共查询到20条相似文献,搜索用时 93 毫秒
1.
2.
步氏巨猿(Gigantopithecus blacki)是更新世时期生活于我国华南地区的一种超大型猿类, 它的体态特征和演化分类倍受关注。牙齿釉质厚度在探讨灵长类食性、环境适应以及系统演化方面具有重要意义。本文利用显微CT技术构建18颗巨猿臼齿虚拟模型, 测量其釉质厚度。将巨猿釉质厚度与现代人、现生类人猿、古人类、中新世古猿及其他现生灵长类进行比较, 从牙齿釉质厚度探讨巨猿的食性适应和系统演化问题。结果发现巨猿的实测釉质厚度是目前所有已知现生和化石灵长类中最厚的, 只有傍人、南非早期人属及奥兰诺古猿三种化石灵长类与之接近; 如果考虑不同物种牙齿与身体大小的关联因素, 相对釉质厚度指数显示巨猿属于"厚"釉质类型, 但非"超厚"类型, 低于奥兰诺古猿、傍人、南非早期人属; 巨猿与某些中新世古猿 (如原康修尔猿尼安萨种、非洲古猿)、南方古猿、东非早期人属、亚洲直立人以及现代人、现生卷尾猴的相对釉质厚度指数相近。巨猿的厚釉质特征与其食性和环境适应密切相关, 使得牙齿具有非常强的抗磨损功能, 能够适应长时间的咀嚼和研磨食物。从釉质厚度的系统演化角度推测, 厚釉质应该是人类祖先的特征性状, 巨猿有可能是早期人类支系演化过程中的一个特化旁支, 同时也不排除巨猿是从某种具有厚釉质的中新世古猿旁支平行演化而来的可能性。 相似文献
3.
目的 细胞温度成像可以帮助科学家研究和理解细胞内部的温度分布,揭示细胞代谢和生物化学过程的关键信息。目前,基于荧光温度探针的细胞温度成像技术存在低温度分辨率和有限测量范围等限制。本文旨在利用单分子量子相干过程依赖温度的特性,开发一种单细胞温度成像和实时检测技术。方法 基于飞秒脉冲激光制备延时和相位可调的飞秒脉冲对,调制的脉冲对通过显微系统激发细胞内标记的荧光单分子,之后收集并记录每个荧光光子的到达时间。利用单分子相干过程与周围环境温度的关系,定义单分子量子相干可视度(V),建立V与环境温度的对应关系。通过调制解调荧光光子的到达时间,获取单分子周围环境温度,结合扫描成像,实现细胞的温度成像和实时检测。结果 该方法可以实现高精度(温度分辨率<0.1℃)和大范围温度(10~50℃)的温度成像和测量,并观测到了单个细胞代谢相关的温度变化。结论 该研究有助于深入了解细胞代谢、蛋白质功能和疾病机制,为生物医学研究提供重要工具。 相似文献
4.
细胞作为生命体基本的结构和功能单元,在生物、医学等领域有着非常重要的研究意义。随着现代科学和技术的发展,科学家们借助电镜对细胞以及细胞器的空间结构已经有非常清晰的认识,但是对它们的功能以及细胞之间的相互作用却了解得非常少,而这恰恰又是疾病治疗和药物开发亟需了解的信息,因此对离体活细胞(简称活细胞)和活体生物组织细胞(简称活体细胞)中亚细胞器的研究变得非常重要。然而细胞中许多细胞器的结构在纳米量级,传统的光学成像技术由于受到光学衍射极限的限制是无法观察到纳米量级的生物结构,因此光学超分辨成像技术是目前研究亚细胞器结构和功能的有效工具。在所有光学超分辨显微技术中,受激发射损耗显微术(stimulated emission depletionmicroscopy,STED)由于具有实时成像、三维超分辨和断层成像的能力,非常适合用于纳米尺度的活细胞和活体细胞成像研究,而且STED超分辨成像技术经过近几十年的发展,已经广泛用于活细胞甚至活体小鼠细胞的超分辨动态观测。本文总结了近年来活细胞和活体小鼠神经元细胞等领域STED超分辨成像的研究进展,介绍了用于活细胞和活体细胞STED超分辨成像的荧光染料... 相似文献
5.
