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排序方式: 共有123条查询结果,搜索用时 15 毫秒
61.
Tanwar J Datta A Tiwari AK Chaturvedi S Ojha H Allard M Chaudary NK Thirumal M Mishra AK 《Dalton transactions (Cambridge, England : 2003)》2011,40(13):3346-3351
A bis-polyazamacrocycle, 10'-bis(acetamido)ethane-bis[1,4,7-tri(carboxymethane)-1,4,7,10-tetraazacyclododecane] (DO3A-AME-DO3A) was synthesized for application in magnetic resonance imaging. The efficacy of DO3A-AME-DO3A as non ionic magnetic contrast agent was tested by performing relaxometric studies on its gadolinium complex. The longitudinal relaxivity, r(1) and transverse relaxivity, r(2) values were found to be 5.84 mM(-1)s(-1) and 6.82 mM(-1)s(-1), per Gd(III) at pH 7.0, 37 °C. The luminescence properties of europium complex of DO3A-AME-DO3A were investigated in aqueous medium. The lifetime of Eu(2)-DO3A-AME-DO3A in water was found to be 0.786 ms. Emission and luminescence lifetime measurements on the europium complex of DO3A-AME-DO3A gives a hydration number of q = 1.9. The reaction enthalpy and entropy were found to be, ΔH(0) = -(6.2 ± 2) kJ mol(-1), ΔS(0) = - (1.8 ± 0.4) kJ mol(-1)K(-1), and K(Eu)(298) = (1.8 ± 0.1). 相似文献
62.
Kubicki J Zhang Y Vyas S Burdzinski G Luk HL Wang J Xue J Peng HL Pritchina EA Sliwa M Buntinx G Gritsan NP Hadad CM Platz MS 《Journal of the American Chemical Society》2011,133(25):9751-9761
The photochemistry of 2-naphthoyl azide was studied in various solvents by femtosecond time-resolved transient absorption spectroscopy with IR and UV-vis detection. The experimental findings were interpreted with the aid of computational studies. Using polar and nonpolar solvents, the formation and decay of the first singlet excited state (S(1)) was observed by both time-resolved techniques. Three processes are involved in the decay of the S(1) excited state of 2-naphthoyl azide: intersystem crossing, singlet nitrene formation, and isocyanate formation. The lifetime of the S(1) state decreases significantly as the solvent polarity increases. In all solvents studied, isocyanate formation correlates with the decay of the azide S(1) state. Nitrene formation correlates with the decay of the relaxed S(1) state only upon 350 nm excitation (S(0) → S(1) excitation). When S(n) (n ≥ 2) states are populated upon excitation (λ(ex) = 270 nm), most nitrene formation takes place within a few picoseconds through the hot S(1) and higher singlet excited states (S(n)) of 2-naphthoyl azide. The data correlate with the results of electron density difference calculations that predict nitrene formation from the higher-energy singlet excited states, in addition to the S(1) state. For all of these experiments, no recovery of the ground state was observed up to 3 ns after photolysis, which indicates that both internal conversion and fluorescence have very low efficiencies. 相似文献
63.
Ankit Aggarwal Anand Louis Manisha Bansal Naveen Garg Neelima Gupta Shubham Gupta Surabhi Jain 《Mathematical Programming》2013,141(1-2):527-547
We consider the facility location problem where each facility can serve at most U clients. We analyze a local search algorithm for this problem which uses only the operations of add, delete and swap and prove that any locally optimum solution is no more than 3 times the global optimum. This improves on a result of Chudak and Williamson who proved an approximation ratio of ${3+2\sqrt{2}}$ for the same algorithm. We also provide an example which shows that any local search algorithm which uses only these three operations cannot achieve an approximation guarantee better than 3. 相似文献
64.
65.
