全文获取类型
收费全文 | 142篇 |
免费 | 1篇 |
专业分类
化学 | 74篇 |
晶体学 | 5篇 |
力学 | 9篇 |
数学 | 12篇 |
物理学 | 43篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2018年 | 7篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2014年 | 12篇 |
2013年 | 10篇 |
2012年 | 8篇 |
2011年 | 8篇 |
2010年 | 12篇 |
2009年 | 5篇 |
2008年 | 8篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 5篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有143条查询结果,搜索用时 31 毫秒
101.
Determination of nitrosamines in preserved sausages by solid-phase extraction-micellar electrokinetic chromatography 总被引:3,自引:0,他引:3
Sanches Filho PJ Rios A Valcárcel M Zanin KD Caramão EB 《Journal of chromatography. A》2003,985(1-2):503-512
A new methodology for extraction, pre-concentration and analysis of nitrosamines in meat derived products was developed. The samples (canned sausages) were distilled in vacuum steam and the nitrosamines were pre-concentrated by solid-phase extraction with active carbon. Then, micellar electrokinetic chromatography was used for the separation and determination of the different nitrosamines contained in a real sample and gas chromatography with mass spectrometry detection was used as the confirmation technique. The method allowed the determination of nitrosamine compounds at trace levels with relative standard deviation ranging from 4.0 to 22%. 相似文献
102.
I. E. Zanin K. B. Aleinikova M. M. Afanasiev M. Yu. Antipin 《Journal of Structural Chemistry》2004,45(5):844-848
The structure of Zn3P2 (P 42/nmc, a = b = 8. 0785 Å, c = 11. 3966 Å) was solved and refined to R = 3. 2% in a precision X-ray diffraction experiment (λ-MoK
a, graphite monochromator on a primary beam, 27,496 reflections) . Interatomic distances and bond angles have been determined. The fcc lattice of the structure is built from phosphorus atoms, and the zinc atoms occupy 3/4 of all tetrahedral voids; the structure is described by two equivalent models where 1/4 occupied (by zinc atoms) and 1/4 vacant voids change places. The zinc atoms that occupy the voids following the diamond principle do not change places.Original Russian Text Copyright © 2004 by I. E. Zanin, K. B. Aleinikova, M. M. Afanasiev, and M. Yu. Antipin__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 889–892, September–October, 2004. 相似文献
103.
Adriano?Zanin?ZambomEmail author Julian?A.?A.?Collazos Ronaldo?Dias 《Journal of Global Optimization》2016,64(4):803-823
In real-time trajectory planning for unmanned vehicles, on-board sensors, radars and other instruments are used to collect information on possible obstacles to be avoided and pathways to be followed. Since, in practice, observations of the sensors have measurement errors, the stochasticity of the data has to be incorporated into the models. In this paper, we consider using a genetic algorithm for the constrained optimization problem of finding the trajectory with minimum length between two locations, avoiding the obstacles on the way. To incorporate the variability of the sensor readings, we propose a modified genetic algorithm, addressing the stochasticity of the feasible regions. In this way, the probability that a possible solution in the search space, say x, is feasible can be derived from the random observations of obstacles and pathways, creating a real-time data learning algorithm. By building a confidence region from the observed data such that its border intersects with the solution point x, the level of the confidence region defines the probability that x is feasible. We propose using a smooth penalty function based on the Gaussian distribution, facilitating the borders of the feasible regions to be reached by the algorithm. 相似文献
104.
Oil-containing gelatin-gum Arabic microparticles were prepared by complex coacervation followed by crosslinking with glutaraldehyde or transglutaminase. A fluorescent mixture, khusimyl dansylate (KD) as the fluorescent compound mixed to the vetiver essential oil, was used as oil model. The effect of the type of crosslinking of the coacervated gelatin-gum Arabic membrane, the physical state of microparticles, wet or freeze-dried and the type of release media, aqueous with surfactants, Sodium Dodecyl Sulphate (sds) or Tween 80 (tw) and anhydrous ethanol as organic media on the release rate of the KD from the microparticles, was experimentally investigated.It was shown that the oil was dispersed uniformly throughout the microparticles and the chemical crosslinked microparticles were more resistant to swelling, presenting smaller sizes after hydration. Also the crosslinking effect, transglutaminase or glutaraldehyde, could be confirmed by the integrity of the crosslinked gelatin-gum Arabic microparticles after incubation in the aqueous sds media, compared to complete dissolution of the uncrosslinked microparticles in this media.The cumulative fluorescent KD release from the gelatin-gum Arabic microparticles decreased in the following order of dissolution media: anhydrous ethanol > tw > sds and the wet microparticles have shown a faster KD release than freeze-dried ones. A mathematical model was used to estimate the diffusion coefficient (D). The chemically crosslinked gelatin-gum Arabic microparticles ensured a pronounced retard effect in the KD diffusion, presenting a D varying from 0.02 to 0.6 × 10−11 cm2/s, mainly in an aqueous media, against D varying from 1.05 to 13.9 × 10−11 cm2/s from the enzymatic crosslinked microparticles. 相似文献
105.
Flow past model wings is experimentally investigated in a subsonic wind tunnel at large angles of attack at which the laminar boundary layer separates near the leading edge of the wing (flow stall). The object of the study was the flow structure within the separation zone. The carbon-oil visualization of surface streamlines used in the experiments showed that in the separation zone there exist one or more pairs of large-scale vortices rotating in the wing plane. Certain general properties of the vortex structures in the separation zone are found to exist, whereas the flow patterns may differ depending on the model aspect ratio, the yaw angle, and other factors. 相似文献
106.
