全文获取类型
收费全文 | 26731篇 |
免费 | 3274篇 |
国内免费 | 2599篇 |
专业分类
电工技术 | 2567篇 |
技术理论 | 2篇 |
综合类 | 3130篇 |
化学工业 | 1926篇 |
金属工艺 | 2438篇 |
机械仪表 | 1620篇 |
建筑科学 | 1791篇 |
矿业工程 | 1445篇 |
能源动力 | 591篇 |
轻工业 | 595篇 |
水利工程 | 548篇 |
石油天然气 | 679篇 |
武器工业 | 389篇 |
无线电 | 3118篇 |
一般工业技术 | 2755篇 |
冶金工业 | 1448篇 |
原子能技术 | 144篇 |
自动化技术 | 7418篇 |
出版年
2024年 | 66篇 |
2023年 | 344篇 |
2022年 | 661篇 |
2021年 | 889篇 |
2020年 | 922篇 |
2019年 | 728篇 |
2018年 | 709篇 |
2017年 | 871篇 |
2016年 | 936篇 |
2015年 | 1214篇 |
2014年 | 1884篇 |
2013年 | 1759篇 |
2012年 | 2152篇 |
2011年 | 2238篇 |
2010年 | 1703篇 |
2009年 | 1691篇 |
2008年 | 1615篇 |
2007年 | 1964篇 |
2006年 | 1656篇 |
2005年 | 1365篇 |
2004年 | 1085篇 |
2003年 | 1011篇 |
2002年 | 833篇 |
2001年 | 684篇 |
2000年 | 607篇 |
1999年 | 485篇 |
1998年 | 401篇 |
1997年 | 390篇 |
1996年 | 289篇 |
1995年 | 268篇 |
1994年 | 269篇 |
1993年 | 170篇 |
1992年 | 149篇 |
1991年 | 130篇 |
1990年 | 115篇 |
1989年 | 107篇 |
1988年 | 67篇 |
1987年 | 28篇 |
1986年 | 18篇 |
1985年 | 24篇 |
1984年 | 22篇 |
1983年 | 16篇 |
1982年 | 14篇 |
1981年 | 11篇 |
1980年 | 11篇 |
1979年 | 6篇 |
1965年 | 4篇 |
1963年 | 3篇 |
1961年 | 3篇 |
1959年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
从冷却曲线上相变段倾角最小原则出发,研究了新型激冷剂的配比与热分析法检测铸铁成分精度的关系,实验结果表明,能使相变段倾角最小的成分配比,也能提高对铸铁成分的热分析和检测精度。 相似文献
73.
本文探讨HIS变换对数字化航空片影象与landsat TM多光谱影象进行复合的方法,并在此基础上提出一种改进的方法。试验结果表明本文提出的方法是一种非常行之有效的方法。复合后的影象不仅保留了TM影像的光谱特征,而且将其空间分解力由30m提高到10m,清晰度也提高了。因而复合后的影像能提高分类精度,制作专题图的精度、多时相监测能力和解译水平等。 相似文献
74.
75.
提出利用测量设备与辐射源相对运动速度及测量设备所接收到的辐射功率的估算测量设备到辐射源距离的一种方法。对计算精度进行了分析,通过算例对理论分析进行了检验。 相似文献
76.
J. Dingel 《Formal Aspects of Computing》2002,14(2):123-197
Parallel computers have not yet had the expected impact on mainstream computing. Parallelism adds a level of complexity to
the programming task that makes it very error-prone. Moreover, a large variety of very different parallel architectures exists.
Porting an implementation from one machine to another may require substantial changes. This paper addresses some of these
problems by developing a formal basis for the design of parallel programs in the form of a refinement calculus. The calculus
allows the stepwise formal derivation of an abstract, low-level implementation from a trusted, high-level specification. The
calculus thus helps structuring and documenting the development process. Portability is increased, because the introduction
of a machine-dependent feature can be located in the refinement tree. Development efforts above this point in the tree are
independent of that feature and are thus reusable. Moreover, the discovery of new, possibly more efficient solutions is facilitated.
Last but not least, programs are correct by construction, which obviates the need for difficult debugging. Our programming/specification
notation supports fair parallelism, shared-variable and message-passing concurrency, local variables and channels. The calculus
rests on a compositional trace semantics that treats shared-variable and message-passing concurrency uniformly. The refinement
relation combines a context-sensitive notion of trace inclusion and assumption-commitment reasoning to achieve compositionality.
The calculus straddles both concurrency paradigms, that is, a shared-variable program can be refined into a distributed, message-passing
program and vice versa.
Received July 2001 / Accepted in revised form May 2002 相似文献
77.
78.
本文应用配极变换的几何性质来确定锥面截交线的中心及其主要轴线,这对于准确地绘制或使用数控绘图机来绘制二次曲线.是很有意义的. 相似文献
79.
In this paper,a new method is presented for 3D motion estimation by image region correspondences using stereo cameras.Under the weak perspectivity assumption.we first employ the moment tensor theory (Cyganski and Orr^[11]) to compute the monocular affine transformations relating images taken by the same camera at different time instants and the binocular affine transformations relating images taken by different cameras at the same time instant.We then show that 3D motion can be recovered from these 2D transformations.A space-time fusion strategy is proposed to aim at robust results.No knowledge of point correspondences if requred in the above processes and the computations involved are linear.To find corresponding image regions,new affine invariants,which show stronger invariance,are derived in term of tensor contraction theory.Experiments on real motion images are conducted to verify the proposed method. 相似文献
80.
Locally Weighted Learning 总被引:22,自引:0,他引:22
Christopher G. Atkeson Andrew W. Moore Stefan Schaal 《Artificial Intelligence Review》1997,11(1-5):11-73
This paper surveys locally weighted learning, a form of lazy learning and memory-based learning, and focuses on locally weighted linear regression. The survey discusses distance functions, smoothing parameters, weighting functions, local model structures, regularization of the estimates and bias, assessing predictions, handling noisy data and outliers, improving the quality of predictions by tuning fit parameters, interference between old and new data, implementing locally weighted learning efficiently, and applications of locally weighted learning. A companion paper surveys how locally weighted learning can be used in robot learning and control. 相似文献