全文获取类型
收费全文 | 3897篇 |
免费 | 89篇 |
国内免费 | 32篇 |
专业分类
化学 | 3104篇 |
晶体学 | 63篇 |
力学 | 62篇 |
数学 | 184篇 |
物理学 | 605篇 |
出版年
2022年 | 22篇 |
2021年 | 30篇 |
2020年 | 33篇 |
2019年 | 37篇 |
2018年 | 24篇 |
2017年 | 34篇 |
2016年 | 46篇 |
2015年 | 72篇 |
2014年 | 82篇 |
2013年 | 273篇 |
2012年 | 173篇 |
2011年 | 231篇 |
2010年 | 134篇 |
2009年 | 109篇 |
2008年 | 202篇 |
2007年 | 206篇 |
2006年 | 222篇 |
2005年 | 208篇 |
2004年 | 195篇 |
2003年 | 206篇 |
2002年 | 201篇 |
2001年 | 52篇 |
2000年 | 59篇 |
1999年 | 60篇 |
1998年 | 49篇 |
1997年 | 42篇 |
1996年 | 56篇 |
1995年 | 54篇 |
1994年 | 46篇 |
1993年 | 30篇 |
1992年 | 34篇 |
1991年 | 31篇 |
1990年 | 32篇 |
1989年 | 36篇 |
1988年 | 41篇 |
1987年 | 30篇 |
1986年 | 26篇 |
1985年 | 53篇 |
1984年 | 52篇 |
1983年 | 29篇 |
1982年 | 57篇 |
1981年 | 43篇 |
1980年 | 58篇 |
1979年 | 59篇 |
1978年 | 45篇 |
1977年 | 31篇 |
1976年 | 24篇 |
1975年 | 28篇 |
1974年 | 29篇 |
1973年 | 19篇 |
排序方式: 共有4018条查询结果,搜索用时 15 毫秒
221.
222.
Recently, many studies have been started in search for materials which show a photoinduced phase transition (PIPT). In this work, we review two systems as typical examples of PIPT accompanied with changes in magnetic characteristics; (1) organo-metal complex [Fe(2-pic)3]Cl2 EtOH (2-pic = 2-amino-methyl-pyridine) and (2) III-V based magnetic semiconductors (In1-x , Mn x )As. In the former case, we show several nonlinear characteristics in dynamical process of photoinduced spin state transition from low-spin to high-spin states. In the latter one, photocarrier-induced ferromagnetic order has been observed by both magnetic and transport measurements. 相似文献
223.
(S)-(-)-Ipsenol (2b) and (S)-(+)-ipsdienol (4b), a major component of the sex pheromone of the bark beetle, and their enantiomers (3b and 5b) were prepared enantioselectively using tartrate esters of (2-bromoallyl)boronic acid in the key step. 相似文献
224.
Hisanao Yamamoto Akira Fujita Miyuki Harada Mitsukazu Ochi 《Molecular Crystals and Liquid Crystals》2014,588(1):41-50
A liquid crystalline epoxy resin (LCE) having α-methylstilbene as a mesogenic unit and an ethylene-oxy unit as a spacer (DGE(C2-MS-C2)) was synthesized and characterized. DGE (C2-MS-C2) has a lower melting point (MP) compared to the diglycidylether of 4,4′-dihydroxy-α-methylstilbene (DGEDHMS). The curing of DGE (C2-MS-C2) with diaminodiphenylethane (DDEt) in a mesophase generated a liquid crystalline (LC) network, which have a more highly layered structure than DGEDHMS. The LC network showed extensively large fracture energy on a tensile test. Introducing spacers outside the mesogen unit promotes the mesogen unit to form a highly ordered structure, which enhances the versatility of LC epoxy resins. 相似文献
225.
226.
227.
Takeshi Takeda Shuichi Kuroi Makoto Ozaki Akira Tsubouchi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5-6):1291-1296
Abstract Trialkylsilyl group-directed regioselective transformations of alkynyl thioacetals to alkynylcyclopropanes and enynes are described. 相似文献
228.
Hydroborations of propargyl chloride, ethyl propiolate, 3-trimethylsilyloxy-1-butyne, 1,1-diethoxy-2-propyne, 1-iodo- and 1-bromo-1-hexyne, and 1-bromo-3-chloro-1-propyne with diisopinocampheylborane 1, followed by dealkylation of the isopinocampheyl groups with acetaldehyde provide the corresponding 1-alkenylboronates in high yields with high regioselectivity. 相似文献
229.
Pd‐initiated polymerization of diazo compounds bearing dialkoxyphosphinyl group and hydrolysis of the resulting polymers and oligomers to afford phosphonic acid‐containing products
下载免费PDF全文
![点击此处可从《Journal of polymer science. Part A, Polymer chemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Hiroaki Shimomoto Akira Oda Motoki Kanayama Tomoya Sako Tomomichi Itoh Eiji Ihara Naohiro Hoshikawa Akihiko Koiwai Naoki Hasegawa 《Journal of polymer science. Part A, Polymer chemistry》2016,54(12):1742-1751
Pd‐initiated polymerization and oligomerization of diazo compounds containing a dialkoxyphosphinyl group are described. Polymerization of 2‐dialkoxyphosphinylethyl diazoacetates with π‐allylPdCl‐based initiating systems afforded C? C main chain polymers bearing phosphonate on each main chain carbon atom. The quantitative transformation of the side chain phosphonate to phosphonic acid resulted in the formation of water soluble polymers having the acid groups accumulated around their main chains, although the carbonyl ester linkage in the side chain was cleaved via intramolecular acid‐assisted hydrolysis in water at 80 °C. Pd‐initiated oligomerization of diethyl diazomethylphosphonate yielded an oligomeric product bearing diethoxyphosphiny groups directly attached to its main chain carbons, with unexpected incorporation of azo group in the main chain framework. Hydrolysis of the phosphonate of the oligomer afforded a water‐soluble product, which was revealed to show higher proton conductivity than poly(vinylphosphonic acid) under certain conditions. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1742–1751 相似文献
230.
A new type of optically active N-(L-menthylcarboxylatomethyl)maleimide (MGMI) was synthesized from maleic anhydride, glycine, and L-menthol. Radical homopolymerization of MGMI was performed at 50°C for 24 h to give optically active polymer having [α]D = -57°. Radical copolymerizations of MGMI (M 1) were performed with styrene (ST, M 2), methyl methacrylate (MMA, M 2) in benzene at 50°C. From the results, the monomer reactivity ratios (r 1, r 2) and the Alfrey-Price Q, e values were determined as follows: r 1 = 0.16, r 2 = 0.006 for the MGMI-ST system; r 1 = 0.15, r 2 = 1.65 for the MGMI-MMA system, and Q 1 = 0.72, e 1 = 1.59 calculated from the MGMI-MMA system. Anionic homopolymerizations of MGMI were also carried out. Chiroptical properties of the polymers were investigated. 相似文献