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排序方式: 共有120条查询结果,搜索用时 31 毫秒
31.
Ryugo S. HAYANO Masaharu TSUBOKURA Makoto MIYAZAKI Akihiko OZAKI Yuki SHIMADA Toshiyuki KAMBE Tsuyoshi NEMOTO Tomoyoshi OIKAWA Yukio KANAZAWA Masahiko NIHEI Yu SAKUMA Hiroaki SHIMMURA Junichi AKIYAMA Michio TOKIWA 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2015,91(8):440-446
BABYSCAN, a whole-body counter (WBC) for small children was developed in 2013, and units have been installed at three hospitals in Fukushima Prefecture. Between December, 2013 and March, 2015, 2707 children between the ages of 0 and 11 have been scanned, and none had detectable levels of radioactive cesium. The minimum detectable activities (MDAs) for 137Cs were ≤3.5 Bq kg−1 for ages 0–1, decreasing to ≤2 Bq kg−1 for ages 10–11. Including the 134Cs contribution, these translate to a maximum committed effective dose of ∼16 µSv y−1 even for newborn babies, and therefore the internal exposure risks can be considered negligibly small.Analysis of the questionnaire filled out by the parents of the scanned children regarding their families’ food and water consumption revealed that the majority of children residing in the town of Miharu regularly consume local or home-grown rice and vegetables, while in Minamisoma, a majority avoid tap water and produce from Fukushima. The data show, however, no correlation between consumption of locally produced food and water and the children’s body burdens. 相似文献
32.
Hisayuki Horai Masanori Arita Shigehiko Kanaya Yoshito Nihei Tasuku Ikeda Kazuhiro Suwa Yuya Ojima Kenichi Tanaka Satoshi Tanaka Ken Aoshima Yoshiya Oda Yuji Kakazu Miyako Kusano Takayuki Tohge Fumio Matsuda Yuji Sawada Masami Yokota Hirai Hiroki Nakanishi Kazutaka Ikeda Naoshige Akimoto Takashi Maoka Hiroki Takahashi Takeshi Ara Nozomu Sakurai Hideyuki Suzuki Daisuke Shibata Steffen Neumann Takashi Iida Ken Tanaka Kimito Funatsu Fumito Matsuura Tomoyoshi Soga Ryo Taguchi Kazuki Saito Takaaki Nishioka 《Journal of mass spectrometry : JMS》2010,45(7):703-714
MassBank is the first public repository of mass spectra of small chemical compounds for life sciences (<3000 Da). The database contains 605 electron‐ionization mass spectrometry(EI‐MS), 137 fast atom bombardment MS and 9276 electrospray ionization (ESI)‐MSn data of 2337 authentic compounds of metabolites, 11 545 EI‐MS and 834 other‐MS data of 10 286 volatile natural and synthetic compounds, and 3045 ESI‐MS2 data of 679 synthetic drugs contributed by 16 research groups (January 2010). ESI‐MS2 data were analyzed under nonstandardized, independent experimental conditions. MassBank is a distributed database. Each research group provides data from its own MassBank data servers distributed on the Internet. MassBank users can access either all of the MassBank data or a subset of the data by specifying one or more experimental conditions. In a spectral search to retrieve mass spectra similar to a query mass spectrum, the similarity score is calculated by a weighted cosine correlation in which weighting exponents on peak intensity and the mass‐to‐charge ratio are optimized to the ESI‐MS2 data. MassBank also provides a merged spectrum for each compound prepared by merging the analyzed ESI‐MS2 data on an identical compound under different collision‐induced dissociation conditions. Data merging has significantly improved the precision of the identification of a chemical compound by 21–23% at a similarity score of 0.6. Thus, MassBank is useful for the identification of chemical compounds and the publication of experimental data. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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34.
Ninomiya K Kurita T Hohsaka T Sisido M 《Chemical communications (Cambridge, England)》2003,(17):2242-2243
A simple and versatile method for aminoacylation of a dinucleotide (pdCpA) in aqueous micellar solution was developed by using a hydrophobic amino acid derivative, N-pentenoyl-L-2-naphthylalanine cyanomethyl ester (Pen-napAla-OCM), and a CTACl micelle. 相似文献
35.
Fukuzumi S Inada O Satoh N Suenobu T Imahori H 《Journal of the American Chemical Society》2002,124(31):9181-9188
4-Acetyl-N,N-diisopropyl-1-benzylnicotinamidinium ion (ABNA(+)) and 1-benzyl-4-phenylnicotinamidinium ion (PhBNA(+)) were newly synthesized as NAD(+) analogues to examine the electron-transfer reactivity and the effects of metal ions on the reactivity in comparison with those of 1-benzylnicotinamidinium ion (BNA(+)) and 1-methyl-4-phenylpyridinium ion (MPP(+)) which has no amide or acetyl group. A remarkable positive shift in the one-electron reduction potential of ABNA(+) was observed in the presence of Sc(3+) which forms a 1:1 complex with ABNA(+) through both acetyl and amide groups, whereas no such shift in the presence of Sc(3+) was observed for the one-electron reduction of MPP(+) which has no acetyl or amide group. Similar but less positive shifts in the one-electron reduction potentials were observed in the presence of Sc(3+) for the one-electron reduction of BNA(+) and PhBNA(+) both of which have only one amide group. The rate of electron-transfer reduction of ABNA(+) is enhanced significantly by the complexation with Sc(3+) to produce stable ABNA(*)-Sc(3+) complex which has been successfully detected by ESR. The electron self-exchange rates of the MPP(*)/MPP(+) system have been determined from the ESR line width variation and are compared with those of the ABNA(*)/ABNA(+) system. 相似文献
36.
