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901.
Ahmed SA Odde S Daga PR Bowling JJ Mesbah MK Youssef DT Khalifa SI Doerksen RJ Hamann MT 《Organic letters》2007,9(23):4773-4776
A new latrunculin, oxalatrunculin B (3), was isolated from Red Sea sponge Negombata corticata. Extensive spectroscopic analysis revealed an unprecedented heterocycle in which the rare thiazolidinone ring found in latrunculins was oxidized with three additional oxygens. An actin polymerization inhibition assay agreed with MM-PBSA free energy calculations that 3 binds more weakly than latrunculin B to actin. Significant antifungal and anticancer activity of 3 was found, suggesting an alternate target in addition to actin for latrunculin bioactivity. 相似文献
902.
Pathak P Prasad GL Meziani MJ Joudeh AA Sun YP 《Langmuir : the ACS journal of surfaces and colloids》2007,23(5):2674-2679
The rapid expansion of a supercritical solution into a liquid solvent (RESOLV) technique with benign supercritical carbon dioxide was applied to obtain aqueous suspended nanoparticles of the highly potent anticancer drug paclitaxel. The paclitaxel nanoparticles were protected from agglomeration by using a known nontoxic stabilization agent. The aqueous suspended paclitaxel nanoparticles of different average particle sizes were evaluated in vitro against human breast cancer cells. The results suggest that the nanosized paclitaxel particles are effective, with an antineoplastic activity comparable to that of the commercial paclitaxel formulation. The technique should be generally applicable to the processing of nanoparticles from other important drugs with aqueous solubility problems. 相似文献
903.
Ritika Singh Pramod K. Singh Shri Prakash Pandey Sunanda Kakroo Pankaj K. Tripathi Rohit Kumar Yashika Bajaj 《Macromolecular Symposia》2024,413(1):2300095
A high-conducting salt-doped polymer electrolyte layer has been created here for use in photocell technologies. The solution casting method is used to produce ion conducting film where poly (methyl methacrylate) (PMMA) is used as the host polymer and potassium iodide (KI) as the dopant. The conductivity and amorphic increases of the polymer electrolytes with the addition of salt concentrations helps in the enhancement of the charge transfer properties. Using electrochemical impedance spectroscopy (EIS), ionic conductivity is evaluated where maximum conductivity is 3.99 × 10−6 S cm-1 at 20 wt% KI concentration. Polarized optical microscopy (POM) shows the reduction in crystallinity by salt doping, while Fourier transforms infrared spectroscopy (FTIR) shows the complexation as well as composite nature of the film. Ionic transference number (tion) measurement shows the predominantly ionic nature of this polymer electrolyte. 相似文献
904.
A. Misra 《Fortschritte der Physik》2004,52(1):5-27
We study the gauged sigma model and its mirror Landau‐Ginsburg model corresponding to type IIA on the Fermat degree‐24 hypersurface in WCP 4[1,1,2,8,12] (whose blow‐up gives the smooth CY3(3,243)) away from the orbifold singularities, and its orientifold by a freely‐acting antiholomorphic involution. We derive the Picard‐Fuchs equation obeyed by the period integral as defined in [1, 2], of the parent 𝒩 = 2 type IIA theory of [3]. We obtain the Meijer's basis of solutions to the equation in the large and small complex structure limits (on the mirror Landau‐Ginsburg side) of the abovementioned Calabi‐Yau, and make some remarks about the monodromy properties associated based on [4], at the same and another MATHEMATICAlly interesting point. Based on a recently shown 𝒩 = 1 four‐dimensional triality [6] between Heterotic on the self‐mirror Calabi‐Yau CY3(11,11), M theory on and F‐theory on an elliptically fibered CY4 with the base given by CP 1 × Enriques surface, we first give a heuristic argument that there can be no superpotential generated in the orientifold of of CY3(3,243), and then explicitly verify the same using mirror symmetry formulation of [2] for the abovementioned hypersurface away from its orbifold singularities. We then discuss briefly the sigma model and the mirror Landau‐Ginsburg model corresponding to the resolved Calabi‐Yau as well. 相似文献
905.
906.
A series of triphenylarsenic(V) derivatives Ph3As(OPri)[SC6H4N:C(R)CH2C(O)R′] have been synthesized by the reactions of triphenylarsenic(V)‐ isoproproxide, Ph3As(OPri)2 with the corresponding 2,2‐disubstituted benzothiazolines of the type (where R = CH3, R′ = CH3( 1 ); R = CH3, R′ = C6H5( 2 ); R = CH3, R′ = 4‐CH3C6H4( 3 ); R = CH3, R′ = 4‐ClC6H4( 4 ); and R = CF3, R′ = C6H5( 5 )) in equimolar ratio in refluxing benzene solution. Molecular weight measurements of these complexes show their monomeric nature in solution. Characterization of these compounds using elemental analyses, molecular weight measurements, and spectral studies (IR as well as NMR (1H and 13C)) shows the monofunctional bidentate nature of the ligands and a hexacoordination around the central arsenic atom in these organoarsenic(V) derivatives. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:76–80, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20233 相似文献
907.
