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61.
Examining metal nanoparticle surface chemistry using hollow-core, photonic-crystal, fiber-assisted SERS 总被引:1,自引:0,他引:1
In this Letter, we demonstrate the efficacy of hollow core photonic crystal fibers (HCPCFs) as a surface-enhanced Raman spectroscopy (SERS) platform for investigating the ligand exchange process on the surface of gold nanoparticles. Raman measurements carried out using this platform show the capability to monitor minute amounts of surface ligands on gold nanoparticles used as an SERS substrate. The SERS signal from an HCPCF exhibits a tenfold enhancement compared to that in a direct sampling scheme using a cuvette. Using exchange of cytotoxic cetyltrimethylammonium bromide with α-methoxy-ω-mercaptopoly(ethylene glycol) on the surface of gold nanorods as an exemplary system, we show the feasibility of using HCPCF SERS to monitor the change in surface chemistry of nanoparticles. 相似文献
62.
M.S. Attia A.O. Youssef Amr A. Essawy M.S.A. Abdel-Mottaleb 《Journal of luminescence》2012,132(10):2741-2746
Highly luminescent complexes of Eu and Tb ions with norfloxacin (NFLX) and gatifloxacin (GFLX) were prepared in sol–gel matrix. The red and green emissions of Eu and Tb ions were obtained by the energy transfer from the triplet state of (NFLX) and (GFLX) to the excited emitting states (5D0 and 5D4) of Eu and Tb, respectively. The intensity of the electric field emission bands (5D0→7F2, 617 nm and 5D4→7F5, 545 nm) of Eu and Tb ions were proportional to the concentration of (NFLX at pH 6.0) and (GFLX at pH 3.5) in acetonitrile with excitation wavelengths (λex) (340 and 395) and (370 and 350 nm) for Eu and Tb ions, respectively. The monitored luminescence intensity of the system showed a good linear relationship with the concentration of NFLX within a range of 5×10?9–5.8×10?6 and 5×10?8–1.0×10?6 mol L?1 with a correlation coefficient of 0.990, and for GFLX within a range of 2.4×10?9–3.2×10?5 and 5×10?8–8.0×10?6 mol L?1 with a correlation coefficient of 0.995. The detection limit (LOD) was determined as 3.0×10?9 and 1.0×10?8 mol L?1 for NFLX and 1.6×10?10 and 2.0×10?8mol L?1 for GFLX. The limit of quantification (LOQ) is 9×10?9 and 3.0×10?8 and 4.8×10?10 and 6.0×10?8 in case of Eu and Tb, respectively. 相似文献
63.
Two methods for the preparation of uniform dispersions of dehydrocholic acid of different morphologies are described. In the first case, the drug was dissolved in acetone and then re-precipitated by adding a non-solvent (either water or an aqueous stabilizer solution), which yielded rod-like particles. In the second procedure, spheres, consisting of small elongated subunits, were obtained by acidification of basic aqueous solutions of the drug. The resulting particles were characterized in terms of their structure and surface charge characteristics. 相似文献
64.
Qinjun Kang Peter C. Lichtner Hari S. Viswanathan Amr I. Abdel-Fattah 《Transport in Porous Media》2010,82(1):197-213
We apply a multi-component reactive transport lattice Boltzmann model developed in previous studies for modeling the injection
of a CO2-saturated brine into various porous media structures at temperatures T = 25 and 80°C. In the various cases considered the porous medium consists initially of calcite with varying grain size and
shape. A chemical system consisting of Na+, Ca2+, Mg2+, H+, CO2°(aq){{\rm CO}_2^{\circ}{\rm (aq)}}, and Cl− is considered. Flow and transport by advection and diffusion of aqueous species, combined with homogeneous reactions occurring
in the bulk fluid, as well as the dissolution of calcite and precipitation of dolomite are simulated at the pore scale. The
effects of the structure of the porous media on reactive transport are investigated. The results are compared with a continuum-scale
model and the discrepancies between the pore- and continuum-scale models are discussed. This study sheds some light on the
fundamental physics occurring at the pore scale for reactive transport involved in geologic CO2 sequestration. 相似文献
65.
Claude Bardos Isabelle Catto Norbert Mauser Saber Trabelsi 《Archive for Rational Mechanics and Analysis》2010,198(1):273-330
In this paper, we formulate and analyze the multi-configuration time-dependent Hartree–Fock (MCTDHF) equations for molecular systems with pairwise interaction. This set of coupled nonlinear PDEs and ODEs is an approximation of the N-particle time-dependent Schrödinger equation based on (time-dependent) linear combinations of (time-dependent) Slater determinants. The “one-electron” wave-functions satisfy nonlinear Schrödinger-type equations coupled to a linear system of ordinary differential equations for the expansion coefficients. The invertibility of the one-body density matrix (full-rank hypothesis) plays a crucial rôle in the analysis. Under the full-rank assumption a fiber bundle structure emerges and produces unitary equivalence between different useful representations of the MCTDHF approximation. For a large class of interactions (including Coulomb potential), we establish existence and uniqueness of maximal solutions to the Cauchy problem in the energy space as long as the density matrix is not singular. A sufficient condition in terms of the energy of the initial data ensuring the global-in-time invertibility is provided (first result in this direction). Regularizing the density matrix violates energy conservation. However, global well-posedness for this system in L 2 is obtained with Strichartz estimates. Eventually, solutions to this regularized system are shown to converge to the original one on the time interval when the density matrix is invertible. 相似文献
66.
