇
建筑科学   192篇
矿业工程   90篇
能源动力   187篇
轻工业   59篇
水利工程   224篇
石油天然气   51篇
武器工业   74篇
无线电   3203篇
一般工业技术   980篇
冶金工业   128篇
原子能技术   28篇
自动化技术   11550篇
  2024年   69篇
  2023年   147篇
  2022年   207篇
  2021年   223篇
  2020年   357篇
  2019年   281篇
  2018年   278篇
  2017年   453篇
  2016年   513篇
  2015年   700篇
  2014年   927篇
  2013年   1199篇
  2012年   1173篇
  2011年   1310篇
  2010年   1007篇
  2009年   1286篇
  2008年   1344篇
  2007年   1377篇
  2006年   1163篇
  2005年   971篇
  2004年   856篇
  2003年   733篇
  2002年   592篇
  2001年   494篇
  2000年   379篇
  1999年   271篇
  1998年   258篇
  1997年   224篇
  1996年   154篇
  1995年   123篇
  1994年   115篇
  1993年   90篇
  1992年   87篇
  1991年   55篇
  1990年   38篇
  1989年   42篇
  1988年   45篇
  1987年   32篇
  1986年   28篇
  1985年   35篇
  1984年   49篇
  1983年   29篇
  1982年   21篇
  1981年   20篇
  1980年   21篇
  1979年   12篇
  1978年   7篇
  1977年   11篇
  1976年   9篇
  1975年   4篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
新落成的江苏广电城将即将投入使用,江苏广电网站搬入大楼全新的IDC机房。与广播、电视并列为江苏广电总台三大宣传阵地的广电网站由于受困于中国南北方网络瓶颈的限制,经常造成网络视音频节目传播不畅,所以同时接入电信和网通成为解决问题的必要手段。此文首先对IDC双线路关键技术进行了概述,然后着重介绍了根据防火墙接口地址制定策略路由、实现双线路的方法。  相似文献   
42.
We consider the sequencing of a series of jobs that arrive at a single processor over time. At each job’s arrival time, a due date must be quoted for the job, and the job must complete processing before its quoted due date. The objective is to minimize the sum (or average) of quoted due dates, or equivalently, the average quoted lead time. In this paper, we propose on-line heuristics for this problem and characterize the conditions under which these heuristics are asymptotically optimal. Computational testing further demonstrates the relative effectiveness of these heuristics under various conditions. Both authors made equal contributions to this paper and are listed in alphabetical order.  相似文献   
43.
The purpose of this paper is to stimulate interest within the civil engineering research community for developing the next generation of applied artificial neural networks. In particular, it identifies what the next generation of these devices needs to achieve, and provides direction in terms of how their development may proceed. An analysis of the current situation indicates that progress in the development of artificial neural network applications has largely stagnated. Suggestions are made for advancing the field to the next level of sophistication and application, using genetic algorithms and related techniques. It is shown that this approach will require the design of some very sophisticated genetic coding mechanisms in order to develop the required higher-order network structures, and will utilize development mechanisms observed in nature such as growth, self-organization, and multi-stage objective functions. The capabilities of such an approach and the way in which they can be achieved are explored with reference to the problems of: (a) determining truck attributes from the strain envelopes they induce in structural members when crossing a bridge, and; (b) developing a decision support system for dynamic control of industrialized manufacturing of houses.  相似文献   
44.
This paper contextualises, describes and discusses a student project which takes a particular exploratory approach to using mathematical surface definition as a language and vehicle for co-rational design co-authorship for architecture and engineering. The project has two authors, one from an architectural and one from an engineering educational background. It investigates the metaphorical and operational role of mathematics in the design process and outcomes.  相似文献   
45.
This paper is a review of the approachesdeveloped to solve 2D packing problems withmeta-heuristic algorithms. As packing tasks arecombinatorial problems with very large searchspaces, the recent literature encourages theuse of meta-heuristic search methods, inparticular genetic algorithms. The objective ofthis paper is to present and categorise thesolution approaches in the literature for 2Dregular and irregular strip packing problems.The focus is hereby on the analysis of themethods involving genetic algorithms. Anoverview of the methods applying othermeta-heuristic algorithms including simulatedannealing, tabu search, and artificial neuralnetworks is also given.  相似文献   
46.
The Journal of Supercomputing - Rapid advances in interconnection networks in multiprocessors are closing the gap between computation and communication. Given this trend, how can we utilize fast...  相似文献   
47.
This Mathematica 5.2 package1 is a simulation of a Quantum Computer. The program provides a modular, instructive approach for generating the basic elements that make up a quantum circuit. The main emphasis is on using the density matrix, although an approach using state vectors is also implemented in the package. The package commands are defined in Qdensity.m which contains the tools needed in quantum circuits, e.g., multiqubit kets, projectors, gates, etc. Selected examples of the basic commands are presented here and a tutorial notebook, Tutorial.nb is provided with the package (available on our website) that serves as a full guide to the package. Finally, application is made to a variety of relevant cases, including Teleportation, Quantum Fourier transform, Grover's search and Shor's algorithm, in separate notebooks: QFT.nb, Teleportation.nb, Grover.nb and Shor.nb where each algorithm is explained in detail. Finally, two examples of the construction and manipulation of cluster states, which are part of “one way computing” ideas, are included as an additional tool in the notebook Cluster.nb. A Mathematica palette containing most commands in QDENSITY is also included: QDENSpalette.nb.

Program summary

Title of program: QDENSITYCatalogue identifier: ADXH_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADXH_v1_0Program available from: CPC Program Library, Queen's University of Belfast, N. IrelandOperating systems: Any which supports Mathematica; tested under Microsoft Windows XP, Macintosh OS X, and Linux FC4Programming language used: Mathematica 5.2No. of bytes in distributed program, including test data, etc.: 180 581No. of lines in distributed program, including test data, etc.: 19 382Distribution format: tar.gzMethod of solution: A Mathematica package is provided which contains commands to create and analyze quantum circuits. Several Mathematica notebooks containing relevant examples: Teleportation, Shor's Algorithm and Grover's search are explained in detail. A tutorial, Tutorial.nb is also enclosed.  相似文献   
48.
49.
Exploring a polygon with robots when the robots do not have knowledge of the surroundings can be viewed as an online problem. Typical for online problems is that decisions must be made based on past events without complete information about the future. In our case the robots do not have complete information about the environment. Competitive analysis can be used to measure the performance of methods solving online problems. The competitive ratio of such a method is the ratio between the method's performance and the performance of the best method having full knowledge of the future. We prove constant competitive strategies and lower bounds for exploring a simple rectilinear polygon in the L1L1 metric.  相似文献   
50.
N. Gupta  S. Sen 《Algorithmica》2001,31(2):179-207
We describe an efficient parallel algorithm for hidden-surface removal for terrain maps. The algorithm runs in O(log 4 n) steps on the CREW PRAM model with a work bound of O((n+k) \polylog ( n)) where n and k are the input and output sizes, respectively. In order to achieve the work bound we use a number of techniques, among which our use of persistent data structures is somewhat novel in the context of parallel algorithms. Received July 29, 1998; revised October 5, 1999.  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