全文获取类型
收费全文 | 135篇 |
免费 | 10篇 |
专业分类
化学 | 93篇 |
力学 | 7篇 |
数学 | 10篇 |
物理学 | 35篇 |
出版年
2023年 | 3篇 |
2022年 | 19篇 |
2021年 | 10篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 9篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 7篇 |
2013年 | 14篇 |
2012年 | 5篇 |
2011年 | 11篇 |
2010年 | 4篇 |
2009年 | 5篇 |
2008年 | 3篇 |
2007年 | 6篇 |
2006年 | 4篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2000年 | 1篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 2篇 |
排序方式: 共有145条查询结果,搜索用时 15 毫秒
61.
Rheological Characterization of Alumina Ceramic Suspensions in Presence of a Dispersant and a Binder
Asad U. Khan Nasir Mahmood Paul F. Luckham 《Journal of Dispersion Science and Technology》2013,34(8):1210-1217
The rheological responses of aqueous alumina suspensions, stabilized with an organic polyvalent salt dispersant called “Aluminon,” and including a poly(vinyl) alcohol (PVA) binder, are described in this study. It is observed that the addition of PVA, without any dispersant does not significantly influence the rheology. However, in the presence of the dispersant the rheology is affected significantly. At a given concentration of the dispersant, the viscosity, the storage and loss modulii all increase with the PVA concentration. Also, for a given concentration of the PVA, the viscosity, the storage and loss modulii values increases as the concentration of the dispersant is increased. At relatively low PVA concentrations, an excess concentration of the dispersant, causes flocculation of the particles in the suspension by a reduction of the electrostatic (double layer) effect. On the contrary, at higher concentrations of the PVA the flocculation of the suspension occurs via a depletion mechanism. 相似文献
62.
Shakir M Abbasi A Azam M Khan AU 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(5):1866-1875
The Schiff base ligand, N,N'-bis-(2-thiophenecarboxaldimine)-3,3'-diaminobenzidine (L) obtained from condensation of 2-thiophenecarboxaldehyde and 3,3'-diaminobenzidine, was used to synthesize the complexes of type, [M2L2]Cl4 [M=Co(II), Ni(II), Cu(II), Cd(II) and Hg(II)]. The newly synthesized ligand (L) was characterized on the basis of the results of elemental analysis, FT-IR, 1H NMR, 13C NMR, mass spectroscopic studies and single crystal X-ray crystallography. The characteristic resonance signals in 1H NMR and 13C NMR spectra indicated the presence of azomethine group as a result of condensation reaction. The stoichiometry, bonding and stereochemistries of complexes were ascertained on the basis of results of elemental analysis, magnetic susceptibility measurements, molar conductance and spectroscopic studies viz., FT-IR, 1H and 13C NMR, UV-vis and EPR. EPR, UV-vis and magnetic moment data revealed an octahedral geometry for complexes with distortion in Cu(II) complex and conductivity data show 1:2 electrolytic nature of complexes. Absoption and fluorescence spectroscopic studies supported that Schiff base ligand L and its Co(II), Ni(II) and Cu(II) complexes exhibited significant binding to calf thymus DNA. The complexes exhibited higher affinity to calf thymus DNA than the free Schiff base ligand L. 相似文献
63.
Jihad H. Asad 《Journal of statistical physics》2013,150(6):1177-1182
The equivalent resistance between the origin and the lattice site (2n,0,0), in an infinite Face Centered Cubic (FCC) network consisting from identical resistors each of resistance R, has been evaluated analytically and numerically. The asymptotic behavior of the equivalent resistance has been also investigated. Finally, some numerical values for the equivalent resistance are presented. 相似文献
64.
A characterization of a weight $v$ governing the boundedness/compactness of the weighted kernel operator $K_v$ in variable exponent Lebesgue spaces $L^{p(\cdot )}$ is established under the log-Hölder continuity condition on exponents of spaces. The kernel operator involves, for example, weighted variable parameter fractional integral operators. The distance between $K_v$ and the class of compact integral operators acting from $L^{p(\cdot )}$ to $L^{q(\cdot )}$ (measure of non-compactness) is also estimated from above and below. 相似文献
65.
