全文获取类型
收费全文 | 412185篇 |
免费 | 4902篇 |
国内免费 | 2098篇 |
学科分类
工业技术 | 419185篇 |
出版年
2021年 | 1990篇 |
2020年 | 1505篇 |
2019年 | 1988篇 |
2018年 | 22708篇 |
2017年 | 22237篇 |
2016年 | 15714篇 |
2015年 | 3398篇 |
2014年 | 4320篇 |
2013年 | 12398篇 |
2012年 | 11538篇 |
2011年 | 24475篇 |
2010年 | 21325篇 |
2009年 | 19689篇 |
2008年 | 20712篇 |
2007年 | 23401篇 |
2006年 | 8938篇 |
2005年 | 12312篇 |
2004年 | 10465篇 |
2003年 | 9905篇 |
2002年 | 8079篇 |
2001年 | 7738篇 |
2000年 | 7309篇 |
1999年 | 7806篇 |
1998年 | 21809篇 |
1997年 | 14541篇 |
1996年 | 11394篇 |
1995年 | 8049篇 |
1994年 | 7070篇 |
1993年 | 6988篇 |
1992年 | 4659篇 |
1991年 | 4534篇 |
1990年 | 4377篇 |
1989年 | 4075篇 |
1988年 | 3718篇 |
1987年 | 2927篇 |
1986年 | 3019篇 |
1985年 | 3332篇 |
1984年 | 2948篇 |
1983年 | 2610篇 |
1982年 | 2444篇 |
1981年 | 2546篇 |
1980年 | 2229篇 |
1979年 | 2026篇 |
1978年 | 1971篇 |
1977年 | 2448篇 |
1976年 | 3446篇 |
1975年 | 1658篇 |
1974年 | 1585篇 |
1973年 | 1516篇 |
1972年 | 1260篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
51.
Akopdzhanyan T. G. Chemagina E. A. Borovinskaya I. P. 《Russian Journal of Non-Ferrous Metals》2020,61(6):686-690
Russian Journal of Non-Ferrous Metals - The synthesis and sintering of the (AlN)x(SiC)1 – x solid solution have been studied under conditions of self-propagating high-temperature synthesis... 相似文献
52.
Zavadiuk S.V. Loboda P.I. Soloviova T.O. Trosnikova I.Iu. Karasevska O.P. 《Powder Metallurgy and Metal Ceramics》2020,59(1-2):22-28
Powder Metallurgy and Metal Ceramics - The properties of sintered and heat-treated steels produced from the Catamold 8740 material by powder injection molding were examined. Parts made of the... 相似文献
53.
54.
Dr. Jiayao Y. Wang Dr. Jiaqi Q. Li Prof. Dr. Yumei M. Xiao Prof. Dr. Bin Fu Prof. Dr. Zhaohai H. Qin 《ChemMedChem》2020,15(5):404-410
Mitochondrial oxidative damage and dysfunction contribute to a wide range of human diseases. Considering the limitation of conventional antioxidants and that mitochondria are the main source of reactive oxygen species (ROS) which induce oxidative damage, mitochondria-targeted antioxidants which can selectively block mitochondrial oxidative damage and prevent various types of cell death have been widely developed. As a lipophilic cation, triphenylphosphonium (TPP) has been commonly used in designing mitochondria-targeted antioxidants. Conjugated with the TPP moiety, antioxidants can achieve more than 1000-fold higher mitochondrial concentration depending on cell membrane potentials and mitochondrial membrane potentials. Herein we discuss the deficiencies of conventional antioxidants and the advantages of mitochondrial targeting, and review various types of TPP-based mitochondria-targeted antioxidants. These provide theoretical and background support for the design of new anti-oxidant. 相似文献
55.
Potential mGAT4 inhibitors derived from the lead substance (S)-SNAP-5114 have been synthesized and characterized for their inhibitory potency. Variations from the parent compound included the substitution of one of its aromatic 4-methoxy and 4-methoxyphenyl groups, respectively, with a more polar moiety, including a carboxylic acid, alcohol, nitrile, carboxamide, sulfonamide, aldehyde or ketone function, or amino acid partial structures. Furthermore, it was investigated how the substitution of more than one of the aromatic 4-methoxy groups affects the potency and selectivity of the resulting compounds. Among the synthesized test substances (S)-1-{2-[(4-formylphenyl)bis(4-methoxyphenyl)-methoxy]ethyl}piperidine-3-carboxylic acid, that features a carbaldehyde function in place of one of the aromatic 4-methoxy moieties of (S)-SNAP-5114, was found to have a pIC50 value of 5.89±0.07, hence constituting a slightly more potent mGAT4 inhibitor than the parent substance while showing comparable subtype selectivity. 相似文献
56.
57.
58.
59.
V. I. Zubkov O. V. Kucherova I. N. Yakovlev A. V. Solomonov 《Russian Microelectronics》2015,44(3):203-209
An automated system for integrated electrophysical and optical studies of semiconductor nanoheterostructures, which operates in a wide temperature range from 15 to 475 K, is designed. The setup is intended to measure the temperature and frequency admittance and electroluminescence spectra of light-emitting diode and laser chips formed on substrates of diameter up to 50.2 mm, and the distribution of parameters over the wafer. The setup includes the closed-cycle helium cryogenic station, LCR meter, and temperature controller. The characterization results of nanoheterostructures with InGaN/GaN multiple quantum wells, which are used for creating highly efficient white and blue light-emitting diodes, are presented. 相似文献
60.
I. N. Andronov Yu. I. Ryabkov N. P. Bogdanov N. A. Severova A. N. Danilov I. V. Churilina 《Russian Metallurgy (Metally)》2015,2015(10):778-784
The influence of the thermal cycling conditions on the thermal-cycling creep of a TN-1 alloy and the related irreversible deformations is studied. The conditions under which an anomalous increase in the irreversible deformations begins are determined. The structural mechanism of the irreversible deformations of an equiatomic alloy is shown to be analogous to the structural mechanism of metal creep at high temperatures: it predominantly has a dislocation character. It is proposed to use the effect of anomalous increase in the deformation of materials with reversible martensitic transformations for forming parts made of these materials at low temperatures. 相似文献