全文获取类型
收费全文 | 34483篇 |
免费 | 3763篇 |
国内免费 | 2099篇 |
专业分类
电工技术 | 2361篇 |
技术理论 | 3篇 |
综合类 | 2974篇 |
化学工业 | 5314篇 |
金属工艺 | 2093篇 |
机械仪表 | 2189篇 |
建筑科学 | 2625篇 |
矿业工程 | 1118篇 |
能源动力 | 908篇 |
轻工业 | 3303篇 |
水利工程 | 782篇 |
石油天然气 | 1521篇 |
武器工业 | 352篇 |
无线电 | 3942篇 |
一般工业技术 | 3806篇 |
冶金工业 | 1413篇 |
原子能技术 | 524篇 |
自动化技术 | 5117篇 |
出版年
2024年 | 178篇 |
2023年 | 568篇 |
2022年 | 1191篇 |
2021年 | 1690篇 |
2020年 | 1231篇 |
2019年 | 964篇 |
2018年 | 1087篇 |
2017年 | 1212篇 |
2016年 | 1075篇 |
2015年 | 1557篇 |
2014年 | 2119篇 |
2013年 | 2393篇 |
2012年 | 2627篇 |
2011年 | 2797篇 |
2010年 | 2453篇 |
2009年 | 2289篇 |
2008年 | 2411篇 |
2007年 | 2190篇 |
2006年 | 1982篇 |
2005年 | 1627篇 |
2004年 | 1178篇 |
2003年 | 918篇 |
2002年 | 927篇 |
2001年 | 775篇 |
2000年 | 608篇 |
1999年 | 485篇 |
1998年 | 316篇 |
1997年 | 254篇 |
1996年 | 233篇 |
1995年 | 210篇 |
1994年 | 189篇 |
1993年 | 129篇 |
1992年 | 104篇 |
1991年 | 67篇 |
1990年 | 47篇 |
1989年 | 36篇 |
1988年 | 31篇 |
1987年 | 34篇 |
1986年 | 19篇 |
1985年 | 23篇 |
1984年 | 15篇 |
1983年 | 11篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 15篇 |
1979年 | 10篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1974年 | 5篇 |
1959年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
101.
102.
103.
GENERATION OF NONLINEAR INTERNAL WAVES ON CONTINENTAL SHELF 总被引:4,自引:4,他引:0
Xu Zhao ting Yao Feng chao Wang Mei Physical Oceanography Laboratory Institute of Physical Oceanography Ocean University of Qingdao China Key Laboratory of Marine Science Numerical Modeling State Oceanic Administration Qingdao 《水动力学研究与进展(B辑)》2001,(3)
1 . INTRODUCTIONInternaltidalinteractionwithbottomfeaturesappearstobethedominantmechanismforgenera tionofthecoherentoceanicinternalwavesthatareobservablewithSAR ,closertoshore ,riverineorglacialintrusionandcontinentalbreakprovidesec ondarygeneratingmecha… 相似文献
104.
Van Vo N. Shi Xue Dou Hua Kun Liu 《Applied Superconductivity, IEEE Transactions on》1996,6(2):102-105
High temperature superconducting (HTSC) multifilamentary (MT) Bi(Pb)-2223/Ag tapes with reproducible critical current density of between 15000 and 20000 A/cm2 at 77 K in self field have been achieved using the standard flat-rolling method as the intermediate deformation between sintering periods. Long lengths of Bi(Pb)-2223/Ag MT tapes up to 43 m prepared by the conventional method of powder-in-tube (PIT) have been successfully produced on a laboratory scale. Several coils have been fabricated from sections of the long length tape, using the co-wound wind-and-react (W&R) procedure for the pancake-shaped and the singly-wound W&R as well as R&W procedure for the solenoidal coils. A novel W&R solenoidal coil (reaching ~973 ampere-turns) wound on an alumina ceramic tube generates a DC field of ~19 mT at 77 K and has been fabricated together with five pancake-shaped coils, each generating an average of ~5 mT at 77 K. These are destined for magnet construction with a possible combined calculated field of ~0.04 T at 77 K (with liquid nitrogen as a coolant) 相似文献
105.
106.
107.
With the aid of a double-tilt holder in a transmission electron microscope, a new method for a rapid and precise determination of the misorientations of a large number of subgrain or grain boundaries is given in this article. By use of the method, the continuous recrystallization can be rapidly and precisely evaluated when compared to the other conventional methods. 相似文献
108.
It is shown that a superconductor cannot be simply treated as a low-loss conductor; rather, it should be treated as a negative dielectric material (with a negative dielectric constant). This approach is good only for vanishingly small field application with frequency significantly smaller than gap frequency and temperature not too close to the critical temperature of the superconductor. The electromagnetics of negative dielectric materials are discussed in terms of causality, perturbation technique, surface impedance, time-domain interpretation of current components, and computational electrodynamics 相似文献
109.
A modification to the time-domain finite-difference method (TDFDM) that uses a variable step size is investigated. The entire computational volume is divided into a coarse grid with a large step size. A fine grid with a small step size is introduced only around discontinuities. The corresponding time increments are related to the spatial increments with the same ratio in order to minimize the numerical dispersion. The fields within the coarse and fine grids are found using the TDFDM, while an interpolation in space and time is utilized to calculate the tangential electric field on the coarse-fine grid boundary. This subgridding decreases the required computer memory and therefore expands the capability of the TDFDM. The technique is shown to be numerically stable and does not entail any extra numerical error. The method is applied to the calculation of waveguides and microstrips 相似文献
110.