Critical anomaly and finite size scaling of the self-diffusion coefficient for Lennardben Jones fluids by non-equilibrium molecular dynamic simulation 下载免费PDF全文
We use non-equilibrium molecular dynamics simulations to calculate the self-diffusion coefficient, D, of a Lennard-Jones fluid over a wide density and temperature range. The change in self-diffusion coefficient with temperature decreases by increasing density. For density ρ* = ρσ3 = 0.84 we observe a peak at the value of the self-diffusion coefficient and the critical temperature T* = kT/ε = 1.25. The value of the self-diffusion coefficient strongly depends on system size. The data of the self-diffusion coefficient are fitted to a simple analytic relation based on hydrodynamic arguments. This correction scales as N-α, where α is an adjustable parameter and N is the number of particles. It is observed that the values of α < 1 provide quite a good correction to the simulation data. The system size dependence is very strong for lower densities, but it is not as strong for higher densities. The self-diffusion coefficient calculated with non-equilibrium molecular dynamic simulations at different temperatures and densities is in good agreement with other calculations from the literature. 相似文献
66.
Anastasios Stergiou Karam Asad Andreas Kourtellaris Dr. Nikos Chronakis Dr. Nikos Tagmatarchis 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(22):5751-5756
Bisazafullerene (C59N)2 has been functionalized under aerobic conditions with cyclo-[2]-octylmalonate through a Mannich-type reaction, furnishing the corresponding monoadduct. A regioselective tether-directed Bingel cyclopropanation reaction was then carried out on the azafullerene core to yield a single bisadduct. Spectroscopic analysis of the formed bisadduct showed it to have a C1 symmetrical structure, making it inherently chiral. Single-crystal X-ray analysis revealed the addition pattern of the azafullerene bisadduct to be equatorialface. Examination of the optical properties showed the evolution of new absorption bands, which can be used as signatures for the characterization of equatorialface bisadducts of C59N. Finally, redox assays showed that the LUMO level of the equatorialface bisadduct was increased compared to that of the parent (C59N)2. 相似文献
67.
Novel Pyrazoline‐based Organometallic Compounds Containing Ferrocenyl and Quinoline units: Synthesis,Characterization and Microbial susceptibilities 下载免费PDF全文
Humaira Parveen Raedah Aiyed Suliman Alatawi Meshari A. Alsharif Mohammed Issa Alahmdi Sayeed Mukhtar Salman Ahmad Khan Sadaf Hasan Asad U. Khan 《应用有机金属化学》2018,32(4)
Some novel pyrazoline‐based organometallic compounds were synthesized as new leads in antimicrobial chemotherapy. The structures of compounds were elucidated by different spectroscopic techniques and elemental analyses. All compounds were investigated for in vitro antimicrobial studies against fifteen ATTC bacterial and fungal strains. The microbial susceptibility of these compounds revealed that all the tested compounds gave good minimum inhibitory concentration (MIC) values against the tested organisms that are either similar or even better than the reference drugs amoxicillin and fluconazole, which gave MIC values 8‐64 μg/ml against bacterial and 64 μg/ml against fungal strains, respectively. Among all compounds, compound ( 4d ) 1‐(5‐(4‐chlorophenyl)‐3‐ferrocenyl‐4,5‐dihydropyrazol‐1‐yl)‐2‐quinolin‐8‐yloxy) ethanone, emerged out the most promising antimicrobial organometallic derivative with MIC values against all the strains ranging from 8‐32 μg/ml. Other compounds gave a range of MIC values between 16‐64 μg/ml against S. bovis, 16‐32 μg/ml against E. coli, and C. tropicalis except compound ( 4d) which gave MIC 8 μg/ml against S. bovis and E. coli, whereas 32 μg/ml against C. tropicalis. Collectively, these compounds gave a lower MIC value between 32‐64 μg/ml against both of the biofilm forming strains namely, P. aeruginosa and S. mutans. The results of microbial susceptibility concluded that these novel organometallic compounds are new leads in antimicrobial chemotherapy and can be very useful for further optimization work on microbial chemotherapy. 相似文献
68.
69.
70.