Qualitative and quantitative analysis of amino acids by capillary electrophoresis-electrospray ionization-tandem mass spectrometry 总被引:2,自引:0,他引:2
We describe a method to identify and quantify amino acids using capillary electrophoresis-electrospray ionization-triple-quadrupole tandem mass spectrometry (CE-ESI-MS/MS). Amino acids, including physiological amino acids, were first separated by CE under acidic pH conditions and then detected by MS/MS. To efficiently introduce the whole sample into the capillary, no electrical potential was applied to the electrospray probe until running electrophoresis. The position of the electrosprayer with respect to the MS capillary entrance drastically affected sensitivity and generation of cluster ions. MS/MS with multiple reaction monitoring (MRM) detection was performed to obtain sufficient selectivity and sensitivity. Under optimized CE-MS/MS conditions, the minimum detectable levels for 32 free amino acids normally found in proteins and other physiological amino acids were between 0.1 and 14 micromol/L with pressure injection of 50 mbar for 3 s (3 nL) at a signal-to-noise ratio of 3. For most amino acids, this constitutes a severalfold increase in sensitivity compared to CE-MS. The relative standard deviations (% RSD) for all amino acids were better than 0.4% for migration times and between 1.4% and 8.6% for peak areas (n = 10). Since amino acids exhibited characteristic MS/MS spectra, this approach is useful for the simultaneous, selective, quantitative, and reproducible analysis of amino acids in physiological and biological samples that contain various kinds of matrices. The power of the method was demonstrated by analyzing amino acids in human urine. 相似文献
37.
Yoshihisa Kurasawa Tomoyoshi Hosaka Atsushi Takada Ho Sik Kim Yoshihisa Okamoto 《Journal of heterocyclic chemistry》1994,31(6):1661-1665
The 3-(arylhydrazono)methyl-2-oxo-1,2-dihydroquinoxalines 1a-e and 2a-i showed tautomeric equilibria between the hydrazone imine A and diazenyl enamine B forms in dimethyl sulfoxide media. The sub-stituent effects on the tautomer ratios of A to B in compounds 1a-e and 2a-i were studied by the nmr spec-troscopy. The electron-donating or electron-withdrawing p-substituents R1 in compounds 2a-i represented a tendency to increase the ratios of the tautomer A or the tautomer B , respectively, exhibiting the linear correlation of the Hammett constants σp (-0.17 to +0.78) with the tautomer ratios of A to B or the tautomeric equilibrium constants KT. However, the presence of the ester group R2 in compounds 1a-e induced the exclusive existence of the tautomer A regardless of the nature of the p-substituents R1. In the tautomeric thermodynamic study, the elevating temperature increased the ratios of the hydrazone imine tautomer A in compounds 2a-i . The tautomeric thermodynamic parameters ΔG°, ΔH° and ΔS° were derived from the van't Hoff plots for compounds 2a , b , h , i , wherein the entropy term dominated the free-energy difference between the A and B tautomers. 相似文献
38.
Ikuo Nakanishi Shinobu Itoh Tomoyoshi Suenobu Shunichi Fukuzumi 《Angewandte Chemie (International ed. in English)》1998,37(7):992-994
The redox behavior of “active aldehydes” 1 − derived from 3-benzylthiazolium salts and simple aldehydes in the presence of a base has been examined with low-temperature cyclic voltammetry and EPR spectroscopy. The highly negative oxidation potentials of 1 − and the spin distribution of the intermediate radicals 1 . indicate that the active aldehyde can act as an efficient electron mediator in thiamin-dependent enzymatic redox systems. 相似文献
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40.
Bridged Stilbenes: AIEgens Designed via a Simple Strategy to Control the Non‐radiative Decay Pathway
Riki Iwai Satoshi Suzuki Shunsuke Sasaki Amir Sharidan Sairi Kazunobu Igawa Tomoyoshi Suenobu Keiji Morokuma Gen‐ichi Konishi 《Angewandte Chemie (International ed. in English)》2020,59(26):10566-10573
To broaden the application of aggregation‐induced emission (AIE) luminogens (AIEgens), the design of novel small‐molecular dyes that exhibit high fluorescence quantum yield (Φfl) in the solid state is required. Considering that the mechanism of AIE can be rationalized based on steric avoidance of non‐radiative decay pathways, a series of bridged stilbenes was designed, and their non‐radiative decay pathways were investigated theoretically. Bridged stilbenes with short alkyl chains exhibited a strong fluorescence emission in solution and in the solid state, while bridged stilbenes with long alkyl chains exhibited AIE. Based on this theoretical prediction, we developed the bridged stilbenes BPST[7] and DPB[7], which demonstrate excellent AIE behavior. 相似文献