全文获取类型
收费全文 | 914篇 |
免费 | 3篇 |
专业分类
电工技术 | 21篇 |
化学工业 | 82篇 |
金属工艺 | 24篇 |
机械仪表 | 63篇 |
建筑科学 | 4篇 |
矿业工程 | 3篇 |
能源动力 | 6篇 |
轻工业 | 2篇 |
水利工程 | 16篇 |
石油天然气 | 55篇 |
无线电 | 60篇 |
一般工业技术 | 230篇 |
冶金工业 | 222篇 |
原子能技术 | 77篇 |
自动化技术 | 52篇 |
出版年
2021年 | 9篇 |
2020年 | 6篇 |
2019年 | 17篇 |
2018年 | 17篇 |
2017年 | 16篇 |
2016年 | 31篇 |
2015年 | 10篇 |
2014年 | 23篇 |
2013年 | 31篇 |
2012年 | 19篇 |
2011年 | 23篇 |
2010年 | 18篇 |
2009年 | 24篇 |
2008年 | 21篇 |
2007年 | 25篇 |
2006年 | 29篇 |
2005年 | 18篇 |
2004年 | 18篇 |
2003年 | 22篇 |
2002年 | 17篇 |
2001年 | 22篇 |
2000年 | 19篇 |
1999年 | 13篇 |
1998年 | 49篇 |
1997年 | 39篇 |
1996年 | 25篇 |
1995年 | 22篇 |
1994年 | 18篇 |
1993年 | 17篇 |
1991年 | 12篇 |
1989年 | 6篇 |
1988年 | 9篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1981年 | 12篇 |
1980年 | 11篇 |
1979年 | 13篇 |
1978年 | 12篇 |
1977年 | 24篇 |
1976年 | 41篇 |
1975年 | 18篇 |
1974年 | 12篇 |
1973年 | 13篇 |
1972年 | 8篇 |
1971年 | 11篇 |
1970年 | 7篇 |
1968年 | 6篇 |
1966年 | 9篇 |
排序方式: 共有917条查询结果,搜索用时 376 毫秒
71.
The effects of dry friction on a spherical pendulum are considered. Equations are derived for the angular velocity of the
rotation for the plane of oscillation. The behavior of a pendulum in the initial stage is examined in the linear approximation.
Translated from Izmeritel'naya Tekhnika, No. 6, pp. 3–5, June, 1998. 相似文献
72.
MV Zhernovo? SV Lebedev AA Grigoriuk IuA Krasnikov PV Kharitonski? 《Canadian Metallurgical Quarterly》1998,40(7):676-681
The influence of a constant magnetic field (strain 40 kA/m) on retina pigmentary cells of grass frog (Rana temporaria) and grey pigeon (Columba livia) eyes was investigated. Changes in the number and length of melanocytes appendixes were noticed accompanied by formation of thickenings in which melanosomes sized from 0.1 to 0.5 micron are moving. It is established that magnetic properties of eye retina pigmentary cells depend on the presence of Fe3+ in melanin. A theoretical model of paramagnetic receptor has been elaborated, according to which the induction of a magnetic field, formed by melanocyte, makes of the order 100 pT1. This value well compares with the size of magnetic field of a nervous impulse (120 pT1), extending throughout a nervous fibre of the frog sciatic nerve (Wikswo et al., 1980). This allows to suggest a possible unsynaptic way of transferring the information about the perceived magnetic field. 相似文献
73.
A history of the creation and development of the journal is presented for the period beginning in 1932. The thematics of the
journal is outlined, and its international status and heavy scientific leaning of published materials are noted.
__________
Translated from Khimicheskoe i Neftegazovoe Mashinostroenie, No. 7, pp. 3–5, July, 2007. 相似文献
74.
Vladimir Zaitsev Veniamin Nazarov Vitaly Gusev Bernard Castagnede 《NDT & E International》2006,39(3):184-194
Novel nonlinear-modulation methods for crack detection are discussed. The approach is based on the so-called cross-modulation effect consisting of the modulation transfer from an intensive, initially slowly amplitude-modulated stronger (pump) excitation to the probe signal. Advantage of this technique is a very flexible choice of the operation frequencies, since their ratio for both carriers and the modulation may be rather arbitrary. This in its turn allows one to effectively use the sample resonances in order to achieve the necessary level of the pump excitation and to ameliorate conditions for detection of the modulation sidelobes for the probe wave. Unlike higher harmonic-generation methods the initial nonlinear distortions of the pump and probe excitations (e.g. due to nonlinearities in the electronics) are not critical for this technique. In the paper we summarise results of recent test experiments that indicated high sensitivity of the new technique. 相似文献
75.
