全文获取类型
收费全文 | 201篇 |
免费 | 12篇 |
国内免费 | 1篇 |
专业分类
化学 | 129篇 |
晶体学 | 8篇 |
力学 | 4篇 |
数学 | 34篇 |
物理学 | 39篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 8篇 |
2021年 | 12篇 |
2020年 | 10篇 |
2019年 | 12篇 |
2018年 | 5篇 |
2017年 | 7篇 |
2016年 | 15篇 |
2015年 | 6篇 |
2014年 | 9篇 |
2013年 | 11篇 |
2012年 | 17篇 |
2011年 | 12篇 |
2010年 | 8篇 |
2008年 | 14篇 |
2007年 | 12篇 |
2006年 | 5篇 |
2005年 | 8篇 |
2004年 | 6篇 |
2003年 | 1篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有214条查询结果,搜索用时 15 毫秒
61.
S. Kipp S. Kmmer R. Lacmann J. Rolfs U. Tanneberger W. Beckmann 《Crystal Research and Technology》1994,29(7):1005-1011
Crystal growth features on stearic acid, potassium nitrate, and potash alum have been determined by means of scanning force microscopy (SFM). Structures like growth spirals, etch pits, 2D-nuclei, and growth hillocks could be observed. The analysis of the face specific surface topographies leads to structures which correspond to those expected from kinetic measurements. 相似文献
62.
Dror Bar-Natan Stavros Garoufalidis Lev Rozansky Dylan P. Thurston 《Israel Journal of Mathematics》2000,119(1):217-237
We conjecture an exact formula for the Kontsevich integral of the unknot, and also conjecture a formula (also conjectured
independently by Deligne [De]) for the relation between the two natural products on the space of uni-trivalent diagrams. The
two formulas use the related notions of “Wheels” and “Wheeing”. We prove these formulas ‘on the level of Lie algebras’ using
standard techniques from the theory of Vassiliev invariants and the theory of Lie algebras. In a brief epilogue we report
on recent proofs of our full conjectures, by Kontsevich [Ko2] and by DBN, DPT, and T. Q. T. Le, [BLT].
This paper is available electronically 相似文献
63.
Resource allocation in the North Sea demersal fisheries: A goal programming approach 总被引:1,自引:0,他引:1
Simon Mardle Sean Pascoe Mehrdad Tamiz Dylan Jones 《Annals of Operations Research》2000,94(1-4):321-342
The management of a fishery is a complex task generally involving multiple, often conflicting, objectives. These objectives typically include economic, biological and social goals such as improving the income of fishers, reducing the catch of depleted species and maintaining employment.Multicriteria decision making (MCDM) techniques appear wellsuited to such a management problem, allowing compromises between conflicting objectives to be analysed in a structured framework. In comparison to other fields, such as water resource planning, forestry and agriculture, there have been few applications of MCDM to fisheries.In this paper, a goal programming model of the North Sea demersal fishery is presented. The model is used to demonstrate the potential applicability of this type of approach to the analysis and development of fisheries management plans with multiple objectives. Alternative scenarios are considered for the problem, and tradeoffs between given objectives are also highlighted and discussed. 相似文献
64.
Stephan Kipp Dr. Vladimir Šepelák Dr. habil. Klaus Dieter Becker Prof. Dr. 《Chemie in Unserer Zeit》2005,39(6):384-392
Mechanochemistry offers a wide spectrum of possible applications. The standard preparation methods of solid state chemistry often require high temperatures or pressures, well defined gas atmospheres or special reactants' conditions. In the mechanochemical process not more than an adequately powerful ball mill with accessories is required. With this method, a lot of chemical reactions can be carried out via a non-thermal, sustainable reaction pathway. 相似文献
65.
66.
Dr Andrew Dolan Dylan A. Sherman Prof. Rob Atkin Prof. Gregory G. Warr 《Chemphyschem》2016,17(19):3096-3101
The Kamlet–Taft solvent parameters of solvate ionic liquids (SILs) prepared from lithium salts with glyme and glycol ligands are determined. The dipolarity/polarisibilities (π*) are high, similar to those found in conventional ionic liquids. The H‐bond basicities (β) depend strongly on the anion. The H‐bond acidities (α) are high in both glyme and glycol SILs, indicating that the lithium is acting as a H‐bond donor site. “Poor” SILs have glyme‐rich and salt‐rich regions. In these liquids the π* and β values are almost identical to the parent glyme or glycol, and the α values are determined by the salt alone. 相似文献
67.
