全文获取类型
收费全文 | 925篇 |
免费 | 190篇 |
国内免费 | 64篇 |
专业分类
化学 | 833篇 |
晶体学 | 42篇 |
力学 | 3篇 |
综合类 | 3篇 |
数学 | 3篇 |
物理学 | 295篇 |
出版年
2024年 | 4篇 |
2023年 | 8篇 |
2022年 | 33篇 |
2021年 | 27篇 |
2020年 | 40篇 |
2019年 | 34篇 |
2018年 | 27篇 |
2017年 | 22篇 |
2016年 | 58篇 |
2015年 | 46篇 |
2014年 | 64篇 |
2013年 | 101篇 |
2012年 | 62篇 |
2011年 | 46篇 |
2010年 | 38篇 |
2009年 | 41篇 |
2008年 | 51篇 |
2007年 | 43篇 |
2006年 | 53篇 |
2005年 | 38篇 |
2004年 | 32篇 |
2003年 | 39篇 |
2002年 | 48篇 |
2001年 | 21篇 |
2000年 | 33篇 |
1999年 | 17篇 |
1998年 | 35篇 |
1997年 | 22篇 |
1996年 | 27篇 |
1995年 | 17篇 |
1994年 | 11篇 |
1993年 | 4篇 |
1992年 | 8篇 |
1991年 | 8篇 |
1990年 | 9篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1981年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有1179条查询结果,搜索用时 15 毫秒
11.
富镉Hg_(1-x)Cd_xTe是一种新型的光电转换材料,已用于固体结太阳能光伏电池:ITO/CdS/Hg_(1-)Cd_xTe/Au。我们曾对Hg_(1-x)Cd_xTe的电沉积机理作过研究。最近我们用电沉积制备的Hg_(0.09)Cd_(0.91)Te多晶薄膜做成了液体结太阳能光电化学电池并观察到明显光电响应。 相似文献
12.
邻羟基萘基荧光酮-DDMBA光度法测定微量锗 总被引:1,自引:0,他引:1
邻羟基萘基荧光酮-DDMBA光度法测定微量锗冯永兰,邝代治(衡阳师范专科学校化学系衡阳,421008)关键词:分光光度法,锗,邻羟基萘基荧光酮,溴化十二烷基二甲基苄铵苯基荧光酮类试剂应用于锗的测定已有报导 ̄[1-6]。但邻羟基萘基荧光酮(β-HNF)... 相似文献
13.
Yu. E. Roginskaya F. Kh. Chibirova T. L. Kulova A. M. Skundin 《Russian Journal of Electrochemistry》2006,42(4):355-362
Products of lithium interaction with thin-film nanostructured SnO2-TiO2 (ST) oxides are studied with the aid of x-ray diffraction analysis and Moessbauer spectroscopy on the 119Sn nuclei. Electrochemical properties of a series of the ST electrodes with different concentrations of TiO2 varied from 0 to 20 mol % are also examined. It is concluded that the specific feature of the charge-discharge mechanism of the ST electrodes is a significant participation of oxygen in reversible reactions during insertion and extraction of lithium as compared with an alloying mechanism of operation of tin-containing anodes. The leading role in this is played by titanium oxide. Remaining stable towards reduction by lithium, it facilitates the holding of the neighboring layers of SnO2 in a nanodisperse state and in an oxidized state. The effect of a decrease in the capacity degradation in modified TiO2 electrodes, which is discovered in this work, is attributed to the hampering of the growth of nanocrystallites of β-Sn by interlayers of tin and titanium oxides mentioned above. 相似文献
14.
Synthetic routes for the preparation of Si or Ge nanoclusters as gaseous species, colloids, supported composites, or as unsupported powders are reviewed along with selected characterization data. The optical properties of these and related materials, such as porous Si, are summarized with particular emphasis on photo- or electroluminescence phenomena. Research opportunities related to Si and Ge cluster chemistry are suggested. 相似文献
15.
