全文获取类型
收费全文 | 93271篇 |
免费 | 1557篇 |
国内免费 | 733篇 |
专业分类
电工技术 | 1661篇 |
综合类 | 71篇 |
化学工业 | 14859篇 |
金属工艺 | 3900篇 |
机械仪表 | 3028篇 |
建筑科学 | 2572篇 |
矿业工程 | 610篇 |
能源动力 | 2438篇 |
轻工业 | 7991篇 |
水利工程 | 1012篇 |
石油天然气 | 2371篇 |
武器工业 | 41篇 |
无线电 | 8628篇 |
一般工业技术 | 19736篇 |
冶金工业 | 15788篇 |
原子能技术 | 2739篇 |
自动化技术 | 8116篇 |
出版年
2022年 | 779篇 |
2021年 | 1223篇 |
2020年 | 928篇 |
2019年 | 1043篇 |
2018年 | 1912篇 |
2017年 | 1934篇 |
2016年 | 2165篇 |
2015年 | 1275篇 |
2014年 | 2062篇 |
2013年 | 4762篇 |
2012年 | 3163篇 |
2011年 | 3968篇 |
2010年 | 3149篇 |
2009年 | 3461篇 |
2008年 | 3537篇 |
2007年 | 3412篇 |
2006年 | 2927篇 |
2005年 | 2634篇 |
2004年 | 2425篇 |
2003年 | 2318篇 |
2002年 | 2224篇 |
2001年 | 2004篇 |
2000年 | 1969篇 |
1999年 | 1885篇 |
1998年 | 4009篇 |
1997年 | 2889篇 |
1996年 | 2255篇 |
1995年 | 1817篇 |
1994年 | 1610篇 |
1993年 | 1608篇 |
1992年 | 1253篇 |
1991年 | 1209篇 |
1990年 | 1299篇 |
1989年 | 1253篇 |
1988年 | 1106篇 |
1987年 | 1039篇 |
1986年 | 1033篇 |
1985年 | 1116篇 |
1984年 | 973篇 |
1983年 | 926篇 |
1982年 | 842篇 |
1981年 | 856篇 |
1980年 | 804篇 |
1979年 | 811篇 |
1978年 | 742篇 |
1977年 | 894篇 |
1976年 | 1092篇 |
1975年 | 702篇 |
1974年 | 657篇 |
1973年 | 651篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
V. V. Andreev A. V. Kedrov B. G. Levakov O. A. Mingazov S. G. Porubov S. V. Shugaev 《Atomic Energy》2007,102(3):174-180
The results of investigations of the operation of the IGRIK pulsed homogeneous solution research complex in the unconventional
(for pulsed reactors) two-pulse mode with successive reactivity increments with generation of prompt-or delayed-neutron pulses
are presented. Experimental data which give an idea of the processes occurring in the reactor core in the two-pulse regime
are obtained. These data made it possible to determine whether or not the IGRIK reactor can be operated in this regime and
the limitations imposed by the physical processes and special design characteristics of the system.
It is shown that are pulses can be generated in several different ways. The dependences of the fission-pulse characteristics
in a given regime on the initial conditions and the methods for obtaining the pulses are investigated. Methods are proposed
for increasing the operational possibilities of the reactor.
__________
Translated from Atomnaya énergiya, Vol. 102, No. 3, pp. 146–151, March, 2007. 相似文献
992.
A. Ya. Fridman E. M. Morozova A. Yu. Tsivadze N. P. Sokolova I. I. Bardyshev A. M. Gorbunov O. P. Shapokhina 《Protection of Metals》2007,43(5):454-458
With the aim of classifying PVC materials in which surface layers are converted into interpenetrated network cyclam nanofilms
among polymer-polymer systems, comparative studies of their properties were carried out with consideration for the specific
conditions for the preparation of the material. The density and structures of near-surface layers, the bulk ratio of the ordered
and disordered forms, the dynamics of swelling in water, and the effective partial volume occupied by water molecules were
studied for PVC plates prior to and after hydrothermal treatment. The conversion of the surface layers changes the structural
self-organization of PVC: the polymer structure becomes more compact and ordered both in the area adjacent to the nanofilm
and in the polymer bulk, which is characteristic of systems of the type “hard coating on soft substrate”.
