全文获取类型
收费全文 | 762篇 |
免费 | 17篇 |
国内免费 | 4篇 |
专业分类
化学 | 510篇 |
晶体学 | 7篇 |
力学 | 37篇 |
数学 | 62篇 |
物理学 | 167篇 |
出版年
2020年 | 10篇 |
2019年 | 9篇 |
2018年 | 6篇 |
2016年 | 15篇 |
2015年 | 11篇 |
2014年 | 9篇 |
2013年 | 27篇 |
2012年 | 38篇 |
2011年 | 28篇 |
2010年 | 20篇 |
2009年 | 11篇 |
2008年 | 44篇 |
2007年 | 45篇 |
2006年 | 50篇 |
2005年 | 41篇 |
2004年 | 42篇 |
2003年 | 29篇 |
2002年 | 27篇 |
2001年 | 15篇 |
2000年 | 18篇 |
1999年 | 17篇 |
1998年 | 13篇 |
1997年 | 5篇 |
1996年 | 14篇 |
1995年 | 7篇 |
1994年 | 12篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1990年 | 7篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1986年 | 5篇 |
1985年 | 11篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1979年 | 9篇 |
1978年 | 4篇 |
1977年 | 12篇 |
1976年 | 6篇 |
1975年 | 13篇 |
1974年 | 8篇 |
1973年 | 10篇 |
1972年 | 6篇 |
1970年 | 5篇 |
1968年 | 10篇 |
1967年 | 4篇 |
1966年 | 4篇 |
1965年 | 4篇 |
排序方式: 共有783条查询结果,搜索用时 46 毫秒
661.
D.B. Jenkins G. Watkin D.P. Wareing G.H.C. Freeman P.H.G. Dickinson D.J. Mackinnon 《Journal of Quantitative Spectroscopy & Radiative Transfer》1985,34(2):123-132
Line profiles of the 130-nm OI(3P-3S) resonance triplet emitted by r.f. excited helium/ oxygen lamps have been resolved using a photoelectric echelle spectrometer. These profiles have been reproduced using a self-absorbed double-Gaussian spectral distribution in which the relative amplitudes of the Gaussian components are functions of the oxygen and helium partial pressures in the lamps. Reasons for the form of the observed spectral distribution are suggested and the importance of the spectrometer measurements to studies of atomic oxygen in the upper atmosphere involving this type of lamp illustrated. 相似文献
662.
Using the principles of the quasi-equilibrium theory, substituent effects, deuterium labeling and comparison of compound behavior, we provide strong evidence for aryl participation in the expalsion of Br· from the molecular ion of β-phenylethyl bromide and eleven of its ringsubstitued derivatives. This reaction shows a kinetic behavior which is typical of rearrangements, its activation energy is lower than that of similar reactions where participation is partially or completely precluded and substitute effects are not only consistent with a particular process, but are also consistent with those predicted from solution chemistry. 相似文献
663.
664.
D.B. Jenkins D.P. Wareing 《Journal of Quantitative Spectroscopy & Radiative Transfer》1985,34(3):271-273
Line profiles of the 130-nm OI (3P-3S) resonance triplet emitted in an off-axis direction by radio-frequency excited helium/oxygen lamps have been investigated using a line-absorption technique. The lamps concerned are of a type widely used in studies of the upper-atmospheric atomic-oxygen distribution. Resonance radiation emitted off-axis by these lamps is found to be more strong absorbed by than that emitted on-axis, in a manner consistent with (a) a self-absorbed double-Gaussian spectral distribution model developed previously and (b) simple geometric considerations. Attention is drawn to potential difficulties in the interpretation of upper-atmospheric atomic-oxygen measurements if an appreciable amount of off-axis radiation from these lamps is employed. 相似文献
665.
Computations are reported which enable the prediction of the necessary truncation of the Bertaut series for various charge density functions consistent with various degrees of convergence. The results are sufficiently extensive to be applicable to almost all lattices. 相似文献
666.
Experimental Techniques - 相似文献
667.
A procedure is outlined for deciding the mix of price and variable non-price features, such as quality, delivery, service or financing, to be included in a bid. The level of each non-price feature is set independently by comparing incremental spending against the alternative price reduction and basing the choice on value to the faction in the customer organization expected to dominate in the choice of the successful bid. Divergence from competition on all non-price features, both fixed and variable, is then taken into account in setting price by calculating a net price equivalent of feature differences as against each competitor. For any given markup the probability of success against a competitor over whom there is a net advantage is the same as that for an equivalently lower markup were price to be the sole basis for allocating the order. 相似文献
668.
669.
670.
T. O. Craig R. M. Quick T. E. Jenkins 《Journal of polymer science. Part A, Polymer chemistry》1977,15(2):441-444
An improved Coulter Counter procedure is described for determining the size distribution and volume fraction of the elastomeric discrete phase in high-impact polystyrene. The method isolates the discrete phase from a dispersion of the whole polymer in DMF by centrifugation and redisperses the discrete phase in an aqueous surfactant solution, thus allowing the particles to deswell and resume the dimensions they had in the polystyrene matrix. By measuring a Coulter Counter size distribution on the aqueous dispersion, a discrete-phase volume fraction can be reliably derived for the original impact polystyrene. The method is rapid and precise. 相似文献