全文获取类型
收费全文 | 46篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
化学 | 16篇 |
晶体学 | 1篇 |
数学 | 14篇 |
物理学 | 17篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2015年 | 1篇 |
2013年 | 2篇 |
2012年 | 1篇 |
2011年 | 1篇 |
2010年 | 1篇 |
2009年 | 3篇 |
2008年 | 2篇 |
2007年 | 2篇 |
2006年 | 2篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 6篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有48条查询结果,搜索用时 15 毫秒
1.
Ahmed Waqar Chowdhury Z. Z. Kazi S. N. Johan MR. Akram Naveed Oon C. S. Abdelrazek Ali H. 《Journal of Thermal Analysis and Calorimetry》2021,144(4):1517-1534
Journal of Thermal Analysis and Calorimetry - In recent decades, the growth of heat transfer using nanomaterials in the conventional base fluid has caught the attention of researchers... 相似文献
2.
In quasi-steady operation, convection currents in a Bridgmandevice, used for producing a semi-conductor crystal, createinhomogeneities that may make the crystal unusable. It has oftenbeen suggested that additional forces due to rotation or magnetismmight be efficacious in reducing the segregation of the elementsof the alloy. It has been found that, over a wide range of rotationrates, there is no improvement in performance due to rotationabout the vertical axis. However, numerical results that havebeen obtained previously (Lee & Pearlstein, J. Crys. Growth240, 2002) indicate that, when effects of centrifugal buoyancyare introduced, a substantial reduction in segregation is achieved.In the work reported here, by contrast, in which we extend previouslarge-Rayleigh-number asymptotic analysis to include centrifugalbuoyancy, we find no improvement in radial segregation, butrather increasing segregation with increasing rotation rate. 相似文献
3.
In this paper, the surface acoustic wave velocity results acquired from the inspection of specially manufactured and characterised alumina ceramic materials are presented. Ultrasonic velocity data of alumina-based ceramics in the range 60-100% theoretical density was generated utilising non-contacting laser-ultrasonic measurements based on laser generation and detection of surface acoustic waves with the objective of creating a routine technique for industrial advanced alumina inspection. With linear fitting the surface acoustic wave velocity data serves as a calibration graph for using laser ultrasonics for routine monitoring of alumina. A second laser ultrasonic technique based on the laser generation and foil transducer detection of surface acoustic waves was used to validate the surface acoustic wave velocities measured by the laser generation/detection technique. 相似文献
4.
S.D. Gopal Ram G. Ravi MR. Manikandan T. Mahalingam M. Anbu Kulandainathan 《Superlattices and Microstructures》2011,50(4):296-302
In the present work, a controlled growth of ZnO nanostructures by manipulating Zn metal ion concentration by the chelating action of ethylene diaminetetra acetic acid in hydrothermal method is studied. EDTA produces metal–chelate complex by the formation of bidentate ligand with Zn2+ in the solution and diminishes the reactivity of Zn metal cations. Concentration of EDTA in the mother solution was varied in different ranges like 3, 5 and 10 mM while retaining the zinc metal salt and the NaOH concentration the same. Three different morphologies of wurtzite structured ZnO nanostructures such as nanorods-bunch, separate/discrete uniformly sized hexagonal nanorods and tapered flower petals like shapes are achieved by 3, 5 and 10 mM strengths of EDTA, respectively. The medium concentration 5 mM of EDTA is found to have moderate control over producing ZnO nanostructures of uniform diameter and a high aspect (length to diameter) ratio. An array of vertically aligned free standing ZnO nanorods with uniform spacing is successfully achieved by the addition of 5 mM of EDTA in the mother solution and the same is studied for its fluorescence property at an excitation of 325 nm and it has exhibited a characteristic UV emission of ZnO around 383 nm. 相似文献
5.
6.
We classify the maximal irreducible periodic subgroups of PGL(q,
), where
is a field of positive characteristic p transcendental over its prime subfield, q = p is prime, and
× has an element of order q. That is, we construct a list of irreducible subgroups G of GL(q,
) containing the centre
×1
q
of GL(q,
), such that G/
×1
q
is a maximal periodic subgroup of PGL(q,
), and if H is another group of this kind then H is GL(q,
)-conjugate to a group in the list. We give criteria for determining when two listed groups are conjugate, and show that a
maximal irreducible periodic subgroup of PGL(q,
) is self-normalising.
相似文献
7.
Ellen Matthaei-Schulz Tony Flaherty Colm Flannery Tony Randles Odile Lefeuvre Pavel Zinin Laurent Robert 《Mikrochimica acta》2000,133(1-4):11-15
For quantitative assessment of the properties of hard coatings there is an increasing demand for testing methods with high
reliability of the test results, especially concerning the independence of the method and the comparability between different
laboratories. This includes the knowledge about all the factors which influence the test procedure itself, determination of
best testing conditions, testing of these conditions in round-robins to get a view of the comparability of results, and formulation
of guidelines for standardization. In a European project several test methods for hard coatings on steel were investigated
for this purpose and the elastic moduli of the coating and coating thickness were determined non-destructively by means of
quantitative acoustic microscopy. This method and the instruments available had not yet been certified in the fields of coatings
simply owing to the absence of standardised signal processing, followed by the determination of sound velocities and materials
parameter extraction. For this purpose four laboratories carried out investigations and measurements on reference samples
and on two types of hard coatings (titanium nitride and C-doped chromium) on M2 tool steel. 相似文献
8.
What is new in the field of neutrino detection? In addition to new projects probing both the low and high ends of the neutrino energy scale, an inexpensive, effective technique is being developed to allow tagging of antineutrinos in water Cherenkov (WC) detectors via the addition to water of a solute with a large neutron cross-section and energetic γ daughters. Gadolinium is an excellent candidate since in recent years it has become very inexpensive, now less than $8 per kilogram in the form of commercially available gadolinium trichloride. This non-toxic, non-reactive substance is highly soluble in water. Neutron capture on gadolinium yields an 8.0 MeV gamma cascade easily seen in detectors like Super-Kamiokande. The uses of GdCl3 as a possible upgrade for the Super-Kamiokande detector — with a view toward improving its performance as an antineutrino detector for supernova neutrinos and reactor neutrinos — are discussed, as are the ongoing R&;D efforts which aim to make this dream a reality within the next two years. 相似文献
9.
10.
M. R. Flannery E. Oks 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(1):27-31
A Rydberg atom embedded in a plasma can experience penetration by slowly moving electrons within its volume. The original
pure Coulomb potential must now be replaced by a screened Coulomb potential which contains either a screening length Rs or a screening factor A = Rs
-1 . For any given discrete energy level, there is a Critical Screening Factor (CSF) Ac beyond which the energy level disappears (by merging into the continuum). Analytical results are obtained for the classical
dependence of the energy on the screening factor, for the CSF, and for the critical radius of the electron orbit for Circular
Rydberg States (CRS) in this screened Rydberg atom. The results are derived for any general form of the screened Coulomb potential
and are applied to the particular case of the Debye potential. We also show that CRS can temporarily exist above the ionization
threshold and are therefore the classical counterparts of quantal discrete states embedded into continuum. The results are
significant not only to Rydberg plasmas, but also to fusion plasmas, where Rydberg states of multi-charged hydrogen-like ions
result from charge exchange with hydrogen or deuterium atoms, as well as to dusty/complex plasmas. 相似文献