全文获取类型
收费全文 | 1036篇 |
免费 | 17篇 |
国内免费 | 5篇 |
专业分类
化学 | 706篇 |
晶体学 | 11篇 |
力学 | 48篇 |
数学 | 47篇 |
物理学 | 246篇 |
出版年
2021年 | 12篇 |
2020年 | 9篇 |
2019年 | 12篇 |
2018年 | 10篇 |
2017年 | 13篇 |
2016年 | 12篇 |
2015年 | 15篇 |
2014年 | 27篇 |
2013年 | 47篇 |
2012年 | 55篇 |
2011年 | 39篇 |
2010年 | 23篇 |
2009年 | 36篇 |
2008年 | 51篇 |
2007年 | 65篇 |
2006年 | 47篇 |
2005年 | 49篇 |
2004年 | 46篇 |
2003年 | 39篇 |
2002年 | 59篇 |
2001年 | 24篇 |
2000年 | 29篇 |
1999年 | 13篇 |
1998年 | 13篇 |
1997年 | 10篇 |
1996年 | 8篇 |
1995年 | 11篇 |
1994年 | 12篇 |
1993年 | 11篇 |
1992年 | 16篇 |
1991年 | 14篇 |
1990年 | 13篇 |
1989年 | 12篇 |
1988年 | 15篇 |
1987年 | 13篇 |
1986年 | 10篇 |
1985年 | 10篇 |
1984年 | 15篇 |
1983年 | 10篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1979年 | 15篇 |
1978年 | 18篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 8篇 |
1974年 | 6篇 |
1972年 | 5篇 |
1967年 | 12篇 |
排序方式: 共有1058条查询结果,搜索用时 78 毫秒
991.
Ohne Zusammenfassung 相似文献
992.
993.
994.
Summary Construction of small data base in the area of liquid chromaography for inorganic compounds is described. A 16-bit microcomputer is used and several types of conversational retrieval systems are demonstrated. 相似文献
995.
T. Miki T. Higashimura S. Okamura 《Journal of polymer science. Part A, Polymer chemistry》1968,6(11):3031-3040
The polymerization of trioxane catalyzed by stannic chloride (SnCl4) in ethylene dichloride was studied and compared with the results obtained with boron trifluoride etherate, BF3·O(C2H5)2, as catalyst. Under the same conditions, the polymerization rate was larger with SnCl4 than with BF3·O(C2H5)2, while at a fixed polymer yield the molecular weight of the polymer obtained by SnCl4 was lower than with the BF3·O(C2H5)2 catalyzed reaction. The overall activation energy of trioxane polymerization with SnCl4 was 11.0 ± 0.8 kcal/mole. The kinetic orders of catalyst and monomer were determined to be close to 2 and 4, respectively. A certain amount of tetraoxane was also produced in an early stage of the polymerization with SnCl4 similar to BF3·O(C2H5)2-catalyzed reaction. However, the maximum amount of tetraoxane produced at 30°C was larger with SnCl4 than with BF3·O(C2H5)2. In addition, a ten-membered ring compound (pentoxane) was isolated in the solution polymerization of trioxane catalyzed by both SnCl4 and BF3·O(C2H5)2. The confirmation of pentoxane formation is strong evidence for the back-biting reaction mechanism. 相似文献
996.
997.
Differential cross sections of proton Compton scattering in the energy range between 450 and 950 MeV
K. Toshioka M. Chiba S. Kato K. Sugano K. Ukai T. Shimomura T. Shinohara M. Daigo Y. Hemmi R. Kikuchi M. Minowa K. Miyake T. Nakamura A. Noda M. Ono Y. Suzuki M. Yoshioka Y. Hoshi 《Nuclear Physics B》1978,141(4):364-378
The differential cross sections of the proton Compton scattering around the second resonance have been measured at a c.m. angle of 90° for incident photon energies between 450 MeV and 950 MeV in steps of 50 MeV, and at an angle of 60° for energies between 600 MeV and 800 MeV. The results show that the peak of the 2nd resonance agrees with that of the pion photoproduction process. We also calculated the proton Compton scattering based on unitarity and fixed-t dispersion relations. The calculation describes well the data of the cross section and the recoil proton polarization. 相似文献
998.
Ichiro Noda Toshiaki Kitano Mitsuru Nagasawa 《Journal of Polymer Science.Polymer Physics》1977,15(7):1129-1142
The effect of molecular weight heterogeneity on the second virial coefficient A2 in good solvents is studied for binary mixtures of monodisperse poly(α-methylstyrenes). It is concluded that A2 for polymer mixtures passes through a maximum with variation of the mixing ration. From comparison with the data, it is concluded that no available theory quantitatively explains both the molecular weight dependence of A2 of monodisperse polymer and the variation of A2 of mixtures with the mixing ratio. The interpenetration function for two polymer coils with different molecular weights is discussed on the assumption that the thermodynamic interaction between two polymer coils in good solvents can be approximated by a hard-sphere model. 相似文献
999.
Kokichi Tanaka Shinichi Tamura Shigehiko Miki Kazumasa Ozawa 《Optics Communications》1976,16(2):226-229
The results of experiments on character recognition, using a combination of Φ-spatial and band-pass filters, are reported. The experiments were made with fifteen classes of typewritten characters, with twenty-four classes of typewritten characters and with ten classes of handwritten characters. 相似文献
1000.