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81.
Quantification of peptides using N‐terminal isotope coding and C‐terminal derivatization for sensitive analysis by micro liquid chromatography‐tandem mass spectrometry 下载免费PDF全文
Yohei Sakaguchi Tomoya Kinumi Akiko Takatsu 《Journal of mass spectrometry : JMS》2016,51(12):1111-1119
Stable isotope‐coding coupled with mass spectrometry is a popular method for quantitative proteomics and peptide quantification. However, the efficiency of the derivatization reaction at a particular functional group, especially in complex structures, can affect accuracy. Here, we present a dual functional‐group derivatization of bioactive peptides followed by micro liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). By separating the sensitivity‐enhancement and isotope‐coding derivatization reactions, suitable chemistries can be chosen. The peptide amino groups were reductively alkylated with acetaldehyde or acetaldehyde‐d4 to afford N‐alkylated products with different masses. This process is simple, quick and high‐yield, and accurate comparative analysis can be achieved for the mass‐differentiated peptides. Then, the carboxyl groups were derivatized with 1‐(2‐pyrimidinyl)piperazine to increase MS/MS sensitivity. Angiotensins I–IV, bradykinin and neurotensin were analyzed after online solid phase extraction by micro LC‐MS/MS. In all instances, a greater than 17‐fold increase in sensitivity was achieved, compared with the analyses of the underivatized peptides. Furthermore, the values obtained from the present method were in agreement with the result from isotope dilution quantification using isotopically labeled angiotensin I [Asp‐Arg‐(Val‐d8)‐Tyr‐Ile‐His‐Pro‐(Phe‐d8)‐His‐Leu]. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
82.
Taito Murakami Dr. Takafumi Yamamoto Dr. Cédric Tassel Dr. Hiroshi Takatsu Dr. Clemens Ritter Prof. Yoshitami Ajiro Prof. Hiroshi Kageyama 《Angewandte Chemie (International ed. in English)》2016,55(34):9877-9880
The NiAs‐type structure is one of the most common structures in solids, but metal order has been almost exclusively limited to chalcogenides. The synthesis of HfMnSb2 is reported with a novel metal‐ordered NiAs‐type structure. HfMnSb2 undergoes a conical spin order below 270 K, in marked contrast to conventional magnetic order observed in NiAs‐type pnictides. We argue that the layered arrangement of Hf and Mn makes it a quasi 2D magnet, where the Mn layers with localized magnetic moments (Mn2+; S=5/2) can interact only through RKKY interactions, instead of metal–metal bonding that is otherwise dominant for typical NiAs‐type pnictides. This result suggests that controlling order–disorder in NiAs‐type pnictides enables a study of 2D‐to‐3D crossover behavior in itinerant magnetic system. 相似文献
83.
A nonenzymatic kinetic resolution of tertiary homoallyl alcohols has been developed through a rhodium-catalyzed retro-allylation reaction under simple conditions. Selectivity factors of up to 12 have been achieved by employing (R)-H8-binap as the ligand, and the reaction can be conducted on a preparative scale. 相似文献
84.
Minematsu T Felder L Oppeneer T Sakazume M Oikawa K Hashimoto T Usui T Kamimura H 《Biomedical chromatography : BMC》2008,22(7):763-769
This paper describes a sensitive and selective liquid chromatography with tandem mass spectrometry (LC-MS/MS) method for determination of the novel survivin suppressant YM155, 1-(2-methoxyethyl)-2-methyl-4,9-dioxo-3-(pyrazin-2-ylmethyl)-4,9-dihydro-1H-naphtho[2,3-d]imidazolium, which is developed for the treatment of solid tumors. This method uses a liquid-liquid extraction from 0.25 mL of dog plasma. LC separation was carried out on a Genesis Silica column (50 mm x 3.0 mm i.d.) at a flow-rate of 0.5 mL/min. Compounds were eluted using a mobile phase of 5 mm ammonium acetate and 0.1% formic acid in water-0.1% formic acid in acetonitrile, 17:83 (v/v). MS/MS detection was carried out with an MDS-Sciex API3000 triple quadrupole mass spectrometer in positive electrospray ionization mode. The standard curve was linear from 0.05 to 50 ng/mL (r > or = 0.9968). The lower limit of quantitation was 0.05 ng/mL. Good intra- and inter-day assay precision (within 7.4% RSD) and accuracy (within +/-12.3%) were obtained. The extraction recovery was 66.2%. The method was successfully applied to preclinical pharmacokinetic studies in dogs. 相似文献
85.
Keishi Ohara Yoshimi Hashimoto Chiaki Hamada Shin-ichi Nagaoka 《Journal of photochemistry and photobiology. A, Chemistry》2008,200(2-3):239-245
The photochemical reactions of vitamin K (VK) with antioxidant vitamins (vitamin E (VE) and vitamin C (VC)) in aqueous hexadecyltrimethylammonium chloride (CTAC), sodium dodecyl sulfate (SDS), and Triton X-100 micelle systems, and in an aerosol OT (AOT) reversed micelle system were investigated by a time-resolved EPR (TR-EPR). The photolysis of VK with VE in the aqueous micelle solutions gave the TR-EPR spectra having strong intensity and net emissive polarization, suggesting that the excited triplet state of VK (3VK*) was rapidly quenched by VE coexisting inside the micelle. On the other hand, the photolysis of VK with VC in the aqueous SDS and CTAC micelle systems gave the spectra having weak intensity, showing that the reaction between 3VK* and VC was inefficient in these micelle systems, probably because 3VK* scarcely diffused out from the micelle. The photolysis of VK with VC in the AOT reversed micelle solution gave the spin-correlated radical pair CIDEP spectrum. The result suggests that the long-lived radical pair was generated from the reaction between 3VK* and VC in the water/oil interface region of the AOT micelle, although one of the reactants dissolved in the oil phase and another did in the separated water phase. 相似文献
86.
