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排序方式: 共有1427条查询结果,搜索用时 171 毫秒
41.
Wen-Wen Zi Zihao Gao Prof. Jun Zhang Bao-Xun Zhao Xian-Shu Cai Prof. Hong-Bin Du Prof. Fei-Jian Chen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(10):3976-3979
Extra-large-pore zeolites for processing large molecules have long been sought after by both the academia and industry. However, the synthesis of these materials, particularly extra-large-pore pure silica zeolites, remains a big challenge. Herein we report the synthesis of a new extra-large-pore silica zeolite, designated NUD-6, by using an easily synthesized aromatic organic cation as structure-directing agent. NUD-6 possesses an intersecting 16×8×8-membered ring pore channel system constructed by four-connected (Q4) and unusual three-connected (Q3) silicon species. The organic cations in NUD-6 can be removed in nitric acid to yield a porous material with high surface area and pore volume. The synthesis of NUD-6 presents a feasible means to prepare extra-large pore silica zeolites by using assembled aromatic organic cations as structure-directing agents. 相似文献
42.
Dr. Xiaocui Guo Prof. Feng Li Chunxia Liu Yi Zhu Nannan Xiao Dr. Zi Gu Prof. Dan Luo Prof. Jianhui Jiang Prof. Dayong Yang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(46):20832-20839
The design of controllable dynamic systems is vital for the construction of organelle-like architectures in living cells, but has proven difficult due to the lack of control over defined topological transformation of self-assembled structures. Herein, we report a DNA based dynamic assembly system that achieves lysosomal acidic microenvironment specifically inducing topological transformation from nanoparticles to organelle-like hydrogel architecture in living cells. Designer DNA nanoparticles are constructed from double-stranded DNA with cytosine-rich stick ends (C-monomer) and are internalized into cells through lysosomal pathway. The lysosomal acidic microenvironment can activate the assembly of DNA monomers, inducing transformation from nanoparticles to micro-sized organelle-like hydrogel which could further escape into cytoplasm. We show how the hydrogel regulates cellular behaviors: cytoskeleton is deformed, cell tentacles are significantly shortened, and cell migration is promoted. 相似文献
43.
Highly Enantioselective Kinetic Resolution of Axially Chiral BINAM Derivatives Catalyzed by a Brønsted Acid 下载免费PDF全文
Dr. Dao‐Juan Cheng Liang Yan Prof. Dr. Shi‐Kai Tian Ming‐Yue Wu Lu‐Xin Wang Zi‐Li Fan Dr. Sheng‐Cai Zheng Prof. Dr. Xin‐Yuan Liu Prof. Dr. Bin Tan 《Angewandte Chemie (International ed. in English)》2014,53(14):3684-3687
A highly efficient strategy for the kinetic resolution of axially chiral BINAM derivatives involving a chiral Brønsted acid‐catalyzed imine formation and transfer hydrogenation cascade process was developed. The kinetic resolution provides a convenient route to chiral BINAM derivatives in high yields with excellent enantioselectivities. 相似文献
44.
A silica-based adsorbent, (DtBuCH18C6 + dodecanol)/SiO2-P, which is used for selective separation of Sr(II) from high level liquid wastes, against temperature and gama-irradiation was investigated. The adsorption characteristics of Sr(II), Ba(II), La(III), Nd(III), Gd(III) and Dy(III) under varying nitric acid concentration at different temperatures were measured by batch method. The adsorbent showed higher distribution coefficients (K d) for Sr(II) compared to other tested metal ions, and the K d values of Sr(II) decreased with increasing temperature. Thermodynamic parameters of the adsorption process were calculated. The related parameters in adsorption isotherm models were obtained using a non-linear fitting. Uptake capacity from 0.38 to 0.43 mmol g?1 was obtained for Sr(II) in the temperature range of 298–323 K by the Langmuir equation fitting. The leakage of total organic carbon was below 120 ppm at 298 K and 180 ppm at 323 K, respectively. The degradation of the adsorbent irradiated in 2 M HNO3 was investigated. It is found that the adsorbed dose of γ-ray more than 50 KGy has a strong influence on K d of Sr(II). The K d values of Sr(II) decrease about 3 times ranged from 50 to 500 KGy. 相似文献
45.
