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Ammonia Activation by a Nickel NCN‐Pincer Complex featuring a Non‐Innocent N‐Heterocyclic Carbene: Ammine and Amido Complexes in Equilibrium 下载免费PDF全文
Rudy M. Brown Dr. Javier Borau Garcia Juuso Valjus Christopher J. Roberts Dr. Heikki M. Tuononen Dr. Masood Parvez Prof. Roland Roesler 《Angewandte Chemie (International ed. in English)》2015,54(21):6274-6277
A Ni0‐NCN pincer complex featuring a six‐membered N‐heterocyclic carbene (NHC) central platform and amidine pendant arms was synthesized by deprotonation of its NiII precursor. It retained chloride in the square‐planar coordination sphere of nickel and was expected to be highly susceptible to oxidative addition reactions. The Ni0 complex rapidly activated ammonia at room temperature, in a ligand‐assisted process where the carbene carbon atom played the unprecedented role of proton acceptor. For the first time, the coordinated (ammine) and activated (amido) species were observed together in solution, in a solvent‐dependent equilibrium. A structural analysis of the Ni complexes provided insight into the highly unusual, non‐innocent behavior of the NHC ligand. 相似文献
3.
Onur Yilmaz Mikko Karesoja A. Candas Adiguzel Gokhan Zengin Heikki Tenhu 《Journal of polymer science. Part A, Polymer chemistry》2014,52(10):1435-1447
Functional polymer/AgNPs nanocomposites have been prepared. Silver nanoparticles (NPs) were synthesized to which polyacrylamide, PAAm, was covalently bound. PAAm was synthesized via a RAFT reaction and carried thiol and carboxylic acid end groups. Thiol was used to bind the polymer to the metal surface and carboxyl for further reactions. The AgNPs were used in a post‐crosslinking reaction with a separately synthesized poly(butyl acrylate‐co‐methyl methacrylate)/polyglycidyl methacrylate core/shell latex bearing epoxy functional groups. Dynamic mechanical analysis showed that the functional AgNPs effectively crosslinked the latex polymer, and that the final product had excellent mechanical strength. Antibacterial tests revealed that the nanocomposite films had strong antibacterial activity against all types of the bacteria and the immobilization of silver NPs by crosslinking retarded the release of silver in comparison to the uncrosslinked ones. With the presented method, it is possible to obtain ductile antibacterial nanocomposites to be used as waterborne functional coatings. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1435–1447 相似文献
4.
The paper deals with the Backus-Gilbert or averaging kernel inversion of linear integral equations. The theoretical background of the method is developed: it is shown that the method leads to a sequence of linear pointwise estimates, which are asymptotically unbiased when no error is present. Anumerical implementation is given. Finally, the algorithm is applied to numerical differentiation, Laplace transform inversion and to a geophysical inverseproblem arising in electromagnetic sounding. 相似文献
5.
Sami-Pekka Hirvonen Mikko Mänttäri Valter Wigren Mikko Salomäki Carita Kvarnström Heikki Tenhu 《Colloid and polymer science》2011,289(9):1065-1072
Poly(benzimidazobenzophenanthroline) (BBL) was prepared according to literature method and modified with poly(ethylene oxide)
in a one pot synthesis. After precipitation in aqueous sodium carbonate solution and subsequent purification, aqueous dispersions
were prepared by ultrasonication. Particle sizes in the dispersions ranged from few tens of nanometers to several micrometers
and most of the particles had sizes of 50–250 nm. Further studies indicated that the colloidal stability is a combined result
of steric stabilization caused by excluded volume interactions of PEO chains on particle surface and electrostatic stabilization
by the dissociated carboxylic acid groups on the particle surface. The product could be processed into uniform films 20–30 nm
in thickness by spin coating onto gold-plated silicon substrates having aminethiol monolayer as the top most layer. 相似文献
6.
