全文获取类型
收费全文 | 5000篇 |
免费 | 300篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 63篇 |
综合类 | 8篇 |
化学工业 | 970篇 |
金属工艺 | 57篇 |
机械仪表 | 83篇 |
建筑科学 | 194篇 |
矿业工程 | 5篇 |
能源动力 | 162篇 |
轻工业 | 365篇 |
水利工程 | 56篇 |
石油天然气 | 38篇 |
无线电 | 406篇 |
一般工业技术 | 1225篇 |
冶金工业 | 671篇 |
原子能技术 | 15篇 |
自动化技术 | 991篇 |
出版年
2024年 | 13篇 |
2023年 | 61篇 |
2022年 | 99篇 |
2021年 | 150篇 |
2020年 | 116篇 |
2019年 | 128篇 |
2018年 | 129篇 |
2017年 | 139篇 |
2016年 | 171篇 |
2015年 | 141篇 |
2014年 | 194篇 |
2013年 | 343篇 |
2012年 | 323篇 |
2011年 | 396篇 |
2010年 | 309篇 |
2009年 | 292篇 |
2008年 | 321篇 |
2007年 | 257篇 |
2006年 | 224篇 |
2005年 | 196篇 |
2004年 | 156篇 |
2003年 | 145篇 |
2002年 | 137篇 |
2001年 | 72篇 |
2000年 | 69篇 |
1999年 | 64篇 |
1998年 | 61篇 |
1997年 | 54篇 |
1996年 | 59篇 |
1995年 | 51篇 |
1994年 | 50篇 |
1993年 | 40篇 |
1992年 | 45篇 |
1991年 | 25篇 |
1990年 | 29篇 |
1989年 | 17篇 |
1988年 | 16篇 |
1987年 | 30篇 |
1986年 | 16篇 |
1985年 | 31篇 |
1984年 | 15篇 |
1983年 | 7篇 |
1982年 | 16篇 |
1981年 | 21篇 |
1979年 | 7篇 |
1977年 | 7篇 |
1976年 | 11篇 |
1975年 | 7篇 |
1973年 | 9篇 |
1964年 | 6篇 |
排序方式: 共有5309条查询结果,搜索用时 0 毫秒
11.
Jonathan J. Cook 《Software》2004,34(9):815-845
We discuss P#, our implementation of a tool that allows interoperation between a concurrent superset of the Prolog programming language and C#. This enables Prolog to be used as a native implementation language for Microsoft's .NET platform. P# compiles a linear logic extension of Prolog to C# source code. We can thus create C# objects from Prolog and use C#'s graphical, networking and other libraries. We add language constructs on the Prolog side that allow concurrent Prolog code to be written. A primitive predicate is provided that evaluates a Prolog structure on a newly forked thread. Communication between threads is based on the unification of variables contained in such a structure. It is also possible for threads to communicate through a globally accessible table. All of the new features are available to the programmer through new built-in Prolog predicates. We discuss two software engineering tools implemented using P#. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
12.
We show new upper bounds for problems in the W-hierarchy of fixed-parameter complexity. A crucial ingredient of our proofs
is an extension to the W-RAM model, which permits more-powerful operations but remains equivalent to the original. We use
the extended model to give new upper bounds for Subsetsum, Maximum Irredundant Set, and various problems concerning intersection
of finite-state machines. 相似文献
13.
It is common knowledge today that application of sound manufacturing concepts and techniques will only provide cost-effective, long-term return when manufacturing functions are totally integrated with the operators, maintenance engineers and other associated personnel. This paper presents a human-centred methodology and its associated knowledge-based tool, to utilize equipment failure information for the purpose of machine down-time minimization. Based upon a structured and rigorous assessment of each breakdown, and combined with total employee participation, continuous improvement of maintenance function and operational effectiveness of equipment can be made a reality. 相似文献
14.