本采用压缩X因子导数光谱技术实现了宽峰体系灵敏度的大幅度提高,提出了测定痕量锗的方法。在0.72mol/LH2SO4和3.0mol/LH3PO4的混酸介质中,锗-水杨基荧光酮-OP三元显色体系的压缩X因子四阶导数光谱摩尔响应系数达1.89×10^6L.mol^-1.cm^-1,灵敏度比常规光度法高12.4倍;最低检测出限为0.00033mg/L,比常规光谱法低4倍;选择性也进一步提高,绝大多数离 相似文献
16.
Bodnarchuk M. I. Kovalenko M. V. Stroyuk A. L. Kuchmii S. Ya. 《Theoretical and Experimental Chemistry》2004,40(5):287-292
The photochemical behavior of solutions containing a mixture of CdS and CdTe nanoparticles under pulsed irradiation conditions was investigated. It was shown that electron transfer from the CdS particles to the CdTe nanoparticles occurs during the photoexcitation of such systems. The effectiveness of the process is increased with increase in the size of the CdTe nanoparticles. Such behavior is due to decrease in the potential of the CdTe conduction band with increase in the size of the nanoparticles as a result of the appearance of quantum-dimensional effects. 相似文献
17.
苯基荧光酮荧光分光光度法测定痕量锗的研究 总被引:10,自引:0,他引:10
锗具有增血、抗炎症、抗衰老等多种医疗功能 ,因此 ,越来越受到人们的关注。荧光光度法测定微量锗已有报道[1~ 4] 。用苯基荧光酮荧光度法测定锗未见报道。本文利用苯基荧光酮与锗在醋酸 醋酸钠缓冲溶液中络合物形成速度快的优势 ,使其先在缓冲溶液中显色 ,然后在 0 .3mol LHCl介质中测定其荧光强度 ,用于粉煤灰中痕量锗的测定 ,得到满意结果。1 实验部分1 1 仪器与试剂RF - 5 4 0荧光分光光度计 (日本岛津 )。锗标准溶液 ( 1g L) :称取 0 .1 0 0 0g纯锗粉于 5 0ml小烧杯中 ,加入 5mlNaOH ,再加入几滴 30 %H2 O2… 相似文献
18.
Rollie J. Myers 《Journal of solution chemistry》2007,36(3):395-403
We have measured the second acid dissociation constant, K
2a
, at several ionic strengths for hydrogen telluride (H2Te) using the Charge Transfer to Solvent (CTTS) uv spectra of its anions HTe− and Te2−. Since it is produced in our solutions, we have also determined the spectra of Te2
2− both in the uv and in the visible regions. At 25 ∘C, K
2a
= (1.28 ± 0.02) × 10−12 by extrapolation to zero ionic strength. Its value at an ionic strength equal to 0.5 mol.dm-3 was estimated to be (8.7 ± 0.2) × 10−12. The solution thermodynamics of these species are also discussed and comparisons are made to related acids. 相似文献
19.
选择水杨基荧光酮-乳化剂OP-盐酸为显色体系,应用双波长分光光度法扣除硫酸锌的基体干扰,不分离直接测定了湿法炼锌过程中硫酸锌净化液中的痕量锗。测定范围在0-40mg/L。本法应用于株洲冶炼厂锌净化液中锗的测定,结果与该厂长期的萃取-比色法结果相吻合,而测定速度较萃取-比色法至少提高了一倍。 相似文献
20.
Takeuchi Y Nishikawa M Hachiya H Yamamoto H 《Magnetic resonance in chemistry : MRC》2005,43(8):662-664
High-resolution solid-state magic angle spinning (73)Ge NMR spectra of some organogermanium compounds were measured. Most tetrasubstituted germanes with identical substituents exhibited signals except for one case. Tetrasubstituted germanes with two kinds of different but somewhat similar substituents exhibited broad peaks. Trisubstituted germanes failed to show signals, indicating the importance of symmetry around germanium. 相似文献