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排序方式: 共有218条查询结果,搜索用时 406 毫秒
101.
Takanobu Saitou Yushu Jin Kotaro Isobe Takuya Suga Jun Takaya Nobuharu Iwasawa 《化学:亚洲杂志》2020,15(13):1941-1944
The Rh‐catalyzed direct carboxylation of alkenyl C?H bonds was achieved by using pyrazole as a removable directing group. In the presence of 5 mol% RhCl3 ? 3H2O, 6 mol% P(Mes)3, and 2 equiv. of AlMe2(OMe), the alkenyl C?H bond of various alkenylpyrazoles was directly carboxylated in good yields under CO2 atmosphere. Furthermore, several useful transformations of the pyrazole moiety of the product were achieved to afford synthetically useful carboxylic acid derivatives in good yields. 相似文献
102.
Chitose Nagao Mitsuo Sawamoto Takaya Terashima 《Journal of polymer science. Part A, Polymer chemistry》2020,58(1):215-224
We report amphiphilic folded polymers with imprinted nanocavities for selective molecular recognition in water. For this, a molecular imprinting technique is applied to the polymer synthesis: amphiphilic polymer micelles interacting with template molecules are crosslinked in water to fix the folded architecture and memorize the template structure within the polymers; the removal of the templates provides imprint polymers bearing template-specific nanospaces. Here, a hydrophilic dye bearing two anionic groups, Orange G (OG), is used as a model template. For the imprinting, we design amphiphilic random copolymers bearing hydrophilic poly(ethylene glycol) (PEG) chains, hydrophobic olefin groups, and quaternary ammonium groups that can interact with the template. The copolymers were prepared by living radical polymerization and post functionalization. In the presence of OG and methyl blue (MB), the imprinted nanocavity polymers simultaneously capture both of the dyes in water. The total number of encapsulated dyes increased with increasing the number of polymer-bound quaternary ammonium groups. The selectivity of OG against MB increased with the crosslinking density, while imprint polymers encapsulated OG more efficiently than nonimprint polymers. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 215–224 相似文献
103.
Yoshiaki Takaya 《Tetrahedron》2005,61(43):10285-10290
Resveratrol was treated with several kinds of peroxidases and inorganic reagents so as to prepare ε-viniferin. Among several inorganic reagents, which were investigated in this study, thallium(III) nitrate in methanol gave (±)-ε-viniferin in the yield of 68%. On the other hand, peroxidases did not lead to ε-viniferin, but some stilbenedimers such as pallidol, resveratrol trans-dehydrodimer, and leachianol F were obtained. 相似文献
104.
Takaya Terashima Makoto Ouchi Tsuyoshi Ando Masami Kamigaito Mitsuo Sawamoto 《Journal of polymer science. Part A, Polymer chemistry》2006,44(17):4966-4980
One-pot, spontaneous, and in-situ incorporation of Ru(II) complexes into a microgel (solubilized nanometer-scale network) has been achieved in near quantitative efficiency by a polymer-linking reaction of linear living poly(methyl methacrylate) (PMMA) with a bifunctional methacrylate (ethylene glycol dimethacrylate or bisphenol A dimethacrylate; linking agent) and a phosphine-ligand monomer [diphenyl-4-styryl-phosphine ( 3 ); i.e., CH2CH C6H4 p-PPh2] in the RuCl2(PPh3)3-catalyzed living radical polymerization. The products were Ru-bearing. PMMA-armed star polymers with a microgel-core that consisted of a copolymer network of the linking agent and 3 . Upon the network formation, the phosphine ligands efficiently encapsulated RuCl2(PPh3)3, thus achieving a polymer catalyst directly from a polymerization catalyst. Colored dark brown-red, the star polymers exhibited UV-vis absorptions originating from the entrapped complex (3.1–7.4 × 10−5 mol Ru/g of polymer), the incorporation efficiency being close to 100% with respect to the original polymerization-catalyst. Detailed spectroscopic characterization showed the following: an absolute molecular weight of 1.7 × 105 to 1.7 × 106, an arm number of 11–92 arms/polymer, and a radius of gyration of 8–19 nm (in DMF). Direct observation of the individual star molecules in solid state was achieved by transmission electron microscopy (unstained; 2–3 nm dark dots for the core) and atomic force microscopy (semi-circular images). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4966–4980, 2006 相似文献
105.
