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121.
Motoyanagi J Fukushima T Ishii N Aida T 《Journal of the American Chemical Society》2006,128(13):4220-4221
A coumarin-appended amphiphilic hexa-peri-hexabenzocoronene (1) self-assembled to form graphitic nanotubes. Upon irradiation of lambda > 300 nm, the nanotubes in the solid state and suspension both underwent dimerization of the coumarin pendants, affording covalently stitched nanotubes, which were hardly soluble in CHCl3, a good solvent of 1. In contrast, a thin film cast from a homogeneous solution of 1 was intact to photoirradiation. Owing to the reversible nature of the photochemical stitching, both negative and positive patterns of the graphitic nanotubes were developed on a silicon substrate by a lithographic post processing. 相似文献
122.
Sajeli B Sahai M Suessmuth R Asai T Hara N Fujimoto Y 《Chemical & pharmaceutical bulletin》2006,54(4):538-541
Hyosgerin, a new optically active coumarinolignan, has been isolated and characterized along with three other coumarinolignans, venkatasin, cleomiscosin A and cleomiscosin B, from the seeds of Hyoscyamus niger L. The structure was determined on the basis of spectroscopic analysis and chemical conversion. The optical properties and absolute stereochemistry of these coumarinolignans have also been studied and discussed. 相似文献
123.
Treatment of [RuCl(2)(DMSO)(4)] with 2-aminoethanethiol (Haet) in ethanol gave a dicationic triruthenium complex, [Ru[Ru(aet)(3)](2)]Cl(2) ([1]Cl(2)). Complex [1]Cl(2) was also obtained by treatment of RuCl(3).nH(2)O with excess Haet in water. When [1](2+) was chromatographed on a cation-exchange column of SP-Sephadex C-25, meso (DeltaLambda) and racemic (DeltaDelta/LambdaLambda) isomers of the corresponding tricationic complex, [Ru[Ru(aet)(3)](2)](3+) ([2](3+)), were eluted with aqueous NaNO(3). The racemic isomer of [2](3+) was optically resolved into DeltaDelta and LambdaLambda isomers by using [Sb(2)(R,R-tartrato)(2)](2-) as a resolving agent. The molecular structures of DeltaLambda- and DeltaDelta/LambdaLambda-[2](NO(3))(3) were determined by X-ray crystallography. In these complexes, the central Ru atom is coordinated by six thiolato groups from two terminal fac-(S)-[Ru(aet)(3)] units in an octahedral geometry, forming a linear-type S-bridged triruthenium structure. The spectroelectrochemical studies on the electronic absorption and CD spectra, together with the electrochemical studies, demonstrated that [1](2+) and [2](3+) are interconvertible with each other through a one-electron redox process, retaining the chirality of the triruthenium structure. Their electronic structures were investigated on the basis of EPR and magnetic susceptibility measurements, which indicated that [1](2+) and [2](3+) have spin ground states of S(t) = 0 and S(t) = 1/2, respectively. The corresponding L-cysteinato complex, [Ru[Ru(L-cys-N,S)(3)](2)](3-), which was formed from RuCl(3).nH(2)O and excess L-cysteine (L-H(2)cys) in water followed by air oxidation, is also presented. 相似文献
124.
An asymmetric total synthesis of komaroviquinone (1), which is a natural product isolated from Dracocephalum komarovi and shows novel potent trypanocidal activity, was achieved in five steps from the known starting materials. The synthetic route is shorter and more efficient than the reported methods and also useful for the scale-up synthesis. 相似文献
125.
