全文获取类型
收费全文 | 151篇 |
免费 | 7篇 |
国内免费 | 3篇 |
专业分类
化学 | 99篇 |
晶体学 | 3篇 |
力学 | 3篇 |
数学 | 36篇 |
物理学 | 20篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 7篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 13篇 |
2012年 | 14篇 |
2011年 | 19篇 |
2010年 | 11篇 |
2009年 | 9篇 |
2008年 | 4篇 |
2007年 | 11篇 |
2006年 | 4篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 7篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
排序方式: 共有161条查询结果,搜索用时 15 毫秒
81.
Uğur Tamer İsmail H. Boyacı Erhan Temur Adem Zengin İlker Dincer Yalçın Elerman 《Journal of nanoparticle research》2011,13(8):3167-3176
The preparation and application of rod-shaped core–shell structured Fe3O4–Au nanoparticles for immunomagnetic separation and sensing were described for the first time with this study. To synthesize
magnetic gold nanorod particles, the seed-mediated synthetic method was carried out and the resulting nanoparticles were characterized
with transmission electron microscopy (TEM), ultraviolet visible spectroscopy (UV–Vis), energy-dispersive X-ray (EDX), and
X-ray diffraction (XRD). Magnetic properties of the nanoparticles were also examined. Characterization of the magnetic gold
nanorod particles has proven that the resulting nanoparticles were composed of Fe3O4 core and the gold shell. The rod-shaped gold-coated iron nanoparticles have an average diameter of 16 ± 2 nm and an average
length of about 50 ± 5 nm (corresponding aspect ratio of 3). The saturation magnetization value for the magnetic gold nanorod
particles was found to be 37 emu/g at 300 K. Rapid and room temperature reaction synthesis of magnetic gold nanorod particles
and subsequent surface modification with E. coli antibodies provide immunomagnetic separation and SERS application. The analytical performance of the SERS-based homogenous
sandwich immunoassay system with respect to linear range, detection limit, and response time is also presented. 相似文献
82.
83.
Comparative study of electrical properties of Au/n-Si (MS) and Au/Si3N4/n-Si (MIS) Schottky diodes 下载免费PDF全文
In this paper, the electrical parameters of Au/n-Si (MS) and Au/Si3N4/n-Si (MIS) Schottky diodes are obtained from the forward bias current-voltage (I-V) and capacitance-voltage (C-V) measurements at room temperature. Experimental results show that the rectifying ratios of MS and MIS diode at ± 5 V are found to be 1.25×103 and 1.27×104, respectively. The main electrical parameters of MS and MIS diode, such as the zero-bias barrier height (Φ Bo) and ideality factor (n) are calculated to be 0.51 eV (I-V), 0.53 eV (C-V), and 4.43, and 0.65 eV (I-V), 0.70 eV (C-V), and 3.44, respectively. Also, the energy density distribution profile of the interface states (Nss) is obtained from the forward bias I-V. In addition, the values of series resistance (Rs) for the two diodes are calculated from Cheung's method and Ohm's law. 相似文献
84.
Alejandro Adem Jianzhong Pan 《Transactions of the American Mathematical Society》2006,358(9):3969-3983
In this paper we compute the integral cohomology of certain semi-direct products of the form , arising from a linear action on the -torus, where is a finite group. The main application is the complete calculation of torsion gerbes for six-dimensional examples arising in string theory.
85.
We use equivariant methods to define and study the orbifold K-theory of an orbifold X. Adapting techniques from equivariant K-theory, we construct a Chern character and exhibit a multiplicative decomposition
for K
*
orb
(X)⊗ℚ, in particular showing that it is additively isomorphic to the orbifold cohomology of X. A number of examples are provided. We then use the theory of projective representations to define the notion of twisted
orbifold K–theory in the presence of discrete torsion. An explicit expression for this is obtained in the case of a global
quotient.
