全文获取类型
收费全文 | 23234篇 |
免费 | 320篇 |
国内免费 | 118篇 |
专业分类
电工技术 | 498篇 |
综合类 | 64篇 |
化学工业 | 3171篇 |
金属工艺 | 939篇 |
机械仪表 | 657篇 |
建筑科学 | 549篇 |
矿业工程 | 67篇 |
能源动力 | 601篇 |
轻工业 | 1836篇 |
水利工程 | 224篇 |
石油天然气 | 179篇 |
武器工业 | 1篇 |
无线电 | 2589篇 |
一般工业技术 | 4069篇 |
冶金工业 | 6129篇 |
原子能技术 | 419篇 |
自动化技术 | 1680篇 |
出版年
2021年 | 151篇 |
2020年 | 123篇 |
2019年 | 157篇 |
2018年 | 229篇 |
2017年 | 229篇 |
2016年 | 255篇 |
2015年 | 188篇 |
2014年 | 297篇 |
2013年 | 819篇 |
2012年 | 507篇 |
2011年 | 775篇 |
2010年 | 558篇 |
2009年 | 621篇 |
2008年 | 715篇 |
2007年 | 745篇 |
2006年 | 629篇 |
2005年 | 718篇 |
2004年 | 587篇 |
2003年 | 634篇 |
2002年 | 675篇 |
2001年 | 670篇 |
2000年 | 599篇 |
1999年 | 614篇 |
1998年 | 2158篇 |
1997年 | 1402篇 |
1996年 | 1043篇 |
1995年 | 718篇 |
1994年 | 618篇 |
1993年 | 640篇 |
1992年 | 358篇 |
1991年 | 344篇 |
1990年 | 341篇 |
1989年 | 343篇 |
1988年 | 292篇 |
1987年 | 267篇 |
1986年 | 245篇 |
1985年 | 275篇 |
1984年 | 215篇 |
1983年 | 200篇 |
1982年 | 185篇 |
1981年 | 217篇 |
1980年 | 202篇 |
1979年 | 164篇 |
1978年 | 152篇 |
1977年 | 277篇 |
1976年 | 385篇 |
1975年 | 127篇 |
1974年 | 109篇 |
1973年 | 117篇 |
1972年 | 90篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Modelling and characterization of AlN-actuated microcantilevers vibrating in the first in-plane mode
V. Ruiz J. Hernando-García A. Ababneh H. Seidel U. Schmid J. L. Sánchez-Rojas 《Microsystem Technologies》2012,18(7-8):997-1001
The characterization of the first in-plane mode of aluminum nitride-actuated piezoelectric microcantilevers was carried out by using electrical and optical techniques. The top electrode of the cantilever was specifically designed to allow for an efficient electrical actuation of these in-plane modes. In order to confirm the in-plane nature of the modal vibration, the detection of the electrically induced movement was performed optically with the help of a stroboscopic microscope. In parallel, resonances were also measured electrically by means of an impedance analyzer. The quality factor and the resonant frequencies of the in-plane modes were estimated from the corresponding measurement data when applying both detection techniques. Our results show quality factor values as high as 3,000 for the first in-plane mode in air. 相似文献
993.
994.
In this project, several docking conditions, scoring functions and corresponding protein-aligned molecular field analysis (CoMFA) models were evaluated for a diverse set of neuraminidase (NA) inhibitors. To this end, a group of inhibitors were docked into the active site of NA. The docked structures were utilized to construct a corresponding protein-aligned CoMFA models by employing probe-based (H+, OH, CH3) energy grids and genetic partial least squares (G/PLS) statistical analysis. A total of 16 different docking configurations were evaluated, of which some succeeded in producing self-consistent and predictive CoMFA models. However, the best model coincided with docking the ionized ligands into the hydrated form of the binding site via PLP1 scoring function (r2LOO=0.735, r2PRESS against 24 test compounds=0.828). The highest-ranking CoMFA models were employed to probe NA-ligand interactions. Further validation by comparison with a co-crystallized ligand-NA crystallographic structure was performed. This combination of docking/scoring/CoMFA modeling provided interesting insights into the binding of different NA inhibitors. 相似文献
995.
996.
997.
998.
U V Varadaraju G V Subba Rao K D Chandrasekaran A Baradarajan K Krishnaiah Mukesh Agarwala V S Achutharaman P Venugopal K A Padmanabhan L S Vaidyanathan G Rangarajan 《Bulletin of Materials Science》1989,12(1):63-80
The oxygen-deficient phase of the highT
c superconductor, YBa2Cu3O7, was oxygen-enriched using the fluidization technique to give good superconducting properties. The normal method of oxygen
treatment at 900°C for 24 h and at 600°C for 24 h has been reduced to just one treatment at 600°C for 12 h by the fluidization
technique to achieve almost the same strength of superconducting signal for the YBa2Cu3O7 powder, which establishes the attractiveness of the latter route for the large-scale preparation of superconducting material.
The particle sizes were in the range 0–90, 90–180 and 180–420 μm. The fluidized particles were crystalline with orthorhombic
distortion.T
c
onset
, estimated using the a.c. magnetic susceptibility method, was 91·3 K. The volume fraction of superconducting material in
the product was 83·7–85·3%, one of the highest values reported so far for YBa2Cu3O7. 相似文献
999.
A study is made of the filling, with a fluid, of a model medium consisting of two interacting continua whose interpenetrating pore spaces are formed of pores that are roughly identical within the confines of the respective continua.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 56, No. 6, pp. 953–960, June, 1989. 相似文献
1000.