全文获取类型
收费全文 | 120篇 |
免费 | 0篇 |
专业分类
化学 | 34篇 |
力学 | 16篇 |
数学 | 26篇 |
物理学 | 44篇 |
出版年
2019年 | 2篇 |
2018年 | 2篇 |
2016年 | 5篇 |
2014年 | 2篇 |
2013年 | 3篇 |
2012年 | 3篇 |
2011年 | 4篇 |
2010年 | 2篇 |
2009年 | 8篇 |
2008年 | 2篇 |
2007年 | 6篇 |
2006年 | 6篇 |
2005年 | 4篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 3篇 |
2000年 | 7篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1982年 | 2篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1968年 | 1篇 |
1962年 | 2篇 |
1946年 | 1篇 |
1929年 | 1篇 |
1926年 | 1篇 |
1925年 | 1篇 |
1922年 | 1篇 |
1920年 | 1篇 |
1919年 | 1篇 |
1916年 | 1篇 |
1873年 | 1篇 |
1869年 | 1篇 |
1858年 | 1篇 |
排序方式: 共有120条查询结果,搜索用时 62 毫秒
41.
Massimo Curini Francesco Epifano MariaCarla Marcotullio Ornelio Rosati Yousheng Guan Ernest Wenkert 《Helvetica chimica acta》2000,83(4):755-759
The Kanematsu transformation was employed for the preparation of tetrahydroisobenzofuran‐4‐carboxylic acid ( 12 ), α‐methylation, subsequent conversion into the diazoethanone 14 , and, finally, treatment with dirhodium tetraacetate of which furnished the hydrindanone 1 of the steroid C‐D ring structure. 相似文献
42.
43.
O. Benhar C. Ciofi degli Atti S. Fantoni S. Rosati A. Kallio L. Lantto P. Toropainen 《Physics letters. [Part B]》1976,64(4):395-398
Employing two model central interactions the binding energy of nuclear matter is calculated within the framework of the Jastrow variational approach using different types of constrains and including all the contributions from hypernetted-chain diagrams. 相似文献
44.
Summary Approximate integral equations, derived by interpolating between HNC and PY approaches, have been used to calculate the pair
distribution function for quantum Bose and Fermi fluids. The equations contain a free parameter wich is determined in such
a way that a consistency condition is satisfied. The results obtained for liquid4He and3He improve upon the PY and HNC equations and are in good agreement with the Monte Carlo results.
Riassunto La funzione di distribuzione a due corpi per fluidi bosonici e fermionici è stata calcolata risolvendo delle equazioni integrali approssimate, ottenute da una conveniente interpolazione tra le tecniche HNC e PY. Le equazioni contengono un parametro libero che è fissato soddisfacendo una condizione di consistenza. I risultati ottenuti per4He e3He liquidi migliorano quelli di HNC e PY e risultano in buon accordo con i risultati ricavati con tecniche di Montecarlo.
Резюме Приближенные интегральные уравнения, выведенные с помощью интерполяции между HNC и PY подходами, используются для вычисления функции распределения пар для квантовых Бозе—и Ферми-жидкостей. Уравнения содержат свободный параметр, который определяется таким образом, что выполняется условие совместимости. Результаты, полученные для жидких4He и3He улучшают результаты вычислений на основе PY и HNC уравнений и согласуются с результатами по методу Монте-Карло.相似文献
45.
The authors have investigated CO band emissions arising from the dissociative recombination of HCO(+) and HOC(+) ions with thermal electrons in a flowing afterglow plasma. The quantitative analysis of the band intensities showed that HCO(+) recombination forms the long-lived CO(a (3)Pi) state with a yield of 0.23+/-0.12, while HOC(+) recombination favors formation of CO(a' (3)Sigma(+)) and CO(d (3)Delta) with a combined yield of greater than 0.4. The observed vibrational distribution for the CO(a) state reproduces theoretical predictions quite well. The vibrational distributions for CO(a') and CO(d) are, in part, inverted, presumably as a consequence of a change in CO equilibrium bond length during recombination. The observations are compatible with current knowledge of the potential surfaces of states of HCO and HCO(+). 相似文献
46.
