全文获取类型
收费全文 | 216篇 |
免费 | 12篇 |
国内免费 | 21篇 |
专业分类
化学 | 104篇 |
晶体学 | 1篇 |
力学 | 7篇 |
数学 | 51篇 |
物理学 | 86篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 11篇 |
2014年 | 5篇 |
2013年 | 11篇 |
2012年 | 17篇 |
2011年 | 19篇 |
2010年 | 10篇 |
2009年 | 9篇 |
2008年 | 21篇 |
2007年 | 16篇 |
2006年 | 8篇 |
2005年 | 8篇 |
2004年 | 13篇 |
2003年 | 18篇 |
2002年 | 17篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1982年 | 2篇 |
1976年 | 1篇 |
排序方式: 共有249条查询结果,搜索用时 15 毫秒
91.
Development of a neutron beam line and detector system for multiple prompt gamma-ray analysis 总被引:1,自引:1,他引:0
Y. Toh M. Oshima K. Furutaka A. Kimura M. Koizumi Y. Hatsukawa J. Goto 《Journal of Radioanalytical and Nuclear Chemistry》2008,278(3):703-706
A neutron beam line for multiple prompt gamma-ray analysis was constructed at the Japan Atomic Energy Agency. A detector system
for the MPGA was constructed at the C2-3-2 beam line in January 2005. It comprised eight (upgraded in March 2007) clover Ge
detectors with a BGO Compton suppressor. High efficiency detector system provides an advantage in terms of the detection limit
of MPGA when compared to the result of PGA. The supermirror neutron bender was improved and a supermirror neutron guide was
installed upstream of the sample position. 相似文献
92.
A short and efficient synthesis of enone 3, a key intermediate in the total synthesis of platencin (2), based on an intramolecular Diels-Alder reaction is described. 相似文献
93.
Pee Choon Toh 《The Ramanujan Journal》2016,40(2):359-365
Hirschhorn recently proved a pair of q-series identities that interlinked the coefficients of two infinite products. We use the theory of modular forms to extend his results from \(p=5\) to other primes and provide other examples of infinite products sharing similar properties. 相似文献
94.
Naohiko Arima Sunyoung Kim Masakazu Kojima Kim-Chuan Toh 《Computational Optimization and Applications》2017,66(3):453-479
The Lagrangian-doubly nonnegative (DNN) relaxation has recently been shown to provide effective lower bounds for a large class of nonconvex quadratic optimization problems (QAPs) using the bisection method combined with first-order methods by Kim et al. (Math Program 156:161–187, 2016). While the bisection method has demonstrated the computational efficiency, determining the validity of a computed lower bound for the QOP depends on a prescribed parameter \(\epsilon > 0\). To improve the performance of the bisection method for the Lagrangian-DNN relaxation, we propose a new technique that guarantees the validity of the computed lower bound at each iteration of the bisection method for any choice of \(\epsilon > 0\). It also accelerates the bisection method. Moreover, we present a method to retrieve a primal-dual pair of optimal solutions of the Lagrangian-DNN relaxation using the primal-dual interior-point method. As a result, the method provides a better lower bound and substantially increases the robustness as well as the effectiveness of the bisection method. Computational results on binary QOPs, multiple knapsack problems, maximal stable set problems, and quadratic assignment problems illustrate the robustness of the proposed method. In particular, a tight bound for QAPs with size \(n=50\) could be obtained. 相似文献
95.
Yoke Teng Toh Chang Phang Jian Rong Loh 《Mathematical Methods in the Applied Sciences》2019,42(1):175-185
In this paper, we develop a new, simple, and accurate scheme to obtain approximate solution for nonlinear differential equation in the sense of Caputo‐Fabrizio operator. To derive this new predictor‐corrector scheme, which suits on Caputo‐Fabrizio operator, firstly, we obtain the corresponding initial value problem for the differential equation in the Caputo‐Fabrizio sense. Hence, by fractional Euler method and fractional trapeziodal rule, we obtain the predictor formula as well as corrector formula. Error analysis for this new method is derived. To test the validity and simplicity of this method, some illustrative examples for nonlinear differential equations are solved. 相似文献
96.
Paper like free-standing hybrid single-walled carbon nanotubes air electrodes for zinc–air batteries
Nutan Gupta Tingji Toh Mak Wai Fatt Subodh Mhaisalkar Madhavi Srinivasan 《Journal of Solid State Electrochemistry》2012,16(4):1585-1593
Flexible electrode architectures based on non-functionalized (P2) and functionalized (P3) single-walled carbon nanotubes (SWNTs)
were fabricated via a simple vacuum filtration process. A hybrid layer of various compositions of P2- and P3-SWNTs forms free-standing
membranes (~80 μm in thickness), and their electrochemical performance was evaluated as an air electrode AEP2/P3 in zinc–air batteries. Such bifunctionalized air electrodes showed uniform surface morphology with interconnected micron-sized
porous structure with high porosity (~70%). The N2 adsorption isotherms at 77 K are of type IV with BET-specific surface areas of AE(60/40) and AE(80/20) to be 130.54 and 158.76 m2 g−1, respectively, thus facilitates high active surface area for active oxygen reduction/evolution reactions. BJH pore size distribution
of AE(60/40) and AE(80/20) shows maximum pores with diameter <15 nm. The zigzag interlaying of the SWNTs imparts mechanical stability and flexibility
in zinc–air batteries. Zinc–air batteries with optimized compositions of P2- and P3-SWNTs in air electrode AE(60/40) had ionic conductivity ~1 × 10−2 S cm−1 and delivered higher discharge capacity ~300 mAh g−1 as compared to AE(80/20) composition. The unique properties of AE(P2/P3) studied in this work would enable flexible air electrode architectures in future metal–air batteries. 相似文献
97.
98.
Z. Liu Y.H. Zhang X.H. Zhou M.L. Liu W.J. Luo Q.Y. Pan Z.G. Gan T. Hayakawa M. Oshima Y. Toh T. Shizima Y. Hatsukawa A. Osa T. Ishii M. Sugawara 《The European Physical Journal A - Hadrons and Nuclei》2002,13(3):277-280
Excited states of 142Ce, populated in deep inelastic reactions of 82Se projectiles bombarding 139La target, have been studied up to medium spins using in-beam γ spectroscopy techniques. Three new levels have been identified
at 2625, 2995, 3834 keV, and assigned as 8+, 9(-) and 11(-), respectively. These new yrast states follow closely the level systematics of the even mass N = 84 isotones. Their strctures have been discussed with the help of empirical shell model calculations.
Received: 2 November 2001 / Accepted: 15 January 2002 相似文献
99.
A time delay and integration imaging technique is presented and applied to internal surface contour measurement. Using the proposed optical arrangement, inspection of profiles of objects which are mounted on the internal surface of a hollow cylinder can be carried out. Tests conducted on objects with diameters ranging from 40 to 214 mm show good agreement with results obtained from conventional profilometer. 相似文献
100.