全文获取类型
收费全文 | 104篇 |
免费 | 0篇 |
专业分类
化学 | 52篇 |
晶体学 | 3篇 |
数学 | 1篇 |
物理学 | 48篇 |
出版年
2020年 | 1篇 |
2019年 | 1篇 |
2016年 | 1篇 |
2013年 | 8篇 |
2012年 | 3篇 |
2011年 | 13篇 |
2008年 | 4篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2004年 | 5篇 |
2003年 | 2篇 |
2002年 | 7篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 4篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1973年 | 5篇 |
1971年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有104条查询结果,搜索用时 15 毫秒
21.
Spoerke ED Bachand GD Liu J Sasaki D Bunker BC 《Langmuir : the ACS journal of surfaces and colloids》2008,24(14):7039-7043
Microtubules (MTs) are polar protein filaments that participate in critical biological functions ranging from motor protein direction to coordination of chromosome separation during cell division. The effective facilitation of these processes, however, requires careful regulation of the polar orientation and spatial organization of the assembled MTs. We describe here an artificial approach to polar MT assembly that enables us to create three-dimensional polar-oriented synthetic microtubule organizing centers (POSMOCs). Utilizing engineered MT polymerization in concert with functionalized micro- and nanoscale particles, we demonstrate the controllable polar assembly of MTs into asters and the variations in aster structure determined by the interactions between the MTs and the functionalized organizing particles. Inspired by the aster-like form of biological structures such as centrosomes, these POSMOCs represent a key step toward replicating biology's complex materials assembly machinery. 相似文献
22.
Bunker CE Novak KC Guliants EA Harruff BA Meziani MJ Lin Y Sun YP 《Langmuir : the ACS journal of surfaces and colloids》2007,23(20):10342-10347
The sonochemical reaction of iron pentacarbonyl is explored in water and in water with the protein BSA (bovine serum albumen). In water, the reaction is found to produce spherical nanoparticles of magnetite (Fe3O4) with a particle size distribution of <10 to approximately 60 nm. In water with BSA, the reaction produces either nanofibers or nanoneedles, depending on the concentration of BSA. The nanofiber and nanoneedle samples are found to be mixtures of goethite, lepidocrocite, and hematite (alpha-FeOOH, gamma-FeOOH, and alpha-Fe2O3, respectively). The sonochemical reaction of iron pentacarbonyl with BSA in water is thought to proceed through the thermal decomposition mechanism for iron pentacarbonyl with BSA acting as a templating agent. 相似文献
23.
A. Braithwaite S. Richardson L.N. Moyes F.R. Livens D.J. Bunker C.R. Hughes J.T. Smith J. Hilton 《Czechoslovak Journal of Physics》2000,50(2):265-269
Studies of uptake of radionuclides by natural materials have shown that sorption may occur via fast equilibrium exchange and/or slow kinetic processes, which can be described using a series of box models. This paper describes the use of such models to evaluate the solid-solution partitioning of 238U and 237Np on a clay rich sediment. Experimental data are obtained using the batch sorption technique, which are then analysed using 1, 2, and 3 box kinetic models. Uptake of 238U is initially rapid, with approximately 90% sorbed within the first 30 minutes. Sorption continues, but at a slower rate. Uptake of 237Np is initially slower than U, with approximately 30% sorbed within the first 30 minutes. Sorption again continues, at a slower rate. Analysis of the experimental data indicates that sorption can be described using 2 and 3 box kinetic models. The results demonstrate that sorption of uranium and neptunium on clay rich sediments occurs via equilibrium and kinetically controlled pathways, with neptunium being controlled by kinetics to a greater extent than uranium. The 2 or 3 box model can describe sorption of neptunium, uranium requires the 3 box model. 相似文献
24.
Structural transformations at the TiO2Pt and TiO2Ir interfaces during UV-irradiation have been probed by X-ray absorption spectroscopy. Oxidation by the photogenerated holes results in the intercalation of Pt and Ir into the Titania matrix. The structural transformations observed with Pt and Ir nanoparticles anchored on TiO2 is different than the clustering of gold atoms observed in the TiO2/Au system. Implications of such structural transformations on the photocatalytic activity of semiconductor photocatalyts are discussed. 相似文献
25.
A trajectory program was used to simulate the collisions of CH3NC with He, Xe, H2 and N2. Calculated energy transfer is in accord with experiment. The pattern of CH3NC vibrational mode energization is found to be noticeably non-random. The approximate sampling methods used in thermal unimolecular trajectory studies produce a more uniform state distribution. 相似文献
26.
The rotation-vibration Hamiltonian for an equilateral triangular X3 molecule is derived in terms of the three curvilinear stretching coordinates Δri, and expanded in the form of a power series in the variables yi = 1 ? exp(-aΔri), where a is a molecular parameter obtained from the potential function. The reason for the use of the variable yi is twofold: Stretching potentials exhibit a much stronger convergence in the yi than in the Δri, and a Hamiltonian expressed in the yi can be diagonalized in a straightforward fashion using a Morse-oscillator basis set as we do here. Using a published ab initio potential surface we have expanded it as a polynomial in the yi, and have calculated variationally the rotation-vibration energies of H3+ and D3+ using a symmetry-adapted Morse-oscillator-rigid symmetric top basis set. The results indicate that an expansion of the potential function to quartic terms in the yi might be adequate, and that satisfactorily converged energies can be obtained with a relatively small basis set. The molecule H3+ is the simplest polyatomic molecule. Inspection of the Appendix of this paper shows that the rotation-vibration Hamiltonian used here is one of the more complicated ones. 相似文献
27.
28.
Selenium (10–80 μg kg?1) is determined by hydride-generation atomic absorption spectrometry in mixed diet, faecal and urine samples and in standard reference materials (bovine liver, rice flour, wheat flour and horse kidney) after two digestion procedures. No difference was found in digestion efficiency between a nitric/sulphuric acid mixture and a nitric/sulphuric/perchloric acid mixture. The results suggest that the digestion of most biological materials for the determination of selenium does not require the use of perchloric acid. 相似文献
29.
We obtain exact cosmological solutions of a higher derivative theory described by the Lagrangian L=R+2αR
2 in the presence of interacting scalar field. The interacting scalar field potential required for a known evolution of the
FRW universe in the framework of the theory is obtained using a technique different from the usual approach to solve the Einstein
field equations. We follow here a technique to determine potential similar to that used by Ellis and Madsen in Einstein gravity.
Some new and interesting potentials are noted in the presence of R
2 term in the Einstein action for the known behaviours of the universe. These potentials in general do not obey the slow rollover
approximation. 相似文献
30.
Baldridge KK Donovan-Merkert BT O'Connor JM Lee LI Closson A Fandrick D Tran T Bunker KD Fouzi M Gantzel P 《Organic & biomolecular chemistry》2003,1(5):763-766
The metal-enediyne complexes [(eta 5-C5H5)Fe[eta 5-1,2-C5H3C identical to C(CH2)nC identical to]] (4, n = 4; 5, n = 5) and [(eta 5-C5H5)-Fe[eta 5-1,2-C5H3(C identical to C Me)2]] (6) were prepared from 1,2-diethynylferrocene (3). Complexes 4 and 5 were characterized in the solid state by X-ray crystallographic analysis. The structures of 4 and 6 were determined by computation using ab initio methods. A correlation was observed between ring-strain and increased ease of electrochemical oxidation along the series 6 (+0.164 V) to 5(+0.152 V) to 4 (+0.123 V). A similar trend in ionization potentials was identified in both the gas phase and in solution by computational methods. 相似文献