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951.
Dual‐Pore Mesoporous Carbon@Silica Composite Core–Shell Nanospheres for Multidrug Delivery
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Yin Fang Prof. Gengfeng Zheng Jianping Yang Haosha Tang Yafeng Zhang Biao Kong Yingying Lv Prof. Congjian Xu Prof. Abdullah M. Asiri Prof. Jian Zi Prof. Fan Zhang Prof. Dongyuan Zhao 《Angewandte Chemie (International ed. in English)》2014,53(21):5366-5370
Monodispersed mesoporous phenolic polymer nanospheres with uniform diameters were prepared and used as the core for the further growth of core–shell mesoporous nanorattles. The hierarchical mesoporous nanospheres have a uniform diameter of 200 nm and dual‐ordered mesopores of 3.1 and 5.8 nm. The hierarchical mesostructure and amphiphilicity of the hydrophobic carbon cores and hydrophilic silica shells lead to distinct benefits in multidrug combination therapy with cisplatin and paclitaxel for the treatment of human ovarian cancer, even drug‐resistant strains. 相似文献
952.
Carbon Nanotubes Decorated with CoP Nanocrystals: A Highly Active Non‐Noble‐Metal Nanohybrid Electrocatalyst for Hydrogen Evolution
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Qian Liu Dr. Jingqi Tian Wei Cui Dr. Ping Jiang Ningyan Cheng Prof. Abdullah M. Asiri Prof. Xuping Sun 《Angewandte Chemie (International ed. in English)》2014,53(26):6710-6714
The development of effective and inexpensive hydrogen evolution reaction (HER) electrocatalysts for future renewable energy systems is highly desired. The strongly acidic conditions in proton exchange membranes create a need for acid‐stable HER catalysts. A nanohybrid that consists of carbon nanotubes decorated with CoP nanocrystals (CoP/CNT) was prepared by the low‐temperature phosphidation of a Co3O4/CNT precursor. As a novel non‐noble‐metal HER catalyst operating in acidic electrolytes, the nanohybrid exhibits an onset overpotential of as low as 40 mV, a Tafel slope of 54 mV dec?1, an exchange current density of 0.13 mA cm?2, and a Faradaic efficiency of nearly 100 %. This catalyst maintains its catalytic activity for at least 18 hours and only requires overpotentials of 70 and 122 mV to attain current densities of 2 and 10 mA cm?2, respectively. 相似文献
953.
Electrically Controlled Eight‐Spin‐Qubit Entangled‐State Generation in a Molecular Break Junction
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Dr. Mausumi Chattopadhyaya Md. Mehboob Alam Dr. Debasis Sarkar Dr. Swapan Chakrabarti 《Chemphyschem》2014,15(9):1747-1751
The generation of spin‐based multi‐qubit entangled states in the presence of an electric field is one of the most challenging tasks in current quantum‐computing research. Such examples are still elusive. By using non‐equilibrium Green′s function‐based quantum‐transport calculations in combination with non‐collinear spin density functional theory, we report that an eight‐spin‐qubit entangled state can be generated with the high‐spin state of a dinuclear Fe(II) complex when the system is placed in a molecular break junction. The possible gate operation scheme, gating time, and decoherence issues have been carefully addressed. Furthermore, our calculations reveal that the preservation of the high spin state of this complex is possible if the experimentalists keep the electric‐field strength below 0.78 V nm?1. In brief, the present study offers a unique way to realize the first example of a multi‐qubit entangled state by electrical means only. 相似文献
954.
Aftab Aslam Parwaz Khan Anish Khan Abdullah M. Asiri Naved Azum Malik Abdul Rub Sher Bahadar Khan Mohammed M. Rahman Abdulrahman O. Al-Youbi 《Research on Chemical Intermediates》2014,40(4):1703-1714
The mechanism of dismutation of MnO4 2? via the complex [MTZ–MnO4·OH]2?, formed during the oxidation of metronidazole (MTZ), has been investigated spectrophotometrically at different temperatures. The stoichiometry of the reaction is 1:1, i.e. 1 mol MTZ reacts with 1 mol Mn(VII).The reaction is first order in permanganate, less than first order in [MTZ] and [alkali]. The effects of added products and the dielectric constant and ionic strength of the reaction medium were investigated. The main products were identified by spot test and FT-IR. A mechanism involving a free radical has been proposed. In the equilibrium step MTZ binds to the MnO4 ? species to form a complex (C). Investigation of the reaction at different temperatures enabled determination of the activation data for the slow step of proposed mechanism. The proposed mechanism and the derived rate laws are consistent with the observed kinetics. 相似文献
955.
