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971.
目的 以肌理设计中蕴含的韵律为研究对象,通过参数化的设计方法,将肌理设计中的韵律构成由定性的表现转化为定量的设计,借助计算机强大的运算能力可以有效提升肌理设计的智能化、系统性与适应性。方法 通过系统分析肌理设计的韵律法则,建立基于肌理韵律的数学函数模型,并将其作为肌理参数化设计的基本参数输入参数化设计系统进行编码识别,在此基础上构建参数化设计框架,实现基于韵律法则的肌理参数化设计。结论 在参数化设计框架基础上构建肌理参数化设计平台,借助可自定义的肌理韵律的函数模型,可以丰富肌理韵律的参数化生成形式,为肌理韵律的设计提供科学的方法指导。参数化的实时交互技术可以快速生成大量肌理设计方案,有助于提高设计效率,方便生成优化的肌理设计方案。 相似文献
972.
可压缩成像是一种新兴的基于压缩感知理论的新成像技术,其核心思想是如果空间场景是稀疏或可压缩,那么它可以用远少于经典的Nyquist采样数目的测量值捕获的足够信息重构原场景;构建合适的测量矩阵并易于使用物理实现压缩感知理论中对于图像的随机线性测量是可压缩成像理论实用化的关键之一。该文在研究Bernoulli和Circulant矩阵的基础上,提出一种新的随机间距稀疏三元循环相位掩膜矩阵。模拟实验结果表明,在可压缩双透镜成像系统单次曝光下,与Bernoulli和Bernoulli-Circulant相位掩膜矩阵相比,新相位掩膜矩阵的成像信噪比与之相当;但是该文提出的矩阵随机独立变元个数和非零元个数显著减少,易于数据存储与传输;更重要的是物理上更容易实现,重构时间是只有原来的约20%~50%。新的相位掩膜矩阵的研究对于可压缩成像理论的实际应用具有重要的意义。 相似文献
973.
最大熵模型以其能够较好地包容各种约束信息及与自然语言模型相适应等优点在词性标注研究中取得了良好的效果.因此,将其作为基本框架,提出了一种融合语言特征的最大熵蒙古文词性标注模型.首先,根据蒙古文构词特点及统计分析结果,定义并选取特征模板,利用训练语料提取了大量的候选特征集合,针对错误或者无效的特征通过设置一些规则筛选特征.然后,训练最大熵概率模型参数.实验结果表明,融合蒙古文形态特征的最大熵模型可以较好地标注蒙古文. 相似文献
974.
为研究0.001 cc微小封闭空间内部气氛瞬态检测过程中的气体压力变化与质量歧视现象,本文使用直接模拟蒙特卡罗方法结合简化伯努利碰撞对选择格式,针对由取样腔、毛细管、进样通道、离化室与质谱仪组成的典型检测系统,对不同分压比下的氮气与氢气二元混合气体瞬态检测过程进行了研究。结果显示研究中取样腔压力的降低对于毛细管流导的影响可忽略,但毛细管对于混合气体中各组分流导会随质量较轻气体的占比增加而增加。离化室中气体压力在快速上升至最大值后在模拟时间内近似指数下降,同时气体分压比在检测过程中存在剧烈变化,为准确获取样品内气体分压比带来挑战。文章提出了利用混合气体流导值与离化室压力下降曲线对气体质量歧视现象进行修正的方法,气体分压修正偏差小于6%,分压比修正偏差小于1%。研究结果为微气量瞬态检测分析与气体质量歧视的修正提供了理论参考。 相似文献
975.
976.
Long Zhang Yining Zhang Xu Wang Yi Zhou Ji Qi Linbo Gu Qiu Zhao Rutong Yu Xiuping Zhou 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(44):2301439
Although the chemo- and immuno-therapies have obtained good responses for several solid tumors, including those with brain metastasis, their clinical efficacy in glioblastoma (GBM) is disappointing. The lack of safe and effective delivery systems across the blood-brain barrier (BBB) and the immunosuppressive tumor microenvironment (TME) are two main hurdles for GBM therapy. Herein, a Trojan-horse-like nanoparticle system is designed, which encapsulates biocompatible PLGA-coated temozolomide (TMZ) and IL-15 nanoparticles (NPs) with cRGD-decorated NK cell membrane (R-NKm@NP), to elicit the immunostimulatory TME for GBM chemo-immunotherapy. Taking advantage of the outer NK cell membrane cooperating with cRGD, the R-NKm@NPs effectively traversed across the BBB and targeted GBM. In addition, the R-NKm@NPs exhibited good antitumor ability and prolonged the median survival of GBM-bearing mice. Notably, after R-NKm@NPs treatment, the locally released TMZ and IL-15 synergistically stimulated the proliferation and activation of NK cells, leading to the maturation of dendritic cells and infiltration of CD8+ cytotoxic T cells, eliciting an immunostimulatory TME. Lastly, the R-NKm@NPs not only effectively prolonged the metabolic cycling time of the drugs in vivo, but also has no noticeable side effects. This study may offer valuable insights for developing biomimetic nanoparticles to potentiate GBM chemo- and immuno-therapies in the future. 相似文献
977.
