全文获取类型
收费全文 | 3565篇 |
免费 | 441篇 |
国内免费 | 282篇 |
专业分类
化学 | 464篇 |
晶体学 | 3篇 |
力学 | 163篇 |
综合类 | 15篇 |
数学 | 1102篇 |
物理学 | 949篇 |
无线电 | 1592篇 |
出版年
2024年 | 10篇 |
2023年 | 37篇 |
2022年 | 33篇 |
2021年 | 65篇 |
2020年 | 98篇 |
2019年 | 65篇 |
2018年 | 78篇 |
2017年 | 126篇 |
2016年 | 146篇 |
2015年 | 136篇 |
2014年 | 239篇 |
2013年 | 227篇 |
2012年 | 238篇 |
2011年 | 324篇 |
2010年 | 221篇 |
2009年 | 254篇 |
2008年 | 252篇 |
2007年 | 241篇 |
2006年 | 234篇 |
2005年 | 203篇 |
2004年 | 162篇 |
2003年 | 156篇 |
2002年 | 127篇 |
2001年 | 80篇 |
2000年 | 89篇 |
1999年 | 60篇 |
1998年 | 70篇 |
1997年 | 51篇 |
1996年 | 49篇 |
1995年 | 29篇 |
1994年 | 19篇 |
1993年 | 31篇 |
1992年 | 24篇 |
1991年 | 14篇 |
1990年 | 12篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 14篇 |
1986年 | 9篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1978年 | 6篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1973年 | 3篇 |
1936年 | 1篇 |
排序方式: 共有4288条查询结果,搜索用时 0 毫秒
151.
《Acta Crystallographica. Section C, Structural Chemistry》2018,74(1):31-36
In order to determine the impact of different substituents and their positions on intermolecular interactions and ultimately on the crystal packing, unsubstituted N‐phenyl‐2‐phthalimidoethanesulfonamide, C16H14N2O4S, (I), and the N‐(4‐nitrophenyl)‐, C16H13N3O6S, (II), N‐(4‐methoxyphenyl)‐, C16H16N3O6S, (III), and N‐(2‐ethylphenyl)‐, as the monohydrate, C18H18N2O4S·H2O, (IV), derivatives have been characterized by single‐crystal X‐ray crystallography. Sulfonamides (I) and (II) have triclinic crystal systems, while (III) and (IV) are monoclinic. Although the molecules differ from each other only with respect to small substituents and their positions, they crystallized in different space groups as a result of differing intra‐ and intermolecular hydrogen‐bond interactions. The structures of (I), (II) and (III) are stabilized by intermolecular N—H…O and C—H…O hydrogen bonds, while that of (IV) is stabilized by intermolecular O—H…O and C—H…O hydrogen bonds. All four structures are of interest with respect to their biological activities and have been studied as part of a program to develop anticonvulsant drugs for the treatment of epilepsy. 相似文献
152.
Kazuhiro Nakabayashi Shigeki Sobu Yuji Kosuge Hideharu Mori 《Journal of polymer science. Part A, Polymer chemistry》2018,56(19):2175-2182
This work demonstrates the UV nanoimprinting lithography (UV-NIL) of high refractive index and highly transparent polythioethers based on thiol-ene click chemistry. Herein, 9,9-bis(3-mercaptopropylphenylether)fluorene (BMPF) is designed as a new thiol monomer with a high refractive index, high transparency, and good processability for UV-NIL. Colorless polythioethers are synthesized from BMPF and ene monomers under mild thiol-ene click reaction conditions. Excellent transmittance (96%) of 400 nm light is observed in all the polymer films and high refractive index values of 1.5972–1.6382 are attained. UV-NIL using thiol-ene photopolymerization affords polymer nanoimprinting patterns with various features on the order of 100–500 nm without any fractures. To the best of our knowledge, this is the first report on UV-NIL of high refractive index and highly transparent polymers. Through proper monomer and polymer design, novel polythioethers with suitable glass transition temperature (T g) values are developed with high refractive index, high transparency, and good UV-NIL processability. Furthermore, UV-NIL based on thiol-ene click chemistry is accomplished at the nanoscale. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2175–2182 相似文献
153.
154.
155.
156.
157.
Zi Jun Wang Milan Maric 《Journal of polymer science. Part A, Polymer chemistry》2013,51(13):2970-2978
Candidate materials for low‐loss optical waveguides based on poly(glycidyl methacrylate‐ran‐pentafluostyrene) [P(GMA‐ran‐PFS)] copolymers were synthesized by nitroxide mediated polymerization (NMP) initiated with BlocBuilder® [N‐(2‐methylpropyl)‐N‐(1‐diethlphosphono‐2,2‐dimethylpropyl)‐O‐(2‐carboxylprop‐2‐yl) hydroxylamine] bearing a succinimidyl ester group (NHS‐BlocBuilder) at 90 °C in 1,4 dioxane. The copolymerizations yielded copolymers with low dispersity Mw/Mn between 1.2 and 1.4. The core structure of single‐mode channel waveguides was fabricated by direct UV lithographic patterning. The copolymers with low Mw/Mn resulted in line width roughness (LWR) of about 0.16 μm, whereas LWR of copolymers with Mw/Mn=3.5 but similar compositions was about 0.5 μm. The improvement in microstructural control allotted by NMP permitted finer pattern replication for copolymers desired for optical waveguides, as suggested for photoresist polymers. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2970–2978 相似文献
158.
Takeo Sasaki Takumi Yoneyama Shota Hashimoto Sumie Takemura Yumiko Naka 《Journal of polymer science. Part A, Polymer chemistry》2013,51(18):3873-3880
Photoinduced depolymerization of poly(olefin sulfone)s possessing photobase generators in the side‐chain was investigated. Irradiation with UV light generated base on the side‐chains and induced depolymerization based on proton abstraction on the main‐chain. The effect of the length of the spacer chain, which connects the photobase‐generating moiety to the polymer main chain on the photoinduced depolymerization, also was investigated. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3873–3880 相似文献
159.
Mahyar Nasabi Khashayar Khoshmanesh Francisco J. Tovar‐Lopez Kourosh Kalantar‐zadeh Arnan Mitchell 《Electrophoresis》2013,34(22-23):3150-3154
This paper demonstrates the utilization of 3D semispherical shaped microelectrodes for dielectrophoretic manipulation of yeast cells. The semispherical microelectrodes are capable of producing strong electric field gradients, and in turn dielectrophoretic forces across a large area of channel cross‐section. The semispherical shape of microelectrodes avoids the formation of undesired sharp electric fields along the structure and also minimizes the disturbance of the streamlines of nearby passing fluid. The advantage of semispherical microelectrodes over the planar microelectrodes is demonstrated in a series of numerical simulations and proof‐of‐concept experiments aimed toward immobilization of viable yeast cells. 相似文献
160.