全文获取类型
收费全文 | 808篇 |
免费 | 53篇 |
国内免费 | 14篇 |
专业分类
化学 | 560篇 |
晶体学 | 7篇 |
力学 | 38篇 |
数学 | 123篇 |
物理学 | 147篇 |
出版年
2023年 | 3篇 |
2022年 | 24篇 |
2021年 | 40篇 |
2020年 | 37篇 |
2019年 | 45篇 |
2018年 | 54篇 |
2017年 | 61篇 |
2016年 | 69篇 |
2015年 | 44篇 |
2014年 | 43篇 |
2013年 | 91篇 |
2012年 | 85篇 |
2011年 | 73篇 |
2010年 | 43篇 |
2009年 | 33篇 |
2008年 | 19篇 |
2007年 | 29篇 |
2006年 | 20篇 |
2005年 | 8篇 |
2004年 | 15篇 |
2003年 | 6篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1979年 | 2篇 |
排序方式: 共有875条查询结果,搜索用时 473 毫秒
11.
This paper presents a method for the construction of a graphene paste electrode (GPE) from reduced graphene oxide (RGO). The GPE was successfully used for the determination of medetomidine. The influence of some experimental variables such as pH, supporting electrolyte, scan rate, and possible interferences were studied. Differential pulse voltammetric (DPV) peak currents of medetomidine increased linearly with its concentration in the range from 0.009 to 2.5 µM. The limit of detection (LOD) and limit of quantitation (LOQ) values for the determination of medetomidine were 2.8 and 9.2 nM, respectively. Also, for the first time, the electroreduction behavior of medetomidine was investigated. 相似文献
12.
13.
Synthesis of Depo‐Medrol–chitosan hydrogel as new drug slow‐release appliance and investigation of release kinetics by high‐performance liquid chromatography
下载免费PDF全文
![点击此处可从《Biomedical chromatography : BMC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Reza Alizadeh Sara Majd Jabbari Amir H. Zarnani Hamidreza Barghi 《Biomedical chromatography : BMC》2016,30(9):1346-1353
The present study deals with preparation and optimization of a novel chitosan hydrogel‐based matrix by suspension cross‐linking method for controlled release of Depo‐Medrol. The controlled release of Depo‐Medrol for effective Rheumatoid arthritis disease has become an imperative field in the drug delivery system. In this context, it was intended to optimize loading circumstances by experimental design and also study the release kinetics of Depo‐Medrol entrapped in the chitosan matrix in order to obtain maximal efficiency for drug loading. The optimum concentrations of chitosan (2.5 g), glutaraldehyde (3.05 μL) and Depo‐Medrol (0.1 mg) were set up to achieve the highest value of drug loaded and the most sustained release from the chitosan matrix. In vitro monitoring of drug release kinetic using high‐performance liquid chromatography showed that 73% of the Depo‐Medrol was released within 120 min, whereas remained drug was released during the next 67 h. High correlation between first‐order and Higuchi's kinetic models indicates a controlled diffusion of Depo‐Medrol through the surrounding media. Moreover, recovery capacity >82% and entrapment efficiency of 58–88% were achieved under optimal conditions. Therefore, the new synthesized Depo Medrol–chitosan is an applicable appliance for arthritis therapy by slow release mechanism. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
14.
15.
Movlaee Kaveh Beitollahi Hadi Ganjali Mohammad Reza Norouzi Parviz 《Mikrochimica acta》2017,184(9):3281-3289
Microchimica Acta - A carbon paste electrode (CPE) was modified with graphene and ethyl 2-(4-ferrocenyl-[1,2,3]triazol-1-yl) acetate (EFTA) and used for electrocatalytic oxidation of levodopa.... 相似文献
16.
Alamdarlo Farzad Vaziri Solookinejad Ghahraman Zahakifar Fazel Jalal Masoud Rezvani Jabbari Masoud 《Journal of Radioanalytical and Nuclear Chemistry》2021,329(2):1033-1043
Journal of Radioanalytical and Nuclear Chemistry - In this work, graphene oxide (GO) and (aminomethyl)phosphonic acid–Graphene oxide (AMPA–GO) adsorbents were prepared by the modified... 相似文献
17.
Mahasin F. Hadi Al-Kadhemy 《Physica B: Condensed Matter》2012,407(17):3335-3338
The influence of the thickness of CdTe/n-Ge heterojunction photodetectors on I–V curves was studied experimentally and theoretically. The thicknesses of the CdTe thin films were 110, 130, 150, and 200 nm. The power intensity of illumination was 150 mW/cm2. Increasing the thickness led to an increase in photocurrent. 相似文献
18.
Hadi Amiri Amir Charkhi Mohammad Ali Moosavian Seyyed Javad Ahmadi Hamed Nourian 《Chemical Papers》2017,71(9):1587-1596
The polydimethylsiloxane (PDMS) mixed matrix membrane with dispersed phase of nanozeolite silicalite-1 has been synthesized on polyethersulphone (PES) as a support, and its performance in the gas separation of xenon and krypton has been studied. For this purpose, nanozeolite silicalite-1 is synthesized by the hydrothermal clear solution method and is characterized by XRD and SEM analysis. In this research, the separation performance of MMM has also been compared with the polymeric PDMS membrane. Furthermore, the effect of feed pressure and loading percentage of nanozeolite in the polymeric matrix are evaluated. The results indicate that the addition of nanozeolite to the polymeric matrix improves its separation performance, and that the changes of the feed pressure have no major effect. The average permeability of the krypton and xenon gases through the PDMS polymeric membrane is calculated as 1.25 × 10?9 and 1.78 × 10?9 cm mol/(cm2 s kPa), respectively, while by adding only 5 wt% of nanosilicalite-1 to the polymeric matrix of the membrane, this amount increased to 1.82 × 10?9 and 8.07 × 10?9 cm mol/(cm2 s kPa), respectively. In addition, the presence of nanosilicalite-1 as the filler leads to an increase in the selectivity of xenon to krypton up to 4.38. 相似文献
19.
Karim Akbari Dilmaghani Behzad Zeynizadeh Hadi Parasajam 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):544-553
Abstract Various 3,4-dihydropyrimidin-2-(1H)-ones (DHPMs) and their sulfur derivatives were efficiently synthesized by a one-pot cyclocondensation reaction of aromatic and aliphatic aldehydes, β-dicarbonyl compounds and urea (or thiourea) in the presence of sulfuric acid immobilized on activated charcoal (133% w/w). The reactions were carried out in refluxing n-hexane-acetonitrile (2.5:0.5 mL) within 5–150 min to give 3,4-dihydropyrimidinones (or thiones) in high to excellent yields (81–97%). 相似文献
20.
A spatially intermittent polymerization (SIP) reactor has been used for determination of absolute rate constants in photo-initiated, free-radical polymerization of styrene (STY) and methyl methacrylate (MMA). Experimental data are reported in the temperature range 15-30°C and in the high molecular weight region for MMA and STY. Additional experimental data are reported at 30° C and various lower molecular weights for STY which indicate that the propagation rate constant K is independent of polymer molecular weight, and K is dependent on molecular weight, especially at low molecular weight, approaching an approximately constant value at high molecular weight. 相似文献