全文获取类型
收费全文 | 150篇 |
免费 | 18篇 |
国内免费 | 2篇 |
专业分类
化学 | 114篇 |
晶体学 | 2篇 |
力学 | 10篇 |
数学 | 24篇 |
物理学 | 20篇 |
出版年
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2017年 | 7篇 |
2016年 | 12篇 |
2015年 | 9篇 |
2014年 | 10篇 |
2013年 | 24篇 |
2012年 | 22篇 |
2011年 | 13篇 |
2010年 | 8篇 |
2009年 | 14篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1988年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1979年 | 3篇 |
排序方式: 共有170条查询结果,搜索用时 15 毫秒
131.
132.
A Controlled Route to a Luminescent 3 d10–5 d10 Sulfido Cluster Containing Unique AuCu2(μ3‐S) Motifs
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Alexander M. Polgar Dr. Chhatra B. Khadka Dr. Mahmood Azizpoor Fard Brian Nikkel Terrence O'Donnell Tobias Neumann Kiana Lahring Kyle Thompson Carolyn Cadogan Dr. Florian Weigend Prof. Dr. John F. Corrigan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(51):18378-18382
The first examples of gold(I) trimethylsilylchalcogenolate complexes were synthesized and their reactivity showcased in the preparation of a novel gold–copper–sulfur cluster [Au4Cu4S4(dppm)2] (dppm=bis(diphenylphosphino)methane). The unprecedented structural chemistry of this compound gives rise to interesting optoelectronic properties, including long‐lived orange luminescence in the solid state. Through time‐dependent density functional theory calculations, this emission is shown to originate from ligand‐to‐metal charge transfer facilitated by Au???Cu metallophilic bonding. 相似文献
133.
Sara Tavakkoli Fard Dr. Kohei Sekine Dr. Kaveh Farshadfar Dr. Frank Rominger Dr. Matthias Rudolph Dr. Alireza Ariafard Prof. Dr. A. Stephen K. Hashmi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(10):3552-3559
A simple gold-catalyzed annulation of 1,8-dialkynylnaphthalenes utilizing a cationic gold catalyst was developed. Such a peri-position of two alkynyl substituents has not been studied in gold catalysis before. Dependent on the substrate, the reactions either follow a mechanism involving vinyl cation intermediates or involve a dual gold catalysis mechanism which in an initial 6-endo-dig-cyclization generates gold(I) vinylidene intermediates that are able to insert into C−H bonds. Indenophenalene derivatives were obtained in moderate to high yields. In addition, the bidirectional gold-catalyzed annulation of tetraynes provided even larger conjugated π-systems. The optoelectronic properties of the products were also investigated. 相似文献
134.
Narges Malmir Najaf Allahyari Fard Yamkela Mgwatyu Lukhanyo Mekuto 《Molecules (Basel, Switzerland)》2021,26(6)
Cyanide is a hazardous and detrimental chemical that causes the inactivation of the respiration system through the inactivation of cytochrome c oxidase. Because of the limitation in the number of cyanide-degrading enzymes, there is a great demand to design and introduce new enzymes with better functionality. This study developed an integrated method of protein-homology-modelling and ligand-docking protein-design approaches that reconstructs a better active site from cyanide hydratase (CHT) structure. Designing a mutant CHT (mCHT) can improve the CHT performance. A computational design procedure that focuses on mutation for constructing a new model of cyanide hydratase with better activity was used. In fact, this study predicted the three-dimensional (3D) structure of CHT for subsequent analysis. Inducing mutation on CHT of Trichoderma harzianum was performed and molecular docking was used to compare protein interaction with cyanide as a ligand in both CHT and mCHT. By combining multiple designed mutations, a significant improvement in docking for CHT was obtained. The results demonstrate computational capabilities for enhancing and accelerating enzyme activity. The result of sequence alignment and homology modeling show that catalytic triad (Cys-Glu-Lys) was conserved in CHT of Trichoderma harzianum. By inducing mutation in CHT structure, MolDock score enhanced from −18.1752 to −23.8575, thus the nucleophilic attack can occur rapidly by adding Cys in the catalytic cavity and the total charge of protein in pH 6.5 is increased from −6.0004 to −5.0004. Also, molecular dynamic simulation shows a stable protein-ligand complex model. These changes would help in the cyanide degradation process by mCHT. 相似文献
135.
