全文获取类型
收费全文 | 986篇 |
免费 | 1篇 |
国内免费 | 3篇 |
学科分类
工业技术 | 990篇 |
出版年
2021年 | 15篇 |
2019年 | 13篇 |
2018年 | 23篇 |
2017年 | 22篇 |
2016年 | 23篇 |
2015年 | 15篇 |
2014年 | 30篇 |
2013年 | 39篇 |
2012年 | 34篇 |
2011年 | 21篇 |
2010年 | 29篇 |
2009年 | 20篇 |
2008年 | 31篇 |
2007年 | 35篇 |
2006年 | 26篇 |
2005年 | 20篇 |
2004年 | 24篇 |
2003年 | 19篇 |
2002年 | 21篇 |
2001年 | 16篇 |
2000年 | 18篇 |
1998年 | 22篇 |
1997年 | 26篇 |
1996年 | 20篇 |
1995年 | 14篇 |
1994年 | 11篇 |
1993年 | 12篇 |
1992年 | 11篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 11篇 |
1986年 | 13篇 |
1985年 | 11篇 |
1984年 | 12篇 |
1983年 | 16篇 |
1982年 | 11篇 |
1981年 | 15篇 |
1980年 | 16篇 |
1979年 | 11篇 |
1978年 | 16篇 |
1977年 | 15篇 |
1976年 | 22篇 |
1975年 | 18篇 |
1974年 | 14篇 |
1973年 | 17篇 |
1972年 | 14篇 |
1971年 | 10篇 |
1970年 | 16篇 |
1968年 | 14篇 |
1966年 | 12篇 |
排序方式: 共有990条查询结果,搜索用时 254 毫秒
51.
Kinetics of electrons occupying two subbands in a quantum well in the presence of a high in-plane accelerating electric field
is studied taking into account optical-and acoustic-phonon scattering and scattering via resonance quasi-stationary states
associated with shallow donors. Resonance scattering is analyzed in the context of the well-known Breit–Wigner model. The
distribution function is constructed using the “random-walk” Monte Carlo method. Resonance-state scattering leads to the accumulation
of electrons in the vicinity of the resonance state and, in general, to a considerable modification of the streaming-regime
distribution function. The dependence of relative occupancies of the two subbands on the lattice temperature is determined. 相似文献
52.
The dependence of the magnetic characteristics of permalloy nanostructures on their sizes has been studied by the micromagnetic simulation method. The critical size of a square-shaped nanoisland for transition into a single-domain state has been estimated. The dependence of the coercive force of the nanoisland on its thickness and area has been studied. 相似文献
53.
Si-Hyung Lee Ju-Hyung Kim Jeon-Kook Lee G. D. Mansfeld S. G. Alekseev Ki Hyun Yoon 《组合铁电体》2013,141(1-4):155-166
Abstract Using the composite resonator with additional thick AlN film with the FWHM of rocking curve of 2.53° under investigation, the bulk acoustic wave attenuation constant and sound velocity along c-axis were directly measured. The method of High Overtone Bulk acoustic wave Resonator (HBAR) spectroscopy based on frequency, measurements of the positions of the resonator peculiarities of phase and amplitude of electromagnetic wave reflection coefficient from composite resonator structure was applied. The method provides attenuation and velocity measurement in a wide frequency band, using the same sample. For the measurements, standard and modified HBAR spectroscopy based on the analysis of only parallel resonance properties of composite resonator structures were used. 相似文献
54.
A. K. Alekseev 《Journal of Engineering Physics and Thermophysics》2002,75(2):446-452
Consideration has been given to the employment of the conjugate problems of first and second orders, which are applied to solution of the inverse problems of heat exchange, to calculate the error of solution of the primal problem from the data on the error of the initial information. It has been shown that the algorithms of solution of the inverse problems of heat exchange in a variational formulation make it possible to directly determine the error of the corresponding primal problems by calculation of the Hessian range. 相似文献
55.
P. A. Platonov Ya. I. Shtrombakh O. K. Chugunov N. S. Lobanov V. P. Aleksandrov V. M. Alekseev V. M. Semochkin V. A. Denisov V. N. Kochkin 《Atomic Energy》2002,92(6):475-481
The immobilization of radionuclides in samples of GR-280 reactor graphite by the fixative atomik is described. A graphite block extracted from RBMK masonry after 17 years of operation is used for the investigations.The investigations showed that the strength of the fixative samples increases only with irradiation doses above 15000 Mrad. The radiation–chemical yield of gaseous products of radiolysis from samples of the fixative under irradiation in vacuum is 12·10–10 cm3/(g·rad). , , and -emitting nuclides are leached from the samples of irradiated graphite; this process proceeds continually. When the irradiated graphite samples are permeated with the fixative atomik, no release of radionuclides is observed at 20°C for 2 yr. 相似文献
56.
G. A. Filippov E. I. Grishanin L. N. Fal’kovskii B. I. Fonarev P. N. Alekseev N. E. Kukharkin P. A. Fomichenko V. F. Tsibul’skii A. V. Chibinyaev 《Atomic Energy》2006,100(3):192-198
A system of new technical solutions, which will make it possible to develop a reactor system using a coolant with supercritical
parameters and efficiency 44%, solving the main problems of the nonuniformity of coolant heating in the core, is examined.
This sytem contains a core based on fuel micropellets, a multistep fuel assembly with transverse coolant flow, coolant mixing
after each step, and continual reloading of fuel micropellets into each fuel assembly.
__________
Translated from Atomnaya énergiya, Vol. 100, No. 3, pp. 197–204, March, 2006. 相似文献
57.
AA Zargarov II Senin AM Alekseev SV Shul''ga-Morsko? PP Filippov VM Lipkin 《Canadian Metallurgical Quarterly》1996,22(7):483-488
Numerous data strongly suggest the involvement of cytokines and the matrix metalloproteinase collagenase (MMP-1) in the pathogenesis of periodontitis. Recently, we have demonstrated that, upon culturing under the influence of IL-1 alpha + EGF, a large amount of inactive procollagenase (MMP-1) is stored in the extracellular matrix of periosteal tissue. We now show that this endogenous reservoir of proenzyme can be operative after activation with plasmin and is able to induce a rapid and almost complete breakdown of the collagenous extracellular matrix. The level of collagen degradation following activation showed a strong correlation with the amount of proenzyme that was incorporated in the tissue. The highest level of degradation (70% of the total amount of collagenous proteins) was found with the IL-1 alpha + EGF-treated explants, followed by those treated with IL-1 alpha alone (35%). Explants cultured with EGF or in the absence of cytokines, containing only small amounts of procollagenase, showed little collagen breakdown following plasmin activation (7%). Inhibition of metalloproteinases by EDTA, or blockage of plasmin by PMSF, prevented the degradation in all explants irrespective of the amount of proenzyme present in the tissue. Our findings demonstrate that endogenous proenzyme stored in a native connective tissue matrix can be activated at a later time interval which results in a massive breakdown of the tissue. This study shows a possible pathway of collagenase-induced breakdown without recent de novo synthesis of the enzyme. Such a sequence may be operative in chronic inflammatory diseases, such as periodontitis, where production of procollagenase under the influence of cytokines spans a longer time period, whereas breakdown is often characterized by a cyclic behaviour. 相似文献
58.
59.
60.