全文获取类型
收费全文 | 115篇 |
免费 | 0篇 |
专业分类
化学 | 50篇 |
力学 | 15篇 |
数学 | 13篇 |
物理学 | 37篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2020年 | 3篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2014年 | 3篇 |
2013年 | 11篇 |
2012年 | 5篇 |
2011年 | 8篇 |
2010年 | 3篇 |
2009年 | 1篇 |
2008年 | 3篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2002年 | 5篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1977年 | 7篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 1篇 |
1971年 | 4篇 |
1969年 | 3篇 |
1968年 | 2篇 |
1965年 | 3篇 |
1964年 | 3篇 |
1961年 | 4篇 |
1959年 | 2篇 |
1958年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有115条查询结果,搜索用时 15 毫秒
41.
Thomsen AE Jensen H Jorgensen L van de Weert M Ostergaard J 《Colloids and surfaces. B, Biointerfaces》2008,63(2):243-248
Protein adsorption represents a considerable challenge in the development and production of macromolecular drugs. From an analytical point of view the adsorption process is difficult to study in an efficient way using currently available techniques. In this work potential and time dependent adsorption and adsorption kinetics of human insulin at an 1,2-dichloroethane-aqueous interface were studied using a novel electroanalytical approach based on measurements of interfacial capacitance. Two different types of measurements were performed; potential scans and time scans. In the potential scans, the capacitance was measured over a range of applied potential differences across the interface. The interfacial potential difference is linked to the charge at the interface. Adsorption of human insulin was detectable at a bulk phase insulin concentration as low as 0.1 μM as a negative shift in the potential of zero charge (pzc). Adsorption kinetics were further studied using time scans in which the interfacial capacitance was measured at a fixed applied interfacial potential difference. Using this approach it was possible to study how the adsorption kinetics and the shape of the time scan curves were related to the bulk concentration of insulin and the interfacial potential difference. The changes in capacitance could be described phenomenologically by pseudo-first-order kinetics at low concentrations of insulin except at positive interfacial potential differences and high insulin concentrations (≥0.25 μM) where a more complex shape of the time scans curves was observed. 相似文献
42.
McGoverin CM Engelbrecht P Geladi P Manley M 《Analytical and bioanalytical chemistry》2011,401(7):2283-2289
Undesired germination of cereal grains diminishes process utility and economic return. Pre-germination, the term used to describe
untimely germination, leads to reduced viability of a grain sample. Accurate and rapid identification of non-viable grain
is necessary to reduce losses associated with pre-germination. Viability of barley, wheat and sorghum grains was investigated
with near-infrared hyperspectral imaging. Principal component analyses applied to cleaned hyperspectral images were able to
differentiate between viable and non-viable classes in principal component (PC) five for barley and sorghum and in PC6 for
wheat. An OH stretching and deformation combination mode (1,920–1,940 nm) featured in the loading line plots of these PCs;
this water-based vibrational mode was a major contributor to the viable/non-viable differentiation. Viable and non-viable
classes for partial least squares-discriminant analysis (PLS-DA) were assigned from PC scores that correlated with incubation
time. The PLS-DA predictions of the viable proportion correlated well with the viable proportion observed using the tetrazolium
test. Partial least squares regression analysis could not be used as a source of contrast in the hyperspectral images due
to sampling issues. 相似文献
43.
Lane SR Sisay N Carney B Dannoon S Williams S Engelbrecht HP Barnes CL Jurisson SS 《Dalton transactions (Cambridge, England : 2003)》2011,40(1):269-276
Reactions of Re(V), tetradentate Schiff base complexes with tertiary phosphines have previously yielded both rearranged Re(V) and reduced Re(III) complexes. To further understand this chemistry, the rigid diiminediphenol (N(2)O(2)) Schiff base ligand sal(2)phen (N,N'-o-phenylenebis(salicylaldimine)) was reacted with (n-Bu(4)N)[ReOCl(4)] to yield trans-[ReOCl(sal(2)phen)] (1). On reaction with triphenylphosphine (PPh(3)), a rearranged Re(V) product cis-[ReO(PPh(3))(sal(2)phen*)]PF(6) (2), in which one of the imines was reduced to an amine during the reaction, and the reduced Re(III) products trans-[ReCl(PPh(3))(sal(2)phen)] (4) and trans-[Re(PPh(3))(2)(sal(2)phen)](+) (5) were isolated. Reaction of sal(2)phen with [ReCl(3)(PPh(3))(2)(CH(3)CN)] resulted in the isolation of [ReCl(2)(PPh(3))(2)(salphen)] (3). The compounds were characterized using standard spectroscopic methods, elemental analyses and single crystal X-ray crystallography. 相似文献
44.
This paper investigates optimization in dynamic environments where the numbers of optima are unknown or fluctuating. The authors present a novel algorithm, Dynamic Population Differential Evolution (DynPopDE), which is specifically designed for these problems. DynPopDE is a Differential Evolution based multi-population algorithm that dynamically spawns and removes populations as required. The new algorithm is evaluated on an extension of the Moving Peaks Benchmark. Comparisons with other state-of-the-art algorithms indicate that DynPopDE is an effective approach to use when the number of optima in a dynamic problem space is unknown or changing over time. 相似文献
45.
