全文获取类型
收费全文 | 300篇 |
免费 | 3篇 |
国内免费 | 1篇 |
专业分类
化学 | 243篇 |
晶体学 | 1篇 |
力学 | 4篇 |
数学 | 29篇 |
物理学 | 27篇 |
出版年
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 12篇 |
2020年 | 10篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 10篇 |
2013年 | 23篇 |
2012年 | 16篇 |
2011年 | 14篇 |
2010年 | 12篇 |
2009年 | 16篇 |
2008年 | 6篇 |
2007年 | 9篇 |
2006年 | 7篇 |
2005年 | 9篇 |
2004年 | 15篇 |
2003年 | 14篇 |
2002年 | 15篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 10篇 |
1992年 | 1篇 |
1991年 | 5篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 7篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有304条查询结果,搜索用时 31 毫秒
211.
Siebold M Leidich P Bertini M Deflorio G Feldmann J Krupp EM Halmschlager E Woodward S 《Analytical and bioanalytical chemistry》2012,402(10):3323-3331
Element distribution in the bark of two 20-year-old clones of Picea sitchensis following wounding was studied using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Bark was sampled
at 0, 3, and 43 days after wounding and analysed using a focused Nd:YAG laser (266 nm). Intensities of 13 C, 25Mg, 27Al, 31P, 32S, 39K, 48Ca, 55Mn, 57Fe, 63Cu and 64Zn were measured by ICP-MS to study elemental distribution across the bark samples during the wound repair process. A clear
accumulation of Mg, P and K at the boundary zone between the lesion and healthy tissue was detected in the wounded samples
and was more distinctive at 43 than at 3 days after treatment. This zone of accumulation mapped onto the position of formation
of the ligno-suberised boundary zone and differentiation of the wound periderm. These accumulations suggest major roles for
Mg, P and K in the non-specific response of Sitka spruce both to wounding, possibly as co-factors to enzymes and energy utilisation.
The LA-ICP-MS method developed in this work proved useful to study spatial element distribution across bark samples and has
great potential for applications in other areas of plant pathology research. 相似文献
212.
At the SYnchrotron Radiation for MEdical Physics (SYRMEP) beamline of Elettra, a widespread research activity in bio-medical imaging has been developed since 1997 [1]. The core program carried out by the SYRMEP research team concerns the use of synchrotron radiation (SR) for mammography in the effort of improving image diagnostic quality innovating the imaging technique and the detection system. 相似文献
213.
Giuliana Regoli 《Journal of multivariate analysis》2009,100(6):1261-1269
We introduce a class of absolutely continuous bivariate exponential distributions, generated from quadratic forms of standard multivariate normal variates.This class is quite flexible and tractable, since it is regulated by two parameters only, derived from the matrices of the quadratic forms: the correlation and the correlation of the squares of marginal components. A simple representation of the whole class is given in terms of 4-dimensional matrices. Integral forms allow evaluating the distribution function and the density function in most of the cases.The class is introduced as a subclass of bivariate distributions with chi-square marginals; bounds for the dimension of the generating normal variable are underlined in the general case.Finally, we sketch the extension to the multivariate case. 相似文献
214.
The 17O NMR spectra of some esters are discussed and are correlated with 13C NMR chemical shift and IR carbonyl streching band data. 相似文献
215.
216.
Fontana A Tramice A Cutignano A D'Ippolito G Gavagnin M Cimino G 《The Journal of organic chemistry》2003,68(6):2405-2409
Biogenesis of the enantiomeric sesquiterpenes 1 and 5 of the marine nudibranch Doriopsilla areolata was investigated by feeding of [1-(13)C]glucose, [1,2-(13)C(2)]glucose, and [1,2-(13)C(2)]acetate. Evidence is presented that supports de novo origin of both compounds via mevalonic acid. 相似文献
217.
218.
Giuliana Criscuolo Giuseppe Mastroianni Donatella Occorsio 《Numerische Mathematik》1991,60(1):195-218
Summary The authors construct some extended interpolation formulae to approximate the derivatives of a function in uniform norm. They prove theorems on uniform convergence and give estimates of pointwise type and of simultaneous approximation.This material is based upon work supported by the Italian Research Council (first and second authors), and by the Ministero dell'Università e della Ricerca Scientifica e Tecnologica (second and third author). 相似文献
219.
220.
d'Ippolito G Cutignano A Briante R Febbraio F Cimino G Fontana A 《Organic & biomolecular chemistry》2005,3(22):4065-4070
An unprecedented series of C16 oxylipins (1-8) has been characterized from the marine diatom Thalassiosira rotula. Absolute stereochemistry of the major alcohols 1 and 3 was determined to be 9S by spectroscopic and chemical methods. All the described products are formally derived by unprecedented enzymatic oxidation of C16 fatty acids. Conversion of hexadeca-6,9,12-trienoic acid (C16:3 omega-4) into 3 unequivocally established the occurrence of (at least) a specific 9S-oxygenase activity. To the best of our knowledge, the present data reveal for the first time the existence of an organic network of oxygenase-mediated transformations that require C16 fatty acids as substrates in living cells. 相似文献