全文获取类型
收费全文 | 1394篇 |
免费 | 271篇 |
国内免费 | 171篇 |
专业分类
电工技术 | 64篇 |
综合类 | 155篇 |
化学工业 | 88篇 |
金属工艺 | 42篇 |
机械仪表 | 50篇 |
建筑科学 | 99篇 |
矿业工程 | 16篇 |
能源动力 | 34篇 |
轻工业 | 7篇 |
水利工程 | 24篇 |
石油天然气 | 103篇 |
武器工业 | 2篇 |
无线电 | 327篇 |
一般工业技术 | 470篇 |
冶金工业 | 12篇 |
原子能技术 | 27篇 |
自动化技术 | 316篇 |
出版年
2024年 | 8篇 |
2023年 | 33篇 |
2022年 | 28篇 |
2021年 | 43篇 |
2020年 | 53篇 |
2019年 | 59篇 |
2018年 | 62篇 |
2017年 | 73篇 |
2016年 | 68篇 |
2015年 | 52篇 |
2014年 | 72篇 |
2013年 | 135篇 |
2012年 | 97篇 |
2011年 | 103篇 |
2010年 | 85篇 |
2009年 | 81篇 |
2008年 | 101篇 |
2007年 | 101篇 |
2006年 | 95篇 |
2005年 | 73篇 |
2004年 | 62篇 |
2003年 | 46篇 |
2002年 | 49篇 |
2001年 | 40篇 |
2000年 | 41篇 |
1999年 | 28篇 |
1998年 | 32篇 |
1997年 | 23篇 |
1996年 | 20篇 |
1995年 | 12篇 |
1994年 | 11篇 |
1993年 | 15篇 |
1992年 | 3篇 |
1991年 | 9篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
排序方式: 共有1836条查询结果,搜索用时 31 毫秒
31.
纺织面料的物理仿真将虚拟现实与纺织CAD相结合,是虚拟服装与试衣系统研究的一项关键技术,纺织品建模也是纺织品真实感模拟的基础及关键工作.在基于物理的粒子系统的基础上,提出各向异性的建模方式.根据织物面料的不同组织方式进行分析,对其进行经纬方向的分离建模.仿真过程分为初始过程的刚性物体模拟和接近平衡时的柔性物质模拟两大步骤.为了在产生逼真表现效果的同时兼顾计算复杂性,构模时引入多分辨率模型. 相似文献
32.
在研究非线性扩散方法图像去噪的基础上,针对非线性系数扩散问题,提出了应用图像方向信息控制扩散系数的非线性扩散方法,该方法利用方向信息测度来表征图像的区域性质,不仅降低了噪声的干扰,而且克服了其他方法必须先进行高斯卷积的影响,并有效控制了各点的扩散行为。实验结果证明该方法是可行的,该方法在图像去噪的同时保持了图像的重要特征,取得比较理想的效果。 相似文献
33.
Nowadays in the medical field, imaging techniques such as Optical Coherence Tomography (OCT) are mainly used to identify retinal diseases. In this paper, the Central Serous Chorio Retinopathy (CSCR) image is analyzed for various stages and then compares the difference between CSCR before as well as after treatment using different application methods. The first approach, which was focused on image quality, improves medical image accuracy. An enhancement algorithm was implemented to improve the OCT image contrast and denoise purpose called Boosted Anisotropic Diffusion with an Unsharp Masking Filter (BADWUMF). The classifier used here is to figure out whether the OCT image is a CSCR case or not. 150 images are checked for this research work (75 abnormal from Optical Coherence Tomography Image Retinal Database, in-house clinical database, and 75 normal images). This article explicitly decides that the approaches suggested aid the ophthalmologist with the precise retinal analysis and hence the risk factors to be minimized. The total precision is 90 percent obtained from the Two Class Support Vector Machine (TCSVM) classifier and 93.3 percent is obtained from Shallow Neural Network with the Powell-Beale (SNNWPB) classifier using the MATLAB 2019a program. 相似文献
34.
传统彩色边缘检测算法在提高边缘检测准确性时可能将噪声检测为边缘,而在提高噪声鲁棒性时会将部分边缘当作噪声进行抑制,导致部分边缘信息丢失。为解决传统彩色边缘检测算法在边缘检测准确性与噪声鲁棒性之间的矛盾问题,提出一种基于自适应各向异性高斯方向导数(ANDD)的彩色边缘检测算法。通过彩色图像的微分自相关矩阵构建反映边缘类型的度量准则,以自适应地确定每个像素处ANDD滤波器的形状,从而准确提取不同类型的边缘特征,采用ANDD滤波器组对图像进行平滑处理,提取在三个通道上的ANDD特征。在此基础上,利用奇异值分解得到最优融合权值,并融合三个通道的ANDD特征,以增强彩色边缘强度。实验结果表明,该算法在无噪声和含噪声环境下的Pratt品质因子分别为0.849 6和0.791 4,与彩色Canny、RCMG-MM和FRPOS算法相比,在保持较高边缘检测准确率的同时具有较优的噪声鲁棒性。 相似文献
35.
