全文获取类型
收费全文 | 5220篇 |
免费 | 87篇 |
国内免费 | 14篇 |
专业分类
电工技术 | 76篇 |
综合类 | 4篇 |
化学工业 | 1063篇 |
金属工艺 | 281篇 |
机械仪表 | 236篇 |
建筑科学 | 46篇 |
矿业工程 | 79篇 |
能源动力 | 66篇 |
轻工业 | 74篇 |
水利工程 | 72篇 |
石油天然气 | 210篇 |
武器工业 | 2篇 |
无线电 | 473篇 |
一般工业技术 | 1291篇 |
冶金工业 | 621篇 |
原子能技术 | 402篇 |
自动化技术 | 325篇 |
出版年
2022年 | 131篇 |
2021年 | 154篇 |
2020年 | 76篇 |
2019年 | 82篇 |
2018年 | 173篇 |
2017年 | 159篇 |
2016年 | 212篇 |
2015年 | 90篇 |
2014年 | 132篇 |
2013年 | 206篇 |
2012年 | 206篇 |
2011年 | 227篇 |
2010年 | 183篇 |
2009年 | 193篇 |
2008年 | 203篇 |
2007年 | 184篇 |
2006年 | 143篇 |
2005年 | 126篇 |
2004年 | 100篇 |
2003年 | 106篇 |
2002年 | 105篇 |
2001年 | 78篇 |
2000年 | 83篇 |
1999年 | 74篇 |
1998年 | 101篇 |
1997年 | 80篇 |
1996年 | 72篇 |
1995年 | 84篇 |
1994年 | 52篇 |
1993年 | 63篇 |
1992年 | 50篇 |
1991年 | 56篇 |
1990年 | 50篇 |
1989年 | 50篇 |
1986年 | 50篇 |
1984年 | 48篇 |
1983年 | 57篇 |
1982年 | 48篇 |
1981年 | 58篇 |
1980年 | 45篇 |
1979年 | 48篇 |
1978年 | 79篇 |
1977年 | 72篇 |
1976年 | 91篇 |
1975年 | 57篇 |
1974年 | 57篇 |
1973年 | 54篇 |
1972年 | 44篇 |
1971年 | 42篇 |
1969年 | 39篇 |
排序方式: 共有5321条查询结果,搜索用时 15 毫秒
51.
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
52.
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
53.
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
54.
55.
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
56.
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
57.
58.
Valerii S. Kozlov Elena P. Yausheva Svetlana A. Terpugova Mikhail V. Panchenko Dmitriy G. Chernov Vladimir P. Shmargunov 《International journal of remote sensing》2014,35(15):5722-5741
A comprehensive experiment on the study of dynamics of optical and microphysical characteristics of submicron aerosols in the near-ground air layer was carried out in June–August of 2012 under conditions of extremely strong smoke haze originating from vast forest fires in Siberia. Variations of the spectral angular scattering coefficients and the degree of linear polarization in the visible wavelength range are studied, as well as the mass concentrations of dry fractions of aerosol and black carbon, relative content of black carbon (BC fraction), single scattering albedo, particle size distribution function, complex refractive index of the particulate matter, and parameter of condensation activity of aerosol. Peculiarities of differences between optical and microphysical characteristics of near-ground aerosol in smoke haze and under smokeless conditions are revealed. This study is important for validation of results of remote sensing of the composition of smoke haze and background atmosphere obtained from satellite data and sun photometric measurements at the Aerosol Robotic Network (AERONET). 相似文献
59.
R. Sh. Mikhail R. I. A. Malek 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1971,21(10):277-282
Specific surface areas and pore size distribution analysis were taken as essential parameters to explore the microstructure of hardened gypsum pastes. The hydration of gypsum plaster is essentially affected by the water/plaster ratio of the mix, and by the presence of additives which might act as retarders or accelerators to the hydration process. Affecting the microstructure would mutually lead to variations of the compressive strength of the hardened pastes, and these variations are also discussed. Results are mainly expressed in terms of the solid (measured by the extent of its specific area) to the space (pore) ratios. Dual distribution of pore sizes was observed and the two groups of pores are designed as S (small) and L (large) pores. Similarities to the microstructure of hardened Portland cement pastes are indicated. Accelerators appear to function differently from retarders, and the effects of water/plaster ratios were investigated in both cases. The results obtained may carry many significant practical implications to the future use of hardened gypsum pastes. 相似文献
60.
Raouf Sh. Mikhail Suzy A. Selim Farouk I. Zeidan 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1976,26(4):191-198
The surface properties of a stannic oxide gel and its thermal dehydration products obtained both in vacuo and in the presence of air in the temperature range 100–600°C have been examined by N2 adsorption. Phase and structural changes have been followed by differential thermal analysis and X-ray diffractometry. Complete pore structure analysis showed that samples dehydrated at or below 250°C were microporous. Above 250°C the pores were found to widen with increase of temperature, the widening occurring concurrently with the crystallisation process. Doping with cations of lower valency (Li+ and Al3+) than the host cation (Sn4+) had little effect on the pore structure and specific surface area for the low temperature samples (≤250°), whereas at higher temperatures, e.g. 600°C, it increased the specific area remarkably. The dope ions produce oxygen vacancies and hinder or retard sintering in SnO2. 相似文献
|