全文获取类型
收费全文 | 337317篇 |
免费 | 37043篇 |
国内免费 | 12951篇 |
专业分类
电工技术 | 18454篇 |
技术理论 | 12篇 |
综合类 | 18489篇 |
化学工业 | 62541篇 |
金属工艺 | 18324篇 |
机械仪表 | 19735篇 |
建筑科学 | 22539篇 |
矿业工程 | 7370篇 |
能源动力 | 8406篇 |
轻工业 | 25833篇 |
水利工程 | 6460篇 |
石油天然气 | 15927篇 |
武器工业 | 2296篇 |
无线电 | 41029篇 |
一般工业技术 | 52426篇 |
冶金工业 | 18089篇 |
原子能技术 | 6434篇 |
自动化技术 | 42947篇 |
出版年
2024年 | 849篇 |
2023年 | 4260篇 |
2022年 | 7882篇 |
2021年 | 12013篇 |
2020年 | 9925篇 |
2019年 | 9908篇 |
2018年 | 11270篇 |
2017年 | 12789篇 |
2016年 | 12262篇 |
2015年 | 14625篇 |
2014年 | 17917篇 |
2013年 | 22147篇 |
2012年 | 21639篇 |
2011年 | 23231篇 |
2010年 | 20572篇 |
2009年 | 20021篇 |
2008年 | 19331篇 |
2007年 | 18043篇 |
2006年 | 16796篇 |
2005年 | 14012篇 |
2004年 | 10312篇 |
2003年 | 9423篇 |
2002年 | 9338篇 |
2001年 | 8344篇 |
2000年 | 7436篇 |
1999年 | 6473篇 |
1998年 | 5144篇 |
1997年 | 4361篇 |
1996年 | 3887篇 |
1995年 | 3362篇 |
1994年 | 2769篇 |
1993年 | 2305篇 |
1992年 | 2013篇 |
1991年 | 1718篇 |
1990年 | 1598篇 |
1989年 | 1398篇 |
1988年 | 1219篇 |
1987年 | 1056篇 |
1986年 | 949篇 |
1985年 | 869篇 |
1984年 | 808篇 |
1983年 | 737篇 |
1982年 | 745篇 |
1981年 | 739篇 |
1979年 | 781篇 |
1978年 | 807篇 |
1977年 | 775篇 |
1976年 | 811篇 |
1974年 | 738篇 |
1973年 | 745篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
952.
953.
V. V. Shilov Yu. P. Gomza V. N. Bliznyuk Yu. S. Lipatov D. B. Boguslavsky V. L. Pikalov Z. F. Suvorova 《应用聚合物科学杂志》1985,30(5):1927-1934
The structural peculiarities of cis-1,4-isoprene rubber, oligodiene diisocyanate, and derivative of phenol–formaldehyde resin blends have been studied by WAXS and SAXS methods and electron microscopy. It has been demonstrated that the addition of modifiers and further thermal treatment under conventional curing conditions change considerably the microheterogeneous structure and morphology and contribute to the improvement of the short-range order in the rubber matrix. 相似文献
954.
Random vibration analysis of flexible rotor-bearing systems subjected to six-component nonstationary earthquake ground accelerations is carried out. The rotor system consists of several rigid disks and a flexible shaft that is modelled as a Timoshenko beam. The governing equations of motion involve both inhomogeneous random excitations and random parametric excitations. Analytically, the Markov vector approach using the Ito equation and Stratonovich averaging procedures is employed to determine the response statistics. Unfortunately, the second moments of the response quantities thus obtained involve a great discrepancy when compared with the results of Monte Carlo simulation. The difficulty involved in analytically solving such a complicated problem is pointed out. Currently, the method of Monte Carlo simulation appears to be the only practical approach for such a problem. The significant influence of the seismic base rotations and the flexibility of the rotor-bearing system on the overall dynamic structural response is demonstrated by a numerical example. 相似文献
955.
956.
957.
958.
Yu. A. Radin I. A. Grishin T. S. Kontorovich O. B. Panshina A. V. Chugin 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2006,40(2):113-119
Problems arising with connecting the second exhaust-heat boiler to the first exhaust-heat boiler under load in the case of
flow circuits of combined-cycle plants of type PGU-450 are considered. Similar problems exist for two-boiler single-turbine
units of type PGU-325 and for two-boiler single-turbine units of traditional steampower plants with an output of 200–300 MW
upon connection of the second furnace of a two-furnace boiler to the operating first furnace. Analysis of the temperature-induced
stressed state and of the cyclic strength of thick-walled elements of the steam-water conduit of PGU-450 and of two-furnace
boilers of two-boiler single-turbine units with an output of 200–300 MW (the check valve, the inlet header of the water economizer)
is used for determining the steam temperature differences in the high-pressure conduits to the steam turbine and the order
of connection of the second exhaust-heat boiler to the operating fist one. Modes of enabling a two-boiler single-turbine unit
of a combined-cycle plant, which are most “rigid” from the standpoint of thermal strength, are determined.
__________
Translated from élektricheskie Stantsii, No. 2, February 2006, pp. 11–17. 相似文献
959.
O. T. Tsyrul’nyk H. M. Nykyforchyn D. Yu. Petryna M. I. Hredil’ I. M. Dz’oba 《Materials Science》2007,43(5):708-717
We study the degradation of the mechanical and corrosion properties of 17G1S steel in gas mains as a result of operation for
28–40 yr. We reveal the simultaneous decrease in its strength and hardness, on the one hand, and impact toughness and crack
resistance, on the other hand. The indicated parameters prove to be most sensitive to the in-service degradation of the metal.
The degradation of steel leads to the increase in the strain-hardening coefficient and the appearance of the yield plateau
in the tensile stress-strain diagram and causes the appearance of sensitivity to hydrogen embrittlement increasing in the
process of operation. We analyze the role of absorbed hydrogen affecting the mechanism of strain aging and responsible for
the appearance of defects. It is shown that the polarization resistance can be used not only for monitoring of the corrosion
state of gas pipelines but also for the prediction of changes in their mechanical properties in the process of operation.
__________
Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 43, No. 5, pp. 97–104, September–October, 2007. 相似文献
960.