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991.
Xiaoyan Deng Guihong Liao Qingwu Long Yujiao Gao Hao Peng Hongwu He 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):663-671
Abstract A series of [(substituted phenoxyacetoxy)(substituted phenyl)methyl](methyl)phos- phinates containing fluorine were designed and synthesized. All the synthesized compounds were identified by elemental analysis, IR, 1H NMR, mass spectrometry. O-methyl [(2-fluorophenoxyacetoxy)(2,4-dichlorophenyl)methyl](methyl)phosphinate was further analyzed by X-ray single-crystal diffraction. Their herbicidal activity against a set of weed species was examined. Some of the compounds showed potential herbicidal activity, which provided some indications for further studies on structure modification. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献
992.
Ling Gao Xiaoyan Deng Xiaosong Tan Qingwu Long Hao Peng Hongwu He 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):989-994
Abstract A series of 2-methylpropan-2-aminium methyl 1-(substituted phenoxyacetoxy) alkylphosphonates were selectively synthesized by reacting the corresponding dimethyl 1-(substitutedphenoxyacetoxy)alkylphosphonates with an excess of 2-methylpropan-2-amine. All the title compounds were identified by IR, 1H NMR, and 31P NMR, some of them were further analyzed by 19F NMR and 13C NMR. Their herbicidal activity was investigated and the results showed that most of the demethylated aminium salts exhibited notable herbicidal activities against Brassica napus L. and Echinochloa crusgalli. Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional text, figures and tables. 相似文献
993.
994.
AbstractIn this work, an effective method was developed to prepare novel PEO-b-PPO-b-PEO (EPE)/α-cyclodextrin (α-CD) supramolecular hydrogels containing exfoliated graphite nanoplates (xGNPs) by mixing an aqueous solution of α-CD with an aqueous dispersion of xGNPs at the presence of amphiphilic EPE copolymer. The EPE copolymer played three important roles in the preparation process: (1) as an exfoliating agent to break expanded graphites into xGNPs under ultrasonication, (2) as a dispersant to stabilize xGNPs in the aqueous solution, and (3)as a component to form the inclusion complexes with α-CD. The resultant xGNPs/EPE/α-CD hybridized hydrogels were characterized by scanning electron microscopy, wide-angle X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopy, which confirmed not only the formation of supramolecular hydrogel structure but also the homogenous dispersion of xGNPs in the hydrogel matrix. It was found that the existence of xGNPs can accelerate the speed of gel formation in comparison with that of the native EPE/α-CD hydrogel. Additionally, the water-retention ability and the release behavior of vancomycin hydrochloride for the xGNPs/EPE/α-CD hybridized hydrogels were investigated. 相似文献
995.
The flammability and the thermal oxidative degradation kinetics of expandable graphite (EG) with magnesium hydroxide (MH) in flame‐retardant polypropylene (PP) composites were studied by limiting oxygen index (LOI), UL‐94 test, and thermogravimetric analysis (TGA). The results show that EG is a good synergist for improving the flame retardancy of PP/MH composite and the effect is enhanced with decreasing EG particle size. The Kissinger method and Flynn‐Wall‐Ozawa method were used to determine the apparent activation energy (E) for degradation of PP and flame retarded PP composites. The data obtained from the TGA curve indicate that EG markedly increases the thermal degradation temperature of PP/MH composites and improves the thermal stability of the composites. The kinetic results show that the values of E for degradation of flame retarded PP composites is much higher than that of neat PP, especially PP/MH composites with suitable amount of EG, which indicates that the flame retardants used in this work have a great effect on the mechanisms of pyrolysis and combustion of PP. 相似文献
996.
Lan-Hua Wei Yong-Bing He Jin-Long Wu Xiao-Jun Wu Ling-Zhi Meng Xi Yang 《Supramolecular chemistry》2013,25(8):561-567
Two colorimetric thiourea-based chemsensors with two relatively rigid arms, 2A and 2B, were synthesized. Their binding abilities with halide anions, AcO?, [Formula: See Text] were studied by UV-Vis spectroscopy in DMSO. The two sensors showed a notable selective color response to F? anion from colorless to green-yellow in recognition. The structures of the two sensors and their binding behaviors are discussed. The association constants were calculated by nonlinear fittings of 1:1, 1:2 or 1:1 to 1:2. 相似文献
997.