Huda Abdullah Mohd Syafiq Zulfakar Wan Nasarudin Wan Jalal Mohammad Tariqul Islam Sahbudin Shaari 《Journal of Sol-Gel Science and Technology》2014,69(1):183-192
Zinc aluminate compounds have been dispersed in silica matrix prepared by sol-gel method with different compositions for (1 ? x)ZnAl2O4–xSiO2. Continuous stirring of ethylene glycol solution contained zinc nitrate, aluminium nitrate and silicon dioxide to produces gel precursor. Structural and morphological studies of (1 ? x)ZnAl2O4–xSiO2 thin films were examined by field emission scanning electron microscopy (FESEM) and X-ray diffractometer (XRD) analysis. The FESEM images showed the spherical structures with porosity for (1 ? x)ZnAl2O4–xSiO2 thin films. XRD analysis indicated that the crystallite size for (1 ? x)ZnAl2O4–xSiO2 increased from 39.79 to 44.34 nm. Fourier transform infra-red analysis showed that the existence of H2O molecules and the presence of nitrate group within the samples. Dielectric permittivity (ε r ) of (1 ? x)ZnAl2O4–xSiO2 samples were measured within frequency range from 1 Hz to 1 MHz. The dielectric permittivity, ε r decreased as frequency was applied to the sample. The performance of the patch antenna can be measured using return loss analysis. The highest result shows that the patch antenna resonated at frequency 3.46 GHz and gives ?14.25 dB return loss bandwidth. 相似文献
956.
Hitomi Miyamoto Rosnah Abdullah Hayato Tokimura Daichi Hayakawa Kazuyoshi Ueda Shiro Saka 《Cellulose (London, England)》2014,21(5):3203-3215
The dissociation behavior of the crystalline cellulose polymorphs Iβ, II, IIII, and IVI (Cell Iβ, etc.) at 503 K and 100 bar was studied by molecular dynamics simulation, and the mechanism of the experimental liquefaction during treatment with hot-compressed water was elucidated. The results showed that the mini-crystals of Cell Iβ and Cell IVI exhibited similar resistance to dissociation, which implies the occurrence of crystal transformation from Cell IVI to Cell I. On the other hand, the mini-crystal of Cell II gradually dissociated into the water environment with the progress of time in the simulation. The water molecules gradually penetrated the Cell II crystal, especially along the (1 \(\overline{1}\) 0) crystal plane. In contrast, the dissolution behavior differed for the surface and the core areas of the mini-crystal of Cell IIII. The cellulose chains on the surface were dissociated into the water environment, whereas the ordered structure of the chains in the core region was maintained for the entire simulation period. The detailed investigation showed that the core part of Cell IIII was transformed into Cell I at an early stage of the simulation: Cell I is resistant to dissociation of the structure even in the hot-compressed water environment. It can be confirmed that the stability of these four crystals under high temperature and pressure conditions follows the order: Cell II < IIII < IVI ≈ Iβ. 相似文献
957.
RUB MalikAbdul ASIRIAbdullah M KUMAR Dileep AZUM Naved KHAN Farah 《物理化学学报》2014,30(4):699-707
The mixed micellization behavior of an amphiphilic antidepressant drug amitriptyline hydrochloride(AMT)in the presence of the conventional anionic surfactant sodium bis(2-ethylhexyl)sulfosuccinate(AOT)was studied at five different temperatures and compositions by the conductometric technique.The critical micelle concentration(cmc)and critical micelle concentration at the ideal state(cmcid)values show mixed micelle formation between the components(i.e.,drug and AOT).The micellar mole fractions of the AOT(X1)values calculated using the Rubingh,Motomura,and Rodenas models show a higher contribution of AOT in the mixed micelles.The interaction parameter(β)is negative at all temperatures and the compositions show attractive interactions between the components.The activity coefficients(f1and f2)calculated using the different proposed models are always less than unity indicating non-ideality in the systems.TheΔGmΘ values were found to be negative for all the binary mixed systems.However,ΔHmΘ values for the pure drug as well as the drug-AOT mixed systems are negative at lower temperatures(293.15-303.15 K)and positive at higher temperatures(308.15 K and above).TheΔSmΘ values are positive at all temperatures but their magnitude was higher at T=308.15 K and above.The excess free energy of mixing(ΔGex)determined using the different proposed models also explains the stability of the mixed micelles compared to the pure drug(AMT)and surfactant micelles. 相似文献
958.
