全文获取类型
收费全文 | 1559篇 |
免费 | 20篇 |
国内免费 | 6篇 |
专业分类
化学 | 889篇 |
晶体学 | 63篇 |
力学 | 32篇 |
数学 | 109篇 |
物理学 | 492篇 |
出版年
2022年 | 20篇 |
2021年 | 27篇 |
2020年 | 20篇 |
2019年 | 23篇 |
2018年 | 23篇 |
2017年 | 24篇 |
2016年 | 36篇 |
2015年 | 24篇 |
2014年 | 41篇 |
2013年 | 118篇 |
2012年 | 78篇 |
2011年 | 89篇 |
2010年 | 45篇 |
2009年 | 49篇 |
2008年 | 54篇 |
2007年 | 57篇 |
2006年 | 67篇 |
2005年 | 48篇 |
2004年 | 46篇 |
2003年 | 31篇 |
2002年 | 42篇 |
2001年 | 25篇 |
2000年 | 17篇 |
1999年 | 14篇 |
1998年 | 12篇 |
1997年 | 14篇 |
1996年 | 12篇 |
1995年 | 15篇 |
1994年 | 18篇 |
1993年 | 18篇 |
1992年 | 28篇 |
1991年 | 21篇 |
1990年 | 21篇 |
1989年 | 21篇 |
1988年 | 18篇 |
1987年 | 13篇 |
1986年 | 21篇 |
1985年 | 25篇 |
1984年 | 22篇 |
1983年 | 25篇 |
1982年 | 18篇 |
1981年 | 19篇 |
1980年 | 30篇 |
1979年 | 28篇 |
1978年 | 23篇 |
1977年 | 19篇 |
1976年 | 11篇 |
1975年 | 15篇 |
1973年 | 12篇 |
1971年 | 9篇 |
排序方式: 共有1585条查询结果,搜索用时 15 毫秒
121.
Valiente-Dobón JJ Steinhardt T Svensson CE Afanasjev AV Ragnarsson I Andreoiu C Austin RA Carpenter MP Dashdorj D de Angelis G Dönau F Eberth J Farnea E Freeman SJ Gadea A Garrett PE Görgen A Grinyer GF Hyland B Jenkins D Johnston-Theasby F Joshi P Jungclaus A Lieb KP Macchiavelli AO Moore EF Mukherjee G Napoli DR Phillips AA Plettner C Reviol W Sarantites D Schnare H Schumaker MA Schwengner R Seweryniak D Smith MB Stefanescu I Thelen O Wadsworth R 《Physical review letters》2005,95(23):232501
Three rotational bands in 74Kr were studied up to (in one case one transition short of) the maximum spin I(max) of their respective single-particle configurations. Their lifetimes have been determined using the Doppler-shift attenuation method. The deduced transition quadrupole moments reveal a modest decrease, but far from a complete loss of collectivity at the maximum spin I(max). This feature, together with the results of mean field calculations, indicates that the observed bands do not terminate at I = I(max). 相似文献
122.
Nagarajan K Joshi HK Chaudhury PK Pal K Cooney JJ Enemark JH Sarkar S 《Inorganic chemistry》2004,43(15):4532-4533
Synthesis of [PPh4]2[Mo(SPh)2(S2C2(CN)2)2] (2) from [PPh4]2[MoO(S2C2(CN)2)2] (1) has been achieved to mimic the postulated [Mo(S)6] core of polysulfide reductase with two thiolates and two bis(ene-dithiolate) ligands. Compound 2 reacts with polysulfide to yield H2S, modeling the function of polysulfide reductase. The facile conversion of 2 back to 1 in moist solvent suggests that the interconversion of the [MoIV = O] and [MoIV - X] (X = O-Ser, S-Cys, Se-Cys) moieties might occur in the DMSO reductase class of enzymes under appropriate hydrophobic/hydrophilic conditions. 相似文献
123.
The spectrum of xenon excited in a low-inductance vacuum spark was photographed at high resolution in the region of 9.5-15.5 nm. The observed transitions were identified as belonging to ions from Xe8+ to Xe13+. In the region of importance for extreme-ultraviolet lithography around 13.4 nm, the strongest lines were identified as 4d8-4d7 5p transitions in Xe10+. The identifications were made by use of energy parameters extrapolated along the isoelectronic sequence. 相似文献
124.
125.
126.
We study the action of translation operators on wavelet subspaces. This action gives rise to an equivalence relation on the
set of all wavelets. We show by explicit construction that each of the associated equivalence classes is non-empty. 相似文献
127.
We study the nonlinear phase response of a microring resonator coupled to a bus waveguide and the use of this nonlinear phase
shift to store information in the microring resonator and enhance the switching characteristics of a Mach-Zehnder interferometer
(MZI). By introducing coupling between adjacent microring resonators, the switching characteristics of the MZI can be exponentially
enhanced as a function of the number of microring resonators, when compared to the linear enhancement for uncoupled resonators.
With only a few moderate-finesse microring resonators, the switching power can be reduced to attowatt level, allowing for
photonic switching devices that operate at single-photon level in ordinary optical waveguides.
相似文献
128.
Pankaj S. Joshi 《Pramana》2007,69(1):119-135
We consider here the genericity aspects of spacetime singularities that occur in cosmology and in gravitational collapse.
The singularity theorems (that predict the occurrence of singularities in general relativity) allow the singularities of gravitational
collapse to be either visible to external observers or covered by an event horizon of gravity. It is shown that the visible
singularities that develop as final states of spherical collapse are generic. Some consequences of this fact are discussed.
相似文献
129.
Nishant N. Patel K. B. Joshi 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(1):19-23
Using empirical pseudopotential method Γ-L crossover is found for
the Ga0.74Al0.26Sb. The conduction band minimum is observed to
switch at the (0.87, 0, 0) point for Ga0.51Al0.49Sb which shifts to
the X point for Ga0.21Al0.79Sb and remains at X leading finally to
indirect band gap in AlSb. Band structure calculations for a large number of
alloys are performed and bowing parameters bX and bL are proposed
for the EX and EL respectively. Our findings may serve as
directive to select the materials in a range of composition to examine the
bowing parameters and thereby effective mass experimentally for the
GaxAl1-xSb alloys. 相似文献
130.
A. Chaudhury R. Khatirkar N.N. Viswanathan V. Singal A. Ingle S. Joshi I. Samajdar 《Journal of magnetism and magnetic materials》2007
Commercial supply, from several steel manufacturers, of low-silicon non-grain-oriented electrical steel was monitored over a span of several years. A total of 51 samples were selected—selected from many hundreds on the basis of large differences in magnetic properties, but absence of significant variations in chemistry (other than differences in silicon percentage). The selected samples were analyzed for crystallographic texture and for grain size. 相似文献