全文获取类型
收费全文 | 170135篇 |
免费 | 1327篇 |
国内免费 | 203篇 |
专业分类
电工技术 | 2574篇 |
综合类 | 122篇 |
化学工业 | 26945篇 |
金属工艺 | 9536篇 |
机械仪表 | 5744篇 |
建筑科学 | 3033篇 |
矿业工程 | 1891篇 |
能源动力 | 2741篇 |
轻工业 | 8863篇 |
水利工程 | 2734篇 |
石油天然气 | 8697篇 |
武器工业 | 12篇 |
无线电 | 14757篇 |
一般工业技术 | 38725篇 |
冶金工业 | 28010篇 |
原子能技术 | 6946篇 |
自动化技术 | 10335篇 |
出版年
2018年 | 3028篇 |
2017年 | 3148篇 |
2016年 | 3401篇 |
2015年 | 1709篇 |
2014年 | 3009篇 |
2013年 | 6431篇 |
2012年 | 4372篇 |
2011年 | 5467篇 |
2010年 | 4481篇 |
2009年 | 4962篇 |
2008年 | 4998篇 |
2007年 | 4931篇 |
2006年 | 4186篇 |
2005年 | 3849篇 |
2004年 | 3675篇 |
2003年 | 3567篇 |
2002年 | 3495篇 |
2001年 | 3492篇 |
2000年 | 3390篇 |
1999年 | 3244篇 |
1998年 | 7071篇 |
1997年 | 5180篇 |
1996年 | 3864篇 |
1995年 | 2948篇 |
1994年 | 2634篇 |
1993年 | 2750篇 |
1992年 | 2280篇 |
1991年 | 2325篇 |
1990年 | 2432篇 |
1989年 | 2330篇 |
1988年 | 2335篇 |
1987年 | 2211篇 |
1986年 | 2267篇 |
1985年 | 2317篇 |
1984年 | 2228篇 |
1983年 | 2152篇 |
1982年 | 1991篇 |
1981年 | 2207篇 |
1980年 | 2066篇 |
1979年 | 2281篇 |
1978年 | 2448篇 |
1977年 | 2450篇 |
1976年 | 3105篇 |
1975年 | 2249篇 |
1974年 | 2311篇 |
1973年 | 2349篇 |
1972年 | 2160篇 |
1971年 | 1912篇 |
1970年 | 1706篇 |
1969年 | 1634篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
Gina Cavaliere Giovanna Trinchese Nadia Musco Federico Infascelli Chiara De Filippo Vincenzo Mastellone Valeria Maria Morittu Pietro Lombardi Raffaella Tudisco Micaela Grossi Vincenzo Monda Monica I. Cutrignelli Antonietta Messina Serena Calabrò Heleena B. Moni Luigi Stradella Giovanni Messina Marcellino Monda Maria Pina Mollica 《Journal of dairy science》2018,101(3):1843-1851
Excessive energy intake may evoke complex biochemical processes characterized by inflammation, oxidative stress, and impairment of mitochondrial function that represent the main factors underlying noncommunicable diseases. Because cow milk is widely used for human nutrition and in food industry processing, the nutritional quality of milk is of special interest with respect to human health. In our study, we analyzed milk produced by dairy cows fed a diet characterized by a high forage:concentrate ratio (high forage milk, HFM). In view of the low n-6:n-3 ratio and high content of conjugated linoleic acid of HFM, we studied the effects of this milk on lipid metabolism, inflammation, mitochondrial function, and oxidative stress in a rat model. To this end, we supplemented for 4 wk the diet of male Wistar rats with HFM and with an isocaloric amount (82 kJ, 22 mL/d) of milk obtained from cows fed a diet with low forage:concentrate ratio, and analyzed the metabolic parameters of the animals. Our results indicate that HFM may positively affect lipid metabolism, leptin:adiponectin ratio, inflammation, mitochondrial function, and oxidative stress, providing the first evidence of the beneficial effects of HFM on rat metabolism. 相似文献
32.
Buryakov A. M. Khusyainov D. I. Mishina E. D. Khabibullin R. A. Yachmenev A. E. Ponomarev D. S. 《Technical Physics Letters》2018,44(12):1115-1119
Technical Physics Letters - The influence of excitation photons energy on the relaxation times of photoexcited carriers is studied. The involved relaxation mechanisms are evaluated and the... 相似文献
33.
34.
Verbovitskii Yu. V. Denis R. V. Shtender V. V. Zavalii I. Yu. 《Powder Metallurgy and Metal Ceramics》2015,54(3-4):220-226
Powder Metallurgy and Metal Ceramics - Multiphase La 2 MgNi 9 alloys are synthesized by induction melting. The crystalline structures of all phases in the alloys are determined with X-ray... 相似文献
35.
36.
A. V. Kozlov I. A. Portnykh V. I. Pastukhov 《The Physics of Metals and Metallography》2018,119(4):396-401
The influence of the temperature gradient over the thickness of the cladding of a fuel element of a fast-neutron reactor on the migration of point defects formed in the cladding material due to neutron irradiation has been studied. It has been shown that, under the action of the temperature gradient, the flux of vacancies onto the inner surface of the cladding is higher than the flux of interstitial atoms, which leads to the formation of a specific concentration profile in the cladding with a vacancy-depleted zone near the inner surface. The experimental results on the spatial distribution of pores over the cladding thickness have been presented with which the data on the concentration profiles and vacancy fluxes have been compared. 相似文献
37.
S. A. Pul’nev A. I. Pryadko A. V. Chikiryaka V. I. Nikolaev 《Technical Physics Letters》2018,44(11):992-994
The behavior of a superelastic Cu?14.2% Al?4%Ni single crystal in the case of high reversible strains under a longitudinal bending force was investigated. The effect of strain confinement along the crystal length was revealed and studied. The highest reversible strains (up to 10%) were shown to be confined within the central part of the bent crystal. 相似文献
38.
39.
L. S. Belevskii N. V. Koptseva I. V. Belevskaya Yu. Yu. Efimova 《Russian Metallurgy (Metally)》2015,2015(9):753-758
The microstructure and properties of the functional coatings formed by impact friction processing of product surfaces with a flexible tool are studied. It is established that the processing produces a hard nanostructured surface layer with fragments up to 0.13 µm in size, as it is achieved by severe plastic deformation. 相似文献
40.
D. A. Kudryashov A. S. Gudovskikh A. M. Mozharov A. D. Bol’shakov I. S. Mukhin Zh. I. Alferov 《Technical Physics Letters》2015,41(12):1120-1123
Design and operation modes of double-junction monolithic lattice-matched solar cells based on the ZnSiP2/Si system of materials have been calculated. The effect of the photoactive region thickness and minority carrier lifetime in ZnSiP2 layers on the efficiency of conversion of the incident solar light energy into electrical power was determined. It is shown that solar cells based on ZnSiP2/Si heterostructures can provide efficiencies of 28.8% at AM1.5D, 100 mW/cm2, and 33.3% at AM1.5D, 200 W/cm2. 相似文献