全文获取类型
收费全文 | 433篇 |
免费 | 11篇 |
国内免费 | 1篇 |
专业分类
化学 | 204篇 |
晶体学 | 2篇 |
力学 | 7篇 |
数学 | 49篇 |
物理学 | 183篇 |
出版年
2024年 | 2篇 |
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 5篇 |
2019年 | 9篇 |
2018年 | 13篇 |
2017年 | 6篇 |
2016年 | 17篇 |
2015年 | 11篇 |
2014年 | 16篇 |
2013年 | 24篇 |
2012年 | 34篇 |
2011年 | 31篇 |
2010年 | 22篇 |
2009年 | 17篇 |
2008年 | 20篇 |
2007年 | 20篇 |
2006年 | 19篇 |
2005年 | 2篇 |
2004年 | 10篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 11篇 |
1995年 | 9篇 |
1994年 | 11篇 |
1993年 | 11篇 |
1992年 | 9篇 |
1991年 | 8篇 |
1990年 | 12篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1975年 | 2篇 |
1965年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有445条查询结果,搜索用时 15 毫秒
11.
12.
13.
14.
15.
Seetaram Mohapatra Chittaranjan Bhanja Satyaban Jena Subhendu Chakroborty Sabita Nayak 《合成通讯》2013,43(15):1993-2007
The Bestmann–Ohira reagent serves as a versatile platform for the regioselective construction of pyrazoles, triazoles, and oxazoles via a cycloaddition reaction and multicomponent reaction. In this review, we have summarized the most significant advances in the Bestmann–Ohira reagent (BOR)–assisted construction of functionalized five–membered heterocycles reported in the literature up to 2012. 相似文献
16.
Arijit Sengupta M. S. Murali P. K. Mohapatra 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(1):405-412
On the growing awareness of the environmental impact associated with the use of volatile organic diluents, room temperature ionic liquid gained world-wild acceptance as environmentally benign diluents for actinide partitioning. The observed unusual behavior of less extraction efficiency of Eu with TODGA in RTIL in comparison with that of Am-TODGA was addressed in this paper. The stoichiometry of Am-TODGA complex was found to be 1:2 while that of Eu-TODGA was 1:1. More the ligand molecules associated in the metal ligand complex, the organophilicity of the complex will be more and the solubility of the metal–ligand complex in RTIL will be more which reflects in the higher distribution ratio for Am. In RTIL both Am and Eu showed slower kinetics of extraction with TODGA which can be attributed to the high viscosity coefficient of RTIL compared to the molecular diluents. The observed slower kinetics of extraction was quantified and found to follow first order kinetics with the rate constant of 5.5 × 10?4 s?1. The formation constant of Am-TODGA complex was found to be more (4.18 × 108 M?1) than Eu-TODGA complex (3.31 × 108 M?1) in RTIL. The parameters viz. diffusion coefficient, activation energy for Eu(III)/Eu(II) were determined and found to be 3.08 × 10?8/cm2 s?1 (at 303 K) and 39.34 kJ mol?1 respectively. The thermodynamic parameters ΔG, ΔH and ΔS for the reaction were evaluated using the linear regression of the plot of E 0* versus T. The redox reaction was found to be exothermic with decrease in entropy value. 相似文献
17.
In an attempt to uncover any underlying structure in the neutrino mass matrix, we discuss the possibility that the ratios of elements of its Majorana mass matrix are equal. We call this “strong scaling Ansatz” for neutrino masses and study its phenomenological implications. Of three possible independent scale invariant possibilities, only one is allowed by current data, predicting in a novel way the vanishing of Ue3 and an inverted hierarchy with the lightest neutrino having zero mass. The Ansatz has the additional virtue that it is not affected by renormalization running. We also discuss explicit models in which the scaling Ansatz is realized. 相似文献
18.
Artuso M Blusk S Butt J Li J Menaa N Mountain R Nisar S Randrianarivony K Sia R Skwarnicki T Stone S Wang JC Zhang K Bonvicini G Cinabro D Dubrovin M Lincoln A Asner DM Edwards KW Naik P Briere RA Ferguson T Tatishvili G Vogel H Watkins ME Rosner JL Adam NE Alexander JP Cassel DG Duboscq JE Ehrlich R Fields L Galik RS Gibbons L Gray R Gray SW Hartill DL Heltsley BK Hertz D Jones CD Kandaswamy J Kreinick DL Kuznetsov VE Mahlke-Krüger H Mohapatra D Onyisi PU Patterson JR Peterson D Pivarski J 《Physical review letters》2007,99(19):191801
Using a 281 pb{-1} data sample collected at the psi(3770) with the CLEO-c detector, we present the first absolute branching fraction measurement of the decay D0-->K(-)pi(+)pi(-)e(+)nu(e) at a statistical significance of about 4.0 standard deviations. We find 10 candidates consistent with the decay D0-->K(-)pi(+)pi(-)e(+)nu(e). The probability that a background fluctuation accounts for this signal is less than 4.1 x 10{-5}. We find B(D0-->K(-)pi(+)pi(-)e(+)nu(e)) = [2.8{-1.1}{+1.4}(stat)+/-0.3(syst)]x10{-4}. By restricting the invariant mass of the hadronic system to be consistent with K1(1270), we obtain the product of branching fractions B(D{0}-->K{1}{-}(1270)e{+}nu{e})xB(K1-(1270)-->K{-}pi{+}pi{-})=[2.5{-1.0}{+1.3}(stat)+/-0.2(syst)]x10{-4}. Using B(K1-(1270)-->K{-}pi{+}pi{-})=(33+/-3)%, we obtain B(D{0}-->K{1}{-}(1270)e{+}nu{e})=[7.6{-3.0}{+4.1}(stat)+/-0.6(syst)+/-0.7]x10{-4}. The last error accounts for the uncertainties in the measured K1-(1270)-->K{-}pi{+}pi{-} branching fractions. 相似文献
19.
Meccanica - A particular hydro-elastic model is considered to examine a radiation problem involving an immersed sphere in an infinitely extended ice-covered sea, where the lower surface is... 相似文献
20.