全文获取类型
收费全文 | 1981篇 |
免费 | 44篇 |
国内免费 | 4篇 |
专业分类
化学 | 1205篇 |
晶体学 | 16篇 |
力学 | 41篇 |
数学 | 185篇 |
物理学 | 582篇 |
出版年
2024年 | 6篇 |
2023年 | 16篇 |
2022年 | 47篇 |
2021年 | 33篇 |
2020年 | 40篇 |
2019年 | 52篇 |
2018年 | 43篇 |
2017年 | 52篇 |
2016年 | 75篇 |
2015年 | 41篇 |
2014年 | 80篇 |
2013年 | 143篇 |
2012年 | 114篇 |
2011年 | 120篇 |
2010年 | 89篇 |
2009年 | 87篇 |
2008年 | 116篇 |
2007年 | 105篇 |
2006年 | 71篇 |
2005年 | 56篇 |
2004年 | 48篇 |
2003年 | 36篇 |
2002年 | 37篇 |
2001年 | 33篇 |
2000年 | 27篇 |
1999年 | 13篇 |
1998年 | 9篇 |
1997年 | 11篇 |
1996年 | 17篇 |
1995年 | 22篇 |
1994年 | 22篇 |
1993年 | 33篇 |
1992年 | 26篇 |
1991年 | 25篇 |
1990年 | 23篇 |
1989年 | 24篇 |
1988年 | 12篇 |
1987年 | 28篇 |
1986年 | 19篇 |
1985年 | 21篇 |
1984年 | 15篇 |
1983年 | 17篇 |
1982年 | 14篇 |
1981年 | 15篇 |
1980年 | 15篇 |
1979年 | 20篇 |
1978年 | 6篇 |
1974年 | 5篇 |
1973年 | 6篇 |
1965年 | 7篇 |
排序方式: 共有2029条查询结果,搜索用时 15 毫秒
141.
142.
Ram C. Maurya Deen D. Mishra Surendra K. Jaiswal Sudipta Mukherjee 《Transition Metal Chemistry》1992,17(5):381-383
Some new low-spin hexacoordinated cyanonitrosyl complexes of Cr1 of the type [Cr(NO)(CN)2(L)2(H2)], where L is an aromatic aldehyde oxime or Mannich base, have been prepared by the interaction or K3[Cr(NO)(CN)5]· H2O with L in aqueous AcOH, and characterized by a range of physico-chemical techniques, I.r. data suggest that all the oxime
derivatives and Mannich bases act as monodentate ligands by coordinating through the aromatic nitrogen.
TMC 2564 相似文献
143.
Shalini Bagchi Kasturi Roychowdhury A.P. Mishra A. Roy Chowdhury 《Communications in Nonlinear Science & Numerical Simulation》2010,15(2):275-280
Excitation of nonlinear waves in a quantum dusty plasma with various effects is analyzed when the geometry is cylindrical.This introduces the effect of finite boundary conditions on the solitary waves so generated. it is observed that the nonlinear equation deduced is cylindrical KP–Burger type leading to the generation of Shock Wave. Different situations which arises in various parameter regions are considered separately and the form of the nonlinear excitations are obtained explicitly. 相似文献
144.
Traditional inventory models assume that a buyer places one order with a supplier in each order cycle. A large number of researchers have studied the benefits of dual sourcing such that an order quantity is split and placed simultaneously with two suppliers. We show that many of the benefits of dual sourcing are due to order splitting rather than using two suppliers. We investigate order splitting with one supplier such that the first part of the order is sent out immediately but the second part of the order is released later (scheduled-release). Through extensive computational results, we show that in many situations where dual sourcing or the use of a cheaper supplier would be cost effective, single sourcing with order splitting using scheduled-release orders is better. The paper provides a quantitative rationale to continue with one supplier. We also summarize the qualitative reasons to prefer single sourcing or multiple sourcing. 相似文献
145.
146.
Numerical Algorithms - Inthis paper, we discuss two first-order completely discrete schemes based on Backward Euler and its linearized variant methods for the 2D Sobolev equations with... 相似文献
147.
Surface tension measurements can be used to investigate molecular complex formation in liquid solutions for strong and weak
complexes. The association constant and epthalpy for triethylamine-iodine, hexamethylbenzene-tetracyanoethylene and ethanol-iodine
in cyclohexane are 4·55×103, 218 and 0.93M−1 at 25° C and 12·5, 7·7 and 5·1 kcal/mol respectively. These values compare well with those reported in the literature by
other methods. 相似文献
148.
We consider a setting where there is a manufacturer who wants to procure multiple items from a set of suppliers each of whom can supply one or more of these items (bundles). We design an ascending price auction for such a setting which implements the Vickrey–Clarke–Groves outcome and truthful bidding is an ex post Nash equilibrium. Our auction maintains non-linear and non-anonymous prices throughout the auction. This auction has a simple price adjustment step and is easy to implement in practice. As offshoots of this auction, we also suggest other simple auctions (in which truthful bidding is not an equilibrium by suppliers) which may be suitable where incentives to suppliers are not a big concern. Computer simulations of our auction show that it is scalable for the multi-unit case, and has better information revelation properties than its descending auction counterpart. 相似文献
149.
Fozia Z. Haque Mohammad Ramzan Parra Hafsa Siddiqui Neha Singh Nitu Singh Padmini Pandey K. M. Mishra 《Optics and Spectroscopy》2016,120(3):408-414
Self-assembled one-dimensional (1D) zinc oxide (ZnO) rods and three-dimensional (3D) cupric oxide (CuO) cubes like nanostructures with a mean crystallite size of approximately 33 and 32 nm were synthesized through chemical route in the presence of polyvinylpyrrolidone (PVP) under mild synthesis conditions. The technique used for the synthesis of nanoparticles seems to be an efficient, inexpensive and easy method. X-Ray diffraction patterns confirmed well crystallinity and phase purity of the as prepared samples, followed by the compositional investigation using Fourier Transform Infrared (FT-IR) spectroscopy. The formation of ZnO nanorods and CuO nanocubes like structures were through Scanning Electron Microscopy (SEM) images. The mechanism and the formation factors of the self-assembly were discussed in detail. It was clearly observed from results that the concentration of precursors and PVP were important factors in the synthesis of self-assembly ZnO and CuO nanostructures. These self-assembly nanostructures maybe used as novel materials in various potential applications. 相似文献
150.
We have used Ramakrishnan–Yussouff (RY) density functional theory (DFT) to explore the topology of the phase diagram of two-component charge stabilised colloidal suspensions confined to a two-dimensional plane. The particles of the system interact via purely repulsive soft core Yukawa potential. Pair correlation functions (PCFs) used as input informations in DFT were calculated by solving both the hypernetted chain (HNC) and Percus–Yevick (PY) integral equation theories. To test the relative performance of the HNC and PY theories in the context of phase transitions, we have also studied the corresponding one-component systems. We found that RY DFT with HNC PCFs does not stabilise solid in both the one- and two-component cases, whereas the PY theory does. By considering the freezing into the substitutionally disordered triangular solid, we found that the temperature-composition phase diagrams of the binary mixture are narrow spindles whose thickness depends on the symmetry of the mixture components and the value of the screening constant of the Yukawa potential. Although the phase diagram obtained by RY DFT with structural inputs calculated by the PY theory is found to be shifted to higher temperature region in the temperature-composition plane, however, it captures qualitatively all the essential features of the phase diagram. Our results are in principle verifiable through computer simulations and experiments. 相似文献