全文获取类型
收费全文 | 10132篇 |
免费 | 841篇 |
国内免费 | 687篇 |
专业分类
电工技术 | 451篇 |
技术理论 | 7篇 |
综合类 | 1530篇 |
化学工业 | 726篇 |
金属工艺 | 285篇 |
机械仪表 | 297篇 |
建筑科学 | 3103篇 |
矿业工程 | 405篇 |
能源动力 | 243篇 |
轻工业 | 482篇 |
水利工程 | 608篇 |
石油天然气 | 620篇 |
武器工业 | 52篇 |
无线电 | 280篇 |
一般工业技术 | 769篇 |
冶金工业 | 603篇 |
原子能技术 | 88篇 |
自动化技术 | 1111篇 |
出版年
2024年 | 42篇 |
2023年 | 139篇 |
2022年 | 244篇 |
2021年 | 294篇 |
2020年 | 281篇 |
2019年 | 268篇 |
2018年 | 240篇 |
2017年 | 270篇 |
2016年 | 314篇 |
2015年 | 354篇 |
2014年 | 559篇 |
2013年 | 525篇 |
2012年 | 653篇 |
2011年 | 812篇 |
2010年 | 617篇 |
2009年 | 782篇 |
2008年 | 699篇 |
2007年 | 569篇 |
2006年 | 564篇 |
2005年 | 572篇 |
2004年 | 416篇 |
2003年 | 387篇 |
2002年 | 322篇 |
2001年 | 261篇 |
2000年 | 253篇 |
1999年 | 242篇 |
1998年 | 157篇 |
1997年 | 141篇 |
1996年 | 138篇 |
1995年 | 95篇 |
1994年 | 93篇 |
1993年 | 76篇 |
1992年 | 57篇 |
1991年 | 48篇 |
1990年 | 36篇 |
1989年 | 41篇 |
1988年 | 20篇 |
1987年 | 13篇 |
1986年 | 12篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1974年 | 2篇 |
1966年 | 2篇 |
1964年 | 2篇 |
1955年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
1985年11月在瑞士北部进行了一次以探讨“冷池”条件下的扩散和湍流特征为目的的国际野外大气试验,本文介绍其中的四面体气球示踪实验的结果。一共进行了三次由雷达跟踪的四面体示踪实验,释放了10个四面体球。按多轨迹法和单轨迹法分别估算并比较了其中两次示踪实验得到的水平扩散参数σ_y,探讨了风摆效应的贡献。采用“体源模式”并结合单轨迹法估算了微弱风场不定风向条件下的扩散参数,分析了静风,弱风条件下的水平风向标准差和湍流强度。 相似文献
2.
Takeshi Shiofuku Norihiro Abe Yoshihiro Tabuchi Hirokazu Taki Shoujie He 《Artificial Life and Robotics》2008,13(1):290-293
This paper presents an approach of measuring in real-time the vector of finger that is pointing to an object. DSP is used
in the operation processing unit in order to do the real-time processing. The steps include the extraction of flesh-colored
regions from an image, the labeling of the flesh-colored regions, and the detection of two characteristic positions on the
finger so that the direction that the finger is pointing at will be calculated. The entire process takes about 29 msec, which
makes it possible to have the frame rate of 34 fps. With this frame rate, this measurement approach is considered real-time
and promising to be merged into other application systems.
This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January
31–February 2, 2008 相似文献
3.
Markus Stolze 《Knowledge》1994,7(4):271-273
System development is strongly influenced by the perspectives used by system developers. Current development methods for knowledge-based systems are based on an information processing perspectives of experts and users which has been criticized by a number of researchers. The paper argues that work-oriented development of knowledge-based systems requires the parallel use of multiple perspectives (including the information processing perspective), and that the use of any single perspective is potentially dangerous. As an example of the importance of using multiple perspectives, thepaper presents the situated action perspective, and shows how it complements the information processing perspective. 相似文献
4.
Taijiro Nonaka Rodney J. Clifton Taichiro Okazaki 《International Journal of Impact Engineering》1996,18(7-8):889-898
An analysis is presented of longitudinal waves in a thin elastic column. Velocity is specified at one end, and the boundary condition at the other end is expressed in terms of a range of effective impedances of an attached structure. Propagation, reflection and interference of the waves are followed by the method of characteristics. Integration of differential equations along characteristics yields the wave-induced stress, which is then applied to problems of earthquake excitation. Numerical examples are given for recorded updown ground motion of the Kobe Earthquake. 相似文献
5.
6.
Previous research yielded inconsistent results regarding the memory organization of self-performed actions. The authors propose that task performance changes the very basis of memory organization. Enactment during study and test (Experiment 1) yielded stronger enactive clustering (based on motor-movement similarities), whereas verbal encoding yielded stronger conceptual clustering (based on semantic-episodic similarities). Enactment enhanced memory quantity and memory accuracy. Both measures increased with enactive clustering under self-performance instructions but with conceptual clustering under verbal instructions. Enactment only during study (Experiment 2) or only during testing (Experiment 3) also enhanced enactive clustering. It is proposed that different conditions affect the relative salience of different types of memory organization and their relative contribution to recall. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
在压水堆核电站应急计划和应急响应中,堆底熔穿事故占有重要位置。本文用法国核电厂事故源项S3(对应于堆底熔穿事故)计算了在典型气象条件下的场外放射学的后果,根据一般防护决策原则和我国颁布的干预水平,提出了保护公众的应急防护措施的建议。 相似文献
8.
We present a methodology for compiler synthesis based on Mosses-Watt's action semantics. Each action in action semantics notation is assigned specific “analysis functions”, such as a typing function and a binding-time function. When a language is given an action semantics, the typing and binding-time functions for the individual actions compose into typing and binding-time analyses for the language; these are implemented as the type checker and static semantics processor, respectively, in the synthesized compiler. Other analyses can be similarly formalized and implemented. We show a sample language semantics and its synthesized compiler, and we describe the compiler synthesizer that we have developed. 相似文献
9.
10.
杀虫植物的研究新进展及应用发展前景 总被引:13,自引:3,他引:13
介绍了近几年杀虫植物研究的新进展,主要包括楝科、卫矛科、豆科、菊科、胡椒科、百部科、瑞香科等科杀虫植物的作用方式和部分植物的有效成分与作用机制及杀虫植物的应用概况,并分析了其应用发展前景。 相似文献