全文获取类型
收费全文 | 120篇 |
免费 | 4篇 |
专业分类
化学 | 54篇 |
晶体学 | 8篇 |
力学 | 17篇 |
数学 | 23篇 |
物理学 | 22篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 1篇 |
2019年 | 5篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 8篇 |
2012年 | 7篇 |
2011年 | 5篇 |
2010年 | 5篇 |
2009年 | 6篇 |
2008年 | 6篇 |
2007年 | 7篇 |
2006年 | 6篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1991年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有124条查询结果,搜索用时 15 毫秒
111.
112.
The 16 × 16 spinor equations of two fermions interacting with their charges and anomalous magnetic moments have been separated first covariantly into center of mass and relative coordinates, then completely into angular and radial parts. The 16 radial equations reduce by a symmetry into two sets of 8 equations, four of which are algebraic. The final result is a set of four first order equations or two coupled second order equations. 相似文献
113.
In Couette flows over undulated substrates eddies can be generated under creeping flow conditions. In contrast to free surface flows on undulated substrates even smooth bottom undulations allow for eddy generation due to the kinematical constraints. The subject of our paper is how these flow patterns interact with the temperature field in non–isothermal flows. Our analysis of the thermo–mechanical coupling is focused on the two dominant effects, namely convection and thermoviscosity, whereas dissipation heat, buoyancy and temperature–dependence of the remaining material parameters are neglected. We solve the problem in two steps: First, the influence of the eddies on the convective heat transfer is considered by solving the heat conduction equation with convection. For the velocity field we take the solution resulting analytically from Reynolds' lubrication approximation for the isothermal flow. The thermoviscous feedback of the resulting temperature field to the flow is considered in forthcoming papers. For the construction of the solution an analytical approach based on a nonorthogonal series representation of the fundamental fields and a variational formulation of the field equations is used. The results are visualised and the physical effects they reveal are discussed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
114.
Mehmet Somer Mehmet Nuri Kütükcü Raul Cardoso Gil Horst Borrmann Wilder Carrillo‐Cabrera 《无机化学与普通化学杂志》2004,630(7):1015-1021
The title compounds have been synthesized at 1473 K from stoichiometric mixtures of the binary components Mg3N2, MgX2 (X = Cl, I) and BN in arc‐welded steel ampoules encapsulated in evacuated silica tubes. Mg2[BN2]Cl ( 1 ) and Mg8[BN2]5I ( 2 ) crystallize in the orthorhombic space groups Pbca (no. 61) and Imma (no. 74), respectively, with a = 6.6139(8)Å, b = 9.766(1)Å, c = 10.600(1)Å, Z = 8 for 1 and a = 13.535(3)Å, b = 9.350(2)Å, c = 11.194(2)Å, Z = 4 for 2 . The crystal structures are characterized mainly by Mg6 trigonal prisms which are condensed to 3D frameworks in different ways. Part of the trigonal prisms are centered by the [N—B—N]3— anions and other voids in the framework by the X— anions. The magnesium environment around Cl— is a very distorted monocapped trigonal prism (CN = 6+1) and that of I— is a bicapped heptagonal prism (CN = 14+2). The bond lengths and bond angles for the relevant [BN2]3— anions are d(B—N) = 1.330 — 1.338Å, ∠N—B—N = 175.8° in 1 and d(B—N) = 1.330 — 1.339Å, ∠N—B—N = 176.8° — 178.0° in 2 . The vibrational spectra of the title compounds have been recorded and interpreted based on the D∞h symmetry of the relevant [N—B—N]3— groups considering the site symmetry splitting. 相似文献
115.
Ahmed Nuri Kursunlu Ersin Guler Hakan Dumrul Ozcan Kocyigit Ilkay Hilal Gubbuk 《Applied Surface Science》2009,255(21):8798-8803
In this study, three Schiff base ligands and their complexes were synthesized and characterized by infrared spectroscopy (IR), thermogravimetric analyses (TGA), nuclear magnetic resonance (NMR), elemental analysis and magnetic susceptibility apparatuses. Silica gel was respectively modified with Schiff base derivatives, (E)-2-[(2-chloroethylimino)methyl]phenol, (E)-4-[(2-chloroethylimino)methyl]phenol and N,N′-[1,4-phenilendi(E)methylidene]bis(2-chloroethanamine), after silanization of silica gel by (3-aminopropyl)trimethoxysilane (APTS) by using a suitable method. Characterization of the surface modification was also performed with IR, TGA and elemental analysis. The immobilized surfaces were used for Co(II) and Ni(II) sorption from aqueous solutions and values of sorption were detected by atomic absorption spectrometer (AAS). 相似文献
116.
Svetoslav Marinov Matthias Kern Nikolaos Zarzalis Peter Habisreuther Antonio Peschiulli Fabio Turrini O. Nuri Sara 《Flow, Turbulence and Combustion》2012,89(1):73-95
One of the most promising methods for reducing NO x emissions of jet engines is the lean combustion process. For realization of this concept the percentage of air flowing through the combustor dome has to be drastically increased, which implies high volume fluxes in the primary zone of the combustion chamber and represents a substantial challenge in regard to the flame stabilization. Swirl motion is thus applied to the air flux by the swirl generator and decisively contributes to the flame stabilization. The current paper reviews an atmospheric investigation of a burner configuration in regard to the weak extinction limit, comprising a confined non-premixed swirl-stabilized flame. The burner can be supplied with either kerosene or after a small adaption with natural gas (methane). Therefore, a comparison of a kerosene-fuelled flame (spray flame) to a natural gas fuelled one (methane flame) can be performed. Both are realized by almost identical burner configuration and at identical conditions. The main idea of this work is to align the stability characteristics of both flames by means of similarity. However, fundamental differences regarding the flame structures of the flames are detected through in-flame measurements. This determines the limits of the current approach and motivates an appropriate choice of flame modeling. 相似文献
117.