J.A.A. Engelbrecht I.J. van Rooyen A. Henry E. Janzén E.J. Olivier 《Physica B: Condensed Matter》2012,407(10):1525-1528
A peak in the reststrahlen region of SiC is analyzed in order to establish the origin of this peak. The peak can be associated with a thin damaged layer on the SiC wafers, and a relation is found between surface roughness and the height of this peak, by modeling the damaged layer as an additional layer when simulating the reflectivity from the wafers. 相似文献
46.
Simulation-based comparison of noise effects in wavelength modulation spectroscopy and direct absorption TDLAS 总被引:1,自引:0,他引:1
B. Lins P. Zinn R. Engelbrecht B. Schmauss 《Applied physics. B, Lasers and optics》2010,100(2):367-376
A simulative investigation of noise effects in wavelength modulation spectroscopy (WMS) and direct absorption diode laser
absorption spectroscopy is presented. Special attention is paid to the impact of quantization noise of the analog-to-digital
conversion (ADC) of the photodetector signal in the two detection schemes with the goal of estimating the necessary ADC resolution
for each technique. With laser relative intensity noise (RIN), photodetector shot noise and thermal amplifier noise included,
the strategies used for noise reduction in direct and wavelength modulation spectroscopy are compared by simulating two respective
systems. Results show that because of the combined effects of dithering by RIN and signal averaging, the resolutions required
for the direct absorption setup are only slightly higher than for the WMS setup. Only for small contributions of RIN an increase
in resolution will significantly improve signal quality in the direct scheme. 相似文献
47.
Andrus Salupere Martin Lints Jüri Engelbrecht 《Archive of Applied Mechanics (Ingenieur Archiv)》2014,84(9-11):1583-1593
In the present paper, formation of solitons in microstructured continuum, modelled by a hierarchical Korteweg–de Vries equation, is studied. The model equation is integrated numerically making use of the discrete Fourier transform-based pseudospectral method under different initial conditions. Main attention is paid to the formation of hidden solitons and applicability of the discrete spectral analysis. 相似文献
48.
Zusammenfassung Durch Vergleiche experimenteller Daten und quantenchemisch berechenbarer Größen (Protonenaffinitäten und H-Ladungsdichten) wird die Möglichkeit diskutiert, aus der chemischen Konstitution von Protonensäuren direkte Beziehungen zu ihrem aciden Verhalten in verschiedenen Medien abzuleiten. Die für Wasser und Eisessig als Solventien dabei erhaltenen linearen Korrelationen zwischen pK-Werten und berechneten Protonenaffinitäten erweisen sich als sinnvolle Ergänzung bisher bekannter Untersuchungen von Protolysereaktionen. Sie ermöglichen außerdem, Hinweise auf ungewöhnliches chemisches Verhalten von Säuren in diesen Lösungsmitteln zu erhalten. Die berechneten Ladungsdichten erweisen sich als nur bedingt brauchbare Größe für derartige Untersuchungen.
Mit 2 Abbildungen 相似文献
Quantum mechanical calculations and acidity of protonic acids
Comparing experimental results with data calculated by means of quantum chemical treatment (proton affinities and H-charge-densities) the possibility is discussed, to obtain informations about the acidic properties of proton acids from their chemical constitution. The linear correlations of calculated proton affinities and pK-values, as found for water and acetic acid as solvents, lead to some general considerations about protolysis reactions. They also allow to obtain indications to exceptional chemical behaviour of an acid in these solutions. Hydrogen charge densitites are found to be less useful for investigations of this kind.
Mit 2 Abbildungen 相似文献
49.
Alfred Engelbrecht 《Monatshefte für Chemie / Chemical Monthly》1961,92(6):1269-1272
Zusammenfassung Darstellung und Eigenschaften von Silber- und Kaliumsalzen der Imido-diselensäure werden beschrieben; Infrarot-Spektren sowieDebye-Scherrer-Diagramme dieser erstmalig dargestellten Verbindungen werden zu ihrer Charakterisierung mitgeteilt.Mit 2 Abbildungen 相似文献
50.
Marković S Marković Z Engelbrecht JP McCrindle RI 《Journal of chemical information and computer sciences》2002,42(1):82-86
The relationship between the rate of supercritical fluid extraction of polycyclic aromatic hydrocarbons (PAHs) from coal-tar pitch and some topological invariants are examined. The aim is to explain the appearance of a minimum value on the activation energy/molar mass curve of the PAHs. Rate constants are approximated using spectral moment expansion. It is shown that the size of the PAHs determines more than 95% of the extraction rate. Activation energy for the extraction of the PAHs was found to increase with increasing molar mass. The appearance of a minimum value on the activation energy/molar mass curve is the consequence of experimental difficulties resulting from the tendency of lower members of the PAHs to sublime. 相似文献