Weidong Wen Ping Yan Wanping Sun Yitong Zhou Xin-Yao Yu 《Advanced functional materials》2023,33(6):2212236
Electrocatalytic nitrate (NO3−) reduction reaction (NITRR) is an inspiring route for ammonia (NH3) synthesis at ambient condition. The metallic Cu-based material with low cost and high activity is one of the most promising electrocatalysts for NITRR. However, due to the weaker atomic H*-providing capacity, the produced intermediate—nitrite tends to accumulate on its surface, leading to unsatisfactory NH3 selectivity and Faradic efficiency (FE). Herein, a novel and facile O2/Ar plasma oxidation and subsequent electro-reduction strategy is developed to synthesize a kind of metastable phase Cu. Excitingly, the metastable phase Cu demonstrates superior NITRR performance to conventional phase Cu with high NH4+ selectivity (97.8%) and FE (99.8%). Density function theory (DFT) calculations reveal that the upshift of the d-band center to near the Fermi level in metastable phase Cu contributes to the enhanced activity, while the relatively strong adsorption of H* facilitates the conversion from NO2*/NO* to NOOH*/NOH* and thus ensures high selectivity and FE. Furthermore, when evaluated as cathode material in Zn-NO3− battery, high power density (7.56 mW cm−2) and NH4+ yield (76 µmol h−1 cm−2) are achieved by the metastable phase Cu-based battery. 相似文献
978.
979.
Yongchao Wang Prof. Shan Tang 《Chembiochem : a European journal of chemical biology》2023,24(10):e202300036
Covalent catalytic intermediates provide valuable information for revealing the catalytic mechanism, probing the enzyme activity and identifying substrate specificity. However, naturally formed covalent intermediates are too rapidly degraded for general biological studies. In order to capture transient covalent intermediates, a variety of chemical strategies have been developed over decades to extend the half-life of the enzyme-substrate intermediates (or close analogues) required for the downstream structural and functional studies. This review summarizes three general mechanism-based strategies for trapping covalent catalytic intermediates. In particular, enzyme mutant-based approaches, especially the introduction of genetically encoded 2,3-diaminopropionic acid to replace the catalytic cysteine/serine in proteases for acyl-enzyme intermediate trapping are described. In addition, the applications of trapped intermediates in structural, functional and protein labeling studies are presented, and the potential new directions of using enzyme substrate traps are discussed at the end of the review. 相似文献
980.
Xinfeng Tang Yanhua Zhu Delong Duan Xingwu Zhai Yujian Xia Tao Xu Qian Liu Hui Zhang Min Zhou 《Advanced functional materials》2023,33(42):2305965
Due to the deep biological penetrability and therapeutic depth, the photothermal therapy over second near-infrared region (NIR-II) is booming against deep-seated tumors. Intensive endeavors are committed to looking for suitable photothermal agents (PTAs), but the progress seems not so satisfied toward the choice of PTA dosage. Herein, a comprehensive parameter, incident photon-to-thermal conversion coefficient (IPTCE), is used to evaluate the overall conversion of PTAs at different dosage, which will benefit for determining the optimized dosage of PTAs in pursuit of complete healing together with reduced long-term damages of nanodrugs. To prove the possibility, a series of anionic solid solution MXenes are chosen as hosts due to their versatile chemical compositions and correspondingly tunable light response. By deconvoluting fundamental structure–composition–property relationships, anionic regulation with extra electron injection leads to tunable free carrier densities and enhanced NIR-II harvesting. Ti3C1.23N0.77 with high-level nitrogen exhibits extraordinary extinction coefficient (43.5 L g−1 cm−1) than other MXenes. The parameter of IPTCE can guide the choice of PTA concentration for complete photothermal healing in vitro and vivo. This proof-of-principle demonstration highlights synthetically tailoring of the light harvesting over NIR-II biowindow for a given host material by anionic regulation and further optimizes tumor photothermal therapy at low dose. 相似文献