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991.
Maryam Masoori Seyed Mohammad Mahdi Mortazavi Mohammad Vakili 《高分子科学杂志,A辑:纯化学与应用化学》2017,54(3):140-144
The effects of the type and concentration of comonomers 1-hexene and 1-octene in the copolymerization of ethylene were investigated using pre polymerized Ziegler-Natta (catalyst a) and without pre polymerized (catalyst b) catalysts in the presence of hydrogen as a chain transfer agent. The properties of produced polymers were characterized by a set of techniques: (SEM), (EDX), (DSC), (GPC). TIBA and DEAC were used as co catalysts. The results of microscopic and SEM images showed the morphology and structure of catalysts (a) and (b) and the obtained spherical polymers. In the presence of 1-hexene, activity of catalyst (a) was at its maximum. The comonomer 1-octene at 32 mmol presented its activity (1.7 × 103 g polymer/(g cat.h)) and after that, the activities decreased. Copolymerization of ethylene and 1-hexene by catalyst (b) showed higher activity (1.6 × 103 g polymer/ polymer/(g cat.h)) at 40 mmol concentration of 1-hexene in comparison to catalyst (a). 相似文献
992.
Electrochemical Properties of Ag@iron Oxide Nanocomposite for Application as Nitrate Sensor 下载免费PDF全文
Maryam Bonyani Ali Mirzaei Salvatore G. Leonardi Anna Bonavita Giovanni Neri 《Electroanalysis》2015,27(11):2654-2662
Ag@iron oxide nanocomposite powders were synthesized via a two‐step chemical method. Characterization by UV‐Vis, XRD, SEM‐EDX and TEM revealed they are composed of nanosized crystalline silver particles in strict contact with amorphous iron oxide(s). The electrochemical behavior of the synthesized Ag@iron oxide composite was investigated by cyclic voltammetry. Compared with the single phase‐modified electrodes, the Ag@iron oxide/SPCE electrode exhibits an enhanced cathodic current in response to the target analyte, due to a synergistic effect between Ag crystallites and amorphous iron oxide nanoparticles. An amperometric sensor for detection of nitrate based on Ag@iron oxide modified screen‐printed electrode (Ag@iron oxide/SPCE) has been fabricated, showing a good sensitivity (663 µA mM?1 cm?2) and a detection limit of 30 µM. 相似文献
993.
Aurimas Vy?niauskas Maryam Qurashi Nathaniel Gallop Milan Balaz Harry L. Anderson Marina K. Kuimova 《Chemical science》2015,6(10):5773-5778
Viscosity and temperature variations in the microscopic world are of paramount importance for diffusion and reactions. Consequently, a plethora of fluorescent probes have evolved over the years to enable fluorescent imaging of both parameters in biological cells. However, the simultaneous effect of both temperature and viscosity on the photophysical behavior of fluorophores is rarely considered, yet unavoidable variations in temperature can lead to significant errors in the readout of viscosity and vice versa. Here we examine the effect of temperature on the photophysical behavior of three classes of viscosity-sensitive fluorophores termed ‘molecular rotors’. For each of the fluorophores we decouple the effect of temperature from the effect of viscosity. In the case of the conjugated porphyrin dimer, we demonstrate that, uniquely, simultaneous dual-mode lifetime and intensity measurements of this fluorophore can be used for measuring both viscosity and temperature concurrently. 相似文献
994.
Maryam Khezerlou Hadi Goudarzi Samin Asgarifar 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(3):44
Among the potential applications of topological insulators, we theoretically study the coexistence of proximity-induced ferromagnetic and superconducting orders in the surface states of a 3-dimensional topological insulator. The superconducting electron-hole excitations can be significantly affected by the magnetic order induced by a ferromagnet. In one hand, the surface state of the topological insulator, protected by the time-reversal symmetry, creates a spin-triplet and, on the other hand, magnetic order causes to renormalize the effective superconducting gap. We find Majorana mode energy along the ferromagnet/superconductor interface to sensitively depend on the magnitude of magnetization m zfs from superconductor region, and its slope around perpendicular incidence is steep with very low dependency on m zfs . The superconducting effective gap is renormalized by a factor η(m zfs ), and Andreev bound state in ferromagnet-superconductor/ferromagnet/ferromagnet-superconductor (FS/F/FS) Josephson junction is more sensitive to the magnitude of magnetizations of FS and F regions. In particular, we show that the presence of m zfs has a noticeable impact on the gap opening in Andreev bound state, which occurs in finite angle of incidence. This directly results in zero-energy Andreev state being dominant. By introducing the proper form of corresponding Dirac spinors for FS electron-hole states, we find that via the inclusion of m zfs , the Josephson supercurrent is enhanced and exhibits almost abrupt crossover curve, featuring the dominant zero-energy Majorana bound states. 相似文献
995.
Unveiling of Pyrimidindinones as Potential Anti-Norovirus Agents—A Pharmacoinformatic-Based Approach
Oluwakemi Ebenezer Nkululeko Damoyi Maryam A. Jordaan Michael Shapi 《Molecules (Basel, Switzerland)》2022,27(2)
The RNA-dependent RNA polymerase (RdRp) receptor is an attractive target for treating human norovirus (HNV). A computer-aided approach like e-pharmacophore, molecular docking, and single point energy calculations were performed on the compounds retrieved from the Development Therapeutics Program (DTP) AIDS Antiviral Screen Database to identify the antiviral agent that could target the HNV RdRp receptor. Induced-fit docking (IFD) results showed that compounds ZINC1617939, ZINC1642549, ZINC6425208, ZINC5887658 and ZINC32068149 bind with the residues in the active site-B of HNV RdRp receptor via hydrogen bonds, salt bridge, and electrostatic interactions. During the molecular dynamic simulations, compounds ZINC6425208, ZINC5887658 and ZINC32068149 displayed an unbalanced backbone conformation with HNV RdRp protein, while ZINC1617939 and ZINC1642549 maintained stability with the protein backbone when interacting with the residues. Hence, the two new concluding compounds discovered by the computational approach can be used as a chemotype to design promising antiviral agents aimed at HNV RdRp. 相似文献
996.
