全文获取类型
收费全文 | 4247篇 |
免费 | 33篇 |
国内免费 | 8篇 |
学科分类
工业技术 | 4288篇 |
出版年
2021年 | 70篇 |
2020年 | 46篇 |
2019年 | 54篇 |
2018年 | 129篇 |
2017年 | 135篇 |
2016年 | 174篇 |
2015年 | 64篇 |
2014年 | 100篇 |
2013年 | 150篇 |
2012年 | 145篇 |
2011年 | 164篇 |
2010年 | 137篇 |
2009年 | 161篇 |
2008年 | 150篇 |
2007年 | 143篇 |
2006年 | 107篇 |
2005年 | 101篇 |
2004年 | 79篇 |
2003年 | 80篇 |
2002年 | 82篇 |
2001年 | 70篇 |
2000年 | 74篇 |
1999年 | 71篇 |
1998年 | 97篇 |
1997年 | 74篇 |
1996年 | 69篇 |
1995年 | 74篇 |
1994年 | 47篇 |
1993年 | 59篇 |
1992年 | 42篇 |
1991年 | 51篇 |
1990年 | 50篇 |
1989年 | 48篇 |
1986年 | 45篇 |
1984年 | 50篇 |
1983年 | 54篇 |
1982年 | 49篇 |
1981年 | 55篇 |
1980年 | 43篇 |
1979年 | 47篇 |
1978年 | 73篇 |
1977年 | 66篇 |
1976年 | 80篇 |
1975年 | 53篇 |
1974年 | 52篇 |
1973年 | 47篇 |
1972年 | 44篇 |
1971年 | 41篇 |
1969年 | 38篇 |
1968年 | 37篇 |
排序方式: 共有4288条查询结果,搜索用时 15 毫秒
71.
V. G. Ivanov M. D. Timofeev Z. I. Solov'eva 《Power Technology and Engineering (formerly Hydrotechnical Construction)》1988,22(7):446-449
1. |
Borehole bench marks I–VI practically work just as the settlement marks of the dam and surface cliff bench marks located near the dam.
Consequently, with such a scheme of embedding the bench marks it was not possible to fall outside the zone of formation of settlement, and the given borehole bench marks cannot serve as a reliable, independent reference for determining dam settlements. 相似文献
72.
Conclusions The insertion of an additional accelerating system with multiplicity nq is desirable only in a synchrotron with a well-bunched beam, where the natural nonlinearity A
0
2
is small.When the amplitude of the additional voltage is limited by the quantity nVn/Vo1, there are two approximately equivalent schemes for switching on the harmonics nq (see Secs. 3 and 4), which permit obtaining an instability suppression factor of max10/A
o
2
with nopt5/Ao.The efficiency of both schemes has been confirmed experimentally in ISR storage rings [1, 5], but there are no data for making quantitative comparisons of the experimental results with our calculations. At the same time switching on the harmonic n=2 in the PSB synchrotron without satisfying the condition (39) only increased the longitudinal instability of the beam [6].By raising significantly the amplitude of the additional voltage in the state of Sec. 3, which is equivalent to transferring to an acceleration multiplicity nq while keeping constant the number of bunches, it is possible to raise the instability suppression factor to max 5/A
o
2
with nopt2.3/Ao[nVn/Vo]1/4.Translated from Atomnaya Énergiya, Vol. 62, No. 2, pp. 98–104, February, 1987. 相似文献
73.
V. V. Goncharov K. P. Dubrovin E. G. Ivanov V. T. Korneev A. B. Kruglov L. M. Lebedev 《Atomic Energy》1987,62(5):356-363
Conclusions In an MR reactor performance tests of 16 fuel assemblies, with elements having essentially the same structure as standard VVÉR-100 fuel elements, were carried out. Tests of five more fuel assemblies are continuing. Of the 16 assemblies, 13 were studied in a hot laboratory.The tests in the MR, carried out at high loads and with a large number of transition processes, as well as the postreactor studies, indicated that fuel elements of the specified design (with initial helium pressures of 1.96–2.45 MPa) have a high reliability. None of the elements of the fuel assemblies studied malfunctioned due to design defects or faults in their fabrication. During the tests the jackets were subject to a little oxidation and hydrogenation (zirconium-oxide film<3 m thick, hydrogen content less than 0.008% by mass), and their plasticity remained high (the relative elongation at the working temperature remained at the 20% level).Translated from Atomnaya Énergiya, Vol. 62, No. 5, pp. 312–317, May, 1987. 相似文献
74.
