全文获取类型
收费全文 | 1356篇 |
免费 | 36篇 |
国内免费 | 2篇 |
专业分类
化学 | 912篇 |
晶体学 | 17篇 |
力学 | 20篇 |
数学 | 101篇 |
物理学 | 344篇 |
出版年
2021年 | 15篇 |
2019年 | 18篇 |
2018年 | 14篇 |
2016年 | 18篇 |
2015年 | 26篇 |
2014年 | 30篇 |
2013年 | 59篇 |
2012年 | 50篇 |
2011年 | 62篇 |
2010年 | 39篇 |
2009年 | 38篇 |
2008年 | 56篇 |
2007年 | 55篇 |
2006年 | 55篇 |
2005年 | 61篇 |
2004年 | 52篇 |
2003年 | 42篇 |
2002年 | 53篇 |
2001年 | 28篇 |
2000年 | 21篇 |
1999年 | 20篇 |
1998年 | 20篇 |
1997年 | 17篇 |
1996年 | 17篇 |
1995年 | 14篇 |
1994年 | 20篇 |
1993年 | 18篇 |
1992年 | 30篇 |
1991年 | 14篇 |
1990年 | 10篇 |
1989年 | 16篇 |
1988年 | 16篇 |
1987年 | 14篇 |
1986年 | 18篇 |
1985年 | 14篇 |
1984年 | 27篇 |
1983年 | 18篇 |
1982年 | 19篇 |
1981年 | 23篇 |
1980年 | 17篇 |
1979年 | 22篇 |
1978年 | 10篇 |
1977年 | 17篇 |
1976年 | 19篇 |
1975年 | 25篇 |
1974年 | 20篇 |
1973年 | 18篇 |
1972年 | 18篇 |
1971年 | 10篇 |
1965年 | 12篇 |
排序方式: 共有1394条查询结果,搜索用时 0 毫秒
1.
2.
Yoshitomo Ono Naoyuki Kawashima Hiroto Kudo Tadatomi Nishikubo Takabumi Nagai 《Journal of polymer science. Part A, Polymer chemistry》2007,45(14):2978-2988
The ring‐opening copolymerization of a glycidyl ester derivative having a benzophenone group and the donor–acceptor norbornadiene (D‐A NBD) dicarboxylic acid, 5‐(4‐methoxyphenyl)‐1,4,6,7,7‐pentamethyl‐2,5‐norbornadiene‐2,3‐dicarboxylic acid, monoglycidyl ester derivatives with D‐A NBD dicarboxylic anhydride using tetraphenylphosphonium bromide as a catalyst proceeded smoothly to give novel self‐photosensitizing NBD polymers in good yields. The molecular weight of these polyesters was about 4,000, and lower than that of analogous NBD polymers having no benzophenone group. All the synthesized NBD polymers isomerized smoothly to the corresponding quadricyclane (QC) polymers upon UV irradiation in tetrahydrofuran (THF) solution and in the film state. The rate of the photoisomerization of the D‐A NBD moieties in these polymers was higher than that of the D‐A NBD moieties in the polymer having no photosensitizing group. Furthermore, the rate of the photoisomerization of the D‐A NBD moieties in these polymers was also higher than that of the NBD polymer with low molecular weight photosensitizer in dilute solution. The photo‐irradiated polymers having QC moieties released thermal energies of 146–180 J/g. The D‐A NBD moieties contained in these NBD polymers possessed fair to good fatigue resistance. The degradation of the NBD moieties in these polymers was 15–30% after 50 repeated cycles of interconversion. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2978–2988, 2007 相似文献
3.
Michiko Tamura 《Geometriae Dedicata》1992,42(3):311-315
LetM be a complete smooth surface of constant mean curvature in the Euclidean 3-space. If there exists two helical geodesics onM through each point ofM, thenM is either a plane, a sphere, or a circular cylinder. 相似文献
4.
A relativistic Green function formalism has been applied to calculate layer-projected densities of states on Pd(110). In particular, we obtained unoccupied surface states and their dispersion relations along two directions in the surface Brillouin zone. Good agreement with recent inverse photoemission data is reached by using an energy-dependent dynamical surface potential barrier, which is based on a simple electron-plasmon interaction model, instead of a static surface barrier. 相似文献
5.
Tadao Seguchi Naoyuki Tamura 《Journal of polymer science. Part A, Polymer chemistry》1974,12(9):1953-1964
The regions trapping allyl radicals in irradiated polyethylene and the reactivity of the radicals with various monomers have been studied by electron spin resonance. Most of the allyl radicals are trapped in defects or surfaces of the crystallite, and only 10% of the radicals are trapped inside the crystallites. Since the reactivity of the allyl radicals depends on whether they come in contact with reactive monomers, the rate of reaction is related to the concentration of the monomers. When grafting reactions are initiated by allyl radicals, the rate of initiation is rapid and the rate of termination at the initial stage is also very fast. Consequently the yield of grafting increases at the initial stage but soon levels off, which is in contrast to the grafting behavior with alkyl radicals. 相似文献
6.
An interesting transformation occurs during acylation of 4(R)-hydroxymethyl-3-methyl-1,3-thiazolidine when 4(R)-acylthiomethyl-3-methyl-1,3-oxazolidines are yielded: the reaction competing with O-acylation is controlled by the bulkiness of the acyl group. 相似文献
7.
Y. Sakaiguchi T. Shikata H. Urakami A. Tamura H. Hirata 《Colloid and polymer science》1987,265(8):750-753
Some cationic surfactants such as cetyltrimethylammonium bromide (CTAB) show a very spectacular viscoelasticity in solution, in even very diluted states, with some aromatic substances added, such as salicylic acid. Formerly, the authors established that the remarkable solution behaviour was the result of the entanglement of such enormously elongated giant micelles, based on recognition of the existence of large aggregates, through direct observation of them as substantial images under the electron microscope.In this report, we further confirm the relation between micelle length and solution viscoelasticity after arbitrarily obtaining different size aggregates by altering the media pH, or by admixing shorter chain length surfactants than CTAB, which alone did not induce viscoelasticity. 相似文献
8.
9.
10.