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751.
Schlesinger PH Ferdani R Liu J Pajewska J Pajewski R Saito M Shabany H Gokel GW 《Journal of the American Chemical Society》2002,124(9):1848-1849
The design, synthesis, and characterization of a synthetic chloride membrane transporter, SCMTR (synthetic chloride membrane transporter, "scimitar"), are presented. The compound [CH3(CH2)17]2NCOCH2OCH2CO-GGGPGGG-OBzl inserts rapidly into liposomes and planar lipid bilayers. SCMTR has a 1.3 +/- 0.01 nS chloride diffusion pathway (>10:1 Cl/K selectivity). Evidence was also obtained for voltage gating behavior. 相似文献
752.
This paper indicates a simulation analysis for estimating the aluminum (Al) thin film thickness measurements by using the low energy electron beam. In order to calculate the Al thickness estimation, the energy of the incident electron beams was varied from 10 to 30 keV, while the thickness of the Al film was varied between 6 and 14 μm. From the simulation results it was found that electron transmittance fraction in 14 μm sample is about nine orders of magnitude more than 6 μm sample at the same incident electron beam energy. Simulation results show that maximum transmitted electrons versus Al layer thickness has a parabolic relation and by using the obtained equation, it is possible to estimate unknown thickness of the thin film Al layer. All calculations here were done by CASINO numerical simulation package. 相似文献
753.
Mansour Arab Chamjangali Sepideh Soltanpanah Ghadamali Bagherian Amir Hossein Amin 《中国化学会会志》2011,58(1):118-125
A new one‐shot optical cyanide ion sensor is proposed for determination of cyanide ions. The sensor was constructed by immobilizing crystal violet (CV) on triacetylcellulose membrane. The sensing mechanism involves reaction between cyanide ions and the immobilized CV at pH = 5.4, which results in a decrease in absorbance of the membrane at 600 nm. The sensor shows sufficient repeatability, reproducibility, operational lifetime of 3 weeks, and a response of less then 10 min under the optimum conditions and response time of 8 min. Cyanide can be determined in the concentration range of 50.0‐800 μg mL‐1 with a detection limit of 5.0 μg mL‐1. Most ions do not interfere with the determination of cyanide ions. The proposed sensor was successfully applied to the determination of cyanide in spiked water samples. 相似文献
754.
An efficient and convenient method for the oxidation of 1,4‐dihydropyridines mediated by silica gel–supported bis(trimethylsilyl) chromate in refluxing CH2Cl2 is reported. 相似文献
755.
Hossein Ali Mashayekhi Parviz Abroomand-Azar Mohammad Saber-Tehrani 《International journal of environmental analytical chemistry》2013,93(6):516-524
A rapid and sensitive method has been developed for the determination of biphenyl and biphenyl oxide in water samples using dispersive liquid–liquid microextraction followed by gas chromatography. This method involves the use of an appropriate mixture of extraction solvent (8.0?µL tetrachloroethylene) and disperser solvent (1.0?mL acetonitrile) for the formation of cloudy solution in 5.0?mL aqueous sample containing biphenyl and biphenyl oxide. After extraction, phase separation was performed by centrifugation and biphenyl and biphenyl oxide in sedimented phase (5.0?±?0.3?µL) were determined by gas chromatography-flame ionisation (GC-FID) system. Type of extraction and disperser solvents and their volumes, salt effect on the extraction recovery of biphenyl and biphenyl oxide from aqueous solution have been investigated. Under the optimum conditions and without salt addition, the enrichment factors for biphenyl and biphenyl oxide were 819 and 785, while the extraction recovery were 81.9% and 78.5%, respectively. The linear range was (0.125–100?µg L?1) and limit of detection was (0.015?µg?L?1) for both analytes. The relative standard deviation (RSD, n?=?4) for 5.0?µg?L?1 of analytes were 8.4% and 6.7% for biphenyl and biphenyl oxide, respectively. The relative recoveries of biphenyl and biphenyl oxide from sea, river water and refined water (Paksan company) samples at spiking level of 5.0?µg?L?1 were between 85.0% and 100 %. 相似文献
756.
