全文获取类型
收费全文 | 266篇 |
免费 | 3篇 |
国内免费 | 2篇 |
专业分类
化学 | 182篇 |
晶体学 | 6篇 |
力学 | 6篇 |
数学 | 40篇 |
物理学 | 37篇 |
出版年
2022年 | 8篇 |
2021年 | 8篇 |
2020年 | 11篇 |
2019年 | 12篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 7篇 |
2015年 | 12篇 |
2014年 | 14篇 |
2013年 | 29篇 |
2012年 | 16篇 |
2011年 | 19篇 |
2010年 | 25篇 |
2009年 | 16篇 |
2008年 | 21篇 |
2007年 | 15篇 |
2006年 | 10篇 |
2005年 | 10篇 |
2004年 | 6篇 |
2003年 | 7篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1999年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1993年 | 1篇 |
1989年 | 1篇 |
排序方式: 共有271条查询结果,搜索用时 117 毫秒
131.
Fatma Arslan Martin Behrendt Werner Ernst Eberhard Finckh Gunther Greb Friedrich Gumbmann Martin Haller Stefan Hofmann Ralf Karschnick Matthias Klein Wolfgang Kretschmer Jochen Mackiol Gerhard Morgenroth Christian Pagels Markus Schleicher 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》1995,107(2):205-207
132.
Sensitivity enhancement of indium determination by flame atomic absorption spectrometry (FAAS) was achieved; using a slotted quartz tube (SQT-FAAS) and slotted quartz tube atom trap (SQT-AT-FAAS). SQT was used as an atom trap (AT) where the analyte is accumulated in its inner wall prior to re-atomization. The signal is formed after re-atomization of analyte on the trap surface by introduction of 10 μL of isobutyl methyl ketone (IBMK). Sensitivity was improved 400 times using SQT-AT-FAAS system with respect to conventional FAAS and 279 times with respect to SQT-FAAS without any collection. Characteristic concentration (C0) and limit of detection values were found to be 3.63 ng mL−1 and 2.60 ng mL−1, respectively, using a sample flow rate of 7.0 mL min−1 and a collection period of 5.0 min. In addition, interference effects of some elements on indium signal were studied. In order to characterize indium species trapped, X-ray Photoelectron Spectrometry (XPS) was utilized and it was found that indium was collected on the inner surface of SQT as In2O3. The accuracy of the procedure was checked to determine indium in the standard reference material (Montana Soil, SRM 2710). 相似文献
133.
Two new vic-dioxime ligands bearing an important redox-active substituent, anti-β-ferrocenylethylaminoglyoxime (1a) and anti-β-ferrocenylethylaminophenylglyoxime (1b), have been synthesized, and their Ni(II), Cu(II) and Co(II) (2a-4a, 2b-4b) complexes were obtained. The composition and structure of the products were determined by elemental analysis, Fourier transform infrared (FT-IR), ultraviolet-visible (UV-vis), mass spectrometry (MS), one-dimensional (1D) 1H, 13C NMR, and two-dimensional (2D) heteronuclear multiple bond correlation (HMBC) techniques. The redox behaviors of the ligands and their complexes were investigated by cyclic voltammetry (CV), which revealed that all the ferrocenyl redox centers are electrochemically independent and undergo a quasi-reversible oxidation at similar potentials. Also, antibacterial activity was studied against Staphylococcus aureus ATCC 29213, Streptococcus mutans RSHM 676, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853. The antimicrobial test results indicated that all the compounds have mild levels of antibacterial activity against both gram negative and gram-positive bacterial species. 相似文献
134.
Ummahan Ege Arslan brahim lker Aka Gülümsen Onarl Irmak Osman Avcolu 《Mathematical Methods in the Applied Sciences》2019,42(16):5293-5304
In this study, we mainly show that the functor from the category X2Mod of 2‐crossed modules of groups to the category Groups of groups assigning to each 2‐crossed module the group P, and to each 2‐crossed module morphism the group homomorphism f0 is a fibration. In addition, we study some related properties. 相似文献
135.
Shrink fits are found frequently in mechanical engineering as an efficient means of connecting a cylindrical inclusion with an annular hub. For reliable operation, the interface pressure between the components should be as large as possible. Although in some cases this may be achieved by a partially plastic design, there are many applications where the device should behave elastically. In the present study, the use of a functionally graded material for the hub is proposed, and particularly an annular inclusion is considered. It is shown that – depending on the radii ratios and the degree of grading – qualitatively different types of mechanical behavior are possible, and that in general by appropriate grading a much better performance at rotation can be achieved, accompanied by a substantial saving of weight. These issues are discussed in detail, and the analytically obtained results provide a comprehensive means for the practicing engineer to decide whether this type of shrink fit might be advantageous for some applications. 相似文献
136.
The influence of the LT-AlN(NL) growth times on the mosaic structure parameters of the AlN layer grown on the LT-AlN(NL)/6H-SiC structures as well as the dislocation densities and the strain behaviours in the AlN epilayers has been investigated using XRD measurements. The growth times of the LT-AlN(NL) were changed to 0, 60, 120, 180, and 240?s. We observed that the mosaic structure parameters of the AlN epilayers were slightly affected by the LT-AlN(NL) growth times. However, the dislocation densities in the AlN layer are affected by the growth times of the LT-AlN(NL) layer. The highest edge dislocation density (5.48?×?1010?±?2.3?×?109?cm?2) was measured for the sample in which 120?s grown LT-AlN(NL) was used. On the other hand, highest screw type dislocation density (1.21?×?1010?±?1.7?×?109?cm?2) measured in the sample E that contains 240?s growth LT-AlN(NL). The strain calculation results show that the samples without LT-AlN(NL) suffered maximum compressive in-plane strain (?10.9?×?10?3?±?1.8?×?10?4), which can be suppressed by increasing the LT-AlN(NL) growth times. The out-of-plane strain also has a compressive character and its values increase with LT-AlN(NL) growth times between 60 and 180?s. Same out-of-plane strain values were measured for the LT-AlN(NL) growth times of 180 and 240?s. Furthermore, the form of the biaxial stress in the AlN epilayer changed from compressive to tensile when the LT-AlN(NL) growth times were greater than 120?s. 相似文献
137.
Optics and Spectroscopy - The optical penetration depth is one of the important parameters needed for the calculations of light dosimetry in various medical applications like photodynamic therapy.... 相似文献
138.
139.
140.
Arslan A Kiralp S Toppare L Bozkurt A 《Langmuir : the ACS journal of surfaces and colloids》2006,22(6):2912-2915
Biosensor construction and characterization studies of poly(acrylic acid) (PAA) and poly(1-vinyl imidazole) (PVI) complex systems have been carried out. The biosensors were prepared by mixing PAA with PVI at several stoichiometric ratios, x (molar ratio of the monomer repeat units). The enzyme, invertase, was entrapped in the PAA/PVA interpenetrating polymer networks during complexation. Modifications were made on the PAA/PVI conducting polymer electrolyte matrixes to improve the stability and performance of the polymer electrolyte-based enzyme biosensor. The maximum reaction rate (V(max)) and Michaelis-Menten constant (K(m)) were investigated for the immobilized invertase. The temperature and pH optimization, operational stability, and shelf life of the polymer electrolyte biosensor were also examined. 相似文献