全文获取类型
收费全文 | 6032篇 |
免费 | 658篇 |
国内免费 | 443篇 |
专业分类
电工技术 | 386篇 |
技术理论 | 3篇 |
综合类 | 891篇 |
化学工业 | 394篇 |
金属工艺 | 138篇 |
机械仪表 | 400篇 |
建筑科学 | 615篇 |
矿业工程 | 189篇 |
能源动力 | 169篇 |
轻工业 | 234篇 |
水利工程 | 150篇 |
石油天然气 | 215篇 |
武器工业 | 96篇 |
无线电 | 571篇 |
一般工业技术 | 732篇 |
冶金工业 | 337篇 |
原子能技术 | 85篇 |
自动化技术 | 1528篇 |
出版年
2024年 | 28篇 |
2023年 | 98篇 |
2022年 | 124篇 |
2021年 | 127篇 |
2020年 | 173篇 |
2019年 | 173篇 |
2018年 | 163篇 |
2017年 | 180篇 |
2016年 | 204篇 |
2015年 | 230篇 |
2014年 | 334篇 |
2013年 | 351篇 |
2012年 | 471篇 |
2011年 | 468篇 |
2010年 | 354篇 |
2009年 | 360篇 |
2008年 | 390篇 |
2007年 | 476篇 |
2006年 | 369篇 |
2005年 | 334篇 |
2004年 | 305篇 |
2003年 | 241篇 |
2002年 | 218篇 |
2001年 | 181篇 |
2000年 | 175篇 |
1999年 | 100篇 |
1998年 | 90篇 |
1997年 | 75篇 |
1996年 | 68篇 |
1995年 | 51篇 |
1994年 | 33篇 |
1993年 | 24篇 |
1992年 | 18篇 |
1991年 | 14篇 |
1990年 | 14篇 |
1989年 | 15篇 |
1988年 | 13篇 |
1987年 | 9篇 |
1986年 | 16篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1965年 | 2篇 |
1964年 | 7篇 |
1963年 | 5篇 |
1961年 | 2篇 |
1959年 | 4篇 |
1958年 | 3篇 |
1957年 | 3篇 |
1956年 | 4篇 |
1955年 | 6篇 |
排序方式: 共有7133条查询结果,搜索用时 15 毫秒
11.
为了准确、快速地进行缺陷识别,介绍了一种新型的前馈神经网络模型,即径向基概率神经网络。与以往的算法相比,该方法具有分类识别精度高且速度快的优点。仿真获得了很好的结果。 相似文献
12.
研究了热传导方程的通解,进而提出激光热源形成的微观机理和热源形成过程的三个理论计算式。对激光热效应的应用具有指导意义。 相似文献
13.
This paper considers the equalisation problem in Quadrature Phase-Shift Keying (QPSK) modulated signals which have been distorted by the passage through a transmission channel. The channel is modelled as a Rician fading channel to simulate the behaviour of the transmission channel in the mobile satellite context. The equalisation is treated as the generalisation of the channel behaviour, and some algorithms with the structure of an artificial neural network using the Multilayer Perceptron, Volterra Series and Radial Basis Function are described. Results for the BER performance of typical transversal equalisers, with Square-Root Kalman adaptation algorithm, and algorithms with artificial neural network structure are also reported and evaluated. Improved performance is exhibited by the artificial neural network approaches. 相似文献
14.
ZnO压敏陶瓷最佳掺杂含量的理论计算 总被引:3,自引:0,他引:3
从对电子薄膜材料研究中得到的最佳掺杂含量定量理论推广到ZnO陶瓷材料。该理论建立了电子薄膜材料的某一物理性能与晶体结构、制备方法和掺杂剂含量之间的联系,给出了一个能够拟合实验曲线的具有确定物理意义的抛物线方程。该方程的极值点确定了最佳掺杂含量与晶体结构和制备方法之间的定量关系,进而得到了一个掺杂最佳含量的表达式。系统地分析了ZnO压敏陶瓷的掺杂改性的实验结果,应用此表达式定量计算了ZnO压敏陶瓷的最佳掺杂含量,定量计算的结果与实验数据相符合。该理论也适用于其他薄膜材料最佳掺杂含量的理论计算。 相似文献
15.
An orthogonal basis for the hyperbolic hybrid polynomial space 总被引:1,自引:0,他引:1
Motivated by the wide usage of the Tchebyshev basis and Legendre basis in the algebra polynomial space, we construct an orthogonal basis with the properties of the H-Bézier basis in the hyperbolic hybrid polynomial space, which is similar to the Legendre basis and holds remarkable properties. Moreover, we derive the transformation matrices that map the H-Bézier basis and the orthogonal basis forms into each other. An example for approximating the degree reduction of the H- Bézier curves is sketched to illustrate the utility of the orthogonal basis. 相似文献
16.
Gülü Insel Derin Orhon Peter A Vanrolleghem 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2003,78(4):437-445
Hydrolysis mechanism plays a dominant role in the delicate balance of electron donor/electron acceptor ratios in BNR and EBPR systems as an important carbon source. In this study, the surface‐saturation‐type hydrolysis kinetics was investigated based on respirometric measurements, within the context of the theoretical and the practical identifiability of mathematical models. The identifiable parameters of a selected model were derived from respirograms. In addition, the information from the experiments was evaluated on the basis of Optimal Experimental Design (OED) methodology for different initial conditions of the batch respirometric experiment. © 2003 Society of Chemical Industry 相似文献
17.
The boundary knot method (BKM) of very recent origin is an inherently meshless, integration‐free, boundary‐type, radial basis function collocation technique for the numerical discretization of general partial differential equation systems. Unlike the method of fundamental solutions, the use of non‐singular general solution in the BKM avoids the unnecessary requirement of constructing a controversial artificial boundary outside the physical domain. The purpose of this paper is to extend the BKM to solve 2D Helmholtz and convection–diffusion problems under rather complicated irregular geometry. The method is also first applied to 3D problems. Numerical experiments validate that the BKM can produce highly accurate solutions using a relatively small number of knots. For inhomogeneous cases, some inner knots are found necessary to guarantee accuracy and stability. The stability and convergence of the BKM are numerically illustrated and the completeness issue is also discussed. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
18.
网络分解法是求解电大尺寸复杂结构电磁问题的重要方法之一,关于网络分解法误差分析的研究有着重要的理论意义和实用价值.本文给出了网络分解法的误差估计,并对于脉冲基函数转换成三角基函数的情况给出了三角基函数个数的最优公式,数值结果表明了分析的正确性. 相似文献
19.
20.
This study is based on a theoretical and photoelastic static contact stress analysis, relevant to the design of the plastic tibial plateau in an orthopaedic knee prosthesis. It involves the review of existing theoretical analyses concerned with the contact mechanics of layered elastic systems and, where possible, the validation of any relevant findings using two dimensional photoelasticity. Significant findings include the identification of a general minimum recommendable design thickness for the plastic tibial plateau, the endorsement of using the Hertzian contact theory to predict contact stress levels in the tibial plateau of certain knee implants and the slight improvement in contact conditions in the plastic when the plateau is perfectly bonded to its supporting metal tray. 相似文献