全文获取类型
收费全文 | 1982篇 |
免费 | 67篇 |
国内免费 | 8篇 |
专业分类
化学 | 1605篇 |
晶体学 | 11篇 |
力学 | 18篇 |
数学 | 89篇 |
物理学 | 334篇 |
出版年
2023年 | 16篇 |
2022年 | 24篇 |
2021年 | 27篇 |
2020年 | 25篇 |
2019年 | 29篇 |
2018年 | 30篇 |
2017年 | 16篇 |
2016年 | 44篇 |
2015年 | 37篇 |
2014年 | 53篇 |
2013年 | 107篇 |
2012年 | 161篇 |
2011年 | 129篇 |
2010年 | 74篇 |
2009年 | 87篇 |
2008年 | 133篇 |
2007年 | 147篇 |
2006年 | 144篇 |
2005年 | 109篇 |
2004年 | 94篇 |
2003年 | 72篇 |
2002年 | 56篇 |
2001年 | 37篇 |
2000年 | 34篇 |
1999年 | 14篇 |
1998年 | 16篇 |
1997年 | 11篇 |
1996年 | 16篇 |
1995年 | 16篇 |
1994年 | 11篇 |
1993年 | 16篇 |
1992年 | 14篇 |
1991年 | 14篇 |
1990年 | 15篇 |
1989年 | 13篇 |
1988年 | 16篇 |
1987年 | 8篇 |
1986年 | 11篇 |
1985年 | 21篇 |
1984年 | 18篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1981年 | 12篇 |
1980年 | 8篇 |
1979年 | 15篇 |
1978年 | 12篇 |
1977年 | 10篇 |
1976年 | 10篇 |
1975年 | 7篇 |
1974年 | 10篇 |
排序方式: 共有2057条查询结果,搜索用时 31 毫秒
951.
Masaki Moritsugu Atsushi Sudo Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2011,49(24):5186-5191
Selective and quantitative cyclotrimerization of p‐tolylisocyanate proceeded by using sodium p‐toluenesulfinate as a catalyst and 1,3‐dimethylimidazolidinone as a solvent. Exploitation of this system to the cyclotrimerization of methylene diphenyl 4,4′‐diisocyanate (MDI) permitted formation of the corresponding networked polymer, which was selectively consisted of isocyanurate moiety and thus exhibited excellent thermal stability. Utilization of phenyl isocyanate (PhNCO) as a comonomer with varying feed ratio [MDI]0/[PhNCO]0 allowed successful control of flexibility of the networked polymers, while retaining its high thermal stability. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
952.
953.
Masaki Moritsugu Tomomi Shirota Shoichi Kubo Tomonari Ogata Osamu Sato Seiji Kurihara 《Journal of Polymer Science.Polymer Physics》2009,47(20):1981-1990
Photo‐chemically tunable photonic band gap materials are prepared by infiltration of liquid crystal polymers having azobenzene groups into voids of SiO2 inverse opal films. Linearly polarized (LP) light irradiation results in transformation from a random to an anisotropic molecular orientation of azobenzene side chains in the voids of the SiO2 inverse opal film, leading to the reversible and stable shift of the reflection peak to longer wavelength more than 15 nm. To improve switching properties, we use copolymers of azobenzene monomer and tolane monomer, which have higher birefringence, as infiltration materials into the voids. The azobenzene‐tolane copolymers are found to show higher birefringence than azobenzene homopolymers by the LP light irradiation at higher temperature. Consequently, the reflection band of the SiO2 inverse opal film infiltrated with the azobenzene‐tolane copolymer can be shifted to longer wavelength region more than 55 nm by the irradiation of LP light. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1981–1990, 2009 相似文献
954.
955.
956.
957.
958.
959.
Ryu Yamasaki Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2013,51(24):5215-5220
Isothiocyanate is a very useful functional group for post‐polymerization modification by the reaction with amine or alcohol. An isothiocyanate monomer, 4‐vinylbenzyl isothiocyanate, was synthesized from 4‐vinylbenzyl chloride without using any harmful reagents such as thiophosgene and CS2. The obtained monomer was successively polymerized by the conventional radical polymerization (AIBN, 1,4‐dioxane, 60 °C) to afford the corresponding polymer. The obtained polymer was characterized by 1H NMR, FTIR, thermogravimetric analysis (TGA), and differential scanning calorimetry. In contrast to the isocyanate group, the isothiocyanate group was relatively tolerant to alcohols, and this character enabled us to synthesize a copolymer of 4‐vinyl benzylisothiocyanate and (2‐hydroxyethyl methacrylate). The copolymer is transformed into networked polymer by 1,8‐diazabicyclo[5.4.0]undec‐7‐ene as a promoter of the reaction between isothiocyanate and alcohol to afford thiocarbamate. The formation of networked polymer was characterized by FTIR and TGA. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5215–5220 相似文献
960.
We have successfully demonstrated a novel sensing technique for monitoring the variation of solution concentrations and measuring the effective dielectric constant in a medium by means of an ultra-small and label-free nanosensor, the mechanism of which is based on the localized surface plasmon resonance (LSPR) of gold nanorods. The nanorods are fabricated in a narrow size distribution, which is characterized by transmission electron microscopy and optical absorption spectroscopy. In addition, we employ a simple analytical calculation to examine the LSPR band of the absorption spectrum, which provides excellent consistency with aspect ratio. The plasmonic sensing is performed by detecting the diffusion process and saturation concentration of hexadecyltrimethylammonium bromide in water, and tracing the effective dielectric constants of the medium simultaneously. This promising sensing and analytical technique can be easily used for investigating the nano-scale variations of mixing or reaction process in a micro/nanofluidic channel or the biological interaction in the cytoplasm of the cell. 相似文献