全文获取类型
收费全文 | 685篇 |
免费 | 13篇 |
国内免费 | 23篇 |
专业分类
电工技术 | 8篇 |
综合类 | 14篇 |
化学工业 | 77篇 |
金属工艺 | 17篇 |
机械仪表 | 51篇 |
建筑科学 | 25篇 |
矿业工程 | 4篇 |
能源动力 | 42篇 |
轻工业 | 2篇 |
水利工程 | 3篇 |
石油天然气 | 9篇 |
武器工业 | 1篇 |
无线电 | 110篇 |
一般工业技术 | 207篇 |
冶金工业 | 12篇 |
原子能技术 | 4篇 |
自动化技术 | 135篇 |
出版年
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 11篇 |
2020年 | 11篇 |
2019年 | 19篇 |
2018年 | 15篇 |
2017年 | 15篇 |
2016年 | 15篇 |
2015年 | 23篇 |
2014年 | 33篇 |
2013年 | 36篇 |
2012年 | 29篇 |
2011年 | 55篇 |
2010年 | 40篇 |
2009年 | 51篇 |
2008年 | 48篇 |
2007年 | 36篇 |
2006年 | 45篇 |
2005年 | 31篇 |
2004年 | 30篇 |
2003年 | 26篇 |
2002年 | 21篇 |
2001年 | 19篇 |
2000年 | 18篇 |
1999年 | 12篇 |
1998年 | 13篇 |
1997年 | 8篇 |
1996年 | 9篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1985年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有721条查询结果,搜索用时 15 毫秒
51.
提出了用“平面圆图”输出电机动态性能数值仿真波形的新方法.该方法在极坐标上以动画方式输出仿真结果,较之传统的xy平面直角坐标系,其突出优点是能够显示更大时域范围的仿真信息.文中结合ALA转子电机仿真实例对这种方法加以说明. 相似文献
52.
K.B. broberg 《International Journal of Fracture》1998,93(1-4):1-12
An analytic solution is given for a crack expanding with constant velocity from zero length in an anisotropic material under
anti-plane strain. Not all anisotropic materials can support anti-plane strain, and the study is therefore by necessity limited
to a certain class of materials, including monoclinic materials. A double Laplace transform is used and the inversion technique
is based on the self-similarity of the problem. The result shows that the crack shape is elliptic, as in the corresponding
isotropic case. The displacement on the crack plane outside the crack is found to be zero. Expressions are given for the stresses,
the stress intensity factor and the energy flux into the crack edge. In contrast to the isotropic case a transverse normal
stress may appear, singular at the crack edge.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
53.
MARKTRAN II is an interactive FORTRAN IV program that computes Markov transition probabilities for two-dimensional patterns. The pattern is represented by a series of discrete states at each point on a rectangular grid composed of square cells. Transition probabilities in eight directions are computed. MARKTRAN II is useful for numerically describing the fabric of patterns that possess any degree of anisotropy. Geological applications include analysis of rock fabrics, outcrop patterns of geological maps, and variations in ore grade expressed as discrete states. 相似文献
54.
本论文研究基于各向异性扩散的偏微分方程除去图像噪声的方法,在去除噪声的同时,能有效保持重要的边缘和局部细节,在通常考虑4向扩散方向的基础上提出了八向的各向异性扩散和边缘增强的处理技术,并将平滑后的图像通过聚类分群而得到不同的医学器官组织的分布。 相似文献
55.
The meshless local Petrov–Galerkin method is used to analyze transient heat conduction in 3-D axisymmetric solids with continuously inhomogeneous and anisotropic material properties. A 3-D axisymmetric body is created by rotation of a cross section around an axis of symmetry. Axial symmetry of geometry and boundary conditions reduces the original 3-D boundary value problem into a 2-D problem. The cross section is covered by small circular subdomains surrounding nodes randomly spread over the analyzed domain. A unit step function is chosen as test function, in order to derive local integral equations on the boundaries of the chosen subdomains, called local boundary integral equations. These integral formulations are either based on the Laplace transform technique or the time difference approach. The local integral equations are nonsingular and take a very simple form, despite of inhomogeneous and anisotropic material behavior across the analyzed structure. Spatial variation of the temperature and heat flux (or of their Laplace transforms) at discrete time instants are approximated on the local boundary and in the interior of the subdomain by means of the moving least-squares method. The Stehfest algorithm is applied for the numerical Laplace inversion, in order to retrieve the time-dependent solutions. 相似文献
56.
The PMMA/SWNT composites with good uniformity, dispersion and alignment of SWNT were fabricated in a stretching process. The semidried mixture was stretched along one direction at a draw ratio of 50 before it was dried, and then folded along the same direction stretching repeatedly for 100 times. The TEM and SEM observation demonstrated that SWNT in the PMMA/SWNT composite tend to align in the stretching direction. The electrical conductivity and the mechanical properties of composite rise with the increase of SWNT concentration, composite films showed higher conductivity and higher mechanical draw ratios along the stretched direction than perpendicular to it. The TGA revealed that embedding the SWNTs into the PMMA matrix also improves the thermal stability of the composite. 相似文献
57.
A new numerical method to calculate the stress intensity factors (SIFs) of a three-dimensional interface crack between dissimilar anisotropic materials was developed. In this study, the M-integral method was employed for mode separation of the SIFs. The moving least-square method was utilized to calculate the M-integral. Using the M-integral with the moving least-square method, SIFs can be automatically calculated with only the nodal displacements from the finite element method (FEM). Here, SIFs analyses of some typical three-dimensional problems are demonstrated. Excellent agreement was achieved between the numerical results obtained by the present method and the corresponding results proposed by other researchers. In addition, the SIFs of a single-edge crack, a through crack, and a semi-circular crack between two anisotropic solids in three-dimensional structures were analyzed. 相似文献
58.
Interaction between screw dislocations and a partially debonded interface in cylindrically anisotropic composites subjected
to uniform stress at infinity is investigated in this paper. Using Muskhelishvili’s complex variable method, the closed forms
of complex potentials are obtained for a screw dislocation and a screw dislocation dipole located inside either matrix or
inhomogeneity. Explicit expressions of stress intensity factors at the crack tips, image forces and image torques acting on
dislocation or the center of dipole are provided. The results show that the crack and dislocation geometry combination plays
an important role in the interaction between screw dislocations and interface crack. Furthermore, it is found that the anisotropy
of solids may change the shielding and anti-shielding effects arising from screw dislocations and the equilibrium position
of screw dislocations. The presented solutions are valid for anisotropic, orthotropic or isotropic composites and can be reduced
to some novel or previously known results. 相似文献
59.
李鹏 《中国图象图形学报》2013,18(10)
在文中我们首先分析了进行图像放大时各向异性偏微分方程优于各向同性偏微分方程,随后我们分析了在本文中不同四阶模型的扩散方向.为了消除低阶偏微分方程在处理图像中出现的块状效应的影响,同时保证方程为各向异性扩散,我们构造了两个各向异性的四阶偏微分方程,并且分别从数据和放大图像效果两方面来说明我们给出的模型优于文中提到的其它四个模型. 相似文献
60.
Membranes consisting of two layers, one of which has a concentration-dependent permeability, may show anisotropic fluxes. In other words, the flux under a given concentration difference has a different magnitude if the direction of the concentration difference is reversed but its magnitude is unchanged. This paper develops a simple theory of this effect and verifies aspects of this theory experimentally. 相似文献