全文获取类型
收费全文 | 171篇 |
免费 | 14篇 |
国内免费 | 4篇 |
专业分类
化学 | 136篇 |
晶体学 | 2篇 |
力学 | 5篇 |
数学 | 20篇 |
物理学 | 26篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 8篇 |
2020年 | 4篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2017年 | 6篇 |
2016年 | 12篇 |
2015年 | 11篇 |
2014年 | 15篇 |
2013年 | 13篇 |
2012年 | 22篇 |
2011年 | 14篇 |
2010年 | 9篇 |
2009年 | 10篇 |
2008年 | 14篇 |
2007年 | 5篇 |
2006年 | 6篇 |
2005年 | 6篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 2篇 |
1999年 | 1篇 |
1994年 | 1篇 |
排序方式: 共有189条查询结果,搜索用时 46 毫秒
101.
Golamreza Khayatian Hadi Rezatabar Fatemeh Salehy Karonian Abdollah Salimi 《中国化学会会志》2006,53(5):1133-1139
Two new highly selective triiodide electrodes have been prepared using charge‐transfer complex of iodine with cryptand 222 as an electroactive ionophore and nitrophenyl octyl ether as a plasticizing agent. The electrodes showed Nernstian response to triiodide ions over a concentration range from 1.0 × 10?;2 — 7.9 × 10?;7 M and from 1.0 × 10?;2 — 1 × 10?;6 M with detection limits of 6.3 × 10?;7 and 7.9 × 10?;7 M for cryptand and its charge‐transfer complex with iodine, respectively. The response times (t95%) of the sensors were 10 and 5 s. The membrane could be used for more than 1 month without any divergence in potentials. The proposed sensors exhibited very high selectivity for triiodide ion over other anions, and could be used in a wide pH range ?2–10. These electrodes were successfully applied as an indicator electrode in potentiometric titration of copper in ore samples. 相似文献
102.
103.
104.
Abdollah Salimi Loghman Mohamadi Rahman Hallaj Saied Soltanian 《Electrochemistry communications》2009,11(6):1116-1119
For the first time silicon carbide nanoparticles (SiC) was used for electrode modification and electrocatalytic oxidation of insulin. In comparison to bare glassy carbon (GC) electrode, the oxidation of insulin at GC electrode modified with SiC nanoparticles occurred at reduced overpotentials. The modified electrode was applied for insulin detection using cyclic voltammetry, differential pulse voltammetry (DPV) and flow injection analysis (FIA). Flow injection amperometric determination of insulin at this modified electrode yielded a calibration curve with the following characteristics; linear dynamic range up to 600 pM, sensitivity of 710 pA pM?1 cm?2 and detection limit of 3.3 pM. In addition interference effect of the electroactive existing species (uric acid, glucose, lactic acid, l-cysteine and cholesterol) was diminished and for ascorbic acid eliminated by covering the surface of modified electrode with nafion film. This electrode shows many advantages as an insulin sensor such as simple preparation method without using any specific electron transfer mediator or specific reagent, high sensitivity, excellent catalytic activity, short response time, long term stability and remarkable antifouling property toward insulin and its oxidation product. Sensitivity, detection limit and antifouling properties of this insulin sensor are better than all of the reports in the literature for insulin detection at physiological pH solutions. 相似文献
105.
106.
107.
Here, we are describing the study of the chemiluminescence arising from the reaction of bis (2,4,6-trichlorophenyl) oxalate (TCPO) system with new bis [N-(4-pyridyl)-p-toluene sulfonamide] palladium dichloride (BSPC) as a novel luminescent. The optimum concentrations of all reagents such as sodium salicylate (SS) as catalyst, hydrogen peroxide as oxidizing reagent and the relationships between the chemiluminescence intensity and concentrations of TCPO, SS, hydrogen peroxide and BSPC are reported. After optimization the required reagents, the system were used for determination of amino acid lysine, as an effective and selective quencher in the solution functioning in a Stern–Volmer fashion. This resulted in the development of a facile and highly sensitive chemiluminescence detection scheme for the determination of lysine in biological samples. Ultimately, estimating quenching constant K q of 4.29?×?103 M?1 was successfully carried out. Under the optimal conditions, the evaluated lower and upper detection limits of measurable concentration of lysine are 1.17?×?10?7 and 3.18?×?10?4 M, respectively. 相似文献
108.
Abdollah Omrani Mousa Ghaemy Abbas A. Rostami 《Journal of Thermal Analysis and Calorimetry》2009,98(2):477-483
The kinetics and mechanism of cure reaction of DGEBA using a chelate of Ni(II) with diethylenetriamine (dien), Ni(dien)2I2, as a curing agent was studied by DSC. TG curve of the complex curing agent showed mass loss in two region of temperature: 200–320 and 450–550 °C. Dynamic DSC measurements showed only one exothermic peak with a maximum about 250 °C depending on the heating rate. According to the methods of KAS and Ozawa–Flynn–Wall the values of E a were 92.5 and 96.2 kJ/mol, respectively. The isoconversional kinetic analysis in whole range of conversion, α = 0.02–0.95, showed small changes in the E a values in the region of α = 0.04–0.6 and most likely represent some average values (E a = 110 kJ/mol) between the values of E a of non-autocatalyzed and autocatalyzed reactions. Using the sole dependence of E a on α, the time required to reach fully cured materials under isothermal conditions were also predicted and compared with the experimental results. 相似文献
109.
Earlier we reported on the synthesis of α,4-dicarboxy-2-nitrobenyzl caged compounds (Schaper, K. et al. [2002] Eur. J. Org. Chem., 1037–1046). These compounds have the advantage of an increased hydrophilicity compared with the well-established α-carboxy-2-nitrobenzyl caged compounds; however, the release of the active compound becomes slower due to the introduction of the additional carboxy group. Based upon theoretical calculations we predicted that the release would become faster when the additional carboxy group is moved to the 5-position. Here we describe the synthesis and the photochemical and biological characterization of an α,5-dicarboxy-2-nitrobenyzl caged compound. The high hydrophilicity of the new caging group is maintained due to the fact that the additional carboxy moiety is preserved, while the release of the active species from the new derivative is even faster than for the reference, an α-CNB caged compound. 相似文献
110.