An amplitude algorithm is considered for detecting weak and rare gravitational pulses in the minimum mode regime on a background of arbitrary additive non-Gaussian noise under conditions of parametric a priori uncertainty. 相似文献
76.
P. G. Baranov B. Ya. Ber O. N. Godisov I. V. Il’in A. N. Ionov A. K. Kaliteevskiĭ M. A. Kaliteevskiĭ I. M. Lazebnik A. Yu. Safronov H. -J. Pohl H. Riemann N. V. Abrosimov P. S. Kop’ev A. D. Bulanov A. V. Gusev 《Semiconductors》2006,40(8):901-910
Electron spin resonance (ESR) is used to study the neutron transmutation doping of silicon crystals enriched with 30Si isotope: phosphorus donors and radiation defects produced in the course of transmutational doping are observed. The ESR signals related to the phosphorus uncontrolled impurity in 30Si before transmutational doping (the P concentration is ~1015 cm?3) and phosphorus introduced by neutron irradiation with doses ~1 × 1019 cm?2 and ~1 × 1020 cm?2 (the P concentrations are ~5 × 1016 and ~7 × 1017 cm?3, respectively) are studied. As a result of drastic narrowing of the phosphorus ESR lines in 30Si, the intensity of lines increased appreciably, which made it possible to measure the phosphorus concentration in the samples with a small volume (down to 10?6 mm?3). The methods for determining the concentration of P donors from hyperfine structure in the ESR spectra of isolated P atoms, exchange-related pairs, and clusters that consist of three, four, and more P donors are developed. In the region of high concentrations of P donors, in which case the hyperfine structure disappears, the concentration of P donors was estimated from the exchange-narrowed ESR line. 相似文献
77.
Narayanan V. Maitra K. Linder B.P. Paruchuri V.K. Gusev E.P. Jamison P. Frank M.M. Steen M.L. La Tulipe D. Arnold J. Carruthers R. Lacey D.L. Cartier E. 《Electron Device Letters, IEEE》2006,27(7):591-594
The performance of aggressively scaled (1.4nm相似文献
78.
Ultrafast generation of acoustic waves in copper 总被引:1,自引:0,他引:1
Wright O.B. Gusev V.E. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1995,42(3):331-338
The ultrafast generation of acoustic waves in copper films is investigated with a femtosecond optical pump and probe technique. By studying the generation at times before the electrons and the lattice come into equilibrium, the strength of their interaction can be measured and the dynamics of ultrafast electron diffusion can be studied. The acoustic strain pulses observed are bipolar in shape with exponential tails that are much broader than expected from simple thermoelastic stress generation. This can be explained by the supersonic diffusion of electrons over distances larger than the optical skin depth. The nonequilibrium diffusion equations governing stress generation are nonlinear, and are solved numerically. Using a linearized formulation, we also solve them analytically to a good approximation. The acoustic strain profile provides a `snapshot' of the initial spatial temperature distribution of the lattice, thus allowing a sensitive probe of the nonequilibrium dynamics of the diffusion. The electron-phonon coupling constant can be estimated directly from the acoustic pulse duration, provided that the sound velocity and thermal conductivity are known. In general, the relaxation and diffusion of carriers is specific to the sample in question, whether metal or semiconductor, suggesting the use of this method for thin film characterization 相似文献
79.
In this paper, the frequency characteristic of loudspeaker-driven thermoacoustic refrigerator (TAR) and the influence factors were investigated theoretically and experimentally. Experimental results under different conditions show that a narrow transmission frequency band of TAR exists to generate strong oscillation and cause significant thermoacoustic effect, and TAR achieves optimum performance at the resonance frequency. The frequency characteristic is determined by combined network elements of TAR. Then the analytical model was built to validate the experimental results. It provides a coupling method for design of loudspeaker-driven TAR system. 相似文献
80.
T. P. Aleksandrova A. A. Vais A. I. Masliy V. A. Burmistrov A. A. Gusev S. K. Bagavieva 《Materials and Manufacturing Processes》2015,30(6):798-803
Chemical and electrochemical methods to deposit nanolayers of metallic silver and its low-solubility compounds on polymer fiber surfaces are presented. The morphology and phase composition of the coatings were studied and their antimicrobial activity compared. We find that the antimicrobial activity of the coatings increases substantially with increasing solubility. Their high surface area and high porosity make synthetic fibers with these coatings promising for application as antimicrobial filters in air purification and water treatment systems. 相似文献