75.
Yu. P. Ivanov A. V. Ognev L. A. Chebotkevich 《The Physics of Metals and Metallography》2006,101(5):450-455
The magnetic anisotropy of Co/Cu/Co films with the thickness of the copper spacer corresponding to the antiferromagnetic and ferromagnetic indirect exchange coupling between Co layers has been studied. The films deposited on naturally oxidized (111) Si single crystals were produced by magnetron sputtering. The films were annealed at 240°C. Such an annealing virtually neither changes the grain size nor leads to the mixing of layers; i.e., no disturbance of the coupling type between the cobalt layers takes place. Changes in the surface and induced magnetic anisotropy and in the effective energy of indirect exchange coupling have been studied upon annealing in the presence and absence of a magnetic field. It has been found that the shape of surface inhomogeneities in the films changes upon annealing in the magnetic field applied along the film plane, which substantially affects, the surface anisotropy. In the films characterized by antiferromagnetic coupling, the easy axis of magnetization is induced only in the magnetic fields exceeding the saturation field. The induced-anisotropy constant estimated theoretically agrees well with those determined experimentally. 相似文献
76.
77.
G. Petkova E. Sokolova S. Raicheva P. Ivanov 《Journal of Applied Electrochemistry》1998,28(10):1067-1071
The inhibition effect of gamma-pyrodiphenone (PD) on copper corrosion in near neutral sulphate solutions was investigated. Weight loss and polarization measurements show a high inhibition efficiency (>96%) of PD on copper corrosion at extremely low concentrations. PD suppresses active copper dissolution and oxygen reduction. The potentiodynamic cathodic reduction measurements showed an inhibition of oxide formation and stabilization of the Cu2O oxide in the presence of PD. XPS measurements suggested that the high inhibition effect of PD on copper corrosion is due to the adsorption of PD molecules, as a first stage, and the formation of a film with a polymer-like structure by coordination of PD with Cu2O on prolonged exposure. 相似文献
78.
L. C. Feng W. Z. Shao L. Zhen N. Xie V. V. Ivanov 《International Journal of Applied Ceramic Technology》2007,4(5):453-462
Cu
79.
A. G. Fedorenko M. A. Syrunin A. G. Ivanov 《Combustion, Explosion, and Shock Waves》2005,41(5):487-495
Experimental data on the dynamic response and strength of simple shells of fiber composites are used to justify the choice
of these materials for the load-bearing shells of blast-proof structures. It is shown that in such structures composites are
preferred to homogeneous metal alloys (structural steels) to eliminate strong scale effects of an energetic nature. A criterion
for selecting fibers is proposed and justified experimentally, and reinforcement patterns are determined to obtain optimal
(in the strength-mass ratio) compositions for the load-bearing shells of blast-proof containers and chambers.
__________
Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 5, pp. 3–13, September–October, 2005. 相似文献
80.
The morphological and hydrodynamic properties of a series of homogeneous fractions of substituted poly(methylmethacrylate) (A units) bearing keto-β-functional groups (B units) of the general structureCOCH2R, with R = SOxCH3 (x = 1,2) or SO2N(CH3)2, were investigated by intrinsic viscosity, light scattering and partial specific volume measurements in dimethylformamide (DMF) solution at 25°C. For molar substitution degrees , the copolymers behave as flexible random coils. The Stockmayer-Fixman-Yamakawa analysis of the data leads to slightly higher unperturbed dimensions Ko and steric factor σ than those for PMMA, and to stronger chain expansion as a result of the weak hydrogen bonding between DMF and COCH2R units and a positive XAB interaction parameter. For however, copolymers bearing COCH2SO2N(CH3)2 groups behave as worm-like chains, as derived from the Fujii-Yamakawa analysis of the data: the persistence length increases from 380 to 570 Å within the m range 0.57–0.75. This transition from a random coil to a worm-like chain for was tentatively correlated with the accumulation of B units in sterically hindered and self-associated short blocks of average length lB ? 1.6 which provide drastically increased rigidity to the copolymer chain. 相似文献
|