全文获取类型
收费全文 | 102186篇 |
免费 | 5696篇 |
国内免费 | 13051篇 |
专业分类
化学 | 79893篇 |
晶体学 | 1288篇 |
力学 | 2446篇 |
综合类 | 996篇 |
数学 | 14907篇 |
物理学 | 21403篇 |
出版年
2024年 | 95篇 |
2023年 | 826篇 |
2022年 | 1749篇 |
2021年 | 1973篇 |
2020年 | 2456篇 |
2019年 | 2467篇 |
2018年 | 2092篇 |
2017年 | 2982篇 |
2016年 | 3136篇 |
2015年 | 2731篇 |
2014年 | 3822篇 |
2013年 | 7667篇 |
2012年 | 6886篇 |
2011年 | 5611篇 |
2010年 | 4809篇 |
2009年 | 6425篇 |
2008年 | 6668篇 |
2007年 | 6940篇 |
2006年 | 6202篇 |
2005年 | 5279篇 |
2004年 | 4944篇 |
2003年 | 4053篇 |
2002年 | 5293篇 |
2001年 | 3078篇 |
2000年 | 3442篇 |
1999年 | 3041篇 |
1998年 | 2749篇 |
1997年 | 1831篇 |
1996年 | 1558篇 |
1995年 | 1447篇 |
1994年 | 1318篇 |
1993年 | 1109篇 |
1992年 | 1043篇 |
1991年 | 715篇 |
1990年 | 580篇 |
1989年 | 569篇 |
1988年 | 409篇 |
1987年 | 328篇 |
1986年 | 293篇 |
1985年 | 269篇 |
1984年 | 264篇 |
1983年 | 168篇 |
1982年 | 233篇 |
1981年 | 213篇 |
1980年 | 220篇 |
1979年 | 197篇 |
1978年 | 185篇 |
1977年 | 139篇 |
1976年 | 120篇 |
1973年 | 83篇 |
排序方式: 共有10000条查询结果,搜索用时 625 毫秒
91.
GAO Jing ZHOU Xiaohua CHEN Xun Chongqing University Chemical Engineering Department Chongqing China 《Chinese Journal of Reactive Polymers》2006,(2)
1. INTRODUCTION In the process of coking plant, about 30%~35% sulfur is transformed to H2S and some other sulfide, which form impurity in coal gas together with NH3 and HCN. Only 0.1% H2S containing in air can lead to die, so it is very important to carry on desulphurization and decyanation with coal gas [1~3]. Currently desulphurization and decyanation craft technique have Dry Oxidation Technology, Wet Oxidation Technology and Liquid Absorption Technology [2] three main kinds. The… 相似文献
92.
Electron spin resonance spectra of Mn2+ in diluted solid solutions of MnO2 in Y2O3 have been studied at room temperature for Mn concentrations between 0.20 and 2.00 mol%. Isolated Mn2+ ions in sites with two different symmetries were observed, as well as Mn2+ ions coupled by the exchange interaction. The relative concentration of isolated to coupled Mn2+ ions decreases with increasing manganese concentration. The results are consistent with the assumption that the manganese ions occupy preferentially the C2 symmetry sites. A theoretical calculation based on this model yields an effective range of the exchange interaction between Mn2+ ions of 0.53 nm, of the same order as that of Mn2+ ions in CaO. 相似文献
93.
许多实验对用CsI(Tl)闪烁晶体作为探测器来寻找和探测暗物质的可行性进行了研究.本工作利用8MeV单能中子轰击CsI(Tl)晶体探测器来研究Cs核和I核的QuenchingFactor.在数据处理中,运用脉冲形状甄别(PSD)方法来分辨反冲核信号和本底信号.实验结果表明,在7keV到132keV的能区中,Quench ingFactor随着反冲核能量的减少而增加.在探测暗物质的实验中,这一性质对于CsI(Tl)晶体探测器获得较低的能量阈值是很有利的. 相似文献
94.
B. Dubrulle F. Hersant 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(3):379-386
We generalize an analogy between rotating and stratified shear flows. This analogy is summarized in Table 1. We use this analogy
in the unstable case (centrifugally unstable flow vs. convection) to compute the torque in Taylor-Couette configuration, as a function of the Reynolds number. At low Reynolds
numbers, when most of the dissipation comes from the mean flow, we predict that the non-dimensional torque G = T/ν2
L, where L is the cylinder length, scales with Reynolds number R and gap width η, G = 1.46η3/2(1 - η)-7/4
R
3/2. At larger Reynolds number, velocity fluctuations become non-negligible in the dissipation. In these regimes, there is no
exact power law dependence the torque versus Reynolds. Instead, we obtain logarithmic corrections to the classical ultra-hard (exponent 2) regimes: G = 0.50
. These predictions are found to be in excellent agreement with avail-able experimental data. Predictions for scaling of velocity
fluctuations are also provided.
Received 7 June 2001 and Received in final form 7 December 2001 相似文献
95.
S.-Y. Sheu D.-Y. Yang H.L. Selzle E.W. Schlag 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):557-563
Charge transport is one important example of signal transduction in a protein which is responsible for action at a distance,
and is a fundamental process in biochemical action. A model is presented in which electronic effects interact with motional
processes to combine into a bifunctional model. This model is investigated with new detailed molecular dynamics calculations
and successfully explains such action at a distance.
Received 1st February 2002 / Received in final form 26 May 2002 Published online 13 September 2002 相似文献
96.
阐述检测物体是否产生了电场的方法;通过实际检测证实立方体永磁体既产生了负静电场,也产生了正静电场,并测定了具体的场强. 相似文献
97.
meso-Tetra(n-hexyloxycarbonyl)porphyrin was found to be converted into porphine, the mother compound of porphyrins, in a 77% yield when heated in aqueous sulfuric acid at 180 °C over 30 min under an inert atmosphere. The observation demonstrates that the substituted porphyrin serves as a novel and useful precursor for porphine. 相似文献
98.
We obtain upper bounds for the tail distribution of the first nonnegative sum of a random walk and for the moments of the overshoot over an arbitrary nonnegative level if the expectation of jumps is positive and close to zero. In addition, we find an estimate for the expectation of the first ladder epoch. 相似文献
99.
100.
Kasper K. Berthelsen Jesper Møller 《Bulletin of the Brazilian Mathematical Society》2002,33(3):351-367
This primer provides a self-contained exposition of the case where spatial birth-and-death processes are used for perfect
simulation of locally stable point processes. Particularly, a simple dominating coupling from the past (CFTP) algorithm and
the CFTP algorithms introduced in [13], [14], and [5] are studied. Some empirical results for the algorithms are discussed.
Received: 30 June 2002 相似文献