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631.
The binary [24,12,8] Golay code has projection O onto the quaternary [6,3,4] hexacode [9] and the [32,16,8] Reed-Muller code
has projection E onto the quaternary self-dual [8,4,4] code [6]. Projection E was extended to projection G in [8]. In this
paper we introduce a projection, to be called projection Λ, that covers projections O, E and G. We characterise G-projectable
self-dual codes and Λ-projectable codes. Explicit methods for constructing codes having G and Λ projections are given and
several so constructed codes that have best known optimal parameters are introduced.
相似文献
632.
Morteza Sadeghi Ghader Khanbabaei Amir H. Saeedi Dehaghani Mohammad Sadeghi Mohammad A. Aravand Mohammad Akbarzade Somaieh Khatti 《Journal of membrane science》2008
The effect of silica nanoparticles on the gas separation properties of ethylene vinyl acetate (EVA) copolymer containing 28% vinyl acetate has been investigated. The EVA and hybrid EVA–silica membranes were prepared via thermal phase inversion method. Silica nanoparticles prepared by hydrolysis of tetraethylorthosilicate (TEOS), through the sol–gel mechanism. The prepared membranes were characterized using FT-IR, SEM, DSC and XRD methods. FT-IR and SEM results indicated the nanoscale dispersion of silica particles in polymer matrix. As confirmed by XRD and DSC analyses, increasing the silica content enhances the amorphous regions significantly. Gas permeation of EVA–silica nanocomposite membranes with silica contents of 5, 6 and 10 wt.% was studied for N2, O2, CO2 and CH4 single gases at pressures of 4, 6 and 8 bar. The obtained results suggest a significant increase in permeability of all gases and an increase in CO2/N2 and CO2/CH4 gases selectivities upon increasing the silica content. The possible reasons for such behavior were stated and discussed. The pressure dependence of the gas permeabilities of the membranes was also investigated. 相似文献
633.
Mohammad Reza Ganjali Mohammad Reza Pourjavid Mojtaba Shamsipur Taherh Poursaeri Morteza Rezapour Mehran Javanbakht Hashem Sharghi 《Analytical sciences》2003,19(7):995-999
Poly(vinyl chloride) (PVC) based membranes of zinc-phthalocyanine (ZPC) with hexadecyltrimethylammonium bromide (HTAB) as a cation excluder, and dibutyl phthalate (DBP) and benzyl acetate (BA) as plasticizing solvent mediators were prepared and investigated as a SO4(2-) selective electrode. The best performance was observed with a membrane having a composition of ZPC-PVC-HTAB-BA in a ratio of 5%:32%:3%:60%, which works well over a wide concentration range (1.0 x 10(-2) - 1.0 x 10(-6) M) with a Nemstian slope of -29.2 mV per decade of activity, between the pH values of 2.0 to 7.0. This sensor shows a very fast response time of 10 s, and can be used over a period of 2 months with good reproducibility. The proposed sensor displays excellent selectivity for SO4(2-) over a large number of common inorganic anions. The sensor has been successfully applied for the direct and indirect determination of sulfate and zinc in zinc sulfate tablets, respectively. It was also used as an indicator electrode in the potentiometric titration of sulfate ions with barium ions. 相似文献
634.