We give explicit constructions of quantum symplectic affine algebras at level one using vertex operators. 相似文献
908.
Sandip Das Kulbir Soumyadip Ray Tarali Devi Somnath Ghosh Sarvesh S. Harmalkar Sunder N. Dhuri Padmabati Mondal Pankaj Kumar 《Chemical science》2022,13(6):1706
Small molecule activation and their transfer reactions in biological or catalytic reactions are greatly influenced by the metal-centers and the ligand frameworks. Here, we report the metal-directed nitric oxide (NO) transfer chemistry in low-spin mononuclear {Co(NO)}8, [(12-TMC)CoIII(NO−)]2+ (1-CoNO, S = 0), and {Cr(NO)}5, ([(BPMEN)Cr(NO)(Cl)]+) (4-CrNO, S = 1/2) complexes. 1-CoNO transfers its bound NO moiety to a high-spin [(BPMEN)CrII(Cl2)] (2-Cr, S = 2) and generates 4-CrNOvia an associative pathway; however, we did not observe the reverse reaction, i.e., NO transfer from 4-CrNO to low-spin [(12-TMC)CoII]2+ (3-Co, S = 1/2). Spectral titration for NO transfer reaction between 1-CoNO and 2-Cr confirmed 1 : 1 reaction stoichiometry. The NO transfer rate was found to be independent of 2-Cr, suggesting the presence of an intermediate species, which was further supported experimentally and theoretically. The experimental and theoretical observations support the formation of μ-NO bridged intermediate species ({Cr–NO–Co}4+). Mechanistic investigations using 15N-labeled-15NO and tracking the 15N-atom established that the NO moiety in 4-CrNO is derived from 1-CoNO. Further, to investigate the factors deciding the NO transfer reactivity, we explored the NO transfer reaction between another high-spin CrII-complex, [(12-TMC)CrII(Cl)]+ (5-Cr, S = 2), and 1-CoNO, showing the generation of the low-spin [(12-TMC)Cr(NO)(Cl)]+ (6-CrNO, S = 1/2); however, again there was no opposite reaction, i.e., from Cr-center to Co-center. The above results advocate clearly that the NO transfer from Co-center generates thermally stable and low-spin and inert {Cr(NO)}5 complexes (4-CrNO & 6-CrNO) from high-spin and labile Cr-complexes (2-Cr & 5-Cr), suggesting a metal-directed NO transfer (cobalt to chromium, not chromium to cobalt). These results explicitly highlight that the NO transfer is strongly influenced by the labile/inert behavior of the metal-centers and/or thermal stability rather than the ligand architecture.Nitric oxide activation and parameters influencing intermolecular transfer of nitric oxide. 相似文献
909.
Pankaj S Joshi 《Pramana》2000,55(4):529-544
An outstanding problem in gravitation theory and relativistic astrophysics today is to understand the final outcome of an
endless gravitational collapse. Such a continual collapse would take place when stars more massive than few times the mass
of the sun collapse under their own gravity on exhausting their nuclear fuel. According to the general theory of relativity,
this results either in a black hole, or a naked singularity — which can communicate with far away observers in the universe.
While black holes are (almost) being detected and are increasingly used to model high energy astrophysical phenomena, naked
singularities have turned into a topic of active discussion, aimed at understanding their structure and implications. Recent
developments here are reviewed, indicating future directions. 相似文献
910.
We recently proposed a second-order accurate ψ-v formulation of the steady-state Navier-Stokes (N-S) equations on compact Cartesian nonuniform grids. In the current work, we extend the ideas of the aforesaid formulation and propose a second-order spatially compact, implicit, stable ψ-v formulation for the unsteady incompressible N-S equations. Contrary to the existing ψ-v finite difference formulations which use grid transformation, the proposed scheme is developed for nonuniform Cartesian grids without transformation specifically designed for two-dimensional laminar flow past bluff bodies. It has been implemented on problems of internal flows inside curved regions as well as those involving fluid-embedded body interaction. However, the robustness of the scheme is highlighted by the accurate resolution of a host of complex flows past bluff bodies with different physical set-ups and boundary conditions. It was seen to handle problems involving both uniform and accelerated flows across a wide range of structures of varied shape, namely, a flat plate, a circular cylinder, inclined square cylinder, and a wedge in channel hinged to the wall. Apart from elegantly capturing all the details of the shedded vortex structures under different circumstances, the scheme was also able to handle both Dirichlet and Neumann boundary with equal ease. In all the cases, our results are found to be extremely close to the available numerical and experimental results. 相似文献