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91.
Lower Activation Energy for Catalytic Reactions through Host–Guest Cooperation within Metal–Organic Frameworks 下载免费PDF全文
Briana Aguila Dr. Qi Sun Xiaoliang Wang Erica O'Rourke Prof. Abdullah M. Al‐Enizi Prof. Ayman Nafady Prof. Shengqian Ma 《Angewandte Chemie (International ed. in English)》2018,57(32):10107-10111
Industrial synthesis is driven by a delicate balance of the value of the product against the cost of production. Catalysts are often employed to ensure product turnover is economically favorable by ensuring energy use is minimized. One method, which is gaining attention, involves cooperative catalytic systems. By inserting a flexible polymer into a metal–organic framework (MOF) host, the advantages of both components work synergistically to create a composite that efficiently fixes carbon dioxide to transform various epoxides into cyclic carbonates. The resulting material retains high yields under mild conditions with full reusability. By quantitatively studying the kinetic rates, the activation energy was calculated, for a physical mixture of the catalyst components to be about 50 % higher than that of the composite. Through the unification of two catalytically active components, a new opportunity opens up for the development of synergistic systems in multiple applications. 相似文献
92.
El-Sawaf Ayman K. West Douglas X. El-Saied Fathy A. El-Bahnasawy Ramadan M. 《Transition Metal Chemistry》1998,23(5):649-655
4–Formylantipyrine N(4)-antipyrinylthiosemicarbazone and its metal complexes have been synthesized and characterized. Elemental analyses, molar conductivities, magnetic measurements and spectral (i.r., electronic, n.m.r., e.s.r.) studies have been used to characterize the complexes. The i.r. spectra show that the thiosemicarbazones behave as bidentate (NS) or tridentate ligands (ONS), either in the thione or thiolato form. Stereochemistries are proposed for the complexes on the basis of both spectral and magnetic studies. 相似文献
93.
Classical trajectory simulations are carried out to investigate the influence of incidence energy, incidence angle, and rotational energy on the penetration of the basal plane (0001) face of ice I(h) by HF at a surface temperature (T(s)) of 150 K. The interaction of HF with ice is modelled by pair interactions, with the pair potential fitted to ab initio (Hartree-Fock+MP2) calculations. The penetration of ice by HF occurs already at very low incidence energies, viz., E(i)>/=20 kJ mol(-1). This is much lower than the threshold incidence energy obtained for penetration of ice by HCl (E(i) approximately 96.5 kJ mol(-1)); the calculated average barrier to penetration of ice by HF is 16.0 kJ mol(-1) and is much lower than that previously reported for HCl. As was the case for HCl, penetration of ice by HF decreases with decreasing incidence energy and increasing incidence angle. Though in general, the penetration probability is independent of the molecule's initial rotational energy, penetration beyond the second bilayer (deep penetration) is suppressed by initial rotation. This suggests that, like was found for HCl, the steering operative in deep penetration is inhibited by initial rotation. Finally, because HF is a weak acid experimental observation of HF penetrated into ice may well be possible using infrared spectroscopy, and we suggest experiments along this line. 相似文献
94.
The structural stability of (trihalomethyl)sulfenyl halides CX3-SX (X is F and Cl) was investigated by DFT-B3LYP and ab initio MP2 calculations using 6-311 + G** basis set. Full energy optimizations were carried out from which the three-fold barrier about C-S bond was calculated to be about 3 kcal mol(-1) in (trifluoromethyl)sulfenyl fluoride and (trifluoromethyl)sulfenyl chloride and about 6 kcal mol(-1) in (trichloromethyl)sulfenyl fluoride and (trichloromethyl)sulfenyl chloride. The vibrational frequencies of the four molecules were computed at the DFT-B3LYP level and the vibrational assignments for the normal modes of the compounds in their ground state structure were made on the basis of normal coordinate calculations and reported experimental data. 相似文献
95.
Awad A. H. Abdel-Ghany Ahmed W. Abd El-Wahab Ayman A. El-Gamasy Ramadan Abdellatif Mohamed Hazem 《Journal of Thermal Analysis and Calorimetry》2020,140(6):2615-2623
Journal of Thermal Analysis and Calorimetry - The purpose of this work is to investigate the opportunity of re-using M&G wastes to get novel PP composites. Recycling of marble and granite... 相似文献
96.
