全文获取类型
收费全文 | 269篇 |
免费 | 13篇 |
国内免费 | 3篇 |
专业分类
化学 | 203篇 |
晶体学 | 5篇 |
力学 | 9篇 |
综合类 | 1篇 |
数学 | 8篇 |
物理学 | 59篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 24篇 |
2021年 | 19篇 |
2020年 | 10篇 |
2019年 | 7篇 |
2018年 | 10篇 |
2017年 | 10篇 |
2016年 | 22篇 |
2015年 | 6篇 |
2014年 | 22篇 |
2013年 | 18篇 |
2012年 | 15篇 |
2011年 | 21篇 |
2010年 | 11篇 |
2009年 | 8篇 |
2008年 | 7篇 |
2007年 | 16篇 |
2006年 | 6篇 |
2005年 | 6篇 |
2004年 | 8篇 |
2003年 | 1篇 |
2002年 | 6篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1974年 | 2篇 |
1971年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有285条查询结果,搜索用时 15 毫秒
1.
A. M. Yusof Z. B. Ikhsan A. K. H. Wood 《Journal of Radioanalytical and Nuclear Chemistry》1994,179(2):277-283
Dissolved inorganic arsenic species were determined in natural waters and selected marine species. Prior to irradiation by NAA samples were preconcentrated and the As(III) and As(V) species separated by APCDT-chloroform extraction. Marine samples were digested by microwave heating. Interpretation of data was achieved by comparing the ratio of As(III)/As(V) in the samples and correlating it with the prevailing environmental conditions. 相似文献
2.
Norimah Yusof A.H. Ainul Hafiza Rozaini M. Zohdi Md Zuki A. Bakar 《Radiation Physics and Chemistry》2007,76(11-12):1767-1770
Radiation at 25 and 50 kGy showed no effect on the acidic pH of the local honey, Gelam, and its antimicrobial property against Staphylococcus aureus but significantly reduced the viscosity. Honey stored up to 2 years at room temperature retained all the properties studied. Radiation sterilized Gelam honey significantly stimulated the rate of burn wound healing in Sprague-Dawley rats as demonstrated by the increased rate of wound contraction and gross appearance. Gelam honey attenuates wound inflammation; and re-epithelialization was well advanced compared to the treatment using silver sulphadiazine (SSD) cream. To enhance further the use of honey in wound treatment and for easy handling, Gelam honey was incorporated into our hydrogel dressing formulation, which was then cross-linked and sterilized using electron beam at 25 kGy. Hydrogel with 6% of honey was selected based on the physical appearance. 相似文献
3.
Haas P Hempstead M Jensen T Kagan H Kass R Behrends S Gentile T Guida JM Guida JA Morrow F Poling R Rosenfeld C Thorndike EH Tipton P Besson D Green J Namjoshi R Sannes F Skubic P Stone R Bortoletto D Chen A Goldberg M Horwitz N Jawahery A Lubrano P Moneti GC Trahern CG van Hecke H Csorna SE Garren L Mestayer MD Panvini RS Word GB Yi X Alam MS Bean A Ferguson T Avery P Bebek C Berkelman K Blucher E Cassel DG Copie T DeSalvo R DeWire JW Ehrlich R Galik RS Gilchriese MG Gittelman B Gray SW 《Physical review letters》1985,55(12):1248-1251
4.
Mohd Jailani Mohd Nor Mohammad Hosseini Fouladi Ahmad Kamal Ariffin 《Applied Acoustics》2008,69(4):343-353
Sound quality is among the main factors that influence customers’ preference for choosing good automobile products. It all started more than 10 years ago and grows up so fast due to high competition in the automotive industries. A-weighted noise levels and sound power are usually utilised to measure the noise but they are not adequate to characterise the impact sound inside a car. The most popular approach to determine sound quality of a product is to define an annoyance or specific index, which involves both subjective and objective evaluations. Subjective and objective tests should be studied concurrently in order to determine the sound quality inside a passenger car. This approach is used in this paper to evaluate vehicle comfort index according to most frequently used sound quality metrics, namely; Zwicker loudness, sharpness, roughness and fluctuation strength. As a result researchers of different fields of automotive acoustics investigations can use this index according to the type of road (international road roughness) without any need to perform time-consuming jury tests. The metrics are correlated with jury test results that show which of them and how much has affected the acoustical comfort of the vehicle. The relation between road roughness and vehicle acoustical comfort index is another point of interest in this research. 相似文献
5.
