全文获取类型
收费全文 | 53530篇 |
免费 | 9088篇 |
国内免费 | 5546篇 |
专业分类
电工技术 | 4975篇 |
技术理论 | 2篇 |
综合类 | 4653篇 |
化学工业 | 2381篇 |
金属工艺 | 2143篇 |
机械仪表 | 3934篇 |
建筑科学 | 2307篇 |
矿业工程 | 1009篇 |
能源动力 | 474篇 |
轻工业 | 4317篇 |
水利工程 | 549篇 |
石油天然气 | 1182篇 |
武器工业 | 826篇 |
无线电 | 11671篇 |
一般工业技术 | 3882篇 |
冶金工业 | 1237篇 |
原子能技术 | 554篇 |
自动化技术 | 22068篇 |
出版年
2024年 | 481篇 |
2023年 | 1524篇 |
2022年 | 2552篇 |
2021年 | 2789篇 |
2020年 | 2673篇 |
2019年 | 2058篇 |
2018年 | 1711篇 |
2017年 | 2252篇 |
2016年 | 2425篇 |
2015年 | 2746篇 |
2014年 | 4282篇 |
2013年 | 3673篇 |
2012年 | 4552篇 |
2011年 | 4755篇 |
2010年 | 3581篇 |
2009年 | 3533篇 |
2008年 | 3529篇 |
2007年 | 3883篇 |
2006年 | 3152篇 |
2005年 | 2626篇 |
2004年 | 1979篇 |
2003年 | 1642篇 |
2002年 | 1220篇 |
2001年 | 865篇 |
2000年 | 731篇 |
1999年 | 549篇 |
1998年 | 460篇 |
1997年 | 351篇 |
1996年 | 316篇 |
1995年 | 229篇 |
1994年 | 163篇 |
1993年 | 149篇 |
1992年 | 147篇 |
1991年 | 117篇 |
1990年 | 90篇 |
1989年 | 57篇 |
1988年 | 53篇 |
1987年 | 31篇 |
1986年 | 35篇 |
1985年 | 27篇 |
1984年 | 32篇 |
1983年 | 24篇 |
1982年 | 19篇 |
1981年 | 21篇 |
1980年 | 23篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1976年 | 5篇 |
1975年 | 6篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
151.
John Tsinias 《Systems & Control Letters》1991,17(1)
In this paper we generalize the Vidyasagar's well known theorem on the local stabilizability problem of nonlinear systems using state detection [11]. Our purpose is to prove that if a system is weakly detectable and stabilizable by means of a continuous state feedback u = γ(x), for which no differentiability assumption is imposed, then the system is also stabilized by the law u = γ(z), where z is the output of a weak detector for the state x. The result above is applicable to several cases not covered by other works. 相似文献
152.
L. Pibida M. Unterweger L. R. Karam 《Journal of research of the National Institute of Standards and Technology》2004,109(4):451-456
Characterization of commercially available instruments for measurement and identification of unknown radionuclides was carried out in support of the development and testing of the American National Standards Institute (ANSI) standard, N42.34, “Performance Criteria for Hand-held Instruments for the Detection and Identification of Radionuclides.” Measurements were based on the performance of the devices, i.e., the capability of the detectors to ensure a correct radionuclide identification in a given time interval for various radioactive sources. 相似文献
153.
Parity space approach and H2 approach are two important fault detection approaches. This paper studies the relationship between these two approaches, which reveals frequency domain characteristics of the optimal solution of the parity space approach on the one side and provides a numerical solution of the H2-optimal design of residual generators on the other side. 相似文献
154.
155.
M. Komatsu Y. Matsukawa K. Yasunaga M. Kiritani 《Materials Science and Engineering: A》2003,350(1-2):25-29
Heavy plastic deformation of fcc metal thin foils to fracture has been found recently to proceed without involving dislocations, and it results in the formation of high density of vacancy clusters. Thin foil specimens of bcc metals such as V and Mo were plastically deformed to fracture in in situ elongation experiments under an electron microscope. Morphology of thinning and fracture was found to be similar to fcc metals, and no dislocation was observed during heavy deformation. Electron diffraction analysis at the tip of a crack during deformation confirmed a large elastic deformation of up to 5%. Unlike in fcc metal thin foil specimens, point defect clusters were not observed near fractured tips. This difference is attributed to the difference in vacancy reaction, though the deformation in bcc metals without dislocation most likely does produce vacancies. 相似文献
156.
157.
This paper deals with fault detection problems in sampled-data (SD) systems. A tool is first introduced for the analysis of intersample behavior of SD systems in the frequency domain from the viewpoint of fault detection and isolation. Based on it, a direct design approach of fault detection systems for SD systems is proposed, and further the problem of full decoupling from unknown disturbances is studied. 相似文献
158.
A new image analysis technique has been developed which allows maceral analysis of coal to be carried out. The technique is able to separate the liptinite component from the background resin by using two separate images of the surface captured with different camera exposure times. At normal exposure, the liptinite has a similar grey scale value to the surrounding resin, but at a higher exposure time, the resin remains black whilst the liptinite grey scale increases significantly enough to distinguish it from the resin. The method has been tested for repeatability and reproducibility and found to be within the ISO Standard requirements. 相似文献
159.
160.
生物超微弱发光的光子计数成象方法 总被引:1,自引:0,他引:1
介绍了我们研制和设计的用于测量生物超微弱发光的光子计数成象系统,包括光子成象头,高帧频CCD摄象机,图象采集系统和计算机,可以定量地探测出生物的发光强度分布 ,还能够显示出其发光的图象,确定发光的形状和位置,本系统的信噪比为10:1,最小探测功率达10^-16W,灵敏度高,动态范围大。 相似文献