全文获取类型
收费全文 | 524篇 |
免费 | 9篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 47篇 |
金属工艺 | 35篇 |
机械仪表 | 19篇 |
建筑科学 | 1篇 |
能源动力 | 9篇 |
水利工程 | 14篇 |
石油天然气 | 131篇 |
无线电 | 37篇 |
一般工业技术 | 137篇 |
冶金工业 | 44篇 |
原子能技术 | 6篇 |
自动化技术 | 50篇 |
出版年
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 7篇 |
2018年 | 9篇 |
2017年 | 12篇 |
2016年 | 15篇 |
2015年 | 6篇 |
2014年 | 11篇 |
2013年 | 13篇 |
2012年 | 14篇 |
2011年 | 31篇 |
2010年 | 13篇 |
2009年 | 14篇 |
2008年 | 22篇 |
2007年 | 16篇 |
2006年 | 7篇 |
2005年 | 9篇 |
2004年 | 18篇 |
2003年 | 18篇 |
2002年 | 12篇 |
2001年 | 10篇 |
2000年 | 15篇 |
1999年 | 9篇 |
1998年 | 10篇 |
1997年 | 12篇 |
1996年 | 11篇 |
1995年 | 7篇 |
1994年 | 11篇 |
1993年 | 16篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1987年 | 10篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 10篇 |
1976年 | 6篇 |
1975年 | 6篇 |
1974年 | 6篇 |
1973年 | 6篇 |
1972年 | 7篇 |
1971年 | 6篇 |
1970年 | 7篇 |
1968年 | 7篇 |
排序方式: 共有533条查询结果,搜索用时 0 毫秒
101.
ABSTRACT: : We report that porous silicon acoustic Bragg reflectors and AlN-based transducers can be successfully combined and processed in a commercial solidly mounted resonator production line. The resulting device takes advantage of the unique acoustic properties of porous silicon in order to form a monolithically integrated bulk acoustic wave resonator. 相似文献
102.
Results of studies of the conductivity σ and the Hall coefficient R in the Cd
x
Hg1 − x
Te crystals with x = 0.1, 0.12, 0.14, and 0.15 are analyzed in the temperature range T = 4.2–300 K and the magnetic field range B = 0.005–2.22 T. Using data on the R(B) in low and high magnetic fields and the data on σ(T), electron and hole concentrations and mobilities are determined. It is shown that the electron concentration n in the studied samples is almost independent of T in the range 4.2–15 K, while as T increases, it increases according to the law n ∝ T
r
(r > 3/2), where r = f(n, T, x). It is found that r varies from 1.7 at x = 0.1 to 3.1 at compositions with x = 0.14 and 0.15. The results for n(T) are compared with theory, taking into account nonparabolicity of the variance law for ⃛(T), and with the theory of impurity states in narrow-gap and zero-gap semiconductors. It is shown that the constancy of n(T) up to ∼15 K and the strong dependence n(T) (r > 3/2) at higher temperatures are caused by the intense ionization of electrons localized at acceptor states. 相似文献
103.
104.
Аlexey V. Vakhin Firdavs. A. Aliev Sergey I. Kudryashov Igor S. Afanasiev Oleg V. Petrashov Sergey A. Sitnov 《Petroleum Science and Technology》2013,31(21):1829-1836
AbstractThis paper is devoted to the study of aquathermolysis processes of heavy oil produced by CSS technology on Boca de Jaruco oil field. Various catalysts based on cobalt, nickel, iron and copper were used for intensification of in-situ upgrading processes of heavy oil. The first paper in series is presented results of transformation of crude oil and its saturate fraction after thermal treatment with and without catalysts by SARA analysis, MALDI mass-spectrometry, FTIR-spectroscopy and gas chromatography. It is revealed, that catalysts provide more deep conversion of asphaltenes and resins into lighter hydrocarbons. Particularly, for the given heavy oil, catalysts based on iron and nickel organic salts are more effective to reduce the content of high molecular weight components (asphaltenes). Saturates fraction after thermal treatment in presence of the catalysts is enriched with lighter alkanes in comparison to the crude oil treated without catalysts. Obtained results show that crude oil recovered by catalytic aquathermolysis processes will be better quality than the original oil in the place. 相似文献
105.
Summary
Radiation-induced graft polymerization of N,N-dimethylaminoethylmethacrylate (DMAEMA) from 50% solution in chloroform onto
poly(ethylene terephthalate) (PET) was carried out by means of mutual γ-irradiation of polymer in presence of liquid or vapor
phase monomer solutions (direct method), or by grafting of monomer from this liquid solution onto polymer preirradiated in
air. It has been shown higher effectiveness of grafting by the direct method from vapor phase of monomer or by the preirradiation
method as compared with direct grafting from liquid monomer solution. Grafting did not affect crystallinity, transparency
and durability of the starting PET.
Received: 18 November 1999/Revised version: 7 February 2000/Accepted: 8 February 2000 相似文献
106.
M. K. Kerimov M. A. Kurbanov A. A. Bayramov F. N. Tatardar G. Kh. Gulieva O. A. Aliev 《Surface Engineering and Applied Electrochemistry》2013,49(5):359-367
The pyroelectric properties of polymer-pyroceramic composites with components premodified under the action of a barrier discharge plasma and the pyroelectric properties of composites crystallized under the simultaneous action of a barrier discharge plasma and temperature are studied. It is shown that the plasma-assisted crystallization technology is more efficient for improving the pyroelectric properties of the composites. Plasma-assisted crystallization provides a high and stable pyroelectric state if the activation energy of the local levels formed in the quasi-bandgap of the polymer phase is higher than the deorientation energy of the domains of the pyrophase of the composite. 相似文献
107.
108.
109.
110.
A. M. Krokhmal'nyi A. G. Khanlarova I. N. Zin' Ya. M. Nagieva A. G. Aliev 《Materials Science》1989,25(3):329-331
Translated from Fiziko-Khimicheskaya Mekhanika Matrialov, Vol. 25, No. 3, pp. 101–102, May–June, 1989. 相似文献