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101.
Ryugo S. HAYANO Masaharu TSUBOKURA Makoto MIYAZAKI Hideo SATOU Katsumi SATO Shin MASAKI Yu SAKUMA 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2013,89(4):157-163
The Fukushima Dai-ichi NPP accident contaminated the soil of densely-populated regions in Fukushima Prefecture with radioactive cesium, which poses significant risks of internal and external exposure to the residents. If we apply the knowledge of post-Chernobyl accident studies, internal exposures in excess of a few mSv/y would be expected to be frequent in Fukushima.Extensive whole-body-counter surveys (n = 32,811) carried out at the Hirata Central Hospital between October, 2011 and November, 2012, however show that the internal exposure levels of residents are much lower than estimated. In particular, the first sampling-bias-free assessment of the internal exposure of children in the town of Miharu, Fukushima, shows that the 137Cs body burdens of all children (n = 1,383, ages 6–15, covering 95% of children enrolled in town-operated schools) were below the detection limit of 300 Bq/body in the fall of 2012. These results are not conclusive for the prefecture as a whole, but are consistent with results obtained from other municipalities in the prefecture, and with prefectural data. 相似文献
102.
Shuo Zhang Prof. Dr. Peter H. Seeberger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(69):17444-17451
Acinetobacter baumannii is an opportunistic pathogen that causes serious nosocomial infections. One of the multidrug-resistant strains, AB5075, can result in bacteremia, pneumonia and wound infections associated with high morbidity and mortality. The structurally unique glycans on the surface of these bacteria are attractive targets for the development of glycoconjugate vaccines. Here, we report the first total synthesis of the densely functionalized trisaccharide repeating unit of A. baumannii AB5075 as well as two analogues. The construction of 1,2-cis linkages between the rare sugars relies on a double-serial inversion strategy. The judicious selection of building blocks and reaction conditions allowed for stereoselective glycosylations, the installation of acetamido groups and the (S)-3-hydroxybutanoyl chain. 相似文献
103.
Metabolic study of paeoniflorin and total paeony glucosides from Paeoniae Radix Rubra in rats by high‐performance liquid chromatography coupled with sequential mass spectrometry
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《Biomedical chromatography : BMC》2018,32(4)
A clear understanding of the metabolism of Traditional Chinese Medicines is extremely important in their rational clinical application and effective material foundation research. A novel and reliable strategy was performed to find more metabolites of paeoniflorin, determine the metabolites of total paeony glucosides (TPG) by means of determining those metabolites of paeoniflorin, and compare the metabolism differences between paeoniflorin and TPG by intragastric administration. This strategy was characterized as follows. Firstly, the rats were divided into two groups (the paeoniflorin group and the TPG group) to find differences in metabolism mechanisms between paeoniflorin and TPG. Secondly, UPLC‐FT‐ICR MS and UPLC‐Q‐TOF MS2 were applied to obtain accurate molecular weight and structural information, respectively. Thirdly, the metabolites were tentatively identified by a combination of data‐processing methods including mass defect screening, characteristic neutral loss screening and product ion screening. Finally, a comparative study was employed in the metabolism of paeoniflorin and TPG. Based on the strategy, 18 metabolites of paeoniflorin (including four new compounds) and 11 metabolites of TPG (including two new compounds) were identified. In all of the identified metabolites of paeoniflorin, two metabolites in rat plasma, four metabolites in rat urine and six metabolites in rat feces were found for the first time after paeoniflorin administration. The results indicate that hydrolyzation of the ester bond and glucosidic band and conjugation with glucuronide were the major metabolic pathways of paeoniflorin. The metabolites of paeoniflorin and TPG in rat plasma, urine and feces have been detected for the first time after intragastric administration. The results may contribute to a better understanding of the metabolism mechanism and provide a scientific rationale for researching the material basis of paeoniflorin and TPG in vivo. 相似文献
104.
105.
《Optimization》2012,61(4-5):495-505
This paper investigates properties of the optimality equation and optimal policies in discrete time Markov decision processes with expected discounted total rewards under weak conditions that the model is well defined and the optimality equation is true. The optimal value function is characterized as a solution of the optimality equation and the structure of optimal policies is also given. 相似文献
106.
Ryugo S. HAYANO Ryutaro ADACHI 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2013,89(5):196-199
The first objective data showing the geographical locations of people in Fukushima after the Fukushima Dai-ichi nuclear power plant accident, obtained by an analysis of GPS (Global Positioning System)-enabled mobile phone logs, are presented. The method of estimation is explained, and the flow of people into and out of the 20 km evacuation zone during the accident is visualized. 相似文献
107.
