全文获取类型
收费全文 | 534篇 |
免费 | 10篇 |
国内免费 | 9篇 |
专业分类
化学 | 244篇 |
晶体学 | 1篇 |
力学 | 30篇 |
数学 | 102篇 |
物理学 | 176篇 |
出版年
2022年 | 4篇 |
2021年 | 9篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 11篇 |
2017年 | 12篇 |
2016年 | 16篇 |
2015年 | 10篇 |
2014年 | 13篇 |
2013年 | 28篇 |
2012年 | 22篇 |
2011年 | 30篇 |
2010年 | 10篇 |
2009年 | 16篇 |
2008年 | 30篇 |
2007年 | 15篇 |
2006年 | 24篇 |
2005年 | 28篇 |
2004年 | 24篇 |
2003年 | 19篇 |
2002年 | 18篇 |
2001年 | 21篇 |
2000年 | 13篇 |
1999年 | 6篇 |
1998年 | 11篇 |
1997年 | 8篇 |
1996年 | 6篇 |
1995年 | 11篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 8篇 |
1991年 | 10篇 |
1990年 | 6篇 |
1988年 | 5篇 |
1985年 | 6篇 |
1984年 | 9篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1975年 | 6篇 |
1974年 | 9篇 |
1973年 | 4篇 |
1971年 | 4篇 |
1970年 | 2篇 |
1968年 | 2篇 |
1967年 | 2篇 |
排序方式: 共有553条查询结果,搜索用时 250 毫秒
491.
A. M. Pak O. I. Kartonozhkina A. P. Pogorelskii E. M. Tsai D. V. Sokolskii 《Reaction Kinetics and Catalysis Letters》1981,16(2-3):265-270
Hydrogenation of dehydrolinalool and dehydrolinalyl acetate on 0.5% Pd/Al2O3 in C2–C5 alcohols of various structure has been studied at atmospheric and higher pressures of hydrogen. It is shown that the differences in selectivity of hydrogenation of dehydrolinalool to linalool and of dehydrolinalyl acetate to linalyl acetate is due to peculiarities in their structure.
0,5% Pd/Al2O3 C2–C5 . , .相似文献
492.
Erin?Bowley Erin?Mulvihill Jeffrey?C?Howard Brian?J?Pak Bing?Siang?GanEmail author 《BMC biochemistry》2005,6(1):29
Background
As a component of the progression from genomic to proteomic analysis, there is a need for accurate assessment of protein post-translational modifications such as phosphorylation. Traditional kinase assays rely heavily on the incorporation of γ-P32 radiolabeled isotopes, monoclonal anti-phospho-protein antibodies, or gel shift analysis of substrate proteins. In addition to the expensive and time consuming nature of these methods, the use of radio-ligands imposes restrictions based on the half-life of the radionucleotides and pose potential health risks to researchers. With the shortcomings of traditional assays in mind, the aim of this study was to develop a high throughput, non-radioactive kinase assay for screening Glycogen Synthase Kinase-3beta (GSK-3β) activity. 相似文献493.
In this work we have studied the effect of corrugation on the thermal diffusion (soret effect) in isotopic and non-isotopic fluid mixtures confined in a slit pore. We used a boundary driven non-equilibrium molecular dynamics to simulate thermal diffusion in Lennard–Jones (LJ) binary mixtures confined in structureless Steele 10-4-3 and atomistic Lennard–Jones pore walls. The results showed that for the isotopic mixture thermal diffusion factor for both wall types agrees and the corrugation of the LJ wall has no effect in isotopic mixture. However, for non-isotopic mixture confined in atomistic LJ pore the component with stronger attraction adsorbs more to the wall than the structureless Steele wall. The effect of corrugation of pore wall on the thermal diffusion is noticeable in narrow slit pore and mixture with large difference in molecular attraction parameter of components. 相似文献
494.
