全文获取类型
收费全文 | 309篇 |
免费 | 0篇 |
专业分类
化学 | 141篇 |
晶体学 | 11篇 |
力学 | 1篇 |
数学 | 9篇 |
物理学 | 147篇 |
出版年
2023年 | 2篇 |
2021年 | 3篇 |
2020年 | 8篇 |
2019年 | 5篇 |
2018年 | 3篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 12篇 |
2012年 | 10篇 |
2011年 | 13篇 |
2010年 | 6篇 |
2009年 | 9篇 |
2008年 | 6篇 |
2007年 | 12篇 |
2006年 | 12篇 |
2005年 | 13篇 |
2004年 | 9篇 |
2003年 | 8篇 |
2002年 | 11篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1999年 | 15篇 |
1998年 | 8篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 12篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 10篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1977年 | 7篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1971年 | 5篇 |
1955年 | 2篇 |
1954年 | 2篇 |
排序方式: 共有309条查询结果,搜索用时 15 毫秒
31.
Temporins are short (10–13 amino acids) and linear antimicrobial peptides first isolated from the skin of the European red
frog, Rana temporaria, and are effective against Gram-positive bacteria and Candida albicans. Similarly to other antimicrobial peptides, the association of temporins to lipid membranes has been concluded to underlie
their antimicrobial effects. Accordingly, a detailed understanding of their interactions with phospholipids is needed. We
conjugated a fluorophore (Texas Red) to a Cys containing derivative of temporin B (temB) and investigated its binding to liposomes
by fluorescence spectroscopy. Circular dichroic spectra for the Cys-mutant recorded in the absence and in the presence of
phospholipids were essentially similar to those for temB. A blue shift in the emission spectra and diminished quenching by
ferrocyanide (FCN) of Texas Red labeled temporin B (TRC-temB) were seen in the presence of liposomes. Both of these changes
can be attributed to the insertion of the Texas Red into the hydrophobic region of the bilayer. Resonance energy transfer,
steady state anisotropy, and fluorescence lifetimes further demonstrate the interaction of TRC-temB with liposomes to be enhanced
by negatively charged phospholipids. Instead, cholesterol attenuates the association of TRC-temB with membranes. The interactions
between TRC-temB and liposomes of varying negative surface charge are driven by electrostatics as well as hydrophobicity.
Similarly to native temporin B also TRC-temB forms amyloid type fibers in the presence of negatively charged liposomes. This
property is likely to relate to the cytotoxic activity of this peptide. 相似文献
32.
Surajit Saha Surjeet Singh R. Suryanarayanan A.K. Sood 《Journal of solid state chemistry》2011,184(8):2204-2208
Here we report a temperature-dependent Raman study of the pyrochlore “dynamic spin-ice” compound Pr2Sn2O7 and compare the results with its non-pyrochlore (monoclinic) counterpart Pr2Ti2O7. In addition to phonon modes, we observe two bands associated with electronic Raman scattering involving crystal field transitions in Pr2Sn2O7 at ∼135 and 460 cm−1 which couple strongly to phonons. Anomalous temperature dependence of phonon frequencies that are observed in pyrochlore Pr2Sn2O7 are absent in monoclinic Pr2Ti2O7. This, therefore, confirms that the strong phonon-phonon anharmonic interactions, responsible for the temperature-dependent anomalous behavior of phonons, arise due to the inherent vacant sites in the pyrochlore structure. 相似文献
33.
Raymond K. Sheline B. Singh P. C. Sood S. Y. Chu 《Czechoslovak Journal of Physics》1999,49(7):1047-1066
Energies of the first 2+, 3− and 4+ states of even-even nuclei are plotted against proton and neutron number. Using this systematics, shell effects and the corresponding
quadrupole and hexadecapole collectivity and deformation effects are compared and contrasted. Also, the correspondingB(E2),B(E3) andB(E4) values are plotted against neutron number and their very different systematics compared. Among the new results are the
presence of hexadecapole collectivity at the 82 proton and neutron closed shells and the presence of the maximum values ofB(E4) at neutron numbers 10, 90–92 and 140–146. Finally, the systematics of the hexadecapole (K=4+) vibrations is compared with that of the quadrupole (K=2+) gamma vibrations in the quadrupole deformed rare earth region.
