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151.
Influence of the Homopolar Dihydrogen Bonding CH⋅⋅⋅HC on Coordination Geometry: Experimental and Theoretical Studies 下载免费PDF全文
Dr. Damir A. Safin Dr. Maria G. Babashkina Dr. Koen Robeyns Dr. Mariusz P. Mitoraj Dr. Piotr Kubisiak Prof. Yann Garcia 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(46):16679-16687
The reaction of the N‐thiophosphorylated thiourea (HOCH2)(Me)2CNHC(S)NHP(S)(OiPr)2 (HL), deprotonated by the thiophosphorylamide group, with NiCl2 leads to green needles of the pseudotetrahedral complex [Ni(L‐1,5‐S,S′)2] ? 0.5 (n‐C6H14) or pale green blocks of the trans square‐planar complex trans‐[Ni(L‐1,5‐S,S′)2]. The former complex is stabilized by homopolar dihydrogen C?H???H?C interactions formed by n‐hexane solvent molecules with the [Ni(L‐1,5‐S,S′)2] unit. Furthermore, the dispersion‐dominated C?H??? H?C interactions are, together with other noncovalent interactions (C?H???N, C?H???Ni, C?H???S), responsible for pseudotetrahedral coordination around the NiII center in [Ni(L ‐1,5‐S,S′)2] ? 0.5 (n‐C6H14). 相似文献
152.
Aqueous Self‐Assembly and Cation Selectivity of Cobaltabisdicarbollide Dianionic Dumbbells 下载免费PDF全文
Màrius Tarrés Prof. Clara Viñas Patricia González‐Cardoso Dr. Mikko M. Hänninen Prof. Reijo Sillanpää Vladimír Ďorďovič Dr. Mariusz Uchman Prof. Francesc Teixidor Dr. Pavel Matějíček 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(22):6786-6794
The anion [3,3′‐Co(C2B9H11)2]? ([COSAN]?) produces aggregates in water. These aggregates are interpreted to be the result of C?H???H?B interactions. It is possible to generate aggregates even after the incorporation of additional functional groups into the [COSAN]? units. The approach is to join two [COSAN]? anions by a linker that can adapt itself to act as a crown ether. The linker has been chosen to have six oxygen atoms, which is the ideal number for K+ selectivity in crown ethers. The linker binds the alkaline metal ions with different affinities; thus showing a distinct degree of selectivity. The highest affinity is shown towards K+ from a mixture containing Li+, Na+, K+, Rb+ and Cs+; this can be indicative of pseudo‐crown ether performance of the dumbbell. One interesting possibility is that the [COSAN]? anions at the two ends of the linker can act as a hook‐and‐loop fastener to close the ring. This facet is intriguing and deserves further consideration for possible applications. The distinct affinity towards alkaline metal ions is corroborated by solubility studies and isothermal calorimetry thermograms. Furthermore, cryoTEM micrographs, along with light scattering results, reveal the existence of small self‐assemblies and compact nanostructures ranging from spheres to single‐/multi‐layer vesicles in aqueous solutions. The studies reported herein show that these dumbbells can have different appearances, either as molecules or aggregates, in water or lipophilic phases; this offers a distinct model as drug carriers. 相似文献
153.
