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991.
A substituted donor–acceptor cyclobutenecarboxamide is synthesized with modest enantiocontrol through a chiral copper(I) complex catalyzed [3 + 1]-cycloaddition reaction of α-acyl diphenylsulfur ylides with 3-siloxy-2-diazo-3-butenamides. With a methyl substituent on the 4-position of the 3-butenamide, the cis-vicinal-3,4-disubstituted cyclobutenecarboxamide is formed with >20:1 diastereocontrol. Donor-acceptor 3-methyl-2-siloxycyclopropenecarboxamide is rapidly formed from the reactant enoldiazoamide and undergoes catalytic ring opening to give only the Z-γ-substituted metallo-enolcarbene. Elimination from 3-siloxy-2-diazo-3-pentenamide to form the conjugated 3-siloxy-2,4-pentadienamide is competitive but minimized at low temperature. 相似文献
992.
Alexander S. Aldoshin Andrey A. Tabolin Sema L. Ioffe Valentine G. Nenajdenko 《Molecules (Basel, Switzerland)》2021,26(12)
The catalyst-free conjugate addition of pyrroles to β-Fluoro-β-nitrostyrenes was investigated. The reaction was found to proceed under solvent-free conditions to form 2-(2-Fluoro-2-nitro-1-arylethyl)-1H-pyrroles. The effectiveness of this approach was demonstrated through the preparation of a series of the target products in a quantitative yield. The kinetics of a conjugate addition of pyrrole was studied in detail to reveal the substituent effect and activation parameters of the reaction. The subsequent base-induced elimination of nitrous acid afforded a series of novel 2-(2-Fluoro-1-arylvinyl)-1H-pyrroles prepared in up to an 85% isolated yield. The two-step sequence herein proposed is an indispensable alternative to a direct reaction with elusive and unstable 1-Fluoroacetylenes. 相似文献
993.
Shicheng Hou Shishao Liang Chao Zhang Yingmei Han Jianhui Liang Hongyu Hu Xingeng Zhang Chun Hu Xiaoping Liu Hong Zhang 《Molecules (Basel, Switzerland)》2021,26(12)
The development of cancer treatments requires continuous exploration and improvement, in which the discovery of new drugs for the treatment of cancer is still an important pathway. In this study, based on the molecular hybridization strategy, a new structural framework with an N-aryl-N’-arylmethylurea scaffold was designed, and 16 new target compounds were synthesized and evaluated for their antiproliferative activities against four different cancer cell lines A549, MCF7, HCT116, PC3, and human liver normal cell line HL7702. The results have shown seven compounds with 1-methylpiperidin-4-yl groups having excellent activities against all four cancer cell lines, and they exhibited scarcely any activities against HL7702. Among them, compound 9b and 9d showed greatly excellent activity against the four kinds of cells, and the IC50 for MCF7 and PC3 cell lines were even less than 3 μM. 相似文献
994.
碳酸钴由于受生产工艺的制约,生产的产品组分复杂,且市售碳酸钴产品的命名也存在多样性。采用X射线荧光光谱仪、电感耦合等离子体发射光谱仪、元素分析仪、X射线多功能粉末衍射仪和红外吸收光谱仪对某碳酸钴产品的成分进行测定和结构表征。结果表明:该碳酸钴产品钴、碳、氮的含量分别为46.53%、8.31%和1.48%,相对标准偏差(RSD)≤3.3%(n=6)。研究新发现了N在碳酸钴产品中以NH+4的形式存在,确认该产品为水合碱式碳酸钴铵[(NH4)1.89Co7.88(CO3)6(OH)6(H2O)4.27]和碳酸钴(CoCO3)的混合物。 相似文献
995.
《Arabian Journal of Chemistry》2021,14(12):103427
This work presents the selective and simultaneous separation of nickel (Ni2+) and gold ([Au(CN)2]−) ions, in trace amounts, from alkaline solution via hollow fiber supported liquid membrane (HFSLM) technique. HFSLM is challengingly carried out in real rinse wastewater generated by the ENIG plating process. The influence of various chemical parameters, including the type of extractant and their concentrations, molar ratios of mixed extractant as well as type of strippant, are also studied. The organophosphorus extractant mixtures of D2EHPA and TBP provide a synergistic effect for target Ni2+ ions but has an antagonistic effect as regards the extraction of non-target [Au(CN)2]− ions. Compared to other inorganic acids, HCl is seen to be the most suitable strippant for the selective stripping. Results demonstrate that percentages of extraction and stripping of Ni2+ ions achieved 85.7 and 83.2%, respectively. In contrast, percentages of extraction and stripping of non-target [Au(CN)2]− ions attained 15.6 and 1.94%. 相似文献
996.
π-Conjugated polymers (CPs) bearing imidazolium and imidazolinium rings in the polymer backbone were prepared from a previously reported monomer, 1,3-bis(2,3-dimethyl-4-bromophenyl)imidazolium chloride, and a newly synthesized monomer, 1,3-bis(2,3-dimethyl-4-bromophenyl)imidazolinium chloride, via Sonogashira and Suzuki–Miyaura coupling reactions. The corresponding model compounds were also synthesized via the same reactions and monomers. The absorption maxima and onset position of the UV–vis spectra of the polymers were observed at longer wavelengths than those of the model compounds, thus revealing the presence of extended π-conjugation along the polymer backbone chain. Both polymers and model compounds were photoluminescent in solution and exhibited solvatochromism. The cast films of the polymers on the Pt and Ag electrodes were demonstrated to be effective catalysts for CO2 electroreduction. 相似文献
997.
