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51.
A beta-CD-based biodegradable polyrotaxane was prepared by capping both terminals of polypseudorotaxane consisting of hydrazide-terminated PEG-block-PPG-block-PEG (Pluronic P-105) and beta-CD-succinates with mono-aldehyde alpha-CDs. By decreasing pH, the fluorescent intensity of TNS was increased with time, indicating cleavage of the terminal hydrazone bonds followed by beta-CD-succinate release. The terminal alpha-CD moieties of the polyrotaxane are useful for self-assembled formation with some guest molecules. [Diagram: see text] 相似文献
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Mori T. Ikegami T. Yamamura H. Atake T. 《Journal of Thermal Analysis and Calorimetry》1999,57(3):831-838
Y2O3 has a crystal structure of c-type rare-earth oxide. Y2O3 does not show an oxide ionic conductivity. On the other hand, CeO2 based oxide is one of the most interesting of the fluorite oxides since the ionic conductivity of it is higher than that of yttria-stabilized zirconia. However, CeO2 based oxides are partially reduced and develop electronic conductivity under reduced atmosphere.In this study, the effective index for the improvement of ionic conductivity in Y2O3 and CeO2 systems was defined using ionic radii from the viewpoint of crystallography. The utility of this effective index on some electrical properties was investigated.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
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By means of a high pressure d.t.a. method, a new crystalline phase of tetramethylsilane which forms below its melting point has been observed at pressures above 20 MPa. This is a verification of the prediction from earlier calorimetric data at ordinary pressures. 相似文献
57.
Takeshi Saito Toshihide Ihara Tooru Miura Yuuko Yamada Koichi Chiba 《Accreditation and quality assurance》2011,16(8-9):421-428
The accurate quantification of pesticide residues in food is an important factor in assuring the quality of life of our citizens. In general, chromatographic methods are used, which require certified reference materials (CRMs) for each analyte of interest for accurate quantitative analysis. Recently, regulation of pesticides in food, limiting the positive maximum residue (positive list system) has been brought into effect in Japan. Furthermore, ISO/IEC 17025 requires calibration and testing laboratories to program calibrations and measurements traceable to the International System of Units (SI). Accordingly, these laboratories need a suite of CRMs that are traceable to the SI. In order to address these requirements for every analyte of interest in an efficient manner, a new approach to producing SI traceable CRMs is required. Nuclear magnetic resonance (NMR) has been used widely in chemical analysis. One of the well known characteristics of NMR is the proportional relationship between peak area and the number of nuclei contributing to the peak. If accurate relative intensities of peak areas are obtained, this provides an attractive quantitative tool for organic compounds. The area of a signal from an analyte can be measured with respect to another signal originating from a comparator that has been added to the sample solution. The chosen comparator should not react with the analyte or resonate at any chemical shift similar to that of the analyte. This enables us to produce SI traceable CRMs more effectively. In this paper, we demonstrate a new approach for producing CRMs for pesticides using quantitative NMR??an SI traceable quantitative technique. 相似文献
58.
We have prepared a hydrophilic molecularly imprinted polymer (MIP) for the hydrophobic compound bisphenol A (BPA) in aqueous solution using 3-acrylamido-N,N,N-trimethylpropan-1-aminium chloride (AMTC) as the functional monomer. Under redox-polymerization conditions, BPA forms an ion-pair with AMTC, which was confirmed by 1H-NMR titration. The imprinting effect in aqueous solution was evaluated by comparison of this material with the corresponding non-imprinted polymer (NIP) and with a control polymer (CP) bearing no AMTC. The MIP showed the highest activity among the three polymers, and the imprinting factors as calculated from the amount of BPA bound to the MIP divided by the amounts bound to NIP and CP, respectively, are 1.8 and 6.0. The MIP was selective for BPA in aqueous solution, while structurally related compounds are not recognized. Such a selectivity for a hydrophobic compound is rarely observed in aqueous medium because non-specific binding of BPA inevitably leads to hydrophobic interaction. Figure
A hydrophilic molecularly imprinted polymer (MIP) for bisphenol A (BPA) recognition was prepared in aqueous solution. The obtained MIP (BPA-MIP) showed good selectivity under aqueous conditions 相似文献
59.
Hideo Makimura Tooru M Mizuno Jason W Mastaitis Reuven Agami Charles V Mobbs 《BMC neuroscience》2002,3(1):18-6
Background
Several lines of evidence strongly suggest that agouti-related peptide (AGRP) plays a key role in the regulation of metabolic function but ablation of the AGRP gene has no apparent effect on metabolic function. Since specific pharmacological antagonists of AGRP do not presently exist, we assessed if reduction of hypothalamic AGRP mRNA by RNA interference (RNAI) would influence metabolic function, an outcome suggesting that pharmacological antagonists might constitute useful reagents to treat obesity. 相似文献60.
Yoshiya T Taniguchi A Sohma Y Fukao F Nakamura S Abe N Ito N Skwarczynski M Kimura T Hayashi Y Kiso Y 《Organic & biomolecular chemistry》2007,5(11):1720-1730
The O-acyl isopeptide method has recently received attention as an efficient synthetic method for peptides. Herein, forty kinds of "O-acyl isodipeptide unit" Boc-Ser/Thr(Fmoc-Xaa)-OH (1-40) were effectively synthesized in two-steps without epimerization. The O-acyl isodipeptide units are important building blocks to enable the routine use of the O-acyl isopeptide method. 相似文献