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41.
Ferrocene-bridged trisporphyrin (2) was synthesized by two-steps condensation of corresponding aldehydes and dipyrromethanes, and its self-assembling behavior based on the complementary coordination motif of imidazolylporphyrinatozinc(II) was investigated in conjunction with hinge-like flexibility given by freely rotating cyclopentadienyl rings of ferrocene connector. Ferrocene-bridged trisporphyrin (2) spontaneously and exclusively generated the dimeric ring (7) upon simple zinc(II) insertion, indicating that the freely rotating hinge connector favored the smallest ring formation. Taking advantage of the unique hinge-like flexibility of ferrocene, we attempted to transform the dimer ring into a mixture of porphyrin macrocycles by reorganizing the structure cleaved once by pyridine. A series of porphyrin macrocycles from trimer to decamer can be separated into its components by preparative gel permeation chromatograms. Macrocycles obtained are kept stable in the absence of coordinating solvents. On the other hand, they were easily transformed to the dimer ring in the presence of coordinating solvents such as methanol, showing that the transformation is completely reversible and can be controlled by the choice of the solvent system. A series of porphyrin macrocycles was confirmed via covalent linking of each complementary coordination dimer pair by metathesis reaction in the presence of Grubbs's catalyst. The coordination behavior of the bidentate ligands with different spacer lengths toward the dimer ring revealed that only the bidentate ligand (15) with a spacer length that matched the facing central porphyrins was selectively accommodated inside the ring. Coordination assembled flexible rings with tunable cavities and multiple coordination sites will be used as versatile hosts for a wide variety of guest molecules. 相似文献
42.
Masahide Senoo Yuzo Kotani Masami Kamigaito Mitsuo Sawamoto 《Macromolecular Symposia》2000,157(1):193-200
RuCl2(PPh3)3 led to living radical copolymerization of N,N‐dimethylacrylamide (DMAA) and methyl methacrylate (MMA) in conjunction with a halide‐initiator (R‐X; CHCl2COPh, CCl3Br) and Al(Oi‐Pr)3 in toluene at 80°C. Both the monomers were polymerized at almost the same rate into random copolymers, where the number‐average molecular weights (Mn) increased in direct proportion to weight of the obtained polymers, and the molecular weight distributions (MWDs) were narrow throughout the reactions (Mw/Mn = 1.2‐1.6). MMA was consumed faster in the copolymerization than in the homopolymerization, which was due to the interaction of DMAA with the ruthenium complex. The Ru(II)‐based initiating system was also effective in block copolymerization of DMAA and MMA. 相似文献
43.
Yuya Sugiyama Kotaro Satoh Masami Kamigaito Yoshio Okamoto 《Journal of polymer science. Part A, Polymer chemistry》2006,44(6):2086-2098
This work is directed to the stereospecific living radical polymerization of acrylamides such as N,N‐dimethylacrylamide and N‐isopropylacrylamide with an iron complex and a Lewis acid. DMAM was polymerized with [FeCp(CO)2]2 in conjunction with an alkyl iodide [(CH3)2C(CO2Et)I] as an initiator in the presence of Y(OTf)3 in toluene/methanol (1/1) at 60 °C to be converted almost quantitatively to the polymers with controlled molecular weights and high isotacticity (m > 80%), wherein the Fe‐complex generates radical species from a covalent C? I bond of the dormant species and the Lewis acid controls the stereochemistry of the polymerization via coordination with the amide groups of the polymer terminal and the monomer. A series of Lewis acids were also used for the iron(I)‐catalyzed DMAM polymerization, and Yb(OTf)3 and Yb(NTf2)3 proved effective in giving isotactic polymers without deteriorating the molecular weight control similar to Y(OTf)3. Furthermore, a slight enhancement of isospecificity was observed for the iron‐catalyzed system in comparison with the α,α‐Azobisisobutyronitrile‐initiated, when coupled with Y(OTf)3. Stereoblock polymerization of DMAM via a one‐pot reaction was also achieved by just adding the Y(OTf)3 methanol solution in the course of the polymerization to give atactic‐b‐isotactic poly(DMAM). A similar but slightly lower control in the molecular weight and tacticity was achieved in the polymerization of NIPAM with [FeCp(CO)2]2/Y(OTf)3. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2086–2098, 2006 相似文献
44.
T. Nakano M. Nakamura H. Sakaguchi M. Yosoi M. Ieiri H. Togawa S. Hirata O. Kamigaito H. M. Shimizu M. Iwaki Y. Nakai S. Kobayashi
T. Noro
H. Ikegami 《Physics letters. [Part B]》1990,240(3-4):301-305We have measured the angular distribution of the depolarization parameter Kyy′ in p-15N elastic scattering at 65 MeV. The deviation of Kyy′ from unity is large and indicates the existence of a nucleon-nucleus spin-spin interaction. The DWBA analysis shows that the measured Kyy′ data imply a large contribution from the tensor part of the spin-spin potential. 相似文献
45.
Kamigaito M Onishi I Kimura S Kotani Y Sawamoto M 《Chemical communications (Cambridge, England)》2002,(22):2694-2695
A fast and controlled radical polymerisation of acrylates and acrylamides can be achieved with a combination of a highly active metal catalyst, Fe2Cp2(CO)4, and a mild radical scavenger, iodine, in the presence of an iodide initiator. 相似文献
46.
Takeshi Kaneko Kazuya Suda Kotaro Satoh Masami Kamigaito Toshinori Kato Tomohiro Ono Eiji Nakamura Toshio Nishi Hiroshi Jinnai 《Macromolecular Symposia》2006,242(1):80-86
ABC triblock copolymers are known to exhibit a wide variety of unique types of morphologies compared to AB diblock copolymers. In the present study, poly(styrene-block-(ethylene-alt-propylene)-block-(methyl methacrylate)) (SEPM) triblock copolymers were synthesized and their morphologies were extensively studied by transmission electron microtomography (TEMT). In the SEPM triblock copolymer, two kinds of morphologies coexist: One was the well-known knitting morphology, and the other was a novel morphology called the “ladder morphology”. The ladder morphology was a major morphology in the SEPM copolymer, the stability of which was discussed in terms of the interfacial area and the solubility parameters between the three components. 相似文献
47.
48.
49.
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
50.
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