Rajesh Gupta Sudeep Tanwar Sudhanshu Tyagi Neeraj Kumar 《International Journal of Communication Systems》2019,32(14)
Over the last few years, communication latency has been a major hurdle for most of the applications deployed in different network domains. During this era, a number of communication protocols and standards were developed and used by the community. However, still, the problem of latency persists keeping in view of the quality of service (QoS) and quality of experience (QoE) for different applications. To mitigate the aforementioned issues, in this paper, we present an in‐depth survey of state‐of‐the art proposals having tactile internet as a backbone for delay mitigation using 5G networks for future ultra‐reliable low‐latency applications such as Healthcare 4.0, Industry 4.0, virtual reality and augmented reality, and smart education. From the existing proposals, it has been observed that tactile internet can provide interactions between virtual objects to give a feel of real environment with maximum latency of 1 millisecond. Also, this paper highlights the key differences between the tactile internet and Internet of Things in context with 5G revolution. Then open issues and challenges of tactile internet for smart applications are analyzed. Finally, a comparison of existing proposals with respect to various parameters is presented, which allows the end users to select one of the proposals in comparison with its merits over the others. 相似文献
66.
Mehta Pakhuri Srivastava Shubham Sharma Manish Malik Ruchi 《Structural chemistry》2019,30(4):1159-1172
Structural Chemistry - Competitive AMPA receptor antagonists serve as the promising and validated strategy towards the development of novel antiepileptic agents. For this purpose, the... 相似文献
67.
Srivastava Shubham Vengamthodi Ajeesh Singh Inderpal Choudhary Bhanwar Singh Sharma Manish Malik Ruchi 《Structural chemistry》2019,30(5):1761-1778
Structural Chemistry - The PI3KCA gene functions by activating cascade signaling pathways leading to cell proliferation, survival, and growth. Being one of the frequently aberrant kinase in various... 相似文献
68.
Shubham Garg Heidi Schwartz Mariana Kozlowska Anemar Bruno Kanj Kai Müller Wolfgang Wenzel Uwe Ruschewitz Lars Heinke 《Angewandte Chemie (International ed. in English)》2019,58(4):1193-1197
Conductive metal–organic frameworks (MOFs) as well as smart, stimuli‐responsive MOF materials have attracted considerable attention with respect to advanced applications in energy harvesting and storage as well as in signal processing. Here, the conductance of MOF films of type UiO‐67 with embedded photoswitchable nitro‐substituted spiropyrans was investigated. Under UV irradiation, the spiropyran (SP) reversibly isomerizes to the open merocyanine (MC) form, a zwitterionic molecule with an extended conjugated π‐system. The light‐induced SP–MC isomerization allows for remote control over the conductance of the SP@UiO‐67 MOF film, and the conductance can be increased by one order of magnitude. This research has the potential to contribute to the development of a new generation of photoelectronic devices based on smart hybrid materials. 相似文献
69.
Mst Nasima Khatun Arvin Sain Tanwar Niranjan Meher Parameswar Krishnan Iyer 《化学:亚洲杂志》2019,14(24):4725-4731
The development of a new naphthalene appended naphthalimide derivative ( NMI ) with aggregation‐induced enhanced emission (AIEE) property for the sensitive detection of 4‐nitroaniline (4‐NA) in aqueous media is presented here. The newly designed naphthalimide AIEEgen has an exceptional blue‐shifted condensed state emission that is devoid of any receptor site, accomplished ultrasensitive detection of 4‐NA, which is one of the broad‐spectrum pesticides that belong to the class III toxic chemical, at parts per billion level (LOD/36 ppb, Ksv=4.1×104 m ?1) in water with excellent selectivity even in the presence of potentially competing aliphatic and aromatic amines. The reported probe is the first of its kind, demonstrating major advantages of receptor‐free inner filter effect (IFE) mechanism for the sensitive detection of 4‐NA using an AIEEgenic probe. Excellent sensitivity for 4‐NA is also achieved on paper‐based test‐strip for low‐cost on‐site detection. 相似文献
70.
An electro-optical sensor for microdisplacement measurements based on the triangulation principle has been reported in our earlier publication. The present paper discusses the theory of the error in measurements arising due to the tilt of the object surface and misalignment of illuminating and detecting arms of the system. A method to eliminate the effect of object tilt in measurements is also discussed. 相似文献