Emad A. Jaffar Al-Mulla Nor Azowa Bt Ibrahim Kamyar Shameli Mansor Bin Ahmad Wan Md. Zin Wan Yunus 《Research on Chemical Intermediates》2013,39(3):1313-1321
In this study, fatty amides (FAs) synthesized from palm olein were used to extract and separate Mo(VI) from acidic media. Effects of various parameters upon the separation of Mo(VI) from Co(II), Ni(II), Al(III) and Mn(II), including extractant concentration, metal ion concentration, contact time, diluent, and acidity, were investigated. It was found that Mo(VI) was successfully separated from the above commonly associated metal ions by stripping from the loaded organic phase. Different acidic and alkaline solutions were used. Ammonium hydroxide solution was an optimal. Extraction of Mo(VI) into the organic phase involved the formation of 1:3 complexes. This work presents the development of a low-cost and environmentally friendly extractant to recycle and recover molybdenum. 相似文献
6.
Yusof Enis Nadia Md. Ishak Nurul N. M. Latif Muhammad A. M. Tahir Mohamed I. M. Sakoff Jennette A. Page Alister J. Tiekink Edward R. T. Ravoof Thahira B. S. A. 《Research on Chemical Intermediates》2020,46(4):2351-2379
Research on Chemical Intermediates - A series of tridentate ONS Schiff bases were synthesised via condensation by reacting 2,3-dihydroxybenzaldehyde with S-2-methylbenzyldithiocarbazate (S2MBDTC)... 相似文献
7.
Khoja Asif Hussain Anwar Mustafa Shakir Sehar Mehran Muhammad Taqi Mazhar Arslan Javed Adeel Amin Nor Aishah Saidina 《Research on Chemical Intermediates》2020,46(8):3817-3833
Research on Chemical Intermediates - The excess emission of greenhouse gases (GHGs) such as CO2 and CH4 is posing an acute threat to the environment, and efficient ways are being sought to utilize... 相似文献
8.
Dr. Kai Lin Woon Siti Aisyah Syaerah Mustapa Nor Shafiq Mohd Jamel Dr. Vannajan Sanghiran Lee Muhammad Zhafran Zakaria Dr. Azhar Ariffin 《Chemphyschem》2020,21(22):2620-2626
Material designs that use donor and acceptor units are often found in organic optoelectronic devices. Molecular level insight into the interactions between donors and acceptors are crucial for understanding how such interactions can modify the optical properties of the organic optoelectronic materials. In this paper, tris(4-(tert-butyl)phenyl)amine (pTPA) was synthesized as a donor in order to compare with unmodified triphenylamine (TPA) in a donor–acceptor system by having 2,4,6-triphenyl-1,3,5-triazine (TRZ) as an acceptor. Dimerization of donors and acceptors occurred in solvent when the concentration of solute is high. At 0 K, using a polarizable continuum model, the nitrogen atom of TPA is found to stack on top of the center of triazine of TRZ, whereas such alignment is offset in pTPA and TRZ. We attributed such alignment in TPA-TRZ as the result of attractive interactions between partial localization of 2pz electrons at the nitrogen atom of TPA and the π deficiency of triazine in TPA-TRZ. By taking into account random motions of the solvent effect at 300 K in quantum molecular dynamics and classical molecular dynamics simulations to interpret the marked difference in emission spectra between TPA-TRZ and pTPA-TRZ, it was revealed that the attractive interaction between pTPA and TRZ in toluene is weaker than TPA and TRZ. Because of the weaker attractive interaction between pTPA and TRZ in toluene, the dimers adopted numerous ground state conformations resulting in broad emission bands superimposed with multiple small Gaussian peaks. This is in contrast to TPA-TRZ which has only one dominant dimer conformation. This study demonstrates that the strength of intermolecular interactions between donors and acceptors should be taken into consideration in designing supramolecular structures. 相似文献
9.
In this paper, we report an efficient coupling scheme with relaxed misalignment tolerances. The proposed coupling scheme consists of two ball lenses of same diameter (1 mm) and different refractive indices. The second ball lens which is facing the fiber tip has a higher refractive index (1.833), whereas the first one which faces the laser diode has a refractive index of 1.5. Employing Gaussian and ABCD ray tracing optics, the theoretically obtained coupling efficiency can reach a unity with relaxed working distance (separation of the coupling system from the fiber tip) in the range between 1 and 4 mm at some optimum positions of the coupling lenses with regard to each other and to the facet of the laser diode. It has been found that if the distance between the first ball lens and the laser diode (d1) is fixed at 1.1 mm, which is twice its focal length, the coupling efficiency and the working distance as well as the misalignment tolerances are greatly affected by variation of the separation between the two ball lenses (s), and for this proposed coupling scheme the highest coupling efficiency and largest working distance are obtained when s is in the range of 0.3-0.35 mm. Above and below this range there is a significant reduction in the values of the above-mentioned parameters. Experimentally, the Nd:YAG laser welding system has been used for the alignment and welding of the coupling components in a butterfly configuration; the experimentally obtained coupling efficiency of the proposed coupling system was around 75% with relaxed working distance. From the effect of lateral and angular offsets on coupling efficiency, it is clearly noticed that the mode field of laser diode is transformed from elliptical into circular and hence effectively matched with that of the single-mode fiber. 相似文献
10.