全文获取类型
收费全文 | 6529篇 |
免费 | 840篇 |
国内免费 | 804篇 |
专业分类
化学 | 5182篇 |
晶体学 | 103篇 |
力学 | 268篇 |
综合类 | 52篇 |
数学 | 825篇 |
物理学 | 1743篇 |
出版年
2024年 | 12篇 |
2023年 | 82篇 |
2022年 | 152篇 |
2021年 | 183篇 |
2020年 | 204篇 |
2019年 | 243篇 |
2018年 | 197篇 |
2017年 | 159篇 |
2016年 | 271篇 |
2015年 | 313篇 |
2014年 | 348篇 |
2013年 | 460篇 |
2012年 | 548篇 |
2011年 | 531篇 |
2010年 | 403篇 |
2009年 | 383篇 |
2008年 | 445篇 |
2007年 | 399篇 |
2006年 | 336篇 |
2005年 | 310篇 |
2004年 | 264篇 |
2003年 | 248篇 |
2002年 | 337篇 |
2001年 | 248篇 |
2000年 | 164篇 |
1999年 | 130篇 |
1998年 | 91篇 |
1997年 | 63篇 |
1996年 | 72篇 |
1995年 | 53篇 |
1994年 | 58篇 |
1993年 | 40篇 |
1992年 | 35篇 |
1991年 | 39篇 |
1990年 | 29篇 |
1989年 | 18篇 |
1988年 | 14篇 |
1987年 | 18篇 |
1986年 | 15篇 |
1985年 | 22篇 |
1984年 | 11篇 |
1983年 | 8篇 |
1982年 | 10篇 |
1980年 | 28篇 |
1978年 | 23篇 |
1977年 | 49篇 |
1976年 | 18篇 |
1975年 | 18篇 |
1974年 | 11篇 |
1943年 | 10篇 |
排序方式: 共有8173条查询结果,搜索用时 0 毫秒
1.
2.
Sung Hwan Koo Dong Jun Li Taeyeong Yun Dong Sung Choi Kyung Eun Lee Gil Yong Lee Youngtak Oh Joonwon Lim Suchithra Padmajan Sasikala Ho Jin Lee In Ho Kim Hong Ju Jung Rishabh Jain Sang Ouk Kim 《Particle & Particle Systems Characterization》2019,36(7)
Efficient water electrolysis catalyst is highly demanded for the production of hydrogen as a sustainable energy fuel. It is reported that cobalt derived nanoparticle (CoS2, CoP, CoS|P) decorated reduced graphene oxide (rGO) composite aerogel catalysts for highly active and reliable hydrogen evolution reaction electrocatalysts. 7 nm level cobalt derived nanoparticles are synthesized over graphene aerogel surfaces with excellent surface coverage and maximal expose of active sites. CoS|P/rGO hybrid aerogel composites show an excellent catalytic activity with overpotential of ≈169 mV at a current density of ≈10 mA cm?2. Accordingly, efficient charge transfer is attained with Tafel slope of ≈52 mV dec?1 and a charge transfer resistance (Rct) of ≈12 Ω. This work suggests a viable route toward ultrasmall, uniform nanoparticles decorated graphene surfaces with well‐controlled chemical compositions, which can be generally useful for various applications commonly requiring large exposure of active surface area as well as robust interparticle charger transfer. 相似文献
3.
We initiate a program to study certain recent problems in non-compact coset CFT by the BRST approach. We derive a reduction formula for the BRST cohomology by making use of a twisting by highest weight modules. As illustrations, we apply the formula to the bosonic string model and a rank one non-compact coset model [DPL]. Our formula provides a completely new approach to non-compact coset construction.Partially supported by NSF Grant DMS-8703581 相似文献
4.
5.
6.
7.
Sang Kyu Lee Min Ju Cho Jung‐Il Jin Dong Hoon Choi 《Journal of polymer science. Part A, Polymer chemistry》2007,45(3):531-542
New photocrosslinkable maleimide copolymers have been synthesized by the attachment of a tricyanopyrrolidene‐based chromophore. The 2‐(3‐cyano‐4‐(2‐{4‐[hexyl‐(6‐hydroxy‐hexyl)‐amino]‐phenyl}‐vinyl)‐5‐oxo‐1‐{4‐[4‐(3‐oxo‐3‐phenyl‐propenyl)‐ phenoxy]‐butyl}‐1,5‐dihydro‐pyrrol‐2‐ylidene)‐malononitrile chromophore exhibits nonlinear optical activity and contains a chalcone moiety that is sensitive to UV light (λ = 330–360 nm) for crosslink formation. The maleimide monomers have also been functionalized with chalcone moieties. The resultant copolymers exhibit great processability, and one of them shows a maximum electrooptic coefficient of 90 pm/V at 1300 nm. We could control the thermal stability of the electrooptic coefficient with the newly synthesized photoreactive copolymers successfully. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 531–542, 2007 相似文献
8.
Ju Yeon Woo Eun Hee Kim Tae Hoon Yoon Jae Chang Kim Byung Kyu Kim 《Liquid crystals》2007,34(9):1115-1120
Chiral dopants were added to the formulation of holographic polymer-dispersed liquid crystals and the effects studied in terms of grating formation dynamics, morphology, diffraction efficiency, contrast ratio and electro-optical properties of the films. A gradual increase of real-time diffraction efficiency, decrease of droplet size and increase of diffraction efficiency of the composite film were obtained with the addition and increasing content of chiral dopant, due to the increased viscosity of the liquid crystal (LC) doped with the chiral dopant leading to decreased droplet coalescence. The contrast ratio decreased with increasing content of chiral dopant due to the difficult orientation of LC molecules caused by the formation of a helical structure. Addition of a small amount of the chiral dopant increased the driving voltage slightly, whereas the decay time is decreased significantly as a result of the high twisting of the helical structure. 相似文献
9.
Dirichlet boundary value problems for perturbed second-order differential equations on a half line are investigated in this paper. The methods mainly depend on the calculus of variations to the classical functionals. Sufficient conditions are obtained for the existence of the solutions. 相似文献
10.