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131.
Zoran Andelkovic Gerhard Birkl Svetlana Fedotova Volker Hannen Frank Herfurth Kristian König Nikita Kotovskiy Bernhard Maaß Jonas Vollbrecht Tobias Murböck Dennis Neidherr Wilfried Nörtershäuser Stefan Schmidt Manuel Vogel Gleb Vorobjev Christian Weinheimer 《Hyperfine Interactions》2015,231(1-3):37-44
Heavy few-electron ions are relatively simple systems in terms of electron structure and offer unique opportunities to conduct experiments under extremely large electromagnetic fields that exist around their nuclei. However, the preparation of highly charged ions (HCI) has remained the major challenge for experiments. As an extension of the existing GSI accelerator facility, the HITRAP facility was conceived as a multi-stage decelerator for HCI produced at high velocity. It is designed to prepare bunches of around 105 HCI and to deliver them at low energies to various experiments. One of these experiments is SpecTrap, aiming for laser spectroscopy of trapped, cold HCI. We present the latest results on deceleration of ions in a radio-frequency quadrupole, synchrotron cooling of electrons in a trap as a preparation step for the prospective electron cooling of the HCI decelerated in HITRAP, as well as laser cooling of singly charged Mg ions for sympathetic cooling of HCI in SpecTrap. 相似文献
132.
Konstantin L. Ivanov Dmitri V. Stass Evgeny V. Kalneus Robert Kaptein Nikita N. Lukzen 《Applied magnetic resonance》2013,44(1-2):217-232
In this work we have compared manifestations of degenerate electron exchange (DEE) and dimerization reactions in MARY (magnetically affected reaction yield) spectroscopy and time-resolved magnetic field effects (TR-MFE) of radical ion pairs (RIPs). It is shown that dimerization results in phase and frequency changes of the quantum beats in TR-MFE traces, whereas DEE leads to relaxation-type changes in the spin dynamics of RIPs. Dimerization does not change the width of MARY lines considerably, but leads to new lines corresponding to dimer radical ions. In contrast, DEE substantially changes the MARY line widths. Our treatment provides ways to discriminate between both processes from experimental MARY spectra and TR-MFE kinetics. An experimental example dealing with concentration-dependent broadening of the MARY lines is also discussed. 相似文献
133.
Seylan Ayan Özdemir Dogan Polina M. Ivantcova Nikita G. Datsuk Dmitry A. Shulga Vladimir I. Chupakhin Dmitry V. Zabolotnev Konstantin V. Kudryavtsev 《Tetrahedron: Asymmetry》2013,24(13-14):838-843
The (2R,4R,5S)- and (2S,4S,5R)-enantiomers of 4-(tert-butyl) 2-methyl 5-(4-bromophenyl)-pyrrolidine-2,4-dicarboxylate 3 were synthesized efficiently with an ee of >90% on a gram scale using a FAM-catalytic methodology. Subsequent modification afforded enantiopure N-((4-chlorophenyl)thio)acetyl pyrrolidine derivatives 4, which are potential thrombin inhibitors according to comprehensive molecular docking studies. 相似文献
134.
Liudmila Kulakova Vladislav Gorelov Andrey Lutetskiy Nikita S. Averkiev 《Solid State Communications》2012,152(17):1690-1693
The paper is devoted to an acousto-electron effect in the nanodimensional laser heterostructures. The effect results in a modulation of the laser emission intensity as well as in a turn of the emission polarization by the sound strain. Theoretical treatment of the experimental data is presented. 相似文献
135.
Let \(T:[0,1]\rightarrow [0,1]\) be the doubling map and let \(0 . We say that an integer \(n\ge 3\) is bad for \((a,b)\) if all \(n\) -cycles for \(T\) intersect \((a,b)\) . Let \(B(a,b)\) denote the set of all \(n\) which are bad for \((a,b)\) . In this paper we completely describe the sets: $$\begin{aligned} D_2=\{(a,b) : B(a,b)\,\text {is finite}\} \end{aligned}$$ and $$\begin{aligned} D_3=\{(a,b) : B(a,b)=\varnothing \}. \end{aligned}$$ In particular, we show that if \(b-a<\frac{1}{6}\) , then \((a,b)\in D_2\) , and if \(b-a\le \frac{2}{15}\) , then \((a,b)\in D_3\) , both constants being sharp. 相似文献
136.
