全文获取类型
收费全文 | 291篇 |
免费 | 27篇 |
国内免费 | 31篇 |
专业分类
化学 | 209篇 |
晶体学 | 1篇 |
力学 | 15篇 |
数学 | 50篇 |
物理学 | 74篇 |
出版年
2023年 | 1篇 |
2022年 | 7篇 |
2021年 | 8篇 |
2020年 | 10篇 |
2019年 | 8篇 |
2018年 | 10篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2015年 | 7篇 |
2014年 | 11篇 |
2013年 | 22篇 |
2012年 | 19篇 |
2011年 | 30篇 |
2010年 | 11篇 |
2009年 | 17篇 |
2008年 | 22篇 |
2007年 | 22篇 |
2006年 | 14篇 |
2005年 | 12篇 |
2004年 | 20篇 |
2003年 | 16篇 |
2002年 | 17篇 |
2001年 | 12篇 |
2000年 | 8篇 |
1999年 | 8篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1979年 | 2篇 |
排序方式: 共有349条查询结果,搜索用时 15 毫秒
321.
M. Štubňa J. Ričány Š. Rohár F. Šebesta J. Sedláček A. Zeman 《Journal of Radioanalytical and Nuclear Chemistry》1979,51(1):161-166
The method of monitoring of U, Pu and some fission products (103,106Ru,134,137Cs and141,144Ce) in gaseous CO2 coolant is described. The method is based on the retention of the radionuclides studied by membrane filters built in by-pass
of the burst-cartridge detection (BCD) system. The purpose of the present study was the determination of U, Pu in CO2 and the verification of the possibility of the indirect monitoring of U and Pu contents in the coolant, using the gamma-spectrometric
determination of selected fission products retained by the filter. For calibration of the proposed method after decomposition
of the filters, uranium was determined spectrophotometrically using Arsenazo III, plutonium was determined radiometrically
after its separation by extraction with 2-thenoyltrifluoracetone and the fission products were determined by gamma-spectrometry.
From the results obtained it follows that a correlation exists between the U and Pu content in the coolant and the activity
of certain fission products retained on the filter. 相似文献
322.
Polymer‐supported α‐selenoaldehydes easily obtained by reaction of polymer‐supported 4‐(phenylseleno)morpholine with aldehydes react with Grignard reagents to form polymer‐supported β‐hydroxyalkyl selenides, which were treated with thionyl chloride/triethylamine leading to (E)‐1,2‐disubstituted ethenes in good yields. 相似文献
323.
324.
325.
Youri Davydov Ričardas Zitikis 《Annals of the Institute of Statistical Mathematics》2008,60(2):345-365
We suggest simple and easily verifiable, yet general, conditions under which multi-parameter stochastic processes converge
weakly to a continuous stochastic process. Connections to, and extensions of, R. Dudley’s results play an important role in
our considerations, and we therefore discuss them in detail. As an illustration of general results, we consider multi-parameter
stochastic processes that can be decomposed into differences of two coordinate-wise non-decreasing processes, in which case
the aforementioned conditions become even simpler. To illustrate how the herein developed general approach can be used in
specific situations, we present a detailed analysis of a two-parameter sequential empirical process. 相似文献
326.
Guang‐Ri Xu Y. P. Zhang Jian Zhong Tao Sunghyun Kim Zun‐Ung Bae 《Electroanalysis》2007,19(10):1085-1092
In this paper, we describe the double modification of the glassy carbon electrode surface with two polymer layers for the selective determination of dopamine. The first layer was the electropolymerized macrocyclic nickel complex acting as an electrocatalyst for the dopamine oxidation and the second layer the polyurethane benzyl L ‐glutamate (PUBLG) for screening interfering species. Hydrolyzed PUBLG (PU‐C) showed a better screening effect. Thus prepared GC/Ni(II) complex film/PU‐C electrodes exhibited improved selectivity and better performance than unmodified counterparts, with minimum passivation even in the presence of large excess of interferents. Under optimal conditions, these electrodes showed a linear response over a dopamine concentration range of 2.5×10?7 and 3.0×10?5 M with a correlation coefficient of 0.999 and detection limit (at S/N=3) of 8.0×10?8 M. The recoveries of dopamine in the 5‐fold diluted human urine sample were 96.9% for 4 measurements. The rate constant for the dopamine oxidation measured by the rotating disk electrode was found to be 1.1×10?3 cm s?1. 相似文献
327.
The addition of a constant ‘competing risk’ corresponding to an additional, usually less significant, source of failure, frequently improves the fit in reliability and survival analysis. This is often termed a ‘lift’, as the effect is to increase the hazard rate (HR) function by a constant, which does not, of course, change the shape and hence the turning points of the HR function. However, lifting the HR function does not, in general, mean lowering the corresponding mean residual life (MRL) function by a constant, and so the MRL turning points, unlike those of the HR function are not invariant. The MRL turning points are used in, for example, defining burn‐in procedures in reliability engineering, and determining premiums in insurance. Hence, it is of interest to examine the changes in the shape of the MRL function, and in the locations of its turning points, resulting from a lift in the HR function. We discuss these problems in detail, with reference to a number of common distributions in reliability and mortality modeling. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
328.
Empirical measures generated by random sequences with deterministic and random noises have same asymptotic distributions provided
that the noises have same asymptotic distributions (cf., Davydov and Zitikis, 2004, Proc. Am. Math. Soc. 132, 1203–1210). This phenomenon has raised an intriguing question about the possibility of distinguishing the two types of noises
based only on their asymptotic distributions. In the present paper we suggest an answer to the question by considering asymptotic
variances, and distributions, of the appropriately centered and normalized empirical measures and processes.
In final form 6 January 2005 相似文献
329.
330.