[(p‐Sulfonamidophenyl)azo]malononitrile ( 1a,b ) reacted with N‐cyclohexanemethylidene‐2‐cyanoacetohydrazide, N'‐arylmethylidene‐2‐cyanoacetohydrazide ( 3a‐c ), S‐methylthiourea and hydrazine hydrate to afford [1,2,4]triazolo‐[1,5‐a]pyridinone derivatives ( 2a,b ) & ( 4a‐c ), substituted pyrimidines 5a,b and 6a,b. The corresponding pyridazinones 7a,b were synthesized from the reaction of 1c,d with ethyl cyanoacetate. Compound 7a,b reacted with elemental sulfur to yield 8a,b . Compound 6a underwent cycloaddition with α‐cinnamonitrile 9a‐e to yield 11a‐c, 14 and 15 . Also, compound 6a reacted with β‐ketoester and 1,3‐diketones to give 16, 17 and 18 . 相似文献
67.
We report the synthesis and characterization of conjugated, conformationally rigid, and electroactive carbon-based nanotubes that we term tubularenes. These structures are constructed from a resorcin[nb]arene base. Cyclization of the conjugated aromatic nanotube is achieved in one-pot eight-fold C–C bond formation via Suzuki–Miyaura cross-coupling. DFT calculations indicate a buildup of strain energy in excess of 90 kcal mol−1. The resulting architectures contain large internal void spaces >260 Å3, are fluorescent, and able to accept up to 4 electrons. This represents the first scaffolding approach that provides conjugated nanotube architectures.First scaffolding approach to obtain tubular-shaped contorted aromatic architectures. 相似文献
68.
Sallam H. A. Abdel-Mageid R. E. Amr A. E. 《Russian Journal of General Chemistry》2019,89(11):2308-2313
Russian Journal of General Chemistry - In the current study, a series of macrocyclic tripeptide Schiff bases 2–6 were synthesized by using macrocyclic tripeptide hydrazide 1 as starting... 相似文献
69.
Raluca Anamaria Şeptelean Amr A. A. Attia Alexandru Lupan R. Bruce King 《International journal of quantum chemistry》2019,119(9):e25880
The lowest energy structures for all of the eight-vertex [M]CB6H7 {[M] = CpFe, CpRu. Co(CO)2, Rh(CO)2, (Me3P)2Fe(H), (Me3P)2Ru(H)}, [M]C2B5H7 {[M] = CpMn, CpRe, Cr(CO)3, Mo(CO)3}, and [M]2C2B4H6 ([M] = CpFe, CpRu) systems having 16 skeletal electrons were found by density functional theory to be capped pentagonal bipyramids providing a degree 6 vertex for a metal atom. Thus the capped pentagonal bipyramid plays a similar role for eight-vertex metallaboranes with 16 skeletal electrons as the isocloso deltahedra play in 9- and 10-vertex metallaboranes with 18 and 20 skeletal electrons, respectively. Furthermore, in all of these metallaborane systems the closo bisdisphenoidal structures were always found to be higher energy structures than their capped pentagonal bipyramidal isomers. For the bimetallic systems Cp2M2C2B4H6 (M = Fe, Ru) even higher energy hexagonal bipyramid structures with degree 6 vertices for both metal atoms were also found. 相似文献
70.
The paper describes some physical properties of poly(ether-amide)s (PEAs) prepared by solution polycondensation reaction of ether-amines such as 2,7-bis(4-aminophenoxy) naphthalene, 2,2-bis[4-(4-aminophenoxy)phenyl] propane, 1,4-bis(4-aminophenoxy methyl) cyclohexane and isophthalic acid. Resulting PEAs are high yield and have inherent viscosity ranging between 0.68–0.75 dL/g. The etheramines containing wholly, semi aromatic and aliphatic-aromatic segments were prepared by using two steps reaction. FTIR, 1H NMR, and elemental analyses were used for characterization of synthetic ether-amines and poly(ether-amide)s. PEAs films were prepared by solution casting technique then their thermal stability and mechanical properties were measured. TGA in nitrogen atmosphere shows that the PEAs are thermally stability, so 10% weight will be lost in the range of 335–358°C. Tensile strength and elongation at break of the PEA films ranged from 71.1–65.0 MPa and 6.48–8.41%, respectively. 相似文献