全文获取类型
收费全文 | 320篇 |
免费 | 24篇 |
专业分类
化学 | 264篇 |
晶体学 | 4篇 |
力学 | 4篇 |
数学 | 14篇 |
物理学 | 58篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 21篇 |
2021年 | 60篇 |
2020年 | 22篇 |
2019年 | 25篇 |
2018年 | 8篇 |
2017年 | 11篇 |
2016年 | 29篇 |
2015年 | 15篇 |
2014年 | 15篇 |
2013年 | 28篇 |
2012年 | 21篇 |
2011年 | 19篇 |
2010年 | 11篇 |
2009年 | 7篇 |
2008年 | 10篇 |
2007年 | 8篇 |
2006年 | 3篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1988年 | 1篇 |
1917年 | 2篇 |
排序方式: 共有344条查询结果,搜索用时 187 毫秒
91.
Rinda Hedwig Wahyu Setia Budi Syahrun Nur Abdulmadjid Marincan Pardede Maria Margaretha Suliyanti Tjung Jie Lie Davy Putra Kurniawan Koo Hendrik Kurniawan Kiichiro Kagawa May On Tjia 《Spectrochimica Acta Part B: Atomic Spectroscopy》2006,61(12):1285-1293
The applicability of spectrochemical analysis for liquid and powder samples of minute amount in the form of thin film was investigated using ultraviolet Nd-YAG laser (355 nm) and low-pressure ambient air. A variety of organic samples such as commercial black ink usually used for stamp pad, ginseng extract, human blood, liquid milk and ginseng powder was prepared as film deposited on the surface of an appropriate hard substrate such as copper plate or glass slide. It was demonstrated that in all cases studied, good quality spectra were obtained with very low background and free from undesirable contamination by the substrate elements, featuring ppm or even sub-ppm sensitivity and worthy of application for quantitative analysis of organic samples. The proper preparation of the films was found to be crucial in achieving the high quality spectra. It was further shown that much inferior results were obtained when the atmospheric-pressure (101 kPa) operating condition of laser-induced breakdown spectroscopy or the fundamental wavelength of the Nd-YAG laser was employed due to the excessive or improper laser ablation process. 相似文献
92.
Mokashi Imran Khan Sher Afghan Abdullah Nur Azam Bin Azami Muhammad Hanafi Afzal Asif 《Journal of Thermal Analysis and Calorimetry》2020,141(6):2555-2571
Journal of Thermal Analysis and Calorimetry - The use of Li-ion battery in electric vehicles is becoming extensive in the modern-day world owing to their high energy density and longer life. But... 相似文献
93.
94.
95.
This study numerically demonstrates the effects of partial band gaps on the negative refraction properties of sonic crystal. The partial band gap appearing at the second band edge leads to the efficient transmissions of scattered wave envelopes in the transverse directions inside triangular lattice sonic crystal, and therefore enhances the refraction property of sonic crystal. Numerical simulation results indicate a diagonal guidance of coupled scattered wave envelopes inside crystal structure at the partial band gap frequencies and then output waves are restored in the vicinity of the output interface of sonic crystal by combining phase coherent scattered waves according to Huygens' principles. This mechanism leads to two operations for wavefront engineering: one is spatial wavefront shifting operation and the other is convex–concave wavefront inversion operation. The effects of this mechanism on the negative refraction and wave focalization are investigated by using the finite difference time domain(FDTD) simulations. This study contributes to a better understanding of negative refraction and wave focusing mechanisms at the band edge frequencies, and shows the applications of the slab corner beam splitting and SC-air multilayer acoustic system. 相似文献
96.
Discharge current distributions generated underwater by spark discharges from the atmosphere to free water surfaces with conductivities in the range 0.07–10.0 S/m were investigated using a laboratory-scale electrode system consists of a discharge electrode and nine underwater grounding electrodes. Discharge emission on the water surface, which shows significant change with slight increase in conductivity, affects the current distribution in the water. The electric potential of the water surface also changes significantly with slight increase in conductivity. Results of numerical calculations of the underwater discharge current based on the water surface potential agree with the experimental results. 相似文献
97.
Esen Ayse Nur Haciyakupoglu Sevilay Erenturk Sema 《Journal of Radioanalytical and Nuclear Chemistry》2018,315(3):677-683
Journal of Radioanalytical and Nuclear Chemistry - Proficiency testing is an important way of evaluating the analytical method used in the laboratory. In recent years, neutron activation analysis... 相似文献
98.
This study investigated the properties of immobilized β-galactosidase on polymeric beads having Schiff base. Polystyrene microspheres attached L-Alanine (FMPS-Ala) was synthesized from (4-formyl-3-methoxyphenoxymethyl)polystyrene (FMPS) and L-alanine by condensation. A coordinasyon polymer involving Ni2+(FMPS-Ala-Ni) was produced with the template method and characterized. β-galactosidase was immobilized onto the (FMPS), (FMPS-Ala) and (FMPS-Ala-Ni) complexes via covalent bonds. The Km/Vmax values were calculated as 0.343 mM/0.0259 mM min?1for free β-galactosidase and 0.104 mM/0.0126 mM min?1, 0.0617 mM/0.0417 mM min?1and 0.210 mM/0.0287 mM min?1for β-galactosidase immobilized to the (FMPS), (FMPS-Ala) and (FMPS-Ala-Ni) supports, respectively. The storage stability of (FMPS-Ala-Ni) was determined to be higher than that of the (FMPS) and (FMPS-Ala) polymers. 相似文献
99.
Hakan Çiftçi Hasan Nur Testereci Zeki Öktem 《Russian Journal of Electrochemistry》2013,49(12):1160-1164
Conducting poly(2-aminothiazole) (PAT) films were electrodeposited on a platinum disc electrode surface by constant potential electrolysis of 2-aminothiazole (AT) for the stripping voltammetric determination of Ag(I). Ag(I) was preconcentrated on the polymer matrix by dipping the modified Pt electrode (PAT-Pt electrode) into Ag(I)(aq) solution. Effects of the film thickness, reduction potential, pH, preconcentration time, Ag(I) concentration and the interference of some other metal ions on the oxidation peak current of silver were studied. Cu(II) interference observed to be significant for the stripping voltammetric determination of Ag(I). The detection limit was calculated on the basis of signal to noise ratio of 3 as 2 × 10?7 mol L?1. 相似文献
100.
Preparation of Anatase Hollow TiO2 Spheres and Their Photocatalytic Activity in the Photodegradation of Chlorpyrifos 下载免费PDF全文
Afrouz Baharvand Rusmidah Ali Alias Mohd Yusof Akos Noel Ibrahim Sheela Chandren Hadi Nur 《中国化学会会志》2014,61(11):1211-1216
Hollow anatase titania (TiO2) spheres were synthesized using fructose and tetrabutyl titanate (Ti(OC4H9)4, TBT) as the precursors via the conventional hard template method. The morphological, structural and thermal properties of the products were characterized using scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG‐DTA), Brunauer? Emmett? Teller (BET) surface area analysis and diffuse reflectance ultraviolet visible (DR UV? Vis) spectroscopy. XRD revealed that the hollow TiO2 prepared was in the anatase phase and the BET surface area measured was about 22 m2 g?1. The photocatalytic activity of the synthesized hollow anatase TiO2 in the photodecomposition of chlorpyrifos was 18.67 % higher than that obtained using commercial TiO2. 相似文献