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101.
Okuno D Iwase T Shinzawa-Itoh K Yoshikawa S Kitagawa T 《Journal of the American Chemical Society》2003,125(24):7209-7218
FTIR spectral changes of bovine cytochrome c oxidase (CcO) upon ligand dissociation from heme a(3)() and redox change of the Cu(A)-heme a moiety (Cu(A)Fe(a)()) were investigated. In a photosteady state under CW laser illumination at 590 nm to carbonmonoxy CcO (CcO-CO), the C-O stretching bands due to Fe(a3)()(2+)CO and Cu(B)(1+)CO were identified at 1963 and 2063 cm(-)(1), respectively, for the fully reduced (FR) state [(Cu(A)Fe(a)())(3+)Fe(a3)()(2+)Cu(B)(1+)] and at 1965 and 2061 cm(-)(1) for the mixed valence (MV) state [(Cu(A)Fe(a)())(5+)Fe(a3)()(2+)Cu(B)(1+)] in H(2)O as well as in D(2)O. For the MV state, however, another band due to Cu(B)(1+)CO was found at 2040 cm(-)(1), which was distinct from the alpha/beta conformers in the spectral behaviors, and therefore was assigned to the (Cu(A)Fe(a)())(4+)Fe(a3)()(3+)Cu(B)(1+)CO generated by back electron transfer. The FR-minus-oxidized difference spectrum in the carboxyl stretching region provided two negative bands at 1749 and 1737 cm(-)(1) in H(2)O, which were apparently merged into a single band with a band center at 1741 cm(-)(1) in D(2)O. Comparison of these spectra with those of bacterial enzymes suggests that the 1749 and 1737 cm(-)(1) bands are due to COOH groups of Glu242 and Asp51, respectively. A similar difference spectrum of the carboxyl stretching region was also obtained between (Cu(A)Fe(a)())(3+)Fe(a3)()(2+)Cu(B)(1+)CO and (Cu(A)Fe(a)())(5+)Fe(a3)()(2+)Cu(B)(1+)CO. The results indicate that an oxidation state of the (Cu(A)Fe(a)()) moiety determines the carboxyl stretching spectra. On the other hand, CO-dissociated minus CO-bound difference spectra in the FR state gave rise to a positive and a negative peaks at 1749 and 1741 cm(-)(1), respectively, in H(2)O, but mainly a negative peak at 1735 cm(-)(1) in D(2)O. It was confirmed that the absence of a positive peak is not caused by slow deuteration of protein. The corresponding difference spectrum in the MV state showed a significantly weaker positive peak at 1749 cm(-)(1) and an intense negative peak at 1741 cm(-)(1) (1737 cm(-)(1) in D(2)O). The spectral difference between the FR and MV states is explained satisfactorily by the spectral change induced by the electron back flow upon CO dissociation as described above. Thus, the changes of carboxyl stretching bands induced both by oxidation of (Cu(A)Fe(a)()) and dissociation of CO appear at similar frequencies ( approximately 1749 cm(-)(1)) but are ascribed to different carboxyl side chains. 相似文献
102.
Joël Jacob Katrin Geßler Daniel Hoffmann Haruyo Sanbe Kyoko Koizumi Steven M. Smith Takeshi Takaha Wolfram Saenger 《Angewandte Chemie (International ed. in English)》1998,37(5):605-609
The cavity of the larger molecule has less space for guests! Unlike the structure of the smaller annular cyclodextrins, that of the higher homologues of cycloamyloses (CAs) with more than ten glucose units contains a 90° kink between adjacent glucose residues within one half of the molecule and a 180° band flip between adjacent units in different halves (see depicted section of the CA14 structure) to yield butterfly-shaped structures with narrow, groovelike cavities. 相似文献
103.
Polarized optical waveguide (POW) spectroscopy permits analysis of the changing molecular state of methylene blue (MB), including aggregate order and orientation at the waveguide surface. Monomer or dimer, dissolved randomly in MB aqueous solution, tends to aggregate at the waveguide surface during air drying. Furthermore, POW spectroscopy dynamically revealed that MB molecules became oriented vertically to the waveguide surface with increasing aggregation order. 相似文献
104.
Summary The precolumn derivatization of several primary aromatic amines, especially phenolamines, with 1-pyrenealdehyde, and their determination by high-performance liquid chromatography with fluorescence detection have been studied. The derivatization proceeded in methanol to form the Schiff bases, which were chromatographed on the ODS column. The detection limit is 1–2 pmol. 1-Pyrenealdehyde was evaluated as a derivatization reagent for the selective analysis of phenolamines such as 2-phenylethylamine, in biogenic aromatic amines. 相似文献
105.