Xiao-Ying Wang Jonathan M. Garibaldi Benjamin Bird Michael W. George 《Applied Intelligence》2007,27(3):237-248
Recently Fourier Transform Infrared (FTIR) spectroscopic imaging has been used as a tool to detect the changes in cellular
composition that may reflect the onset of a disease. This approach has been investigated as a mean of monitoring the change
of the biochemical composition of cells and providing a diagnostic tool for various human cancers and other diseases. The
discrimination between different types of tissue based upon spectroscopic data is often achieved using various multivariate
clustering techniques. However, the number of clusters is a common unknown feature for the clustering methods, such as hierarchical
cluster analysis, k-means and fuzzy c-means. In this study, we apply a FCM based clustering algorithm to obtain the best number
of clusters as given by the minimum validity index value. This often results in an excessive number of clusters being created
due to the complexity of this biochemical system. A novel method to automatically merge clusters was developed to try to address
this problem. Three lymph node tissue sections were examined to evaluate our new method. These results showed that this approach
can merge the clusters which have similar biochemistry. Consequently, the overall algorithm automatically identifies clusters
that accurately match the main tissue types that are independently determined by the clinician. 相似文献
15.
Voucher-based reinforcement therapy (VBRT) is an effective drug abuse treatment, but the cost of VBRT rewards has limited its dissemination. Obtaining VBRT incentives through donations may be one way to overcome this barrier. Two direct mail campaigns solicited donations for use in VBRT for pregnant, postpartum, and parenting drug users in Toronto, Ontario, Canada, and in Los Angeles, California. In Toronto, 19% of those contacted over 2 months donated $8,000 ($4,000/month) of goods and services. In Los Angeles, nearly 26% of those contacted over 34 months donated $161,000 ($4,472/month) of goods and services. Maintaining voucher programs by soliciting donations is feasible and sustainable. The methods in this article can serve as a guide for successful donation solicitation campaigns. Donations offer an alternative for obtaining VBRT rewards for substance abuse treatment and may increase its dissemination. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
16.
An important aspect of the vehicle routing problem (VRP) that has been largely overlooked is the use of satellite facilities to replenish vehicles during a route. When possible, satellite replenishment allows the drivers to continue making deliveries until the close of their shift without necessarily returning to the central depot. This situation arises primarily in the distribution of fuels and certain retail items. When demand is random, optimizing customer routes a priori may result in significant additional costs for a particular realization of demand. Satellite facilities are one way of safeguarding against unexpected demand. This paper presents a branch and cut methodology for solving the VRP with satellite facilities subject to capacity and route time constraints. We begin with a mixed-integer linear programming formulation and then describe a series of valid inequalities that can be used to cut off solutions to the linear programming relaxation. Several separation heuristics are then outlined that are used to generate the cuts. Embedded in the methodology is a VRP heuristic for finding good feasible solutions at each stage of the computations. Results are presented for a set of problems derived from our experience with a leading propane distributor. 相似文献
17.
Peter J. Bentley Jonathan P. Wakefield 《Computer-Aided Civil and Infrastructure Engineering》1996,11(3):153-161
Abstract: This paper examines the first stage of using genetic algorithms in design—how to encode designs as chromosomes. Generic representations capable of describing the geometry of any solid object to eliminate the unnecessary duplication of work at this stage are explored. A suitable low-parameter, spatial-partitioning representation is then proposed, using partitions consisting of six-sided polyhedra intersected by planes. Finally, the coding of the representation is examined, with the conclusion that allelic coding with control genes and user-definable, fixed-value alleles would provide the most flexible system. 相似文献
18.
19.
A classification of models of visual word recognition is presented that facilitates formal comparisons between models of different formats. In light of the theoretical contributions to this special section, sets of criteria for the evaluation of models and strategies for model construction are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
20.
Michael Vermut William R. Widner Jonathan D. Dinman Reed B. Wickner 《Yeast (Chichester, England)》1994,10(11):1477-1479
MKT1 is required for m aintenance of K2 above 30°C in strains with the L-A-HN variant of the L-A double-stranded RNA virus of Saccharomyces cerevisiae. We report that MKT1 encodes a 92 979 Da protein with serine-rich regions and the retroviral protease signature, DTG, but with no substantial homology to proteins presently in the databases. This sequence is available from GenBank under Accession Number U09129. 相似文献