全文获取类型
收费全文 | 15657篇 |
免费 | 2678篇 |
国内免费 | 1948篇 |
专业分类
电工技术 | 850篇 |
综合类 | 1670篇 |
化学工业 | 416篇 |
金属工艺 | 497篇 |
机械仪表 | 1074篇 |
建筑科学 | 596篇 |
矿业工程 | 425篇 |
能源动力 | 279篇 |
轻工业 | 290篇 |
水利工程 | 165篇 |
石油天然气 | 514篇 |
武器工业 | 264篇 |
无线电 | 3234篇 |
一般工业技术 | 1117篇 |
冶金工业 | 347篇 |
原子能技术 | 80篇 |
自动化技术 | 8465篇 |
出版年
2024年 | 89篇 |
2023年 | 255篇 |
2022年 | 555篇 |
2021年 | 573篇 |
2020年 | 575篇 |
2019年 | 529篇 |
2018年 | 496篇 |
2017年 | 624篇 |
2016年 | 684篇 |
2015年 | 855篇 |
2014年 | 1135篇 |
2013年 | 1061篇 |
2012年 | 1268篇 |
2011年 | 1308篇 |
2010年 | 1182篇 |
2009年 | 1174篇 |
2008年 | 1191篇 |
2007年 | 1197篇 |
2006年 | 1015篇 |
2005年 | 851篇 |
2004年 | 667篇 |
2003年 | 616篇 |
2002年 | 425篇 |
2001年 | 354篇 |
2000年 | 312篇 |
1999年 | 244篇 |
1998年 | 208篇 |
1997年 | 177篇 |
1996年 | 104篇 |
1995年 | 107篇 |
1994年 | 87篇 |
1993年 | 58篇 |
1992年 | 48篇 |
1991年 | 37篇 |
1990年 | 44篇 |
1989年 | 28篇 |
1988年 | 25篇 |
1987年 | 7篇 |
1986年 | 13篇 |
1985年 | 14篇 |
1984年 | 16篇 |
1983年 | 19篇 |
1982年 | 11篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 8篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
A feasibility analysis methodology adopted from reactive distillation is applied to membrane reactors. A model is formulated to depict the reactive liquid phase composition on the retentate side of a continuous type membrane reactor. The effects of both the chemical reaction kinetics and the membrane mass transfer kinetics on the feasible products are elucidated by means of retentate phase diagrams and bifurcation analysis. The proposed method can be applied to various membrane processes, independent of the specific structure of the membrane. Two quaternary reaction systems are considered to illustrate the methodology. In the first hypothetical system, it is shown how selective membranes can influence the sequence of effective volatilities which in turn affects the feasible products of the system. In the second example of practical importance, i.e. the heterogeneously catalysed synthesis of propyl acetate coupled with permeation through a porous polycarbonate membrane, the dusty gas model is applied to describe the component fluxes through the membrane. For the latter reaction system, the existence of reactive arheotrope is demonstrated. Arheotropes represent mass transfer controlled feasible products of membrane separation process. 相似文献
32.
Lean philosophy: implementation in a forging company 总被引:2,自引:2,他引:0
Ajit Kumar Sahoo N. K. Singh Ravi Shankar M. K. Tiwari 《The International Journal of Advanced Manufacturing Technology》2008,36(5-6):451-462
This research addresses the implementation of lean philosophy in a forging company with a focus on radial forging production
flow lines. Here, the prime motive is to evolve and test several strategies to eliminate waste on the shop floor. In this
research, a systematic approach is suggested for the implementation of lean principles. This paper describes an application
of value stream mapping (VSM). Consequently, the present and future states of value stream maps are constructed to improve
the production process by identifying waste and its sources. Furthermore, Taguchi’s method of design of experiments is pursued
here to minimize the forging defects produced due to imperfect operating conditions. A noticeable reduction in set-up time
and work-in-process (WIP) inventory level is substantiated. Finally, we conclude with a discussion of managerial implications
and the future scope of research. 相似文献
33.
34.
Doratha E Drake 《Information Processing Letters》2003,85(4):211-213
We present a linear time approximation algorithm with a performance ratio of 1/2 for finding a maximum weight matching in an arbitrary graph. Such a result is already known and is due to Preis [STACS'99, Lecture Notes in Comput. Sci., Vol. 1563, 1999, pp. 259-269]. Our algorithm uses a new approach which is much simpler than the one given by Preis and needs no amortized analysis for its running time. 相似文献
35.
一种基于知识地图集的知识管理系统模型框架 总被引:9,自引:0,他引:9
在分析知识管理、知识管理系统(KMS)的含义和知识地图集技术的特点的基础上,提出了一种基于知识地图集的KMS模型框架,并且分析了该模型框架中知识地图集的组成及功能,讨论了KMS中知识地图集和知识存储之间的关系。依据该模型框架,组织易于构建知识管理系统,实现知识资源的共享与充分运用。最后,通过一个实例分析进一步说明了该模型框架的应用。 相似文献
36.
Kimmo Fredriksson 《Information Processing Letters》2003,87(4):201-204
Given a text T[1…n] and a pattern P[1…m] over some alphabet Σ of size σ, we want to find all the (exact) occurrences of P in T. The well-known shift-or algorithm solves this problem in time O(n⌈m/w⌉), where w is the number of bits in machine word, using bit-parallelism. We show how to extend the bit-parallelism in another direction, using super-alphabets. This gives a speed-up by a factor s, where s is the number of characters processed simultaneously. The algorithm is implemented, and we show that it works well in practice too. The result is the fastest known algorithm for exact string matching for short patterns and small alphabets. 相似文献
37.
The self-organizing map (SOM) [5] provides a general data approximation method which is suitable for several application domains. The topology preservation is an important feature in data-analysis and may also be advantageous for the evaluation of the data in a function approximation or regression task. For this reason the interpolated self-organizing map (I-SOM) adds an output layer to the SOM architecture which computes a real valued output vector. This paper presents an extension of I-SOM towards a continuous interpolation. It is compared to RBF and to the parametrized self-organizing map. 相似文献
38.
声表面波滤波器的匹配电路设计 总被引:1,自引:0,他引:1
介绍了通过测试仪器采集的声表面波(SAW)滤波器的Sij(i,j=1,2)参数来优化匹配电路的方法。首先将采集的Sij(i,j=1,2)参数转换为SAW滤波器Yij(i,j=1,2)参数,然后建立新的S12(或S21)参数与匹配电路的依赖关系,通过优化匹配电路元件值,而使滤波器的插入损耗和通带波动满足目标值,该方法的主要优点是考虑整个通带特性,而不是考虑通带内的某一点(如中心频率)。 相似文献
39.
40.