Paweł Szroeder Nikos G. Tsierkezos Mariusz Walczyk Włodzimierz Strupiński Agnieszka Górska-Pukownik Janusz Strzelecki Kamil Wiwatowski Peter Scharff Uwe Ritter 《Journal of Solid State Electrochemistry》2014,18(9):2555-2562
Electrocatalytic activity of graphene grown epitaxially on SiC is studied using cyclic voltammetry and electrochemical impedance spectroscopy. AFM images show step-like topography of SiC-graphene. For ferri-/ferrocyanide redox couple, no voltammetric response is observed at the pristine graphene. Basal planes of graphite are electrochemically inactive as well. After electrochemical oxidation, apparent redox peaks appear at both the graphene and graphite electrode. However, more intensive redox peaks are observed at graphene, where simultaneous redox reaction with the adsorbed and the diffused ferri-/ferrocyanide ions occurs. Electrochemical impedance measurements show that the graphene electrode behaves like an array of microelectrodes. We used the partially blocked electrode model to fit impedance data. Using the fitting parameters, a size of microelectrodes was found to be 23.8?±?2.1 μm and the active surface of graphene was estimated to be 21 %. A value of the standard electron transfer rate constant found for the anodized epitaxial graphene (2.16?±?0.32)?×?10??3cm???s??1) is by one order of magnitude lower than the standard rate constant estimated for the anodized graphite basal planes (~5?×?10??2cm???s??1). Electrochemical reduction causes total disappearance of electrochemical responses at the graphene electrode, whereas only slight decrease of the peak currents is observed at the reduced graphene. Such behavior proves that different activation mechanisms occur at the graphene and graphite electrodes. 相似文献
154.
155.
Mariusz Walkowiak Monika Osińska Teofil Jesionowski Katarzyna Siwińska-Stefańska 《Central European Journal of Chemistry》2010,8(6):1311-1317
This paper describes the synthesis and properties of a new type of ceramic fillers for composite polymer gel electrolytes.
Hybrid TiO2-SiO2 ceramic powders have been obtained by co-precipitation from titanium(IV) sulfate solution using sodium silicate as the precipitating
agent. The resulting submicron-size powders have been applied as fillers for composite polymer gel electrolytes for Li-ion
batteries based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF/HFP) copolymeric membranes. The powders, dry membranes
and gel electrolytes have been examined structurally and electrochemically, showing favorable properties in terms of electrolyte
uptake and electrochemical characteristics in Li-ion cells. 相似文献
156.
Mariusz Uchman Karel Proch��zka Katerina Gatsouli Stergios Pispas Milena ?p��rkov�� 《Colloid and polymer science》2011,289(9):1045-1053
Two samples of poly(sodium(sulfamate-carboxylate)isoprene)-block-poly(ethylene oxide) copolymer (SCIEO-1 and SCIEO-2) differing in molecular weight and relative length of polyelectrolyte blocks have been used as templates for the synthesis of cadmium sulfide (CdS) nanoparticles in aqueous media. The double-hydrophilic copolymer SCIEO has very high 1D charge density, and its polymer chain structure mimics that of polysaccharide heparin. It is soluble in aqueous media, but the addition of cadmium acetate (Cd(Ac)2) to its aqueous solution causes the formation of micellar aggregates with Cd2+containing insoluble cores above the threshold Cd2+ concentration. The trapped Cd2+ ions can be chemically transformed to CdS nanoparticles. The stability of hybrid SCIEO/CdS micelles depends on the ratio of PEO-to-SCI lengths: it was found that the SCIEO-2 copolymer with sufficiently long PEO block behaves as an effective stabilizer for the synthesis of CdS nanoparticles embedded in micelles, while SCIEO-1 does not. The morphology of aggregates varies with the Cd-to-SCI ratios and ranges from spherical to mixture of spherical and necklace-like micellar aggregates. A number of experimental techniques including static and dynamic light scattering, fluorescence correlation spectroscopy, atomic force and transmission electron microscopy, UV-vis, and fluorescence spectroscopy were employed for the characterization of both CdS containing hybrid micelles and embedded CdS nanoparticles. 相似文献
157.
Mariusz Walkowiak Daniel Waszak Błażej Gierczyk Grzegorz Schroeder 《Central European Journal of Chemistry》2008,6(4):600-606
Impact of silicon tripodand-type electrolyte additives and graphite pre-treatment agents on the electrochemical intercalation
of lithium cations into graphite was investigated. Addition of Si-tripodand-type silanes to propylene carbonate-based electrolytes
was found to suppress detrimental solvent co-intercalation and graphite exfoliation. Similar effects were observed for graphite
pre-treated with the reported silane agents. It was observed that the presented supramolecular additives allow for the formation
of effective passive layers on graphite during first charging, and thus can be considered as novel low-cost film-forming components
for rechargeable lithium batteries.
