全文获取类型
收费全文 | 406545篇 |
免费 | 6524篇 |
国内免费 | 3659篇 |
专业分类
化学 | 174916篇 |
晶体学 | 5304篇 |
力学 | 17462篇 |
综合类 | 189篇 |
数学 | 52282篇 |
物理学 | 112770篇 |
无线电 | 53805篇 |
出版年
2021年 | 2490篇 |
2020年 | 2771篇 |
2019年 | 3020篇 |
2018年 | 12573篇 |
2017年 | 13453篇 |
2016年 | 9356篇 |
2015年 | 4643篇 |
2014年 | 5578篇 |
2013年 | 13549篇 |
2012年 | 14789篇 |
2011年 | 25344篇 |
2010年 | 16305篇 |
2009年 | 16384篇 |
2008年 | 22552篇 |
2007年 | 26310篇 |
2006年 | 11359篇 |
2005年 | 17884篇 |
2004年 | 13170篇 |
2003年 | 12166篇 |
2002年 | 10055篇 |
2001年 | 9496篇 |
2000年 | 7788篇 |
1999年 | 6095篇 |
1998年 | 5330篇 |
1997年 | 5296篇 |
1996年 | 5056篇 |
1995年 | 4745篇 |
1994年 | 4553篇 |
1993年 | 4556篇 |
1992年 | 4722篇 |
1991年 | 4769篇 |
1990年 | 4495篇 |
1989年 | 4294篇 |
1988年 | 4262篇 |
1987年 | 3673篇 |
1986年 | 3515篇 |
1985年 | 4604篇 |
1984年 | 4761篇 |
1983年 | 3979篇 |
1982年 | 4272篇 |
1981年 | 4108篇 |
1980年 | 3952篇 |
1979年 | 3974篇 |
1978年 | 4193篇 |
1977年 | 3917篇 |
1976年 | 4148篇 |
1975年 | 3706篇 |
1974年 | 3804篇 |
1973年 | 4185篇 |
1972年 | 2580篇 |
排序方式: 共有10000条查询结果,搜索用时 796 毫秒
61.
Star copolymers have attracted significant interest due to their different characteristics compared with diblock copolymers, including higher critical micelle concentration, lower viscosity, unique spatial shape, or morphologies. Development of synthetic skills such as anionic polymerization and controlled radical polymerization have made it possible to make diverse architectures of polymers. Depending on the molecular architecture of the copolymer, numerous morphologies are possible, for instance, Archimedean tiling patterns and cylindrical microdomains at symmetric volume fraction for miktoarm star copolymers as well as asymmetric lamellar microdomains for star‐shaped copolymers, which have not been reported for linear block copolymers. In this review, we focus on morphologies and microphase separations of miktoarm (AmBn and ABC miktoarm) star copolymers and star‐shaped [(A‐b‐B)n] copolymers with nonlinear architecture. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1–21 相似文献
62.
Semiconductors - We found bulk n-GaAs layers grown by liquid phase epitaxy to be irregularly stressed. Deformation created by this stress causes a small but detectable quadrupole splitting of... 相似文献
63.
Bakhale Mugdha Hemalatha V. Dhanalakshmi Samiappan Kumar R. Siddharth Jain M. 《Wireless Personal Communications》2020,110(2):573-592
Wireless Personal Communications - A relatively new area of research and development is Swarm Robotics. It is a part of the swarm intelligence field. In the proposed paper, we shall use swarm... 相似文献
64.
M. Kroon E. Andreasson E. Persson Jutemar V. Petersson L. Persson M. Dorn P.A.T. Olsson 《Experimental Mechanics》2018,58(1):75-86
Injection-moulding is one of the most common manufacturing processes used for polymers. In many applications, the mechanical properties of the product is of great importance. Injection-moulding of thin-walled polymer products tends to leave the polymer structure in a state where the mechanical properties are anisotropic, due to alignment of polymer chains along the melt flow direction. The anisotropic elastic-viscoplastic properties of low-density polyethylene, that has undergone an injection-moulding process, are therefore examined in the present work. Test specimens were punched out from injection-moulded plates and tested in uniaxial tension. Three in-plane material directions were investigated. Because of the small thickness of the plates, only the in-plane properties could be determined. Tensile tests with both monotonic and cyclic loading were performed, and the local strains on the surface of the test specimens were measured using image analysis. True stress vs. true strain diagrams were constructed, and the material response was evaluated using an elastic-viscoplasticity law. The components of the anisotropic compliance matrix were determined together with the direction-specific plastic hardening parameters. 相似文献
65.
Anjan Biswas Sonmezoglu Abdullah Ekici Mehmet Alzahrani Abdullah Khamis Belic Milivoj R. 《Journal of Communications Technology and Electronics》2020,65(12):1384-1398
Journal of Communications Technology and Electronics - This paper implements mathematically rigorous extended trial function algorithm to address cubic–quartic optical solitons in... 相似文献
66.
67.
68.
69.
70.