城市人口和产业的聚集伴随化石能源消费的迅速增长,导致空气污染物排放量不断增加,对区域气候产生了不可逆的负面影响。以多源遥感数据为基础,对京津冀大气污染传输通道城市群(“2+26”城市群)2015—2019年气溶胶光学厚度(AOD)、PM2.5浓度的时空分布格局进行分析,从月份、季节、年份三个时间维度定量分析其时空变化规律,并通过计算相关性系数来分析气溶胶光学厚度对PM2.5浓度的影响。主要得出研究结论如下:(1)PM2.5浓度整体呈现冬季>春季>秋季>夏季的趋势,并且表现出高度空间自相关性,2015—2019年间,PM2.5浓度显著下降至40μg/m3以下;(2)AOD平均范围值在0—1之间,总体上呈现春夏季高,秋冬季低的分布特点,到2019年,春夏秋三季AOD浓度呈现明显降低,夏季下降趋势最为显著,AOD同样表现出高度空间自相关性;(3)AOD与PM2.5浓度存在显著的正相关关系。从季节变化上看,相关性呈现出:秋季>夏季>冬... 相似文献
6.
7.
3-(4,5-二甲基-2-噻唑)-2,5-二苯基溴化四唑盐)(MTT)比色法是传统上检测细胞增殖和细胞毒性的常用方法.
CloneSelectTM成像系统是一种以影像为基础的用于分析细胞生长的可视检测系统.本研究采用人结直肠癌HCT116细胞系,运用CloneSelect成像系统和MTT方法分别检测药物阿的平的细胞毒性,并采用Bland Altman作图法比较两种实验方法获得的pEC50值,分析两种研究方法获得的结果的一致性. 结果表明,CloneSelectTM成像系统和MTT法获得的pEC50值具有较好的一致性.与MTT方法相比,基于影像的CloneSelectTM成像分析技术检测快速、无损伤且结果更准确,获取资料不损伤细胞,允许后续其它时间点或动力学检测. 研究提示,这种新的以影像为基础的检测技术可以替代MTT方法,用于分析不同药物的抗细胞增殖活性. 相似文献
8.
9.
流式细胞术研究细胞凋亡的方法与技术 总被引:1,自引:0,他引:1
细胞发生凋亡时,会伴随着一系列形态学、生物化学及分子生物学性质的变化,包括细胞皱缩,核染色质凝聚,细胞膜通透性改变,Caspases激活,线粒体跨膜电位降低,膜磷酯酰丝氨酸外化,胞质Ca2+浓度升高,DNA片段化及含量变化等特点.应用流式细胞术进行细胞凋亡的研究,对于探讨胚胎发育、衰老以及研究肿瘤的发生、发展和转化等病理生理过程和病毒感染及免疫等具有十分重要的意义.本文就细胞凋亡的特征、基于细胞膜功能的流式细胞术检测方法和基于细胞器功能的流式细胞术检测方法等关键性问题进行了阐述. 相似文献
10.
11.
Zhang Rongzhen Zhang Rui Wang Zhibin Li Mengwei Li Kewu 《Plasmonics (Norwell, Mass.)》2022,17(2):457-465
Plasmonics - Diabetes is one of the biggest health problems in the world; in order to control blood in modern biological detection and analysis, most of them use the method of label determination... 相似文献
12.
Plasmonics - Plasmonic metamaterials support the localized surface plasmon resonance (LSPR), which is sensitive to the change in the dielectric environment and highly desirable for ultrasensitive... 相似文献
13.
This work shows that a grating-based surface plasmon (SP) resonance sensing system can exhibit extremely high sensitivity
to detect a small change of refractive index in an analyte. The corresponding sensitivity can be much higher than that of
the prism-based systems. Both analytical calculation and rigorous coupled-wave analysis are used to study the angular sensitivity
of the system. It is found that the system’s sensitivity can be over 600° per unit index change if (1) first-order diffracted
wave is chosen to excite SP mode, (2) large SP resonant angles are used in the operation, and (3) grating filling factor is
selected to be varied between 0.3 and 0.7. Furthermore, the sensing system has the best performance for detecting low-index
analyte with a small change of refractive index. 相似文献
14.
