全文获取类型
收费全文 | 96篇 |
免费 | 9篇 |
国内免费 | 9篇 |
专业分类
化学 | 64篇 |
晶体学 | 2篇 |
力学 | 4篇 |
综合类 | 1篇 |
数学 | 33篇 |
物理学 | 10篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 1篇 |
2019年 | 6篇 |
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 3篇 |
2014年 | 7篇 |
2013年 | 5篇 |
2012年 | 12篇 |
2011年 | 6篇 |
2010年 | 8篇 |
2009年 | 2篇 |
2008年 | 9篇 |
2007年 | 10篇 |
2006年 | 2篇 |
2005年 | 6篇 |
2004年 | 3篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1991年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有114条查询结果,搜索用时 15 毫秒
11.
考虑了二维空间上具超音速物理边界的可压Navier-Stokes方程的初边值问题.给定常数平衡态(ρ~*,0),得到了所考虑问题解的整体存在性.在平衡态附近的小扰动下,利用加权能量估计方法得到解的指数衰减性. 相似文献
12.
13.
In this paper Green’s functions for the Boltzmann equation around a global Maxwellian are used to construct the non-characteristic
nonlinear Knudsen layers as well as their time-asymptotic stability. Furthermore, the detailed pointwise structures, nonlinear
wave couplings, and wave interactions with boundary are studied. 相似文献
14.
Via a catalytic cycle in the presence of scandium triflate (2 mol %)/DMF (1 mol %)/benzoyl chloride (5 mol %), aromatic ketones were treated with bis(trichloromethyl) carbonate (BTC) to afford aryl-(Z)-vinyl chlorides. All metal triflates tested in the reaction showed highly catalytic activity. A plausible addition-elimination mechanism was proposed. The present work describes the first catalytic and green route to the synthesis of aryl-(Z)-vinyl chlorides. [reaction: see text] 相似文献
15.
Qin C Wu H Cheng J Chen X Liu M Zhang W Su W Ding J 《The Journal of organic chemistry》2007,72(11):4102-4107
Reaction of aryl- or heteroarylboronic acids with aldehydes, in the presence of PdCl2 and P(1-Nap)3, afforded carbinol derivatives in good to excellent yields. The efficiency of this reaction was demonstrated by the compatibility with nitro, cyano, acetamido, acetoxy, acetyl, carboxyl, trifluoromethyl, fluoro, and chloro groups and the possibility of involving aliphatic aldehyde or hindered substrates. Moreover, the rigorous exclusion of air/moisture is not required in these transformations. 相似文献
16.
Gallium(III) triflate-catalyzed ring opening of epoxides affords beta-hydroxy sulfides with high regioselectivity and chemoselectivity in high yields (84-97%) under solvent-free conditions. Additionally, a simple, efficient, and environmentally benign one-pot procedure for the synthesis of beta-hydroxy sulfoxides in sole water has been developed for the first time. The process, promoted by a H2O2-Ga(OTf)3 system, affords beta-hydroxy sulfoxides in high yields (81-94%) and high chemoselectivity without any detectable overoxidation to beta-hydroxy sulfones. The catalyst could be recovered easily after the reactions and reused without evident loss of activity. 相似文献
17.
Wang Weike 《偏微分方程(英文版)》1991,4(4)
We consider a solution of the semi-linear partial differential equations in higher space dimensions. We show that if there exist two characteristic hypersurface bearing different weak singularities intersect transversally, and another one characteristic hypersurface issues from above intersection, then the solution would be conormal with respect to the union of these surfaces, and satisfy the so-called “sum law”. 相似文献
18.
19.
Analyzing the flow field distributions around a near-space blunt-cone vehicle at different flight speeds, we observe that, when the flight speed exceeds a certain threshold, the relationship between the flow field density and the vehicle speed presents a characteristic opposite to that at the flight condition of the speed lower than the threshold. On this basis, the Runge–Kutta method is applied to solve the ray equations in non-uniform plasma, in which the electron density at any computing point is obtained by the Lagrange interpolation based on the discrete data of the flow field. Then the EM wave attenuation in the sheath is determined by the subsection integral method combining with the electromagnetic theory. The numerical results also show that when the flight velocity is lower than the threshold, the energy transfer efficiency of the EM waves decreases with the increase of the vehicle velocity. However, when the flight speed is greater than the threshold, the energy transfer efficiency increases as the vehicle speed increases. This conclusion will be helpful to further understand the EM wave propagation characteristics for hypersonic vehicles, and to provide a reference for the channel selection of antennas. 相似文献
20.