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51.
Petar Kassal Robert Šurina Domagoj Vrsaljko Ivana Murković Steinberg 《Journal of Sol-Gel Science and Technology》2014,69(3):586-595
Optical sensors for application in innovative wearable sensing systems such as textile-integrated systems and wireless sensor platforms rely on the development of low-cost multifunctional materials compatible with standard fabrication technologies. We are developing optically responsive pH sensitive sol–gel coatings for integration with a mobile wireless smart tag sensing system. For this application, we have fabricated a range of thin pH sensitive films using bromocresol green (BCG) indicator immobilised in inorganic–organic silica hybrid matrices prepared by a sol–gel method and deposited by spin-coating onto glass substrates. The surface hydrophilicity of the films were varied by using the inorganic sol–gel precursor tetraethoxysilane together with either methyltriethoxysilane, ethyltriethoxysilane, phenyltrimethoxysilane or glycidoxypropyltrimethoxysilane as organically modified sol–gel precursors, co-polymerised in different ratios. Spectral characterisation of the films was performed using visible absorption spectroscopy. The shift in absorption maxima and other spectral changes of the different matrices have been identified, and the apparent pK app values of the immobilised BCG pH indicator determined. The surface wettability properties of the films have been studied by measuring the contact angle of water, formamide and diiodomethane which has allowed the estimation of the surface free energy (SFE) using three different models: Owens–Wendt, Wu and van Oss-Chaudhury-Good. It is shown that the SFE of the hybrid films is directly related to the type and the degree of organic modification, which in turn has a significant effect on the pH response-time of these sensing films. 相似文献
52.
Synthesis and Catalytic Use of Gold(I) Complexes Containing a Hemilabile Phosphanylferrocene Nitrile Donor 下载免费PDF全文
Karel Škoch Dr. Ivana Císařová Prof. Dr. Petr Štěpnička 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(45):15998-16004
Removal of the chloride ligand from [AuCl( 1 ‐κP)] ( 2 ) containing a P‐monodentate 1′‐(diphenylphosphanyl)‐1‐cyanoferrocene ligand ( 1 ), by using silver(I) salts affords cationic complexes of the type [Au( 1 )]X, which exist either as cyclic dimers [Au( 1 )]2X2 ( 3 a , X=SbF6; 3 c , X=NTf2) or linear coordination polymers [Au( 1 )]nXn ( 3 a′ , X=SbF6; 3 b′ , X=ClO4), depending on anion X and the isolation procedure. As demonstrated for 3 a′ , the polymers can be readily cleaved by the addition of donors, such as Cl?, tetrahydrothiophene (tht) or 1 , giving rise to the parent compound 2 , [Au(tht)( 1 ‐κP)][SbF6] ( 5 a ) or [Au( 1 ‐κP)2][SbF6] ( 4 a ), respectively, of which the last two compounds can also be prepared by stepwise replacement of tht in [Au( 1 ‐κP)2][SbF6]. The particular combination of a firmly coordinated (phosphane) and a dissociable (nitrile) donor moieties renders complexes 3/3′ attractive for catalysis because they can serve as shelf‐stable precursors of coordinatively unsaturated AuI fragments, analogous to those that result from the widely used [Au(PR3)(RCN)]X catalysts. The catalytic properties of the Au‐ 1 complexes were evaluated in model annulation reactions, such as the synthesis of 2,3‐dimethylfuran from (Z)‐3‐methylpent‐2‐en‐4‐yn‐1‐ol and oxidative cyclisation of alkynes with nitriles to produce 2,5‐disubstituted 1,3‐oxazoles. Of the compounds tested ( 2 , 3 a′ , 3 b′ , 3 a , 4 a and 5 a ), the best results were consistently achieved with dimer 3 c , which has good solubility in organic solvents and only one firmly bound donor at the gold atom. This compound was advantageously used in the key steps of annuloline and rosefuran syntheses. 相似文献
53.
