全文获取类型
收费全文 | 333篇 |
免费 | 7篇 |
国内免费 | 2篇 |
专业分类
化学 | 181篇 |
晶体学 | 14篇 |
力学 | 28篇 |
数学 | 56篇 |
物理学 | 63篇 |
出版年
2022年 | 7篇 |
2021年 | 3篇 |
2020年 | 9篇 |
2019年 | 2篇 |
2018年 | 8篇 |
2017年 | 9篇 |
2016年 | 7篇 |
2015年 | 10篇 |
2014年 | 11篇 |
2013年 | 20篇 |
2012年 | 25篇 |
2011年 | 39篇 |
2010年 | 20篇 |
2009年 | 9篇 |
2008年 | 14篇 |
2007年 | 12篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 12篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 9篇 |
1994年 | 9篇 |
1993年 | 4篇 |
1992年 | 8篇 |
1991年 | 2篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1984年 | 2篇 |
1982年 | 3篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1975年 | 3篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1964年 | 1篇 |
1961年 | 2篇 |
排序方式: 共有342条查询结果,搜索用时 15 毫秒
71.
72.
Rasika Prabhu Rasmus Klitkou Grigori A. Medvedev James M. Caruthers 《Journal of Polymer Science.Polymer Physics》2013,51(8):687-697
The linear viscoelastic behavior in dynamic shear and tensile creep at temperatures from −30 to 70 °C is measured for an styrene–butadiene rubber (SBR) elastomer cured with dicumyl peroxide to crosslinking densities between 0 and 23.5 × 10−5 mol/cm3. The G′, G″, and tan δ isotherms are analyzed by time–temperature superposition (TTS), where the tan δ master curves are consistent with those of Mancke and Ferry. However, to achieve the TTS in the lightly crosslinked SBR systems, an anomalous vertical shift is required in the narrow temperature region from 10 to 30 °C. The vertical shift factor in this temperature region is not the standard from rubber elasticity. No anomalous behavior is detected in the equilibrium modulus, which is a linear function of temperature in accordance with the classical theory of rubber elasticity. In contrast to SBR, standard vertical shifts are required to effect TTS for uncrosslinked polybutadiene and an ethylene propylene diene monomer elastomer. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013 相似文献
73.
We study a PH/G/1 queue in which the arrival process and the service times depend on the state of an underlying Markov chain J(t) on a countable state spaceE. We derive the busy period process, waiting time and idle time of this queueing system. We also study the Markov modulated EK/G/1 queueing system as a special case. 相似文献
74.
Large sample inference from single server queues 总被引:1,自引:0,他引:1
Problems of large sample estimation and tests for the parameters in a single server queue are discussed. The service time and the interarrivai time densities are assumed to belong to (positive) exponential families. The queueing system is observed over a continuous time interval (0,T] whereT is determined by a suitable stopping rule. The limit distributions of the estimates are obtained in a unified setting, and without imposing the ergodicity condition on the queue length process. Generalized linear models, in particular, log-linear models are considered when several independent queues are observed. The mean service times and the mean interarrival times after appropriate transformations are assumed to satisfy a linear model involving unknown parameters of interest, and known covariates. These models enhance the scope and the usefulness of the standard queueing systems.Partially supported by the U. S. Army Research Office through the Mathematical Sciences Institute of Cornell University. 相似文献
75.
A series of commercial organotin compounds was screened for efficacy against the three insect species Dysdercus cingulatus (cotton stainer), Anophelese stephensi (mosquito) and Musca domestica (house fly). Tributyltin species in the general order Bu3SnCl>(Bu3Sn)2O>Bu3Sn(linoleate) were more effective than two triphenyltin compounds. Tricyclohexyltin hydroxide, dimethyltin chloride, phenyltin trichloride and a diethyltin dichloridephenanthroline adduct were less effective. 相似文献
76.
J. B. C. Efrem D'Sa P. A. Bhobe K. R. Priolkar A. Das P. S. R. Krishna P. R. Sarode R. B. Prabhu 《Pramana》2004,63(2):227-232
In this paper we report low temperature neutron diffraction studies on MnSe in order to understand the anomalous behaviour
of their magnetic and transport properties. Our study indicates that at low temperatures MnSe has two coexisting crystal structures,
high temperature NaCl and hexagonal NiAs. NiAs phase appears below 266 K and is antiferromagnetically ordered at all temperatures
while the NaCl phase orders antiferromagnetically at 130 K. 相似文献
77.
Experimental Techniques - The conventional photoelastic method of stress freezing could not be employed for analysis of a Francis runner blade under hydraulic loading. The impasse was overcome by a... 相似文献
78.
A. Antony Muthu Prabhu Madi Fatiha Nouar Leila T. Anantha Raj Inmaculada Navarro-González Maria Jesús Periago Maria Josefa Yáñez-Gascón Horacio Pérez-Sánchez 《Journal of solution chemistry》2018,47(3):409-429
The interactions of the neurotransmitter dopamine (DA) with β-cyclodextrin and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) was characterized using UV–visible, 2D fluorescence, 3D fluorescence, FT–IR, PXRD and SEM techniques. PM3, PM7 and DFT methods were used to optimize the structures of the inclusion complexes in the gas phase. The absorbance and fluorescence intensities of DA increased in the presence of CDs in aqueous solution. The binding energy, HOMO–LUMO energy gap and Mulliken atomic charges were computed for the inclusion complexes. NBO analysis revealed a greater number of intermolecular hydrogen bonds in DA:HP-β-CD. Experimental and theoretical results suggested that the DA molecule is deeply embedded in the cavities of both CDs. 相似文献
79.
Photometric determination of barium and calcium in lubricating oils and lubricating oil concentrates
K. S. Anand Prabhu Dayal O. N. Anand 《Fresenius' Journal of Analytical Chemistry》1969,247(5-6):310-312
Summary A rapid and sensitive method for the determination of barium and calcium in lubricating oils is described. It is based on the formation of barium chromate and calcium oxalate and the estimation of barium and calcium by determining chromium and oxalate ions. Results obtained are in close agreement with those obtained by the Standard IP Method.
Photometrische Barium- und Calciumbestimmung in Schmierölen und Schmierölkonzentraten
Zusammenfassung Die schnelle und empfindliche Methode beruht auf der Fällung der Elemente als Chromat bzw. Oxalat und der photometrischen Bestimmung des Chromats aus der Farbe seiner Lösung und des Oxalats durch Reaktion mit Permanganat. Die Analysenergebnisse stimmen gut mit denen nach der Standardmethode des Institute of Petroleum überein.相似文献
80.
The study of superparamagnetic Fe3O4/Ag nanocomposites have received great research attention due to their wide range of potential applications in biomedicine. In this report, an easy microemulsion reaction was employed to synthesis Fe3O4/Ag nanocomposites with self-aggregated branch like nanostructures. The Fe3O4 nanoparticles were initially prepared and subsequently AgNO3 was reduced as Ag by chemical reduction method. The results showed that the average size of the Fe3O4/Ag nanocomposites were in the range of 10 ± 2 nm. These nanoparticles were self-aggregated as a branch like nanostructure. The optical properties of Fe3O4 nanoparticles were modified with surface plasmon resonance of Ag nanoparticles. The observed saturation magnetization of superparamagnetic Fe3O4/Ag nanocomposites were 40 emu/g. 相似文献