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排序方式: 共有502条查询结果,搜索用时 19 毫秒
71.
Kucheyev SO Biener J Baumann TF Wang YM Hamza AV Li Z Lee DK Gordon RG 《Langmuir : the ACS journal of surfaces and colloids》2008,24(3):943-948
Atomic layer deposition (ALD) appears to be uniquely suited for coating substrates with ultrahigh aspect ratios (> or similar 10(3)), including nanoporous solids. Here, we study the ALD of Cu and Cu3N on the inner surfaces of low-density nanoporous silica aerogel monoliths. Results show that Cu depth profiles in nanoporous monoliths are limited not only by Knudsen diffusion of heavier precursor molecules into the pores, as currently believed, but also by other processes such as the interaction of precursor and reaction product molecules with pore walls. Similar behavior has also been observed for Fe, Ru, and Pt ALD on aerogels. On the basis of these results, we discuss design rules for ALD precursors specifically geared for coating nanoporous solids. 相似文献
72.
Iron Oxide Supported on Al2O3 Catalyst for Methane Decomposition Reaction: Effect of MgO Additive and Calcination Temperature 下载免费PDF全文
Ahmed S. Al‐Fatesh Anis H. Fakeeha Ahmed A. Ibrahim Wasim U. Khan H. Atia R. Eckelt Biswajit Chowdhury 《中国化学会会志》2016,63(2):205-212
Production of hydrogen is a challenging task and have significant impact in the recent scenario. The alumina supported iron oxide nanoparticle synthesized using non‐ionic surfactant Triton‐X was found very effective for steady production of hydrogen through methane decomposition reaction. The high surface area, easily reducible catalyst calcined at 500 °C and 800 °C temperature showed steady activity towards methane decomposition reaction. At a higher reaction temperature there was catalyst deactivation. The doping of MgO facilitated particle growth rendering the poor catalytic activity. The TPR study showed that reducibility of TPR was difficult in presence of MgO additive. The formation of Fe? Mg? Al solid solution confirmed by XRD study was found mainly responsible for the lower catalytic activity. The bamboo‐shaped carbon nanotube formed from 20 % Fe/Al2O3 catalyst which is mainly because of the poor wetting property of quasi‐liquid metal and carbon nanotube. 相似文献
73.
Hamza Jirari Ning Wu 《The European Physical Journal B - Condensed Matter and Complex Systems》2016,89(4):100
Optimal state transfer of a single two-level system (TLS) coupled to an Ohmic boson bath via off-diagonal TLS-bath coupling is studied by using optimal control theory. In the weak system-bath coupling regime where the time-dependent Bloch-Redfield formalism is applicable, we obtain the Bloch equation to probe the evolution of the dissipative TLS in the presence of a time-dependent external control field. By using the automatic differentiation technique to compute the gradient for the cost functional, we calculate the optimal transfer integral profile that can achieve an ideal transfer within a dimer system in the Fenna-Matthews-Olson (FMO) model. The robustness of the control profile against temperature variation is also analyzed. 相似文献
74.
Fadiel A Eichenbaum KD Hamza A Tan O Lee HH Naftolin F 《Current protein & peptide science》2007,8(1):29-37
Electrostatic and electrochemical properties of bio-molecules, such as proteins, are governed by energy parameters that are, in part dependent on its folding. Disruption of this process can lead to the development of complex, multisystem diseases whose presentation may be organ-dependent. Examples include cystic fibrosis, alpha-1 antitrypsin deficiency, and Alzheimer disease. In addition to explaining exotic pathologic syndromes, an understanding of protein folding mechanisms may facilitate the understanding of less complex diseases and allow the development of novel therapeutic approaches. 相似文献
75.
Shir DJ Jeon S Liao H Highland M Cahill DG Su MF El-Kady IF Christodoulou CG Bogart GR Hamza AV Rogers JA 《The journal of physical chemistry. B》2007,111(45):12945-12958
This Feature Article reviews recent work on an optical technique for fabricating, in a single exposure step, three-dimensional (3D) nanostructures with diverse structural layouts. The approach, which we refer to as proximity field nanopatterning, uses conformable, elastomeric phase masks to pattern thick layers of transparent, photosensitive materials in a conformal contact mode geometry. Aspects of the optics, the materials, and the physical chemistry associated with this method are outlined. A range of 3D structures illustrate its capabilities, and several application examples demonstrate possible areas of use in technologies ranging from microfluidics to photonic materials to density gradient structures for chemical release and high-energy density science. 相似文献
76.
T. Schlathölter M.W. Newman T.R. Niedermayr G.A. Machicoane J.W. McDonald T. Schenkel R. Hoekstra A.V. Hamza 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(2):323-327
The emission of small (hydrogenated) carbon cluster ions CnHm
+
(n
=2-22) upon highly charged Xeq+ (q
=20-44) impact on C84 surfaces is studied by means of time-of-flight secondary ion mass spectrometry. The respective stage of hydrogenation/protonation
of a certain carbon cluster ion Cn
+
is a strong indication for its geometrical structure. From the cluster ion yield as a function of cluster size it can be
concluded, that the hydrogenation takes place after the initial carbon cluster formation. The carbon clusters seem to be emitted
as an entity in agreement with “equilibrium” and “shock wave” models.