Ivana Defrenza Alessia Catalano Alessia Carocci Antonio Carrieri Marilena Muraglia Antonio Rosato Filomena Corbo Carlo Franchini 《Journal of heterocyclic chemistry》2015,52(6):1705-1712
Starting from 2‐amino‐1,3‐mercaptobenzothiazoles recently reported ( 1a , 1b , 1c , 1d , 1e , 1f , 1g , 1h ), a series of the corresponding 2‐mercapto‐1,3‐benzothiazole isosters ( 2a , 2b , 2c , 2d , 2e , 2f , 2g , 2h ) were screened for their in vitro antibacterial and antifungal activities. Results underline that the presence of the mercapto moiety at the 2‐position of the heterocyclic nucleus is crucial for activity against bacteria. The biological screening against Candida spp. identified commercial 2f as the most promising compound as antifungal against Candida albicans and tropicalis. Molecular modeling studies supported these results. Then, to enlarge structure‐activity relationship (SAR) studies on series 1 , newly synthesized compounds ( 1k , 1l , 1m , 1n , 1o , 1p ) were reported. All the compounds belonging to this series and bearing a bulky substituent at the 6‐position of the aryl moiety showed high antifungal activity. 相似文献
54.
Separation and characterization of oxidized isomeric lipid–peptide adducts by ion mobility mass spectrometry 下载免费PDF全文
Ivana Milic Marc Kipping Ralf Hoffmann Maria Fedorova 《Journal of mass spectrometry : JMS》2015,50(12):1386-1392
Phospholipids are major components of cell membranes and lipoprotein complexes. They are prone to oxidation by endogenous and exogenous reactive oxygen species yielding a large variety of modified lipids including small aliphatic and phospholipid bound aldehydes and ketones. These carbonyls are strong electrophiles that can modify proteins and, thereby, alter their structures and functions triggering various pathophysiological conditions. The analysis of lipid–protein adducts by liquid chromatography‐MS is challenged by their mixed chemical nature (polar peptide and hydrophobic lipid), low abundance in biological samples, and formation of multiple isomers. Thus, we investigated traveling wave ion mobility mass spectrometry (TWIMS) to analyze lipid–peptide adducts generated by incubating model peptides corresponding to the amphipathic β1 sheet sequence of apolipoprotein B‐100 with 1‐palmitoyl‐2‐(oxo‐nonanoyl)‐sn‐glycerophosphatidylcholine (PONPC). The complex mixture of peptides, lipids, and peptide–lipid adducts was separated by TWIMS, which was especially important for the identification of two mono‐PONPC‐peptide isomers containing Schiff bases at different lysine residues. Moreover, TWIMS separated structural conformers of one peptide–lipid adduct possessing most likely different orientations of the hydrophobic sn‐1 fatty acyl residue and head group of PONPC, relative to the peptide backbone. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
55.
Single‐Crystal‐to‐Single‐Crystal Transition in an Enantiopure [7]Helquat Salt: The First Observation of a Reversible Phase Transition in a Helicene‐Like Compound 下载免费PDF全文
Dr. Naba K. Nath Lukáš Severa Dr. Roman A. Kunetskiy Prof. Ivana Císařová Prof. Michal Fulem Prof. Květoslav Růžička Dr. Dušan Koval Dr. Václav Kašička Dr. Filip Teplý Prof. Panče Naumov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(39):13508-13512
Here it is reported that crystals of an enantiopure [7]helquat salt undergo reversible thermal solid–solid phase transition at 404 K. Differential scanning calorimetry (DSC), capillary electrophoresis (CE), and X‐ray diffraction analysis were used to unravel the mechanistic details of this process. The single‐crystal‐to‐single‐crystal course enabled direct monitoring of the structural changes by in situ variable‐temperature X‐ray diffraction, thus providing the first direct evidence of a solid phase transition in a helicene‐like compound. 相似文献
56.
Highly Functionalized Cyclopentane Derivatives by Tandem Michael Addition/Radical Cyclization/Oxygenation Reactions 下载免费PDF全文
Ing. Martin Holan Dr. Radek Pohl Dr. Ivana Císařová Dr. Blanka Klepetářová Prof. Dr. Peter G. Jones Dr. Ullrich Jahn 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9877-9888
Densely functionalized cyclopentane derivatives with up to four consecutive stereocenters are assembled by a tandem Michael addition/single‐electron transfer oxidation/radical cyclization/oxygenation strategy mediated by ferrocenium hexafluorophosphate, a recyclable, less toxic single‐electron transfer oxidant. Ester enolates were coupled with α‐benzylidene and α‐alkylidene β‐dicarbonyl compounds with switchable diastereoselectivity. This pivotal steering element subsequently controls the diastereoselectivity of the radical cyclization step. The substitution pattern of the radical cyclization acceptor enables a switch of the cyclization mode from a 5‐exo pattern for terminally substituted olefin units to a 6‐endo mode for internally substituted acceptors. The oxidative anionic/radical strategy also allows efficient termination by oxygenation with the free radical 2,2,6,6‐tetramethyl‐1‐piperidinoxyl, and two C?C bonds and one C?O bond are thus formed in the sequence. A stereochemical model is proposed that accounts for all of the experimental results and allows the prediction of the stereochemical outcome. Further transformations of the synthesized cyclopentanes are reported. 相似文献
57.
