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61.
A. N. Useinov L. R. Tagirov R. G. Deminov Y. Zhou G. Pan 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,60(2):187-192
We investigated the mean-free path effects
on the magnetoresistance of ferromagnetic nanocontacts.
For most combinations of parameters the magnetoresistance
monotonously decreases with increasing the contact cross-section.
However, for a certain choice of parameters the calculations show
non-monotonous behavior of the magnetoresistance
in the region in which the diameter of the contact becomes
comparable with the mean-free path of electrons.
We attribute this effect to different conduction
regimes in the vicinity of the nanocontact: ballistic for electrons of
one spin projection, and simultaneously diffusive for the other.
Furthermore, at certain combinations of spin asymmetries
of the bulk mean-free paths in a heterocontact, the
magnetoresistance can be almost constant,
or may even grow as the contact diameter increases.
Thus, our calculations suggest a way to search
for combinations of material parameters,
for which high magnetoresistances can be achieved
not only at the nanometric size of the contact, but also at much
larger cross-sections of nanocontacts which can be
easier for fabriaction with current technologies.
The trial calculations of the magnetoresistance with material parameters
close to those for the Mumetal-Ni heterocontacts agree satisfactorily
with the available experimental data. 相似文献
62.
The molecule of 4-tricyanovinyl-N,N-diethylaniline is disordered about an axis that is close to the axis passing through the 1,4-carbon atoms. The disorder is a 1:1 type of disorder that involves only part of the molecule as the diethylamino substitutent and the three nitrogen atoms of the tricyanovinyl substituent are ordered. The treatment of the nearly ‘whole-molecule disorder’ by employing a small number of restraints is described. Crystal data: C15H14N4, triclinic, P , a = 7.1996(5), b = 7.7232(5), c = 12.4171(8) , α = 99.350(1), β = 94.647(1), γ = 103.312(1)o and V = 657.90(8) 3 at –173 K. 相似文献
63.
Let k, m be two positive integers with m ≤ k and let F be a family of zero-free meromorphic functions in a domain D, let h(z) ≡ 0 be a meromorphic function in D with all poles of h has multiplicity at most m. If, for each f ∈ F, f(k)(z) = h(z) has at most k- m distinct roots(ignoring multiplicity) in D, then F is normal in D. This extends the results due to Chang[1], Gu[3], Yang[11]and Deng[1]etc. 相似文献
64.
CHEN Fei LI Zhe YANG Shuo WANG Rui-jian LIU Bin SONG Yu-ming SUN Yan-hong HAO Dong-yun NG Xlao-ping 《高等学校化学研究》2008,24(4):491-495
To overcome ampicillin-resistance of bacteria which is believed to attribute their endogenous B-lactamase, we designed three 10-23 DNAzymes(Dz1, Dz2. Dz3) targeting the coding region of B-lactamase mRNA and examined their inhibitory capabilities of the ampicillin-resistance of TEM-1 and TEM-3 bacteria. Dz1 was a traditional 10-23 DNAzyme, Dz2 was the mutant of Dz1 by addition of the protected nucleotide to each ann of the enzyme, and Dz3 was a mutant of Dz1 at antisense arms of which phosphorothioate modifications were made. Kinetic analysis, bacterial growth, and β-lactamase activity measurement showed that all the three DNAzymes worked efficiently in vitro and in vivo. A 9 hours bacterial growth inhibition test showed that the inhibition rates of TEM-1 bacteria by Dz1, Dz2, and Dz3 were 27%, 50%, and 29%, respectively. In addition, the inhibition rates of TEM-3 bacteria by those three DNAzymes were found io be 49%, 58%, and 45%, respectively. The current findings suggest that DNAzymes may become potential candidates of alternative inhibitors for bacteria drug-resistance. 相似文献