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51.
Hiroo Hasebe Hironori Kuboki Hiroki Okuno Isao Yamane Hiroshi Imao Nobuhisa Fukunishi Masayuki Kase Osamu Kamigaito 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(2):1013-1018
New carbon-nanotube–sputter-deposition-carbon (CNT–SDC) foils were developed and used in the U beam time at the RIKEN RI Beam Factory (RIBF) from October to December 2011. The lifetimes of these new foils were drastically extended, and stable, high-intensity U beams were successfully provided to users. The lifetime of the CNT–SDC foils was 2–5 C, which was 100 times longer than those of static C-foils previously used. The qualitative analysis of the CNT–SDC foils clearly showed that the CNT structure and bundles were broken by beam irradiation. In addition, it was found that CNT bundles in the CNT–SDC foil were grown after the carbon deposition procedure. This structure was considered to be the reason that the CNT–SDC foils maintain advantages of both CNT and SDC foils. 相似文献
52.
Joshua Kyle Stanfield Keita Omura Ayaka Matsumoto Chie Kasai Hiroshi Sugimoto Yoshitsugu Shiro Yoshihito Watanabe Osami Shoji 《Angewandte Chemie (International ed. in English)》2020,59(19):7611-7618
Despite CYP102A1 (P450BM3) representing one of the most extensively researched metalloenzymes, crystallisation of its haem domain upon modification can be a challenge. Crystal structures are indispensable for the efficient structure‐based design of P450BM3 as a biocatalyst. The abietane diterpenoid derivative N‐abietoyl‐l ‐tryptophan (AbiATrp) is an outstanding crystallisation accelerator for the wild‐type P450BM3 haem domain, with visible crystals forming within 2 hours and diffracting to a near‐atomic resolution of 1.22 Å. Using these crystals as seeds in a cross‐microseeding approach, an assortment of P450BM3 haem domain crystal structures, containing previously uncrystallisable decoy molecules and diverse artificial metalloporphyrins binding various ligand molecules, as well as heavily tagged haem‐domain variants, could be determined. Some of the structures reported herein could be used as models of different stages of the P450BM3 catalytic cycle. 相似文献
53.
Mineto Uchiyama Masahiro Osumi Kotaro Satoh Masami Kamigaito 《Angewandte Chemie (International ed. in English)》2020,59(17):6832-6838
Thiol‐ene cationic and radical reactions were conducted for 1:1 addition between a thiol and vinyl ether, and also for cyclization and step‐growth polymerization between a dithiol and divinyl ether. p‐Toluenesulfonic acid (PTSA) induced a cationic thiol‐ene reaction to generate a thioacetal in high yield, whereas 2,2′‐azobisisobutyronitrile resulted in a radical thiol‐ene reaction to give a thioether, also in high yield. The cationic and radical addition reactions between a dithiol and divinyl ether with oxyethylene units yielded amorphous poly(thioacetal)s and crystalline poly(thioether)s, respectively. Under high‐dilution conditions, the cationic and radical reactions resulted in 16‐ and 18‐membered cyclic thioacetal and thioether products, respectively. Furthermore, concurrent cationic and radical step‐growth polymerizations were realized using PTSA under UV irradiation to produce polymers having both thioacetal and thioether linkages in the main chain. 相似文献
54.
Stereospecific Cyclic Poly(methyl methacrylate) and Its Topology‐Guided Hierarchically Controlled Supramolecular Assemblies 下载免费PDF全文
Jing Ming Ren Prof. Kotaro Satoh Dr. Tor Kit Goh Dr. Anton Blencowe Dr. Kanji Nagai Dr. Kenji Ishitake Dr. Andrew Joseph Christofferson Dr. George Yiapanis Prof. Irene Yarovsky Prof. Masami Kamigaito Prof. Greg Guanghua Qiao 《Angewandte Chemie (International ed. in English)》2014,53(2):459-464
In this study, the stereocomplexation between a novel stereospecific cyclic vinyl polymer, that is, cyclic syndiotactic poly(methyl methacrylate) (st‐PMMA), with the complementary linear isotactic (it‐) PMMA was investigated. Surprising new insight into the effects of the topology (i.e., end groups), size, and tacticity of the assembling components on stereocomplex formation was obtained. Characterization of the stereocomplexes revealed that the self‐assembly of cyclic st‐PMMAs and linear it‐PMMAs resulted in the formation of an unprecedented “polypseudorotaxane‐type” supramolecular assembly. This stereocomplex exhibited remarkably different physical properties as compared to the conventional PMMA triple‐helix stereocomplex as a result of the restricted topology imposed by the cyclic st‐PMMA assembling component. 相似文献
55.