Inductively coupled plasma mass spectrometry (ICP-MS) has now been developed for application to stable isotope tracer investigations of several minerals/trace elements. Use of this method for such purposes requires an understanding of a number of fundamental issues: analytical chemistry performance of the method of isotopic analysis, relationship of the level of enriched isotope administered to the subject with background level of the isotope already present, the issues of cost, and finally the specific details of the biological issues to be explored.In this paper, a brief discussion of these issues is presented. As an example, the discussion is presented in relation to selected aspects of metabolism of selenium, employing the three stable isotopes74Se,77Se, and82Se in the rat as the biological model.Analytical performance of hydride generation/ICP-MS is discussed for the required analyses of selenium isotopes. It is shown that for solutions containing 10 ng/ml Se of natural isotopic composition, optimized signal/background ratios greater than 40/1 can be obtained, resulting in worst-case detection limits (ng Se) of 2 (74Se), and 0.6 (77,82Se). The precision and accuracy of isotope ratio measurements for the method used routinely in biological studies is 1%. The accuracy of the method for quantitative isotopic analysis is compared with hydride generation/atomic absorption spectrophotometry (HG/AAS). The following results are given (g Se/g or ml; mean + 1 SD,n = 3–5; first HG/ICP-MS, second HG/AAS): SRM 1577a [bovine liver] 0.697 ± 0.002 versus 0.69 ± 0.01; human blood plasma 0.098 ± 0.001 versus 0.135 ± 0.008; human red cells 0.211 ± 0.002 versus 0.216 ± 0.012; and human urine 0.0473 ± 0.0003 versus 0.0489 ± 0.0003.An experiment is described with the rat to show the feasibility of the method for studies of selenium metabolism. Rats were placed on Se-free diet for eight weeks, given their Se requirements in the drinking water in the form of76SeO
3
2–
and a single-day (day 3) replacement of their water with that containing highly enriched74SeO
3
2–
. Isotopic analysis of carcass and selected organs revealed a high degree of isotopic enrichment with respect to74Se during the entire eight weeks of the experiment, indicating the feasibility of this approach for detailed investigations of selenium metabolism in the rat.Presented in part at the 1989 European Winter Conference on Plasma Spectrochemistry, Reutte, Austria 相似文献
635.
Mn(Ⅲ)-四芳基卟啉与高碘酸四丁基铵催化羧酸的氧化脱羧:金属、取代基和轴向阴离子配体的影响 总被引:1,自引:0,他引:1
Gholam Reza KARIMIPOUR Bahador KARAMI Morteza MONTAZEROZOHORI Saeed ZAKAVI 《催化学报》2007,28(11):940-946
锰四芳基卟啉与高碘酸四丁基铵(n-Bu4NIO4)和咪唑(ImH)组合,为羧酸氧化脱羧提供了一个有效的催化剂体系.中位含有吸电子基团和/或大体积芳基的中位-四芳基卟啉使金属卟啉的活性降低.咪唑的存在和金属中心的选择对金属卟啉的催化性能起关键性作用,催化体系中的反离子也有重要影响.Mn(TPP)CN/n-Bu4NIO4/ImH体系的催化活性最好.二苯基乙酸的氧化脱羧可能涉及高价的含氧锰物种与反应物间的相互作用,提出了可能的反应机理. 相似文献
636.
Javad Zolgharnein Hoomayon Tahmasebi Morteza Habibi Saeid Amani 《Journal of inclusion phenomena and macrocyclic chemistry》2004,49(3-4):231-234
The complexation of some alkali and alkaline earth cations with18-crown-6(18C6), dibenzo-18-crown-6 (DB18C6), dicyclohexyl-18-crown-6 (DCY18C6), and dibenzopyridino-18-crown-6 (DBPY18C6) in a methanol solution has been studied by a competitive potentiometric titration using Ag+/Ag electrode as a probe. The stoichiometry and stability constants of the resulting complexes have been evaluated by the MINIQUAD program. The stoichiometry for all resulting complexes was 1:1. The order of stability of Ag+ complexes with desired crown ethers varied as DBPY18C6 > DCY18C6 > 18C6 > DB18C6.The stability of the resulting complexes for each of these crown ethers varies in the order ofK+ > Na+ and Ba2+ > Sr2+ > Ca2+ > Mg2+.For each of the used metal ions the major sequence of the stability constants of the resulting complexes varies as DCY18C6 > 18C6 > DB18C6 > DBPY18C6 with minor exceptions. 相似文献
637.
