全文获取类型
收费全文 | 495299篇 |
免费 | 4698篇 |
国内免费 | 1242篇 |
专业分类
电工技术 | 7744篇 |
综合类 | 2544篇 |
化学工业 | 74636篇 |
金属工艺 | 26000篇 |
机械仪表 | 17814篇 |
建筑科学 | 10597篇 |
矿业工程 | 5169篇 |
能源动力 | 9538篇 |
轻工业 | 28791篇 |
水利工程 | 7041篇 |
石油天然气 | 15375篇 |
武器工业 | 33篇 |
无线电 | 49313篇 |
一般工业技术 | 109204篇 |
冶金工业 | 67702篇 |
原子能技术 | 14296篇 |
自动化技术 | 55442篇 |
出版年
2021年 | 3997篇 |
2019年 | 3937篇 |
2018年 | 21207篇 |
2017年 | 20396篇 |
2016年 | 17639篇 |
2015年 | 5064篇 |
2014年 | 7930篇 |
2013年 | 17933篇 |
2012年 | 14340篇 |
2011年 | 23745篇 |
2010年 | 19806篇 |
2009年 | 18746篇 |
2008年 | 20012篇 |
2007年 | 20791篇 |
2006年 | 11163篇 |
2005年 | 11134篇 |
2004年 | 10762篇 |
2003年 | 10591篇 |
2002年 | 9508篇 |
2001年 | 9019篇 |
2000年 | 8997篇 |
1999年 | 8499篇 |
1998年 | 17722篇 |
1997年 | 13252篇 |
1996年 | 10292篇 |
1995年 | 7887篇 |
1994年 | 7274篇 |
1993年 | 7252篇 |
1992年 | 5967篇 |
1991年 | 5972篇 |
1990年 | 5844篇 |
1989年 | 5801篇 |
1988年 | 5594篇 |
1987年 | 5228篇 |
1986年 | 4975篇 |
1985年 | 5534篇 |
1984年 | 5284篇 |
1983年 | 5014篇 |
1982年 | 4631篇 |
1981年 | 4796篇 |
1980年 | 4669篇 |
1979年 | 4895篇 |
1978年 | 5075篇 |
1977年 | 5342篇 |
1976年 | 6559篇 |
1975年 | 4578篇 |
1974年 | 4558篇 |
1973年 | 4641篇 |
1972年 | 4014篇 |
1971年 | 3717篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
111.
112.
R.V.R. PandyaF. Mashayek 《International Journal of Heat and Mass Transfer》2002,45(24):4753-4759
In this paper, effects of particles on the subgrid scales of turbulence are properly accounted for during the modeling of subgrid scale stresses in the large-eddy simulation (LES) of fluid phase. In doing so, we propose closed filtered kinetic equations for phase space density of the particle. The various moments of these equations give the `fluid' equations which can be considered as the LES equations for the particle phase. The influence of subgrid scales motion on the particles is included in these `fluid' equations. 相似文献
113.
114.
坦努尔坝是约旦的第一座RCC坝。该坝RCC铺筑采用斜层施工,提高工数50%。大坝上游面,下游台阶,阶梯式溢洪道,止水面以及RCC与坝肩石灰岩的交界面均采用GE-RCC。质量控制测试数据表明,该坝达到了国际大坝委员会会刊不久将发表的RCC坝质量标准的优良等级。 相似文献
115.
Validity on the well-known Onsager reciprocal relations L 12=L 21 is verified in the kinetic theory of gases taking into account mass and heat transfer near the surface. Using an analytical solution to the ellipsoidal statistical equation (providing for the true Prandtl number), it is demonstrated that the Onsager relations are obeyed, at least to within exponential corrections of the type exp(−1/Kn) in the Knudsen number. 相似文献
116.
B. A. Afanas'ev E. P. Vinogradova G. F. Smirnov 《Journal of Engineering Physics and Thermophysics》1985,49(4):1185-1191
The article presents the results of experimental investigations of critical (limit) heat fluxes upon evaporation on porous coatings, and it substantiates the physical model of the process.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 49, No. 4, pp. 607–614, October, 1985. 相似文献
117.
N. A. Sivov A. I. Martynenko G. N. Bondarenko M. P. Filatova E. Yu. Kabanova N. I. Popova A. N. Sivov E. B. Kruts’ko 《Petroleum Chemistry》2006,46(1):41-59
Structures and compositions of the monomers guanidine acrylate and guanidine methacrylate, their homopolymers, and copolymers with diallyldimethylammonium chloride enriched in acrylate comonomer units were determined. It was shown that ampholytic copolymers, owing to their ionic nature, contained comonomeric guanidine acrylate or methacrylate units and diallyldimethylammonium chloride units, as well as the acrylate comonomer with the diallyl counterion and polymeric acrylate and diallyl ion pairs. It follows from IR and 1H NMR data that guanidine methacrylate has the same structure (with two hydrogen bonds) in the solid state and in solutions. Guanidine acrylate structures in the solid state and in dimethylsulfoxide are identical and analogous to guanidine methacrylate structure in this solvent. In water, the guanidine acrylate structure has another type of hydrogen bonding (with one hydrogen bond, where the proton is shifted toward the guanidine group). These features of hydrogen bonding of guanidine acrylate and guanidine methacrylate are also retained in their homopolymers and copolymers with diallyldimethylammonium chloride. It was shown that the thermal stability of the copolymers was higher than that of their homopolymers, confirming the formation of intramolecular ion pairs of oppositely charged units of ampholytic copolymers. Moreover, the thermal stability of guanidine methacrylate-diallyldimethylammonium chloride copolymers is higher than that of guanidine acrylate-diallyldimethylammonium chloride copolymers. 相似文献
118.
It is established that the capillary rise of a liquid has an oscillatory character, in contrast to the commonly accepted opinion that a vertical capillary is filled at a monotonically varying velocity. The value of the tangential shear stress arising in an ascending liquid is evaluated for ethyl alcohol and distilled water. 相似文献
119.
A. M. Kozodaev O. V. Shvedov V. N. Konev B. Yu. Sharkov V. V. Vasil'ev E. B. Volkov N. V. Lazarev A. M. Raskopin G. G. Shimchuk P. V. Bogdanov A. I. Kiryushin V. V. Petrunin E. I. Azhnin E. I. Tyurin I. I. Titaev Yu. P. Severgin A. Yu. Konstantinov 《Atomic Energy》2003,94(1):56-60
The purpose and current construction status, at the Institute of Theoretical and Experimental Physics, of an experimental electronuclear setup, combining a pulsed proton linear accelerator (36 MeV, 0.5 mA) and a subcritical blanket thermal-power assembly 100 kW, are discussed. The main equipment is already available or is being built in industry. The setup can be used to investigate the dynamics of the interaction of a linac–driver and a subcritical reactor and problems concerning the accelerator–driver and the target–blanket assembly. The proton beams and neutron fluxes will be used for applied purposes. In the future it will be possible to increase substantially the current and energy of the proton beam. 相似文献
120.
We discuss specific features of Te-based compounds that made them the best materials for the phase-change data storage. It is demonstrated that the phase-change recording is due to a switch of Ge atoms between octahedral and tetrahedral symmetry positions within the Te face-centered cubic lattice. It is this nature of the transition that makes the Te-based media fast and stable. The driving force for this transition is also discussed. The chapter is concluded by introduction of a concept of the super-resolution near-field structure (super-RENS) disc that allows to reduce a bit size well below the diffraction limit and makes 100 GB/disc storage a reality. 相似文献