全文获取类型
收费全文 | 1010篇 |
免费 | 21篇 |
国内免费 | 2篇 |
专业分类
化学 | 629篇 |
晶体学 | 27篇 |
力学 | 44篇 |
数学 | 165篇 |
物理学 | 168篇 |
出版年
2023年 | 6篇 |
2022年 | 15篇 |
2021年 | 11篇 |
2020年 | 27篇 |
2019年 | 21篇 |
2018年 | 31篇 |
2017年 | 30篇 |
2016年 | 53篇 |
2015年 | 33篇 |
2014年 | 40篇 |
2013年 | 135篇 |
2012年 | 64篇 |
2011年 | 97篇 |
2010年 | 76篇 |
2009年 | 48篇 |
2008年 | 59篇 |
2007年 | 53篇 |
2006年 | 43篇 |
2005年 | 30篇 |
2004年 | 24篇 |
2003年 | 19篇 |
2002年 | 31篇 |
2001年 | 17篇 |
2000年 | 9篇 |
1999年 | 3篇 |
1998年 | 9篇 |
1997年 | 9篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 4篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有1033条查询结果,搜索用时 0 毫秒
1.
2.
The centrosymmetric title compound, [Cd2{CH3OC6H4P(OC5H9)S2}4], features an eight‐membered [? Cd? S? P? S? ]2 ring owing to the presence of bridging dithiolate ligands. Tetrahedral coordination geometries for cadmium are completed by chelating ligands. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
3.
Hakki İsmail Erdoğan 《Journal of Geometry》1991,40(1-2):47-59
In this paper, the problem of determining the pencils of circles which form a hexagonal n-web in E2, is completely solved. It is well-known that n pencils of circles orthogonal to a fixed circle form a hexagonal n-web. Therefore, the main problem is the determination of all circle pencils which form a hexagonal n-web and which do not cut a fixed circle orthogonally. In this connection the following results have been obtained: The number of hexagonal 4-webs is six, whereas the number of hexagonal 5-webs is two.Finally, after having proved that the number of hexagonal 6-webs is one, it is shown that, for n7, there exist no circle pencils forming a hexagonal n-web without being orthogonal to a fixed circle. 相似文献
4.
A convenient procedure for the preparation of various substituted (thio)hydantoins is described. The method is based on Wittig and aza-Wittig reactions of parabanic acids with phosphonium ylides. The reactions occurred both regio- and stereo-selectively. 相似文献
5.
6.
Fiber-optic beam shaper based on multimode interference 总被引:1,自引:0,他引:1
A new method of fiber-optic based beam shaping is investigated both numerically and experimentally. A cylindrically symmetric method of lines (MoLs) is developed to simulate the device. The device is fabricated by fusion splicing a predetermined length of multimode fiber (MMF) to a single-mode fiber. The multimode interference (MMI) effects create ring-shaped field profiles at certain positions inside the MMF. The shaped beam can be used in medical applications requiring particular irradiation patterns. 相似文献
7.
8.
Tuba Gulsen Irena Jadlovsk Emrah Yilmaz 《Mathematical Methods in the Applied Sciences》2021,44(1):985-992
In this study, we consider parameter‐dependent diffusion eigenvalue problem on time scales. An upper bound on the number of eigenvalues for this problem on a finite time scale is given. 相似文献
9.
The aim of this study is to obtain further information about the source of proton relaxation in the Mn(II)-human serum albumin
complex. For this purpose, proton relaxation rates in albumin solutions 1/T
1 and 1/T
2 were measured versus increasing amounts of manganese [Mnt]. The fractions of manganese bound to albumin [Mnb] and free manganese [Mnf] were then determined from proton relaxation rate enhancement data. Paramagnetic contributions of bound manganese to the
observed relaxation rates (1/T
1p*)b and (1/T
2p*)b were also determined. Finally, the (1/T
2p*)b/(1/T
1p*)b ratio was used in a derived equation to estimate an effective correlation time τ. Mean τ value of the complex was found to be in the order of 3 ns, while the hydration number of bound manganese q was estimated to be about 4. The 1/τ was found to be the sum of the inverse values of rotational correlation time 1/τ
r, mean residence time of water in hydration spheres of the complex 1/τ
m, and longitudinal electronic relaxation time of manganese 1/τ
s in the complex. In conclusion, the relaxation mechanism in albumin solutions containing Mn(II) can be interpreted through
dipolar and scalar interactions modulated by τ
r, τ
m and τ
s. This analysis enables one to get reasonable figures for the τ
r and q of Mn(II) in albumin solution. 相似文献
10.
Validation and verification of social processes within agent-based computational organization models 总被引:1,自引:0,他引:1
Levent Yilmaz 《Computational & Mathematical Organization Theory》2006,12(4):283-312
The use of simulation modeling in computational analysis of organizations is becoming a prominent approach in social science
research. However, relying on simulations to gain intuition about social phenomena has significant implications. While simulations
may give rise to interesting macro-level phenomena, and sometimes even mimic empirical data, the underlying micro and macro
level processes may be far from realistic. Yet, this realism may be important to infer results that are relevant to existing
theories of social systems and to policy making. Therefore, it is important to assess not only predictive capability but also
explanation accuracy of formal models in terms of the degree of realism reflected by the embedded processes. This paper presents
a process-centric perspective for the validation and verification (V&V) of agent-based computational organization models.
Following an overview of the role of V&V within the life cycle of a simulation study, emergent issues in agent-based organization
model V&V are outlined. The notion of social contract that facilitates capturing micro level processes among agents is introduced
to enable reasoning about the integrity and consistency of agent-based organization designs. Social contracts are shown to
enable modular compositional verification of interaction dynamics among peer agents. Two types of consistency are introduced:
horizontal and vertical consistency. It is argued that such local consistency analysis is necessary, but insufficient to validate
emergent macro processes within multi-agent organizations. As such, new formal validation metrics are introduced to substantiate
the operational validity of emergent macro-level behavior.
Levent Yilmaz is Assistant Professor of Computer Science and Engineering in the College of Engineering at Auburn University and co-founder
of the Auburn Modeling and Simulation Laboratory of the M&SNet. Dr. Yilmaz received his Ph.D. and M.S. degrees from Virginia
Polytechnic Institute and State University (Virginia Tech). His research interests are on advancing the theory and methodology
of simulation modeling, agent-directed simulation (to explore dynamics of socio-technical systems, organizations, and human/team
behavior), and education in simulation modeling. Dr. Yilmaz is a member of ACM, IEEE Computer Society, Society for Computer
Simulation International, and Upsilon Pi Epsilon. URL: http://www.eng.auburn.edu/~yilmaz 相似文献