全文获取类型
收费全文 | 532篇 |
免费 | 0篇 |
国内免费 | 2篇 |
专业分类
化学 | 372篇 |
晶体学 | 1篇 |
力学 | 8篇 |
数学 | 100篇 |
物理学 | 53篇 |
出版年
2021年 | 6篇 |
2017年 | 3篇 |
2015年 | 3篇 |
2013年 | 10篇 |
2012年 | 14篇 |
2011年 | 12篇 |
2010年 | 10篇 |
2009年 | 4篇 |
2008年 | 17篇 |
2007年 | 13篇 |
2006年 | 13篇 |
2005年 | 8篇 |
2004年 | 16篇 |
2003年 | 16篇 |
2002年 | 5篇 |
2001年 | 3篇 |
1999年 | 8篇 |
1998年 | 11篇 |
1997年 | 12篇 |
1996年 | 11篇 |
1995年 | 13篇 |
1994年 | 11篇 |
1993年 | 22篇 |
1992年 | 7篇 |
1991年 | 11篇 |
1990年 | 12篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 10篇 |
1986年 | 13篇 |
1985年 | 13篇 |
1984年 | 6篇 |
1983年 | 12篇 |
1982年 | 13篇 |
1981年 | 6篇 |
1980年 | 17篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1975年 | 17篇 |
1974年 | 9篇 |
1973年 | 10篇 |
1972年 | 10篇 |
1971年 | 14篇 |
1970年 | 19篇 |
1969年 | 10篇 |
1966年 | 4篇 |
1964年 | 4篇 |
1963年 | 4篇 |
排序方式: 共有534条查询结果,搜索用时 15 毫秒
21.
Astrid Brandt Wilhelm Schwieger Karl-Heinz Bergk Paul Grabner Martin Porsch 《Crystal Research and Technology》1989,24(1):47-54
The mechanism of the thermal behaviour of Na-magadiite at a temperature range from 293–573 K was developed based on X-ray diffraction, DTA, DTL, Q-TG, and gravimetric measurements. A structure model (BRANDT et al.) previously proposed was additionally used. It is possible to show that there probably is a connection between the typical modifications of basal spacing and significant shiftings of silicate sheets. Different steps of dehydration, decrystallization and structure variations can be ascribed to the several thermal transitions. The results depend on sample treatment such as the existent or not existent solid-water vapour interaction and the establishment of equilibrium. It seems that there is a predominance of the first mentioned influence. 相似文献
22.
23.
Roman Böttger Karl-Heinz Heinig Lothar Bischoff Bartosz Liedke Stefan Facsko 《Applied Physics A: Materials Science & Processing》2013,113(1):53-59
We show that hole patterns and sponge-like layers at irradiated Ge surfaces originate from the same driving force, namely the kinetics of ion beam induced defects in the amorphous Ge surface layer. Ge hole patterns reported earlier for irradiation with low energy (5 keV) Ga+ ions were reproduced for low energy Bi+ but also for Ge+ self-irradiation, which proves that the dominating driving force for morphology evolution cannot originate from the implanted impurities. At higher ion energies the well-known formation of sponge-like Ge surface layers after heavy ion irradiation was found for Bi+ irradiation and Ge+ self-irradiation, also. The transition from smooth surfaces via hole patterns to sponge-like morphologies with increasing ion energies was studied in detail. A model based on the kinetics of ion beam induced defects was developed and implemented in 3D kinetic Monte Carlo simulations, which reproduce the transition from hole patterns to sponge-like layers with increasing ion energy. 相似文献
24.
Glasfibre structures feature high potentials for optimization and substitution of conventional materials like steel and aluminum and their alloys. The paper deals with the insertion of glasfibre trusses into thin glasfibre structures to reinforce them. The effective material properties of the glasfibre structures were estimated by experiments and simulations. Furthermore the Young's modulus of the trusses was obtained by bending tests and tension tests. A comparison between bending experiments and bending simulations is given. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
25.
26.
Dieter Weber Günther Burget Karl-Heinz Zirzow Hans Georg Von Schnering Alfred Schmidpeter 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract Alkalimetal diphenylphosphinites degrade (Ph-P)5 and P4 to give anions containing a chain of 2, 3 or 4 four- and two-coordinated phosphorus atoms. Representatives of the chain with two four-coordinated and one two-coordinated P atoms became first available from the aminolysis of tris (phosphoryl)phosphides1. 相似文献
27.
Karl-Heinz Jansen 《Mathematische Annalen》1969,183(3):185-200
Ohne Zusammenfassung 相似文献
28.
Joseph Foricher François Montavon Karl-Heinz Pfoertner Peter Schönholzer 《Helvetica chimica acta》1985,68(3):592-599
Synthesis and Reactions of 5-[p-(Dimethylamino)phenyl]-2,2-dimethyl-4-phenyl-3-oxazoline The title compound 8 has been synthesized in a one-pot reaction of 4′-(dimethylamino)benzoin ( 4 ) with 2-propanone and NH3. The preparation of the intermediate 4 from 3 is the first example of an acid-catalyzed transformation of the stable benzoin 3 into the corresponding less stable benzoin 4 . Structures and yields of various by-products occurring under different reaction conditions during the synthesis of 8 from 4 are given. The O-atom of the 3-oxazoline ring in 8 could be replaced by S from P2S5 yielding the 3-thiazoline 14 . Separation of the enantiomers of the racemate 8 could only be performed by transforming them into the trimethylanilinium salts 8b and 8c of (−)- and (+)-10-camphorsulfonic acid, respectively. Solid NaOAc in boiling toluene caused the precipitation of the 10-camphorsulfonic acids from the quaternary ammonium salts as sodium salts and the removing of the third methyl group from the quaternary ammonium salts as AcOMe to give the enantiomers (−)-(5S)- 8 and (+)-(5R)- 8 . Their absolute configurations are deduced from an X-ray analysis of 8b . 相似文献
29.
30.
Dr. Karl-Heinz Hoffmann 《Numerische Mathematik》1970,14(4):383-393
Summary In this paper we give some applications resulting from the theory of nonlinear approximation under side-conditions developed in a preceding paper [3]. Particularly a necessary condition for best approximation in terms of a generalized alternant is discussed, the approximating functions having restricted ranges. As special cases of this kind we deduce theorems for one-sided approximation and for approximations by positive functions. We conclude with a result in the theory of nonlinear programming.
Zweiter Teil einer gekürzten Fassung der Dissertation des Verfassers [3]. 相似文献
Zweiter Teil einer gekürzten Fassung der Dissertation des Verfassers [3]. 相似文献