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941.
Ahmad Reza Oliaey Asadollah Boshra Sharifah Bee Abdul Hamid 《Heteroatom Chemistry》2015,26(2):150-160
We modeled and studied three types of novel B12C24N12 cages. The structure of these cages was inspired by those of BC2N nanotubes and the B24N24 fulborene skeleton. Density functional theory was used to investigate the various properties of the cages. All three isomers of B12C24N12 were vibrationally stable. The highest occupied molecular orbital‐lowest unoccupied molecular orbital band gap was dependent on the BC2N cage type. The B12C24N12‐II cage was the most favorable nanocage and exhibited a large electric dipole moment. Natural bonding orbital (NBO) analysis confirmed the existence of lone pairs and unoccupied orbitals in the B12C24N12 cages. New donor–acceptor interactions of natural MOs (Molecular Orbitals) were observed in BC2N nanocages. The NBO and atomic polar tensor charges appeared to be fairly well correlated, showing that atomic charges can be obtained at a lower computational cost in this way. 相似文献
942.
Michael E. Kitto Traci A. Menia Douglas K. Haines Shaun E. Beach Clayton J. Bradt Eileen M. Fielman Umme-Farzana Syed Thomas M. Semkow Abdul Bari A. J. Khan 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(1):49-56
An air-sampling network that operates continuously as part of New York State’s environmental surveillance program collected radionuclides emitted as a result of the Fukushima nuclear accident. Samples were collected, typically for 7 days each, by drawing ~600 m3 of air through a particulate-collecting filter followed in series by a canister containing activated charcoal. Additional air sampling was implemented at ~3-day intervals at two locations. Gamma-ray spectroscopy was used to confirm the detection of 131I, 137Cs, 134Cs, and 7Be in the particulate phase at all sites, with maximum concentrations near 1,260, 160, 160, and 5,200 μBq/m3, respectively. Gas-phase 131I, collected on activated charcoal, exhibited a maximum concentration of 3,400 μBq/m3 at the sites. Assessment of radionuclide levels in the air samples suggests that there were minimal health impacts from the airborne radionuclides as the activities contributed an insignificant amount to the annual human dose. 相似文献
943.
Abdul Samad Muhammad Munir Shahid Karam Ahad 《International journal of environmental analytical chemistry》2013,93(14):1446-1458
ABSTRACTA multi-residue method using selected ion monitoring mode GC-MSD has been developed for the quantitative analysis of 30 widely used pesticides in fresh peaches produced in Swat Malakand, Pakistan. The planned methodology involved a sample extraction procedure using liquid-liquid partition with acetonitrile followed by a clean-up step based on solid-phase extraction (SPE). Method validation was performed in accordance with European Union guidelines. The European Union criteria (recovery 70–120%, RSD <20%) were met for majority of pesticides. For most of the pesticides, signal-to-noise ratios were good and background-corrected mass spectra often contained sufficient diagnostic to enable identity and confirmation. The limits of quantification (LOQs) were in the range 0.01–1.0 mg/kg. The above method was successfully applied to the analysis of peach samples (n = 30) from the field. Pesticide concentration in real peach samples was compared with the maximum residue levels (MRLs). Pesticide residues were detected in 73% of the peach samples. Most frequent residues were metalaxyl, α-cypermethrin, azoxystrobin, dimethoate, tebuconazol, λ-cyhalothrin and spiromesifin in peach samples. 相似文献
944.
Jameel Ahmed Baig Abdul Qadir Shah Ghulam Abbas Kandhro Hassan Imran Afridi Sumaira Khan 《International journal of environmental analytical chemistry》2013,93(1):28-42
This study evaluated and interpreted complex data sets of water samples collected from different sampling origins of ground water (hand pump and tube well) and surface water (municipal, river and canal). The aim was to provide information concerning the apportionment of pollution sources to obtain better information about water quality and possible distribution of As with respect to its speciation. The As (III) formed complex with ammonium pyrrolidinedithiocarbamate (APDC) and extracted by surfactant-rich phases in the non-ionic surfactant Triton X-114, while total iAs in water samples was adsorbed on titanium dioxide (TiO2) and determined by electrothermal atomic absorption spectrometry. The accuracy of the proposed methodologies was confirmed by standard addition method. The recoveries of As (III) and total inorganic arsenic (iAs) were found to be >98%. The results revealed that the ground water of the area under study was more contaminated as compared to surface water samples. The mean concentration of As (III) and As (V) in the surface water samples was found to be 15.8 and 6.00?µg?L?1, respectively, whereas, in the case of ground water samples, the contents of As (III) and As (V) ranged from 6.20 to 51.0 and 6.40 to 53.0?µg?L?1, respectively. Principal component analysis performed on a combined (tube well and hand pump) samples data set extracted two significant factors explaining more than 60% of total variance, which suggested that the contamination sources might be natural or anthropogenic. 相似文献
945.