Original Russian Text ? A.Ya. Fridman, E.M. Morozova, A.Yu. Tsivadze, N.P. Sokolova, I.I. Bardyshev, A.M. Gorbunov, O.P. Shapokhina,
2007, published in Zashchita Metallov, 2007, Vol. 43, No. 5, pp. 498–502. 相似文献
993.
David P. Cormode Jason J. Davis Paul D. Beer 《Journal of Inorganic and Organometallic Polymers and Materials》2008,18(1):32-40
Disulfide and dithiocarbamate functionalized porphyrins have been synthesized and used as protecting ligands for gold nanoparticle
formation either via ligand substitution reactions or by direct synthesis. These nanoparticles have been shown to recognize
anions via changes in the absorbance spectrum of the surface adsorbed porphyrin moieties. Association constants, derived from
quantitative titrations, indicate a remarkable surface enhancement effect where the surface bound porphyrins bind anions much
more strongly than the free receptor in solution. 相似文献
994.
995.
996.
J.C. Arnault S. Saada M. Nesladek O.A. Williams K. Haenen P. Bergonzo E. Osawa 《Diamond and Related Materials》2008,17(7-10):1143-1149
Detonation nanodiamond dispersed on silicon surfaces underwent different H2 MPCVD exposures. The induced changes at the surface have been characterized in situ by XPS and XEELS. Then, a short CH4/H2 growth step was applied. This sequential study revealed an excellent stability of detonation nanodiamond. The sp3 etching rate is insufficient to remove nanodiamond even under intense H2 plasma. The H2 exposure could be successfully used to remove C–C sp2 carbon without altering sp3 seeds. Moreover, the formation of silicon carbide observed after the hydrogen treatment is thought to be helpful to enhance the adhesion of nanodiamond particles on the substrate. 相似文献
997.
Yodel: A Yield Stress Model for Suspensions 总被引:1,自引:0,他引:1
A model for the yield stress of particulate suspensions is presented that incorporates microstructural parameters taking into account volume fraction of solids, particle size, particle size distribution, maximum packing, percolation threshold, and interparticle forces. The model relates the interparticle forces between particles of dissimilar size and the statistical distribution of particle pairs expected for measured or log-normal size distributions. The model is tested on published data of sub-micron ceramic suspensions and represents the measured data very well, over a wide range of volume fractions of solids. The model shows the variation of the yield stress of particulate suspensions to be inversely proportional to the particle diameter. Not all the parameters in the model could be directly evaluated; thus, two were used as adjustable variables: the maximum packing fraction and the minimum interparticle separation distance. The values for these two adjustable variables provided by the model are in good agreement with separate determinations of these parameters. This indicates that the model and the approximations used in its derivation capture the main parameters that influence the yield stress of particulate suspensions and should help us to better predict changes in the rheological properties of complex suspensions. The model predicts the variation of the yield stress of particulate suspensions to be inversely proportional to the particle diameter, but the experimental results do not show a clear dependence on diameter. This result is consistent with previous evaluations, which have shown significant variations in this dependence, and the reasons behind the yield stress dependence on particle size are discussed in the context of the radius of curvature of particles at contact. 相似文献
998.
A new scheme for bidirectional WDM-PON using upstream and downstream channels generated by optical carrier suppression and separation technique 总被引:1,自引:0,他引:1
O. Akanbi Jianjun Yu Gee-Kung Chang 《Photonics Technology Letters, IEEE》2006,18(2):340-342
We propose a new bidirectional dense wavelength-division-multiplexing (DWDM)-based passive optical network using optical carrier suppression and separation technique to generate both upstream and downstream wavelength channels from a single laser. Thirty-two DWDM channels have been generated, and symmetric 10-Gb/s data transmission of a wavelength pair has been demonstrated. 相似文献
999.
1000.
N. T. Gurin A. V. Shlyapin O. Yu. Sabitov D. V. Ryabov 《Technical Physics Letters》2003,29(2):134-137
Significant distinctions have been observed in the current kinetics and current-voltage characteristics of ZnS: Mn electroluminescent
thin-film emitters measured with pulsed photoexcitation in different (blue, red, and infrared) spectral intervals. The results
show evidence that a recharge of deep centers related to the zinc and sulfur vacancies takes place in the course of the emitter
operation, leading to the formation of space charges in the near-anode and near-cathode regions of the phosphor layer. 相似文献