全文获取类型
收费全文 | 150篇 |
免费 | 4篇 |
专业分类
化学 | 119篇 |
力学 | 5篇 |
数学 | 12篇 |
物理学 | 18篇 |
出版年
2023年 | 1篇 |
2022年 | 17篇 |
2021年 | 12篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2014年 | 4篇 |
2013年 | 10篇 |
2012年 | 9篇 |
2011年 | 9篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 6篇 |
2007年 | 10篇 |
2006年 | 10篇 |
2005年 | 8篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1986年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有154条查询结果,搜索用时 281 毫秒
41.
A dynamic model for optimal design quality and return policies 总被引:1,自引:0,他引:1
Samar K. Mukhopadhyay Robert Setaputra 《European Journal of Operational Research》2007,180(3):1144-1154
A clearly explained and generous return policy has been established as a competitive weapon to enhance sales. From the firm’s point of view, a generous return policy will increase sales revenue, but will also increase cost due to increased likelihood of return. Design quality of the product has been used as a competitive weapon for a long time. This paper recognizes the relationship between design quality and price of the product, and the firm’s return policy. Quality level in the product would influence the amount of return directly. When the product quality is higher, the customer satisfaction rate will increase and the probability of return will decrease. We develop a profit-maximization model to jointly obtain optimal policies for the product quality level, price and the return policy over time. The model presented in this paper is dynamic in nature and considers the decisions as the product moves through the life cycle. We obtain a number of managerial guidelines for using marketing and operational strategy variables to obtain the maximum benefit from the market. We mention several future research possibilities. 相似文献
42.
43.
In [5] Ahlswede and Wolfowitz have obtained the capacities of a.v.ch. with binary output in a number of cases, essentially with the aid of a lemma which relates the capacity of the a.v.ch. to that of a suitable (“underlying”) d.m.c. A generalization of this lemma to a special kind of a.v.ch. with output alphabet b>2, has been given by Ahlswede (Lemma 1 of [1]) and used in [1] and [2] to prove the existence of the weak capacities of various channels under different conditions. We give a detailed proof of a weakened version of Ahlswede's lemma and show, in passing, that his lemma is incorrect. We then define certain special types of a.v.ch and, on the basis of the detailed analysis given by us earlier, we prove lemmas of a similar type for these a.v.ch. We are thus able to extend certain results given for binary output a.v.ch. in [4] and [5] to these special a.v.ch. for which b>2. 相似文献
44.
Synthesis and structural characterization of a polyoxometalate compound Na3(H2O)6 [Al(OH)6Mo6O18]-2H2O (1) have been described. Compound1 exhibits three-dimensional network structure in the solid state, which is assembled by Anderson-type heteropolyanions, [Al(OH)6Mo6O18]n
3n-
, as building blocks sharing sodium cations.1 possesses “sinuous” channels occupied by supramolecular water dimers as guests. Anderson anions, sodium-coordinated water
and crystal water are additionally involved in an intricate hydrogen-bonding network in the crystal of1. 相似文献
45.
Samaržija-Jovanović Suzana Jovanović Vojislav Jovanović Tijana Petković Branka Marković Gordana Porobić Slavica Marinović-Cincović Milena 《Journal of Thermal Analysis and Calorimetry》2022,147(22):12467-12479
Journal of Thermal Analysis and Calorimetry - This work investigated the thermal characteristics of irradiated composite materials formulated on the urea–formaldehyde resin (UF) and... 相似文献
46.
Mahmoud Sawsan A. Mohamed Fatma E. El-Sadek B. M. Elsawy M. M. Bendary Samar H. 《Journal of Solid State Electrochemistry》2021,25(8):2345-2360
Journal of Solid State Electrochemistry - In this context, the electrical conductivity and surface activity of cobalt sulphide (CoS) as counter electrode CE is improved by incorporating with... 相似文献
47.
