全文获取类型
收费全文 | 1159篇 |
免费 | 69篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 415篇 |
金属工艺 | 6篇 |
机械仪表 | 27篇 |
建筑科学 | 53篇 |
矿业工程 | 1篇 |
能源动力 | 44篇 |
轻工业 | 132篇 |
水利工程 | 6篇 |
石油天然气 | 1篇 |
无线电 | 79篇 |
一般工业技术 | 198篇 |
冶金工业 | 46篇 |
原子能技术 | 18篇 |
自动化技术 | 191篇 |
出版年
2024年 | 2篇 |
2023年 | 14篇 |
2022年 | 55篇 |
2021年 | 61篇 |
2020年 | 31篇 |
2019年 | 25篇 |
2018年 | 30篇 |
2017年 | 35篇 |
2016年 | 49篇 |
2015年 | 34篇 |
2014年 | 41篇 |
2013年 | 82篇 |
2012年 | 76篇 |
2011年 | 113篇 |
2010年 | 64篇 |
2009年 | 78篇 |
2008年 | 66篇 |
2007年 | 47篇 |
2006年 | 39篇 |
2005年 | 38篇 |
2004年 | 33篇 |
2003年 | 30篇 |
2002年 | 37篇 |
2001年 | 16篇 |
2000年 | 15篇 |
1999年 | 11篇 |
1998年 | 20篇 |
1997年 | 12篇 |
1996年 | 9篇 |
1995年 | 12篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 9篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1928年 | 2篇 |
1901年 | 1篇 |
排序方式: 共有1231条查询结果,搜索用时 15 毫秒
71.
Paola Milla Franca Viola Maurizio Ceruti Flavio Rocco Luigi Cattel Gianni Balliano 《Lipids》1999,34(7):681-688
19-Azasqualene-2,3-epoxide was more inhibitory than the corresponding N-oxide against 2,3-oxidosqualene cyclase (OSC) solubilized from Saccharomyces cerevisiae (IC50 7±2 and 25±5 μM, respectively). Both compounds showed a reversible, noncompetitive-type inhibition on solubilized OSC. Different
inhibitory properties between the compounds were especially evident when measuring [14C]acetate incorporation into nonsaponifiable lipids extracted from treated cells. In cells treated with 19-azasqualene-2,3-epoxide
at 30 μM, the radioactivity associated with the oxidosqualene fraction, which was negligible in the controls, rose to over
40% of the nonsaponifiable lipids, whereas it remained at a slightly appreciable level in cells treated with the N-oxide derivative under the same conditions. 19-Azasqualene-2,3-epoxide was also more effective than the N-oxide as a cell growth inhibitor (minimal concentration of compound needed to inhibit yeast growth: 45 and >100 μM, respectively).
The two inhibitors underwent different metabolic fates in the yeast: while 19-azasqualene-2,3-epoxide did not undergo any
transformation, its N-oxide was actively reduced to the corresponding amine in whole and in “ultrasonically stimulated” cells. The N-oxide reductases responsible for this transformation appear to be largely confined within the microsomal fractions and require
NADPH for their activity. A possible relationship between the inhibitory properties of the two compounds and their metabolic
fates is discussed. 相似文献
72.
This paper focuses on the problem of key‐frames coding and proposes a new promising approach based on the use of fractals. The summary, made of a set of key‐frames selected from a full‐length video sequence, is coded by using a 3D fractal scheme. This allows the video presentation tool to expand the video sequence in a “natural” way by using the property of the fractals to reproduce the signal at several resolutions. This feature represents an important novelty of this work with respect to the alternative approaches, which mainly focus on the compression ratio without taking into account the presentation aspect of the video summary. In devising the coding scheme, we have taken care of the computational complexity inherent in fractal coding. Accordingly, the key‐frames are first wavelet transformed, and the fractal coding is then applied to each subband to reduce the search range. Experimental results show the effectiveness of the proposed approach. 相似文献
73.
74.
Giulia Bernardini Maurizio Comanducci Stefania Bambini Giovanni Renzone Andrea Scaloni Giovanna Morelli Mark Achtman Giulio Ratti Annalisa Santucci 《Proteomics. Clinical applications》2009,3(10):1251-1254
We previously described the first reference map for the proteome of one strain of serogroup A Neisseria meningitidis (MenA), a major cause of epidemic meningitis in humans. As a preliminary finding, in that work we noted that 2‐DE protein maps of closely related MenA isolates from different epidemics spreads could be easily compared to detect minor differences and that 2‐DE phenotypes attributable to the well‐known epidemiological marker tbpB agreed with the genoclouds model of MenA epidemiological variation during pandemic waves. We explored here the possibility that an extended comparative study of 2‐DE maps of isolates representative of the nine genoclouds described by Achtman and collaborators could be used to discriminate between strains otherwise undistinguishable. We showed the example of 14 proteins with different 2‐DE spot patterns in different genoclouds that could be considered as putative tracers for alike‐strains discrimination. We introduce the novel concept that comparative proteomics can be useful in identifying new epidemiological markers for N. meningitidis. 相似文献
75.