Mohamed M. Elnagar Safia Samir Yasser M. Shaker Ayman A. Abdel‐Shafi Walid Sharmoukh Mohamed S. Abdel‐Aziz Khaled S. Abou‐El‐Sherbini 《应用有机金属化学》2021,35(1)
The synthesis and characterization of Ru (II) terpyridine complexes derived from 4′ functionalized 2,2′:6′,2″‐terpyridine (tpy) ligands are reported. The heteroleptic complexes comprise the synthesized ligands 4′‐(2‐thienyl)‐ 2,2′:6′,2″‐terpyridine) or (4′‐(3,4‐dimethoxyphenyl)‐2,2′:6′,2″‐terpyridine and (dimethyl 5‐(pyrimidin‐5‐yl)isophthalate). The new complexes [Ru(4′‐(2‐thienyl)‐2,2′:6′,2″‐terpyridine)(5‐(pyrimidin‐5‐yl)‐isophthalic acid)Cl2] ( 9 ), [Ru(4′‐(3,4‐dimethoxyphenyl)‐2,2′:6′,2″‐terpyridine)(5‐(pyrimidin‐5‐yl)‐isophthalic acid)Cl2] ( 10 ), and [Ru(4′‐(2‐thienyl)‐2,2′:6′,2″‐terpyridine)(5‐(pyrimidin‐5‐yl)‐isophthalic acid)(NCS)2] ( 11 ) were characterized by 1H‐ and 13C‐NMR spectroscopy, C, H, N, and S elemental analysis, UPLC‐ESI‐MS, TGA, FT‐IR, and UV‐Vis spectroscopy. The biological activities of the synthesized ligands and their Ru (II) complexes as anti‐inflammatory, antimicrobial, and anticancer agents were evaluated. Furthermore, the toxicity of the synthesized compounds was studied and compared with the standard drugs, namely, diclofenac potassium and ibuprofen, using hemolysis assay. The results indicated that the ligands and the complex 9 possess superior anti‐inflammatory activities inhibiting albumin denaturation (89.88–100%) compared with the standard drugs (51.5–88.37%) at a concentration of 500 μg g?1. These activities were related to the presence of the chelating N‐atoms in the ligands and the exchangeable chloro‐ groups in the complex. Moreover, the chloro‐ and thiophene groups in complex 9 produce a higher anticancer activity compared with its isothiocyanate derivative in the complex 11 and the 3,4‐dimethoxyphenyl moiety in complex 10 . Considering the toxicity results, the synthesized ligands are nontoxic or far less toxic compared with the standard drugs and the metal complexes. Therefore, these newly synthesized compounds are promising anti‐inflammatory agents in addition to their moderate unique broad antimicrobial activity. 相似文献
97.
Prof. Christopher M. Burba Kylie Feightner Dr. Ming Liu Prof. Ayman Hawari 《Chemphyschem》2022,23(4):e202100548
Solvate ionic liquid (SIL) synthesis and properties depend on a delicate balancing of cation-solvent and cation-anion interactions to produce materials containing only cation-solvent complexes and solvent-separated anions. Most SILs meeting these characteristics fall within the paradigm of oligomeric ethylene oxides (e.g. glymes and glycols) and lithium salts. Targeted functionalization of solvent molecules to achieve desired properties is a relatively unexplored avenue of research. Fluorinated solvents have significantly different electric charge distributions compared to their nonfluorinated analogs. We test the impact of solvent fluorination for a SIL created from equimolar mixtures of lithium bis(trifluoromethylsulfonyl)imide (LiNTf2) and triethylene glycol (TEG), hereafter [(TEG)1Li]NTf2. In the first experiment, TEG is partially substituted with 2,2,4,4,5,5,7,7-octafluoro-3,6-dioxaoctane-1,8-diol (FTEG). This leads to a precipitous decrease in ionic conductivity and larger quantities of ionically-associated Li(NTf2)2− species, as detected with vibrational spectroscopy. These observations suggest FTEG does not readily coordinate Li+ ions in a manner analogous to TEG. Computational studies reinforce this conclusion. Relative complex cation stabilities are ranked as [(FTEG)1Li]+>[(TEG)1Li]+. A second experiment adds FTEG as a diluent to [(TEG)1Li]NTf2. This places FTEG and TEG in competition to coordinate a limited number of Li+ ions. The resulting mixtures exhibit conductivity enhancement over the parent SIL and minimal changes in ion speciation due to the poor Li+ binding by FTEG compared to TEG. Positron annihilation lifetime spectroscopic studies point to increased amounts of free volume upon dilution of FTEG. This likely explains the origin of the conductivity and viscosity enhancements. 相似文献
98.
Kpotin Gaston A. Bédé Affoué Lucie Houngue-Kpota Alice Anatovi Wilfried Kuevi Urbain A. Atohoun Guy S. Mensah Jean-Baptiste Gómez-Jeria Juan S. Badawi Michael 《Structural chemistry》2019,30(6):2301-2310
Structural Chemistry - Malaria is an important disease causing many death in several countries of Africa and Asia. In these continents, some plants such as Garcinia cola are used to fight against... 相似文献
99.
Seliman Ayman F. Bliznyuk Valery N. DeVol Timothy A. 《Journal of Radioanalytical and Nuclear Chemistry》2017,314(2):743-751
Journal of Radioanalytical and Nuclear Chemistry - The research presented here is the development of sensor materials that are applicable for real-time in situ quantification of radiostrontium in... 相似文献
100.
Mohammed Samar M. Moustafa Ahmed H. El-Sayed Hassan A. Ayman Aya Mohamed Abdussattar S. A. 《Russian Journal of General Chemistry》2022,91(1):S84-S88
Russian Journal of General Chemistry - Functionalization of α-aminopyridine to a new series of pyridine and fused pyridine derivatives has been achieved via its reaction with a variety of... 相似文献