全文获取类型
收费全文 | 5012篇 |
免费 | 197篇 |
国内免费 | 26篇 |
专业分类
化学 | 3513篇 |
晶体学 | 40篇 |
力学 | 168篇 |
综合类 | 2篇 |
数学 | 491篇 |
物理学 | 1021篇 |
出版年
2024年 | 19篇 |
2023年 | 47篇 |
2022年 | 298篇 |
2021年 | 250篇 |
2020年 | 172篇 |
2019年 | 167篇 |
2018年 | 184篇 |
2017年 | 137篇 |
2016年 | 194篇 |
2015年 | 196篇 |
2014年 | 192篇 |
2013年 | 373篇 |
2012年 | 306篇 |
2011年 | 351篇 |
2010年 | 191篇 |
2009年 | 187篇 |
2008年 | 189篇 |
2007年 | 209篇 |
2006年 | 162篇 |
2005年 | 168篇 |
2004年 | 115篇 |
2003年 | 99篇 |
2002年 | 89篇 |
2001年 | 82篇 |
2000年 | 55篇 |
1999年 | 65篇 |
1998年 | 32篇 |
1997年 | 28篇 |
1996年 | 47篇 |
1995年 | 43篇 |
1994年 | 28篇 |
1993年 | 33篇 |
1992年 | 35篇 |
1991年 | 42篇 |
1990年 | 19篇 |
1989年 | 22篇 |
1988年 | 33篇 |
1987年 | 27篇 |
1986年 | 28篇 |
1985年 | 39篇 |
1984年 | 26篇 |
1983年 | 24篇 |
1982年 | 23篇 |
1981年 | 11篇 |
1980年 | 28篇 |
1979年 | 22篇 |
1978年 | 28篇 |
1977年 | 28篇 |
1976年 | 18篇 |
1968年 | 11篇 |
排序方式: 共有5235条查询结果,搜索用时 0 毫秒
121.
122.
Meena Kumari Upendra Kumar Singh Abbul Bashar Khan Maqsood Ahmad Malik 《Journal of Dispersion Science and Technology》2018,39(10):1462-1468
The effect of bovine serum albumin on the surface properties of IL-type gemini surfactant ([C10-4-C10im]Br2), have been investigated by surface tension method. The critical micelle concentration (CMC) as a function of BSA concentrations at various temperatures was investigated. The CMC of [C10-4-C10im]Br2 increases with increasing the concentration of BSA as well as the temperature of the system. The interfacial parameters viz; maximum surface excess concentration (Γmax), the minimum area per molecule (Amin), and surface pressure at CMC (Πcmc) were calculated. In addition, thermodynamic parameters of adsorption and micellization were evaluated by using surface tension data. The results indicated that the binding of [C10-4-C10im]Br2 to BSA is spontaneous and exothermic in nature. The process is entropy driven and hydrophobic interactions are the major driving forces. 相似文献
123.
H. M. Noor ul Huda Khan Asghar Yi Tan Shuang Shi Dachuan Jiang Shiqiang Qin Jiao Liao Shutao Wen Wei Dong Yao Liu 《Applied Physics A: Materials Science & Processing》2014,115(3):753-757
Small amounts of multicrystalline silicon were melted in an electron beam furnace in different experimental conditions in order to investigate the oxygen evaporation behavior during the electron beam melting (EBM) process. The oxygen content level before and after EBM was determined by secondary ion mass spectroscopy. The oxygen content was reduced from 6.177 to 1.629 ppmw when silicon was melted completely at 15 kW with removal efficiency up to 73.6 %. After that, it decreased continually to <0.0517 ppmw when the refining time exceeded 600 s with a removal efficiency of more than 99.08 %. During the melting process, the evaporation rate of silicon is 1.10 × 10?5 kg/s. The loss of silicon could be reduced up to 1.7 % during oxygen removal process to a desirable figure, indicating EBM is an effective method to remove oxygen from silicon and decrease the loss of silicon. 相似文献
124.
125.
126.
127.
Frontispiece: Facile Conversion of Red Phosphorus into Soluble Polyphosphide Anions by Reaction with Potassium Ethoxide 下载免费PDF全文
128.
Aftab Aslam Parwaz Khan Anish Khan Abdullah M Asiri Heba A Kashmery 《Russian Journal of Physical Chemistry B, Focus on Physics》2018,12(3):412-421
The oxidation of Rizatriptan by diperiodatoargentate(III) has been studied by spectrophotometry at neutral pH. The kinetics of the reaction of Rizatriptan has been shown to principle of non-complementary oxidation steps. The initial step involves the deprotonated of the diperiodatoargentate(III) with the alkali; this rearranges during the displacement of a ligand to give free periodate and takes up another ligand monoperiodateargentate(III), combines with a substrate to endow with an intermediate complex which decomposes within a slow step to provide the final product in the following step with a first-order rate constant. The main product was identified by spot test, Fourier- transform infrared spectroscopy, Nuclear magnetic resonance and Liquid chromatography-mass spectrometry spectrum. A conceivable mechanism including pre equilibrium of adducts development between the complex and reductant was planned from the kinetics study. The rate conditions got from system can clarify all exploratory phenomena, and the activation parameters alongside rate constants of the rate determining step were ascertained. 相似文献
129.
130.
Varadhan Krishnakumar Kesarla Mohan Kumar Badal Kumar Mandal Fazlur-Rahman Nawaz Khan 《Research on Chemical Intermediates》2012,38(8):1881-1892
A simple and green protocol, developed utilizing an efficient, heterogeneous and recyclable catalyst, i.e. zinc oxide nanoparticles (ZnO NPs)-mediated synthesis of N-arylhomophthalimides and benzannelated isoquinolinones, is reported. The structures of the desired products were characterized by FTIR, 1H NMR, 13C NMR, and HRMS techniques. The ZnO NPs exhibited excellent catalytic activity and the proposed methodology is capable of providing the desired products in good yield and purity. 相似文献