全文获取类型
收费全文 | 898篇 |
免费 | 72篇 |
国内免费 | 8篇 |
专业分类
化学 | 664篇 |
晶体学 | 8篇 |
力学 | 28篇 |
数学 | 97篇 |
物理学 | 181篇 |
出版年
2023年 | 2篇 |
2022年 | 16篇 |
2021年 | 34篇 |
2020年 | 17篇 |
2019年 | 23篇 |
2018年 | 18篇 |
2017年 | 14篇 |
2016年 | 35篇 |
2015年 | 28篇 |
2014年 | 39篇 |
2013年 | 56篇 |
2012年 | 68篇 |
2011年 | 80篇 |
2010年 | 64篇 |
2009年 | 50篇 |
2008年 | 63篇 |
2007年 | 49篇 |
2006年 | 31篇 |
2005年 | 39篇 |
2004年 | 34篇 |
2003年 | 31篇 |
2002年 | 37篇 |
2001年 | 20篇 |
2000年 | 14篇 |
1999年 | 9篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1934年 | 1篇 |
排序方式: 共有978条查询结果,搜索用时 15 毫秒
841.
842.
Yeon‐Wook Chung Byung‐Ill Lee Hyun‐Yu Kim Ulrich Wiesner Byoung‐Ki Cho 《Journal of polymer science. Part A, Polymer chemistry》2007,45(21):4988-4994
We prepared third‐generation amphiphilic dendrons 3‐14 and 3‐18 consisting of a hydrophilic aliphatic polyether dendritic core and either tetradecyl or octadecyl peripheries, respectively. Their solid‐state self‐assembly behavior was investigated by comparison with 3‐22 having the same dendritic core and longer docosyl peripheries. In marked contrast to the lamellar assembly of 3‐22 , small‐angle X‐ray analysis suggested that 3‐14 and 3‐18 show oblique columnar structures with presumably elliptical cross sections. The observed results can be rationalized by dendron shape anisotropy, which is strongly associated with the degree of crystallization as a function of alkyl chain length. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4988–4994, 2007 相似文献
843.
Jin Uk Ju Dae Sung Chung Seul Ong Kim Sung Ouk Jung Chan Eon Park Yun‐Hi Kim Soon‐Ki Kwon 《Journal of polymer science. Part A, Polymer chemistry》2009,47(6):1609-1616
A new p‐type conjugated copolymer, poly(9,10‐diethynylanthracene‐alt‐9,9‐didodecylfluorene) (PDADF), which is composed of ethynyl‐linked alternating anthracene/fluorene, is synthesized via a palladium(II)‐catalyzed Sonogashira coupling reaction with 9,10‐diethynylanthracene and 2,7‐diiodo‐9,9‐didodecyl‐fluorene. The obtained polymer is confirmed by FTIR, 1H‐NMR, 13C‐NMR and elemental analysis. The PDADF had very good solubility in organic solvents such as chloroform and had a weight average molecular weight of 29,300 with a polydispersity index of 1.29. The PL maximum of the polymer was found at 533 and 568 nm for a solution and 608 nm for film, respectively. The highest occupied molecular orbital (HOMO) energy of the polymer is ?5.62 eV as measured via cyclic voltammetry (CV). A solution‐processed thin film transistor device showed a carrier mobility value of 6.0 × 10?4 cm2/Vs with a threshold voltage of ?17 V and a capacitance (Ci) of 10 nF/cm2. The out‐of‐plane and in‐plane GIXD pattern of spin‐coated polymer on SiO2 dielectric surfaces showed an amorphous halo near 2θ = 20°. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1609–1616, 2009 相似文献
844.
845.
Man Jung Han Keun Bae Choi Ki Ho Kim Bo Sup Hahn Won Young Lee 《Macromolecular Symposia》1990,33(1):301-309
To synthesize targeting polymeric antitumor agents, poly[(2-acetoxy-3,4-dihydro-2H-pyran)-alt-(maleic anhydride)] as polymer backbone, chlorophyll derivatives(CpD) extracted from silkworm excreta as targeting moiety and 5-fluorouracil and 6-mercaptopurine as pharmacons were selected. The polymer exhibited an antitumor activity comparable to that of cyclophosphamide in vivo. CpD as well as CpD-polymer conjugate were localized on tumor cells in vitro and delivered to tumor tissues in vivo specifically. The targeting polymeric antitumor agents were synthesized by coupling pharmacons and CpD on the polymer chain with the aid of reactions between functionalities of the reactants and anhydride groups on the polymer backbone. Various tests of their biological activities in vivo are in progress. 相似文献
846.
Ho Bum Park Jae Hoon Kim Jang Ki Kim Young Moo Lee 《Macromolecular rapid communications》2002,23(9):544-550
The role of polydimethylsiloxane (PDMS) as a compatibilizer of polyimide/silica hybrid composites was investigated. Introduction of PDMS into a polyimide matrix retards the phase separation of hybrid composites and also prevents the formation of high‐molecular‐weight silicate. PDMS interacts with silica because of the similarity of its structure with the sol‐gel glass matrix of the silica precursor, indicating that poly(imide siloxane)/silica might be a good candidate material for organic/inorganic hybrid composites. 相似文献
847.
848.
849.
850.