全文获取类型
收费全文 | 93篇 |
免费 | 1篇 |
国内免费 | 2篇 |
专业分类
化学 | 44篇 |
晶体学 | 1篇 |
力学 | 5篇 |
数学 | 15篇 |
物理学 | 31篇 |
出版年
2018年 | 2篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2013年 | 4篇 |
2012年 | 2篇 |
2011年 | 1篇 |
2010年 | 4篇 |
2008年 | 1篇 |
2007年 | 11篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 3篇 |
2002年 | 6篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1987年 | 3篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 5篇 |
1973年 | 3篇 |
1972年 | 1篇 |
1969年 | 3篇 |
1937年 | 1篇 |
1936年 | 2篇 |
1931年 | 2篇 |
1930年 | 1篇 |
排序方式: 共有96条查询结果,搜索用时 93 毫秒
1.
Five of the six possible aqueous two-salt mixtures from among NaCl, KCl, NaH2PO4,and KH2PO4 have been studied by the isopiestic method at 25°C. The sixth mixture, NaCl–KCl, has been studied previously. The deviations from ideal mixing behavior are described by a series of coefficients which were found by regression analysis. The coefficients were used to calculate the excess Gibbs energies of mixing for equal ionic strength fractions of each salt and the trace activity coefficient of each salt at an ionic strength of 2 mode-kg–1. The cross-square mixing rule is obeyed within experimental uncertainty for the excess Gibbs energies of mixing. 相似文献
2.
Iodomethyl-, chloromethyl-, and fluoromethyldimethylsulfonium salts, 4b-d, have been synthesized and are observed to be highly reactive molecules that exhibit extraordinary diversity with respect to the nature of their reactivity, undergoing facile direct substitution (S(N)2) reactions, but also being highly susceptible to electron-transfer reactions. Cyclic voltametry experiments indicated that the iodomethyldimethylsulfonium compound, 4b, is a potent electron acceptor, even surpassing the reactivity of perfluoro-n-alkyl iodides in that capacity. The iodo- and chloromethyldimethylsulfonium salts, 4b,c, as well as the analogous iodomethyltrimethylammonium salt, 3a, are shown to be reactive SET acceptors. 相似文献
3.
4.
Lindsay N. Childs 《代数通讯》2013,41(4):809-825
5.
Ronald F. Childs Brian D. Dickie Romolo Faggiani Colin A. Fyfe Colin J. L. Lock Roderick E. Wasylishen 《Journal of chemical crystallography》1985,15(1):73-87
The X-ray crystal structures ofE-N, N-dimethyl-3-phenyl-2-propenylideniminium perchlorate,1, andE-N, N-dimethyl-3-(p-methoxyphenyl)-2-propenylideniminium perchlorate,2, have been determined.E-N,N-dimethyl-3-phenyl-2-propenylideniminium perchlorate, (C11H14N+)(ClO4
–),1, is orthorhombic:Pmcn (No. 62)a=6.595(1),b=18,288(4),c=10.216(2) Å,Z=4.E-N, N-dimethyl-3-(p-methoxyphenyl)-2-propenylideniminium perchlorate, (C12H16NO+)(ClO4
–),2, is triclinic:P1 (No. 2) with cell dimensionsa=6.862(1),b=9.830(2),c=13.376(3) Å,=119.05(1),=114.99(2), =90.79(2)°, andZ=2. Data for both crystals were collected with the use of MoK radiation and a Syntex P21 diffractometer. The crystal structures were solved by standard methods and refined toR
1=0.0688,R
2=0.0772 for1 andR
1=0.0790 andR
2=0.0757 for 2 based on 869 and 1765 independent reflections, respectively. The bond distances are consistent with a highly localized structure with the positive charge situated principally in the iminium moiety. The13C NMR spectra of these salts were obtained on the crystalline solids by CPMAS methods. Since the13C chemical shifts of the salts were very similar, in both solution and solid states, it was concluded that the structures of the salts were comparable in both phases and were analogous. 相似文献
6.
The low temperature fluorescence spectra (4.2 K) of solid solutions of p-difluorobenzene-h4 (pDFB-h4) and -d4 have been recorded and analyzed. The absence of fluorescence from vibrationally excited states at 4.2 K eliminates the sequence and “hot band” structure which complicate the analysis of the vapor fluorescence spectrum. On the basis of a comparison of our vibrational analysis with those published for the vapor phase fluorescence, several incorrect assignments in the latter have been identified. The high resolution and lack of spectral congestion obtained in the low temperature matrix isolated fluorescence spectra also allowed additional vibrational assignments to be made. These results are of added importance because of the extensive use which has been made of pDFB for radiationless relaxation studies in the vapor phase. The phosphorescence spectrum of crystalline pDFB-h4 was observed with sufficient intensity to locate the electronic origin to make several vibrational assignments. Additionally, the zero-field splitting of the first triplet excited state was measured by optically detected magnetic resonance techniques. 相似文献
7.
This review deals with applications of digital computers to the evaluation of ionization constants of acids and bases, stability constants of metal complexes, concentrations of equilibrium mixtures, and the solution of rate equations. The use of computers permits systems of greatly increased complexity to be studied, and introduces additional methods of calculation such as numerical integration and Monte Carlo techniques. 相似文献
8.
S. Büttgenbach M. Herschel G. Meisel E. Schrödl W. Witte Prof. Dr. W. J. Childs 《Zeitschrift für Physik A Hadrons and Nuclei》1973,263(4):341-346
The5d 76s2 4F9/2 atomic ground state of191Ir and193Ir has been studied using the atomic-beam magnetic-resonance method. The results are:193Ir:g J(4F9/2)=1.29694 (3)191Ir:Δv(4F9/2; F=6?F=5)=659.26496 (12) MHzΔv( 4F9/2; F=5?F=4)=189.44002 (09) MHzΔv( 4F9/2; F=3?F=4)=84.05040 (80) MHzA=57.52148 (04) MHzB=471.20425 (57) MHzC=?0.020 (30) kHz193Ir:Δv( 4F9/2; F=6?F=5)=660.09043 (12) MHzΔv( 4F9/2; F=5?F=4)=224.47848 (13) MHzΔv( 4F9/2; F=?F=4)=33.53453 (89) MHzA=62.65556 (05) MHzB=426.23546 (64) MHzC=0.020 (30) kHz Using the magnetic dipole moments known by NMR-technique [1] we obtained for the electric quadrupole moments as calculated from the hyperfine interaction constantsA andB:Q(191Ir)=0.78 (20) barns,Q(193Ir)=0.70 (18) barns (uncorrected for core polarization effects). A calculation of the hyperfine anomaly yields:191 Δ 193=?0.00023 (10). The ratio of theB factors which should be the same as for the quadrupole moments turned out to be:B(191Ir)/B(193Ir)=Q(191Ir)/Q(193Ir)=1.105502(3). 相似文献
9.
10.
Lindsay N. Childs Gerald Garfinkel Morris Orzech 《Journal of Pure and Applied Algebra》1975,6(2):111-123
Let B(R) be the Brauer group of the integrally closed noetherian domain R with quotient field K. We reexamine the proof that B(R) → R(K) is monic for R regular from the point of view of factoriality of R and its extensions. For R local with maximal ideal m, henselization Rh and divisor class group Cl(R) we embed ker into . This is applied to obtain examples of non-regular geometric local domains R for which B(R) → B(K) is monic. 相似文献