全文获取类型
收费全文 | 83篇 |
免费 | 1篇 |
国内免费 | 5篇 |
专业分类
化学 | 47篇 |
力学 | 3篇 |
数学 | 6篇 |
物理学 | 33篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 1篇 |
2014年 | 4篇 |
2013年 | 5篇 |
2012年 | 2篇 |
2011年 | 4篇 |
2009年 | 2篇 |
2008年 | 5篇 |
2007年 | 6篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2004年 | 7篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有89条查询结果,搜索用时 15 毫秒
1.
In this paper we study small and large solid-core PCFs with elliptical shaped air-holes for the hexagonal lattice, which were constructed by omitting one air-hole (small core) and seven air-holes (large core), respectively, and we compare their characteristics with those with circular holes. We use two types of ellipticity: vertical and horizontal. Birefringence, dispersion, and the numerical apertures of the fundamental modes are analyzed using commercial simulation software. Also, the confinement loss is obtained. The effect of ellipticity on these characteristics is investigated in detail. It is found that the type of ellipticity of the air holes affects the numerical aperture and hence confinement loss significantly, but it has no crucial effect on either the dispersion or the birefringence for the small and large core PCFs. 相似文献
2.
A Raney-Ag catalyst was prepared by leaching out aluminium from a Raney Ag-Al alloy with NaOH solution. The kinetics of leaching
has been investigated in a stirred-batch-reactor at various temperatures by using alloy particles of different sizes. The
kinetic model best fitting the experimental results has been determined.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
3.
CAO Ling-di FANG Yan FANG Chun-hui . Key Laboratory of Salt Resources Chemistry 《高等学校化学研究》2011,(3):490-495
Detailed time-and-space-averaged structure of MgSO4 in the concentrated aqueous solutions was investigated via X-ray diffraction with an X’pert Pro θ-θ diffractometer at 298 K, yielding structural function and radial distribution function(RDF). The developed KURVLR program was employed for the theoretical investigation in consideration of the ionic hydration and ion association. Multi-peaks Gaussian fitting method was applied to deconvolving the overlapping bands of Differential radial distribution function... 相似文献
4.
5.
A new copper(II) complex, [Cu(Bphen)(Leu)(NO3)(H2O)] (Bphen = 4,7-diphenyl-1,10-phenanthroline, leu = L-leucine), has been synthesized and characterized by IR spectroscopy, CHN analysis, and single-crystal X-ray diffraction techniques. The CT-DNA binding properties of the complex have been investigated by both absorption and emission spectroscopy. The binding parameters for the fluorescence Scatchard plot were also determined. Further, the interaction of the complex with bovine serum albumin (BSA) has been investigated using absorption and emission spectroscopy. The thermodynamic parameters, free energy change (ΔG), enthalpy change (ΔH), and entropy change (ΔS), were calculated by the van’t Hoff equation and discussed. The distance between BSA and the complex has been obtained according to fluorescence resonance energy transfer. Conformational changes of BSA have been observed from synchronous fluorescence. Antioxidant and radical scavenging activities of the complex were determined by various in vitro assays such as 1,1-diphenyl-2-picryl-hydrazyl free radicals (DPPH˙), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) radicals (ABTS˙+), and reducing ability determination by H2O2 scavenging methods. 相似文献
6.
H. Inci 《Journal of Differential Equations》2018,264(4):2660-2683
In this paper we consider the inviscid SQG equation on the Sobolev spaces , . Using a geometric approach we show that for any the corresponding solution map, , is nowhere locally uniformly continuous. 相似文献
7.
Griffiths DV Al-Jeboori MJ Cheong YK Duncanson P Harris JE Salt MC Taylor HV 《Organic & biomolecular chemistry》2008,6(3):577-585
Dialkyl heteroaroylphosphonates based on thiophene, pyrrole or furan have been prepared and their reactions with trimethyl phosphite investigated. Deoxygenation of the carbonyl groups in these heteroaroylphosphonates occurs to give carbene intermediates, which then undergo further reaction. In the case of the furan-3-oylphosphonates and those systems containing a thiophene or pyrrole ring, the major reaction pathway involves intermolecular trapping of the carbene intermediates by the trimethyl phosphite, leading to the formation of ylidic phosphonates that can be readily converted into the corresponding 1,1-bisphosphonates. However, in some furan-2-oylphosphonates the carbenes generated undergo ring-opening to initially give acyclic alkynylphosphonates which may react further to give other novel phosphorus compounds. The effects of substituents on the extent to which intermolecular trapping of the initially formed carbene competes with intramolecular rearrangement has been investigated. The latter process appears to be suppressed by a substituent at the 5-position of the furan ring, the resulting ylidic phosphonates being a rare example of an efficient intermolecular trapping of a furan-2-yl carbene. 相似文献
8.
Hasan Inci 《Journal of Nonlinear Mathematical Physics》2016,23(2):213-233
In this paper we consider the Holm-Staley b-family of equations in the Sobolev spaces Hs(?) for s>3/2. Using a geometric approach we show that, for any value of the parameter b, the corresponding solution map,u(0)?u(T ), is nowhere locally uniformly continuous. 相似文献
9.
Märki I Salt M Herzig HP Stanley R El Melhaoui L Lyan P Fedeli JM 《Optics letters》2006,31(4):513-515
We present all-optical tuning and switching of a microcavity inside a two-dimensional photonic crystal waveguide. The photonic crystal structure is fabricated in silicon-on-insulator using complementary metal-oxide semiconductor processing techniques based on deep ultraviolet lithography and is completely buried in a silicon dioxide cladding that provides protection from the environment. By focusing a laser onto the microcavity region, both a thermal and a plasma dispersion effect are generated, allowing tuning and fast modulation of the in-plane transmission. By means of the temporal characteristics of the in-plane transmission, we experimentally identify a slower thermal and a fast plasma dispersion effect with modulation bandwidths of the order of several 100 kHz and up to the gigahertz level, respectively. 相似文献
10.
Study on phase diagrams and properties of solutions in ternary systems Li+,K+(Mg2+)/SO42--H2O at 25℃
LI Bing LI Jun FANG Chun-Hui WANG Qing-Zhong SONG Peng-ShengQinghai Institute of Salt Lakes Chinese Academy of Sciences Xining Qinghai China 《中国化学》1995,(2)
Solubilities of ternary systems Li+,K+/SO42--H2O (1) and Li+,Mg2+/SO42-H2O (2) were investigated by isothermal method at 25℃. Physico-chemical properties of solutions, such as density, refractive index, viscosity, conductivity and pH, were determined. Phase diagram of the system (1) consists of three solubility branches and three crystallization fields corresponding to K2SO4, Li2SO4.H2O and LiKSO4. LiKSO4 is an incongruent compound, and its transition point is estimated graphically to be 45.5-46.0℃. No solid solution of LiKSO4 with Li2SO4.H2O was found in the system. The system (2) is a simple eutonic type. Pitzer model of electrolyte solution was used to check the obtained solubilities. Data comparison gives good agreement. Two equations were used to correlate density, refractive index of the solution with its composition. Differences between measured and calculated values are less than 0.6% for density, 0.15% for the latter. 相似文献