Yoshitsugu Kojima Arimitsu Usuki Masaya Kawasumi Akane Okada Toshio Kurauchi Osami Kamigaito Keisuke Kaji 《Journal of Polymer Science.Polymer Physics》1995,33(7):1039-1045
Nylon 6-clay hybrid (NCH) is a molecular composite of Nylon 6 and uniformly dispersed silicate monolayers of montmorillonite. In this study the preferred orientation of montmorillonite and Nylon-6 crystallites in a thick (3 mm) injection-molded bar of NCH has been investigated using x-ray diffraction and electron micrography (TEM). It is clear that this bar has a triple layer structure consisting of surface, intermediate, and middle layers which have different preferred orientation. In the surface layer both the silicate monolayers and the chain axes of Nylon-6 crystallites are parallel to the bar surface though the latter are randomly oriented within the plane. In the intermediate layer the silicate monolayers remain parallel to the bar surface but the Nylon-6 crystallites rotate by 90° so that the chain axes would be perpendicular to the bar surface or the silicate monolayers. In the middle layer the silicate monolayers are randomly oriented around the flow axis of the NCH bar while remaining parallel to it, and the Nylon crystallites are randomly oriented around the flow axis while keeping their chain axes perpendicular to the silicate monolayers. It may be concluded that such preferred orientation of Nylon 6 crystallites is induced by the clay because the crystallites in the pure Nylon 6 bar have no preferred orientation. ©1995 John Wiley & Sons, Inc. 相似文献
56.
Sandberg MO Nagao O Wu Z Matsushita MM Sugawara T 《Chemical communications (Cambridge, England)》2008,(32):3738-3740
Enhancement of the electron acceptor ability of a para-quinodiimine unit by double protonation leads to the proton-induced intramolecular electron transfer from the donor unit to the cross-conjugated acceptor, giving rise to ground state triplet diradical reversibly. 相似文献
57.
Polysaccharide-based chiral packing materials (CPMs) for high-performance liquid chromatography have frequently been used not only to determine the enantiomeric excess of chiral compounds but also to preparatively resolve a wide range of racemates. However, these CPMs can be used with only a limited number of solvents as mobile phases because some organic solvents, such as tetrahydrofuran, chloroform, and so on, dissolve or swell the polysaccharide derivatives coated on a support, e.g., silica gel, and destroy their packed columns. The limitation of mobile phase selection is sometimes a serious problem for the efficient analytical and preparative resolution of enantiomers. This defect can be resolved by the immobilization of the polysaccharide derivatives onto silica gel. Efficient immobilizations have been attained through the radical copolymerization of the polysaccharide derivatives bearing small amounts of polymerizable residues and also through the polycondensation of the polysaccharide derivatives containing a few percent of 3-(triethoxysilyl)propyl residue. 相似文献
58.
Mineto Uchiyama Prof. Dr. Kotaro Satoh Prof. Dr. Masami Kamigaito 《Angewandte Chemie (International ed. in English)》2015,54(6):1924-1928
A metal‐free, cationic, reversible addition–fragmentation chain‐transfer (RAFT) polymerization was proposed and realized. A series of thiocarbonylthio compounds were used in the presence of a small amount of triflic acid for isobutyl vinyl ether to give polymers with controlled molecular weight of up to 1×105 and narrow molecular‐weight distributions (Mw/Mn<1.1). This “living” or controlled cationic polymerization is applicable to various electron‐rich monomers including vinyl ethers, p‐methoxystyrene, and even p‐hydroxystyrene that possesses an unprotected phenol group. A transformation from cationic to radical RAFT polymerization enables the synthesis of block copolymers between cationically and radically polymerizable monomers, such as vinyl ether and vinyl acetate or methyl acrylate. 相似文献
59.
Dr. Mineto Uchiyama Masahiro Osumi Prof. Dr. Kotaro Satoh Prof. Dr. Masami Kamigaito 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(17):6899-6905
Thiol-ene cationic and radical reactions were conducted for 1:1 addition between a thiol and vinyl ether, and also for cyclization and step-growth polymerization between a dithiol and divinyl ether. p-Toluenesulfonic acid (PTSA) induced a cationic thiol-ene reaction to generate a thioacetal in high yield, whereas 2,2′-azobisisobutyronitrile resulted in a radical thiol-ene reaction to give a thioether, also in high yield. The cationic and radical addition reactions between a dithiol and divinyl ether with oxyethylene units yielded amorphous poly(thioacetal)s and crystalline poly(thioether)s, respectively. Under high-dilution conditions, the cationic and radical reactions resulted in 16- and 18-membered cyclic thioacetal and thioether products, respectively. Furthermore, concurrent cationic and radical step-growth polymerizations were realized using PTSA under UV irradiation to produce polymers having both thioacetal and thioether linkages in the main chain. 相似文献
60.
Otsubo K Haraguchi T Sakata O Fujiwara A Kitagawa H 《Journal of the American Chemical Society》2012,134(23):9605-9608
Fabrication of a crystalline ordered thin film based on the porous metal-organic frameworks (MOFs) is one of the practical applications of the future functional nanomaterials. Here, we report the creation of a highly oriented three-dimensional (3-D) porous pillared-layer-type MOF thin film on a metal substrate using a step-by-step approach based on liquid-phase epitaxy. Synchrotron X-ray diffraction (XRD) study clearly indicates that the thin film is crystalline and its orientation is highly controlled in both horizontal and vertical directions relative to the substrate. This report provides the first confirmation of details of not only the crystallinity but also the orientation of 3-D MOF thin film using synchrotron XRD. Moreover, we also demonstrate its guest adsorption/desorption behavior by using in situ XRD measurements. The results presented here would promise useful insights for fabrication of MOF-based nanodevices in the future. 相似文献