The rapidly growing existence of a number of contaminants (i.e. heavy metals, dye compounds, explosives and pesticides etc.) in environment is an alarming concern not only due to their harmful impacts for the environment bur also due to their potential high risk for human health. Thus, the careful and sensitive detection of these environmental contaminants is ver crucial. Electrochemical sensors combined with molecularly imprinted polymers (MIPs) become an attractive area for environmental monitoring. Benefiting from their great features such as high chemical and physical stability, cheap preparation process, excellent selectivity, sensitivity and fast response towards the target compound/s.This review paper aims to present and highlight the latest progresses in the design and development of novel electrochemical sensor systems composed of MIPs and carbon paste electrodes (CPEs) for the sensitive detection of pollutants in environmental samples. 相似文献
998.
S. Rogalsky J.-F. Bardeau S. Makhno O. Tarasyuk N. Babkina T. Cherniavska M. Filonenko K. Fatyeyeva 《Materials Today Chemistry》2021
New hydrophobic protic ionic liquid, 2-butylaminoimidazolinium bis(trifluoromethylsulfonyl)imide (BAIM-TFSI), has been synthesized. The ionic liquid showed good thermal stability to at least 350 °C. The conductivity of BAIM-TFSI determined by electrochemical impedance method was found to be 5.6 × 10?2 S/cm at 140 °C. Homogeneous composite films based on commercial polyimide (PI) Matrimid and BAIM-TFSI containing 30–60 wt% of ionic liquid were prepared by casting from methylene chloride solutions. Thermogravimetric analysis data indicated an excellent thermal stability of PI/BAIM-TFSI composites and thermal degradation points in the temperature range 377 °C–397 °C. The addition of ionic liquid up to 50 wt% in PI films does not lead to any significant deterioration of the tensile strength of the polymer. The dynamic mechanical analysis results indicated both an increase of storage modulus E′ of PI/BAIM-TFSI composites at room temperature and a significant E′ decrease with temperature compared with the neat polymer. The cross-linking of the PI with polyetheramine Jeffamine D-400 allowed to prepare PI/Jeffamine/BAIM-TFSI (50%) membrane with E′ value of 300 MPa at 130 °C. The ionic conductivity of this cross-linked composite membrane reached the level of 10?2 S/cm at 130 °C, suggesting, therefore, its potential use in medium-temperature fuel cells operating in water-free conditions. 相似文献
999.
In this study, a novel flame retardant, that is, amino-terminated phosphorous polyborosiloxane (N-PBSi), was synthesized via a two-step polymerization reaction. The product's chemical structure was characterized firstly by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance, and X-ray photoelectron spectroscopy. It was proved that the prepared N-PBSi was indeed amino terminated and contained multiple flame-retardant elements including P, B, and Si. Besides, based on the variation of its FTIR spectra from room temperature to 700 °C and the subsequent thermogravimetric results, there also showed that the resultant N-PBSi had desirable thermal stability. This is a prerequisite for preparing flame-retardant polymethacrylimide (PMI) as PMI synthesis requires a high temperature treatment process up to 160 °C. On this basis, the condition for N-PBSi synthesis was then optimized to obtain flame retardants with better quality and higher yield. According to the experiments, the reactant ratio and reaction time were recommended to be 1:1.33:3 and 6 h, respectively. To evaluate the effectiveness of N-PBSi further, the flame retardancy of PMI with N-PBSi grafted was then investigated. The UL-94 rating and limiting oxygen index value of the PMI with 15 wt.% of N-PBSi incorporated were tested to be V-0 and 27%, respectively, indicative of greatly enhanced flame-retardant properties. In addition, the flame-retardant mechanism of N-PBSi on PMI was also discussed. Given all of these, the prepared N-PBSi as a reactive and effective flame retardant was promising for PMI. 相似文献
1000.
E.A. Gusakov O.P. Demidov I.O. Tupaeva E.V. Vetrova M.A. Soldatov A.A. Tereshchenko A.D. Dubonosov Y.A. Sayapin A.V. Metelitsa V.I. Minkin 《Materials Today Chemistry》2021
The first representative of a new class of charge transfer complexes for organic semiconductors was synthesized. The reaction of p-nitroaniline (PNA) with [1,10]-phenanthroline-5,6-dione (PD) results in the formation of a stable molecular charge transfer (CT) complex PNA3-PD2 in a ratio of 3:2. The structure of the molecular CT complex PNA3-PD2 was established by X-ray diffraction studies. Using the density functional theory method, it is shown that several types of intermolecular interactions are realized in the complex: between the PNA amino group and the nitro group of another PNA molecule, carbonyl groups, and PD nitrogen atoms. Complex PNA3-PD2 is stable only in solid form. The diffuse reflectance UV–vis spectrum of PNA3-PD2 crystal powder is characterized by the intense weakly structured long-wavelength absorption band up to 650 nm. Quantum chemical calculations of the electronic structure have shown that the complex PNA3-PD2 is a straight-band semiconductor with a band gap of 2.11 eV. 相似文献