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131.
Abstract
The characterization of an optical sensor membrane is described for the determination of tin (II) based on the immobilization of dithizone on a triacetylcellulose membrane. The membrane responds to tin (II) ions by changing color reversibly from green to red in buffer solution at pH 6 and wavelength 611 nm. This optode has a linear range of 0.3–6.33 μg cm−3 (2.52–53.32 μmol dm−3) of Sn2+ ions with a limit of detection of 0.15 μg cm−3 (1.26 μmol dm−3). The response time of the optode was about 8–10 min depending on the concentration of Sn2+ ions. The selectivity of the optode to tin (II) ions at pH 6 was good. The sensor can be readily regenerated by exposure with EDTA solution. The color is fully reversible, and the optical sensor could be fully regenerated. Experimental results showed that the optode could be used as an effective tool in analyzing the tin content in canned foods. 相似文献132.
Majid M. Heravi Samaheh Sadjadi Sodeh Sadjadi Hossein A. Oskooie Rahim Hekmat Shoar Fatemeh F. Bamoharram 《中国化学会会志》2009,56(2):246-250
Silica‐supported Preyssler nanoparticles (H14[NaP5W30O110])/SiO2 are used as a new and recyclable catalyst for the preparation of 1,3‐diaryl‐5‐spirohexahydropyrimidines via a one‐pot condensation of anilines, formaldehyde, and cyclohexanone. 相似文献
133.
Hossein Mahdavi B. O. Mahdi Sadeghzadeh Nader Taheri Qazvini 《Journal of Polymer Science.Polymer Physics》2009,47(5):455-462
The phase behavior of poly(N‐tertbutylacrylamide‐co‐acrylamide) (PNTBAM) in pure water and mixture of water–methanol is studied at different temperatures. The different compositions of PNTBAM are prepared by free‐radical polymerization technique and their phase behavior is studied by turbidimetry. The effects of copolymer and solvent composition on the phase behavior of the copolymers are discussed. It has been suggested that the inhomogenities in polymer chains are responsible for lowering the rate of phase transition by increasing the N‐tertbutylacrylamide (NTBAM) and methanol contents in copolymer and mixture, respectively. For the first time we have revealed that there are second‐order binary interactions in the water–methanol which are dominant in the special range of copolymer composition. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 455–462, 2009 相似文献
134.
An efficient and mild methodology for oxidation of alcohols and polyarenes was described using cetyltrimethylammonium bromochromate (CTMABC) under microwave irradiation. Primary and secondary alcohols and polyarenes could be selectively oxidized under microwave irradiation into the corresponding aldehydes and ketones in high yields and short reaction time, using commercially available and magnetically retrievable oxidative material (CTMABC). 相似文献
135.
Hossein Tavanai Rouholah Jalili Mohamad Morshed 《Surface and interface analysis : SIA》2009,41(10):814-819
The effects of fiber diameter and activation temperature on the pore characteristics of polyacrylonitrile based activated carbon nanofibers are investigated. It was found that lower fiber diameters as well as higher activation temperatures lead to a higher weight loss, specific surface area and total pore volume. The nitrogen adsorption capacity of activated carbon nanofibers is almost three times that of activated carbon fiber with a diameter of 10 µm. As far as the size of pores in activated carbon nanofibers is concerned, it is basically the micropores that dominate the scene. Moreover, tailoring the pore characteristics by adjusting the activation temperature and fiber diameter is plausible. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
136.
137.
Mohammad Kazem Mohammadi Shahriare Ghammamy Soroush Zarrinabadi Mohammad Hossein Farjam Behrang Sabayan 《中国化学》2010,28(11):2199-2203
New orange solid tributylammonium halochromates, (C4H9)3N+CrO3X?, TBAXC (X=F, Cl) are easily synthesized by the reaction of tributylammonium fluoride and chloride with CrO3 in a 1:1 molar ratio in the presence of HF and HCl. Tributylammonium halochromates(VI) are versatile reagent for the effective and selective oxidation of organic substrates. Silica gel supported TBAFC and TBACC are versatile reagents for the effective and selective oxidation of organic substrates, in particular, thiols, under mild conditions. Considerable improvements are observed in the presence of the absorbent, making the work‐up much more convenient. 相似文献
138.
Mohsen Nikpour Hossein Eshtiagh-Hosseini Masoud Mirzaei Amir Aghaei Kaju Soroush Zarinabadi 《中国化学快报》2010,21(4):501-505
<正>A unique ionic hybrid material[C_6H_(12)N_5O]_3[(PO_4)W__(12)O_(36)]·5H_2O has been synthesized from the reaction of((1H-tetrazole-5- yl)methyl)morpholine andα-H_3[(PO_4)W_(12)O_(36)]·21H_2O.It has successfully been characterized by elemental analysis,IR and ~1H NMR spectroscopies,TGA and single-crystal X-ray diffraction method.The title compound is constructed from the three [C_6H_(12)N_5O]~+ cations andα-Keggin[(PO_4)W_(12)O_(36)]~(3-) polyoxoanion.The most remarkable structural feature of this hybrid can be described as two-dimensional inorganic infinite plane-like(2D/∞)[(PO_4)W_(12)O_(36)]~(3-)) which forming via van der Waals interactions along the x axis. 相似文献
139.
Hossein Eshtiagh-Hosseini Mohammad Reza Housaindokht Mohammad Chahkandi Ali Morsali 《Transition Metal Chemistry》2010,35(8):939-947
Abstract
Density functional theory has been used to study the mechanism of bromide oxidation by the oxo-peroxo complex K[VO(O2)Hheida] (heida = N-(2-hydroxyethyl)iminodiacetic acid), which has the highest reported rate constant for bromide oxidation of any vanadium complex. Two possible mechanisms were explored, involving bromide attack on a protonated or unprotonated peroxo atom. The direct nucleophilic attack of bromide on a protonated peroxo begins the reaction, i.e. the protonated peroxo ligand is the active site of reaction. We examined five different transition states in the mechanism. Two transition states were found to have lower activation barriers. A reduction in the potential energy barriers, when calculated using the polarisable continuum model, indicates that with the involvement of acetonitrile as a solvent the transition states become more stable. 相似文献140.
We studied the DFT (B3LYP) and HF at 6-31+G/6-31+G∗∗ levels of theory in order to throw light on the conformation, structure, intramolecular hydrogen bond network, as well as proton and nitrogen NMR (GIAO method) of a series of model primary amides in the gas phase and/or in solution (chloroform, methanol, water, dimethyl sulfoxide, and heptane). In this manner, it was possible to show that the amidic group of these model compounds acts as the H-bond donor and interacts with two different H-bond acceptors, thus stabilizing the C8 pseudocycle. The study was conducted to gain a better understanding of the conformation (both experimentally and theoretically) adopted by hydrazino acetamides (model compounds for aza-β3-peptides). In the light of this, we were able to explain why aza-β3-peptides develop a different H-bond network in comparison to their isosteric β3-peptide analogues (an extension of the β-peptide concept). 相似文献