全文获取类型
收费全文 | 60篇 |
免费 | 3篇 |
专业分类
化学 | 37篇 |
力学 | 5篇 |
数学 | 4篇 |
物理学 | 17篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 2篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 1篇 |
2013年 | 1篇 |
2011年 | 5篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 2篇 |
2007年 | 6篇 |
2006年 | 1篇 |
2002年 | 4篇 |
1999年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 3篇 |
排序方式: 共有63条查询结果,搜索用时 296 毫秒
1.
Cusinato Marco Guercilena Federico Maria Perego Albino Logoteta Domenico Radice David Bernuzzi Sebastiano Ansoldi Stefano 《The European Physical Journal A - Hadrons and Nuclei》2022,58(5):1-69
The European Physical Journal A - PUMA, antiProton Unstable Matter Annihilation, is a nuclear-physics experiment at CERN aiming at probing the surface properties of stable and rare isotopes by use... 相似文献
2.
Giannatiempo A. Nannini A. Perego A. Sona P. 《The European Physical Journal A - Hadrons and Nuclei》2002,13(3):339-347
The states of 104Pd, populated in the EC-β+ decay of the ground ( J π = 5+) and metastable ( J π = 2+) states of 104Ag, have been investigated in the framework of the proton-neutron interacting boson model, extending a previous analysis to take into account the newly appeared experimental data. All positive-parity states up to an excitation energy of 3 MeV and spin in the range J = 1-6, fed by more than 0.3% in the decay of the parent nucleus, have been considered. As a result, strong evidence has been found for interpreting most of these states as states of collective nature having a quite pure full- or mixed-symmetry character and, in particular, for identifying the 1+ level at 2276 keV as the lowest 1+ mixed-symmetry state. 相似文献
3.
4.
Fábio C. Sampaio Paolo Torre Flávia M. Lopes Passos Célia Alencar de Moraes Patrizia Perego Attilio Converti 《Applied biochemistry and biotechnology》2007,136(2):165-181
To obtain in-depth information on the overall metabolic behavior of the new good xylitol producer Debaryomyces hansenii UFV-170, batch bioconversions were carried out using semisynthetic media with compositions simulating those of typical acidic
hemicellulose hydrolysates of sugarcane bagasse. For this purpose, we used media containing glucose (4.3–6.5 g/L), xylose
(60.1–92.1 g/L), or arabinose (5.9–9.2 g/L), or binary or ternary mixtures of them in either the presence or absence of typical
inhibitors of acidic hydrolysates, such as furfural (1.0–5.0 g/L), hydroxymethylfurfural (0.01–0.30 g/L), acetic acid (0.5–3.0
g/L), and vanillin (0.5–3.0 g/L). D. hansenii exhibited a good tolerance to high sugar concentrations as well as to the presence of inhibiting compounds in the fermentation
media. It was able to produce xylitol only from xylose, arabitol from arabinose, and no glucitol from glucose. Arabinose metabolization
was incomplete, while ethanol was mainly produced from glucose and, to a lesser less extent, from xylose and arabinose. The
results suggest potential application of this strain in xyloseto-xylitol bioconversion from complex xylose media from lignocellulosic
materials. 相似文献
5.
The cross section for the reaction 4He(6, γ)10B at the resonance corresponding to the 5.166 MeV level of 10B is found to depend appreciably on the vector polarization of 6Li, due to the parity mixing in this level. The expected effect ranges from 2.3 × 10?4 to 3.8 × 10?3 according to the assumptions on weak-interaction models. 相似文献
6.
Improved extraction of vegetable oils under high-intensity ultrasound and/or microwaves 总被引:3,自引:0,他引:3
Cravotto G Boffa L Mantegna S Perego P Avogadro M Cintas P 《Ultrasonics sonochemistry》2008,15(5):898-902
Ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) techniques have been employed as complementary techniques to extract oils from vegetable sources, viz, soybean germ and a cultivated marine microalga rich in docosahexaenoic acid (DHA). Ultrasound (US) devices developed by ourselves, working at several frequencies (19, 25, 40 and 300 kHz), were used for US-based protocols, while a multimode microwave (MW) oven (operating with both open and closed vessels) was used for MAE. Combined treatments were also studied, such as simultaneous double sonication (at 19 and 25 kHz) and simultaneous US/MW irradiation, achieved by inserting a non-metallic horn in a MW oven. Extraction times and yields were compared with those resulting from conventional procedures. With soybean germ the best yield was obtained with a ‘cavitating tube’ prototype (19 kHz, 80 W), featuring a thin titanium cylinder instead of a conventional horn. Double sonication, carried out by inserting an immersion horn (25 kHz) in the same tube, improved the yield only slightly but halved the extraction time. Almost comparable yields were achieved by closed-vessel MAE and simultaneous US/MW irradiation. Compared with conventional methods, extraction times were reduced by up to 10-fold and yields increased by 50–500%. In the case of marine microalgae, UAE worked best, as the disruption by US of the tough algal cell wall considerably improved the extraction yield from 4.8% in soxhlet to 25.9%. Our results indicate that US and MW, either alone or combined, can greatly improve the extraction of bioactive substances, achieving higher efficiency and shorter reaction times at low or moderate costs, with minimal added toxicity. 相似文献
7.
