全文获取类型
收费全文 | 12284篇 |
免费 | 108篇 |
国内免费 | 191篇 |
专业分类
电工技术 | 176篇 |
综合类 | 80篇 |
化学工业 | 461篇 |
金属工艺 | 621篇 |
机械仪表 | 150篇 |
建筑科学 | 397篇 |
矿业工程 | 42篇 |
能源动力 | 144篇 |
轻工业 | 117篇 |
水利工程 | 63篇 |
石油天然气 | 46篇 |
武器工业 | 1篇 |
无线电 | 517篇 |
一般工业技术 | 350篇 |
冶金工业 | 227篇 |
原子能技术 | 94篇 |
自动化技术 | 9097篇 |
出版年
2023年 | 5篇 |
2022年 | 18篇 |
2021年 | 32篇 |
2020年 | 20篇 |
2019年 | 37篇 |
2018年 | 28篇 |
2017年 | 18篇 |
2016年 | 43篇 |
2015年 | 32篇 |
2014年 | 246篇 |
2013年 | 318篇 |
2012年 | 813篇 |
2011年 | 3157篇 |
2010年 | 1183篇 |
2009年 | 1045篇 |
2008年 | 713篇 |
2007年 | 624篇 |
2006年 | 495篇 |
2005年 | 626篇 |
2004年 | 671篇 |
2003年 | 721篇 |
2002年 | 373篇 |
2001年 | 341篇 |
2000年 | 250篇 |
1999年 | 91篇 |
1998年 | 151篇 |
1997年 | 82篇 |
1996年 | 49篇 |
1995年 | 84篇 |
1994年 | 61篇 |
1993年 | 23篇 |
1992年 | 17篇 |
1991年 | 17篇 |
1990年 | 18篇 |
1989年 | 34篇 |
1988年 | 14篇 |
1987年 | 16篇 |
1986年 | 15篇 |
1985年 | 11篇 |
1984年 | 33篇 |
1983年 | 15篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Journal of Signal Processing Systems - 相似文献
2.
Alexandros Papadopoulos Issaak Parcharidis Panagiotis Elias Pierre Briole 《International journal of remote sensing》2019,40(16):6365-6382
We analysed the ground deformation across two blocks defined by the Rio-Patras fault from 1993 to 2017 using multi-temporal Synthetic Aperture Radar Interferometry (InSAR) techniques. Our main objective was to contribute to the assessment of seismic hazard near the large city of Patras. Multiple data-sets were used, each one covering different temporal periods. Descending and ascending acquisitions, providing different viewing geometries contribute to fully determine the ground displacement in 3D. The data-sets used are from the European Space Agency’s (ESA) European Remote Sensing (ERS), Environmental Satellite (ENVISAT) and SENTINEL-1 as well as German Aerospace Center (DLR) ’s TERRASAR-X missions. Considering ESA’s missions covering both acquisition geometries and long periods, the southern block, showing lack of a sufficient number of scatterers does not allow the displacement characterization. In contrary, the northern block is characterized by a high number of scatterers having values of maximum likehood ranging from ?3.5 to ?4.3 mm year?1 for ascending geometry and from ?1.6 to ?2.7 mm year?1 for the descending one. The fact that both geometries show negative values of displacements are consistent with downlift movement and at the same time the quantitative differentiation probably indicates an horizontal component as well. 相似文献
3.
Evangelos Pavlakis Michelle Neumann Thorsten Stiewe 《International journal of molecular sciences》2020,21(24)
Tumor progression to a metastatic and ultimately lethal stage relies on a tumor-supporting microenvironment that is generated by reciprocal communication between tumor and stromal host cells. The tumor–stroma crosstalk is instructed by the genetic alterations of the tumor cells—the most frequent being mutations in the gene Tumor protein p53 (TP53) that are clinically correlated with metastasis, drug resistance and poor patient survival. The crucial mediators of tumor–stroma communication are tumor-derived extracellular vesicles (EVs), in particular exosomes, which operate both locally within the primary tumor and in distant organs, at pre-metastatic niches as the future sites of metastasis. Here, we review how wild-type and mutant p53 proteins control the secretion, size, and especially the RNA and protein cargo of tumor-derived EVs. We highlight how EVs extend the cell-autonomous tumor suppressive activity of wild-type p53 into the tumor microenvironment (TME), and how mutant p53 proteins switch EVs into oncogenic messengers that reprogram tumor–host communication within the entire organism so as to promote metastatic tumor cell dissemination. 相似文献
4.