This research has been supported by the National Sciences and Engineering Research Council of Canada at McMaster University
and by the Department of Atomic Energy, Government of India, at Banaras Hindu University. 相似文献
34.
The total attenuation cross-sections in elements 6?Z?82 forK α andK β groups of lines of elements Zr, Sn and Ba andL l ,L α,L β andL γ groups of lines of the elements Au, Pb, Th and U have been measured. The experimentally measured attenuation cross-sections have been found in good agreement with the theoretical estimates. 相似文献
35.
D. D. Sood 《Journal of Sol-Gel Science and Technology》2011,59(3):404-416
The paper reviews the sol–gel methods used for the preparation of nuclear fuel materials in the form of microspheres. It also
discusses how these microspheres can be fabricated into nuclear fuels for reactors such as High Temperature Gas Cooled Reactors
and Fast Reactors. The performance of these microsphere-based fuels is reviewed. More recent applications, such as the transmutation
of minor actinides, (Np, Am and Cm) and hydrogen production, are also briefly covered. 相似文献
36.
37.
38.
We aim to understand the role of momentum-dependent interactions in transverse flow as well as in its disappearance. For the
present study, central collisions involving masses between 24 and 394 are considered. We find that the momentum-dependent
interactions have different impact in lighter colliding nuclei compared to heavier colliding nuclei. In lighter nuclei, the
contribution of the mean field towards flow is smaller compared to heavier nuclei where binary nucleon-nucleon collisions
dominate the scene. The inclusion of momentum-dependent interactions also explains the energy of the vanishing flow in the
12C + 12C reaction which otherwise was not possible with the static hard equation of state. An excellent agreement of our theoretical
attempt is found for balance energy with experimental data throughout the periodic table. 相似文献
39.
Study of magnetoresistance and conductance of bicrystal grain boundary in La0.67Ba0.33MnO3 thin film
La0.67Ba0.33MnO3 (LBMO) thin film is deposited on a 36.7°C SrTiO3 bicrystal substrate using laser ablation technique. A microbridge is created across bicrystal grain boundary and its characteristics
are compared with a microbridge on the LBMO film having no grain boundary. Presence of grain boundary exhibits substantial
magnetoresistance ratio (MRR) in the low field and low temperature region. Bicrystal grain boundary contribution in MRR disappears
at temperature T>175 K. At low temperature, I-V characteristic of the microbridge across bicrystal grain boundary is nonlinear. Analysis of temperature dependence of dynamic
conductance-voltage characteristics of the bicrystal grain boundary indicates that at low temperatures (T<175 K) carrier transport across the grain boundary in LBMO film is dominated by inelastic tunneling via pairs of manganese
atoms and tunneling through disordered oxides. At higher temperatures (T>175 K), magnetic scattering process is dominating. Decrease of bicrystal grain boundary contribution in magnetoresistance
with the increase in temperature is due to enhanced spin-flip scattering process. 相似文献
40.
We study a multi-period oligopolistic market for a single perishable product with fixed inventory. Our goal is to address
the competitive aspect of the problem together with demand uncertainty using ideas from robust optimization and variational
inequalities. The demand function for each seller has some associated uncertainty and we assume that the sellers would like
to adopt a policy that is robust to adverse uncertain circumstances. We believe this is the first paper that uses robust optimization
for dynamic pricing under competition. In particular, starting with a given fixed inventory, each seller competes over a multi-period
time horizon in the market by setting prices and protection levels for each period at the beginning of the time horizon. Any
unsold inventory at the end of the horizon is worthless. The sellers do not have the option of periodically reviewing and
replenishing their inventory. We study non-cooperative Nash equilibrium policies for sellers under such a model. This kind
of a setup can be used to model pricing of air fares, hotel reservations, bandwidth in communication networks, etc. In this
paper we demonstrate our results through some numerical examples. 相似文献