Md Lutfor Rahman Gurumuthy Hegde Shaheen M. Sarkar Mashitah Mohd Yusoff 《中国化学快报》2014,25(12):1611-1614
The fluorine-substituted benzoate ester rod-shaped liquid crystals containing an azobenzene side chain linked with terminal double bonds were synthesized and characterized.The mesophase and photoswitching properties were determined by polarizing optical microscopy(POM),differential scanning calorimetry(DSC) and UV-visible spectrometry.The rod-shaped compound 4a having an odd number of carbon atoms in the alkyl chains exhibits nematic phase and SmA type phase whereas compound 4b having an even number of carbon atoms showed only nematic phase.Both fluorinecontaining compounds 4c and 4d showed only SmA type phases.The photoswitching properties of these compounds showed a rate of trans to cis isomerization ranging 19-20 s,whereas reverse process took around 230 min in solution.These materials may be ideal in the field of optically rewritable applications where both on and off rates should be crucial. 相似文献
959.
Abdullah?M?Asiri Harry?G?Heller David?S?Hughes Michael?B?HursthouseEmail author John?Kendrick Frank?JJ?Leusen Riccardo?Montis 《Chemistry Central journal》2014,8(1):70
Background
Derivatives of fulgides have been shown to have interesting photochromic properties. We have synthesised a number of such derivatives and have found, in some cases, that crystals can be made to change colour on crushing, a phenomenon we have termed “tribochromism”. We have studied a number of derivatives by X-ray crystallography, to see if the colour is linked to molecular structure or crystal packing, or both, and our structural results have been supported by calculation of molecular and lattice energies.Results
A number of 5-dicyanomethylene-4-diphenylmethylene-3-disubstitutedmethylene-tetrahydrofuran-2-one compounds have been prepared and structurally characterised. The compounds are obtained as yellow or dark red crystals, or, in one case, both. In two cases where yellow crystals were obtained, we found that crushing the crystals gave a deep red powder. Structure determinations, including those of the one compound which gave both coloured forms, depending on crystallisation conditions, showed that the yellow crystals contained molecules in which the structure comprised a folded conformation at the diphenylmethylene site, whilst the red crystals contained molecules in a twisted conformation at this site. Lattice energy and molecular conformation energies were calculated for all molecules, and showed that the conformational energy of the molecule in structure IIIa (yellow) is marginally higher, and the conformation thus less stable, than that of the molecule in structure IIIb (red). However, the van der Waals energy for crystal structure IIIa, is slightly stronger than that of structure IIIb – which may be viewed as a hint of a metastable packing preference for IIIa, overcome by the contribution of a more stabilising Coulomb energy to the overall more favourable lattice energy of structure IIIb.Conclusions
Our studies have shown that the crystal colour is correlated with one of two molecular conformations which are different in energy, but that the less stable conformation can be stabilised by its host crystal lattice.Graphical abstract Graphical representation of the structural and colour change in the tribochromic compound (III).
960.
Md. Musawwer Khan Sumbulunnisan Shareef Sarfaraz Khan Saigal Subash C. Sahoo 《合成通讯》2013,43(21):2884-2894
AbstractAn organo base catalyzed diverse pyrrole-fused 1,4-dihydropyridines were synthesized. This one-pot, three-component domino reaction of enamino imides, aromatic aldehydes, and malononitrile/ethyl cyanoacetate was achieved by 10?mol% of DMAP under refluxing ethanol. In addition, novel bis-pyrrole-fused 1,4-dihydropyridine derivatives were also prepared by using terephthalaldehyde as a linker instead of simple aromatic aldehydes. This transformation proceeds via Knoevenagel condensation/Michael addition and N-cyclization reaction sequence and have some salient features including the use of a cost-effective catalyst, short reaction time and high atom economy. Moreover, the reusability of the catalyst was also performed up to five runs without any significant loss in activity. 相似文献