全文获取类型
收费全文 | 124篇 |
免费 | 4篇 |
专业分类
化学 | 31篇 |
力学 | 1篇 |
数学 | 81篇 |
物理学 | 15篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2014年 | 2篇 |
2013年 | 6篇 |
2012年 | 4篇 |
2011年 | 13篇 |
2010年 | 3篇 |
2009年 | 6篇 |
2008年 | 3篇 |
2007年 | 3篇 |
2006年 | 10篇 |
2005年 | 1篇 |
2004年 | 7篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1978年 | 2篇 |
1976年 | 3篇 |
1972年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有128条查询结果,搜索用时 0 毫秒
1.
After briefly renewing toxicological data on germanium compounds, the authors report on the subchronic oral toxicity of carboxyethylgermanium sesquioxide in rats. During six months, male and female animals received 1 g kg?1. day?1. No particular toxic symptoms, and no behaviour problems except a small decrease of body weight in male rats, at the end of the six-month experimentation period, were observed. A significant decrease of erythropoiesis and some significant changes in leucocyte ratios were demonstrated. The main marked effect was a moderate renal dysfunction characterized by a tubular disease with the presence of cylinders, swelling of tubulus cells and flocculus deposits. Germanium urinary excretion was constant and linked to the received dose. Six months later, no preferential accumulation in organs was evident. 相似文献
2.
Amir Averbuch Valery Zheludev Pekka Neittaanmäki Pekka Wartiainen Kari Huoman Kim Janson 《Applied Acoustics》2011,(1):22-34
We present a robust algorithm to detect the arrival of a boat of a certain type when other background noises are present. It is done via the analysis of its acoustic signature against an existing database of recorded and processed acoustic signals. We characterize the signals by the distribution of their energies among blocks of wavelet packet coefficients. To derive the acoustic signature of the boat of interest, we use the Best Discriminant Basis method. The decision is made by combining the answers from the Linear Discriminant Analysis (LDA) classifier and from the Classification and Regression Trees (CART) that is also accompanied with an additional unit, called Aisles, that reduces false alarms rate. The proposed algorithm is a generic solution for process control that is based on a learning phase (training) followed by an automatic real time detection while minimizing the false alarms rate. 相似文献
3.
Svante Janson 《Acta Appl Math》1994,34(1-2):7-15
We give an overview of the Stein-Chen method for establishing Poisson approximations of various random variables. Couplings of certain variables are used to gives explicit bounds for the total variation distance between the distribution of a random variable and a Poisson variable. Some applications are given. In some cases, explicit couplings may be used to obtain good estimates; in other applications it suffices to show the existence of couplings with certain monotonicity properties.Supported by the Göran Gustafsson Foundation for Research in Natural Sciences and Medicine. 相似文献
4.
In this paper we study the component structure of random graphs with independence between the edges. Under mild assumptions,
we determine whether there is a giant component, and find its asymptotic size when it exists. We assume that the sequence
of matrices of edge probabilities converges to an appropriate limit object (a kernel), but only in a very weak sense, namely
in the cut metric. Our results thus generalize previous results on the phase transition in the already very general inhomogeneous
random graph model introduced by the present authors in Random Struct. Algorithms 31:3–122 (2007), as well as related results of Bollobás, Borgs, Chayes and Riordan (Ann. Probab. 38:150–183, 2010), all of which involve considerably stronger assumptions. We also prove corresponding results for random hypergraphs; these
generalize our results on the phase transition in inhomogeneous random graphs with clustering (Random Struct. Algorithms,
2010, to appear). 相似文献
5.
Svante Janson 《Annals of Combinatorics》2009,12(4):417-447
We study the space requirements of a sorting algorithm where only items that at the end will be adjacent are kept together. This is equivalent to the following combinatorial problem: Consider a string of fixed length n that starts as a string of 0’s, and then evolves by changing each 0 to 1, with the n changes done in random order. What is the maximal number of runs of 1’s? We give asymptotic results for the distribution and mean. It turns out that, as in many problems involving a maximum, the maximum is asymptotically normal, with fluctuations of order n 1/2, and to the first order well approximated by the number of runs at the instance when the expectation is maximized, in this case when half the elements have changed to 1; there is also a second order term of order n 1/3. We also treat some variations, including priority queues and sock-sorting. The proofs use methods originally developed for random graphs. 相似文献
6.
Regio- and stereoselective Cu-catalyzed addition of the above hypervalent iodine reagent to alkynes and alkenes was achieved. In the presence of CuI, the reaction is suitable to perform trifluoromethyl-benzoyloxylation and trifluoromethyl-halogenation of alkenes and alkynes. Electron-donating substituents accelerate the process, and alkenes react faster than alkynes emphasizing the electrophilic character of the addition reaction. 相似文献
7.
High-speed counter-current chromatography using a new liquid-liquid/solid three-phase system was used for the separation of the polyphenols corilagin and geraniin from a crude extract of Geranium wilfordii Maxim in one step. The optimized three-phase system was composed of n-hexane/ethyl acetate/methanol/acetic acid/water and to which was added 10-μm average diameter microspheres of cross-linked 12% agarose at the ratio of 0.2:10:2:1:5 and 0.1 g/mL, respectively. The purities of geraniin and corilagin were 82 and 90%, which were determined by HPLC at 280 nm. A 14.5 and 7 mg of geraniin and corilagin were purified from 160 mg crude extract with the yields of 70 and 78%, respectively. 相似文献
8.
Min Gao Xiaolei Wang Ming Gu Zhiguo Su Ye Wang Jan‐Christer Janson 《Journal of separation science》2011,34(15):1853-1858
A porous polyamide resin is shown to possess hydrogen bond acceptor properties suitable for the separation of polyphenolic solutes such as phenolic acids, flavonols and flavonoids. The separation is achieved in the presence of solvent mixtures of acetic acid and ethanol. The extent of hydrogen bond adsorption is reviewed based on data obtained from the elution behaviour of a variety of simple polyphenolic solutes. Polyamide adsorption chromatography was applied for the purification of resveratrol and polydatin from Polygonum cuspidatum Sieb. & Zucc. 相似文献
9.
(-)-Epigallocatechin gallate (EGCG) was purified in one step from a green tea polyphenol (GTP) crude extract by adsorption chromatography on a Superose 12 HR 10/30 column. The mobile phase used was a mixture of acetonitrile and water with an optimum mobile phase compositions regarding purity, recovery and separation time of 78/22 (v/v). Maximum practical sample loading was 100 mg GTP per run (corresponding to 4.2 mg/ml Superose). An EGCG purity of 99% with recoveries in the range 60-65% was achieved in one step directly from the crude GTP extract. Full column regeneration was obtained using solvents in the following order: 0.5 M NaOH, distilled water and 30% acetic acid. 相似文献
10.
Svante Janson 《Probability Theory and Related Fields》2006,134(3):417-452
We study a generalized Pólya urn with balls of two colours and a triangular replacement matrix; the urn is not required to
be balanced. We prove limit theorems describing the asymptotic distribution of the composition of the urn after a long time.
Several different types of asymptotics appear, depending on the ratio of the diagonal elements in the replacement matrix;
the limit laws include normal, stable and Mittag-Leffler distributions as well as some less familiar ones. The results are
in some cases similar to, but in other cases strikingly different from, the results for irreducible replacement matrices. 相似文献