It was found out that the change of refractive index of ambient gas can lead to obvious change of the color of Morpho butterfly's wing. Such phenomenon has been employed as a sensing principle for detecting gas. In the present study, Rigorous Coupled-Wave Analysis (RCWA) was described briefly, and the partial derivative of optical reflection efficiency with respect to the refractive index of ambient gas, i.e., sensitivity of the sensor, was derived based on RCWA. A bioinspired grating model was constructed by mimicking the nanostructure on the ground scale of Morpho didius butterfly's wing. The analytical sensitivity was verified and the effect of the grating shape on the reflection spectra and its sensitivity were discussed. The results show that by tuning shape parameters of the grating, we can obtain desired reflection spectra and sensitivity, which can be applied to the design of the bioinspired refractive index based gas sensor. 相似文献
15.
An Guowen Li Shuguang Yan Xin Zhang Xuenan Yuan Zhenyu Wang Haiyang Zhang Yanan Hao Xiaopeng Shao Yaonan Han Zhicong 《Plasmonics (Norwell, Mass.)》2017,12(2):465-471
Plasmonics - We propose and investigate a photonic crystal fiber (PCF) refractive index sensor with triangular lattice and four large-size channels based on surface plasmon resonance. In such... 相似文献
16.
Plasmonics - This study employed single symmetry split-ring resonator (SRR) to implement biosensor applications. The behavior of the applied mechanism was observed comprehensively by altering the... 相似文献
17.
Xu Liping Luo Lan Wu Hao Luo Zhengchun Chang Tianying Wu Peng Du Chunlei Cui Hong-Liang 《Plasmonics (Norwell, Mass.)》2020,15(3):671-678
Plasmonics - An ultrasensitive surface plasmon resonance (SPR) refractive index detection scheme based on weak value amplification is presented. Extremely low refractive index change... 相似文献
18.
Qin Chen 《Plasmonics (Norwell, Mass.)》2011,6(2):381-385
Conventionally, plasmonic lenses introduce a phase delay distribution across their surfaces by modulating the dimensions of
nanostructures within a metal film. However, there is very limited modulation of the phase delay due to the small dependence
of the mode propagation constant on the structure dimensions. In this paper, a novel design of plasmonic zone plate lenses
(PZPL) with both slit width and refractive index modulation is proposed to enable integrating more slits in a fixed lens aperture
with the extended phase delay range and, therefore, greatly enhance the performance of the devices. More than three-time enhancement
of the light intensity at the focus is achieved compared to the structure with only slit width modulation. Like a conventional
immersion system, a PZPL embedded in a dielectric is found to have a further improved focusing performance, where light is
focused down to a 0.44λ spot using a PZPL with an aperture of 12λ and a focal length of 6λ. Dispersive light-focusing behaviour is also analysed and the modulation of the focal length by colour has a potential application
in stacked image sensors and multi-dimensional optical data storage. 相似文献
19.
Plasmonics - A highly sensitive absorption-based sensor based on folded split-ring metamaterial graphene resonators (FSRMGRs) is designed, and its biomedical application in terahertz (THz) spectrum... 相似文献
20.
Gui-Dong Liu Xiang Zhai Ling-Ling Wang Qi Lin Sheng-Xuan Xia Xin Luo Chu-Jun Zhao 《Plasmonics (Norwell, Mass.)》2018,13(1):15-19
We present a high-performance refractive index sensor based on Fano resonance with a figure of merit (FOM) about 56.5 in all-dielectric metasurface which consists of a periodically arranged silicon rings with two equal splits dividing them into pairs of arcs of different lengths. A Fano resonance with quality factor ~133 and spectral contrast ratio ~100% arises from destructive interference of two antiphase electric dipoles in the two arcs of the split-ring. We can turn on and/or off the Fano resonance with a modulation depth nearly 100% at the operating wavelength of 1067 nm by rotating the polarization of incident light. We believe that our results will open up avenues for the development of applications using Fano resonance with dynamically controllability such as biochemical sensors, optical switching, and modulator. 相似文献