全文获取类型
收费全文 | 237篇 |
免费 | 6篇 |
专业分类
化学 | 130篇 |
晶体学 | 6篇 |
力学 | 12篇 |
数学 | 14篇 |
物理学 | 81篇 |
出版年
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 4篇 |
2014年 | 5篇 |
2013年 | 4篇 |
2012年 | 11篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 6篇 |
2007年 | 15篇 |
2006年 | 8篇 |
2005年 | 3篇 |
2004年 | 5篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1989年 | 2篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 11篇 |
1980年 | 6篇 |
1979年 | 10篇 |
1978年 | 7篇 |
1977年 | 9篇 |
1976年 | 7篇 |
1975年 | 9篇 |
1974年 | 7篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1970年 | 3篇 |
1935年 | 2篇 |
1934年 | 1篇 |
1909年 | 1篇 |
排序方式: 共有243条查询结果,搜索用时 31 毫秒
101.
E. Biémont P.-D. Dumont H.P. Garnir P. Palmeri P. Quinet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(2):199-204
Theoretical transition probabilities have been obtained for 54 n = 3 transitions depopulating the 3s3p
1Po, 3p2
3P, 1D, 1S, 3s3d
1D, 3D and 3p3d
3Po, 3Do, 3Fo, 1Fo, 1Do, 1Po levels, including 14 transitions not yet observed. Some of these predictions have been compared with experimental lifetimes
obtained by beam-foil spectroscopy for four n = 3 levels of K7+. An excellent agreement is observed between theory and experiment for all the levels.
Received 23 January 2002 / Received in final form 23 April 2002 Published online 19 July 2002 相似文献
102.
P.D. Dumont E. Biemont N. Grevesse 《Journal of Quantitative Spectroscopy & Radiative Transfer》1974,14(11):1127-1141
New beam-foil lifetime measurements of excited levels have been made for N I-N IV using lines in the vacuum ultraviolet spectral range. These values are compared with other experimental results and theoretical data. ‘Best’ values of absolute transition probabilities are proposed. 相似文献
103.
F. Bely-Dubau C. Camhy-Val A.M. Dumont 《Journal of Quantitative Spectroscopy & Radiative Transfer》1975,15(5):375-377
The experimental lifetimes given in Part I(1) are compared with theoretical lifetimes. Two sets of theoretical calculations obtained in intermediate coupling are considered. 相似文献
104.
Transsilylation Reaction with Di-tert-butyl(trimethylsilyl)phosphine Di-tert-butyl(trimethylsilyl)phosphine reacts with Dichlordimethylsilane, Trichlor(methyl)silane and silicon tetrachloride with elimination of Chlortrimethylsilane and formation of the new Silylphosphines [( CH3)3C]2PSi(CH3)3?nCln (n = 1, 2, 3). Only the compounds with n = 2 and 3 can be isolated in a pure state. The ir, raman, 1H-n.m.r. and 31P-n.m.r. spectroscopic data of the new compounds are discussed. 相似文献
105.
The metabolism of selenium (Se) in the human body has yet not completely been unravelled and hence, an efficient method for characterization and on-line monitoring of the main Se-compound in human urine after consumption of Se-rich food was developed. Total Se-concentration in human urine after consumption of several Se-rich products was measured with inductively coupled plasma mass spectrometry (ICP-MS). The highest Se concentration in urine was observed after 4-10 h. The urine samples were brought onto a reversed phase column and the Se was detected by ICP-MS. Parameters for liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS) measurements were optimized by using commercially available sugars, because it is known that some of the urinary metabolites contain a sugar moiety. In order to characterize the predominant Se-metabolite, it was necessary to extensively clean-up the sample and preconcentrate the species. The main metabolite was measured on its precursor ion on three different m/z according to three isotopes of Se. Relative peak surfaces matched the relative abundances of the isotopes. The product ions could be measured in a human urine sample in accordance to the product ions of the commercially available sugars. Moreover, the evidence of a selenosugar was demonstrated by the use of the Se-isotopes when measuring the product ions. LC-ESI-MS-MS was proven to be very efficient for the characterization of the main urinary Se-metabolite and can be used for on-line monitoring of the compound in urine samples. The method can be extended for clinical screening after consumption of Se-(en)rich(ed) food by use of the Se-isotopic profile and/or of the typical product ions of (methyl)-N-acetyl-hexosamines. 相似文献
106.
