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901.
902.
Terminal phosphino groups of [Re2(CO)9(η1-P-P)] (P-P = diphosphines) are activated towards oxidation by Me3NO. The respective reactions of Me3NO with [Re2(CO)9{η1-P(o-anisyl)2(CH2)3PPh2}], [Re2(CO)9{η1-PPh2(CH2)3P(o-anisyl)2}] and [Re2(CO)9(η1-trans-PPh2CHCHPPh2)] were studied to investigate the mechanism of this oxidation. The results are consistent with an intramolecular pathway involving a cyclic intermediate, without exchange of the coordinated and terminal phosphino groups. A mechanism which involves an interaction of the terminal phosphino group with a carbonyl ligand is proposed. In sharp contrast to eq-[Re2(CO)9(η1-P-P)] (P-P = Ph2P(CH2)nPPh2, n = 1-6), eq-[Re2(CO)9(η1-trans-PPh2CHCHPPh2)] appears to be indefinitely stable towards equatorial → axial isomerization at room temperature, thus, allowing its crystal structure to be determined. 相似文献
903.
A new complex of copper(II) picrate (pic) with 1, 3‐bis(1‐allaylbenzimidazol‐2‐yl)‐2‐oxopropane (aobb), with the composition [Cu(aobb)2](pic)2, was synthesized and characterized. The crystal structure of the copper(II) complex revealed that the coordination environment around the central copper(II) atom is a distorted octahedral arrangement. Electronic absorption spectroscopy, ethidium bromide displacement experiments and viscosity measurements indicate that the ligand and the CuII complex can strongly bind to calf thymus DNA, presumably by an intercalation mechanism. Furthermore, the antioxidant activity of the CuII complex was determined by superoxide and hydroxyl radical scavenging method in vitro, which indicate that the CuII complex has the activity to suppress OH · and O2 · –. 相似文献
904.
Two aggregation-induced emission (AIE) macrocycles (DMP[5]-TPE and PCP[5]-TPE) were prepared by embedding Tetraphenylethene (TPE) unit into the skeletons of Dimethoxypillar[5]arene (DMP[5]) and [15]Paracyclophane ([15]PCP) at meso position, respectively. In crystal, the PCP[5]-TPE showed a distorted cavity, and the incubation of hexane inside the DMP[5]-TPE cavity caused a distinct change in the molecular conformation compared to PCP[5]-TPE. There was no complexation between PCP[5]-TPE and 1,4-dicyanobutane (DCB). UV absorption experiments showed the distorted cavity of DMP[5]-TPE hindered association with DCB. 相似文献
905.
In this paper,we report a novel approach to the heteroaryl-condensed nuclei of natural furo[3,2-a]carbazole alkaloids.Our synthetic studies use N-phthaloyl tryptophan methyl ester as starting material and zinc ion mediated transamination reaction as the key step.This work also implicated a novel strategy to assemble other [a]-fused carbazoles. 相似文献
906.
C.K. Fan 《Journal of Algebraic Combinatorics》1996,5(3):175-189
Let (W, S) be a Coxeter group associated to a Coxeter graph which has no multiple bonds. Let H be the corresponding Hecke Algebra. We define a certain quotient \-H of H and show that it has a basis parametrized by a certain subset W
cof the Coxeter group W. Specifically, W
cconsists of those elements of W all of whose reduced expressions avoid substrings of the form sts where s and t are noncommuting generators in S. We determine which Coxeter groups have finite W
cand compute the cardinality of W
cwhen W is a Weyl group. Finally, we give a combinatorial application (which is related to the number of reduced expressions for w W
cof an exponential formula of Lusztig which utilizes a specialization of a subalgebra of \-H. 相似文献
907.
YanFei Zhao MingHao Zhao Ernian Pan CuiYing Fan 《International Journal of Solids and Structures》2014
Based on the extended Stroh formalism, we first derive the extended Green’s functions for an extended dislocation and displacement discontinuity located at the interface of a piezoelectric bi-material. These include Green’s functions of the extended dislocation, displacement discontinuities within a finite interval and the concentrated displacement discontinuities, all on the interface. The Green’s functions are then applied to obtain the integro-differential equation governing the interfacial crack. To eliminate the oscillating singularities associated with the delta function in the Green’s functions, we represent the delta function in terms of the Gaussian distribution function. In so doing, the integro-differential equation is reduced to a standard integral equation for the interfacial crack problem in piezoelectric bi-material with the extended displacement discontinuities being the unknowns. A simple numerical approach is also proposed to solve the integral equation for the displacement discontinuities, along with the asymptotic expressions of the extended intensity factors and J-integral in terms of the discontinuities near the crack tip. In numerical examples, the effect of the Gaussian parameter on the numerical results is discussed, and the influence of different extended loadings on the interfacial crack behaviors is further investigated. 相似文献
908.
909.
Jing-cai Yao Xin-xiang Cao Li Zhang Yu-fang Wang Jin-bo Guo Cui-ping Fan 《Journal of chemical crystallography》2011,41(9):1400-1405
Abstract
The title complex {[Yb(1,4-BDC)1.5(H2O)4]·H2O}n (1) (1,4-BDC = 1,4-benzenedicarboxylate) has been hydrothermally synthesized and structurally characterized by the single crystal X-ray diffraction. Crystals of compound 1 belongs to the triclinic crystal system, space group P-1; a = 7.549(3) ?, b = 10.072(4) ?, c = 10.470(4) ?, α = 87.810(4)°, β = 82.531(4)°, γ = 86.306(4)°, V = 787.3(5) ?3, Z = 2. The Yb(III) atoms are linked by the deprotonated 1,4-BDC ligands in two kinds of bridging modes. Four Yb(III) atoms at each corner (nodes) and four 1,4-BDC ligands at each edge (spacers) form a edge–sharing 36-membered rings. The rhombohedral Yb4(1,4-BDC)4 arranged in an alternating fashion to construct a 1D ladder-like chain along the c axis. Two neighboring chains are linked to each other in a parallel fashion to construct 3D supramolecular structure by O–H···O hydrogen bonds and π–π stacking interactions. In addition, the properties of thermogravimetric analysis and magnetic behaviors of the complex have been also discussed. 相似文献910.
Organic electrode materials (OEMs) are being investigated as promising candidates for aqueous zinc-ion batteries (AZIBs) owing to their environmental friendliness, cost-effectiveness, and structural diversity, and tunability. Understanding the correlation between structural regulation of OEMs and their electrochemical property in AZIBs is vital to rational design of OEMs. Herein, we first discuss the fundamentals of the energy storage mechanism of OEMs. Then, strategies to improve the electrochemical performance, including the specific capacity, voltage, rate capability, and cycling stability, are elaborated from the perspective of molecular engineering. Finally, we share our views on the remaining challenges and prospects of OEMs in AZIBs. 相似文献