全文获取类型
收费全文 | 569篇 |
免费 | 10篇 |
专业分类
化学 | 359篇 |
晶体学 | 2篇 |
力学 | 16篇 |
数学 | 126篇 |
物理学 | 76篇 |
出版年
2018年 | 6篇 |
2016年 | 7篇 |
2014年 | 5篇 |
2013年 | 12篇 |
2012年 | 17篇 |
2011年 | 19篇 |
2010年 | 6篇 |
2008年 | 11篇 |
2007年 | 14篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 7篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1984年 | 7篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 10篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1976年 | 13篇 |
1975年 | 5篇 |
1961年 | 5篇 |
1943年 | 8篇 |
1942年 | 7篇 |
1941年 | 5篇 |
1940年 | 6篇 |
1937年 | 5篇 |
1936年 | 5篇 |
1934年 | 7篇 |
1933年 | 5篇 |
1931年 | 8篇 |
1929年 | 10篇 |
1926年 | 7篇 |
1925年 | 6篇 |
1924年 | 7篇 |
1923年 | 6篇 |
1914年 | 6篇 |
1913年 | 6篇 |
1912年 | 6篇 |
1911年 | 7篇 |
1910年 | 5篇 |
1909年 | 8篇 |
1907年 | 7篇 |
1891年 | 7篇 |
1890年 | 7篇 |
1887年 | 5篇 |
1869年 | 5篇 |
排序方式: 共有579条查询结果,搜索用时 15 毫秒
101.
102.
P.J. Gustav Meyer 《Discrete Mathematics》1974,9(2):119-146
It is shown how all orthomodular posets (of various kinds) are constructible from families of sets satisfying various conditions, usually with the generating family emerging as identical with (or contained in) the family of frames (that is, maximal orthogonal subsets of the non-zero elements) of the constructed orthomodular poset. 相似文献
103.
Ohne ZusammenfassungDerIII. Teil des Berichts über den 4. Internationalen Kongre\ für Rheologie 1963, der über etwa 35 weitere Vorträge berichtet, folgt in einem der nächsten Hefte. Hinsichtlich derbiorheologischen Beiträge sei auf den Tagungsbericht vonH. H. Pfeiffer-Bremen in Kolloid-Z. u. Z. Polymere195, H. 1, 53–57 (1964) und auf die Zeitschrift Biorheology verwiesen. Aus diesem Grunde wird darüber hier nicht nochmals gesondert berichtet. 相似文献
104.
Ivo Lang Viktor Dobal Gustav Šebor 《Spectrochimica Acta Part B: Atomic Spectroscopy》1982,37(4):309-317
An equilibrium model for a wet acetylene flame has been used for the calculation of the distribution of carbon, aluminium and silicon between gaseous and condensed phases. Calculated values of free atom vapour fractions are in agreement with published experimental data. It is thermodynamically probable that the formation of condensed phases limits atom vapour formation. There is a relationship between the position of an element in the Periodic Table and the nature of the condensed phase. 相似文献
105.
Michael Klasen Gustav Kramer 《The European Physical Journal C - Particles and Fields》2010,70(1-2):91-106
Now that new publications of H1 data for the diffractive photoproduction of dijets, which overlap with the earlier published H1 data and the recently published data of the ZEUS collaboration, have appeared, we have recalculated the cross sections for this process in next-to-leading order (NLO) of perturbative QCD to see whether they can be interpreted consistently. The results of these calculations are compared to the data of both collaborations. We find that the NLO cross sections disagree with the data, showing that factorization breaking occurs at that order. If direct and resolved contributions are both suppressed by the same amount, the global suppression factor depends on the transverse-energy cut. However, by suppressing only the resolved contribution, also reasonably good agreement with all the data is found with a suppression factor independent of the transverse-energy cut. 相似文献
106.
