全文获取类型
收费全文 | 102篇 |
免费 | 0篇 |
专业分类
化学 | 60篇 |
力学 | 1篇 |
数学 | 13篇 |
物理学 | 28篇 |
出版年
2022年 | 4篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 5篇 |
2013年 | 2篇 |
2012年 | 2篇 |
2011年 | 6篇 |
2010年 | 3篇 |
2009年 | 1篇 |
2008年 | 6篇 |
2007年 | 6篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 1篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1968年 | 2篇 |
1967年 | 2篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1957年 | 1篇 |
1942年 | 2篇 |
1931年 | 2篇 |
1928年 | 3篇 |
1921年 | 1篇 |
排序方式: 共有102条查询结果,搜索用时 15 毫秒
31.
32.
Pl Perjsi Juha Linnanto Erkki Kolehmainen Erzsbet sz Elina Virtanen 《Journal of Molecular Structure》2005,740(1-3):81-89
Single substituent parameter (SSP) and dual substituent parameter (DSP) analyses were applied to study the transmission of substituent effects on selected 13C NMR chemical shifts of the cyclic chalcone analogues, E-2-(4′-X-benzylidene)-1-tetralones (2) and E-2-(4′-X-benzylidene)-1-benzosuberones (3). In order to study how the geometry of the cyclic chalcone analogues affects the transmission of substituent effects similar investigations with the respective chalcones (4) were also performed. The results obtained earlier with the five-membered analogue E-2-(4′-X-benzylidene)-1-indanones (1) were also involved in the comparisons. Geometry optimization of the unsubstituted 1a, 2a, 3a and 4a as well as the substituted 2 and 3 was performed by ab initio quantum chemical calculations. Both SSP and DSP analyses reflected that resonance effects contribute more to the chemical shift of C- (C2), while inductive effects primarily affect that of C-β (C10) of the enone moiety of all the four series. This latter effect, however, is far not as pronounced as that of the former one. It was found that DSP analysis data (ρF and ρR values) of transmission of substituent effects on the δC2 data can serve as a measure of choice to study the conformation (planarity) of the investigated enones in the four series. 相似文献
33.
Adina Arvinte Mika Mahosenaho Mariana Pinteala Adama-Marie Sesay Vesa Virtanen 《Mikrochimica acta》2011,174(3-4):337-343
The electrochemical oxidation of p-nitrophenol (p-NP) has been studied comparatively on a graphene modified electrode and a multiwall carbon nanotube (MWNT) electrode by using cyclic and differential pulse voltammetry. The sensors were fabricated by modifying screen-printed electrodes with graphene and MWNT nanomaterials, respectively, both dispersed in Nafion polymer. p-NP is irreversibly oxidized at +0.9?V (vs. the Ag/AgCl) in solutions of pH 7. The height and potential of the peaks depend on pH in the range from 5 to 11. In acidic media, p-NP yields a well-defined oxidation peak at +0.96?V which gradually increases in height with the concentration of the analyte. In case of differential pulse voltammetry in sulfuric acid solution, the sensitivity is practically the same for both electrodes. The modified electrodes display an unusually wide linear response (from 10???M to 0.62?mM of p-NP), with a detection limit of 0.6???M in case of the graphene electrode, and of 1.3???M in case of the MWNT electrode. Figure
DPV responses of graphene and MWNT electrodes to increasing concentrations of p-NP in H2SO4 20?mM solution. Inset: liniar plot of oxidation peak currents with the concentration of p-NP. 相似文献
34.
Artturi I. Virtanen 《Fresenius' Journal of Analytical Chemistry》1928,74(9):321-330
Ohne Zusammenfassung 相似文献
35.
M. Piiparinen A. Ataç G. de Angelis S. Forbes N. Gjørup G. Hageman B. Herskind F. Ingebretsen H. Jensen D. Jerrestam H. Kusakari R. Lieder G. M. Marti S. Mullins J. Nyberg A. Santonocito H. Schnare G. Sletten K. Strahle M. Sugawara P. O. Tjøm A. Virtanen R. Wadsworth 《Zeitschrift für Physik A Hadrons and Nuclei》1992,343(3):367-368
The level scheme of 143 Eu has been extended to I=75/2 in an experiment with the NORDBALL Compton-suppressed Ge detector array and the 110 Pd(37 Cl, 4n) reaction. Most of the scheme shows irregular structure of multiparticle excitations. A strongly populated straight cascade of more than 10 stretched E2 transitions suggests the onset of collectivity. 相似文献
36.
37.
P. Kivalo R. Virtanen K. Wickström M. Wilson E. Pungor G. Horvai K. Tóth 《Analytica chimica acta》1976,87(2):401-409
Two types of commercial lead(II)-selective electrode, the Orion 94-82 and the R??i?ka lead Selectrode, are compared. Calibration curves were determined in both buffered and unbuffered lead-ion solutions repeatedly for several weeks. Selectivities with respect to copper(II), silver(I), mercury(II), iron(III), zinc and cadmium were examined as well as the pH response by the mixed solution method. The response times of the electrodes were also studied. 相似文献
38.
A. Santasalo-Aarnio J. Virtanen M. Gasik 《Journal of Solid State Electrochemistry》2016,20(6):1655-1663
SO2-depolarized electrolysis (SDE) is considered as one of the most efficient hydrogen production methods. To maximize H2 production in SDE, the phenomena occurring in the cell need to be understood and controlled. In this work, electrochemically driven SO2 carry-over and elemental sulphur formation in cathode space are analysed by various methods: electrochemical, titration and photon correlation spectroscopy (PCS) under different conditions during SDE operation. The results indicate that SO2 carry-over is a fast process in an operating SDE and is difficult to control with only working parameter optimization. The PCS method provides SO2 carry-over information at early stages compared to other methods. Moreover, PCS might be further implemented as an in situ method for SDE system control. 相似文献
39.
Suvi Lehtimäki Sampo Tuukkanen Juho Pörhönen Pasi Moilanen Jorma Virtanen Mari Honkanen Donald Lupo 《Applied Physics A: Materials Science & Processing》2014,117(3):1329-1334
We report ecological and low-cost carbon nanotube (CNT) supercapacitors fabricated using a simple, scalable solution processing method, where the use of a highly porous and electrically conductive active material eliminates the need for a current collector. Electrodes were fabricated on a poly(ethylene terephthalate) substrate from a printable multi-wall CNT ink, where the CNTs are solubilized in water using xylan as a dispersion agent. The dispersion method facilitates a very high concentration of CNTs in the ink. Supercapacitors were assembled using a paper separator and an aqueous NaCl electrolyte and the devices were characterized with a galvanostatic discharge method defined by an industrial standard. The capacitance of the \(2\hbox { cm}^2\) devices was \(6\hbox { mF/cm}^2\) (2.3 F/g) and equivalent series resistance \(80\,\Omega \) . Low-cost supercapacitors fabricated from safe and environmentally friendly materials have potential applications as energy storage devices in ubiquitous and autonomous intelligence as well as in disposable low-end products. 相似文献
40.
The Fermi-liquid theory formulated by Landau is a basic paradigm of the behavior of an interacting many-body system. We present a new application of this theory to calculate the "Landau force" on a macroscopic object. We show that immersing a pendulum in a Fermi liquid can increase its oscillation frequency, and evidence of this has been observed in mixtures of (3)He and (4)He. 相似文献