Shishir Gupta 《先进材料力学与结构力学》2017,24(1):64-72
The present work is concerned with a detailed illustration on the study of horizontally polarized shear waves (SH-type) propagation in a prestressed fluid saturated anisotropic porous layer sandwiched by prestressed orthotropic medium and nonhomogeneous mantles. The frequency equation for the assumed model is derived and their medium characteristics, such as porosity, prestress, anisotropy, and nonhomogeneity, are discussed. Numerical treatment is given to analyze these effects on phase velocities of SH-type waves and is plotted in various graphs. The parametric study divulges that the magnitude of wave velocities increases with the increase of nonhomogeneity parameter and prestress parameter. 相似文献
36.
A monotone nonlinear finite volume method for approximating diffusion operators on general meshes 下载免费PDF全文
Jean‐Sylvain Camier Francois Hermeline 《International journal for numerical methods in engineering》2016,107(6):496-519
The basic principles of the discrete duality and nonlinear monotone finite volume methods are combined in order to obtain a new monotone nonlinear finite volume method for the approximation of diffusion operators on general meshes. Numerical results highlight both the second‐order accuracy of this method on general meshes and its capability to deal with challenging anisotropic diffusion problems on various computational domains. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
37.
Soumen Jana Sheeny K. Lan Levengood Miqin Zhang 《Advanced materials (Deerfield Beach, Fla.)》2016,28(48):10588-10612
Repair of damaged skeletal‐muscle tissue is limited by the regenerative capacity of the native tissue. Current clinical approaches are not optimal for the treatment of large volumetric skeletal‐muscle loss. As an alternative, tissue engineering represents a promising approach for the functional restoration of damaged muscle tissue. A typical tissue‐engineering process involves the design and fabrication of a scaffold that closely mimics the native skeletal‐muscle extracellular matrix (ECM), allowing organization of cells into a physiologically relevant 3D architecture. In particular, anisotropic materials that mimic the morphology of the native skeletal‐muscle ECM, can be fabricated using various biocompatible materials to guide cell alignment, elongation, proliferation, and differentiation into myotubes. Here, an overview of fundamental concepts associated with muscle‐tissue engineering and the current status of muscle‐tissue‐engineering approaches is provided. Recent advances in the development of anisotropic scaffolds with micro‐ or nanoscale features are reviewed, and how scaffold topographical, mechanical, and biochemical cues correlate to observed cellular function and phenotype development is examined. Finally, some recent developments in both the design and utility of anisotropic materials in skeletal‐muscle‐tissue engineering are highlighted, along with their potential impact on future research and clinical applications. 相似文献
38.
39.
40.
Fernando Maccari Tarini Prasad Mishra Monica Keszler Tobias Braun Esmaeil Adabifiroozjaei Iliya Radulov Tianshu Jiang Enrico Bruder Olivier Guillon Leopoldo Molina-Luna Martin Bram Oliver Gutfleisch 《Advanced Engineering Materials》2023,25(18):2300252
Flash spark plasma sintering (flash SPS) is an attractive method to obtain Nd–Fe–B magnets with anisotropic magnetic properties when starting from melt-spun powders. Compared to the benchmark processing route via hot pressing with subsequent die upsetting, flash SPS promises electroplasticity as an additional deformation mechanism and reduced tool wear, while maximizing magnetic properties by tailoring the microstructure—fully dense and high texture. A detailed parameter study is conducted to understand the influence of Flash SPS parameters on the densification and magnetic properties of commercial MQU-F powder. It is revealed that the presintering conditions and preheating temperature before applying the power pulse play a major role for tailoring grain size and texture in the case of hot deformation via Flash SPS. Detailed microstructure and magnetic domain evaluation disclose the texture enhancement with increasing flash SPS temperature at the expense of coercivity. The best compromise between remanence and coercivity (1.37 T and 1195 kA m−1, respectively) is achieved through a combination of presintering at 500 °C for 120 s and preheating temperature of 600 °C, resulting in a magnet with energy product (BH)max of 350 kJm−3. These findings show the potential of flash SPS to obtain fully dense anisotropic nanocrystalline magnets with high magnetic performance. 相似文献