Jonathan P. Caulkins Gustav Feichtinger Richard F. Hartl Peter M. Kort Andreas J. Novak Andrea Seidl 《Central European Journal of Operations Research》2013,21(3):507-522
Becker and Murphy (J Polit Econ 96(4):675–700, 1988) have established the existence of unstable steady states leading to threshold behavior for optimal consumption rates in intertemporal rational addiction models. In the present paper a simple linear-quadratic optimal control model is used to illustrate how their approach fits into the framework of multiple equilibria and indifference-threshold points. By changing the degree of addiction and the level of harmfulness we obtain a variety of behavioral patterns. In particular we show that when the good is harmful as well as very addictive, an indifference-threshold point, also known in the literature as a Skiba point, separates patterns converging to either zero or maximal consumption, where the latter occurs in the case of a high level of past consumption. This implicitly shows that an individual needs to be aware in time of these characteristics of the good. Otherwise, he/she may start consuming so much that in the end he/she is totally addicted. 相似文献
107.
Gustav Christ und Co. 《Fresenius' Journal of Analytical Chemistry》1905,44(6-7):412
Ohne Zusammenfassung 相似文献
108.
Density functional theory calculations for the hydrogen evolution reaction in an electrochemical double layer on the Pt(111) electrode 总被引:1,自引:0,他引:1
Skúlason E Karlberg GS Rossmeisl J Bligaard T Greeley J Jónsson H Nørskov JK 《Physical chemistry chemical physics : PCCP》2007,9(25):3241-3250
We present results of density functional theory calculations on a Pt(111) slab with a bilayer of water, solvated protons in the water layer, and excess electrons in the metal surface. In this way we model the electrochemical double layer at a platinum electrode. By varying the number of protons/electrons in the double layer we investigate the system as a function of the electrode potential. We study the elementary processes involved in the hydrogen evolution reaction, 2(H(+) + e(-)) --> H(2), and determine the activation energy and predominant reaction mechanism as a function of electrode potential. We confirm by explicit calculations the notion that the variation of the activation barrier with potential can be viewed as a manifestation of the Br?nsted-Evans-Polanyi-type relationship between activation energy and reaction energy found throughout surface chemistry. 相似文献
109.
Volker?Rudolf?Gustav?LammersEmail author Angelika?Morant Judith?Wemmer Erich?Josef?Windhab 《Rheologica Acta》2017,56(10):841-850
The aeration of emulsions with tailored properties and structure is of widespread importance in processing of foods and cosmetics. This report addresses the micro-cellular foam formation of carbon dioxide-saturated oil-in-water emulsions triggered by the application of a controlled pressure drop. The experimental setup combines a stirred pressure vessel with a pressure cell-equipped rheometer and pneumatic expansion valves. This allows to systematically study the process of gas dissolution, bubble nucleation, and growth under defined pressure, temperature, and flow conditions. Investigations on the impact of relevant process parameters show that dissolved gas fraction, emulsion viscosity, and shear rate have a major influence on foam formation. Dissolution of carbon dioxide leads to a viscosity reduction of the emulsion which and is described by a viscosity reduction factor. The point of bubble nucleation is derived from rheological patterns during depressurization. Experiments show that lower emulsion viscosity and higher shear rate favor bubble nucleation upon pressure release. Rheological results are supported by video analysis as the setup allows capturing nucleation, growth, and destabilization of bubbles as a function of pressure, supersaturation, and time. The results of this work yield the understanding of the high-pressure foaming mechanism from a rheological perspective and foster the design of such processes. 相似文献
110.
The influence of weak convection, caused by surface tension forces, on radial dopant segregation occurring in crystals grown under microgravity conditions is studied numerically. The geometry considered corresponds to a floating-zone configuration with partially coated melt surfaces consisting of small evenly distributed spots of free surfaces. In order to distinguish dopant distribution due to weak convection clearly from distribution due to diffusion the spots only cover one quarter of the periphery. Thus, surface tension-driven convection is allowed only over one quarter of the floating-zone configuration resulting in an asymmetric dopant distribution. The percentage of free surfaces present is varied in order to alter the Marangoni flow rates. The maximum dopant concentration due to radial segregation is plotted as a function of a certain convection level. The results of the present numerical study are supposed to be used to design corresponding space experiments launched at the end of the year 2000. 相似文献