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161.
Carbon‐based solid acid was used as a new catalyst for conversion of trimethylsilyl ethers to their corresponding ethers in heterogeneous mixtures. The experiments were done moderately at room temperature, and high yields in suitable times were obtained under these conditions. 相似文献
162.
Mohammad Ali Zolfigol Maryam Kiany-borazjani Majid M. Sadeghi Hamid Reza Memarian Iraj Mohammadpoor-baltork 《合成通讯》2013,43(16):2945-2950
A combination of NaHSO4.H2O and NaNO2 in the presence of wet SiO2 was used as an effective oxidizing agent for the oxidation of dihydropyridines to their corresponding pyridine derivatives at room temperature with excellent yields. 相似文献
163.
Piperazine supported on amorphous silica (KG-60-piperazine) as a basic catalyst acts in the Gewald three-component reaction of some aldehydes and ketones with malononitrile as well as ethyl cyanoacetate. The catalyst shows general utility with a variety of starting carbonyl compounds. Moreover, the catalyst can be reused for four additional cycles without significant loss of the activity. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file. 相似文献
164.
A series of three-component reactions has been carried out using HClO4-SiO2 as a versatile heterogeneous catalyst. A series of new and novel N-protected 1-aminoalkyl-2-naphthol derivatives have been prepared under thermal solvent-free reaction conditions. In all cases, the reaction conditions were very simple and high-yielding. 相似文献
165.
Shahnaz Rostamizadeh Ali Mohammad Amani Reza Aryan Hamid Reza Ghaieni Nasrin Shadjou 《合成通讯》2013,43(20):3567-3576
A simple, inexpensive, and efficient one-pot synthesis of 2,3-dihydroquinazoline-4(1H)-one derivatives under solvent-free conditions using a catalytic amount of iodine with excellent product yields is reported. This methodology provides easy, quantitative access to various 2,3-dihydroquinazoline-4(1H)-one derivatives, using commercially available iodine as a catalyst. 相似文献
166.
Mojtaba Shamsipur Hamid Reza Rajabi Mohammad Hassan Beyzavi Hashem Sharghi 《Mikrochimica acta》2013,180(9-10):791-799
We report on the synthesis of polymeric nanoparticles (PNPs) containing a tetrakis(3-hydroxyphenyl)porphyrin, and their use for the separation of mercury(II) ion. The PNPs were prepared by bulk polymerization from methacrylic acid (the monomer), ethyleneglycol dimethacrylate (the cross-linker), 2,2′-azobisisobutyronitrile (the radical initiator) and the mercury(II) complex of 5,10,15,20-tetrakis(3-hydroxyphenyl)-porphyrin. The Hg(II) ion was then removed by treatment with dilute hydrochloric acid. The PNPs were characterized by colorimetry, FT-IR spectroscopy, and scanning electron microscopy. The material is capable of binding Hg(II) from analyte samples. Bound Hg(II) ions can be eluted with dilute nitric acid and then quantified by cold vapor AAS. The extraction efficiency, the effects of pH, preconcentration and leaching times, sample volume, and of the nature, concentration and volume of eluent were investigated. The maximum adsorption capacity of the PNPs is 249 mg g?1, the relative standard deviation of the AAS assay is 2.2 %, and the limit of detection (3σ) is 8 ng.L?1. The nanoparticles exhibit excellent selectivity for Hg(II) ion over other metal ions and were successfully applied to the selective extraction and determination of Hg(II) ion in spiked water samples. Figure
Schematic presentation of leaching process of mercury(II) ion from the prepared IIP 相似文献
167.
Mahmoud Reza Sohrabi Zahra Matbouie Ali Akbar Asgharinezhad Ali Dehghani 《Mikrochimica acta》2013,180(7-8):589-597
We describe a novel magnetic metal-organic framework (MOF) for the preconcentration of Cd(II) and Pb(II) ions. The MOF was prepared from the Fe3O4-pyridine conjugate and the copper(II) complex of trimesic acid. The MOF was characterized by IR spectroscopy, elemental analysis, SEM and XRD. A Box-Behnken design through response surface methodology and experimental design was used to identify the optimal parameters for preconcentration. Extraction time, amount of magnetic MOF and pH value were found to be critical factors for uptake, while type, volume, concentration of eluent, and elution time are critical in the elution step. The ions were then determined by FAAS. The limits of detection are 0.2 and 1.1 μg?L?1 for Cd(II), and Pb(II) ions, respectively, relative standard deviations are <4.5% (for five replicates at 50 μg?L?1 of Cd(II) and Pb(II) ions), and the enrichment capacity of the MOF is at around 190 mg?g?1 for both ions which is higher than the conventional Fe3O4-pyridine material. The magnetic MOF was successfully applied to the rapid extraction of trace quantities of Cd(II) and Pb(II) ions in fish, sediment, and water samples. Figure
Schematic illustration of synthesized magnetic MOF-pyridine nanocomposite 相似文献
168.
Reza Ghiasi Hoda Pasdar 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(6):973-978
The electronic structure and properties of the platinabenzene and para substituted platinabenzenes have been investigated using the hybrid density functional mpw1pw91 theory. The substituent effect in structure parameters, frontier orbital energies, aromaticity indexes, and hyperpolarizability has been studied. The calculations show that, in all molecules HOMO → LUMO transition makes the major contribution in the most intense electronic transition. 相似文献
169.
A one-pot synthesis of 3,5-disubstituted 1,2,4-oxadiazoles with two identical substituents directly from the reaction of nitriles and hydroxylamine hydrochloride in the presence of potassium fluoride as catalyst and solid support under solvent-free condition is described. Moreover, the formation of products has been discussed, and a plausible mechanism has been presented. Simplicity of the process, workup in aqueous media, and excellent yields are some advantages of this method. 相似文献
170.
A novel chiral ionic liquid (CIL) based on nicotinium salt has been synthesized and used as an efficient asymmetric chiral catalyst for reduction of acetophenone derivatives with NaBH4 in methanol at room temperature. The optically active alcohols were obtained in low to moderate enantiomeric excess in a short reaction time. 相似文献