Photocatalytic degradation of aqueous solution of aniline derivatives such as ortho-nitroaniline (ONA), meta-nitroaniline (MNA), para-nitroaniline (PNA), 4-bromoaniline (4-BrA) and 2-chloroaniline (2-ClA) were carried out over ZnO or TiO2 (anatase and rutile) in a photocatalytic reactor. The observed results revealed that the order of photocatalytic activity for degradation of selected compound was ZnO > TiO2 (rutile) > TiO2 (anatase) with the ratio of the rate constants to the surface area of 3.2 x 10(-3), 1.9 x 10(-3) and 1.0 x 10(-3) respectively. The effect of some physical and chemical parameters such as amount of photocatalyst, pH, time of irradiation and solvent were studied. Degradation kinetic was according to Longmuir behaviour. Spectrophotometric methods and TOC analysis supported that aniline derivatives almost completely mineralized. 相似文献
638.
Josephine Michael Steven B. Larson Morteza M. Vaghefi Roland K. Robins 《Journal of heterocyclic chemistry》1990,27(4):1063-1071
The syntheses of 3-amino-4-methyl-1-(β-D-ribofuranosyl)-1,2,4-triazolin-5-one ( 8a ) and its 2′-deoxy analog 8b as well as 5-amino-2-methyl-1-(β-D-ribofuranosyl)-1,2,4-triazolin-3-one ( 12 ) have been accomplished. Compounds 8a and 8b were synthesized via glycosylation of 3-bromo-5-nitro-1,2,4-triazole which was followed by replacement in three steps of the 3-bromo function to yield 3-nitro-1-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)-1,2,4-triazolin-5-one ( 4a ) and its 2′-deoxy analog 4b . Compounds 4a and 4b were methylated at N2, hydrogenated and deblocked to give 3-amino-4-methyl-1-(β-D-ribofuranosyl)-1,2,4-triazolin-5-one ( 8a ) and the 2′-deoxy analog 8b . Compound 12 was synthesized by glycosylation of 3-amino-1-methyl-1,2,4-triazolin-5(2H)-one ( 10 ). The structures of 8b and 12 were confirmed by single crystal X-ray diffraction analysis. 相似文献
639.
A cloud-point extraction (CPE) process using the nonionic surfactant Triton X-114 to simultaneous extraction and spectrophotometric
determination of Zn(II), Co(II) and Ni(II) from aqueous solution using partial least squares (PLS) regression is investigated.
The method is based on the color reaction of these cations with 1-(2-pyridylazo)2-naphthol and subsequent micelle-mediated
extraction of products. The optimum extraction and reaction conditions such as pH, reagents concentration and effect of time
have been studied. Linearity was obeyed in the range 2–150, 5–250 and 2–150 ng mL−1 of Zn(II), Co(II) and Ni(II) respectively. The relative standard error (RSE) for the simultaneous determination of 15 test
samples of different concentrations of Zn(II), Co(II) and Ni(II) was 4.38%;, 1.18% and 2.42%, respectively. The total relative
standard error (RSEt) for applying the PLS method to 15 synthetic samples in the linear ranges of these metals was 2.36%. The interference effect
of some anions and cations was also tested. The method was applied to the simultaneous determination of Zn(II), Co(II) and
Ni(II) in water and human urine samples. 相似文献
640.
Two spectrophotometric methods are described for the simultaneous determination of binary mixtures of Sn(II) and Sn(IV) in water samples and fruit juice samples, without prior separation steps, using the mean centering of ratio kinetic profiles and partial least squares (PLS) methods. The methods are based on the difference in the rate of the reactions of Sn(II) and Sn(IV) with pyrocatechol violet at pH 4.0. The methods allow rapid and accurate determination of Sn(II) and Sn(IV). The analytical characteristics of the methods for the simultaneous determination of binary mixtures of Sn(II) and Sn(IV) were calculated. The results showed that the methods were capable to simultaneous determination of 0.1–1.80 mg L−1 each of cations. The proposed methods were successfully applied to the simultaneous determination of Sn(II) and Sn(IV)in an orange juice sample. 相似文献