Manouchehr Zaker 《Journal of Graph Theory》2008,58(2):110-122
In this article we first give an upper bound for the chromatic number of a graph in terms of its degrees. This bound generalizes and modifies the bound given in 11 . Next, we obtain an upper bound of the order of magnitude for the coloring number of a graph with small K2,t (as subgraph), where n is the order of the graph. Finally, we give some bounds for chromatic number in terms of girth and book size. These bounds improve the best known bound, in terms of order and girth, for the chromatic number of a graph when its girth is an even integer. © 2008 Wiley Periodicals, Inc. J Graph Theory 58:110–122, 2008 相似文献
136.
Mehran Javanbakht Solmaz Eynollahi Fard Majid Abdouss Ali Mohammadi Mohammad Reza Ganjali Parviz Norouzi Leila Safaraliee 《Electroanalysis》2008,20(18):2023-2030
Despite the increasing number of applications of molecularly imprinted polymers (MIPs) in analytical chemistry, the construction of a biomimetic potentiometric sensor remains still challenging. In this work, a biomimetic potentiometric sensor, based on a non‐covalent imprinted polymer was fabricated for the recognition and determination of cetirizine. The MIP was synthesized by precipitation polymerization, using cetirizine dihydrochloride as a template molecule, methacrylic acid (MAA) as a functional monomer and ethylene glycol dimethacrylate (EGDMA) as a cross linking agent. The sensor showed high selectivity and a sensitive response to the template in aqueous system. The MIP‐modified electrode exhibited Nernstian response (28.0±0.9 mV/decade) in a wide concentration range of 1.0×10?6 to 1.0×10?2 M with a lower detection limit of 7.0×10?7 M. The electrode has response time of ca. 20 s, high performance, high sensitivity, and good long term stability (more than 5 months). The method was satisfactory and used to the cetirizine assay in tablets and biological fluids. 相似文献
137.
In this paper, a novel dispersion-shifted multi-clad optical fiber with very small bending loss and ultra-high bit-rate applicable for large capacity information transmission systems is presented. To decrease dispersion and higher-order dispersion effects at λ = 1.55 μm, a weighted pulse broadening factor and genetic algorithm (GA) optimization technique is used. Compared to the works reported previously, this method can precisely set the zero-dispersion wavelength. This kind of dispersion-shifted fibers has dispersion, dispersion slope, mode field diameter (MFD), effective area and quality factor within −1.40 × 10−4 to −8.44 × 10−2 ps/km nm, 3.06 × 10−2 to −4.07 × 10−2 ps/km nm2, 5.56−5.85 μm, 119.25−176.42 μm2 and 3.49-5.27 at λ = 1.55 μm, respectively. Besides, by applying dispersion at λ = 1.55 μm as the cost function, dispersion of about 1.31 × 10−8 ps/km nm is obtained. Thus, this novel optical fiber can be used in long-haul high information-transmission capacity communication systems. 相似文献
138.
139.
Fekra Somayeh Saleh Fard Narges Elmi Fazaeli Reza 《Russian Journal of Applied Chemistry》2021,94(6):824-834
Russian Journal of Applied Chemistry - This study evaluated a removal efficiency of NLFX from aqueous solutions using a photocatalytic process. In this study, Bi2WO6 were synthesized by microwave... 相似文献
140.
Mehran Javanbakht Leila Safaraliee Mohammad Reza Ganjali Majid Abdouss Parviz Norouzi Farnoush Faridbod Solmaz Eynollahi Fard 《中国化学会会志》2009,56(2):296-302
Ion‐selective electrodes play an important role in pharmaceutical analysis due to their simplicity, rapidity and accuracy over some other analytical methods. This research introduces the design of an ion‐pair of imipramine‐tetraphenyl borate (IMP‐TPB) based PVC membrane sensor for IMP hydrochloride determination. Effect of the membrane composition, the pH influence and the effect of lipophilic anionic additives on the response characteristics of the electrode were investigated. After a series of experiments, the best electrode performance was accomplished with a membrane composition of 30% PVC, 63% DBP, 5% (IMP‐TPB) and 2% (NaTPB). This electrode illustrated a fast (15 s), stable and Nernstian response across a relatively wide IMP hydrochloride concentration range (10?5 to 10?5 M), in the pH range of (3.0–8.0), and it can be used for at least two months without any measurable change in sensitivity. Additionally, the interference between IMP and several drugs and common inorganic anions was negligible as shown by the potentiometric selectivity coefficient data. The membrane sensor was successfully applied to the determination of IMP in tablets and human urine samples, and very good recovery results were obtained. 相似文献