全文获取类型
收费全文 | 171篇 |
免费 | 1篇 |
专业分类
化学 | 121篇 |
晶体学 | 1篇 |
力学 | 2篇 |
数学 | 30篇 |
物理学 | 18篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 9篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 8篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 7篇 |
2012年 | 16篇 |
2011年 | 9篇 |
2010年 | 17篇 |
2009年 | 7篇 |
2008年 | 10篇 |
2007年 | 17篇 |
2006年 | 6篇 |
2005年 | 5篇 |
2004年 | 8篇 |
2003年 | 2篇 |
2002年 | 10篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1993年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
排序方式: 共有172条查询结果,搜索用时 265 毫秒
61.
It is shown the complete equivalence between the theory of continuous (enumeration) fuzzy closure operators and the theory
of (effective) fuzzy deduction systems in Hilbert style. Moreover, it is proven that any truth-functional semantics whose
connectives are interpreted in [0,1] by continuous functions is axiomatizable by a fuzzy deduction system (but not by an effective
fuzzy deduction system, in general).
Received: 15 February 2001 / Revised version: 31 May 2001 / Published online: 12 July 2002 相似文献
62.
Loredana Bellantuono 《Few-Body Systems》2016,57(8):717-722
The mass spectrum of the gluonium with \({J^{PC}=0^{--}}\) is examined in three bottom-up AdS/QCD models. The results are used to identify several production and decay modes useful for searching this state. Moreover, the properties of such glueball in a hot and dense quark medium are discussed. 相似文献
63.
Latterini L Nocchetti M Aloisi GG Costantino U De Schryver FC Elisei F 《Langmuir : the ACS journal of surfaces and colloids》2007,23(24):12337-12343
ZnAl hydrotalcites containing increasing amounts of 9-anthracenecarboxylate anion (9AC) have been obtained via an anion-exchange procedure. In particular, intercalated and/or surface-exchanged samples were prepared to study the effect of the chromophore packing on their photophysical and photochemical behavior. Surface-exchanged samples were obtained by equilibrating the carbonate form of the ZnAl hydrotalcite with dilute solutions of 9AC. The nitrate form of the ZnAl hydrotalcite was instead chosen for the preparation of intercalation compounds. The maximum loading of 9AC was found to be 44% of the anion-exchange capacity. The obtained nanostructured materials were characterized by chemical and thermal analysis and X-ray powder diffractometry and studied for their photophysical and photochemical properties. The absorption and emission spectra of the materials revealed the formation of 9AC aggregates. The time-resolved fluorescence properties of the hybrid materials were investigated in bulk and under space-resolved conditions. The fluorescence decays appeared to be quite complex and were affected by the microenvironment and the experimental conditions. Generally, a shortening of the main fluorescence decay component was observed with increasing matrix loading, thus suggesting the occurrence of nonradiative processes in competition with fluorescence at high chromophore concentrations. Indeed, the occurrence of an electron-transfer process to water molecules, which led to the formation of 9AC radical, was observed spectrophotometrically in the sample with high 9AC loading. The electron-transfer process was completely reversible under air-equilibrated conditions. 相似文献
64.
The purpose of this paper is to complement the results by Lanzani and Stein(2017) by showing the dense definability of the Cauchy-Leray transform for the domains that give the counter-examples of Lanzani and Stein(2017), where L~p-boundedness is shown to fail when either the "near" C~2 boundary regularity, or the strong C-linear convexity assumption is dropped. 相似文献
65.
66.
