全文获取类型
收费全文 | 185篇 |
免费 | 2篇 |
国内免费 | 2篇 |
专业分类
化学 | 111篇 |
晶体学 | 2篇 |
力学 | 1篇 |
数学 | 36篇 |
物理学 | 39篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 8篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 3篇 |
2014年 | 6篇 |
2013年 | 14篇 |
2012年 | 8篇 |
2011年 | 20篇 |
2010年 | 10篇 |
2009年 | 13篇 |
2008年 | 9篇 |
2007年 | 7篇 |
2006年 | 12篇 |
2005年 | 8篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1982年 | 1篇 |
1975年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有189条查询结果,搜索用时 31 毫秒
51.
Epsilon terms indexed by contexts were used by K. von Heusinger to represent definite and indefinite noun phrases as well as some other constructs of natural language. We provide a language and a complete first order system allowing to formalize basic aspects of this representation. The main axiom says that for any finite collection S
1,,S
k
of distinct definable sets and elements a
1,,a
k
of these sets there exists a choice function assigning a
i
to S
i
for all ik. We prove soundness and completeness theorems for this system S
i
fin
.
Mathematics Subject Classification (2000): 03B10, 03B65 相似文献
52.
The photolysis of 10,10-difluorophenanthren-9(10H)-one 1 in different solvents shows that the major competing reaction of the diradical formed by α-cleavage: recombination and hydrogen atom abstraction depends on the hydrogen atom donating ability of the solvent. Photolysis of 1 in cyclohexane in the presence of air or oxygen leads mainly to α-cleavage while photoreduction with the formation of 10-fluoro-9-phenanthrol occurs when the solution is deaerated prior to irradiation. In acetonitrile, a poor hydrogen donor, recombination of the diradical back to starting compound 1 is the sole process. 相似文献
53.
Darko Žubrinić 《Czechoslovak Mathematical Journal》2003,53(2):429-435
We consider a quasilinear elliptic problem whose left-hand side is a Leray-Lions operator of p-Laplacian type. If p < < N and the right-hand side is a Radon measure with singularity of order at x0A , then any supersolution in W1,p() has singularity of order at least (–p)/(p–1) at x0. In the proof we exploit a pointwise estimate of A-superharmonic solutions, due to Kilpeläinen and Malý, which involves Wolff's potential of Radon's measure. 相似文献
54.
55.
Zoran Samard?ijaRID=""ID="" To whom correspondence should be addressed Darko Makovec Miran ?eh 《Mikrochimica acta》2000,132(2-4):383-386
Yttrium-doped BaTiO3 ceramics have been studied as a potential material for positive temperature coefficient resistors (PTCR). The mechanism of
Y incorporation into BaTiO3 plays an important role for displaying good electrical properties. Determination of the amount of yttrium in the BaTiO3 as well as microstructure characterization of the samples were performed using SEM, EDS and WDS analysis. An optimized trace
element WDS quantitative analysis was applied to determine elemental concentrations for Ba, Ti and Y in the samples as accurately
as possible. BaTiO3 and Y2O3 were used as standards. Analysis was undertaken using a JEOL JXA 840A electron probe microanalyzer. WDS X-ray intensity measurements
were performed under 20 kV, 50 nA beam current and 0.2% preset standard counting deviation (σc) using a PET crystal. Measured k-ratios were quantified by ZAF matrix correction. Average results of WDS quantitative analysis showed 20.17 ± 0.08 at % Ti,
19.95 ± 0.09 at % Ba, 0.22 ± 0.03 at % Y, and 59.66 at % O. The results suggest incorporation of yttrium in the BaTiO3 preferentially at the Ba-sites, however partial incorporation of Y at Ti-sites could not be excluded. 相似文献
56.
Manda ?uri? Darko Babi? Ljiljana Paša-Toli? Janez Plavec 《Journal of organometallic chemistry》2003,687(1):85-99
Three new Pd(II) complexes, i.e. [PdCl2L]2 (A), PdCl2L2 (B) and [Pd(μ-Cl)(L-H)]2 (C), each with two diethyl [α-(4-benzenazoanilino)-2-hydroxybenzyl]phosphonates (L) bound to either one or two palladium atoms, are synthesized and characterized by elemental analysis, by IR, UV-vis and solid-state 13C-NMR spectra. Complexes B and C are additionally characterized by 1H-, 13C- and 31P-NMR and electrospray mass spectrometry (ESMS) studies using dimethylformamide (DMF) as a solvent. In DMF solution adducts A and B undergo spontaneous rearrangement into the cyclopalladated complex C. Dynamic 1H-NMR study of this rearrangement as well as of the reactions of L with PdCl2 and Na2PdCl4 revealed a complex equilibrium in DMF solutions and enabled the formation mechanism of all involved species to be resolved. The complex A is immediately solvolyzed producing two molecules of intermediate M [PdCl2(L)(DMF)]. Complex M was also the first intermediate in the reaction of L with PdCl2. Once present in concentration above 10−5 mol dm−3M dimerizes very fast into chloro-bridged dimer [PdCl(μ-Cl)(L)]2 (D) which undergoes cyclopalladation and converts into the complex C. The formation of C from the intermediate D is clearly demonstrated by the concentration dependence of the cyclopalladation reaction which has order greater than one. Chloride ions, released by cyclopalladation, react with D by splitting chloro-bridge and binding to metal atoms to produce byproduct [PdCl3(L)]− (T). The same species T are formed in the reaction of L with Na2PdCl4 whereby a chloride ion is replaced by the ligand L. The complex B undergoes similar, but slower, solvolytic reaction producing M and L while further reaction steps are identical as in the solvolysis of A. 相似文献
57.
58.
59.
Mervan Paši? Darko ?ubrini? Vesna ?upanovi? 《Bulletin des Sciences Mathématiques》2009,133(8):859-874
In order to measure fractal oscillatority of solutions at t=∞, we define oscillatory and phase dimensions of solutions of a class of second-order nonlinear differential equations. The relation between these two dimensions is found using formulas for box dimension of chirps and nonrectifiable spirals. Applications include the Liénard equation and weakly damped oscillators. 相似文献
60.