The last decade of research on κ-Minkowski noncommutative spacetime has been strongly characterized by a controversy concerning the speed of propagation of massless particles. Most arguments suggested that this speed should depend on the momentum of the particle strongly enough to be of interest for some ongoing experimental studies. But the only explicit derivations of worldlines in κ-Minkowski predicted no momentum dependence for the speed of massless particles. We return to this controversy equipped with the recent understanding that in some quantum spacetimes coincidences of events assessed by an observer who is distant from the events can be artifactual. We therefore set up our investigation in such a way that we never rely on the assessment of coincidences of events by distant observers. This allows us to verify explicitly that in κ-Minkowski simultaneously-emitted massless particles of different momentum are detected at different times, and establish a linear dependence of the detection times on momentum. 相似文献
47.
Lilia Rosati 《Topology and its Applications》2012,159(5):1388-1403
Let M be a smooth manifold and let F be a codimension one, C∞ foliation on M, with isolated singularities of Morse type. The study and classification of pairs (M,F) is a challenging (and difficult) problem. In this setting, a classical result due to Reeb (1946) [11] states that a manifold admitting a foliation with exactly two center-type singularities is a sphere. In particular this is true if the foliation is given by a function. Along these lines a result due to Eells and Kuiper (1962) [4] classifies manifolds having a real-valued function admitting exactly three non-degenerate singular points. In the present paper, we prove a generalization of the above mentioned results. To do this, we first describe the possible arrangements of pairs of singularities and the corresponding codimension one invariant sets, and then we give an elimination procedure for suitable center-saddle and some saddle-saddle configurations (of consecutive indices).In the second part, we investigate if other classical results, such as Haefliger and Novikov (Compact Leaf) theorems, proved for regular foliations, still hold true in presence of singularities. At this purpose, in the singular set, Sing(F) of the foliation F, we consider weakly stable components, that we define as those components admitting a neighborhood where all leaves are compact. If Sing(F) admits only weakly stable components, given by smoothly embedded curves diffeomorphic to S1, we are able to extend Haefliger?s theorem. Finally, the existence of a closed curve, transverse to the foliation, leads us to state a Novikov-type result. 相似文献
48.
The implementation of the projected algorithm and of the consistent tangent tensor for general isotropic three-invariant elastoplastic models under plane stress conditions discussed in Part I of this paper [Valoroso, N., Rosati, L., 2008. Consistent derivation of the constitutive algorithm for plane stress isotropic plasticity. Part I: Theoretical formulation. International Journal of Solids and Structures, doi: 10.1016/j.ijsolstr.2008.08.012.] is addressed. The connections between the general three-dimensional case and the plane stress problem are analyzed in detail and an algorithmic treatment taking full advantage of the isotropic properties of the model is presented. In particular, intrinsic (matrix-free) expressions are provided for all steps of the stress computation scheme that allow one to carry out the numerical implementation in a way that is completely independent from the matrix representations. The numerical performances of the present solution scheme are evaluated through representative numerical examples. 相似文献
49.
50.
Mario Rosati 《Annali di Matematica Pura ed Applicata》1962,58(1):109-123
Sunto Si considera il modello V, di dimensione complessa 3r-2, della varietà degli elementi differenziali del secondo ordine di
uno spazio proiettivo complesso Sr, costruito daG. Gherardelli, E. Bompiani, C. Longo. In questo lavoro tale modello viene considerato come varietà topologica a 2(3r-2) dimensioni reali e, mediante l'uso di
un opportuno complesso cellulare, se ne determina il gruppo di omologia intera, assegnando altresì un semplice significato
geometrico, nello spazio Sr, per i sistemi fondamentali di cicli delle varie dimensioni. Ne consegue, in particolare, che il gruppo di omologia di V
è isomorfo a quello del prodotto di un Sr-1 per la varietà degli elementi di primo ordine di un Sr, in accordo con un risultato diF. Gherardelli ottenuto per altra via; ma si stabilisce d' altra parte che V non è, almeno in generale, omeomorfa a tale prodotto. Si prova,
per inciso, che anche la varietá degli elementi di primo ordine di Sr, non è prodotto di un Sr-1 per un Sr, quantunque le due varietà abbiano anch'esse gruppi di omologia isomorfi.
A Enrico Bompiani in occasione del suo Giubileo scientifico.
Lavoro eseguito nell'ambito del gruppo di ricerca n. 37 del C. N. R. per l'anno accademico 1960–61. 相似文献