Preda L Negrila C Lazarescu MF Anastasescu M Dobrescu G Santos E Lazarescu V 《Physical chemistry chemical physics : PCCP》2011,13(38):17104-17114
Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) investigations on the redox behavior of hemin at bare and 4,4'-thio-bis-benzene-thiolate (TBBT) covered n-GaAs (110) electrodes in dimethylsulfoxide (DMSO) revealed the high irreversibility of the electroreduction process, which appeared to be closely related to the stable adsorbed species strongly interfering with the electronic properties of the semiconducting substrate. The subsequent exploration of the hemin-modified electrodes by second harmonic generation (SHG), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) measurements pointed to significant differences between the iron protoporphyrin species adsorbed on the bare- and TBBT-GaAs (110) electrodes. Only Fe(2+) species having a flat configuration with the porphyrin plane oriented parallel to the surface were detected on GaAs, unlike the TBBT-GaAs, where Fe(2+) and Fe(3+) species having both flat and vertical adsorption positions could be observed. These differences originate from the mutual interactions between the solvent, hemin and dithiolate molecules as well as their competition for the surface sites found to play a key role in the electrochemical process under discussion. 相似文献
67.
Erra L Tedesco C Immediata I Gregoli L Gaeta C Merlini M Meneghini C Brunelli M Fitch AN Neri P 《Langmuir : the ACS journal of surfaces and colloids》2012,28(22):8511-8517
The inclusion properties of a calixarene-based porous material have been studied to investigate the adsorption and the desorption of carbon tetrachloride, chloroform, and water in the zeolite-like structure. Uptake and release processes have been studied both by time-resolved powder X-ray diffraction and by thermogravimetric analysis to obtain structural and kinetic information. The selected guests are able to enter the structure with an increase in the host cell volume and with time-dependent diffusivity coefficients. Chloroform molecules act as a permanent porosity switch promoting a phase transition to non-porous triclinic form. 相似文献
68.
L Ricciardi F Puoci G Cirillo M La Deda 《Dalton transactions (Cambridge, England : 2003)》2012,41(36):10923-10925
The grafting of a 2-picolylamine Pt(ii) complex into polymethacrylic acid has been successfully performed. The obtained polymer is water soluble, and it represents the first example of a platinum-containing polymer able to photogenerate singlet oxygen. 相似文献
69.
Loredana Biacino 《Rendiconti del Circolo Matematico di Palermo》2009,58(2):311-317
In questa breve nota si dimostra una condizione necessaria che deve essere soddisfatta nei punti di un sottoinsieme denso
del suo insieme di definizione da una funzione reale continua di cui sia nota la dimensione frattale del diagramma.
相似文献
70.
Sigolène Canaguier Loredana Vaccaro Dr. Vincent Artero Dr. Rainer Ostermann Jacques Pécaut Dr. Martin J. Field Dr. Marc Fontecave Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(37):9350-9364
The new dinuclear nickel–ruthenium complexes [Ni(xbsms)RuCp(L)][PF6] (H2xbsms=1,2‐bis(4‐mercapto‐3,3‐dimethyl‐2‐thiabutyl)benzene; Cp?=cyclopentadienyl; L=DMSO, CO, PPh3, and PCy3) are reported and are bioinspired mimics of NiFe hydrogenases. These compounds were characterized by X‐ray diffraction techniques and display novel structural motifs. Interestingly, [Ni(xbsms)RuCpCO][PF6] is stereochemically nonrigid in solution and an isomerization mechanism was derived with the help of density functional theory (DFT) calculations. Because of an increased electron density on the metal centers [Eur. J. Inorg. Chem. 2007 , 18 , 2613–2626] with respect to the previously described [Ni(xbsms)Ru(CO)2Cl2] and [Ni(xbsms)Ru(p‐cymene)Cl]+ complexes, [Ni(xbsms)RuCp(dmso)][PF6] catalyzes hydrogen evolution from Et3NH+ in DMF with an overpotential reduced by 180 mV and thus represents the most efficient NiFe hydrogenase functional mimic. DFT calculations were carried out with several methods to investigate the catalytic cycle and, coupled with electrochemical measurements, allowed a mechanism to be proposed. A terminal or bridging hydride derivative was identified as the active intermediate, with the structure of the bridging form similar to that of the Ni? C active state of NiFe hydrogenases. 相似文献