全文获取类型
收费全文 | 397篇 |
免费 | 9篇 |
国内免费 | 4篇 |
专业分类
化学 | 230篇 |
力学 | 4篇 |
数学 | 103篇 |
物理学 | 73篇 |
出版年
2023年 | 1篇 |
2022年 | 21篇 |
2021年 | 18篇 |
2020年 | 9篇 |
2019年 | 6篇 |
2018年 | 8篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 8篇 |
2014年 | 20篇 |
2013年 | 37篇 |
2012年 | 27篇 |
2011年 | 30篇 |
2010年 | 17篇 |
2009年 | 16篇 |
2008年 | 31篇 |
2007年 | 22篇 |
2006年 | 17篇 |
2005年 | 14篇 |
2004年 | 12篇 |
2003年 | 16篇 |
2002年 | 9篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1991年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有410条查询结果,搜索用时 31 毫秒
121.
Adsorption of I2 by Macrocyclic Polyazadithiophenolato Complexes Mediated by Charge‐Transfer Interactions
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Matthias Golecki Norman Beyer Dr. Gunther Steinfeld Dr. Vasile Lozan Dr. Sergei Voitekhovich Dr. Muhamed Sehabi Dr. Jens Möllmer Prof. Dr. Hans‐Jörg Krüger Prof. Dr. Berthold Kersting 《Angewandte Chemie (International ed. in English)》2014,53(37):9949-9952
The macrocyclic complex [Ni2(L)(OAc)]ClO4 ( 1 ) adsorbs up to 17 molar equivalents (>270 wt %) of iodine, although it does not exhibit permanent porosity. Vibrational spectroscopic and crystallographic studies reveal that two I2 molecules are captured by means of thiophenolate→I2 charge‐transfer interactions, which enable the diffusion and sorption of further I2 molecules in a polyiodide‐like network. The efficient sorption and desorption characteristics make this material suitable for accommodation, sensing, and slow release of I2. 相似文献
122.
The purpose of this paper is to show how to use the Optimal Homotopy Asymptotic Method (OHAM) to solve the nonlinear differential Thomas-Fermi equation. Our procedure does not depend upon small parameters and provides us with a convenient way to optimally control the convergence of the approximate solutions. An excellent agreement was found between our approximate results and numerical solutions, which prove that OHAM is very efficient in practice, ensuring a very rapid convergence after only one iteration. 相似文献
123.
Carlo Andrea Massa Silvia Pizzanelli Vasile Bercu Luca Pardi Monica Bertoldo Dino Leporini 《Applied magnetic resonance》2014,45(7):693-706
The reorientation of a small paramagnetic tracer in poly(dimethylsiloxane) (PDMS) has been investigated by high-field electron paramagnetic resonance spectroscopy at a Larmor frequency of 285 GHz. The tracer is confined in the disordered phase of the semicrystalline PDMS. A sudden change of the rotational dynamics is observed close to the melting point (213 K) of the crystallites. This points to strong coupling between the crystalline and the disordered fractions of PDMS. Below the glass transition ( \(T_\mathrm{g} \sim 150 \mathrm{K}\) ), the tracer reorientation occurs via small angle jumps, with no apparent distribution of the correlation times. Above \(T_\mathrm{g}\) , a power-law distribution of correlation times is evidenced. 相似文献
124.
Vasile A. Popescu Niculae Tiberiu Puscas Guido Perrone 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2014,68(8):1-8
We report experimental research of the laser-produced indium plasma in hydrogen, argon and residual atmospheric ambient conditions. Note on general plasma behavior and morphology is presented. On the basis of intensity ratio of the two intense neutral resonance spectral lines (In I 410.2 nm and 451.1 nm), self-absorption was found to be almost negligible in case of argon environment at a pressure of 6650 Pa. Under these conditions, the first Stark widths (W) and shifts (d) measurements were performed as well. The resulting synthetic Lorentz profiles, based on the hyperfine structure of these two lines and corresponded W values, were calculated in order to reproduce measured W m in case of particular electron temperature (T) and number density (N). These results should be of interest to the upcoming theoretical calculations concerning neutral indium spectral lines and also for various diagnostic applications. 相似文献
125.
Dan Donescu Raluca Somoghi Catalin Ilie Spataru Doina Manaila-Maximean Denis Mihaela Panaitescu Eugeniu Vasile Cristina L. Nistor 《Colloid and polymer science》2013,291(10):2345-2358
The work describes a study for preparing polystyrene (PSt) and polymethyl methacrylate (PMMA) latex, containing magnetite (Fe3O4), covalently bounded to the polymeric chains. The magnetite was functionalized with various alkoxysilanes containing double bonds: vinyltriethoxysilane (VTES), methacryloyl propyl trimethoxysilane (MPTS) and vinyldimethylethoxysilane (VMe2TES). The ferrite-silane composite forms higher average size particles with MPTS than with VTES. Ferrite functionalized with VMe2TES forms stable latexes with both PSt and PMMA polymers. PSt forms also stable latexes with ferrite functionalized with VTES but unstable with ferrite functionalized with MPTS. 相似文献
126.