Andreu Presa Rosa F. Brissos Ana Belén Caballero Ivana Borilovic Dr. Luís Korrodi‐Gregório Prof. Ricardo Pérez‐Tomás Dr. Olivier Roubeau Prof. Patrick Gamez 《Angewandte Chemie (International ed. in English)》2015,54(15):4561-4565
The photoactivation of potential anticancer metal complexes is a hot topic of current research as it may lead to the development of more selective drugs. Photoactivated chemotherapy (PACT) with coordination compounds is usually based on a (photo)chemical reaction taking place at the metal center. Herein, a new strategy is exploited that consists of “photomodifying” a ligand coordinated to metal ions. Platinum(II) complexes from photoswitchable 1,2‐dithienylethene‐containing ligands have been prepared, which exhibit two interconvertible photoisomeric forms that present distinct DNA‐interacting properties and cytotoxic behaviors. 相似文献
58.
Jarmila Duskova Jiri Labsky Ivana Cisarova Tereza Skalova Jan Dohnalek Jindrich Hasek 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(9):o563-o566
The asymmetric unit of the title compound, C11H5D16N2O2·0.33H2O, is formed by three crystallographically independent piperidin‐1‐yloxyl molecules and a molecule of water. The molecules are crosslinked by nine hydrogen bonds into layers parallel with the ac plane. The water molecule contributes to the stability of the low‐symmetry arrangement by four hydrogen bonds. 相似文献
59.
Ivana Brekalo David E. Deliz Leonard J. Barbour Michael D. Ward Tomislav Fri
i K. Travis Holman 《Angewandte Chemie (International ed. in English)》2020,59(5):1997-2002
Guanidinium organosulfonates (GSs) are a large and well‐explored archetypal family of hydrogen‐bonded organic host frameworks that have, over the past 25 years, been regarded as nonporous. Reported here is the only example to date of a conventionally microporous GS host phase, namely guanidinium 1,4‐benzenedisulfonate ( p ‐G2BDS ). p ‐G2BDS is obtained from its acetone solvate, AcMe@ G2BDS , by single‐crystal‐to‐single‐crystal (SC‐SC) desolvation, and exhibits a Type I low‐temperature/pressure N2 sorption isotherm (SABET=408.7(2) m2 g?1, 77 K). SC‐SC sorption of N2, CO2, Xe, and AcMe by p ‐G2BDS is explored under various conditions and X‐ray diffraction provides a measurement of the high‐pressure, room temperature Xe and CO2 sorption isotherms. Though p ‐G2BDS is formally metastable relative to the “collapsed”, nonporous polymorph, np ‐G2BDS , a sample of p ‐G2BDS survived for almost two decades under ambient conditions. np ‐G2BDS reverts to zCO2@ p ‐G2BDS or yXe@ p ‐G2BDS (y,z=variable) when pressure of CO2 or Xe, respectively, is applied. 相似文献
60.
Veronika Barii Milica Cvijeti Stokanovi Ivana Flanjak Kristina Doko Antun Jozinovi Jurislav Babi Drago ubari Borislav Mili
evi Ines Cindri urica A
kar 《Molecules (Basel, Switzerland)》2020,25(22)
Chocolate is considered as both caloric and functional food. Its nutritional properties may be improved by addition of fiber; however, this may reduce polyphenols content. The aim of this research was to determine the influence of cocoa shell addition (as a source of fiber) and its combination with different ingredients (cocoa butter equivalents (CBE), emulsifiers, dairy ingredients) on polyphenols of dark and milk chocolates. Total polyphenol (TPC) and total flavonoid (TFC) contents were determined spectrophotometrically, identification and quantification of individual compounds by high pressure liquid chromatography and antioxidant capacity by ferric reducing antioxidant power (FRAP) assay. Results showed that even though addition of cocoa shell to chocolate results in reduced contents of TPC, TFC, and individual compounds, it is not significant compared to ones reported by other authors for commercial chocolates. Other ingredients influence determined values for all investigated parameters; however, additional research is needed to reveal exact mechanisms and implications. 相似文献