Bernhard Wölfl Dr. Guillaume Mata Prof. Alois Fürstner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(1):255-259
The macrocyclic core of the cytotoxic marine natural product callyspongiolide ( 1 ) was forged by ring-closing alkyne metathesis (RCAM) of an ynoate precursor using a molybdenum alkylidyne complex endowed with triarylsilanolate ligands as the catalyst. This result is remarkable in view of the failed attempts documented in the literature at converting electron deficient alkynes with the aid of more classical catalysts. The subsequent Z-selective semi-reduction of the resulting cycloalkyne by hydrogenation over nickel boride required careful optimization in order to minimize overreduction and competing dehalogenation of the compound's alkenyl iodide terminus as needed for final attachment of the side chain of 1 by Sonogashira coupling. The required cyclization precursor itself was prepared via Kocienski olefination. 相似文献
108.
Sainan Zhang Zhengcai Ju Huida Guan Lu Yu Zhengtao Wang Yuqing Zhao 《Biomedical chromatography : BMC》2019,33(11)
Notoginsenoside R1 (NGR1), a diagnostic protopanaxatriol‐type (ppt‐type) saponin in Panax notoginseng, possesses potent biological activities including antithrombotic, anti‐inflammatory, neuron protection and improvement of microcirculation, yet its pharmacokinetics and metabolic characterization as an individual compound remain unclear. The aim of this study was to investigate the exposure profile of NGR1 in rats after oral and intravenous administration and to explore the metabolic characterization of NGR1. A simple and sensitive ultra‐fast liquid chromatographic–tandem mass spectrometric method was developed and validated for the quantitative determination of NGR1 and its major metabolites, and for characterization of its metabolic profile in rat plasma. The blood samples were precipitated with methanol, quantified in a negative multiple reaction monitoring mode and analyzed within 6.0 min. Validation parameters (linearity, precision and accuracy, recovery and matrix effect, stability) were within acceptable ranges. After oral administration, NGR1 exhibited dose‐independent exposure behaviors with t1/2 over 8.0 h and oral bioavailability of 0.25–0.29%. A total of seven metabolites were characterized, including two pairs of epimers, 20(R)‐notoginsenoside R2/20(S)‐notoginsenoside R2 and 20(R)‐ginsenoside Rh1/20(S)‐ginsenoside Rh1, with the 20(R) form of saponins identified for the first time in rat plasma. Five deglycometabolites were quantitatively determined, among which 20(S)‐notoginsenoside R2, ginsenoside Rg1, ginsenoside F1 and protopanaxatriol displayed relatively high exploration, which may partly explain the pharmacodynamic diversity of ginsenosides after oral dose. 相似文献
109.
Dr. Yusaku Nomura Dr. Frédéric Thuaud Dr. Daisuke Sekine Prof. Dr. Akihiro Ito Satoko Maeda Dr. Hiroyuki Koshino Dr. Daisuke Hashizume Dr. Atsuya Muranaka Dr. Thomas Cruchter Prof. Dr. Masanobu Uchiyama Prof. Dr. Satoshi Ichikawa Prof. Dr. Akira Matsuda Prof. Dr. Minoru Yoshida Prof. Dr. Go Hirai Prof. Dr. Mikiko Sodeoka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(35):8387-8392
A synthetic methodology to access all possible stereoisomers of spectomycin A1 (SMA1) and A2 (SMA2) has been established through late-stage diversification. The key reaction for the construction of all four diastereomers is an intramolecular cyclization based on the umpolung of π-allyl palladium species with bis(pinacolato)diborane (B2(pin)2). Silyl group assisted direct benzylic oxidation of each isomer enabled construction of the fragile β-hydroxytetralone skeleton to provide the SMAs. The relative and absolute stereochemistry of SMA2 was also determined, and the absolute stereochemistry of SMA1 was extrapolated based on the optical rotation of SMA2. The axial chirality of SMAs is discussed based on circular dichroism spectra and DFT calculations, and it is concluded that the M isomer is predominant in solution. Biochemical assessment of all isomers in vitro revealed that the C9 hydroxyl group and dimeric structure were both important for protein SUMOylation-inhibitory activity. 相似文献
110.
Dr. Azusa Kondoh Dipl.‐Chem. Alexander Arlt Barbara Gabor Prof. Alois Fürstner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(24):7731-7738
The lichen‐derived glycoconjugate gobienine A is structurally more complex than most glycolipids isolated from higher plants by virtue of the all‐cis substituted γ‐lactone substructure embedded into its macrocyclic frame. A concise entry into this very epimerization‐prone and hence challenging structural motif is presented, which relies on an enantioselective cyanohydrin formation, an intramolecular Blaise reaction, a palladium‐catalyzed alkoxycarbonylation, and a diastereoselective hydrogenation of the tetrasubstituted alkene in the resulting butenolide. This strategy, in combination with ring‐closing olefin metathesis for the formation of the macrocyclic perimeter, allowed the proposed structure of gobienine A ( 1 ) to be formed in high overall yield. The recorded spectral data show that the structure originally attributed to gobienine A is incorrect and that it is not the epimerization‐prone ester site on the butanolide ring that is the locus of misassignment; rather, the discrepancy must be more profound. 相似文献