Satoh T Sato T Kubo A Tamura J 《Journal of the American Society for Mass Spectrometry》2011,22(5):797-803
In this study, we have developed a tandem time-of-flight mass spectrometry (TOF/TOF) technique involving the use of a matrix-assisted
laser desorption/ionization ion source that exhibits high precursor ion selectivity. An ion optical system with a 17 m spiral
ion trajectory was used in the first time-of-flight mass spectrometer. High precursor ion selectivity was achieved by realizing
a 15 m flight path, which is considerably longer than that of the conventional MALDI-TOF/TOF before the precursor ion selection
by an ion gate; monoisotopic ions could be selected properly up to m/z 2500. Furthermore, the first time-of-flight mass spectrometer was composed of electrostatic sectors and could eliminate post-source
decay (PSD) ions. Precursor ions with 20 keV kinetic energy were selected and injected into a collision cell, leading to the
generation of fragment ions by high-energy collision-induced dissociation (HE-CID). The optimized second time-of-flight mass
spectrometer included a post-acceleration region and an offset parabolic reflectron to record product ion spectra in the entire
mass range. Our system could generate a simple HE-CID product ion spectrum because each fragment pathway could be observed
as a single peak by the selection of monoisotopic ions of all precursor ions and HE-CID fragment pathways could be predominantly
observed by the PSD ion elimination. 相似文献
106.
An efficient one-to-one coupling reaction of atmospheric pressure carbon dioxide with 1,3-dienes is realized for the first time through PSiP-pincer type palladium-catalyzed hydrocarboxylation. The reaction is applicable to various 1,3-dienes including easily available chemical feedstock such as 1,3-butadiene and isoprene. This protocol affords a highly useful method for the synthesis of β,γ-unsaturated carboxylic acid derivatives from CO(2). 相似文献
107.
Single-chain folding of polymers for catalytic systems in water 总被引:1,自引:0,他引:1
Terashima T Mes T De Greef TF Gillissen MA Besenius P Palmans AR Meijer EW 《Journal of the American Chemical Society》2011,133(13):4742-4745
Enzymes are a source of inspiration for chemists attempting to create versatile synthetic catalysts. In order to arrive at a polymeric chain carrying catalytic units separated spatially, it is a prerequisite to fold these polymers in water into well-defined compartmentalized architectures thus creating a catalytic core. Herein, we report the synthesis, physical properties, and catalytic activity of a water-soluble segmented terpolymer in which a helical structure in the apolar core is created around a ruthenium-based catalyst. The supramolecular chirality of this catalytic system is the result of the self-assembly of benzene-1,3,5-tricarboxamide side chains, while the catalyst arises from the sequential ruthenium-catalyzed living radical polymerization of the different monomers followed by ligand exchange. The polymers exhibit a two-state folding process and show transfer hydrogenation in water. 相似文献
108.
Ko Mibu Makoto Seto Takaya Mitsui Yoshitaka Yoda Ryo Masuda Shinji Kitao Yasuhiro Kobayashi Edi Suharyadi Masaaki Tanaka Masakiyo Tsunoda Hideto Yanagihara Eiji Kita 《Hyperfine Interactions》2013,217(1-3):127-135
Applications of synchrotron-radiation-based Mössbauer spectroscopy in the “energy domain” to the studies on magnetism of thin films are introduced on the basis of the experiments recently performed at SPring-8, Japan. The measured samples are spintronics-related thin films, such as Co2MnSn films, layered Fe/Cr films, layered Fe/Fe3O4 films, and Fe4N films. The validity of the energy domain measurements is demonstrated in the light of industrial applications of magnetic thin films. 相似文献
109.
Susan K. Kozawa Kazuma Matsumoto Ayaka Suzuki Mitsuo Sawamoto Takaya Terashima 《Journal of polymer science. Part A, Polymer chemistry》2019,57(3):313-321
Self‐assembly of amphiphilic ABA random triblock copolymers in water serves as a novel approach to create unique structure micelles connected with flexible linkages. The ABA triblock copolymers consist of amphiphilic random copolymers bearing hydrophilic poly(ethylene glycol) and hydrophobic dodecyl pendants as the A segments and a hydrophilic poly(ethylene oxide) (PEO) as the middle B segment. The A block is varied in dodecyl methacrylate content of 20%–50% and degree of polymerization (DP) of 100‐200. By controlling the composition and DP of the A block, various architectures can be tailor‐made as micelles in water: PEO‐linked double core unimer micelles, PEO‐looped unimer or dimer micelles, and multichain micelles. Those PEO‐linked or looped micelles further exhibit thermoresponsive solubility in water. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 313–321 相似文献
110.