Joanna Witos Erno Karjalainen Heikki Tenhu Susanne K. Wiedmer 《Journal of separation science》2020,43(12):2495-2505
Amphiphilic diblock copolymers consisting of a hydrophobic core containing a polymerized ionic liquid and an outer shell composed of poly(N‐isoprolylacrylamide) were investigated by capillary electrophoresis and asymmetrical flow‐field flow fractionation. The polymerized ionic liquid comprised poly(2‐(1‐butylimidazolium‐3‐yl)ethyl methacrylate tetrafluoroborate) with a constant block length (n = 24), while the length of the poly(N‐isoprolylacrylamide) block varied (n = 14; 26; 59; 88). Possible adsorption of the block copolymer on the fused silica capillary, due to alterations in the polymeric conformation upon a change in the temperature (25 and 45 °C), was initially studied. For comparison, the effect of temperature on the copolymer conformation/hydrodynamic size was determined with the aid of asymmetrical flow‐field flow fractionation and light scattering. To get more information about the hydrophilic/hydrophobic properties of the synthesized block copolymers, they were used as a pseudostationary phase in electrokinetic chromatography for the separation of some model compounds, that is, benzoates and steroids. Of particular interest was to find out whether a change in the length or concentration of the poly(N‐isoprolylacrylamide) block would affect the separation of the model compounds. Overall, our results show that capillary electrophoresis and asymmetrical flow‐field flow fractionation are suitable methods for characterizing conformational changes of such diblock copolymers. 相似文献
7.
Common design principles apply to design of mechanical and biological machine structures. Most of the main properties of machines and creatures are determined by programmed genetics. These determine the geometry, material selection, functioning of machines and biological creatures and the fitness for service. The present approach of innovation and optimum design is based on basic mechanics with fuzzy goal formulations and heuristics, like axiomatic design. These models are combined synergistically to formulate the desired properties of the machines. First, engineering mechanics and heuristics are shown to have a finalistic guidance on the conceptual design of optimal fluid conveying channels consisting of a branch and a closing device. Then a multi-objective algorithm is tested in an industrial case study design of a preloaded screw fastened flange plate and it is shown to be a reliable tool for testing and innovating new solutions. The goals and constraints are modellled consistently by the same goal function form. The joints have to be reliable against risks of separation, relaxation, fatigue and creep fracture due to pressure differences. Compared to conventional results it gives nearly the same technical and safety functions even at half the cost. This approach is useful for optimizing new concepts and also existing machine designs showing possibilities for notable cost savings. 相似文献
8.
Heikki Torvela 《International journal of environmental analytical chemistry》2013,93(2):143-154
Abstract The determination of sulphur and heavy metals in plants is an integral part of many environmental studies. Pine needles (Pinus Sylvestris) have proved to be suitable air quality indicators for pollutants, especially for sulphur. This study was carried out in the vicinity of Kemi, a town situated on the Gulf of Bothnia in northern Finland. An industrial complex comprising two pulp and paper mills is located in the centre of the area. Scots pine (Pinus Sylvestris) needles were collected from 29 sampling sites. The samples were dried, homogenized and digested with nitric acid. The concentrations of the elements S, Fe, Zn, Ca, V, and Pb were determined by ICP-AES. According to our results pine needles (Pinus sylvestris) appear to be an ideal bioindicator and sampling material for identifying and assessing atmospheric sulphur pollution derived from pulp and paper mills and can complement the information provided by plant mapping studies around pulp and paper mills. 相似文献
9.
The use of a TDI camera is restricted to cases of viewing from the direction of the surface normal. Our previous work indicated that a TDI camera can be used with viewing angles up to 30° from the surface normal which extends the usability of TDI for visual inspection applications. The objective of this paper is to examine the use of a TDI camera at a non-zero viewing angle under vibration conditions. The effects caused by vibration of the surface to be viewed become critical when using a TDI camera at non-zero viewing angles. A method of approximating the TDI performance under vibration conditions was determined and evaluated experimentally. The resulting measurements support the approximating method developed here. 相似文献
10.
Felix A. Plamper Arjan P. Gelissen Jan Timper Andrea Wolf Alexander B. Zezin Walter Richtering Heikki Tenhu Ulrich Simon Joachim Mayer Oleg V. Borisov Dmitry V. Pergushov 《Macromolecular rapid communications》2013,34(10):855-860
Mixing a bis‐hydrophilic, cationic miktoarm star polymer with a linear polyanion leads to the formation of unilamellar polymersomes, which consist of an interpolyelectrolyte complex (IPEC) wall sandwiched between poly(ethylene oxide) brushes. The experimental finding of this rare IPEC morphology is rationalized theoretically: the star architecture forces the assembly into a vesicular shape due to the high entropic penalty for stretching of the insoluble arms in non‐planar morphologies. The transmission electron microscopy of vitrified samples (cryogenic TEM) is compared with the samples at ambient conditions (in situ TEM), giving one of the first TEM reports on soft matter in its pristine environment.