全文获取类型
收费全文 | 3167篇 |
免费 | 104篇 |
国内免费 | 27篇 |
专业分类
化学 | 1974篇 |
晶体学 | 28篇 |
力学 | 85篇 |
数学 | 650篇 |
物理学 | 561篇 |
出版年
2023年 | 14篇 |
2022年 | 45篇 |
2021年 | 85篇 |
2020年 | 76篇 |
2019年 | 88篇 |
2018年 | 80篇 |
2017年 | 69篇 |
2016年 | 124篇 |
2015年 | 112篇 |
2014年 | 141篇 |
2013年 | 237篇 |
2012年 | 206篇 |
2011年 | 218篇 |
2010年 | 152篇 |
2009年 | 150篇 |
2008年 | 187篇 |
2007年 | 181篇 |
2006年 | 146篇 |
2005年 | 123篇 |
2004年 | 99篇 |
2003年 | 73篇 |
2002年 | 79篇 |
2001年 | 35篇 |
2000年 | 40篇 |
1999年 | 30篇 |
1998年 | 20篇 |
1997年 | 22篇 |
1996年 | 35篇 |
1995年 | 27篇 |
1994年 | 24篇 |
1993年 | 21篇 |
1992年 | 28篇 |
1991年 | 13篇 |
1990年 | 21篇 |
1989年 | 14篇 |
1988年 | 18篇 |
1987年 | 12篇 |
1986年 | 12篇 |
1985年 | 15篇 |
1984年 | 25篇 |
1983年 | 15篇 |
1982年 | 16篇 |
1981年 | 15篇 |
1980年 | 14篇 |
1979年 | 11篇 |
1978年 | 24篇 |
1977年 | 22篇 |
1976年 | 12篇 |
1970年 | 7篇 |
1968年 | 10篇 |
排序方式: 共有3298条查询结果,搜索用时 328 毫秒
211.
Małgorzata Borówko Krzystof Stępniak Stefan Sokołowski Roman Zagórski 《Czechoslovak Journal of Physics》1999,49(7):1067-1075
The structure of liquid-gas interface of associating Lennard-Jones particles is studied using the density-functional theory
and the Monte Carlo simulation. The model with one bonding site per particle is considered. It is shown that the considered
version of the density functional is quite successful in predicting the gas-liquid density profile. 相似文献
212.
The kinetic and activation parameters for the rotation about the CC double bond and the C-N single bond in the compounds listed in Table 1 were determined by variable temperature NMR spectroscopy. Complete line shape analyses, using a computer REEP program, were carried out on several systems. The main objective of the present study is to determine the effect of the ring size in II on the two types of kinetic processes. 相似文献
213.
214.
215.
Results of uniaxial tension and compression experiments are reported on crosslinked polydimethylsiloxane (PDMS) networks in the unswollen state over the range 0.5 < α?1 < 1.2 where α is the extension ratio. Curves representing the reduced force [f] = f(V0/V)1/3(α – α?2)?1 plotted against α?1 can be approximated by straight lines for 0.5 < α?1 < 0.9, in agreement with the phenomenological Mooney equation. As α?1 approaches 1, however, they tend to level off and continue into the α?1 > 1 region with decreasing slope. These results are in agreement with the predictions of recent elasticity theories that incorporate the effect of junction-chain entanglements in the elastic free energy. 相似文献
216.
A recent paper by Tewari and Yadav on the dielectric function at low electronic densities is discussed. 相似文献
217.
Tamar Burak 《Israel Journal of Mathematics》1972,12(1):79-93
Let A be the closed unbounded operator inL
p(G) that is associated with an elliptic boundary value problem for a bounded domainG. We prove the existence of a spectral projectionE determined by the set Γ = {λ;θ
1≦argλ≦θ
2} and show thatAE is the infinitesimal generator of an analytic semigroup provided that the following conditions hold: 1<p<∞; the boundary
ϖΓ of Γ is contained in the resolvent setp(A) ofA;π/2≦θ<θ
2≦3π/2 ; and there exists a constantc such that (I)││(λ-A)-1││≦c/│λ│ for λ∈ϖΓ. The following consequence is obtained: Suppose that there exist constantsM andc such that λ∈p(A) and estimate (I) holds provided that |λ|≧M and Re λ=0. Then there exist bounded projectionE
− andE
+ such thatA is completely reduced by the direct sum decompositionL
p(G)=E−Lp (G) ⊕E+Lp (G) and each of the operatorsAE
− and—AE
+ is the infinitestimal generator of an analytic semigroup. 相似文献
218.
S. Roman A.K. Basak J.B.A. England J.M. Nelson N.E. Sanderson F.D. Santos A.M. Eiró 《Nuclear Physics A》1977,289(2):269-274
The tensor analysing power of the 27Al(d, 3He)26Mg reaction has been measured at Ed = 12.4 MeV. The results are reproduced by predictions of the DWBA including D-state components in the 3He wave function. The magnitude of the tensor analysing power provides information on the asymptotic D-state to S-state ratio in the 3He wave function. The value obtained for 3He is in agreement with the corresponding value for 3H. 相似文献
219.
Statistical properties of resonance fluorescence of a three-level atom, interacting with a monochromatic, strong laser field are examined. Analytical formulas, describing first- and second-order correlation functions are presented. The effect of antibunching is predicted and the nontrivial difference between the statistical properties of differently polarized fluorescence is discussed. 相似文献
220.
Constituents of Osmanthus Absolute, Ist communication:2,5-Epoxy-megastigma-6,8-dienes Besides some further ionone derivatives we identified two new bicyclic oxacompounds ( 1a / 1b ) of the megastigmane type in the Osmanthus absolute. Isolation, special features of their spectral datas and synthesis starting from ethyl α-safranate are described. The synthetic pathway choosen allowed the additional identification of four substances occurring in the same natural substrate, because some synthetic by-products formed int he reaction sequence exhibited corresponding spectra and GLC. retention as the hitherto unknown components of the Osmanthus absolute. 相似文献