Received: 21 August 2001 / Accepted: 27 January 2003
Published online: 13 May 2003
RID="*"
ID="*" Both authors were partially supported by the NSF
RID="*"
ID="*" Both authors were partially supported by the NSF
Communicated by R.H. Dijkgraaf 相似文献
86.
Abdullah KEPCEOLU Yasemin GÜNDODU Adem SARILMAZ Mustafa ERS
Z Faruk
ZEL Hamdi ükür KILI 《Turkish Journal of Chemistry》2021,45(2):485
In this study, rhenium/rhenium oxide nanoparticles (Re / ReO3 NPs) have been produced for the first time in ultrapure water by using Femtosecond Pulsed Laser Ablation in Liquid (fsPLAL) method. X-Ray Diffraction (XRD) measurements and results obtained for NPs show the existence of well-crystallized peaks and preferred phases. Re NPs have hexagonal structure while ReO3 NPs have the perovskite-like cubic crystal structures. The Re / ReO3 ratio is also determined to be 53 / 47 with ~ 20 nm crystallite size, while pure ReO3 crystallite sizes were measured to be ~ 25 nm. The TEM results have shown that the produced particles have a spherical shape, and particle sizes changes between ~ 20 nm and ~ 60 nm. The crystallite size is similar due to XRD results. Obtained nanoparticles exhibit promising applications for photonic devices with broad bandgap values which have measured to be 4.71 eV for Re / ReO3 NPs mixture and 4.36 eV for pure ReO3 NPs. 相似文献
87.
Coles SJ Davies DB Eaton RJ Hursthouse MB Kiliç A Shaw RA Uslu A 《Dalton transactions (Cambridge, England : 2003)》2007,(20):2040-2047
Derivatives of the tri-spirane pentaerythritoxy-cyclophosphazene compound, 1, have been used to investigate the stereogenic properties of spiranes combined with four equivalent conventional centres of chirality. In compound 1 the two inner rings are carbocyclic and symmetrical and the two outer rings are cyclotriphosphazenes substituted in different positions to provide the conventional centres of chirality. The case of combining spiranes with four equivalent centres of chirality has been investigated by the reaction of 1 with dimethylamine in a 1 : 8 molar ratio to give four diastereoisomeric products, in which the two cyclophosphazene rings are non-geminally di-substituted in either cis or trans configurations; viz. the cis-cis (2a), cis-trans (2b) and two trans-trans substituted dimethylamine derivatives 2c and 2d. The structure and stereogenic properties of compound 2a (C2 symmetry) have been characterized previously by both X-ray crystallography and 31P NMR spectroscopy on addition of a chiral solvating agent (CSA) and the structures and stereogenic properties of compounds 2b (C1) and 2d (C2) have been similarly characterized in this work. The structure of compound 2c has been characterised by X-ray crystallography and found to be meso with the relatively rare S4 symmetry. The four diastereoisomeric products 2a-2d represent all the possible stereochemical isomers of a spirane combined with four equivalent conventional centres of chirality. 相似文献
88.
1,3-Disubstituted-2,3-dihydro-1H-naphth[1,2-e][1,3]oxazines were prepared through the ring-closure reactions of the aminobenzylnaphthols with substituted aryl- and heteroarylaldehydes. 相似文献
89.
Allylic onium salts with different hetero‐atoms and various substituent groups at the allylic double bond have been shown to be very efficient initiators for cationic polymerization. When attacked by a radical, they become radical cations, which are highly unstable species, and undergo fragmentation into smaller radical cations called onium radical cations. The reaction mechanism involves radical formation, addition and fragmentation. In our previous work, radical initiators generated in the same way and under the same conditions are studied experimentally for their ability to affect the polymerization efficiency. Here, the factors affecting the polymerization efficiency are discussed theoretically using semi‐empirical quantum mechanical techniques. The type of radical species, substituent group at the allylic side, the heteroatom at the onium side and the onium group itself are analyzed separately. For this purpose, the geometries of different onium radical cations to be fragmented are optimized and the strength of the C–heteroatom bond to be broken and the size of the radical cations after fragmentation are considered. 相似文献
90.