全文获取类型
收费全文 | 196篇 |
免费 | 4篇 |
国内免费 | 3篇 |
专业分类
化学 | 76篇 |
晶体学 | 4篇 |
力学 | 33篇 |
数学 | 48篇 |
物理学 | 42篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 9篇 |
2017年 | 4篇 |
2016年 | 10篇 |
2015年 | 11篇 |
2014年 | 15篇 |
2013年 | 25篇 |
2012年 | 19篇 |
2011年 | 16篇 |
2010年 | 12篇 |
2009年 | 8篇 |
2008年 | 11篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1994年 | 1篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 2篇 |
排序方式: 共有203条查询结果,搜索用时 15 毫秒
31.
32.
Siamak Yassemi 《Czechoslovak Mathematical Journal》1997,47(4):585-592
It is shown that for any Artinian modules M, M
is the greatest integer i such that
(M
) 0. 相似文献
33.
Maryam Ataeefard Siamak Moradian Mojtaba Mirabedini Morteza Ebrahimi Saeed Asiaban 《Plasma Chemistry and Plasma Processing》2008,28(3):377-390
The surface of a LDPE was modified by Ar, O2, N2, CO2 gaseous plasma. The changes in surface morphology and surface wettability were investigated using AFM and SEM. The surface
chemical changes of LDPE were also characterized by FTIR-ATR. The SEM and AFM results demonstrated variable changes in surface
roughness for different types of plasma gas used, the changes being more for the Ar and N2 plasma treatments. Considering the nature of the LDPE film, XRD studies were carried out to determine changes in the percentage
crystalinity. The results showed that all low pressure O2, Ar, N2, CO2 gas plasmas improved the wettability of LDPE films. Contact angles decreased significantly depending on the discharge powers
and exposure times. Surface morphology was also found to vary with plasma discharge powers, exposure times, and the type of
gas being used. Ar and N2 gas plasmas in general produced more superior results. 相似文献
34.
By calculating the energies of neutral and different ionic forms (M2+, M+, M, M-, and M2-) of 32 elements (using B3LYP/6-311++G** level of theory) and taking energy (E) to be a Morse-like function of the number of electrons (N), the electrophilicity values (omega) are calculated for these atoms. The obtained electrophilicities show a good linearity with some commonly used electronegativity scales such as Pauling and Allred-Rochow. Using these electrophilicities, the ionicities of some diatomic molecules are calculated, which are in good agreement with the experimental data. Therefore, these electrophilicities are introduced as a new scale for atomic electronegativity, chi(omega)0. The same procedure is also performed for some simple polyatomic molecules. It is shown that the new scale successfully obeys Sanderson's electronegativity equalization principle and for those molecules which have the same number of atoms, the ratio of the change in electronegativity during the formation of a molecule from its elements to the molecular electronegativity (Delta chi/chi omega) is the same. 相似文献
35.
Let be a commutative Noetherian local ring and let be an ideal of R. We give some inequalities between the Bass numbers of an R–module and those of its local cohomology modules with respect to . As an application of these inequalities, we recover results of Delfino-Marley and Kawasaki by showing that for a minimax
R-module M and for any non-negative integer i, the Bass numbers of the ith local cohomology module are finite if one of the following holds:
S. Yassemi was supported by a grant from IPM No. 85130214. 相似文献
(a) | , |
(b) | is a principal ideal. |
36.
37.
Proppants transport is an advanced technique to improve the hydraulic fracture phenomenon,in order to promote the versatility of gas/oil reservoirs.A numerical ... 相似文献
38.
Amin Heshmati-Moulai Hamidreza Simchi Mahdi Esmaeilzadeh 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(7):128
We study perfect valley polarization in a molybdenum disulfide (MoS2) nanoribbon monolayer using two bands Hamiltonian model and non-equilibrium Green’s function method. The device consists of a one-dimensional quantum wire of MoS2 monolayer sandwiched between two zigzag MoS2 nanoribbons such that the sites A and B of the honeycomb lattice are constructed by the molecular orbital of Mo atoms, only. Spin-valley coupling is seen in energy dispersion curve due to the inversion asymmetry and time-reversal symmetry. Although, the time reversal symmetry is broken by applying an external magnetic field, the valley polarization is very small. A valley polarization equal to 46% can be achieved using an exchange field of 0.13 eV. It is shown that a particular spin-valley combination with perfect valley polarization can be selected based on a given set of exchange field and gate voltage as input parameters. Therefore, the valley polarization can be detected by detecting the spin degree of freedom. 相似文献
39.
Let ${(R, \mathfrak{m})}$ be a commutative Noetherian local ring of Krull dimension d, and let C be a semidualizing R-module. In this paper, it is shown that if R is complete, then C is a dualizing module if and only if the top local cohomology module of ${R, H _{\mathfrak{m}} ^{d} (R)}$ , has finite G C -injective dimension. This generalizes a recent result due to Yoshizawa, where the ring is assumed to be complete Cohen-Macaulay. 相似文献
40.
Let R be a commutative Noetherian ring. It is shown that the finitely generated R-module M with finite Gorenstein dimension is reflexive if and only if M p is reflexive for p ∈ Spec(R) with depth(R p) ? 1, and $G - {\dim _{{R_p}}}$ (M p) ? depth(R p) ? 2 for p ∈ Spec(R) with depth(R p) ? 2. This gives a generalization of Serre and Samuel’s results on reflexive modules over a regular local ring and a generalization of a recent result due to Belshoff. In addition, for n ? 2 we give a characterization of n-Gorenstein rings via Gorenstein dimension of the dual of modules. Finally it is shown that every R-module has a k-torsionless cover provided R is a k-Gorenstein ring. 相似文献