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   82792篇
  免费   6721篇
  国内免费   3628篇
电工技术   3733篇
技术理论   5篇
综合类   6275篇
化学工业   16269篇
金属工艺   7239篇
机械仪表   5372篇
建筑科学   6461篇
矿业工程   3174篇
能源动力   2082篇
轻工业   7148篇
水利工程   2120篇
石油天然气   3533篇
武器工业   705篇
无线电   4320篇
一般工业技术   7186篇
冶金工业   6402篇
原子能技术   519篇
自动化技术   10598篇
  2024年   344篇
  2023年   932篇
  2022年   1771篇
  2021年   2192篇
  2020年   2546篇
  2019年   1911篇
  2018年   1723篇
  2017年   2191篇
  2016年   2589篇
  2015年   2804篇
  2014年   5156篇
  2013年   5195篇
  2012年   6196篇
  2011年   6447篇
  2010年   4676篇
  2009年   4822篇
  2008年   4224篇
  2007年   5412篇
  2006年   5064篇
  2005年   4389篇
  2004年   3772篇
  2003年   3358篇
  2002年   2887篇
  2001年   2446篇
  2000年   2015篇
  1999年   1652篇
  1998年   1267篇
  1997年   994篇
  1996年   916篇
  1995年   715篇
  1994年   596篇
  1993年   395篇
  1992年   348篇
  1991年   270篇
  1990年   187篇
  1989年   159篇
  1988年   121篇
  1987年   74篇
  1986年   60篇
  1985年   44篇
  1984年   45篇
  1983年   33篇
  1982年   20篇
  1981年   22篇
  1980年   29篇
  1979年   16篇
  1977年   14篇
  1964年   8篇
  1959年   9篇
  1951年   18篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
建立和维护产品全生命周期中各种应用活动之间动态的信息关联,是实现产品数据集成、保证各应用领域协调活动的关键,为此,提出了基于产品设计过程的产品协调模型,该模型将原用于基于历史的几个何特征建模的特征编码作为建立和维护产品几何信息及其它应用信息间关联的纽带,为了屏蔽特征编码机制的私有属性,建立了比特征编码机制更高层的协议-数据协调协议,该协议为在产品几何信息与非几何应用信息之间建立和维护动态的、协调一  相似文献   
992.
文件实时监控处理过程在控制程序处理过程中被广泛运用。本文结合文件处理的实际工作,描述了文件处理程序的监控处理过程,实现了基于进程管理的文件监控处理与预处理过程的协同工作。  相似文献   
993.
对于一个实际的时间序列数据,我们并不知道其真正的数据生成过程,只能通过假设和基于假设的统计推断来确定。本文利用蒙特卡罗模拟进行有限样本的ADF检验。结果表明,当原假设是存在单位根,备择假设是趋势稳定时,ADF检验的势很低。这意味着,我国GNP存在单位根是不确定的。  相似文献   
994.
在一个模拟或者混合信号系统中,恒定电流源为电路提供偏置,它的稳定性直接决定了电路的性能。该文通过设计合适的电路,利用不同工艺条件下跨导参数K’和阈值电压Vt之间的变化关系来消除工艺变化对电流的影响。另外,通过一个随温度变化的电压源对电源电压和温度进行补偿。整个电路采用CSMC 0.5um双层多晶硅,双层金属标准工艺来设计.采用candence spectre进行模拟仿真,仿真结果证明电路对工艺,温度及电压的变化都具有良好的补偿能力。  相似文献   
995.
A new interpretation of software engineering from scientific, engineering, and practical standpoints is proposed. Software engineering is defined as a successor of programming and computer science, namely, its management theory. Features and attributes of software engineering as an original discipline are founded. The structure, content, and concepts of this discipline and its basic elements are presented. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 3, pp. 19–28, May–June 2008.  相似文献   
996.
What is the impact of business process standardization on business process outsourcing (BPO) success? This paper argues that there is a direct impact of process standardization on BPO success, due to production cost economies, and also an indirect effect via improved contractual and relational governance resulting from better monitoring opportunities and facilitated communication and coordination. This threefold impact of standardization on BPO success is empirically confirmed using data from 335 BPO ventures in 215 German banks.  相似文献   
997.
In this study, a robust nonlinear Lgain tracking control design for uncertain robotic systems is proposed under persistent bounded disturbances. The design objective is that the peak of the tracking error in time domain must be as small as possible under persistent bounded disturbances. Since the nonlinear Lgain optimal tracking control cannot be solved directly, the nonlinear Lgain optimal tracking problem is transformed into a nonlinear Lgain tracking problem by given a prescribed disturbance attenuation level for the Lgain tracking performance. To guarantee that the Lgain tracking performance can be achieved for the uncertain robotic systems, a sliding‐mode scheme is introduced to eliminate the effect of the parameter uncertainties. By virtue of the skew‐symmetric property of the robotic systems, sufficient conditions are developed for solving the robust Lgain tracking control problems in terms of an algebraic equation instead of a differential equation. The proposed method is simple and the algebraic equation can be solved analytically. Therefore, the proposed robust Lgain tracking control scheme is suitable for practical control design of uncertain robotic systems. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society  相似文献   
998.
In Kahn process network (KPN), the processes (nodes) communicate by unbounded unidirectional FIFO channels (arcs), with the property of non-blocking writes and blocking reads on the channels. KPN provides a semantic model of computation, where a computation can be expressed as a set of asynchronously communicating processes. However, the unbounded FIFO based asynchrony is not realizable in practice and hence requires refinement in real hardware. In this work, we start with KPN as the model of computation for GALS, and discuss how different GALS architectures can be realized. We borrow some ideas from existing dataflow architectures for our GALS designs.  相似文献   
999.
The Technology Acceptance Model (TAM) has been considered to be fundamental in determining the acceptance of new technology in the past decades. The two beliefs, ease of use and usefulness, in the model may not, however, fully explain the consumers’ behavior in an emerging environment, such as mobile commerce (m-commerce). This paper aims to develop a framework for m-commerce adoption in consumer decision-making processes. In this paper TAM has been adopted and extended to analyze successful m-commerce adoption. The key elements of the proposed confidence-based framework for B2C m-commerce adoption include psychological and behavioral factors. Psychological factors include history-based confidence, institution-based confidence and personality-based confidence. Behavioral factors include perceived ease of use and perceived usefulness of the mobile application and technology.  相似文献   
1000.
At the development of commercial vehicles, it is necessary to develop cost-optimized components with respect to their entire lifetime. This requires a product development process that utilizes the possibility to simulate the product performance using modeling of different degrees of sophistication at any predefined level-of-detail (LOD). For example, the mechanical properties of a cast component depend strongly on the casting process, the simulation of which requires complex modeling at a high LOD. In this article, we propose an optimization strategy that is based on the LOD concept to develop cost-effective components. A sizing optimization of a cast model component is carried out with respect to both the mechanical and thermal response to exemplify the process. In particular, a (novel) global measure of the temperature in energy norm is introduced as an indicator of the “production fitness” to ensure high quality of the material properties. This measure is the thermal counterpart of the well-accepted mechanical strain energy.  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