全文获取类型
收费全文 | 401篇 |
免费 | 13篇 |
国内免费 | 3篇 |
专业分类
化学 | 302篇 |
晶体学 | 2篇 |
力学 | 9篇 |
数学 | 66篇 |
物理学 | 38篇 |
出版年
2023年 | 2篇 |
2022年 | 14篇 |
2021年 | 12篇 |
2020年 | 8篇 |
2019年 | 7篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 9篇 |
2015年 | 9篇 |
2014年 | 5篇 |
2013年 | 18篇 |
2012年 | 28篇 |
2011年 | 24篇 |
2010年 | 12篇 |
2009年 | 5篇 |
2008年 | 23篇 |
2007年 | 19篇 |
2006年 | 29篇 |
2005年 | 29篇 |
2004年 | 22篇 |
2003年 | 14篇 |
2002年 | 14篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 9篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1989年 | 3篇 |
1986年 | 2篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1980年 | 3篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1973年 | 4篇 |
1971年 | 2篇 |
1959年 | 1篇 |
1877年 | 2篇 |
1870年 | 2篇 |
1869年 | 1篇 |
1867年 | 3篇 |
1865年 | 1篇 |
1863年 | 2篇 |
排序方式: 共有417条查询结果,搜索用时 0 毫秒
41.
This paper overviews the work made by our group during the past 10–15 years on crystalline systems, semiconductor surfaces,
molecular complexes and on materials of interest for technological applications, such as the defective silicon or the novel
generation thermoelectric materials. Our main aim of extracting chemical insight into the analysis of electron densities and
computed wave functions is illustrated through a number of examples. The recently proposed Source Function analysis is reviewed
and a few of its more interesting applications are summarized. Software package developments, motivated by the need of a direct
comparison with experiment or by the help these packages can provide for interpreting complex experimental outcomes, are described
and future directions outlined. A particular emphasis is given to the TOPOND and TOPXD programs, which enable one to analyze
theoretical and experimental crystalline densities using the rigorous framework of the Quantum Theory of Atoms in Molecules,
due to Bader. 相似文献
42.
Emmanuelle Augeraud-Veron Mauro Bambi Fausto Gozzi 《Journal of Optimization Theory and Applications》2017,173(2):584-611
In this paper, we study an economic model, where internal habits play a role. Their formation is described by a more general functional form than is usually assumed in the literature, because a finite memory effect is allowed. Indeed, the problem becomes the optimal control of a standard ordinary differential equation, with the past of the control entering both the objective function and an inequality constraint. Therefore, the problem is intrinsically infinite dimensional. To solve this model, we apply the dynamic programming approach and we find an explicit solution for the associated Hamilton–Jacobi–Bellman equation, which lets us write the optimal strategies in feedback form. Therefore, we contribute to the existing literature in two ways. Firstly, we fully develop the dynamic programming approach to a type of problem not studied in previous contributions. Secondly, we use this result to unveil the global dynamics of an economy characterized by generic internal habits. 相似文献
43.
44.
Fausto Sestini 《Fresenius' Journal of Analytical Chemistry》1877,16(1):467-468
Ohne Zusammenfassung 相似文献
45.
Ohne ZusammenfassungVon den Verfassern mitgetheilt; aus dem Italienischen übersetzt von der Redaction. 相似文献
46.
47.
Kaczor A Gómez-Zavaglia A Cardoso AL Pinho e Melo TM Fausto R 《The journal of physical chemistry. A》2006,110(37):10742-10749
The aliphatic 2H-azirine, methyl 3-methyl-2H-azirine-2-carboxylate (MMAC), has been synthesized and its monomeric form investigated by IR spectroscopy in an argon matrix, at 10 K, as well as theoretically (DFT/B3LYP/6-311++G(d,p)). Two low-energy conformers of MMAC (Ct and Cc) were found in the matrix, both exhibiting the cis conformation around the C-O bond but differing in the arrangement around the C-C(alpha) bond. The two conformers were photoreactive upon in situ broadband UV excitation (lambda > 235 nm), yielding nitrile ylide (P1) and ketene imine (P2) type products, which resulted from cleavage of the C-C or C-N bond, respectively. The kinetics of the reactions leading to the formation of P1 and P2 are of first order, with the processes being favored when the reactant is in the Cc conformation. Very interestingly, the C-N bond photocleavage, which is unusual for aliphatic 2H-azirines, was found to be preferred over the generally favored in 2H-azirines C-C bond breakage. This behavior is attributed to the presence in the molecule of the electron-withdrawing methoxycarbonyl substituent, which accelerates the intersystem crossing toward the T(1) triplet state and, in this way, favors the C-N bond cleavage. In addition to the primary photoprocesses leading to formation of P1 and P2, secondary photoprocesses leading to the decarboxylation and decarbonylation of P2 have been also observed. 相似文献
48.
Piercarlo Mustarelli Corrado Tomasi Marco Villa Gian Battista Appetecchi Fausto Croce 《Ionics》1995,1(2):147-152
Two composite gel electrolytes prepared from mixtures of poly(acrylonitrile) (PAN), propylene carbonate (PC), ethylene carbonate
(EC) and LiClO4 have been studied with differential scanning calorimetry (DSC) and7Li-6Li NMR. The data allow estimation of ionic conductivities, local (short range) diffusivities, and lattice dynamics. Furthermore,
they point to an unexpected behavior of the Li-rich sample that hints to a complex LiClO4-PAN phase diagram.
Paper presented at the 1st Euroconference on Solid State Ionics, Zakynthos, Greece, September 11–18,1994 相似文献
49.
E. Arimondo F. Calderazzo F. Fuso C. Toffi 《Applied Physics A: Materials Science & Processing》1998,66(4):407-411
2 . The dependence of the ion production on the laser ablation parameters is investigated and the expansion dynamics of the
ablated species is studied through time and space resolved measurements of the ion yield. We discuss our observations on the
basis of reactions involving neutral and ionized carbon-based species.
Received: 11 March 1997/Accepted: 30 June 1997 相似文献
50.