全文获取类型
收费全文 | 35016篇 |
免费 | 1091篇 |
国内免费 | 265篇 |
专业分类
化学 | 24665篇 |
晶体学 | 280篇 |
力学 | 684篇 |
综合类 | 1篇 |
数学 | 5960篇 |
物理学 | 4782篇 |
出版年
2023年 | 167篇 |
2022年 | 324篇 |
2021年 | 431篇 |
2020年 | 611篇 |
2019年 | 599篇 |
2018年 | 417篇 |
2017年 | 389篇 |
2016年 | 943篇 |
2015年 | 831篇 |
2014年 | 1005篇 |
2013年 | 1706篇 |
2012年 | 2180篇 |
2011年 | 2462篇 |
2010年 | 1329篇 |
2009年 | 1181篇 |
2008年 | 2274篇 |
2007年 | 2093篇 |
2006年 | 2117篇 |
2005年 | 1968篇 |
2004年 | 1687篇 |
2003年 | 1380篇 |
2002年 | 1335篇 |
2001年 | 486篇 |
2000年 | 469篇 |
1999年 | 408篇 |
1998年 | 397篇 |
1997年 | 418篇 |
1996年 | 449篇 |
1995年 | 314篇 |
1994年 | 368篇 |
1993年 | 335篇 |
1992年 | 303篇 |
1991年 | 278篇 |
1990年 | 244篇 |
1989年 | 210篇 |
1988年 | 210篇 |
1987年 | 221篇 |
1986年 | 180篇 |
1985年 | 376篇 |
1984年 | 331篇 |
1983年 | 280篇 |
1982年 | 342篇 |
1981年 | 277篇 |
1980年 | 288篇 |
1979年 | 240篇 |
1978年 | 227篇 |
1977年 | 217篇 |
1976年 | 208篇 |
1975年 | 186篇 |
1974年 | 160篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Synthesis of diisocyanides with phenolic groups and their polymerization to helically chiral poly(quinoxaline‐2,3‐diyl)s 下载免费PDF全文
Johannes Scholz Michael Reggelin 《Journal of polymer science. Part A, Polymer chemistry》2015,53(11):1320-1329
The development of synthetic routes which lead to five new diisocyanide monomers with one or two phenolic groups is described. Their polymerization behavior is studied with Pd‐ and Ni‐based initiators, as well as under microwave irradiation. The polymerizability is mainly dominated by steric effects as is concluded from experiments using different protecting groups. Chiroptical properties of these new polymers are studied by CD‐spectroscopy. After deprotection, helically chiral poly(quinoxalin‐2,3‐diyl)s are obtained which display a Brønsted function attached to a stereolabile biaryl axis whose configuration should be influenced by the chiral polymer backbone. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1320–1329 相似文献
3.
4.
5.
6.
Amphiphilic thermoset elastomers from metal‐free,click crosslinking of PEG‐grafted silicone surfactants 下载免费PDF全文
Michael A. Brook Frances Lasowski Heather Sheardown 《Journal of polymer science. Part A, Polymer chemistry》2015,53(9):1082-1093
The hydrophobicity of silicone elastomers can compromise their utility in some biomaterials applications. Few effective processes exist to introduce hydrophilic groups onto a polysiloxane backbone and subsequently crosslink the material into elastomers. This problem can be overcome through the utilization of metal‐free click reactions between azidoalkylsilicones and alkynyl‐modified silicones and/or PEGs to both functionalize and crosslink silicone elastomers. Alkynyl‐functional PEG was clicked onto a fraction of the available azido groups of a functional polysiloxane, yielding azido reactive PDMS‐g‐PEG rake surfactants. The reactive polymers were then used to crosslink alkynyl‐terminated PDMS of different molecular weights. Using simple starting materials, this generic yet versatile method permits the preparation and characterization of a library of amphiphilic thermoset elastomers that vary in their composition, crosslink density, elasticity, hydrogel formation, and wettability. An appropriate balance of PEG length and crosslink density leads to a permanently highly wettable silicone elastomer that demonstrated very low levels of protein adsorption. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1082–1093 相似文献
7.
Michael Dickson 《Foundations of Physics》2015,45(10):1330-1340
8.
9.
10.