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排序方式: 共有573条查询结果,搜索用时 15 毫秒
1.
P.Y. Raval P.R. Pansara A.R. Makadiya N.H. Vasoya S.N. Dolia K.B. Modi 《Ceramics International》2018,44(15):17667-17674
The consequences of high energy mechanical milling, microwave-assisted heating and rapid thermal cooling on magnetic ordering in polycrystalline CaCu3Ti4O12 cubic perovskite have been investigated by means of X-ray powder diffractometry (300?K), dc magnetization in field – cooled and zero – field cooled modes (H = 100?Oe and 1000?Oe, T?=?5–300?K) (M – T curves) and M – H loop characteristics (T?=?5?K and 300?K, Hmax = 70?kOe). The M – T curves of unmilled and 16?h milled samples show pure antiferromagnetic and weak ferromagnetic ordering, respectively, 1?h and 6?h milled samples demonstrate the coexistence of both the phases while microwave-assisted and quenched samples exhibit classic antiferromagnetic transition and a low temperature paramagnetic–like contribution with different weights, well supported by the M – H loop characteristics. The observed transformations in the magnetic ordering are attributed to the ball-milling induced stress which curtails hybridization of empty Ti-3d orbitals with Cu-3d and O-2p orbitals and secondary phase formation. Oxygen vacancies associated with bound magnetic polarons originate ferromagnetism in the milled samples while unpaired electrons inhabited at the empty sites are the cause of paramagnetic centers. The low-temperature Curie – tail in M – T curve for quenched and microwave assisted samples is attributed to Ti3+ cations. 相似文献
2.
Recent advances in gene technology have helped to identify novel proteins and allowed study of their distribution and functions in the mammalian brain. One class of these proteins is that of transporters, which exist in plasma and organellar membranes of neurons and other cells to move substances selectively across membranes. These transporters can be categorized further into subclasses by their structural property, substrate selectivity, and site of action. Some of them have been identified in the hypothalamus, which is the only brain site where a neural signal is converted to a humoral one, namely, a hormone for a target organ. This unique neural mechanism has long attracted attention as the neuroendocrine system, part of which has been extensively studied as the hypothalamic-neurohypophysial system involved in secretion of vasopressin and oxytocin. However, transporters in this system have been less well studied. A morphological examination of novel transporters would give us cues to a better understanding of the neuronal organization and function of the system. In this review, we first summarize recent findings on expression of transporter gene and immunoreactivity in the hypothalamus. In the second part, we explain our observations on two vesicular glutamate (inorganic phosphate) transporters (BNPI and DNPI) in the supraoptic and paraventricular nuclei and neurohypophysis. Further study of these and other transporters will provide a basis on which to reevaluate the organization and function of the hypothalamic-neurohypophysial system. 相似文献
3.
Gleevec是抑制致癌的融合蛋白BCR-ABL的一种分子靶向治疗药物,BCR-ABL是一种与慢性髓细胞性白血病(CML)有关的酪氨酸激酶抑制剂。用Gleevec选择性地抑制BCR-ABL活性在治疗CML中显示出很好的效果,特别是在CML慢性期,因此,监测疗效非常重要。现就Gleevec的研究进展及如何监测其在CML中的疗效作一简单综述。 相似文献
4.
5.
Youri Oh Hoyong Jung Hyejin Kim Jihyun Baek Joonhong Jun Hyunwook Cho Daseul Im Jung-Mi Hah 《International journal of molecular sciences》2021,22(8)
Polo-like kinase 1 (PLK1) plays an important role in cell cycle progression and proliferation in cancer cells. PLK1 also contributes to anticancer drug resistance and is a valuable target in anticancer therapeutics. To identify additional effective PLK1 inhibitors, we performed QSAR studies of two series of known PLK1 inhibitors and proposed a new structure based on a hybridized 3D-QSAR model. Given the hybridized 3D-QSAR models, we designed and synthesized 4-benzyloxy-1-(2-arylaminopyridin-4-yl)-1H-pyrazole-3-carboxamides, and we inspected its inhibitory activities to identify novel PLK1 inhibitors with decent potency and selectivity. 相似文献
6.
