全文获取类型
收费全文 | 666篇 |
免费 | 23篇 |
学科分类
数理化 | 689篇 |
出版年
2021年 | 8篇 |
2020年 | 9篇 |
2019年 | 15篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 16篇 |
2015年 | 11篇 |
2014年 | 10篇 |
2013年 | 25篇 |
2012年 | 44篇 |
2011年 | 29篇 |
2010年 | 17篇 |
2009年 | 17篇 |
2008年 | 34篇 |
2007年 | 31篇 |
2006年 | 40篇 |
2005年 | 31篇 |
2004年 | 32篇 |
2003年 | 23篇 |
2002年 | 18篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1997年 | 8篇 |
1996年 | 11篇 |
1995年 | 6篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1991年 | 5篇 |
1990年 | 9篇 |
1989年 | 12篇 |
1988年 | 11篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 10篇 |
1984年 | 21篇 |
1983年 | 6篇 |
1982年 | 13篇 |
1981年 | 12篇 |
1980年 | 8篇 |
1979年 | 13篇 |
1978年 | 15篇 |
1977年 | 9篇 |
1976年 | 8篇 |
1975年 | 9篇 |
1974年 | 11篇 |
1973年 | 15篇 |
1970年 | 2篇 |
1967年 | 2篇 |
排序方式: 共有689条查询结果,搜索用时 15 毫秒
101.
Sadao Nakajima Kyoko Kosasa Yoshio Maruyama Seichi Kawai 《Spectrochimica Acta Part B: Atomic Spectroscopy》1982,37(8):685-690
The behavior of powdered samples in the region behind the incident and reflected shock wave were investigated. When the particle size is less than 8 μm, the powdered samples are effectively vaporized and excited to emit spectral lines. It was shown that the sample particles are scattered behind the incident wave and concentrated again in a narrow portion near the observation window by the use of a reflector so that intense emission can be attained. As an excitation source, the shock tube was used for the determination of trace metals contained in copper oxide. 相似文献
102.
103.
104.
Two kinds of the homogeneous nucleation theory exist at the present: the classical nucleation theory and the semiphenomenological model. To test them, we performed molecular-dynamics (MD) simulations of nucleation from vapor to liquid with 5000-20,000 Lennard-Jones-type molecules. Simulations were done for various values of supersaturation ratios (from 2 to 10) and temperatures (from 80 to 120 K). We compared the size distribution of clusters in MD simulations with those in the theoretical models because the number density of critical clusters governs the nucleation rate. We found that the semiphenomenological model achieves excellent agreements in size distributions of the clusters with all MD simulations we done. The classical theory underestimates the number density of the clusters in the temperature range of 80-100 K, but overestimates in 100-120 K. The semiphenomenological model also predicts well the nucleation rate in MD simulations, while the classical nucleation theory does not. Our results confirmed the validity of the semiphenomenological model for Lennard-Jones-type molecules. 相似文献
105.
106.
107.
108.
Yoshikawa M Kawamura K Ejima A Aoki T Sakurai S Hayashi K Watanabe K 《Macromolecular bioscience》2006,6(3):210-215
Novel molecular recognition materials were prepared from water soluble proteins from thermophile G. thermodenitrificans DSM465 by an alternative molecular imprinting method. Water soluble proteins from G. thermodenitrificans DSM465 were converted into the molecularly imprinted materials by adopting 9-EA as a print molecule. The molecularly imprinted protein membranes recognized As in preference to Gs. The adsorption isotherms led to the conclusion that molecular recognition sites toward As were constructed by the presence of 9-EA during the membrane preparation process. The affinity constant between As and the molecular recognition site thus constructed was determined to be 1.75 x 10(5) mol(-1) dm(3). The results obtained in the present study suggest that water soluble proteins from G. thermodenitrificans DSM465 is one of environmentally-friendly 'green' polymers to be converted into molecular recognition materials by applying an alternative molecular imprinting method. 相似文献
109.
The intermolecular partial wave expansion of the atom-atom potential U is reviewed briefly and developed, by using results due to Sack, so that the radial components of the expansion can be evaluated to arbitrary accuracy for all relevant partial wave orders and values of the intermolecular distance r. These results are used to study the convergence of the partial wave expansion of U as a function of partial wave order, r, intermolecular orientation, and the anisotropy of the interacting molecules. In marked contrast to previous work it is found that many of the higher order partial wave components of U are important relative to the isotropic term even for the interaction of relatively spherical molecules and that the results obtained from a truncated partial wave expansion depend significantly upon the method of summation due to the generally poor convergence of the expansion. The validity of the atom-atom potential as a representation of the correct attractive intermolecular potential is also discussed in some detail. There are basic problems associated with the representations furnished by both the isotropic and the anisotropic parts of the atom-atom potential at intermediate and large r. The different convergence properties of the r -1 expansions of the partial wave expansions of U and of the correct potential for these values of r is illustrated by using model interactions. While it appears that it may be possible to obtain a qualitatively reasonable representation of the attractive part of an intermolecular potential over a useful range of r from atom-atom results, this apparently cannot be achieved for wider ranges of r or for the purely anisotropic part of the potential. 相似文献
110.
According to one suggested model, bending of a single crystal introduces edge dislocations of the same sign. In the present study, this model is examined by computer simulation using molecular dynamics. When a notch is present on the tension surface, Heidenreich-Shockley partial dislocations are created near the tip of the notch. In the compression surface, partial dislocations are created due to wrinkling of the crystal plane. The results of simulation shows that dislocations are more easily created in a compressive bending region than in a tension bending region or simple tension region. 相似文献