Zhi Ping Xu Zi Gu Xiaoxi Cheng Firas Rasoul Andrew K. Whittaker Gao Qing Max Lu 《Journal of nanoparticle research》2011,13(3):1253-1264
A novel nanocomposite film for sustained release of anionic ophthalmic drugs through a double-control process has been examined
in this study. The film, made as a drug-loaded contact lens, consists principally of a polymer hydrogel of 2-hydroxyethyl
methacrylate (HEMA), in whose matrix MgAl-layered double hydroxide (MgAl-LDH) nanoparticles intercalated with the anionic
drug are well dispersed. Such nanocomposite films (hydrogel-LDH-drug) contained 0.6–0.8 mg of MgAl-LDH and 0.08–0.09 mg of
the ophthalmic drug (ketorolac) in 1.0 g of hydrogel. MgAl-drug-LDH nanoparticles were prepared with the hydrodynamic particle
size of 40–200 nm. TEM images show that these nanoparticles are evenly dispersed in the hydrogel matrix. In vitro release
tests of hydrogel-LDH-drug in pH 7.4 PBS solution at 32 °C indicate a sustained release profile of the loaded drug for 1 week.
The drug release undergoes a rapid initial burst and then a monotonically decreasing rate up to 168 h. The initial burst release
is determined by the film thickness and the polymerization conditions, but the following release rate is very similar, with
the effective diffusion coefficient being nearly constant (3.0 × 10−12 m2/s). The drug release from the films is mechanistically attributed to anionic exchange and the subsequent diffusion in the
hydrogel matrix. 相似文献
46.
Design of square-shaped heat flux cloaks and concentrators using method of coordinate transformation
A square-shaped heat flux cloak and a square-shaped heat flux concentrator have been designed theoretically according to the invariance symmetry of steady state thermal conductive equation. The direction of heat flux in these devices can be modulated as desired. Using the method of coordinate transformation, the inhomogeneous and anisotropic thermal conductivity in the transformation region have been acquired. Two-dimensional finite element simulations were performed to confirm the theoretical results. 相似文献
47.
In this paper, an equivalent relation among the reflexivity, weak sequential completeness and bounded completeness in full function space is given. Some results on weakly sequential compactness of subset and the property (u) in substitution spaces are obtained. 相似文献
48.
Van T. Tran Zi‐Qi Li Omar Apolinar Joseph Derosa Matthew V. Joannou Steven R. Wisniewski Martin D. Eastgate Keary M. Engle 《Angewandte Chemie (International ed. in English)》2020,59(19):7409-7413
We report that Ni(COD)(DQ) (COD=1,5‐cyclooctadiene, DQ=duroquinone), an air‐stable 18‐electron complex originally described by Schrauzer in 1962, is a competent precatalyst for a variety of nickel‐catalyzed synthetic methods from the literature. Due to its apparent stability, use of Ni(COD)(DQ) as a precatalyst allows reactions to be conveniently performed without use of an inert‐atmosphere glovebox, as demonstrated across several case studies. 相似文献
49.
Pan Li Shijun Xu Chunyang Yu Zi‐Ying Li Jianping Xu Zi‐Mu Li Lingyi Zou Xuebing Leng Shan Gao Zhiqiang Liu Xiaoyun Liu Shaodong Zhang 《Angewandte Chemie (International ed. in English)》2020,59(18):7113-7121
Considerable efforts have been made to increase the topological complexity of mechanically interlocked molecules over the years. Three‐dimensional catenated structures composed of two or several (usually symmetrical) cages are one representative example. However, owing to the lack of an efficient universal synthetic strategy, interlocked structures made up of dissymmetric cages are relatively rare. Since the space volume of the inner cavity of an interlocked structure is smaller than that outside it, we developed a novel synthetic approach with the voluminous reductant NaBH(OAc)3 that discriminates this space difference, and therefore selectively reduces the outer surface of a catenated dimer composed of two symmetric cages, thus yielding the corresponding catenane with dissymmetric cages. Insight into the template effect that facilitates the catenation of cages was provided by computational and experimental techniques. 相似文献
50.
Xiang Chen Yun‐Ke Bai Chen‐Zi Zhao Xin Shen Qiang Zhang 《Angewandte Chemie (International ed. in English)》2020,59(28):11192-11195
Lithium bonds are analogous to hydrogen bonds and are therefore expected to exhibit similar characteristics and functions. Additionally, the metallic nature and large atomic radius of Li bestow the Li bond with special features. As one of the most important applications of the element, Li batteries afford emerging opportunities for the exploration of Li bond chemistry. Herein, the historical development and concept of the Li bond are reviewed, in addition to the application of Li bonds in Li batteries. In this way, a comprehensive understanding of the Li bond in Li batteries and an outlook on its future developments is presented. 相似文献