全文获取类型
收费全文 | 452700篇 |
免费 | 11941篇 |
国内免费 | 5747篇 |
专业分类
电工技术 | 12922篇 |
技术理论 | 11篇 |
综合类 | 6879篇 |
化学工业 | 62514篇 |
金属工艺 | 23500篇 |
机械仪表 | 20214篇 |
建筑科学 | 15430篇 |
矿业工程 | 4647篇 |
能源动力 | 10609篇 |
轻工业 | 26849篇 |
水利工程 | 4985篇 |
石油天然气 | 10876篇 |
武器工业 | 713篇 |
无线电 | 58667篇 |
一般工业技术 | 85708篇 |
冶金工业 | 72648篇 |
原子能技术 | 6749篇 |
自动化技术 | 46467篇 |
出版年
2023年 | 2109篇 |
2022年 | 3603篇 |
2021年 | 5706篇 |
2020年 | 4314篇 |
2019年 | 4334篇 |
2018年 | 14142篇 |
2017年 | 15044篇 |
2016年 | 10558篇 |
2015年 | 6569篇 |
2014年 | 8709篇 |
2013年 | 17907篇 |
2012年 | 15426篇 |
2011年 | 24242篇 |
2010年 | 21271篇 |
2009年 | 21343篇 |
2008年 | 21606篇 |
2007年 | 23301篇 |
2006年 | 14473篇 |
2005年 | 16670篇 |
2004年 | 13162篇 |
2003年 | 12044篇 |
2002年 | 10306篇 |
2001年 | 10212篇 |
2000年 | 9843篇 |
1999年 | 10931篇 |
1998年 | 24257篇 |
1997年 | 16756篇 |
1996年 | 13360篇 |
1995年 | 9805篇 |
1994年 | 8467篇 |
1993年 | 8074篇 |
1992年 | 5511篇 |
1991年 | 5162篇 |
1990年 | 4882篇 |
1989年 | 4484篇 |
1988年 | 4025篇 |
1987年 | 3162篇 |
1986年 | 3164篇 |
1985年 | 3466篇 |
1984年 | 3020篇 |
1983年 | 2677篇 |
1982年 | 2520篇 |
1981年 | 2609篇 |
1980年 | 2267篇 |
1979年 | 2061篇 |
1978年 | 2003篇 |
1977年 | 2456篇 |
1976年 | 3465篇 |
1975年 | 1666篇 |
1974年 | 1593篇 |
排序方式: 共有10000条查询结果,搜索用时 750 毫秒
91.
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
92.
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
93.
94.
95.
96.
Wan‐Xia Wu 《Polymer International》2019,68(11):1848-1855
A series of novel aliphatic poly(β‐thioether ester)s with various methylene group contents were prepared by direct lipase‐catalyzed polycondensation of the monomer with an acid‐labile β‐thiopropionate group. The polycondensation reaction using immobilized lipase B from Candida antarctica was carried out in diphenyl ether at 90 °C. Poly(β‐thioether ester)s with high molecular weights of 20 500–57 000 Da and narrow polydispersities in the range 1.40–1.48 were obtained. Thermogravimetric analysis, differential scanning calorimetry and wide‐angle X‐ray diffraction were used to investigate the thermal properties and crystal structures of these polyesters. All the poly(β‐thioether ester)s were semicrystalline polymers and thermally stable up to at least 200 °C. In vitro degradation studies showed that they can rapidly degrade under acidic conditions by the hydrolysis of the β‐thiopropionate groups, suggesting their potential as acid‐degradable polymeric materials. © 2019 Society of Chemical Industry 相似文献
97.
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
98.
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
99.
100.