Wei‐Shi Li Prof. Dr. Akinori Saeki Dr. Yohei Yamamoto Dr. Takanori Fukushima Dr. Shu Seki Prof. Dr. Noriyuki Ishii Dr. Kenichi Kato Dr. Masaki Takata Prof. Dr. Takuzo Aida Prof. Dr. 《化学:亚洲杂志》2010,5(7):1566-1572
To tailor organic p/n heterojunctions with molecular‐level precision, a rational design strategy using side‐chain incompatibility of a covalently connected donor–acceptor (D–A) dyad has been successfully carried out. An oligothiophene–perylenediimide dyad, when modified with triethylene glycol side chains at one terminus and dodecyl side chains at the other ( 2 Amphi ), self‐assembles into nanofibers with a long‐range D/A heterojunction. In contrast, when the dyad is modified with dodecyl side chains at both termini ( 2 Lipo ), ill‐defined microfibers result. In steady‐state measurements using microgap electrodes, a cast film of the nanofiber of 2 Amphi displays far better photoconducting properties than that of the microfiber of 2 Lipo . Flash‐photolysis time‐resolved microwave conductivity measurements, in conjunction with transient absorption spectroscopy, clearly indicate that the nanofiber of 2 Amphi intrinsically allows for better carrier generation and transport properties than the microfibrous assembly of 2 Lipo . 相似文献
126.
Thin film capacitors with a thickness of 200 nm were prepared on SrTiO3 (1 0 0), (1 1 0) and (1 1 1) single crystal substrates at a temperature of 973 K by pulsed laser deposition (PLD) using a KrF excimer laser in an O2-O3 atmosphere with a gas pressure of 1 Pa using an X7R sintered target. As a result, perovskite BaTiO3 solid solution films were obtained. In the X7R thin films on (1 0 0) and (1 1 0) SrTiO3, only diffraction peaks with strong intensities from BaTiO3 (1 0 0) and (1 1 0), respectively, were observed. X7R films on SrTiO3 (1 1 1) were grown epitaxially oriented to the crystal plane direction of the substrate by inserting an initial homoepitaxial SrTiO3 layer with a thickness of 4 nm. The X7R/SrTiO3 film capacitors yielded a large volumetric efficiency of 50 μF/mm3 and a temperature coefficient of capacitance (TCC) of −1.3% to 1.3% which satisfies the EIA standard specifications for X7R. 相似文献
127.
128.
Tsutomu Kumagai Takumi Nittono Noriyuki Tanaka Toshio Mukai 《Tetrahedron letters》1985,26(49):6093-6096
Upon irradiation, 2-dicyanomethylenebenzonorbornene f was converted into 1-dicyanomethylenebenzobicyclo[3.1.1]heptene . The reaction pathway is discussed with reference to the photoreaction of parent hydrocarbon. 相似文献
129.
Noriyuki Kuramoto Takeshi Iwaki Akihiro Satoh Katsutoshi Nagai 《Journal of polymer science. Part A, Polymer chemistry》1989,27(1):367-374
Copolymerization of styrene (ST) with maleic anhydride (MAH) initiated by thiol compound was investigated under various conditions. The kinetics of copolymerization of ST with MAH initiated by p-toluenethiol (pTT) was studied in dioxane in the temperature range of 25–60°C, and the rates (Rp) of copolymerization and activation energy were determined. Rp was found to depend on [pTT],0.6 ([ST] + [MAH])2.7. The overall energy of activation was 10.8 kcal/mol in the temperature range of 25–60°C. A mechanism involving the formation of a complex between MAH and pTT the decomposition of which yields the initial radical is suggested. 相似文献
130.
Noriyuki Miyauchi Isamu Kirikihira Xin Li Mitsuru Akashi 《Journal of polymer science. Part A, Polymer chemistry》1988,26(6):1561-1571
Graft copolymers were synthesized by the esterification reaction between acrylic copolymers and carboxyl group terminated vinylpyrrolidone oligomer using phase transfer catalysts. Acrylic copolymers were obtained by the radical copolymerization of β-bromoethyl methacrylate, chloromethylstyrene or glycidyl methacrylate with methyl methacrylate. Hydrophilic oligomers were prepared by the radical oligomerization of vinylpyrrolidone using β-mercaptopropionic acid as chain transfer agent. The degree of esterification increased with decreasing the molecular weight of oligomer and with increasing the number of potential grafting sites on polymer backbones. The water dispersibility of graft copolymers increased with increasing the nitrogen content and was therefore dependent on the branch oligomer content. 相似文献