O'Reilly-Wapstra JM Potts BM McArthur C Davies NW Tilyard P 《Journal of chemical ecology》2005,31(3):519-537
Hybridization in plants provides an opportunity to investigate the patterns of inheritance of hybrid resistance to herbivores, and of the plant mechanisms conferring this resistance such as plant secondary metabolites. We investigated how inter-race differences in resistance of Eucalyptus globulus to a generalist mammalian herbivore, Trichosurus vulpecula, are inherited in their F1 hybrids. We assessed browsing damage of three-year-old trees in a common environment field trial on four hybrid types of known progeny. The progency were artificial intra-race crosses and reciprocal inter-race F1 hybrids of two geographically distinct populations (races) of E. globulus; north-eastern Tasmania and south-eastern Tasmania. Populations of trees from north-eastern Tasmania are relatively susceptible to browsing by T. vulpecula, while populations from south-eastern Tasmania are more resistant. We assessed the preferences of these trees in a series of paired feeding trials with captive animals to test the field trial results and also investigated the patterns of inheritance of plant secondary metabolites. Our results demonstrated that the phenotypic expression of resistance of the inter-race F1 hybrids supported the additive pattern of inheritance, as these hybrids were intermediate in resistance compared to the pure parental hybrids. The expression of plant secondary metabolites in the F1 hybrids varied among groups of individual compounds. The most common pattern supported was dominance towards one of the parental types. Together, condensed tannins and essential oils appeared to explain the observed patterns of resistance among the four hybrid types. While both chemical groups were inherited in a dominant manner in the inter-race F1 hybrids, the direction of dominance was opposite. Their combined concentration, however, was inherited in an additive manner, consistent with the phenotypic differences in browsing. 相似文献
7.
按随机引物法以地高辛标记HBV DNA探针,与按缺口翻译法以~(32)P标记的探针进行了比较。这两种探针与乙肝血源疫苗及患者血清标本中HBV DNA进行杂交,结果两种探针均可要出1pg同源序列DNA,而地高辛标记的探针,在0.1Pg水平仍可呈现弱着色反应。该探针在一20℃储存6个月,其敏感性不减弱。这种探针在常规诊断实验室更易推广使用。 相似文献
8.
DNA电化学生物传感器的研究进展 总被引:1,自引:0,他引:1
介绍了DNA电化学生物传感器的组成及原理,综述了近年来单链DNA的固定以及杂交信号的电化学检测方面的研究进展,探讨了纳米材料、纳米技术在DNA电化学生物传感器的制备及应用中发挥的作用,并对DNA电化学生物传感器的发展方向进行了展望. 相似文献
9.
The reconstruction of DNA sequences from DNA fragments is one of the most challenging problems in computational biology. In recent years the specific problem of DNA sequencing by hybridization has attracted quite a lot of interest in the optimization community. Several metaheuristics such as tabu search and evolutionary algorithms have been applied to this problem. However, the performance of existing metaheuristics is often inferior to the performance of recently proposed constructive heuristics. On the basis of these new heuristics we develop an ant colony optimization algorithm for DNA sequencing by hybridization. An important feature of this algorithm is the implementation in a so-called multi-level framework. The computational results show that our algorithm is currently a state-of-the-art method for the tackled problem. 相似文献
10.
This brief paper reports a hybrid algorithm we developed recently to solve the global optimization problems of multimodal
functions, by combining the advantages of two powerful population-based metaheuristics—differential evolution (DE) and particle
swarm optimization (PSO). In the hybrid denoted by DEPSO, each individual in one generation chooses its evolution method,
DE or PSO, in a statistical learning way. The choice depends on the relative success ratio of the two methods in a previous
learning period. The proposed DEPSO is compared with its PSO and DE parents, two advanced DE variants one of which is suggested
by the originators of DE, two advanced PSO variants one of which is acknowledged as a recent standard by PSO community, and
also a previous DEPSO. Benchmark tests demonstrate that the DEPSO is more competent for the global optimization of multimodal
functions due to its high optimization quality.
Supported by the National Natural Science Foundation of China (Grant No. 60374069), and the Foundation of the Key Laboratory
of Complex Systems and Intelligent Science, Institute of Automation, Chinese Academy of Sciences (Grant No. 20060104) 相似文献