Kyoko Koizumi Yasuyo Okada Shizuyo Horiyama Toshiko Utamura Tadashi Higashiura Masahiro Ikeda 《Journal of inclusion phenomena and macrocyclic chemistry》1984,2(3-4):891-899
Cyclosophoraoses (CySs) are unbranched cyclic (12)--D-glucans produced by many strains ofAgrobacterium andRhizobium. Pure CyS-A, the group member having the smallest molecular size (degree of polymerization 17), was efficiently prepared by liquid chromatography using charcoal and ODS columns from the culture fluid of the mutant strain RA-12 fromR. phaseoli AHU 1133. The complex-forming ability of CyS-A was estimated from its enhancement of the solubilities of slightly soluble guest molecules in water using methods [I], [II], and [III]. In [I], an aqueous solution of CyS-A was shaken with the guest molecule, while, in [II], it was shaken with an acetone solution of the guest compound. In method [III], freeze-dried CyS-A powder was stirred with an acetone solution of the guest compound. The CyS-A cavity is thought to be able to accommodate three-dimensionally extended guest molecules,e.g., indomethacin. Method [II] was the best for obtaining CyS-A inclusion complexes, while method [III] would be recommended if the guest molecule is labile in the presence of water. Crystalline CyS-A inclusion complexes have not been obtained, but CyS-A complexes are expected to greatly enhance the solubilities of slightly soluble or insoluble guest molecules in water, because CyS-A is much more soluble than -cyclodextrin. Method [II] or [III] may afford a useful means of obtaining oily drug,e. g., vitamin E and K1, in an amorphous state. 相似文献
106.
Hayashi K Rahman SM Ohno H Tanaka T Toyooka N Nemoto H Hayashi T 《Chemical & pharmaceutical bulletin》2004,52(8):1015-1017
Herpes simplex virus type 1 thymidine kinase (HSV TK) is involved in both antiherpetic therapy and cancer gene therapy with acyclovir (ACV) and ganciclovir (GCV). Enhanced sensitivity to these drugs is advantageous in their clinical use. In the present study, scopadulciol (SDC) and its related compounds were evaluated for their stimulatory effect on the cytotoxicity of ACV and GCV by determination of selective toxicities against HSV TK-expressing HeLa cells. Although SDC remarkably potenciated the cytotoxicity of ACV and GCV, the other tested compounds showed only weak selectivity, except for compound 34. 相似文献
107.
Fundamental questions in the study of interesting dynamics of planar diffeomorphisms like the Hénon map involve homoclinic phenomena, topological entropy and strange attractors. Inherently, answering these questions requires knowledge about the stable and unstable manifolds, which in the typical case in the plane are smooth curves. We present a method to find highly accurate Taylor Model enclosures of the invariant curves near hyperbolic fixed points. Successive iteration of these local enclosures yields similarly accurate enclosures of pieces of the global manifold tangle. Applications presented include the automatic computation of rigorous enclosures of all homoclinic points up to finite iterates. This allows to find symbolic dynamics in the original system and consequently compute rigorous lower bounds for its topological entropy. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
108.
Structure Determination of an AgI‐Mediated Cytosine–Cytosine Base Pair within DNA Duplex in Solution with 1H/15N/109Ag NMR Spectroscopy
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Dr. Takenori Dairaku Dr. Kyoko Furuita Dr. Hajime Sato Dr. Jakub Šebera Dr. Katsuyuki Nakashima Dr. Jiro Kondo Daichi Yamanaka Prof. Yoshinori Kondo Dr. Itaru Okamoto Prof. Akira Ono Dr. Vladimír Sychrovský Dr. Chojiro Kojima Prof. Yoshiyuki Tanaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(37):13028-13031
The structure of an AgI‐mediated cytosine–cytosine base pair, C–AgI–C, was determined with NMR spectroscopy in solution. The observation of 1‐bond 15N‐109Ag J‐coupling (1J(15N,109Ag): 83 and 84 Hz) recorded within the C–AgI–C base pair evidenced the N3–AgI–N3 linkage in C–AgI–C. The triplet resonances of the N4 atoms in C–AgI–C demonstrated that each exocyclic N4 atom exists as an amino group (?NH2), and any isomerization and/or N4–AgI bonding can be excluded. The 3D structure of AgI–DNA complex determined with NOEs was classified as a B‐form conformation with a notable propeller twist of C–AgI–C (?18.3±3.0°). The 109Ag NMR chemical shift of C‐AgI‐C was recorded for cytidine/AgI complex (δ(109Ag): 442 ppm) to completed full NMR characterization of the metal linkage. The structural interpretation of NMR data with quantum mechanical calculations corroborated the structure of the C–AgI–C base pair. 相似文献
109.
110.
Tadahiko Tsushima Junko Nishikawa Tomohiro Sato Hiroshi Tanida Kazuo Tori Teruji Tsuji Susumu Misaki Masahiro Suefuji 《Tetrahedron letters》1980,21(37):3593-3594
Reductive amination of 3-fluorophenylpyruvic acid was found to give erythro-3-fluorophenylalanine with high selectivity. 相似文献