Slab-gel electrophoresis has been applied to the speciation of vanadium in serum. The electrophoresis separation is an adaptation of the blue native polyacrylamide gel electrophoresis separation necessary to ensure the stability of the vanadium-protein complex; Coomassie blue was used to shift the charges of the proteins and to stabilize the vanadium complex. The detection of the vanadium species was made possible by the use of the (48)V radiotracer and the phosphor-screen technology. The method was first developed using transferrin, incubated with (48)V, as a model. After it was proved that the vanadium-transferrin complex was stable during separation, the method was validated by separating serum incubated with (48)V. The efficiency of the separation was assessed according to two parameters: resolution and conservation of the species. First, the resolution of the separation was as expected from a native separation. Second, the release of free vanadium from the transferrin complex, which was the main vanadium species expected, was negligible, which proves that the species remain intact during separation. In accordance with the literature, it was found that vanadium binds to transferrin in incubated serum at these low concentrations. 相似文献
107.
Dimethylphenylsilyllithium adds to Z-γ-alkoxy-α,β-unsaturated esters to produce almost exclusively (i) the anti-adducts when the reaction is carried out in THF and (ii) the anti-adduct when carried out in the presence of HMPA. Poor stereocontrol is achieved with stereoisomeric E-γ-alkoxy-α,β-unsaturated esters. 相似文献
108.
Mlissa Dumartin Jean Septavaux Marion Donnier-Marchal Emeric Jeamet Elise Dumont Florent Perret Laurent Vial Julien Leclaire 《Chemical science》2020,11(31):8151
During the last two decades, disulfide-based dynamic combinatorial chemistry has been extensively used in the field of molecular recognition to deliver artificial receptors for molecules of biological interest. Commonly, the nature of library members and their relative amounts are provided from HPLC-MS analysis of the libraries, allowing the identification of potential binders for a target (bio)molecule. By re-investigating dynamic combinatorial libraries generated from a simple 2,5-dicarboxy-1,4-dithiophenol building block in water, we herein demonstrated that multiple analytical tools were actually necessary in order to comprehensively describe the libraries in terms of size, stereochemistry, affinity, selectivity, and finally to get a true grasp on the different phenomena at work within dynamic combinatorial systems.We show that multiple analytical tools are necessary in order to describe the different phenomena within disulfide-based dynamic combinatorial libraries in terms of size, stereochemistry, affinity and selectivity. 相似文献
109.
E. V. Vlasov V. V. Babinstev V. A. Bumazhnov S. Chekulaev G. N. Khromova A. I. Kotova A. M. Moiseev M. N. Ukhanov L. I. Saricheva L. N. Smirnova E. G. Boos B. O. Jautykov M. A. Jabiol C. Louédec J. Prevost J. Hanton J. Kesteman C. Poiret M. Barth J. J. Dumont M. Van Immerseel France-USSR Collaboration CERN-USSR Collaboration 《Zeitschrift fur Physik C Particles and Fields》1982,13(2):95-111
Results are presented on the inclusive production of π± mesons and protons in \(\bar p\) p interactions at an incident antiproton momentum of 32 GeV/c in the MIRABELLE bubble chamber, based on a sample of 55,000 inelastic events. The spectra of π+(π?) andp( \(\bar p\) ) are separated in the whole kinematically admitted region of phase space by a statistical method. The semi-inclusive and inclusive cross sections and the main average characteristics of π andp production are calculated. The invariant differential cross sections are studied as functions of the Fevnman scaling variablex, the rapidity and the transverse momentum. Thex distribution of π± mesons in the proton fragmentation region does not show any significant contribution from quark exchange or annihilation processes. A possible contribution of hard quark scattering on mesons or baryons is observed for large transverse momenta. 相似文献
110.
E. A. De Wolf J. J. Dumont F. Verbeure I. V. Ajinenko P. V. Chliapnikov V. P. Falaleev L. N. Gerdyukov A. E. Kurnosenko V. N. Riadovikov V. F. Tchumikin V. A. Uvarov A. P. Vorobjev F. Grard CERN-Soviet Union Collaboration 《Zeitschrift fur Physik C Particles and Fields》1982,12(2):105-112
Results are presented on inclusive production of resonant and non-resonant particle systems produced inK + p interactions at 32 GeV/c. We compareK *+(892), \(\bar \Sigma ^{ * - } \) (1385), Σ*±(1385), and ?0 inclusivex-spectra with the ones of non-resonantK s 0 π±, \(\bar \Lambda \pi ^ - \) , Λπ± and π+π? pairs at the same effective mass. Resonance-particle pairsK *+π±, Σ*+π?, and \(\bar \Sigma ^{ * - } \pi ^ - \) are also studied together with non-resonant tripletsK s 0 π±, Λπ+π?, \(\bar \Lambda \pi ^ - \pi ^ - \) . The invariantx-spectra of resonant particle pairs decrease less rapidly withx then the corresponding non-resonant pairs. Comparison with quark-recombination predictions indicates that the particles, resonances and multiparticle systems are probably created off a single valence quark or diquark instead of carrying all possible valence-quarks. 相似文献