Hüseyin Ünver Mustafa Yıldız Nazan Ocak Tahsin Nuri Durlu 《Journal of chemical crystallography》2008,38(2):103-108
Abstract Schiff base 3-[(2-morpholinoethylimino)methyl]benzene-1,2-diol has been synthesized from the reaction of 4-(2-aminoethyl)morpholine
with 2,3-dihydroxybenzaldehyde. The title compound has been characterized by elemental analysis, IR, 1H-NMR, 13C-NMR and UV–visible techniques. The structure of the compound also has been examined crystallographically. For the compound
exist as dominant form of enol-imines in both the solutions and solid state. The crystal structure has been solved by direct
methods and refined by full-matrix least squares. The title compound crystallize in the monoclinic space group P21/n with a = 12.085(1), b = 8.256(1), c = 13.650(1) ?, β = 108.56(1)°, V = 1291.1(2) ?3, D
x
= 1.288 g cm−3, respectively (R
1 = 0.0336 and wR
2 = 0.0922 for 2117 reflections [I > 2σ(I)].
Index abstract Intramolecular hydrogen bonding is important on the tautomeric properties and the type of aldehyde plays a vital role of the
enol-imine and keto-amine properties of the Schiff base ligand.
相似文献
118.
Kyeongchan Noh Minsu Kim Sang-Hyun Lee Hwang-Sik Yun Tae-Hyeon Lim Yeongho Choi Ki-Ju Kim Yiran Jiang Keonwon Beom Minju Kim Young-Gwang Kim Pilwoo Lee Nuri Oh Bong Hoon Kim Chansun Shin Hyun Ho Lee Tae-Sik Yoon Moonsub Shim Seong-Yong Cho 《Current Applied Physics》2019,19(9):998-1005
The aging of ZnO nanoparticles in quantum dot light-emitting diode (QD-LED) structures was studied. Coarsening of as-synthesized ZnO nanoparticles is observed in both solution and thin film structures, which potentially deteriorates the performance of QD-LED devices over time. First, the temperature effect on ZnO coarsening was investigated, and it was revealed that aging of ZnO nanoparticles is faster at higher temperature due to a diffusion-controlled mechanism of nanoparticle coarsening. To observe aggregation of ZnO in the film state, the electron transporting part (ZnO/Al) of the QD-LED structure was prepared. The current density of a ZnO film and an electron-only device (QD/ZnO between two electrodes) was also measured. Resistance of the film increased as a function of aging time, which corresponded with observations of the ZnO film by optical microscopy. Aggregation of ZnO nanoparticles was directly measured by the root-mean-square value using atomic force microscopy. Ethanolamine (EA) stabilizer was added to the ZnO solution to disperse the ZnO nanoparticles without aggregation. The effect of EA on the surface passivation of the ZnO found to suppress pinhole formation, as revealed by scanning electron microscopy observations. Finally, the device lifetime was measured for QD-LEDs with EA-stabilized ZnO to understand the effect of ZnO aging on long-term QD-LED device operation. 相似文献
119.
Nuri Akkaş 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1978,29(1):92-99
Summary An adiabatic gas-filled bubble in a viscous, incompressible liquid is subjected to a tension wave in the form of a step function in time. The governing equation is solved numerically. It is shown that there exists a dynamic tension threshold, similar to the Blake threshold in the static case, beyond which the bubble in the liquid will grow infinitely. The effec of the fluid viscosity on the forced oscillations of the bubble is discussed. Critical dynamic radii and critical dynamic pressures are given for a wide range of the radius of the bubble at rest, for both the viscous and inviscid liquids. The collapse mechanism of a bubble subjected to an exponentially decaying tension wave is explained.
Zusammenfassung Eine adiabatische Gasblase in einer zähen inkompressiblen Flüssigkeit wurde unter dem Einfluss einer zeitlich diskontinuierlichen Spannungswelle untersucht. Die Gleichungen wurden numerisch gelöst. Es wurde gezeigt, dass eine dynamische Spannungs-Schwelle ähnlich zur Blake-Schwelle des statischen Falles vorhanden ist. Wenn diese überschritten wird, wächst die Blase in der Flüssigkeit unbegrenzt. Die Wirkung der Zähigkeit auf die erzwungenen Blasenschwingungen wurde diskutiert. Kritische dynamische Radien und Drücke wurden für einen breiten Radiusbereich der Blase im Ruhezustand für zähe und reibungsfreie Flüssigkeiten gegeben. Der Zusammenbruch einer Blase in einer exponentiell gedämpften Spannungswelle wird erläutert.相似文献
120.
In this paper, uniform convergence of the generalized exponential (GE) integrals is investigated. We also study the continuity,
differentiability, summability and asymptotic behaviour of GE integrals. Then we give an accurate and efficient computation
algorithm for these integrals. 相似文献