Gonzales JM Pak C Cox RS Allen WD Schaefer III HF Császár AG Tarczay G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(10):2173-2192
The energetics of the stationary points of the gas-phase reactions CH(3)X+F(-)-->CH(3)F+X(-) (X=F, Cl, CN, OH, SH, NH(2) and PH(2)) have been definitively computed using focal point analyses. These analyses entailed extrapolation to the one-particle limit for the Hartree-Fock and MP2 energies using basis sets of up to aug-cc-pV5Z quality, inclusion of higher-order electron correlation [CCSD and CCSD(T)] with basis sets of aug-cc-pVTZ quality, and addition of auxiliary terms for core correlation and scalar relativistic effects. The final net activation barriers for the forward reactions are: E (b/F,F)=-0.8, E (b/F, Cl)=-12.2, E (b/F,OH)=+13.6, E b/F,OH=+16.1, E b/F,SH=+2.8, Eb/F, NH=+32.8, and E b/F,PH =+19.7 kcal x mol(-1). For the reverse reactions E b/F,F= -0.8, Eb/Cl,F =+18.3, E b/CN,F=+12.2, E b/OH,F =-1.8, E b/SH,F =+13.2, E b/NH(2),=-1.5, and E b/PH(2) =+9.6 kcal x mol(-1). The change in energetics between the CCSD(T)/aug-cc-pVTZ reference prediction and the final extrapolated focal point value is generally 0.5-1.0 kcal mol(-1). The inclusion of a tight d function in the basis sets for second-row atoms, that is, utilizing the aug-cc-pV(X+d)Z series, appears to change the relative energies by only 0.2 kcal x mol(-1). Additionally, several decomposition schemes have been utilized to partition the ion-molecule complexation energies, namely the Morokuma-Kitaura (MK), reduced variational space (RVS), and symmetry adapted perturbation theory (SAPT) techniques. The reactant complexes fall into two groups, mostly electrostatic complexes (FCH(3).F(-) and ClCH(3).F(-)), and those with substantial covalent character (NCCH(3).F(-), CH(3)OH.F(-), CH(3)SH.F(-), CH(3)NH(2).F(-) and CH(3)PH(2).F(-)). All of the product complexes are of the form FCH(3).X(-) and are primarily electrostatic. 相似文献
495.
A method for constructing the Green's function for a differential equation with a deviating argument is proposed, and the boundary-value problemx'(t)+p (t) (t) x (h (t)) = f (t), t [a, b], x(a) = x(b) = 0 is used as an example. The method increases the possibilities for construction of Green's functions compared to the present methods, including the possibilities for representation of the Green's function in terms of the Cauchy function.Translated from Matematicheskie Zametki, Vol. 17, No. 3, pp. 443–448, March, 1975. 相似文献
496.
The highly functionalized bicyclic lactam 7 was prepared from diolefinic-2-piperidone 18 by the use of ruthenium-catalyzed RCM, and in turn, 18 was derived via a two-carbon addition process from readily accessible 4-olefinic-2-azetidinone 13. Bicyclic lactams 7 and 20 could serve as potentially valuable intermediates for the chiral synthesis of various hydroxylated indolizidine alkaloids as exemplified by the synthesis of (8S,8aS)-perhydro-8-indolizinol 19. 相似文献
497.
Handzy DO Bauer W Daffin FC Gaff SJ Gelbke CK Glasmacher T Gualtieri E Hannuschke S Huang MJ Kunde GJ Lacey R Li T Lisa MA Llope WJ Lynch WG Martin L Montoya CP Pak R Peaslee GF Pratt S Schwarz C Stone N Tsang MB Vander Molen AM Westfall GD Yee J Yennello SJ 《Physical review letters》1995,75(16):2916-2919
498.
T. M. Aliev N. K. Pak M. P. Rekalo 《Zeitschrift fur Physik C Particles and Fields》1995,66(4):663-679
We analyze the polarization properties of photons which are produced in the unpolarizedb-quark decay,bsg. Using the structure function formalism we carry out a general analysis of the polarization characteristics of in terms of the standard Stokes parameters. The expressions for five independent structure functions are constructed in terms of the weak magnetic transition form factors of the verticesbs andbsg. Numerical calculations of the Stokes parameters and various differential distributions forbsg are performed for the two-Higgs doublet model (2HDM). We studied the dependences of all these characteristics to the model parameters. These results were compared with the Standard Model predictions for different top quark masses. Strong sensitivity of the Stokes parameters, which defines the linear photon polarization, to the model is demonstrated. 相似文献
499.
500.
The specific features of the Ruderman-Kittel-Kasuya-Yosida interaction in an impurity graphene bilayer have been calculated
in the framework of the s-d model. Hydrogen atoms are considered as impurities. The calculations have demonstrated that the antiferromagnetic impurity-spin
ordering is preferable at short distances, while as the distance increases, the ordering becomes ferromagnetic. The dependences
of the exchange interaction constant on the problem parameters are shown. 相似文献