Chunxiao Lv Qing Li Yaowen Zhang Zhenyu Sui Bosai He Huarong Xu Yidi Yin Xiaohui Chen Kaishun Bi 《Journal of mass spectrometry : JMS》2013,48(8):904-913
A fast, sensitive and reliable ultra fast liquid chromatography‐tandem mass spectrometry (UFLC‐MS/MS) method has been developed and validated for simultaneous quantitation of polygalaxanthone III (POL), ginsenoside Rb1 (GRb1), ginsenoside Rd (GRd), ginsenoside Re (GRe), ginsenoside Rg1 (GRg1) and tumulosic acid (TUM) in rat plasma after oral administration of Kai‐Xin‐San, which plays an important role for the treatment of Alzheimer's disease (AD). The plasma samples were extracted by liquid–liquid extraction using ethyl acetate–isopropanol (1:1, v/v) with salidrdoside as internal standard (IS). Good chromatographic separation was achieved using gradient elution with the mobile phase consisting of methanol and 0.01% acetic acid in water. The tandem mass spectrometric detection was performed in multiple reaction monitoring mode on 4000Q UFLC‐MS/MS system with turbo ion spray source in a negative and positive switching ionization mode. The lower limits of quantification were 0.2–1.5 ng/ml for all the analytes. Both intra‐day and inter‐day precision and accuracy of analytes were well within acceptance criteria (±15%). The mean absolute extraction recoveries of analytes and IS from rat plasma were all more than 60.0%. The validated method has been successfully applied to comparing pharmacokinetic profiles of analytes in normal and AD rat plasma. The results indicated that no significant differences in pharmacokinetic parameters of GRe, GRg1 and TUM were observed between the two groups, while the absorption of POL and GRd in AD group were significantly higher than those in normal group; moreover, the GRb1 absorbed more rapidly in model group. The different characters of pharmacokinetics might be caused by pharmacological effects of the analytes. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
998.
Moisture absorption and diffusion behavior of an underfill material used for electronic packaging with a glass transition temperature (T g) slightly above room temperature have been investigated by the sorption thermogravimetric analysis technique. It has been found that moisture diffusion in this material follows the Fick’s diffusion model, and moisture absorption–desorption is reversible and repeatable. Based on moisture-induced mass gain versus time curve, the diffusion constant can be determined. It was found that below T g, moisture diffusivity exhibits an Arrhenius temperature dependence, which changes to a different Arrhenius temperature dependence as the temperature increases to T > T g. The change in diffusivity from T < T g to T > T g is accompanied by a significant decrease in the energy barrier for moisture diffusion. Results shed light on the change in moisture diffusion in polymer-based materials in the glassy and the rubbery state. 相似文献
999.
Comparative investigations of LiVPO4F/C and Li3V2(PO4)3/C synthesized in similar soft chemical route
Jiexi Wang Zhixing Wang Xinhai Li Huajun Guo Wei Xiao Silin Huang Zhenjiang He 《Journal of Solid State Electrochemistry》2013,17(1):1-8
Triclinic LiVPO4F and monoclinic Li3V2(PO4)3 are synthesized through a soft chemical process with mechanical activation assist, followed by annealing. In this process, ascorbic acid is used as reducing agent as well as carbon source. The as-prepared samples are coated with amorphous carbon. XPS analysis results show the expected valency states of ions in LiVPO4F and Li3V2(PO4)3. The electrochemical properties of the prepared LiVPO4F/C and Li3V2(PO4)3/C cathodes are evaluated. The as-prepared LiVPO4F/C cathode shows an initial discharge specific capacity of 140?±?3 mAh?g?1 at 30 mA?g?1 in the voltage range of 3.0~4.4 V, compared with that of 138?±?3 mAh?g?1 possessed by Li3V2(PO4)3/C. Both samples exhibit good cycle performance at different current densities. The capacity delivered by LiVPO4F remains 95.5 and 91.7 % of its initial discharge capacity after 50 cycles at 150 and 750 mA?g?1, respectively, while 97.4 and 90.6 % for Li3V2(PO4)3/C. But the rate capability of LiVPO4F/C is not so good compared with as-prepared Li3V2(PO4)3/C. 相似文献
1000.
Min Huang Wen-Jing Chen Ying Zhou Ru Feng Jie Fu Jing-Yi Ma Xiang-Shan Tan Chi-Yu He Qi-Ming Zhang Wen-Yi He Yu-Lin Deng Yu-Kui Zhang Xian-Feng Zhang Yan Wang 《中国化学快报》2013,24(9):840-844
The chiral separations of four pharmaceutical racemates which contain N-alkyl groups were satisfactorily resolved using SBE-β-CD as a chiral mobile phase additive(CMPA)in a RP-HPLC system(the resolution is 2.701 for ondansetron hydrochloride,1.996 for sulpiride,1.293 for clenbuterol hydrochloride and 0.816 for omeprazole).In addition,the effects of different parameters such as CD type and CD concentration were investigated.The separation mechanism arises through the combination of several potential interactions,including electrostatic interactions as well as hydrogen bonding interactions and hydrophobic inclusion interactions,which allow for the SBE-β-CD–drug complexation with strong stereoselectivity and stability.The resolution also relates to the number and location of N atoms in the enantiomers.This method will be applicable to the isolation of various types of biologically important enantiomers containing N-alkyl groups. 相似文献