Received 4 February 2000 相似文献
77.
Ibrahim Mahariq Ibrahim H. Giden Hamza Kurt Oleg V. Minin Igor V. Minin 《Optical and Quantum Electronics》2017,49(12):423
We theoretically study the forward and backward plane wave illuminations of hemicylindrical dielectric particles with different radii and refractive indices. Near field effects providing strong field enhancement and narrow beam width are obtained from hemicylindrical particles, which can be associated with whispering gallery modes (WGMs) and photonic nano-jets (PNJs). It should be noted that existence of PNJ and WGM effects depending on forward/backward light illuminations is studied for the first time in all-dielectric hemicylindrical particles. Compared to dielectric cylinders, hemicylindrical aided PNJs show relatively small influences of WGM regime, when exists, to PNJ behavior. Under the backward excitation, on the other hand, typical nano-jet is produced. The designed hemicylindrical structure could be implemented in high-resolution optical imaging and sensing applications. 相似文献
78.
Noureddine Bencheikh Mohamed Bouhrim Loubna Kharchoufa Omkulthom Mohamed Al Kamaly Hamza Mechchate Imane Es-safi Ahmed Dahmani Sabir Ouahhoud Soufiane El Assri Bruno Eto Mohamed Bnouham Mohammed Choukri Mostafa Elachouri 《Molecules (Basel, Switzerland)》2021,26(16)
Zizyphus lotus L. (Desf.) (Z. lotus) is a medicinal plant largely distributed all over the Mediterranean basin and is traditionally used by Moroccan people to treat many illnesses, including kidney failure. The nephrotoxicity of gentamicin (GM) has been well documented in humans and animals, although the preventive strategies against it remain to be studied. In this investigation, we explore whether the extract of Zizyphus lotus L. (Desf.) Fruit (ZLF) exhibits a protective effect against renal damage produced by GM. Indeed, twenty-four Wistar rats were separated into four equal groups of six each (♂/♀ = 1). The control group was treated orally with distilled water (10 mL/kg); the GM treated group received distilled water (10 mL/kg) and an intraperitoneal injection of GM (80 mg/kg) 3 h after; and the treated groups received ZLF extract orally at the doses 200 or 400 mg/kg and injected intraperitoneally with the GM. All treatments were given daily for 14 days. At the end of the experiment, the biochemical parameters and the histological observation related the kidney function was explored. ZLF treatment has significantly attenuated the nephrotoxicity induced by the GM. This effect was indicated by its capacity to decrease significantly the serum creatinine, uric acid, urea, alkaline phosphatase, gamma-glutamyl-transpeptidase, albumin, calcium, sodium amounts, water intake, urinary volume, and relative kidney weight. In addition, this effect was also shown by the increase in the creatinine clearance, urinary creatinine, uric acid, and urea levels, weight gain, compared to the rats treated only with the GM. The hemostasis of oxidants/antioxidants has been significantly improved with the treatment of ZLF extract, which was shown by a significant reduction in malondialdehydes levels. Histopathological analysis of renal tissue was correlated with biochemical observation. Chemical analysis by HPLC-DAD showed that the aqueous extract of ZLF is rich in phenolic compounds such as 3-hydroxycinnamic acid, catechin, ferulic acid, gallic acid, hydroxytyrosol, naringenin, p- coumaric Acid, quercetin, rutin, and vanillic acid. In conclusion, ZLF extract improved the nephrotoxicity induced by GM, through the improvement of the biochemical and histological parameters and thus validates its ethnomedicinal use. 相似文献
79.
80.
This paper establishes dynamical localization properties of certain families of unitary random operators on the d-dimensional lattice in various regimes. These operators are generalizations of one-dimensional physical models of quantum
transport and draw their name from the analogy with the discrete Anderson model of solid state physics. They consist in a
product of a deterministic unitary operator and a random unitary operator. The deterministic operator has a band structure,
is absolutely continuous and plays the role of the discrete Laplacian. The random operator is diagonal with elements given
by i.i.d. random phases distributed according to some absolutely continuous measure and plays the role of the random potential.
In dimension one, these operators belong to the family of CMV-matrices in the theory of orthogonal polynomials on the unit
circle. We implement the method of Aizenman-Molchanov to prove exponential decay of the fractional moments of the Green function
for the unitary Anderson model in the following three regimes: In any dimension, throughout the spectrum at large disorder
and near the band edges at arbitrary disorder and, in dimension one, throughout the spectrum at arbitrary disorder. We also
prove that exponential decay of fractional moments of the Green function implies dynamical localization, which in turn implies
spectral localization. These results complete the analogy with the self-adjoint case where dynamical localization is known
to be true in the same three regimes. 相似文献