全文获取类型
收费全文 | 139篇 |
免费 | 12篇 |
国内免费 | 1篇 |
专业分类
化学 | 96篇 |
晶体学 | 2篇 |
数学 | 23篇 |
物理学 | 31篇 |
出版年
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 12篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 13篇 |
2015年 | 12篇 |
2014年 | 5篇 |
2013年 | 5篇 |
2012年 | 10篇 |
2011年 | 2篇 |
2010年 | 2篇 |
2009年 | 5篇 |
2008年 | 8篇 |
2007年 | 10篇 |
2006年 | 7篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2000年 | 2篇 |
1998年 | 1篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1981年 | 2篇 |
1979年 | 3篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1962年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有152条查询结果,搜索用时 15 毫秒
71.
72.
Copula convergence theorems for tail events 总被引:3,自引:0,他引:3
Tail dependence is studied from a distributional point of view by means of appropriate copulae. We derive similar results to the famous Pickands–Balkema–de Haan Theorem of Extreme Value Theory. Under regularity conditions, it is shown that the Clayton copula plays among the family of archimedean copulae the role of the generalized Pareto distribution. The practical usefulness of the results is illustrated in the analysis of stock market data. 相似文献
73.
Juri Ugolotti 《Journal of organometallic chemistry》2011,696(6):1184-1188
Treatment of R2Si(CC-SiMe3)2 [1a (Me), 1b (Ph)] with HB(C6F5)2 at low temperature (253 K (a), 273 K (b)) gives the -B(C6F5)2 substituted silacyclobutene products (4a,b) under kinetic control. Upon warming to room temperature they disappear to form the thermodynamically favoured isomeric silole derivatives (2a,b). Similar treatment of Me2Si(CC-R1)2 [5a (R1 = Ph), 5b (R1 = tert-butyl) with HB(C6F5)2 at room temperature gave the stable -B(C6F5)2 substituted silacyclobutene derivatives 6 and 7, respectively. Subsequent photolysis resulted in a Z- to E-isomerization of the substituted exocyclic CC double bonds in these products. The silacyclobutene derivative E-6 was characterized by an X-ray crystal structure analysis. 相似文献
74.
We show that the existence of a pair of zero-energy modes bound to a vortex carrying a π-flux is a generic feature of the topologically non-trivial phase of the M–B model, which was introduced to describe the topological band insulator in HgTe quantum wells. We explicitly find the form of the zero-energy states of the corresponding Dirac equation, which contains a novel momentum-dependent mass term and describes a generic topological transition in a band insulator. The obtained modes are exponentially localized in the vortex-core, with the dependence of characteristic length on the parameters of the model matching the dependence extracted from a lattice version of the model. We consider in full generality the short-distance regularization of the vector potential of the vortex, and show that a particular choice yields the modes localized and simultaneously regular at the origin. Finally, we also discuss a realization of two-dimensional spin-charge separation through the vortex zero-modes. 相似文献
75.
76.
Peroković Vesna Petrović Car Željka Usenik Andrea Opačak-Bernardi Teuta Jurić Andrea Tomić Srđanka 《Molecular diversity》2020,24(1):253-263
Molecular Diversity - Pyran-4-one (maltol, kojic acid and chlorokojic acid 1) esters of adamantan-1-ylacetic acid were prepared through efficient synthetic routes in good yields and evaluated for... 相似文献
77.
78.
Frank Dickmann Jürgen Falkner Wilfried Gunia Jochen Hampe Michael Hausmann Alexander Herrmann Nick Kepper Tobias A. Knoch Svenja Lauterbach Jörg Lippert Kathrin Peter Eberhard Schmitt Ulrich Schwardmann Juri Solodenko Dietmar Sommerfeld Thomas Steinke Anette Weisbecker Ulrich Sax 《Journal of computational science》2012,3(5):280-297
The project Services@MediGRID consortium established a tool set of grid-based biomedical services since 2008. The services are related to genetic analysis, genome data visualization, and pharmacokinetic modeling. Furthermore, business concepts for these services have been examined which are supported by an accounting and billing service. While the tools cover a whole service chain for biomedicine, the business concepts are rather heterogeneous. However, the overall addressed target market areas show promising potential. In addition, a structured coaching process reduces friction in the technology transfer from grid computing to biomedicine. This should be considered for similar future endeavors. 相似文献
79.
Nuwandi M. Ariyasingha Dr. Baptiste Joalland Hassan R. Younes Dr. Oleg G. Salnikov Dr. Nikita V. Chukanov Dr. Kirill V. Kovtunov Dr. Larisa M. Kovtunova Prof. Valerii I. Bukhtiyarov Prof. Igor V. Koptyug Prof. Juri G. Gelovani Prof. Eduard Y. Chekmenev 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(60):13621-13626
The growing interest in magnetic resonance imaging (MRI) for assessing regional lung function relies on the use of nuclear spin hyperpolarized gas as a contrast agent. The long gas-phase lifetimes of hyperpolarized 129Xe make this inhalable contrast agent acceptable for clinical research today despite limitations such as high cost, low throughput of production and challenges of 129Xe imaging on clinical MRI scanners, which are normally equipped with proton detection only. We report on low-cost and high-throughput preparation of proton-hyperpolarized diethyl ether, which can be potentially employed for pulmonary imaging with a nontoxic, simple, and sensitive overall strategy using proton detection commonly available on all clinical MRI scanners. Diethyl ether is hyperpolarized by pairwise parahydrogen addition to vinyl ethyl ether and characterized by 1H NMR spectroscopy. Proton polarization levels exceeding 8 % are achieved at near complete chemical conversion within seconds, causing the activation of radio amplification by stimulated emission radiation (RASER) throughout detection. Although gas-phase T1 relaxation of hyperpolarized diethyl ether (at partial pressure of 0.5 bar) is very efficient, with T1 of ca. 1.2 second, we demonstrate that, at low magnetic fields, the use of long-lived singlet states created via pairwise parahydrogen addition extends the relaxation decay by approximately threefold, paving the way to bioimaging applications and beyond. 相似文献
80.