5.
Navab SinghAuthor Vitae Moitreyee Mukherjee-RoyAuthor VitaeSohan Singh MehtaAuthor Vitae 《Microelectronics Journal》2003,34(4):237-245
The patterning of contact holes by selecting out-of-focus image plane (defocus) using attenuated phase shift masks (APSM) has been studied. Defocus is found to enhance the image modulation at low partial coherence for contact holes with negative local average of mask function. Semi-dense holes up to 130 nm in 8% APSM have been printed by 0.5 μm defocus at a partial coherence of 0.31 using KrF scanner with highest numerical aperture of 0.68. However, these holes were closed with in-focus imaging. Defocus is also found to be beneficial for patterning the pitches that have extensive side lobes with in-focus imaging. 相似文献
6.
用仿真工具优化车辆动力系统(一) 总被引:1,自引:0,他引:1
在本文的第一部分,介绍了一种理想的车辆动力系统的计算机辅助开发过程。它显示了现代仿真技术在产品持续发展过程中的作用,该技术采用硬件回路作非在线的仿真,并通过现代化的试验手段对车辆进行匹配。特别重要的是提供了将电控变速器和发动机控制单元综合的可能性。接着是在线仿真在诸如发动机和变速器模式方面的应用和发展,它是上述开发过程的基础。根据上述的方法论,本文论述了仿真技术已取得的成绩和将来的应用可能性。 相似文献
7.
Adaptive motion control using neural network approximations 总被引:1,自引:0,他引:1
In this paper, we present a new adaptive technique for tracking control of mechanical systems in the presence of friction and periodic disturbances. Radial Basis Functions (RBFs) are used to compensate for the effects of nonlinearly occurring parameters in the friction and periodic disturbance model. Theoretical analysis, such as stability and transient performance, is provided. Furthermore, the performance of the adaptive RBF controller and its non-adaptive counterpart are compared. 相似文献
8.
9.
Cherng-Min MaAuthor Vitae 《Pattern recognition》2003,36(8):1775-1782
Generally, a reduction operation (e.g., thinning and shrinking) on 3D binary images can be represented as a set of reduction templates where every object voxel of the image satisfying any template is turned to a background voxel. Generally, it is rather difficult, error-prone and time-consuming for verifying the topological soundness of a 3D parallel reduction operation. This paper proposes sufficient conditions of time complexity O(n) for verifying the topological soundness of 3D parallel 6-subiteration reduction operations of n templates where such a kind of 3D reduction operations is performed alternatively from the six orthogonal directions to turn object voxels to background voxels. By such sufficient conditions, the topology soundness of a 3D 6-subiteration parallel reduction operation can be verified by checking each and every of its templates. 相似文献
10.
In this paper, we present a control methodology for a class of discrete time nonlinear systems that depend on a possibly exogenous scheduling variable. This class of systems consists of an interpolation of nonlinear dynamic equations in strict feedback form, and it may represent systems with a time-varying nonlinear structure. Moreover, this class of systems is able to represent some cases of gain scheduling control, Takagi-Sugeno fuzzy systems, as well as input-output realizations of nonlinear systems which are approximated via localized linearizations. We present two control theorems, one using what we call a “global” approach (akin to traditional backstepping), and a “local” approach, our main result, where backstepping is again used but the control law is an interpolation of local control terms. An aircraft wing rock regulation problem with varying angle of attack is used to illustrate and compare the two approaches. 相似文献