Ota T Rontani M Tarucha S Nakata Y Song HZ Miyazawa T Usuki T Takatsu M Yokoyama N 《Physical review letters》2005,95(23):236801
We study electronic configurations in a single pair of vertically coupled self-assembled InAs quantum dots, holding just a few electrons. By comparing the experimental data of nonlinear single-electron transport spectra in a magnetic field with many-body calculations, we identify the spin and orbital configurations to confirm the formation of molecular states by filling both the quantum mechanically coupled symmetric and antisymmetric states. Filling of the antisymmetric states is less favored with increasing magnetic field, and this leads to various magnetic field induced transitions in the molecular states. 相似文献
87.
Sturgeon RE Wahlen R Brandsch T Fairman B Wolf-Briche C Alonso JI González PR Encinar JR Sanz-Medel A Inagaki K Takatsu A Lalere B Monperrus M Zuloaga O Krupp E Amouroux D Donard OF Schimmel H Sejerøe-Olsen B Konieczka P Schultze P Taylor P Hearn R Mackay L Myors R Win T Liebich A Philipp R Yang L Willie S 《Analytical and bioanalytical chemistry》2003,376(6):780-787
The capabilities of National Metrology Institutes (NMIs—those which are members of the Comité Consultatif pour la Quantité de Matière (CCQM)of the CIPM) and selected outside "expert" laboratories to quantitate (C4H9)3Sn+ (TBT) in a prepared marine sediment were assessed. This exercise was sanctioned by the 7th CCQM meeting, April 4–6, 2001, as an activity of the Inorganic Analysis Working Group and was jointly piloted by the Institute for National Measurement Standards of the National Research Council of Canada (NRC) and the Laboratory of the Government Chemist (LGC), UK. A total of 11 laboratories submitted results (7 NMIs, and 4 external labs). Two external laboratories utilized a standard calibration approach based on a natural abundance TBT standard, whereas all NMIs relied upon isotope dilution mass spectrometry for quantitation. For this purpose, a species specific 117Sn-enriched TBT standard was supplied by the LGC. No sample preparation methodology was prescribed by the piloting laboratories and, by consequence, a variety of approaches was adopted by the participants, including mechanical shaking, sonication, accelerated solvent extraction, microwave assisted extraction and heating in combination with Grignard derivatization, ethylation and direct sampling. Detection techniques included ICP–MS (with GC and HPLC sample introduction), GC–MS, GC–AED and GC–FPD. Recovery of TBT from a control standard (NRCC CRM PACS-2 marine sediment) averaged 93.5±2.4% (n=14). Results for the pilot material averaged 0.680±0.015 µmol kg–1 (n=14; 80.7±1.8 µg kg–1) with a median value of 0.676 µmol kg–1. Overall, performance was substantially better than state-of-the-art expectations and the satisfactory agreement amongst participants permitted scheduling of a follow-up Key comparison for TBT (K-28), a Pilot intercomparison for DBT (P-43), and certification of the test sediment for TBT content and its release as a new Certified Reference Material (HIPA-1) with a TBT content of 0.679±0.089 µmol kg–1 (expanded uncertainty, k=2, as Sn) (80.5±10.6 µg kg–1).Electronic Supplementary Material Supplementary material is available in the online version of this article at . 相似文献
88.
Electrorheological effects in carbon, barium titanate, and nickel coated with barium titanate suspensions 总被引:1,自引:0,他引:1
Effects of the electric field on the rheology, electrorheological (ER) effects, are investigated on carbon, barium titanate (BaTiO3) and BaTiO3-coated nickel (BT-Ni) suspensions. Among some electroreological properties, electric field frequency dependence of the induced shear stress (yield stress) observed for three suspensions shows a contrasting behavior. With increase in the electric field frequency, the yield stress decreases above 100 Hz in the carbon suspension, monotonously increases in the BaTiO3 suspension, and is almost constant in the BT-Ni suspension. The difference in the frequency dependence and magnitude of the yield stress is discussed on the basis of the magnitude and relaxation time of the interfacial polarization and the effect of the particle rotation under the shear flow. 相似文献
89.
90.
We have investigated the high-pressure water (H2O) vapor treatment for poly-crystalline Ge (poly-Ge) thin films, which were prepared by solid phase crystallization. The optical-absorption coefficients of poly-Ge were reduced by the treatment, suggesting that the grain-boundary defects were successfully passivated. But the poly-Ge films were sometimes damaged by the treatment in higher pressure and temperature. Compromised conditions should be pursued between the effective passivation and avoiding the damage. The rapid cooling after the treatment promotes defect passivation but causes structural distortion. The results show that the high-pressure H2O vapor treatment is an effective method for the defect passivation of poly-Ge films. 相似文献