全文获取类型
收费全文 | 33131篇 |
免费 | 5360篇 |
国内免费 | 3612篇 |
专业分类
电工技术 | 4734篇 |
技术理论 | 3篇 |
综合类 | 3802篇 |
化学工业 | 1280篇 |
金属工艺 | 515篇 |
机械仪表 | 1761篇 |
建筑科学 | 2897篇 |
矿业工程 | 864篇 |
能源动力 | 1278篇 |
轻工业 | 1686篇 |
水利工程 | 1741篇 |
石油天然气 | 832篇 |
武器工业 | 702篇 |
无线电 | 4756篇 |
一般工业技术 | 2541篇 |
冶金工业 | 1285篇 |
原子能技术 | 359篇 |
自动化技术 | 11067篇 |
出版年
2024年 | 144篇 |
2023年 | 749篇 |
2022年 | 1151篇 |
2021年 | 1348篇 |
2020年 | 1492篇 |
2019年 | 1337篇 |
2018年 | 1307篇 |
2017年 | 1433篇 |
2016年 | 1722篇 |
2015年 | 1722篇 |
2014年 | 2419篇 |
2013年 | 2883篇 |
2012年 | 2607篇 |
2011年 | 2949篇 |
2010年 | 2202篇 |
2009年 | 2133篇 |
2008年 | 2070篇 |
2007年 | 2170篇 |
2006年 | 1922篇 |
2005年 | 1545篇 |
2004年 | 1235篇 |
2003年 | 1017篇 |
2002年 | 798篇 |
2001年 | 667篇 |
2000年 | 534篇 |
1999年 | 424篇 |
1998年 | 379篇 |
1997年 | 304篇 |
1996年 | 254篇 |
1995年 | 205篇 |
1994年 | 171篇 |
1993年 | 154篇 |
1992年 | 123篇 |
1991年 | 89篇 |
1990年 | 84篇 |
1989年 | 67篇 |
1988年 | 57篇 |
1987年 | 31篇 |
1986年 | 25篇 |
1985年 | 14篇 |
1984年 | 32篇 |
1983年 | 20篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1980年 | 14篇 |
1979年 | 8篇 |
1977年 | 5篇 |
1965年 | 14篇 |
1960年 | 4篇 |
1959年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
101.
Presents an obituary for Douglas W. Bray, the inventor of the modern-day assessment center, a method used by thousands of organizations around the world to identify the best people for critical roles and to guide individuals in optimizing their talents. Bray's death in Englewood, New Jersey, on May 9, 2006, ended the extraordinary career of a pioneer in industrial/organizational (I/O) psychology who optimized the interplay of research and application. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
102.
LIU Xiao-wen LI Na PAN Chun-de 《中国矿业大学学报(英文版)》2005,15(4):344-347
An embedded protective device for 35kV power line is worked out based on Philips' LPC2292 ARM MCU. Several aspects such as embedded design technique adopted in the system framework, application of adaptive theory in data acquisition, Board Support Packet (BSP) developing and task dispatching related to operating system are discussed. Both hardware and software framework of the system are given. Advanced hardware platform and software development environment is applied in design of the system, with the advanced co-design technology. 相似文献
103.
104.
G. Bartolini A. Ferrara 《International Journal of Adaptive Control and Signal Processing》1992,6(3):237-246
In this paper we pursue a twofold aim. First we want to simplify the complexity of the classical Monopoli's scheme, the so-called ‘Augmented error signal control scheme’. Then we also wish to cope with the realistic situation in which the presence of unmodelled dynamics has to be taken into account. This latter problem has been faced in the literature by suitably modifying the adaptation mechanism in order to avoid undesired phenomena as well as to obtain an attractive stability region for the state trajectories starting from any point in a predefined initial condition set. In our case the necessity of introducing any sort of modification in the adaptation mechanism is completely avoided, but we still obtain asymptotic stability of the output error signal. 相似文献
105.
The aim of this paper is to assess the state-of-the-art in the Decision Support Systems (DSS) field from both a research and a practice perspective. Three main dimensions of DSS research and practice are addressed: 1) supporting human decision-making processes, 2) integrating DSS into the organizational context, and 3) identifying new application domains. The related analysis and discussion provides a better understanding of past developments in the DSS field and insights into future evolution patterns. 相似文献
106.
钢中非金属夹杂物显微评级方法的定量化探讨 总被引:2,自引:0,他引:2
应用IBAS系列图像分析系统,对建立一套与国家标准GB10561─89兼容的钢中非金属夹杂物显微评级方法的自动化和定量化标准作了可行性分析,结果表明建立这套标准是切实可行的。 相似文献
107.
108.
球罐活性缺陷的模糊评定方法 总被引:6,自引:0,他引:6
根据国内外有关标准和文献,利用模糊数学中的模糊描述和隶属度等概念,首次采用多级模糊综合评定理论,分层次地把活性缺陷的主要监测信息(即声发射源信息)和专家们的经验考虑在内,建立在用球形贮罐声发射源严重度多级模糊综合评定模型和方法,并编制计算机数据分析和处理程序,使评定结果趋于更合理和可靠.并给出在用球形贮罐声发射源严重度多级模糊综合评定算例,结果表明,该评定方法可以达到定量化的程度,与局部无损复验结果有良好的一致性. 相似文献
109.
Abstract. This paper examines the capacity of the research designs of 37 empirical studies of information systems (IS) effectiveness to provide a basis for the development of theories about behaviour related to IS effectiveness. The power of each study to support causal inference was evaluated in terms of (a) its handling of the time dimension, (b) its ability to weigh differences and (c) its resistance to internal validity threats that pose alternative explanations for its reported findings. Of the reviewed studies, 29.7% could account for the time dimension, 32.4% employed a comparison group and 16.2% were not susceptible to any internal validity threats. Only 13.5% of the studies combined an accounting for the time dimension with the use of a comparison group. Of these, however, only 5.4% were also invulnerable to internal validity threats. The research designs of nearly 95% of these published studies were deficient in supporting causal inference. In those studies, suggestions that one variable was causally related to another variable could not be substantiated. Encouragement for the future capacity of IS effectiveness research to support causal inference was found in a trend towards the use of quasiexperimental designs. Recommendations are made regarding ways to increase the inferential capacity of research designs employed in the study of IS effectiveness. 相似文献
110.
This paper finds the appropriate pi-coefficients for a parameter estimation adaptive system and uses them to analyze the stability of two estimation algorithms. The estimation error dynamics of the system are modeled by a linear time-invariant subsystem and a nonlinear time-varying update law in a feedback loop. Then the so-called max-p problems are formulated and solved to obtain the pi-coefficients for the linear subsystem and nonlinear update low. For the investigated system, the quantitative results show that the least-squares update algorithm has larger stability range than that of the gradient algorithm, and the σ-modification scheme gives larger stability ranges for both algorithms. 相似文献