全文获取类型
收费全文 | 116篇 |
免费 | 3篇 |
专业分类
化学 | 84篇 |
晶体学 | 3篇 |
力学 | 4篇 |
数学 | 19篇 |
物理学 | 9篇 |
出版年
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 4篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 3篇 |
2012年 | 7篇 |
2011年 | 6篇 |
2010年 | 6篇 |
2009年 | 4篇 |
2008年 | 1篇 |
2007年 | 7篇 |
2006年 | 5篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1996年 | 3篇 |
1994年 | 1篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1963年 | 1篇 |
1928年 | 3篇 |
1877年 | 2篇 |
1868年 | 1篇 |
排序方式: 共有119条查询结果,搜索用时 31 毫秒
11.
We demonstrate a technique, named dual structured laser illumination planar imaging (SLIPI), capable of acquiring depth-resolved images of the extinction coefficient. This is achieved by first suppressing the multiply scattered light intensity and then measuring the intensity reduction caused by signal attenuation between two laser sheets separated by Δz mm. Unlike other methods also able to measure this quantity, the presented approach is based solely on side-scattering detection. The main advantages of dual SLIPI is that it accounts for multiple scattering, provides two-dimensional information, and can be applied on inhomogeneous media. 相似文献
12.
Colorectal cancer is currently the third most common malignancy in the world. Patients have excellent prognosis following surgical resection if their tumour is still localized at diagnosis. By contrast, once the tumour has started to metastasize, prognosis is much poorer. Accurate early detection can therefore significantly reduce the mortality from this disease. However, current tests either lack the required sensitivity and selectivity or are costly and invasive. Improved biomarkers, or panels of biomarkers, are therefore urgently required. We have addressed current screening strategies and potential protein biomarkers that have been proposed. The role of both discovery and hypothesis-driven proteomics approaches for biomarker discovery and validation is discussed. Using such approaches we show how multiple reaction monitoring (MRM) can be successfully developed and used for quantitative multiplexed analysis of potential faecal biomarkers. 相似文献
13.
We introduce the notion of predicted decrease approximation (PDA) for constrained convex optimization, a flexible framework which includes as special cases known algorithms such as generalized conditional gradient, proximal gradient, greedy coordinate descent for separable constraints and working set methods for linear equality constraints with bounds. The new scheme allows the development of a unified convergence analysis for these methods. We further consider a partially strongly convex nonsmooth model and show that dual application of PDA-based methods yields new sublinear convergence rate estimates in terms of both primal and dual objectives. As an example of an application, we provide an explicit working set selection rule for SMO-type methods for training the support vector machine with an improved primal convergence analysis. 相似文献
14.
We denote by ℳ
R
n
the test neighbourhood sufficient to extract the Euclidean Medial Axis of any n-dimensional discrete shape whose inner radius is no greater than R. In this paper, we study properties of discrete Euclidean disks overlappings so as to prove that in any given dimension n, ℳ
R
n
tends to the set of visible vectors as R tends to infinity. 相似文献
15.
Valérie Samouillan Edouard Lamy Jany Dandurand Alexandrine Foucault-Bertaud Corinne Chareyre Colette Lacabanne Philippe Charpiot 《Journal of Non》2009,355(14-15):830-835
The thermal and dielectric properties of the elastin network were investigated in arteries cultured with physiological and pathological concentrations of homocysteine, an aminoacid responsible of histological impairments in human arteries. The glass transition of this amorphous protein was investigated by Differential Scanning Calorimetry (DSC). To explore the molecular dynamics of the elastin network in the nanometer range, we used Thermally Stimulated Currents (TSC), a dielectric technique running at low frequency and measuring the dipolar reorientations in proteins subjected to a static electrical field. Combining TSC and DSC experiments with determination of the activation parameters of relaxation times reveals the molecular mobility of the proteins. The major differences in the relaxation behavior of elastin between arteries cultured with physiological and pathological concentrations of homocysteine are discussed. 相似文献
16.
In our previous works a new method of conjugate directions for large-scale unconstrained minimization problems has been presented [1, 2]. In the paper this algorithm is extended to minimization problems with bound constraints. Because the linear minimization along the newly found conjugate vector is not needed for constructing the next conjugate vector and one arbitrarily step-size (not necessarily the optimal one) is calculated along this conjugate direction, we are able to incorporate naturally the bound constraints into the algorithm. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
17.
Bernard Béguin Edouard Garbowski Stefan Dietrich Peter Michel Primet 《Reaction Kinetics and Catalysis Letters》1996,59(2):253-262
Monometallic and bimetallic catalysts based on palladium and copper deposited on a spinel carrier have been investigated in the catalytic combustion of methane. Great differences were found in catalytic activity, according to the sequence Pd/MgAl2O4>CuO–Pd/MgAl2O4>Pd–CuO/MgAl2O4>CuO/MgAl2O4. They were explained by changes in surface composition of the catalysts. In the case of bimetallic catalysts the metallic surface is preferentially enriched in copper, which acts as a diluting agent for the Pd atom ensembles. As a consequence, the adsorption of reactants is limited and the catalysts so obtained behave like copper slightly doped with palladium. 相似文献
18.
Günther Ohloff Wolfgang Giersch Karl H. Schulte-Elte Paul Enggist Edouard Demole 《Helvetica chimica acta》1980,63(6):1582-1588
Following a known procedure, a mixture of (?)-(2S,3R)- and (+)-(2R,3R)-2,3-epoxy-citronellols ( 5 ) was prepared from (?)-(R)-linalool ( 3 ) via epoxy alcohol 4 and then reduced to (?)-(R)-3-hydroxy-citronellol ( 6 ). Sensitized photooxygenation of (?)-(R)-diol 6 led in part to (?)-(R)-triol 8 which was cyclodehydrated by dilute acid to a mixture of diastereoisomeric tetrahydropyran-4-ols 9 and 10 . Dehydration of hydroxy ethers 9 and 10 afforded (?)-(S)-nerol oxide ( 11 ) and (+)-(R)-nerol oxide ( 12 ), respectively, with an optical purity of 91%. Nerol oxide isolated from Bulgarian rose oil (0.038%) proved to be racemic. These results shed some light on the formation of nerol oxide in plants. 相似文献
19.
Mathematical Programming - Modern problems in AI or in numerical analysis require nonsmooth approaches with a flexible calculus. We introduce generalized derivatives called conservative fields for... 相似文献
20.