全文获取类型
收费全文 | 514篇 |
免费 | 8篇 |
国内免费 | 1篇 |
专业分类
化学 | 227篇 |
晶体学 | 3篇 |
力学 | 31篇 |
数学 | 69篇 |
物理学 | 193篇 |
出版年
2022年 | 6篇 |
2021年 | 9篇 |
2020年 | 5篇 |
2019年 | 11篇 |
2018年 | 9篇 |
2017年 | 13篇 |
2016年 | 16篇 |
2015年 | 13篇 |
2014年 | 18篇 |
2013年 | 24篇 |
2012年 | 37篇 |
2011年 | 41篇 |
2010年 | 28篇 |
2009年 | 10篇 |
2008年 | 5篇 |
2007年 | 9篇 |
2006年 | 8篇 |
2005年 | 32篇 |
2004年 | 13篇 |
2003年 | 8篇 |
2002年 | 11篇 |
2001年 | 11篇 |
2000年 | 4篇 |
1997年 | 4篇 |
1996年 | 11篇 |
1995年 | 12篇 |
1994年 | 6篇 |
1991年 | 3篇 |
1990年 | 6篇 |
1988年 | 4篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1975年 | 4篇 |
1974年 | 7篇 |
1971年 | 3篇 |
1970年 | 5篇 |
1969年 | 4篇 |
1968年 | 5篇 |
1967年 | 6篇 |
1964年 | 4篇 |
1959年 | 3篇 |
1939年 | 5篇 |
1937年 | 3篇 |
排序方式: 共有523条查询结果,搜索用时 46 毫秒
81.
82.
83.
Subodh Bhatnagar Judith Polonsky Thierry Sevenet Thierry Prangé 《Tetrahedron letters》1985,26(9):1225-1228
The structure of 15-O-benzoyl-brucein D, a new quassinoid isolated from Lam., has been established from spectral data and by single-crystal X-ray analysis ; the previously known picrasin B, isobrucein A and B were also isolated. 相似文献
84.
85.
86.
A liquid membrane comprising 5-10% bis(2,4,4-trimethylpentyl)phosphinic acid in dodecane that is supported between an aqueous sample at pH 4.7-6.0 and a 0.1M HCl receiver results in uphill transport of Zn(II) from the sample into the receiver. With 2 ml of receiver, a 5 cm(2) membrane and 60 min dialysis time, Zn(II) is preconcentrated by a factor of ca. 13 when the initial concentration in the sample is in the range 1.5 x 10(-7)-1.5 x 10(-4)M. The enrichment factor is directly proportional to time up to 30 min since the transport rate of Zn(II) across the membrane is constant over this period. At longer times the flux is slowed as the system begins to approach equilibrium. The presence of other metals such as Cu(II), Co(II), Ni(II), Cd(II), Pb(II) and Fe(II) does not change the enrichment factor for Zn(II), even when the interferent is at a concentration high enough for the rate of transport (nmole/min) of the interferent and Zn(II) to be about the same. The flux of Zn(II) was about 40 times that of Cu(II) and 100 times that of Co(II) when their concentrations in the sample were equal. The other metal ions examined are not significantly transported. 相似文献
87.
88.
89.
P. L. Bhatnagar 《Proceedings Mathematical Sciences》1967,66(6):342-352
This paper compares, in a general way, the predictions of the constitutive equations given by Rivlin and Ericksen, Oldroyd, and Walters. Whether we consider the rotational problems in cylindrical co-ordinates or in spherical polar co-ordinates, the effect of the non-Newtonicity on the secondary flows is collected in a single parameterα which can be explicitly expressed in terms of the non-Newtonian parameters that occur in each of the above-mentioned constitutive equations. Thus, for a given value ofα, all the three fluids will have identical secondary flows. It is only through the study of appropriate normal stresses that a Rivlin-Ericksen fluid can be distinguished from the other two fluids which are indistinguishable as long as this non-Newtonian parameter has the same value. 相似文献
90.