A. A. Maslov A. A. Sidorenko A. D. Budovskiy B. Yu. Zanin V. V. Kozlov B. V. Postnikov V. P. Fomichev 《Journal of Applied Mechanics and Technical Physics》2010,51(2):211-217
A subsonic flow around a cone mounted at an angle of attack is considered. A separated flow is formed on the cone with formation
of a pair of large-scale streamwise vortices arranged symmetrically or asymmetrically, depending on flow parameters. The possibility
of controlling the vortex flow by means of an electric discharge is studied in experiments. It is demonstrated that the use
of an electric discharge makes it possible both to transform an asymmetric flow to symmetric and to generate directed asymmetry.
Controlling the flow asymmetry, in turn, allows the side force direction to be controlled. 相似文献
107.
Luiza P. V. Calsavara Flávio F. De Moraes Gisella M. Zanin 《Applied biochemistry and biotechnology》1999,79(1-3):789-806
The enzyme cellobiase Novozym 188, which is used for improving hydrolysis of bagasse with cellulase, was characterized in
its commercial available form and integrated kinetic models were applied to the hydrolysis of cellobiose. The specific activity
of this enzyme was determined for pH values from 3.0–7.0, and temperatures from 40–75°C, with cellobiose at 2 g/L. Thermal
stability was measured at pH 4.8 and temperatures from 40–70°C. Substrate inhibition was studied at the same pH, 50°C, and
cellobiose concentrations from 0.4–20 g/L. Product inhibition was determined at 50°C, pH 4.8, cellobiose concentrations of
2 and 20 g/L, and initial glucose concentration nearly zero or 1.8 g/L. The enzyme has shown the greatest specific activity,
17.8 U/mg, at pH 4.5 and 65°C. Thermal activation of the enzyme followed Arrhenius equation with the Energy of Activation
being equal to 11 kcal/mol for pH values 4 and 5. Thermal deactivation was adequately modeled by the exponential decay model
with Energy of Deactivation giving 81.6 kcal/mol. Kinetics parameters for substrate uncompetitive inhibition were: Km=2.42 mM, V
max=16.31 U/mg, Ks=54.2 mM. Substrate inhibition was clearly observed above 10 mM cellobiose. Product inhibition at the concentration studied has usually doubled the time necessary to reach the same conversion
at the lower temperature tested. 相似文献
108.
Matioli Graciette Zanin Gisella M. de Moraes Flávio F. 《Applied biochemistry and biotechnology》2000,84(1-9):955-962
The production of cyclodextrins (CDs) by cyclodextrin-glycosyl-transferase (CGTase) from Bacillus firmus was studied, with respect to the effect of the source of starch upon CD yield and on the selectivity for producing γ-CD.
Cyclodextrin production tests were run for 24 h at 50°C, pH 8.0, and 1 mg/L of CGTase, and substrates were maltodextrin or
the starches of rice, potato, cassava, and corn hydrolyzed up to D. E. 10. Cornstarch was the best substrate for producing
γ-CD. Later, glycyrrhizin (2.5% [w/v]), which forms a stable complex with γ-CD, was added to the cornstarch reaction medium
and increased the yield of γ-CD to about four times that produced with only maltodextrin, but the total yield of CDs remained
practically unchanged. Therefore, the results showed that the studied CGTase is capable of giving relatively high yield of
γ-CD in the presence of glycyrrhizin as complexant and cornstarch as substrate. 相似文献
109.
Zanin Gisella M. Santana Cesar C. Bon Elba P. S. Giordano Raquel C. L. de Moraes Flávio F. Andrietta Silvio R. Neto Carlos Coelho De Carvalho Macedo Isaias C. Lahr Fo. Djalma Ramos Luiz P. Fontana José D. 《Applied biochemistry and biotechnology》2000,84(1-9):1147-1161
Brazil is the largest producer of bioethanol, and sugarcane is the main raw material. Bioethanol, is produced by both batch
and continuous processes, and in some cases, flocculating yeast is use. This article analyzes the Bracilian Ethanol Program.
for the 1996–1997 havest, Brazil produced 14.16 billion L of ethanol and 13.8 million metrict of sugar, from 286 million metrict
of sugarcane. These products were produced by 328 industries inactivity, with 101 autonomousethanol plants producing only
ethanol, and 227 sugar mills producing sugar and ethanol. The sugar-ethanol market reaches about 7.5 billion US$/yr, accounting
for direct and indirect revenues. 相似文献
110.
Zanin M 《Chaos (Woodbury, N.Y.)》2008,18(1):013119
The existence of forbidden patterns, i.e., certain missing sequences in a given time series, is a recently proposed instrument of potential application in the study of time series. Forbidden patterns are related to the permutation entropy, which has the basic properties of classic chaos indicators, such as Lyapunov exponent or Kolmogorov entropy, thus allowing to separate deterministic (usually chaotic) from random series; however, it requires fewer values of the series to be calculated, and it is suitable for using with small datasets. In this paper, the appearance of forbidden patterns is studied in different economical indicators such as stock indices (Dow Jones Industrial Average and Nasdaq Composite), NYSE stocks (IBM and Boeing), and others (ten year Bond interest rate), to find evidence of deterministic behavior in their evolutions. Moreover, the rate of appearance of the forbidden patterns is calculated, and some considerations about the underlying dynamics are suggested. 相似文献