О,О‐Dialkyl‐S‐(1,1‐dimethyl‐2‐oxoethyl)dithiophosphates: Synthesis and Reactions with n‐Nucleophiles
Mukattis B. Gazizov Rafail A. Khairullin Nikita G. Aksenov Oleg G. Sinyashin 《Heteroatom Chemistry》2015,26(6):436-440
Hydrolysis of the new types of iminium salts was used to synthesize О,О‐dialkyl‐S‐(1,1‐dimethyl‐2‐oxoethyl)dithiophosphates or 2‐dialkoxythiophosphorylthio‐substituted aldehydes with carbon isochain. Reactions of aldehydes with N‐, N,N‐, and O,N‐nucleophiles gave new phosphorylated imines containing an acetal group at different positions, perhydro‐1,3‐diazol and oxazol with the diisopropoxythiophosphorylthio group in a side chain, and hydrazone of this aldehyde and diphenylphosphinylacetic acid hydrazide. 相似文献
137.
138.
It is known (yet often ignored) from quantum mechanical or energetic considerations, that the threshold gain of the quasi‐static spaser depends only on the dielectric functions of the metal and the gain material. Here, we derive this result from the purely classical electromagnetic scattering framework. This is of great importance, because electrodynamic modelling is far simpler than quantum mechanical one. The influence of the material dispersion and spaser geometry are clearly separated; the latter influences the threshold gain only indirectly, defining the resonant wavelength. We show that the threshold gain has a minimum as a function of wavelength. A variation of nanoparticle shape, composition, or spasing mode may shift the plasmonic resonance to this optimal wavelength, but it cannot overcome the material‐imposed minimal gain. Furthermore, retardation is included straightforwardly into our framework; and the global spectral gain minimum persists beyond the quasi‐static limit. We illustrate this with two examples of widely used geometries: Silver spheroids and spherical shells embedded in and filled with gain materials. 相似文献
139.
Chemometrics assisted spectrophotometric determination of pyridine in water and wastewater 总被引:1,自引:0,他引:1
The paper reports a direct method for the determination of pyridine in water and wastewater samples based on ultraviolet spectrophotometric measurements using multi-way modeling techniques. Parallel factor analysis (PARAFAC) and multi-way partial least squares (N-PLS) regression methods were employed for the decomposition of spectra and quantification of pyridine. The study was carried out in the pH range of 1.0-12.0 and concentration range of 0.67-51.7 μg mL−1 of pyridine. Both the three-way PARAFAC and tri-PLS1 models successfully predicted the concentration of pyridine in synthetic (spiked) river water and field wastewater samples. The mean recovery obtained from PARAFAC regression model were 97.39% for the spiked and 99.84% for the field wastewater samples, respectively. The sensitivity and precision of the method for pyridine determination were 0.58% and 5.95%, respectively. The N-PLS regression model yielded mean recoveries of 99.29% and 100.18% for the spiked and field wastewater samples, respectively. The prediction accuracy of the methods was evaluated through the root mean square error of prediction (RMSEP). For PARAFAC, it was 0.65 and 0.82 μg mL−1 for spiked river water and field wastewater samples, respectively, while for N-PLS, it was 0.25 and 0.37 μg mL−1, respectively. Both the PARAFAC and N-PLS methods, thus, yielded satisfactory results for the prediction of pyridine concentration in water and wastewater samples. 相似文献
140.
Vera V. Voinova Nikita A. Selivanov Ivan V. Plyushchenko Mikhail F. Vokuev Alexander Yu. Bykov Ilya N. Klyukin Alexander S. Novikov Andrey P. Zhdanov Mikhail S. Grigoriev Igor A. Rodin Konstantin Yu. Zhizhin Nikolay T. Kuznetsov 《Molecules (Basel, Switzerland)》2021,26(1)
The novel members of the 1,2-diboraoxazoles family have been obtained. In the present work, we have carried out the intramolecular ring-closure reaction of borylated iminols of general type [B10H9N=C(OH)R]− (R = Me, Et, nPr, iPr, tBu, Ph, 4-Cl-Ph). This process is conducted in mild conditions with 83–87% yields. The solid-state structures of two salts of 1,2-diboraoxazoles were additionally investigated by X-ray crystallography. In addition, the phenomena of bonding interactions in the 1,2-diboraoxazole cycles have been theoretically studied by the Quantum Theory of Atoms in Molecules analysis. Several local and integral topological properties of the electron density involved in these interactions have been computed. 相似文献