Shumaila Islam Rosly Abdul Rahman Zulkafli Othaman Saira Riaz M. A. Saeed Shahzad Naseem 《Journal of Sol-Gel Science and Technology》2013,68(2):162-168
Owing to the diverse potential applications of hybrid silica–titania thin films, the synthesis and characterization of these films have been carried out with a special focus on application as a medium index layer for multilayered functional coatings. For synthesis, tetraethylorthosilicate and titanium tetraisopropoxide were chosen as precursors for the formation of silica-titania hybrid thin films/nano-composites through an in situ sol–gel process. These films were sequentially obtained on Cu substrate utilizing spin coating. The hybrids were characterized by field emission scanning electron microscope, energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction, atomic force microscopy and Fourier transform infrared spectroscopy (FTIR). Field emission scanning electron microscope morphology displayed a smooth, densified and crack- free layer of silica-titania hybrid nanoparticles in the range of 20–71 nm after calcinations at low temperature of 300ºC for 1 h. X-ray diffraction pattern confirms the phases of titania with higher crystallinity and phase transformation at low temperature. The prepared films were uniform with low 8.852 nm RMS value. The stoichiometry of films was confirmed by EDX results. The FTIR spectroscopy indicated the establishment of heterogeneous chemical bonding between the Ti and Si surfaces through oxygen. 相似文献
946.
JPC – Journal of Planar Chromatography – Modern TLC - A thin-layer chromatographic system comprising of silica gel as stationary phase and 1.0% aqueous urea solution as mobile phase (pH... 相似文献
947.
Fengli Bei Fangfang Jian Xujie Yang Lude Lu Xin Wang Ibrahim Abdul Razak S. Shanmuga Sundara Raj Hoong-Kun Fun 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(1):45-46
In the title compound, [ZnCl2(C14H12N2)2], the environment around the Zn atom is distorted tetrahedral formed by two Cl atoms and two tertiary N atoms of the 2-benzyl-1H-benzimidazole ligands. N—H⃛Cl intermolecular hydrogen bonds link the molecules into infinite chains in the [101] direction. 相似文献
948.
Anwar Usman Ibrahim Abdul Razak Suchada Chantrapromma Hoong‐Kun Fun Tarun K. Sarkar Sankar Basak Gur Dayal Nigam 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(9):1116-1117
In the title compound, C16H19ClN2O4, the pyridine ring is nearly planar, the piperidine ring is non‐planar and the cyclohexane ring adopts a screw‐boat conformation. The carboxylate group makes a dihedral angle of 80.9 (2)° with the least‐squares plane through the cyclohexane ring. 相似文献
949.
Production of High Purity Multi-Walled Carbon Nanotubes from Catalytic Decomposition of Methane 总被引:1,自引:0,他引:1
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Kong Bee Hong Aidawati Azlin Binti Ismail Mohamed Ezzaham Bin Mohd Mahayuddin Abdul Rahman Mohamed Sharif Hussein Sharif Zein 《天然气化学杂志》2006,15(4):266-270
Acid-based purification process of multi-walled carbon nanotubes (MWNTs) produced via catalytic decomposition of methane with NiO/TiO2 as a catalyst is described. By combining the oxidation in air and the acid refluxes, the impurities, such as amorphous carbon, carbon nanoparticles, and the NiO/TiO2 catalyst, are eliminated. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images confirm the removal of the impurities. The percentage of the carbon nanotubes purity was analyzed using thermal gravimetric analysis (TGA). Using this process, 99.9 wt% purity of MWNTs was obtained. 相似文献
950.