Silvia C. Capelli Hans‐Beat Bürgi Sax A. Mason Dylan Jayatilaka 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(10):949-952
Neutron diffraction data have been collected at 12, 50, 150 and 295 K for the dipeptide glycyl‐L‐alanine, C5H10N2O3, in order to obtain accurate positional and anisotropic displacement parameters for the H atoms. The values of these parameters serve as a benchmark for assessing the equivalent parameters obtained from a so‐called Hirshfeld‐atom refinement of X‐ray diffraction data described elsewhere [Capelli et al. (2014). IUCrJ, 1 , 361–379]. The flexibility of the glycyl‐L‐alanine molecule in the solid and the hydrogen‐bonding interactions as a function of temperature are also considered. 相似文献
68.
Ying-Li Rao Dylan Schoenmakers Yi-Lu Chang Jia-Sheng Lu Prof. Zheng-Hong Lu Prof. Youngjin Kang Prof. Suning Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(36):11306-11316
New phosphorescent PtII compounds based on dimesitylboron (BMes2)-functionalized 2-phenylpyridyl (ppy) N,C-chelate ligands and an acetylacetonato ancillary ligand have been achieved. We have found that BMes2 substitution at the 4′-position of the phenyl ring can blue-shift the phosphorescent emission energy of the PtII compound by approximately 50 nm, compared to the 5′-BMes2 substituted analogue, without substantial loss of luminescent quantum efficiencies. The emission color of the 4′-BMes2 substituted PtII compound, Pt(Bppy)(acac) ( 1 ) can be further tuned by the introduction of a substituent group at the 3′-position of the phenyl ring. A methyl substituent red-shifts the emission energy of 1 by approximately 10 nm whereas a fluoro substituent blue-shifts the emission energy by about 6 nm. Using this strategy, three bright blue-green phosphorescent PtII compounds 1 , 2 and 3 with emission energy at 481, 492, and 475 nm and ΦPL=0.43, 0.26 and 0.25, respectively, have been achieved. In addition, we have examined the impact of BMes2 substitution on 3,5-dipyridylbenzene (dpb) N,C,N-chelate PtII compounds by synthesizing compound 4 , Pt(Bdpb)Cl, which has a BMes2 group at the 4′-position of the benzene ring. Compound 4 has a phosphorescent emission band at 485 nm and ΦPL=0.70. Highly efficient blue-green electroluminescent (EL) devices with a double-layer structure and compounds 1 , 3 or 4 as the phosphorescent dopant have been fabricated. At 100 cd m−2 luminance, EL devices based on 1 , 3 and 4 with an external quantum efficiency of 4.7, 6.5 and 13.4 %, respectively, have been achieved. 相似文献
69.
Design of bicontinuous donor/acceptor morphologies for use as organic solar cell active layers
下载免费PDF全文
![点击此处可从《Journal of Polymer Science.Polymer Physics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dylan Kipp Rafael Verduzco Venkat Ganesan 《Journal of Polymer Science.Polymer Physics》2016,54(9):884-895
In recent works, we demonstrated the achievement of bicontinuous donor/acceptor morphologies by the addition of conjugated block copolymers to a blend of conjugated homopolymer donors and fullerene acceptors. However, the domain sizes resulting in experiments were much larger than those of interest for high‐performance organic solar cells. Moreover, a significant concentration of fullerene acceptors was present in the donor domains. Here, we utilize simulations to study the bicontinuous donor/acceptor morphologies that result for different parametric conditions. Using such results, we provide guidelines for how to blend polymer materials to give rise to bicontinuous phases with the smaller and more compositionally pure domains that are desirable for organic photovoltaic applications. Our results can be generalized to treat a large range of donor and acceptor monomers. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 884–895 相似文献
70.
Dylan Dagoneau Amandine Kolleth Pierre Quinodoz Gamze Tanriver Saron Catak Alexandre Lumbroso Sarah Sulzer-Mossé Alain De Mesmaeker 《Helvetica chimica acta》2020,103(1):e1900217
Herein, we describe a high yielding approach towards the synthesis of 3-amino-indoles and -benzofurans through 6π-electrocyclization. This was made possible by taking advantage of the high reactivity of keteniminium salts, formed in-situ by treating with triflic anhydride and 2-fluoropyridine amides bearing at the α-position either an aniline or a phenoxy moiety. These mild conditions, on top of furnishing rapidly the 3-aminobenzoheteroles, allow the tolerance of various functional groups. Control experiments were carried out to highlight that the keteniminium is, indeed, in most cases, the reactive intermediate and conformational preferences of such species were investigated through a DFT study. 相似文献