全文获取类型
收费全文 | 296篇 |
免费 | 32篇 |
国内免费 | 25篇 |
专业分类
化学 | 242篇 |
力学 | 7篇 |
综合类 | 1篇 |
数学 | 28篇 |
物理学 | 75篇 |
出版年
2023年 | 21篇 |
2022年 | 22篇 |
2021年 | 36篇 |
2020年 | 44篇 |
2019年 | 41篇 |
2018年 | 25篇 |
2017年 | 25篇 |
2016年 | 17篇 |
2015年 | 18篇 |
2014年 | 11篇 |
2013年 | 11篇 |
2012年 | 8篇 |
2011年 | 8篇 |
2010年 | 3篇 |
2009年 | 7篇 |
2008年 | 7篇 |
2007年 | 7篇 |
2006年 | 6篇 |
2005年 | 6篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 1篇 |
2001年 | 7篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有353条查询结果,搜索用时 15 毫秒
101.
新课程必修课教学挖掘教材潜在价值的研究 总被引:1,自引:0,他引:1
高中新课程必修教材(山东科技版)为帮助学生加深理解知识、重视知识形成过程、发挥课后习题能力训练等功能,以及重视情感教育提供了丰富多彩的素材。教学时师生要善于挖掘这些素材的潜在价值。 相似文献
102.
山东科技版高中化学新教材非常重视化学实验改革,化学实验在化学教学中的地位、功能、内容,以及教与学方式等方面都有很大变化。本文就此谈了一些认识。 相似文献
103.
Journal of Visualization - In this paper, the hydrodynamic characteristics associated with oblique water entry of two tandem spheres were experimentally investigated using high-speed photography.... 相似文献
104.
Li Huijun Lyu Jiahui Chen Yan Jian Linhan Li Ruochang Liu Xinghui Dong Xiaoli Ma Chun Ma Hongchao 《Journal of Solid State Electrochemistry》2021,25(3):1083-1092
Journal of Solid State Electrochemistry - Owing to its low cost and plentiful different semiconductor configurations resources, photoelectrocatalysis (PEC) has come into the spotlight in... 相似文献
105.
Haiyan Lyu Suping Wang Ying Jin Rong Shen Jiayun Chen Chunyan Zhu Binbin Chen Caisheng Wu 《Biomedical chromatography : BMC》2020,34(11):e4932
Vitamin D measurements in biological fluids by liquid chromatography–tandem mass spectrometry (LC–MS/MS) have been widely used but remain challenging at very low concentration levels. Rapid, high recovery, sensitive and reliable measurements of vitamin D, as well as its primary metabolites using LC–MS/MS are urgently needed for a routine clinical laboratory. Herein, we reported a novel electrospray LC–MS/MS method for determining vitamin D and its primary metabolites using the supported liquid extraction method to achieve higher recoveries, with optimized pH values to achieve optimal derivatization efficiency for higher sensitivity and selected chromatographic conditions to shorten the separation time. The method has been validated with respect to selectivity, recovery, matrix effects, accuracy and precision, stabilities, carryover and dilution effects. The method has been successfully applied to quantify the VD plasma concentrations of depressive, schizophrenic patients and healthy individuals. The result showed that there were significant differences in plasma VD levels between mental disorder patients with healthy individuals, and the total VD levels in mental disorder patients were much higher than healthy individuals, which might require larger clinical samples for validation. 相似文献
106.
107.
Evaluation of stability of Pr2−xNdxNiO4+δ by thermogravimetry under various oxygen partial pressures
Sakai Mamoru Wang Chengkun Okiba Takashi Soga Haruki Hashimoto Takuya 《Journal of Thermal Analysis and Calorimetry》2020,142(1):139-147
Journal of Thermal Analysis and Calorimetry - The thermodynamic and kinetic stability of Pr2?xNdxNiO4+δ was evaluated by thermogravimetry (TG) under a varying oxygen partial pressure... 相似文献
108.
Several kinds of cyclic silsesquioxane (CSSQ) precursors containing linear siloxane chain were prepared to improve both the mechanical properties of their thin films and the compatibility with heptakis (2,3,6-tri-O-methyl)-β-cyclodextrin (tCD) as a porogen. The precursors were synthesized using a hydrolysis/condensation reaction with 2,4,6,8-tetramethyl-2,4,6,8-tetra (trimethoxysilylethyl) cyclotetrasiloxane (cyclic monomer) and three kinds of linear siloxane monomers. As the linear siloxane chain length increases in the CSSQ precursors, the compatibility between the CSSQ precursor and tCD molecules improved due to the chain flexibility of the precursor. Moreover, the mechanical strength of the CSSQ precursor (4ST37) containing linear tetrasiloxane was the best among the prepared precursors. The enhancement of mechanical property might also be attributed to the content of Si-OH groups as well as the chain flexibility, which could help the crosslinking reaction of Si-OH groups in the film curing process. 相似文献
109.
A. I. Demidov M. S. Kokhatskaya Sun Lyu Bin 《Russian Journal of Applied Chemistry》2005,78(8):1280-1282
The content of sodium carbonate and sodium hydrocarbonate in the active paste of the positive and negative electrodes of a worked-out nickel-iron battery after their prolonged storage in air was determined by means of a conductometric analysis. 相似文献
110.
Synthesis and Modification of Zn‐doped TiO2 Nanoparticles for the Photocatalytic Degradation of Tetracycline 下载免费PDF全文
Shuo Pang Ji‐guo Huang Yun Su Bo Geng Su‐yuan Lei Yu‐ting Huang Cong Lyu Xing‐juan Liu 《Photochemistry and photobiology》2016,92(5):651-657
The synthesis of Zn‐doped TiO2 nanoparticles by solgel method was investigated in this study, as well as its modification by H2O2. The catalyst was characterized by transmission electron microscopy, X‐ray diffraction, Brunauer–Emmett–Teller, UV–visible reflectance spectra and X‐ray photoelectron spectroscopy (XPS). The results indicated that doping Zn into TiO2 nanoparticles could inhibit the transformation from anatase phase to rutile phase. Zn existed as the second valence oxidation state in the Zn‐doped TiO2. Zn‐doped TiO2 that was synthesized by 5% Zn doping at 450°C exhibited the best photocatalytic activity. Then, the H2O2 modification further enhanced the photocatalytic activity. Zn doping and H2O2 modifying narrowed the band gap and efficiently increased the optical absorption in visible region. The optimal degradation rate of tetracycline by Zn‐doped TiO2 and H2O2 modified Zn‐doped TiO2 was 85.27% and 88.14%. Peroxide groups were detected in XPS analysis of H2O2 modified Zn‐doped TiO2, favoring the adsorption of visible light. Furthermore, Zn‐doped TiO2 modified by H2O2 had relatively good reusability, exhibiting a potential practical application for tetracycline's photocatalytic degradation. 相似文献