全文获取类型
收费全文 | 930篇 |
免费 | 167篇 |
国内免费 | 194篇 |
专业分类
化学 | 983篇 |
晶体学 | 37篇 |
力学 | 27篇 |
综合类 | 5篇 |
数学 | 1篇 |
物理学 | 238篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 15篇 |
2021年 | 20篇 |
2020年 | 39篇 |
2019年 | 24篇 |
2018年 | 19篇 |
2017年 | 27篇 |
2016年 | 41篇 |
2015年 | 34篇 |
2014年 | 46篇 |
2013年 | 91篇 |
2012年 | 64篇 |
2011年 | 55篇 |
2010年 | 57篇 |
2009年 | 45篇 |
2008年 | 61篇 |
2007年 | 66篇 |
2006年 | 61篇 |
2005年 | 60篇 |
2004年 | 62篇 |
2003年 | 53篇 |
2002年 | 51篇 |
2001年 | 21篇 |
2000年 | 30篇 |
1999年 | 30篇 |
1998年 | 30篇 |
1997年 | 24篇 |
1996年 | 31篇 |
1995年 | 27篇 |
1994年 | 6篇 |
1993年 | 14篇 |
1992年 | 25篇 |
1991年 | 12篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 2篇 |
1987年 | 6篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1974年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有1291条查询结果,搜索用时 15 毫秒
91.
92.
93.
A.G. Cairns J.S.J. Hargreaves D. Mckay K. Wilson 《Journal of solid state chemistry》2010,183(3):613-61
The addition of 1 wt% Pd, Au, Ni and Cu dopants has been demonstrated to strongly alter the morphology of beta-phase molybdenum nitride prepared by treatment of MoO3 with a 3/1 H2/N2 mixture at 750 °C. Furthermore, the addition of Pd significantly enhances the surface area and the formation of the nitride phase. It is proposed that the facile formation of molybdenum bronzes in this system is important in this respect. The dopants have also been observed to modify the denitridation characteristics of the beta-phase, with an overall reduction of the proportion of NH3 formed upon using a 3/1 H2/Ar mixture with respect to the undoped sample. 相似文献
94.
B. Goldstein 《辐射效应与固体损伤》2013,168(3-4):229-237
Single crystal silicon, both with and without oxygen, has been diffused with lithium to concentrations ~1017/cm2, irradiated with 1 to 1.5 MeV electrons, and the ensuing defects studies by EPR measurements. The presence of oxygen strongly affects the properties of these defects. Measurements have indicated the presence of two new defects which involve Li-one in O-containing material and one in O-free material. The defects are observed in their electron-filled state, and indicate a net electron spinof ½. The defect spectra disappear (with time) at room temperature, and can be explained by the formation of other Li-involved defects which lie deeper in the energy bandgap and are not visible by EPR. Electron irradiation at 40 °K followed by annealing at higher temperatures show that both EPR defects described above begin to form at about 200 °K and begin to decrease at about 275 °K-just as does the 250 °K reverse annealing observed generally for n-type Si. Based on these data, and the work of others, it is suggested that both defects form as a result of the motion of Si interstitials which produce a (Li-O-interstitial) complex in O-containing Si, and a (Li-interstitial) complex in O-free Si. 相似文献
95.
This paper gives the general expressions for the compliance s′ijkl, Young's modulus E(hkl) and Poisson's ratio v(hkl, θ) along arbitrary loading direction [hkl] for tetragonal crystals. The representation surface for which the length of the radius vector in the [hkl] direction equals E(hkl) and representation curve for which the length of the radius vector with angle θ deviated from the reference directions [001^-], [100], [001^-], [101^-] and [112^-] equals v(100, θ), v(001, θ), v(110,θ), v(101,θ) and v(111, θ) respectively, are constructed for nine tetragonal crystals (ammonium dihydrogen arsenate, ammonium dihydrogen phosphate, barium titanate, indium, nickel sulfate, potassium dihydrogen arsenate, potassium dihydrogen phosphate, tin and zircon). The characteristics of them are analysed in detail. 相似文献
96.
The Self Consistent Modified Extended Hückel molecular orbital method had been applied to several square planar complexes of platinum (II). Calculations including both the limited 5d, 6s, 6p and extended 5s, 5p, 5d, 6s, 6p starting bases for platinum were made. It is shown that in PtCl
4
2–
both the nuclear quadrupole moment and minimum total energy vs. bond distance are calculated to be in good agreement with experiment, only with the extended platinum AO basis.Specific inclusion of relativistic parameters via a pseudo-relativistic approximation are shown to have a significant effect on the energy molecular energy levels, however no meaningful rationalization can be made without the simultaneous inclusion of ligand field parameters as well.Supported in part by a grant made available through the Cancer Association of Greater New Orleans. Use of the facilities of the Computer Research Center of the University of New Orleans is gratefully acknowledged. 相似文献
97.
98.
99.
100.