全文获取类型
收费全文 | 11907篇 |
免费 | 1701篇 |
国内免费 | 1414篇 |
专业分类
化学 | 8128篇 |
晶体学 | 147篇 |
力学 | 855篇 |
综合类 | 95篇 |
数学 | 1423篇 |
物理学 | 4374篇 |
出版年
2024年 | 19篇 |
2023年 | 169篇 |
2022年 | 206篇 |
2021年 | 291篇 |
2020年 | 389篇 |
2019年 | 345篇 |
2018年 | 308篇 |
2017年 | 295篇 |
2016年 | 452篇 |
2015年 | 430篇 |
2014年 | 562篇 |
2013年 | 806篇 |
2012年 | 886篇 |
2011年 | 967篇 |
2010年 | 652篇 |
2009年 | 712篇 |
2008年 | 752篇 |
2007年 | 722篇 |
2006年 | 684篇 |
2005年 | 627篇 |
2004年 | 493篇 |
2003年 | 393篇 |
2002年 | 353篇 |
2001年 | 331篇 |
2000年 | 293篇 |
1999年 | 319篇 |
1998年 | 328篇 |
1997年 | 268篇 |
1996年 | 265篇 |
1995年 | 224篇 |
1994年 | 244篇 |
1993年 | 161篇 |
1992年 | 150篇 |
1991年 | 131篇 |
1990年 | 139篇 |
1989年 | 84篇 |
1988年 | 80篇 |
1987年 | 87篇 |
1986年 | 82篇 |
1985年 | 71篇 |
1984年 | 48篇 |
1983年 | 33篇 |
1982年 | 35篇 |
1981年 | 26篇 |
1980年 | 20篇 |
1979年 | 15篇 |
1978年 | 14篇 |
1977年 | 8篇 |
1976年 | 8篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Ping Wang Hao Jin Wanli Liu Chunpeng Chai Zhihao Shen Haiqing Guo Xiaofang Chen Xinghe Fan Dechun Zou Qifeng Zhou 《Journal of polymer science. Part A, Polymer chemistry》2008,46(23):7861-7867
Nonconjugated bipolar transport polymers have been developed as host materials for electroluminescent devices by incorporating both electron‐transporting and hole‐transporting functionalities into copolymers. The random copolymer PCt‐nvk3‐7 containing mesogen‐jacketed segment of P‐Ct have been synthesized and characterized. The effect of mesogen‐jacketed segment content of these bipolar copolymers on device performance has been investigated. The results of polymer light‐emitting diodes (PLEDs) show that the jacketed content of copolymers has a significant effect on device performance: lowering charge transport and facilitating the hole‐electron recombination leads to much higher current efficiency. Applying these high triplet random copolymers as host, the maximum current efficiency of 0.70 cd/A and the maximum brightness of 1872.8 cd/m2 was achieved for PCt‐nvk3‐7 with an orange‐emitting complex dopant. The results suggest that the bipolar copolymers PCt‐nvks can be good host polymers for electrophosphorescent devices. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7861–7867, 2008 相似文献
992.
The thermodynamics of the association between 4,4′,4″-tris(dimethyl-amino)triphenylmethyl chloride (crystal violet or CV) and sodium bis(2-ethylhexyl)-sulfosuccinate (aerosol OT or AOT) in water/AOT/n-decane microemulsion and the kinetics of the basic hydrolysis of CV in a water-in-oil microemulsion were investigated by UV–vis spectroscopic measurements. An association model of CV and AOT was used to analyze the experimental data to obtain the association constants at various temperatures. By taking the association into account, the “actual” rate constants and the activation energies of the basic hydrolysis of CV in the media of water/AOT/oil were obtained. The difference in thermodynamics and kinetics between the two media of water/AOT/n-decane and water/AOT/isooctane is discussed. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 294–300, 2008 相似文献
993.
Hong C. Shen Author Vitae 《Tetrahedron》2009,65(20):3931-1252
994.
Xiaohua Shen 《Journal of Differential Equations》2008,244(11):2836-2869
A novel variational problem is investigated which comes from the study of the Ginzburg-Landau model of superconductivity with impurity inclusion. The feature of this variational problem is that it depends on the impurity set. Some properties of the variational problem are established and an application is given to the Ginzburg-Landau model of superconductivity with impurity inclusion. 相似文献
995.
JuPing Yang QiDi Zhao Bin Zhou HuaGang Ni XinPing Wang ZhiQuan Shen 《中国科学B辑(英文版)》2009,52(12):2295-2306
Most research on copolymers with fluorinated monomers has focused on the relationship between fluorinated monomer content
and the corresponding surface structure. However, the influence of the non-fluorinated block on the surface structure of the
copolymer film is unknown. Various molecular weight poly(butyl methacrylates) (PBMA) end-capped with 2-perfluorooctylethyl
methacrylate (FMA) units (PBMA-ec-FMA) have been synthesized by atom transfer radical polymerization (ATRP). The effect of the PBMA block length on the surface
structure and properties of the polymers both in the solid state and in solution was investigated using various techniques.
X-ray photoelectron spectroscopy (XPS), sum frequency generation (SFG) vibrational spectroscopy and X-ray diffraction (XRD)
analyses indicated that longer PBMA blocks enhanced both the enrichment of the fluorinated moieties and the order of the packing
orientation of the perfluoroalkyl side chains on the surface. This enhancement was attributed mainly to the molecular aggregate
structure of the end-capped polymers with long PBMA blocks in the solution and to the interfacial structure at the air/liquid
interface, which favors the -(CF2)7CF3 moieties self-assembling on the polymer surface during film formation. This observation suggests that the polyacrylate block
structure in fluorinated diblock copolymers, in addition to the fluorinated monomer content, plays an important role in structure
formation on the solid surface. 相似文献
996.
997.
Hongchao Liu Hua Wang Jianghan Shen Ying Sun Zhongmin Liu 《Reaction Kinetics and Catalysis Letters》2008,93(1):11-17
The high-throughput technique has been successfully employed to investigate systematically NH3 decomposition catalysts for COx-free hydrogen production. Supported γ-Mo2N catalysts not only could be prepared and evaluated by the high-throughput experiment, but are also active for NH3 decomposition luke supported Ni and Co catalysts. Additionally, the preparation process and support play important roles
on the catalytic performance of supported γ-Mo2N catalysts. 相似文献
998.
999.
1000.
首先讨论了表观传递函数的近似计算,然后用e指数近似公式进行了象差平衡并求得容限,为利用表观传递函数评价部分相干光学系统的成象质量提供了方法和依据。 相似文献