全文获取类型
收费全文 | 1684篇 |
免费 | 61篇 |
国内免费 | 18篇 |
专业分类
化学 | 1080篇 |
晶体学 | 36篇 |
力学 | 93篇 |
数学 | 183篇 |
物理学 | 371篇 |
出版年
2024年 | 12篇 |
2023年 | 9篇 |
2022年 | 78篇 |
2021年 | 87篇 |
2020年 | 52篇 |
2019年 | 61篇 |
2018年 | 48篇 |
2017年 | 31篇 |
2016年 | 69篇 |
2015年 | 49篇 |
2014年 | 58篇 |
2013年 | 126篇 |
2012年 | 89篇 |
2011年 | 115篇 |
2010年 | 61篇 |
2009年 | 65篇 |
2008年 | 54篇 |
2007年 | 73篇 |
2006年 | 58篇 |
2005年 | 49篇 |
2004年 | 31篇 |
2003年 | 28篇 |
2002年 | 36篇 |
2001年 | 15篇 |
2000年 | 21篇 |
1999年 | 16篇 |
1998年 | 14篇 |
1997年 | 14篇 |
1996年 | 11篇 |
1995年 | 8篇 |
1994年 | 15篇 |
1993年 | 18篇 |
1992年 | 17篇 |
1991年 | 17篇 |
1990年 | 12篇 |
1989年 | 9篇 |
1988年 | 16篇 |
1987年 | 17篇 |
1986年 | 10篇 |
1985年 | 11篇 |
1984年 | 17篇 |
1983年 | 8篇 |
1982年 | 13篇 |
1981年 | 15篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1975年 | 10篇 |
1967年 | 7篇 |
排序方式: 共有1763条查询结果,搜索用时 15 毫秒
101.
Anju Goyal Aditya Sharma Jasanpreet Kaur Sapna Kumari Madhukar Garg Rakesh K. Sindhu Md. Habibur Rahman Muhammad Furqan Akhtar Priti Tagde Agnieszka Najda Barbara Banach-Albiska Katarzyna Masternak Ibtesam S. Alanazi Hanan R. H. Mohamed Attalla F. El-kott Muddaser Shah Mousa O. Germoush Hamdan S. Al-malky Salman H. Abukhuwayjah Ahmed E. Altyar Simona G. Bungau Mohamed M. Abdel-Daim 《Molecules (Basel, Switzerland)》2022,27(3)
102.
103.
A simple, efficient, and ecofriendly procedure has been developed for the synthesis of quinoline and its derivatives in a one-pot reaction of aniline with crotonaldehyde or methyl vinyl ketone using phosphomolybdic acid as solid acid catalyst in miceller media. The catalyst was easily recycled and reused. 相似文献
104.
Determination of palladium in synthetic nuclear wastes by differential pulse voltammetry 总被引:1,自引:0,他引:1
V. T. Aher M. M. Palrecha A. V. Kulkarni G. C. Shah 《Journal of Radioanalytical and Nuclear Chemistry》2002,252(3):573-576
A novel method for the determination of palladium in synthetic nuclear waste samples has been developed using a computerized voltammetric analyzer. The electrode system consists of hanging mercury drop electrode (HMDE)/glassy carbon/Ag-AgCl electrode. Various experimental conditions including electrolyte type, pH and concentration have been optimized, leading to a detection limit of 40 ng/ml. The mixture of 4.10-3M citric acid + 2.10-2M ammonia-ammonium chloride buffer + 4.10-3M EDTA was used as a supporting electrolyte at pH 9.0. Standard addition method was employed to determine the concentration of palladium present in the nuclear waste sample. The relative standard deviation of the proposed method was found to be 8% at 40 ng/ml of palladium content. The method is direct, simple, rapid and free from any possible interference. 相似文献
105.
Shamsa Munir Afzal Shah Abdur Rauf Amin Badshah Hidayat Hussain Zia-ur-Rehman Zahoor Ahmad 《Comptes Rendus Chimie》2013,16(12):1140-1146
The present work reports the redox mechanism of 5-hydroxynaphthalene-1,4-dione (HND), commonly known as juglone, in buffered aqueous media having 50% of ethanol. HND followed different mechanistic routes depending upon the pH of the media and more than one pKa were evaluated from the changes in the slope of the Ep vs. pH plot. The change of pH from acidic to neutral conditions was found to switch the mechanism from CEC to EE mechanism. Pulse techniques were utilized to determine the number of electrons involved in the oxidation and/or the reduction step and to ensure the nature of the redox process. Based upon the obtained results, an electrode reaction mechanism was proposed. Computational studies of HND supported the experimental results. UV-Visible spectroscopy was also employed for the detailed characterization of the compound in a wide range of pH and for the determination of its pKa. 相似文献
106.
Improved general correlation for critical heat flux during upflow in uniformly heated vertical tubes 总被引:1,自引:0,他引:1
M. Mohammed Shah 《International Journal of Heat and Fluid Flow》1987,8(4):326-335
An improved version of the author's earlier correlation for CHF in vertical tubes is presented. It is compared with data that include 23 fluids (water, refrigerants, cryogens, chemicals, and liquid metals), tube diameters 0.315 to 37.5 mm, tube length 1.3 to 940 times diameter, mass flux 4 to 29051 kg/m2s, reduced pressures 0.0014 to 0.96, inlet quality −4 to +0.85, and critical quality −2.6 to +1. These data, from 62 independent sources, are also compared with Katto's general correlation and those of Bowring for water and Subbotin for helium. The present correlation shows much better agreement with data. 相似文献
107.
Rabindra N. Roy Lakshmi N. Roy Kathleen A. Allen Casey J. Mehrhoff Isaac B. Henson Jessica M. Stegner Alexis L. Jenkins Ankita A. Shah Stephen D. Rocchio 《Journal of solution chemistry》2012,41(6):1044-1053
In this study, we report the pH values of two buffer solutions without chloride ion and eight buffer solutions with NaCl with an ionic strength I=0.16 mol?kg?1. Electromotive force (emf) techniques have been used to get the cell potentials at 12 temperatures from 5 to 55?°C, including 37?°C. An extended form of the Bates-Guggenheim convention is used in the entire ionic strength range, 0.04 to 0.16?mol?kg?1. The residual liquid junction potentials (??E j ) of the buffer solutions of MOBS have been estimated from previous measurements with a flowing junction cell. These values of ??E j have been used for correction in order to ascertain the operational pH values of four buffer solutions of MOBS at 25 and 37?°C. These solutions are recommended as pH standards for physiological application in the pH range 7.4 to 7.7. 相似文献
108.
109.
In this Letter we investigate the propagation of coupled nonlinear Alfven-spin and helicon-spin waves in a composite medium having the properties of both magnetic and semiconducting materials. We arrive at the nonlinear evolution equations for these coupled waves using the reductive perturbation method for which we obtain soliton solutions. We also discuss the limiting cases for the two materials separately. 相似文献
110.
A simple and sensitive spectrophotometric method has been developed for the determination of sparfloxacin in bulk and pharmaceutical
formulations, and in artificial urine. Sparfloxacin was oxidized into a red colored product using ammonium monovanadate in
acidic media. The proposed method was successfully applied to the determination of sparfloxacin in different pharmaceutical
formulations (tablets) and in a spiked urine sample. The influence of commonly used excipients on the determination of sparfloxacin
was studied. Percentage recoveries in the range of 98.0 ± 0.14 % to 100.0 ± 0.20 % were obtained. The observed data have been
evaluated statistically which showed high accuracy and precision. 相似文献