全文获取类型
收费全文 | 527篇 |
免费 | 16篇 |
专业分类
化学 | 394篇 |
晶体学 | 1篇 |
力学 | 15篇 |
数学 | 65篇 |
物理学 | 68篇 |
出版年
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 10篇 |
2018年 | 7篇 |
2017年 | 9篇 |
2016年 | 17篇 |
2015年 | 12篇 |
2014年 | 26篇 |
2013年 | 25篇 |
2012年 | 34篇 |
2011年 | 28篇 |
2010年 | 18篇 |
2009年 | 20篇 |
2008年 | 36篇 |
2007年 | 33篇 |
2006年 | 35篇 |
2005年 | 42篇 |
2004年 | 28篇 |
2003年 | 25篇 |
2002年 | 21篇 |
2001年 | 9篇 |
2000年 | 2篇 |
1999年 | 7篇 |
1997年 | 7篇 |
1996年 | 4篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1982年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1943年 | 1篇 |
1939年 | 2篇 |
1938年 | 1篇 |
1937年 | 4篇 |
1935年 | 4篇 |
1934年 | 4篇 |
1933年 | 4篇 |
1932年 | 3篇 |
1931年 | 5篇 |
1930年 | 4篇 |
1927年 | 4篇 |
1926年 | 2篇 |
1925年 | 1篇 |
1924年 | 3篇 |
1923年 | 1篇 |
1922年 | 1篇 |
1918年 | 2篇 |
排序方式: 共有543条查询结果,搜索用时 15 毫秒
41.
E. Barnitzke D. Brunton J. A. Scherrer G. E. F. Lundell H. Gehle E. Hildebrandt und E. Schiller 《Fresenius' Journal of Analytical Chemistry》1933,94(7-8):257-259
Ohne Zusammenfassung 相似文献
42.
43.
G. E. F. Lundell H. B. Knowles und Weber 《Fresenius' Journal of Analytical Chemistry》1926,68(7-8):306-309
Ohne Zusammenfassung 相似文献
44.
Fredrik Kuivinen 《Discrete Optimization》2011,8(3):459-477
Let (L;?,?) be a finite lattice and let n be a positive integer. A function f:Ln→R is said to be submodular if for all . In this article we study submodular functions when L is a diamond. Given oracle access to f we are interested in finding such that as efficiently as possible. We establish
•
a min–max theorem, which states that the minimum of the submodular function is equal to the maximum of a certain function defined over a certain polyhedron; and •
a good characterisation of the minimisation problem, i.e., we show that given an oracle for computing a submodular f:Ln→Z and an integer m such that , there is a proof of this fact which can be verified in time polynomial in n and ; and •
a pseudopolynomial-time algorithm for the minimisation problem, i.e., given an oracle for computing a submodular f:Ln→Z one can find in time bounded by a polynomial in n and .
45.
Ma G Gran F Jacobsen F Agerkvist F 《The Journal of the Acoustical Society of America》2011,130(1):350-363
Feedback whistling is a severe problem with hearing aids. A typical acoustical feedback path represents a wave propagation path from the receiver to the microphone and includes many complicated effects among which some are invariant or nearly invariant for all users and in all acoustical environments given a specific type of hearing aids. Based on this observation, a feedback path model that consists of an invariant model and a variant model is proposed. A common-acoustical-pole and zero model-based approach and an iterative least-square search-based approach are used to extract the invariant model from a set of impulse responses of the feedback paths. A hybrid approach combining the two methods is also proposed. The general properties of the three methods are studied using artificial datasets, and the methods are cross-validated using the measured feedback paths. The results show that the proposed hybrid method gives the best overall performance, and the extracted invariant model is effective in modeling the feedback path. 相似文献
46.
Lightweight building systems in general suffer from poor sound insulation, especially in the low frequency region. Since no reliable mathematical models that can predict the impact sound pressure level exists, the lightweight building design is to a high extent based upon previous experience and upon measurements. A special difficulty is related to experimental measurements since the variation among identical units must not be neglected. A modern volume based lightweight wooden building concept has here been tested by numerous well controlled measurements, in laboratory as well as in more field like conditions. The volume construction technique offers new possibilities and challenges to improve sound insulation in light weight timber construction. The main purpose was to investigate how different constructional solutions in the floor, like plaster board, mineral wool, elastic glue, dividing board, floating floor etc., affect the sound insulation. Many of the tested modifications resulted in only marginally changed impact sound pressure level but parameters that substantially can improve the sound insulation were found in using elastic glue to mount the floor boards, to install extra board layers and to use floating floors. 相似文献
47.
Cristian Bodin Fredrik Mauritzson Rob Horsefield Anna Aagaard Hongwei Guo Linda Öster Lisa Wissler Margareta Ek 《Journal of synchrotron radiation》2012,19(2):288-289
Currently there is no rack system for the long‐term storage of SPINE pucks in spite of their commercial availability and heavy usage at the ESRF. The only way to store pucks is in transport dewar canisters which presents a number of limitations and drawbacks. Here a simple affordable rack for storing SPINE pucks is described, which we believe is accessible to not only synchrotrons but also both academic and industrial research laboratories. 相似文献
48.
Emil Byström Anna Nordborg Fredrik Limé Ngoc Phuoc Dinh Knut Irgum 《Journal of separation science》2010,33(11):1563-1570
A combined surface activation and “grafting to” strategy was developed to convert divinylbenzene particles into weak cation exchangers suitable for protein separation. The initial activation step was based on plasma modification with bromoform, which rendered the particles amenable to further reaction with nucleophiles by introducing Br to a surface content of 11.2 atom‐%, as determined by X‐ray photoelectron spectroscopy. Grafting of thiol‐terminated glydicyl methacrylate telomers to freshly plasma activated surfaces was accomplished without the use of added initiator, and the grafting was verified both by reduction in bromine content and the appearance of sulfur‐carbon linkages, showing that the surface grafts were covalently bonded. Following grafting the attached glydicyl methacrylate telomer tentacles were further modified by a two‐step procedure involving hydrolysis to 2,3‐hydroxypropyl groups and conversion of hydroxyl groups to carboxylate functionality by succinic anhydride. The final material was capable of baseline separating four model proteins in 3 min by gradient cation exchange chromatography in a fully aqueous eluent. 相似文献
49.
R. F. Le Guyon R. M. May W. M. Mc Nabb A. v. Endrédy H. H. Willard A. W. Boldyreff G. E. F. Lundell J. I. Hoffman W. Blum C. M. Johnson O. Kuhnt R. Ariano R. P. Hudson F. Graziani L. Losana H. Burton-Smith W. F. Pond L. E. Pitzer B. Salkin K. Hinsberg D. Laszlo und G. Schikorr 《Fresenius' Journal of Analytical Chemistry》1931,85(7-8):286-303
Ohne Zusammenfassung 相似文献
50.