Peytam Fariba Adib Mehdi Shourgeshty Reihaneh Mohammadi-Khanaposhtani Maryam Jahani Mehdi Imanparast Somaye Faramarzi Mohammad Ali Mahdavi Mohammad Moghadamnia Ali Akbar Rastegar Hossein Larijani Bagher 《Molecular diversity》2020,24(1):69-80
Molecular Diversity - A new series of imidazo[1,2-b]pyrazole derivatives 4a–o was designed, synthesized, and screened for in vitro α-glucosidase inhibitory activity. All compounds showed... 相似文献
997.
Maryam Asachi Mohammadreza Alizadeh Behjani Ehsan Nourafkan Ali Hassanpour 《Particuology》2021,(1):58-68
The effect of particle shape modification on the segregation reduction of enzyme granules in laundry detergent powder mixtures was investigated,both experimentally and computationally using Deseret Element Method(DEM).The shape of modified enzyme particles was in such a way that the large and dense enzyme particles were layered by other fine particles in the detergent powder,by means of a process known in the literature as“seeded granulation”.It is found that the homogeneity of modified enzyme particles could be improved significantly comparing to the original spherical enzyme particles in powder mixtures.Overall,the results of this research demonstrated that the segregation-induced properties of the dense/spherical enzyme particles could be lowered by altering their shape,which could enable the enzyme particles to behave almost similar to other ingredients during the pile formation process. 相似文献
998.
999.
We predict capillary-pressure (drainage) curves in tight-gas sandstones which have little matrix or microporosity using a quantitative grain-scale model. The model accounts for the geometric results of some depositional and diagenetic processes important for porosity and permeability reduction in tight-gas sandstones, such as deformation of ductile grains during burial and quartz cementation. The model represents the original sediment as a dense, disordered packing of spheres. We simulated the evolution of this model sediment into a low-porosity sandstone by applying different amounts of ductile grains and quartz precipitation. A substantial fraction of original pore throats in the sediment is closed by the simulated diagenetic alteration. Because the percolation threshold corresponds to closure of half of the pore throats, the pore space in this type of tight-gas sandstone is poorly connected and is often close to being completely disconnected. The drainage curve for different model rocks was computed using invasion percolation in a network taken directly from the grain-scale geometry and topology of the model. Some general trends follow classical expectations and were confirmed by experimental measurements: increasing the amount of cement shifts the drainage curve to larger pressures. This is related to reduction of the connectivity of pore space resulting from closure of throats. Existence of ductile grains in the ductile grain model also reduces the connectivity of pore space but it treats the throats distribution differently causing the drainage curves to be shifted to larger irreducible water saturation when cement is added to the model. The range of porosities in which these connectivity effects are important corresponds to the range of porosities common for tight gas sandstones. Consequently these rocks can exhibit small effective permeability to gas even at large gas saturations. This problem occurs at larger porosities in rocks with significant content of ductile grains because ductile deformation blocks a significant fraction of pore throats even before cementation begins. Predicted drainage curves agree with measurements on two samples with little microporosity, one dominated by rigid grains, the other containing a significant fraction of ductile grains. We conclude that connectivity of the matrix pore space is an important factor for an understanding of flow properties of tight-gas sandstones. 相似文献
1000.
Naijue Zhu Danielle Lightsey Maryam Foroozesh William Alworth Amit Chaudhary Kristine L. Willett Cheryl L. Klein Stevens 《Journal of chemical crystallography》2006,36(5):289-296
Cytochrome P450 enzymes protect the body from foreign substances through a mechanism that involves oxidation of those substances into more readily excretable polar compounds. It has been shown that some naphthoflavones function as substrates of certain P450 enzymes (CYP1A1 and CYP1B1) and with appropriate structural changes may become inhibitors. Moreover, propargyl ether derivatives of adamantane have been shown to function as selective inactivators of some P450 enzymes (CYP2B1 and CYP2B5). In an attempt to improve the potency and selectivity of inhibition, we have designed and synthesized a series of naphthoflavone propargyl ethers. We report here the synthesis, X-ray crystal structures, and inhibition data (IC50 of EROD inhibition in CYP1A1 and CYP1B1 enzymes) of α-naphthoflavone 2′-propargyl ether, β-naphthoflavone 2′-propargyl ether, α-naphthoflavone 4′-propargyl ether, and β-naphthoflavone 4′-propargyl ether. Crystallographic data: α-naphthoflavone 2′-propargyl ether, , a=7.775(1) ?, b=8.062(1) ?, c=13.110(1) ?, α=84.32(1)°, β=75.42(1)°, γ=86.56(1)°, V=790.8(2) ?3; β-naphthoflavone 2′-propargyl ether, , a=7.605(2) ?, b=7.793(1) ?, c=14.167(2) ?, α=77.06(1)°, β=75.41(1)°, γ=89.54(1)°, V=790.9(2) ?3; α-naphthoflavone 4′-propargyl ether, P21/n, a=14.595(2) ?, b=4.708(1) ?, c=24.745(6) ?, β=106.31(2)°, V=1631.8(7) ?3; β-naphthoflavone 4′-propargyl ether, P1, a=4.8871(5) ?, b= 7.9597(7) ?, c=21.788(3) ?, α=81.771(9)°, β=89.918(10)°, γ=72.223(8)°, V= 797.9(2) ?3. 相似文献