全文获取类型
| 收费全文 | 860篇 |
| 免费 | 13篇 |
| 国内免费 | 4篇 |
专业分类
| 电工技术 | 13篇 |
| 综合类 | 1篇 |
| 化学工业 | 211篇 |
| 金属工艺 | 13篇 |
| 机械仪表 | 24篇 |
| 建筑科学 | 19篇 |
| 矿业工程 | 5篇 |
| 能源动力 | 31篇 |
| 轻工业 | 53篇 |
| 水利工程 | 7篇 |
| 石油天然气 | 3篇 |
| 无线电 | 159篇 |
| 一般工业技术 | 128篇 |
| 冶金工业 | 72篇 |
| 原子能技术 | 6篇 |
| 自动化技术 | 132篇 |
出版年
| 2024年 | 24篇 |
| 2023年 | 9篇 |
| 2022年 | 30篇 |
| 2021年 | 32篇 |
| 2020年 | 37篇 |
| 2019年 | 34篇 |
| 2018年 | 29篇 |
| 2017年 | 31篇 |
| 2016年 | 60篇 |
| 2015年 | 22篇 |
| 2014年 | 37篇 |
| 2013年 | 58篇 |
| 2012年 | 43篇 |
| 2011年 | 44篇 |
| 2010年 | 34篇 |
| 2009年 | 36篇 |
| 2008年 | 27篇 |
| 2007年 | 28篇 |
| 2006年 | 17篇 |
| 2005年 | 25篇 |
| 2004年 | 8篇 |
| 2003年 | 16篇 |
| 2002年 | 8篇 |
| 2001年 | 18篇 |
| 2000年 | 4篇 |
| 1999年 | 11篇 |
| 1998年 | 30篇 |
| 1997年 | 17篇 |
| 1996年 | 11篇 |
| 1995年 | 11篇 |
| 1994年 | 7篇 |
| 1993年 | 4篇 |
| 1992年 | 4篇 |
| 1991年 | 6篇 |
| 1990年 | 9篇 |
| 1989年 | 4篇 |
| 1988年 | 4篇 |
| 1987年 | 3篇 |
| 1986年 | 6篇 |
| 1985年 | 3篇 |
| 1984年 | 4篇 |
| 1983年 | 4篇 |
| 1982年 | 3篇 |
| 1980年 | 3篇 |
| 1979年 | 3篇 |
| 1975年 | 3篇 |
| 1974年 | 3篇 |
| 1973年 | 4篇 |
| 1969年 | 2篇 |
| 1965年 | 1篇 |
排序方式： 共有877条查询结果，搜索用时 0 毫秒
821.
822.
Abe T Hung VN Esashi M 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2006,53(7):1234-1236
In this letter, we present experimental data showing Q change versus thickness for a quartz-crystal resonator fabricated with deep-reactive ion etching. Measurements show that Q increases as etch depth increases, and further that Q can be optimized as a function of etch depth and diameter of the resonator. 相似文献
823.
A numerical study is conducted to analyse the two-dimensional incompressible Navier-Stokes flows through the rectilinear and radial cascade of turbine blades. The flows are turbulent and their characteristics are relevant to those of the hydraulic turbines. For the rectilinear cascade, calculations have been made for a NACA 80 series turbine blade with various angles of attack. The outflow turning angle, force coefficients and static pressure distribution have been compared between the prediction and measurement with satisfactory agreements being obtained. The implications of flow turning angles on the total pressure loss are also discussed. The effects of grid distribution on the numerical predictions are also observed. 相似文献
824.
825.
G Manfredi T Vu E Bonilla EA Schon S DiMauro E Arnaudo L Zhang LP Rowland M Hirano 《Canadian Metallurgical Quarterly》1997,42(2):180-188
We identified large-scale heteroplasmic mitochondrial DNA (mtDNA) rearrangements in a 50-year-old woman with an adult-onset progressive myopathy. The predominant mtDNA abnormality was a 21.2-kb duplicated molecule. In addition, a small population of the corresponding partially deleted 4.6-kb molecule was detected. Skeletal muscle histology revealed fibers that were negative for cytochrome c oxidase (COX) activity and had reduced mtDNA-encoded COX subunits. By single-fiber polymerase chain reaction analysis, COX-negative fibers contained a low number of wild-type or duplicated mtDNA molecules (ie, nondeleted). In situ hybridization demonstrated that the abnormal fibers contained increased amounts of mtDNA compared with normal fibers and that most of the genomes were deleted. We concluded that deleted mtDNA molecules were primarily responsible for the phenotype in this patient. 相似文献
826.
M Misrahi I Beau N Ghinea B Vannier H Loosfelt G Meduri MT Vu Hai E Milgrom 《Canadian Metallurgical Quarterly》1996,125(1-2):161-167
827.
X. G. Tan L. Vu‐Quoc 《International journal for numerical methods in engineering》2005,64(15):1981-2013
In this paper, we present an optimal low‐order accurate piezoelectric solid‐shell element formulation to model active composite shell structures that can undergo large deformation and large overall motion. This element has only displacement and electric degrees of freedom (dofs), with no rotational dofs, and an optimal number of enhancing assumed strain (EAS) parameters to pass the patch tests (both membrane and out‐of‐plane bending). The combination of the present optimal piezoelectric solid‐shell element and the optimal solid‐shell element previously developed allows for efficient and accurate analyses of large deformable composite multilayer shell structures with piezoelectric layers. To make the 3‐D analysis of active composite shells containing discrete piezoelectric sensors and actuators even more efficient, the composite solid‐shell element is further developed here. Based on the mixed Fraeijs de Veubeke–Hu–Washizu (FHW) variational principle, the in‐plane and out‐of‐plane bending behaviours are improved via a new and efficient enhancement of the strain tensor. Shear‐locking and curvature thickness locking are resolved effectively by using the assumed natural strain (ANS) method. We also present an optimal‐control design for vibration suppression of a large deformable structure based on the general finite element approach. The linear‐quadratic regulator control scheme with output feedback is used as a control law on the basis of the state space model of the system. Numerical examples involving static analyses and dynamic analyses of active shell structures having a large range of element aspect ratios are presented. Active vibration control of a composite multilayer shell with distributed piezoelectric sensors and actuators is performed to test the present element and the control design procedure. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
828.
Thu Hang Vu Andrew J. Deeks 《International journal for numerical methods in engineering》2006,65(10):1714-1733
The scaled boundary finite element method is a novel semi‐analytical technique, whose versatility, accuracy and efficiency are not only equal to, but potentially better than the finite element method and the boundary element method for certain problems. This paper investigates the possibility of using higher‐order polynomial functions for the shape functions. Two techniques for generating the higher‐order shape functions are investigated. In the first, the spectral element approach is used with Lagrange interpolation functions. In the second, hierarchical polynomial shape functions are employed to add new degrees of freedom into the domain without changing the existing ones, as in the p‐version of the finite element method. To check the accuracy of the proposed procedures, a plane strain problem for which an exact solution is available is employed. A more complex example involving three scaled boundary subdomains is also addressed. The rates of convergence of these examples under p‐refinement are compared with the corresponding rates of convergence achieved when uniform h‐refinement is used, allowing direct comparison of the computational cost of the two approaches. The results show that it is advantageous to use higher‐order elements, and that higher rates of convergence can be obtained using p‐refinement instead of h‐refinement. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
829.
830.