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排序方式: 共有843条查询结果,搜索用时 15 毫秒
41.
Hao Chen Xi Li Minfeng Huo Liying Wang Yu Chen Wei Chen Bailiang Wang 《Nano Research》2021,14(1):205-211
Exploring alternative biomedical use of traditional drugs in different disease models is highly important as it can reduce the cost of drug development and overcome several critical issues of traditional chemodrugs such as low chemotherapeutic efficiency,severe side effect,and drug resistance.Disulfiram(DSF),a clinically approved alcohol-aversion drug,was recently demonstrated tofeature tumor-growth suppression effect along with the co-administration of Cu2+species,but direct Cu2+administration mode might cause severe toxicity originating from low Cu2+accumulation into the tumor and nonspecific Cu2+distribution-induced cytotoxicity.Based on the intriguing drug-delivery performance of nanoscale metal-organic frameworks(MOFs),we herein construct HKUST nMOFs as the Cu2+self-supplying nanocarriers for efficient delivery of the D SF drug.The mildly acidic condition of tumor microenvironment initially triggered the release of Cu ions from HKUST nMOFs,which further reacted with the encapsulated DSF toform toxic Cu(DDTC)2(activation)for tumor chemotherapy.Especially,during the Cu(DDTC)2 complexation,Cu+species were formed concomitantly,triggering the intratumoral nanocatalytic therapy for the generation of reactive oxygen species to synergistically destroying the tumor cells/tissue.As a result,synergetic tumor-responsive chemotherapy and nanocatalytic therapy are enabled by DSF@HKU ST nanodrugs,as demonstrated by the dominant anticancer efficacy with satisfied biocompatibility both in vitro and in vivo.The present work offers a sophisticated strategy for tumor-responsive nontoxic-to-toxic therapeutic with high biocompatibility. 相似文献
42.
Numerical Simulation of Microgravity Flame Spread Over Solid CombustiblesNumericalSimulationofMicrogravityFlameSpreadOverSoli... 相似文献
43.
Carbonates have been known to act as hydrocarbon source rocks, but their basic geochemical and associated hydrocarbon generation characteristics remain not well understood as they occur with argillaceous source rocks in most cases, and the hydrocarbon generation from each rock type is di cult to distinguish, forming one of puzzling issues within the field of petroleum geology and geochemistry. To improve the understanding of this critical issue, this paper reviews recent advances in this field and provides a summary of key areas that can be studied in future. Results show that carbonate source rocks are generally associated with high-salinity environments with low amounts of terrestrial inputs and low dissolved oxygen contents. Petrographically, these source rocks are dark gray or black, fine-grained, stratified, and contain bacterial and algal bioprecursors along with some other impurities. They generally have low organic matter contents, although these can vary significantly in di erent cases(e.g., the total organic carbon contents of marine and lacustrine carbonate source rocks in China are generally 0.1%–1.0% and 0.4%–4.0%, respectively). These rocks contain type I and type II kerogen, meaning there is a lack of vitrinites. This means that assessment of the maturity of the organic matter in these sediments needs to use non-traditional techniques rather than vitrinite reflectance. In terms of molecular geochemistry, carbonate source rocks have typical characteristics indicative of generally reducing and saline environments and lower organism-dominated bioprecursors of organic matter, e.g., high contents of sulfur compounds, low Pr/Ph ratios, and dominance of n-alkanes. Most of the carbonate source rocks are typically dominated by D-type organic facies in an oxidized shallow water mass, although high-quality source rocks generally contain A-and B-type organic facies in saline lacustrine and marine-reducing environments, respectively. The hydrocarbon generation model for the carbonate source rocks can involve early, middle, and late stages, with a diversity of hydrocarbons within these rocks, which can be aggregated, adsorbed, enclosed within minerals, or present as inclusions. This in turn implies that the large-scale hydrocarbon expulsion from these rocks is reliant on brittle deformation caused by external forces. Finally, a number of aspects of these source rocks remain unclear and need further study, including the e ectiveness of carbonates as hydrocarbon source rocks, bioprecursors, and hydrocarbon generation models of carbonate source rock, and the di erences between marine and lacustrine carbonate source rocks. 相似文献
44.