The aim of this research was to study the recovery of phenolic compounds from grape seeds, by-products from winemaking industries, using ethanolic solid-liquid extraction. For such a purpose, the combined effects of the extraction time (9, 19 and 29?h) and the solid-liquid ratio (0.10, 0.20 and 0.30?gdw?mL(-1)), were investigated (where dw?=?dry waste). Results demonstrated that Pinot Noir seeds had high levels of both total polyphenols (73.66?mg(Gallic Acid Equivalent)?gdw(-1)) and flavonoids (30.90?mg(Catechin Equivalent)?gdw(-1)), being the optimum extraction time 19?h approximately. The main phenolic compounds analysed with high performance liquid chromatography were catechin and quercetin with a maximum extraction yield obtained at 29?h (362.23 and 339.35?mg/100?gdw, respectively). Concentration of the polyphenols and their antiradical powers are demonstrated to have a significant linear correlation. 相似文献
8.
G. Del Piero G. Perego S. Cucinella M. Cesari A. Mazzei 《Journal of organometallic chemistry》1977,136(1):13-18
The crystall and molecular structures of (ClAlN-i-Pr)6 (I), and of (Me0.83H0.17AlN-i-Pr)6(MeAlN-i-Pr)6 have been determined by single crystal three-dimensional X-ray analysis. Block-matrix least-squares refinements led to conventional R factor of 0.039 for I and 0.037 for II. The compounds are isostructural, as the cage molecules consist of a prismatic hexagonal framework, (AlN)6, similar to that observed for the parent hydrogenated analogue (HAlN-i-Pr)6.Some differences in bond distances and angles are discussed, in connection with the different Al-bonded substituents. Crystal data: I, trigonal space group R; a = 17.083(2), c = 9.652(1); Z = 3; Dc 1.46 g cm?3; II, trigonal space group R, a = 17.378(3), c = 9.706(3) »; Z = 3; Dc 1.15 g cm?3. 相似文献
9.
G. Perego G. Del Piero M. Cesari A. Zazzetta G. Dozzi 《Journal of organometallic chemistry》1975,87(1):53-60
The compound [(HAlN-i-Pr)2(H2AlNH-i-Pr)3] has been prepared and the crystal and molecular structure determined by an X-ray analysis, carried out with three-dimensional data collected on a diffractometer. The molecule is made up of a cyclohexane-type ring, [(HAlN-i-Pr)2(H2AlNH-i-Pr)], in skewboat conformation, on each side of which is bonded an -H2AlNH-i-Pr- bridging unit between a nitrogen atom and an aluminum atom of the ring. The molecule lies on a binary axis of the crystal, but this symmetry is fulfilled only by a statistical orientation of the asymmetric molecular units (the statistical model is not however completely defined). The AlN bond lengths range from 1.901 to 1.985 Å; the average NC bond length is 1.527(9) Å. Main crystal data are: monoclinic space group C2/c; a = 10.15(2), b = 21.64(3), c = 12.84(2) Å, β = 111.9(5)°; Z = 4; calculated density 1.095 g/cm3. The structure was solved by direct methods and block-matrix least-squares converged to an R value of 5.6%. 相似文献
10.
G. Perego M. Cesari G. Del Piero A. Balducci E. Cernia 《Journal of organometallic chemistry》1975,87(1):33-41
The crystal and molecular structure of the adduct (HAlN-i-Pr)6AlH3 has been determined from single-crystal and three dimensional X-ray diffraction data collected by counter methods. The cage-type molecular structure consists of two six-membered rings, (AlN)3, joined together by four adjacent transverse AlN bonds; the loss of two of these bonds allows the complexation of one alane molecule, with five-coordination of the aluminum (trigonal bipyramidal geometry), through two AlN bonds and two AlHAl bridge bonds. The AlN bond lengths range from 1.873 to 1.959 Å; the average AlH bond length is 1.50(1) Å for the four-coordinated aluminum atoms; the average distance of the two apical hydrogens from the five-coordinated aluminum atom is 1.92(5) Å. Colourless prismatic crystals of the compound have the following crystal data: triclinic space group P; a = 17.13(2); b = 10.78(2); c = 10.20(2) Å; α = 124.3(4), β = 92.0(4), γ = 92.1(5); Z = 2; calculated density 1.157 g/cm3. The structure has been refined by block-matrix, least-squares methods using 4358 independent reflections to a standard unweighted R factor of 4.9%. 相似文献