全文获取类型
收费全文 | 845篇 |
免费 | 37篇 |
国内免费 | 73篇 |
专业分类
化学 | 341篇 |
晶体学 | 1篇 |
力学 | 35篇 |
数学 | 163篇 |
物理学 | 415篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 18篇 |
2021年 | 11篇 |
2020年 | 21篇 |
2019年 | 36篇 |
2018年 | 25篇 |
2017年 | 23篇 |
2016年 | 29篇 |
2015年 | 27篇 |
2014年 | 63篇 |
2013年 | 55篇 |
2012年 | 37篇 |
2011年 | 69篇 |
2010年 | 45篇 |
2009年 | 51篇 |
2008年 | 57篇 |
2007年 | 64篇 |
2006年 | 51篇 |
2005年 | 39篇 |
2004年 | 39篇 |
2003年 | 34篇 |
2002年 | 22篇 |
2001年 | 14篇 |
2000年 | 19篇 |
1999年 | 7篇 |
1998年 | 12篇 |
1997年 | 14篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 9篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1973年 | 3篇 |
排序方式: 共有955条查询结果,搜索用时 15 毫秒
951.
High-density polyethylene/carbon black foaming conductive composites were prepared from acetylene black(ACEY) and super conductive carbon black(HG-1P) as conductive filler, low-density polyethylene(LDPE) as the second component, ethylene-vinyl acetate(EVA) and ethylene propylene rubber(EPR) as the third component, azobisformamide(AC) as foamer, and dicumyl peroxide(DCP) as cross-linker. The structure and resistivity-temperature behavior of high-density polyethylene(HDPE)/CB foaming conductive composites were investigated. Influences of carbon black, LDPE, EVA, EPR, AC, and DCP on the foaming performance and resistivity-temperature behavior of HDPE/CB foaming conductive composites were also studied. The results reveal that HDPE/CB foaming conductive composite exhibits better switching characteristic; ACET-filled HDPE foaming conductive composite displays better positive temperature coefficient(PYC) effect; whereas super conductive carbon black(HG-1P)-filled HDPE foaming conductive composite shows better negative temperature coefficient(NTC) effect. 相似文献
952.
953.
954.
A novel hollow carbon derived from biomass lotus-root has been prepared by a one-step carbonization method. The carbon anode obtained at 900 ℃ showed the best electrochemical performance, corresponding to a high specific capacity of 445 mA∙h/g at 0.1 C, as well as excellent cycling stability after 500 cycles. Further investigation exhibits that the lithium storage of hollow carbon involves Li+ adsorption in the defect sites and Li+ insertion. The results showed that the intrinsic structure of lotus root can inspire us to prepare biomass carbon with a hollow structure as an excellent anode for lithium-ion batteries. 相似文献
955.
Hui-Ying Sun Dr. Yin-Shan Meng Dr. Liang Zhao Nian-Tao Yao Pan-Dong Mao Qiang Liu Fei-Fei Yan Prof. Hiroki Oshio Prof. Tao Liu 《Angewandte Chemie (International ed. in English)》2023,62(28):e202302815
Colossal and anisotropic thermal expansion is a key function for microscale or nanoscale actuators in material science. Herein, we present a hexanuclear compound of [(Tp*)FeIII(CN)3]4[FeII(Ppmp)]2⋅2 CH3OH ( 1 , Tp*=hydrotris(3,5-dimethyl-pyrazol-1-yl)borate and Ppmp=2-[3-(2′-pyridyl)pyrazol-1-ylmethyl]pyridine), which has a rhombic core structure abbreviated as {FeIII2FeII2}. Magnetic susceptibility measurements and single-crystal X-ray diffraction analyses revealed that 1 underwent thermally-induced spin transition with the thermal hysteresis. The FeII site in 1 behaved as a spin crossover (SCO) unit, and significant deformation of its octahedron was observed during the spin transition process. Moreover, the distortion of the FeII centers actuated anisotropic deformation of the rhombic {FeIII2FeII2} core, which was spread over the whole crystal through the subsequent molecular rearrangements, leading to the colossal anisotropic thermal expansion. Our results provide a rational strategy for realizing the colossal anisotropic thermal expansion and shape memory effects by tuning the magnetic bistability. 相似文献