Mohammad Hossein Habibi Reza Mokhtari 《Journal of Thermal Analysis and Calorimetry》2013,112(3):1179-1183
One of the classic methods to extend the spectral response of a wide band gap titania semiconductor to visible light is impurity doping. This study has studied undoped, S-doped, Nb-doped, and S, Nb co-doped titania nanopowders prepared by sol–gel. The relationship between the doping conditions and the thermal stability, phase composition, crystallinity, morphology of particles, and the influence of dopant in similar conditions was investigated. Also the relationship between the dopant and the properties of titania nanosized powders, such as thermal stability, phase composition, crystallinity, morphology and size of particles, was investigated. Thermogravimetry coupled with differential thermogravimetry, X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscope was used for the characterization of the materials. During heating of the air dried samples, their chemical degradation took place giving rise to anatase phase. 相似文献
757.
Hooshang Pirelahi Hossein Rahmani Arash Mouradzadegun Ali Fathi Ali Moudjoodi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):403-404
Photochromism and photoisomerization reactions of some new 2,3,4,4,5,6-hexasubstituted 4H-thiopyrans are described. 相似文献
758.
Hossein Eshghi Parvaneh Shafieyoon 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2149-2152
A facile and efficient method for the preparation of tetrahydropyranyl ethers from alcohols is improved in solvent-free media. These reactions are catalyzed by P2O5 and afford various tetrahydropyranyl ethers in shorter reaction time, with good to excellent yields (75–95%) at room temperature. This method is also compatible with substrates containing acid-sensitive functional groups. 相似文献
759.
Hossein Fakhraian Akbar Mirzaei 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):511-518
A liquid–liquid phase-transfer-catalyzed (PTC) Michaelis-Becker reaction was adopted in the preparation of dialkyl methyl phosphonate (R = Me, iPr, nBu, and iBu). This was performed by the reaction of an appropriate dialkyl hydrogen phosphonate with methyl iodide in the presence of benzyl triethyl ammonium chloride and sodium hydroxide as PTC and base, respectively. A liquid–liquid two-phase system (H2O/CH2Cl2) introduced a suitable situation for the preparation of dialkyl methyl phosphonates with bulky alkyl groups (R = iPr, nBu, and iBu), but with R = Me, the hydrolysis of dimethyl hydrogen phosphonate (reagent) reduced the yield to 22%. In this case, a solid–liquid PTC-free system was successfully applied and yield of over 80% was obtained. 相似文献
760.
Hossein Behniafar 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(4-5):813-827
The direct preparation of various aromatic poly(urea‐imide)s (5a1 –5b4 ) from N‐[3,5‐bis(trimellitimido)phenyl]phthalimide (1) using diphenylphosphoryl azide (DPPA) was investigated. The polymers were obtained by the conversion of imide ring‐containing diacid 1 to corresponding di(carbonyl azide) 2 with DPPA and then to diisocyanate 3 through the Curtius rearrangement of compound 2. This was followed by polyaddition of 3 with two aromatic diamines (4a and 4b). In order to compensate the diisocyanate shortage against the diamines, some excess amounts of the initial triimide‐dicarboxylic acid 1 were used. The molecular weights of the resulting poly(urea‐imide)s were evaluated viscometrically. The poly(urea‐imide)s exhibited an excellent solubility in a variety of polar solvents. The crystallinity nature of the polymers was estimated by means of WXRD. The glass transition temperatures and the 10% wt loss temperatures of the polymers 5a3 and 5b3 were determined by DSC and TGA/DTG methods in nitrogen atmosphere, respectively. The transparent films of the resulting polymers were also prepared by casting the solution. 相似文献