Samar O. Aljazzar 《光谱学与光谱分析》2021,41(6):1971-1975
One of the phenolic acids is 4-hydroxybenzoic acid (HBA) which takes the form of a white crystalline solid with a molecular formula of C7H6O3, a melting point of 214.5 ℃ and a molecular weight of 138.12 g·mol-1. It soluble in polar organic solvents like acetone and alcohols, and slightly soluble in chloroform and water. The reactions between the metal ions and the HBA were carried out under specific conditions like (molar reaction was 2∶2 (ligand to metal), reaction temperature was 60 ℃, media was neutral (pH 7), and solvent was H2O ∶MeOH (1∶1). Under these conditions, the HBA was deprotonated to form (HOC6H4CO-2; L-). The ligand L- was coordinated to the metal ions forming the metal complexation. The reaction of 4-hydroxybenzoic acid (HOC6H4CO2H; HL) with the Ni(Ⅱ), Mn(Ⅱ) and Cu(Ⅱ) ions afford metal-complexes with gross formula of [Ni2L2(NO3)2(H2O)4], [Mn2L2(NO3)2(H2O)4] and [Cu2L2(NO3)2(H2O)4], respectively. These complexes were characterized by elemental analysis (CHN), magnetic susceptibility, UV-Vis spectra, infrared (IR), and X-ray powder diffraction (XRD) techniques. The complexes of HBA are insoluble in common solvents and hence molar conductance could not be measured, but this very insolubility indicates that the complexes are neutral. Data has demonstrated that the ligand (L-) was coordinated to the metal ion by bidentate bridging carboxylate group (COO-), with an octahedral geometry. Thus, HBA is expected to act as bidentate uninegative ions and the coordination number of the metal ions is six. XRD results showed that the complexes possess uniform and organized microstructures in the nanometer range with a main diameter in the range of 11~28 nm. 相似文献
48.
The compound (NH4)7[ VvO4W
10
VI
V
2
VI
O36]·ca.22H2O (1) has been synthesized from an aqueous ammonium acetate buffer (pH 4) containing sodium vanadate, sodium rungstate_and
sodium dithionite. Compound (1) crystallizes in a cubic space groupFm — 3, witha = 22.2001(6) ? and Z = 8. The anion [VvO4W
10
VI
V
2
IV
O36]7- is a typical Keggin type structure with VVO4 as the central tetrahedron. (1) has further been characterized by elemental analyses, redox titration, IR, EPR, and electronic
spectroscopy and room temperature magnetic moment measurement. 相似文献
49.
Guo Li Xu Guan Samar K Mukhopadhyay 《The Journal of the Operational Research Society》2016,67(2):248-258
The last few decades have witnessed a huge growth of outsourcing in industry where the downstream firm assigns its production tasks to different upstream suppliers. This makes the supply chain structure more complicated and gives rise to some relevant operational questions. This paper focuses on a supply chain structure that consists of one assembler and two suppliers, and both suppliers’ production yields are stochastic. The assembler delegates the quantity decisions to the suppliers, and the two suppliers choose their production quantities either simultaneously or sequentially. We compare the suppliers’ equilibrium production strategies under these two scenarios. Our results show that the decision sequence can exert significant influences on the firm’s and channel’s equilibrium payoffs. At any given wholesale price, both suppliers produce more components under sequential moves than under simultaneous moves, and this results in higher payoffs for the suppliers, the assembler and the entire supply chain. The supplier’s profit increases if he can make the decision later under sequential moves. From the channel’s perspective, it is more beneficial for the supplier with a higher production cost to make the decision first. The assembler is able to extract more surplus by endogenously setting the wholesale price. However, this may make the suppliers worse off under sequential moves than under simultaneous moves. 相似文献
50.
We propose an adaptive finite element method for the solution of a coefficient inverse problem of simultaneous reconstruction of the dielectric permittivity and magnetic permeability functions in the Maxwell’s system using limited boundary observations of the electric field in 3D. 相似文献