相似文献
158.
Benjamin F. Plummer W. Gregory Reese William H. Watson Mariusz Krawiec 《Structural chemistry》1993,4(1):53-57
A molecular mechanics simulation of the structure of 7,14-dicarbonylethoxyacenaphth[l,2-k]fluoranthene,1, indicated a preferred geometry for the hindered substituents in which the carbonyl groups were constrained to an anti conformation because of the steric hindrance associated with the in-plane buttressing hydrogen atoms. X-ray crystallographic analysis of1 verifies the correctness of the computation. Compound1 and tetracyanoquinodimethane,2, form a charge transfer complex, and a crystal structure analysis shows a slightly offset, nearly parallel arrangement of the acceptor with the cloud of the donor. The interplanar distance of 3.45 Å between acceptor and donor lies within the statistical limits of the interplanar distance of complexes formed between2 and a variety of PAH donors. The steric hindrance caused by the substituents in1 appears to offer only minimal interference to the formation of the complex. 相似文献
159.
Bollermann T Cadenbach T Gemel C Freitag K Molon M Gwildies V Fischer RA 《Inorganic chemistry》2011,50(12):5808-5814
The reactions of molybdenum(0) and rhodium(I) olefin containing starting materials with the carbenoid group 13 metal ligator ligand GaR (R = Cp*, DDP; Cp* = pentamethylcyclopentadienyl, DDP = HC(CMeNC(6)H(3)-2,6-(i)Pr(2))(2)) were investigated and compared. Treatment of [Mo(η(4)-butadiene)(3)] with GaCp* under hydrogen atmosphere at 100 °C yields the homoleptic, hexa coordinated, and sterically crowded complex [Mo(GaCp*)(6)] (1) in good yields ≥50%. Compound 1 exhibits an unusual and high coordinated octahedral [MoGa(6)] core. Similarly, [Rh(GaCp*)(5)][CF(3)SO(3)] (2) and [Rh(GaCp*)(5)][BAr(F)] (3) (BAr(F) = B{C(6)H(3)(CF(3))(2)}(4)) are prepared by the reaction of GaCp* with the rhodium(I) compound [Rh(coe)(2)(CF(3)SO(3))](2) (coe = cyclooctene) and subsequent anion exchange in case of 3. Compound 2 features a trigonal bipyramidal [RhGa(5)] unit. In contrast, reaction of excess Ga(DDP) with [Rh(coe)(2)(CF(3)SO(3))](2) does not result in a high coordinated homoleptic complex but instead yields [(coe)(toluene)Rh{Ga(DDP)}(CF(3)SO(3))] (4). The common feature of 2 and 4 in the solid state structure is the presence of short CF(3)SO(2)O···Ga contacts involving the GaCp* or rather the Ga(DDP) ligand. Compounds 1, 2, and 4 have been fully characterized by single crystal X-ray diffraction, variable temperature (1)H and (13)C NMR spectroscopy, IR spectroscopy, mass spectrometry, as well as elemental analysis. 相似文献
160.
Rafał Wysokiński Wiktor Zierkiewicz Mariusz Michalczyk Steve Scheiner 《Chemphyschem》2020,21(11):1119-1125
High-level ab initio calculations show that the MCl3− anions comprising Group 2B M atoms Zn, Cd, and Hg form a stable complex with the CN− anion, despite the like charge of the two ions. The complexation occurs despite a negative π-hole region above the M atom of MCl3−. The dimerization distorts the planar geometry of MCl3− into a pyramidal shape which reduces the negative potential above the M atom, facilitating a close approach of the two anions, with R(M⋅⋅⋅C)∼2 Å, and an overall attractive electrostatic attraction within the dimer. In the gas phase, this dimer is less stable than the pair of separated ions by some 30 kcal/mol. However, the dissociation must surmount an energy barrier of roughly 25 kcal/mol which occurs at an intermolecular distance of 4 Å. In aqueous solution, the dimerization process is exothermic and barrier-free, with a binding energy in the 11–18 kcal/mol range. 相似文献