Gina Vasile Rodica Olar Dana Marinescu Angela Kriza Luminita Marutescu Mariana Carmen Chifiriuc Veronica Lazar Mihaela Badea 《Journal of Thermal Analysis and Calorimetry》2013,111(3):1783-1790
Five new coordinative compounds that contain mixed ligands (4,4′-bipyridine and methacrylate anion) were synthesized and characterized (elemental analysis, IR and UV–Vis spectroscopy, and thermal studies). The complexes are of the type [M(4,4′-bipy)(C4H5O2)2]·nH2O ((1) M:Mn, n = 0; (2) Co, n = 0.5; (3) M:Ni, n = 1.5; (4) M:Cu, n = 0.5; (5) M:Zn, n = 0.5; 4,4′-bipy: 4,4′-bipyridine; C4H5O2: methacrylate anion). All the tested complexes exhibited very low MIC values against Escherichia coli strains and one compound against Staphylococcus aureus. Besides the specific antimicrobial spectrum, these compounds also inhibited the microbial ability to colonize the inert surfaces, acting as potential anti-adherence and biofilm-controlling agents. The thermal behavior provided confirmation of the complexes' compositions as well as the number and the nature of water molecules and the intervals of thermal stability. 相似文献
127.
Miron Teodor Căproiu Florea Dumitrascu Sergiu Shova Ileana Cornelia Chirită Alexandru Vasile Missir Dana-Mihaela Cioroianu 《Tetrahedron letters》2014
New S-thiocarbamates possessing a 10,11-dihydro-5H-dibenzo[a,d]cycloheptene moiety were obtained unexpectedly in the process of preparing new O-thiocarbamates starting from 5-dibenzosuberol (10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-ol) and aroyl-isothiocyanates. These compounds were obtained via a benzylic Newman–Kwart rearrangement mechanism. The structures of the new thiocarbamates were confirmed by elemental analysis, IR, and NMR spectroscopy and by X-ray crystallography. 相似文献
128.
The aim of this paper is to introduce a new approximate method, namely the Optimal Parametric Iteration Method (OPIM) to provide
an analytical approximate solution to Thomas-Fermi equation. This new iteration approach provides us with a convenient way
to optimally control the convergence of the approximate solution. A good agreement between the obtained solution and some
well-known results has been demonstrated. The proposed technique can be easily applied to handle other strongly nonlinear
problems. 相似文献
129.
Marin Cernea Mihail Secu Corina Elisabeta Secu Mihaela Baibarac Bogdan S. Vasile 《Journal of nanoparticle research》2011,13(1):77-85
In this study, we report on the nanocrystalline powders of TiO2 and Fe-doped TiO2 (anatase and rutile phases) prepared by sol–gel method. The X-ray diffraction and Raman spectroscopy measurements indicated
the presence of anatase or rutile phase in nanopowders. TEM micrographs showed 10 and 112 nm average particle sizes for anatase
and rutile, respectively. Furthermore, their thermoluminescence properties were analyzed. 相似文献
130.
Cristina Ileana Covaliu Daniela Berger Cristian Matei Lucian Diamandescu Eugeniu Vasile Camelia Cristea Valentin Ionita Horia Iovu 《Journal of nanoparticle research》2011,13(11):6169-6180
This study reports a two-steps route for obtaining magnetic nanoparticles–polysaccharide hybrid materials consisting of Fe3O4, NiFe2O4 and CuFe2O4 nanoparticles synthesis by coprecipitation method in the presence of a soft template followed by coating of ferrite nanoparticles of 8–10-nm size range with polysaccharide type polymers—sodium alginate or chitosan. Magnetic oxide nanoparticles and the corresponding hybrid materials were characterized by X-ray diffraction (XRD), Mössbauer spectroscopy, atomic absorption spectroscopy (AAS), FTIR spectroscopy, scanning and transmission electron microscopy (SEM and TEM) and specific surface area measurements. The vibrating sample magnetometry confirms the superparamagnetic properties of the synthesized ferrites and hybrids. Using this route, the percent of magnetic nanoparticles retained in chitosan-based hybrid materials is nearly double in comparison with that of sodium alginate–based materials. The biological activity tests on Escherichia coli ATCC 25922, Pseudomonas aeroginosa ATCC 27853, Staphylococcus aureus ATCC 25923 and Candida scotti microorganisms show the non-toxic properties of prepared hybrid materials. 相似文献