Conventional pulsed-field gel electrophoresis (PFGE) protocols, used extensively as a successful approach for subtyping many salmonellae, may be inadequate for discriminating strains sharing levels of homogeneity within the same serotype. Four additional restriction enzymes (SpeI, PacI, SfiI, and NotI), in addition to XbaI and BlnI, were used in PFGE typing of 33 Salmonella Heidelberg, 27 Salmonella Kentucky, 27 Salmonella SaintPaul, and 27 Salmonella Hadar isolates that were recovered from poultry and porcine retail meats from different states of the United States. A dendrogram derived from the combined analysis of six enzymes was highly discriminatory with a Simpson index of diversity value of over 0.950. The ratio of nodes to isolates was more than 0.75 with an average of fewer than three isolates in each polytomy for all four serotypes. Two three-enzyme combinations, SpeI/NotI/SfiI for Salmonella Heidelberg and Salmonella Hadar, and SpeI/BlnI/SfiI for Salmonella Kentucky and Salmonella SaintPaul, were found to have comparable discriminatory abilities of differentiating isolates of these Salmonella serotypes with the six-enzyme combination. The enhanced discriminatory PFGE-based subtyping scheme can be used effectively for the differentiation of strains of the four Salmonella serotypes. The findings also highlight PFGE analysis as a continued essential and informative subtyping method for source tracking and outbreak investigations of these and other Salmonella pathogens. 相似文献
45.
Xin ZHANG Tao HUANG Bo WU Youmin HU Shuai HUANG Quan ZHOU Xi ZHANG 《Frontiers of Mechanical Engineering》2021,16(2):340-352
Frontiers of Mechanical Engineering - Deep learning has achieved much success in mechanical intelligent fault diagnosis in recent years. However, many deep learning methods cannot fully extract... 相似文献
46.
Pei Qingqi Li Hongning Pang Liaojun Hao Yin Hong Tang Key Lab of Computer Networks Information Security of Ministry of Education Xidian University Xi’an China Institute of China Electronic System Engineering Corporation Beijing China 《中国通信》2010,7(1):73-79
Wireless sensor networks are open architectures, so any potential threat can easily intercept, wiretap and counterfeit the information. Therefore, the safety of WSN is very important. Since any single key system cannot guarantee the security of the wireless sensor network for communications, this paper introduces a hierarchical key management scheme based on the different abilities of different sensor nodes in the clustered wireless sensor network. In this scheme, the nodes are distributed into several clusters, and a cluster head must be elected for each cluster. Private communication between cluster heads is realized through the encryption system based on the identity of each head while private communication between cluster nodes in a same cluster head is achieved through the random key preliminary distribution system. Considering the characteristics of WSN, we adopt dynamic means called dynamic cluster key management scheme to deal with master key, so master key will be updated according to the changed dynamic network topology. For cluster head node plays a pivotal role in this scheme, a trust manage-ment system should be introduced into the election of the cluster head which will exclude the malicious node from outside the cluster, thus improve the whole network security. 相似文献
47.
Xiaoping Su Pu An Junwen Gao Rucheng Wang Yujuan Zhang Xi Li Yangkun Zhao Yongqi Liu Xiaoxun Ma Ming Sun 《中国化学工程学报》1982,28(10):2566-2576
The selective catalytic hydrogenation of naphthalene to high-value tetralin was systematically investigated. A series of Al2O3 catalysts containing different active metals (Co, Mo, Ni, W) were prepared by incipient wetness impregnation. The effects of different active metals forms (oxidation, reduction, sulfuration) and reaction conditions on naphthalene hydrogenation were investigated and the catalysts were characterized by XRD, XPS, BET, NH3- TPD and SEM. Especially, Ni-Mo/Al2O3 was first used in this reactive system. The results show that the oxidative 4%NiO-20%MoO3/Al2O3 is the best catalyst for the preparation of tetralin. The conversion of naphthalene and the selectivity of tetralin can reach 95.62% and 99.75% respectively at 200 ℃, 8 h and 6 MPa. Compared with reduced and sulfureted 4%NiO-20%MoO3/Al2O3 catalysts, oxidative 4%NiO-20%MoO3/Al2O3 has a well dispersed and uniform monolayer of the active metals, larger pore volume and size, and larger total acidity. NiO-MoO3/Al2O3 has a synergistic effect between NiO activity and MoO3 selectivity. 相似文献
48.
Yuan Xi 《中国有色金属学会会刊》1995,(4)
ASOLUTIONOFSHAPEEXTRUSIONORDRAWINGBASEDONDEFORMATIONTHEORYYuanXi(DepartmentofMaterialsScienceandEngineering,CentralSouthUnive... 相似文献
49.
The symmetrical superlattice intrinsic stacking faults(SISFs)formed on {111} planes are thepredominant crystal defects in polycrystalline Ni_3AI after slight deformation at room temper-ature.The formation of this kind of SISF is resulted from the dipoles which are distributed onthe neighboring {111} planes after reorientation,dissociation and annihilation under appliedstress. 相似文献
50.
1 Introduction Raster to Vector Conversion (RVC) for Engineering Drawings(ED), also known as vectorization, is a procedure to find the vector form of graphic primitives – straight line, circle and arc segments – from the raster engineering drawing. It is an automated process of analyzing and recognizing graphic primitives in the raster engineering drawing, converting them into vector form. A lot of instances need to accomplish the raster to vector recognition and conversion, for example,… 相似文献