全文获取类型
收费全文 | 835篇 |
免费 | 42篇 |
国内免费 | 15篇 |
专业分类
化学 | 290篇 |
晶体学 | 3篇 |
力学 | 44篇 |
综合类 | 1篇 |
数学 | 104篇 |
物理学 | 450篇 |
出版年
2024年 | 2篇 |
2023年 | 21篇 |
2022年 | 11篇 |
2021年 | 8篇 |
2020年 | 8篇 |
2019年 | 14篇 |
2018年 | 16篇 |
2017年 | 26篇 |
2016年 | 32篇 |
2015年 | 25篇 |
2014年 | 45篇 |
2013年 | 55篇 |
2012年 | 24篇 |
2011年 | 61篇 |
2010年 | 35篇 |
2009年 | 63篇 |
2008年 | 47篇 |
2007年 | 59篇 |
2006年 | 43篇 |
2005年 | 41篇 |
2004年 | 41篇 |
2003年 | 38篇 |
2002年 | 25篇 |
2001年 | 22篇 |
2000年 | 15篇 |
1999年 | 16篇 |
1998年 | 21篇 |
1997年 | 19篇 |
1996年 | 9篇 |
1995年 | 10篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有892条查询结果,搜索用时 46 毫秒
41.
《Electroanalysis》2017,29(12):2752-2756
Chloride containing reference electrodes, such as various silver‐silver chloride electrodes, are well established in electrochemical analyses. Usually less attention is paid to the influence of potential chloride contamination of electrochemical measurements. Herein, the impact of the chloride leakage rate is studied by means of experiments concerning the anodic oxidation of aluminum. Based on the results, the authors determine critical leakage rates, depending on typical electrolyte volumes and experimental conditions. The results demonstrate that chloride leakage can significantly influence electrochemical measurements, even at ultra‐low leakage rates. A guideline for the usage of chloride containing reference electrodes is deduced from the experimental results and theoretical considerations. 相似文献
42.
Maria Catarina Coutinho Varela da Silva João Luís Maia Figueirinhas 《Liquid crystals》2016,43(1):124-130
A number of polymer dispersed liquid crystal (PDLC) films based on dimethacrylate monomers were synthesised by polymer-induced phase separation (PIPS) using polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether (TX-100) as an additive up to total solution weight of 10% aiming to modify the initial anchorage force of the liquid crystal (LC) molecules to the polymeric matrix. The effects of the addition of this additive to the PDLC films were studied resorting to electro-optical studies. Using a fitting model, several parameters were correlated such as the permanent memory effect (PME), the voltage required to achieve 90% of maximum transmittance (E90), the average elastic constant (K) and the rotational viscosity of the director (γ). The use of TX-100 results on an increase on the PME and γ, and decrease on the E90 and K. 相似文献
43.
44.
M. Rösslein 《Accreditation and quality assurance》2000,5(3):88-94
This paper reviews the so-called "component by component approach" of evaluating measurement uncertainty. An overview of
the evaluation process is given followed by an in-depth discussion of some of the differences between this approach and the
approach of utilising validation data. Some of the advantages and disadvantages of using the component by component approach
are outlined at the end.
Received: 4 August 1999 · Accepted: 11 November 1999 相似文献
45.
This paper describes the application of a novel broadband acoustic sensor to evaluating the acoustic emissions from cavitation produced by a typical commercial 20 kHz sonochemical horn processor. Investigations of the reproducibility of the processor, and of the variation in cavitation emissions as a function of output setting and sensor location are described, and resulting trends discussed in terms of the broadband integrated power in the megahertz frequency range. Companion studies with a conventional membrane hydrophone have illustrated for the first time that cavitation emissions produced by a sonochemical horn processor can extend to frequencies beyond 20 MHz, and the sensor shows that significant nonlinearity can be seen in measured cavitation activity with increasing nominal output power. 相似文献
46.
There are various methods to evaluate voice parameters. Original software was used to assess the voice quality by the staff of AUDIO-Fon centr Brno, Czech Republic. A group of hereditary deaf persons was examined. Deaf persons have all of the biological conditions to make voice except for the possibility of acoustic feedback. We examined the voices of 35 persons (20 men and 15 women) with hereditary profound hearing impairments, and we compared voice parameters with the voice of intact persons. To measure we used special software called voice field measurements (VFMs). The program graphically records voice frequency and intensity. VFM is an objective method that enables the assessment of basic physical voice characteristics. It is suitable for the examination of both intact and disturbed voice. The voice of the deaf has a higher basic voice frequency in men as well as in women. This type of voice production, ie, childlike voice, which is fixed only by a motor stereotype, is much more demanding for a mature larynx. Hearing influences both the voice development and speech production. The voice of persons with hearing impairments has a higher basic voice frequency regardless of their sex. This type of voice production, which is fixed only by a motor stereotype, ie, child voice, is much more demanding for a larynx of an adult. Thus, phonation of deaf people is more demanding and their voice production needs greater effort. Deaf people, despite an intact phonic apparatus, cannot produce more than one type of voice. They cannot modulate their voices concerning the frequency and dynamics. They cannot change their voices continually. The voice is limited in both of these parameters (frequency and dynamics). If a deaf person wants to change a voice characteristic, it is possible only by discontinuous changes-"skipping." 相似文献
47.
Ilya?KuselmanEmail author Alexander?Weisman Wolfhard?Wegscheider 《Accreditation and quality assurance》2003,8(11):530-531
The current situation in the pharmaceutical industry is discussed, when the traceability of measurement (analytical) results to certified values of pharmacopoeial reference standards is required, without evaluating their uncertainties. It is shown that the evaluation of measurement uncertainty is necessary for understanding the level of confidence of the analytical results and their comparability, particularly during preparation and characterisation of the reference standards.Papers published in this section do not necessarily reflect the opinion of the Editors, the Editorial Board and the Publisher. Apart from exceptional circumstances, they are not submitted to the usual referee procedure and go essentially unaltered. 相似文献
48.
49.
50.