Mauro Ciappa Alexander Koschik Maurizio Dapor Wolfgang Fichtner 《Microelectronics Reliability》2010,50(9-11):1407-1412
Modeling of critical dimensions scanning electron microscopy with sub-nanometer uncertainty is required to provide a metrics and to avoid yield loss in the processing of advanced CMOS technologies. In this paper, a new approach is proposed, which includes a new Monte Carlo scheme, a new Monte Carlo code, as well as the coupling with electrostatic fields to take into account self-charging effects. 相似文献
76.
Elisa Tripoli Maurizio La GuardiaSanto Giammanco Danila Di MajoMarco Giammanco 《Food chemistry》2007,104(2):466-479
Epidemiological studies have shown an inverse relationship between dietary flavonoid intakes and cardiovascular diseases. Citrus fruits are the main winter fruits consumed in the Mediterranean diet, so they are the main source of dietary flavonoids. The possible beneficial effects are due, not only to the high amounts of vitamins and minerals, but also to the antioxidant properties of their flavonoids. Dietary flavonoids may help to supplement the body antioxidant defences against free radicals. These compounds’ possible beneficial effects are due to their antioxidant activity, which is related to the development of atherosclerosis and cancer, and to anti-inflammatory and antimicrobial activity. The present review summarizes the existing bibliography on biological and pharmacological studies of Citrus flavonoids, both in vitro and in vivo. 相似文献
77.
Maurizio Catino 《Cognition, Technology & Work》2009,11(4):245-253
Introduction
Defensive medicine takes place when healthcare personnel (doctors and nurses) order unnecessary treatments (positive defensive medicine) or avoid high-risk procedures or patients (negative defensive medicine) with the principle—though not exclusive—aim of reducing their expose to damages claims. This phenomenon is directly related to the significant growth in medical malpractice litigation over recent years. Defensive medicine increases the cost of healthcare and may expose patients to unnecessary risks. In fact, the large number of legal initiatives taken by patients have induced many doctors to set in place a defensive “strategy” so as to avoid placing their careers at risk. The threat of medical malpractice litigation constitutes a major obstacle to improving the reliability of healthcare organizations and patient safety. 相似文献78.
We propose mathematical programming models for solving problems arising from planning and running an energy production process based on burning biomasses. The models take into account different aspects of the problem: determination of the biomasses to produce and/or buy, transportation decisions to convey the materials to the respective plants, and plant site locations. Whereas the “running model” is linear, we propose two “planning models”, both of which are mixed-integer nonlinear programming problems. We show that a spatial branch-and-bound type algorithm applied to them is guaranteed to converge to an exact optimum in a finite number of steps. 相似文献
79.
The “antioxidant power” of a food is an expression of its capability both to defend the human organism from the action of the free radicals and to prevent degenerative disorders deriving from persistent oxidative stress. Purpose of this study is to analyse the antioxidant capacity (measured by means of the crocin bleaching method) of several samples of Sicilian red wines and to evaluate their dependency on the vintage and on the grape variety. Finally, the correlation between the single flavonoids compounds and the antioxidant capacity has been investigated. The analyses show that the antioxidant properties of red wine appear to be unequally influenced by the vintages for the different cultivars and that the correlation between antioxidant capacity and the total phenolic contents is weak. The latter can be explained by the fact that the wine’s antioxidant properties are influenced differently by each polyphenolic molecule. 相似文献
80.
Sergio M. Bonesi Esther Carbonell Hermenegildo Garcia Maurizio Fagnoni Angelo Albini 《Applied catalysis. B, Environmental》2008,79(4):368-375
Solid photocatalysts in which the 2,4,6-triphenylpyrylium (TP) or 2,4,6-triphenylthiapyrylium cation (TTP) are encapsulated within zeolite Y or deposited on mesoporous silica are used as photosensitizers for the oxidation of sulfides, both aromatic and aliphatic, in solvents of various polarity. Contrary to the same cations in solution, these solid sensitizers are not significantly degraded during operation. An effective oxygenation takes place leading to sulfoxides, disulfides, sulfinic and sulfenic esters as well as sulfonic acids. This large scope method shows a limited dependence on the substrate structure and on conditions and is suitable for the abatement of sulfur-containing pollutants. 相似文献