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排序方式: 共有106条查询结果,搜索用时 140 毫秒
81.
一种新型计算机硬盘保护卡 总被引:2,自引:0,他引:2
介绍一种适用于公共机房维护的硬盘保护卡,给出了保护卡中ROM获取BI0S系统控制的方法和启动ROM的构造,并介绍了保护卡对硬盘I/O重新定位和COMS数据保护及保护卡的硬件设计,该卡可防止人为因素和计算机病毒对计算机软件系统的破坏. 相似文献
82.
The pairing of fermions lies at the heart of superconductivity and superfluidity. The stability of these pairs determines the robustness of the superfluid state, and the quest for superconductors with high critical temperature equates to a search for systems with strong pairing mechanisms. Ultracold atomic Fermi gases present a highly controllable model system for studying strongly interacting fermions. Tunable interactions (through Feshbach collisional resonances) and the control of population or mass imbalance among the spin components provide unique opportunities to investigate the stability of pairing-and possibly to search for exotic forms of superfluidity. A major controversy has surrounded the stability of superfluidity against an imbalance between the two spin components when the fermions interact resonantly (that is, at unitarity). Here we present the phase diagram of a spin-polarized Fermi gas of (6)Li atoms at unitarity, experimentally mapping out the superfluid phases versus temperature and density imbalance. Using tomographic techniques, we reveal spatial discontinuities in the spin polarization; this is the signature of a first-order superfluid-to-normal phase transition, and disappears at a tricritical point where the nature of the phase transition changes from first-order to second-order. At zero temperature, there is a quantum phase transition from a fully paired superfluid to a partially polarized normal gas. These observations and the implementation of an in situ ideal gas thermometer provide quantitative tests of theoretical calculations on the stability of resonant superfluidity. 相似文献
83.
Because plants are sessile, they have developed intricate strategies to adapt to changing environmental variables, including light. Their growth and development, from germination to flowering, is critically influenced by light, particularly at red (660 nm) and far-red (730 nm) wavelengths. Higher plants perceive red and far-red light by means of specific light sensors called phytochromes(A-E). However, very little is known about how light signals are transduced to elicit responses in plants. Here we report that nucleoside diphosphate kinase 2 (NDPK2) is an upstream component in the phytochrome signalling pathway in the plant Arabidopsis thaliana. In animal and human cells, NDPK acts as a tumour suppressor. We show that recombinant NDPK2 in Arabidopsis preferentially binds to the red-light-activated form of phytochrome in vitro and that this interaction increases the activity of recombinant NDPK2. Furthermore, a mutant lacking NDPK2 showed a partial defect in responses to both red and farred light, including cotyledon opening and greening. These results indicate that NDPK2 is a positive signalling component of the phytochrome-mediated light-signal-transduction pathway in Arabidopsis. 相似文献
84.
85.
Yasuda K Miyake K Horikawa Y Hara K Osawa H Furuta H Hirota Y Mori H Jonsson A Sato Y Yamagata K Hinokio Y Wang HY Tanahashi T Nakamura N Oka Y Iwasaki N Iwamoto Y Yamada Y Seino Y Maegawa H Kashiwagi A Takeda J Maeda E Shin HD Cho YM Park KS Lee HK Ng MC Ma RC So WY Chan JC Lyssenko V Tuomi T Nilsson P Groop L Kamatani N Sekine A Nakamura Y Yamamoto K Yoshida T Tokunaga K Itakura M Makino H Nanjo K Kadowaki T Kasuga M 《Nature genetics》2008,40(9):1092-1097
We carried out a multistage genome-wide association study of type 2 diabetes mellitus in Japanese individuals, with a total of 1,612 cases and 1,424 controls and 100,000 SNPs. The most significant association was obtained with SNPs in KCNQ1, and dense mapping within the gene revealed that rs2237892 in intron 15 showed the lowest Pvalue (6.7 x 10(-13), odds ratio (OR) = 1.49). The association of KCNQ1 with type 2 diabetes was replicated in populations of Korean, Chinese and European ancestry as well as in two independent Japanese populations, and meta-analysis with a total of 19,930 individuals (9,569 cases and 10,361 controls) yielded a P value of 1.7 x 10(-42) (OR = 1.40; 95% CI = 1.34-1.47) for rs2237892. Among control subjects, the risk allele of this polymorphism was associated with impairment of insulin secretion according to the homeostasis model assessment of beta-cell function or the corrected insulin response. Our data thus implicate KCNQ1 as a diabetes susceptibility gene in groups of different ancestries. 相似文献
86.
Green JE Choi JW Boukai A Bunimovich Y Johnston-Halperin E DeIonno E Luo Y Sheriff BA Xu K Shin YS Tseng HR Stoddart JF Heath JR 《Nature》2007,445(7126):414-417
The primary metric for gauging progress in the various semiconductor integrated circuit technologies is the spacing, or pitch, between the most closely spaced wires within a dynamic random access memory (DRAM) circuit. Modern DRAM circuits have 140 nm pitch wires and a memory cell size of 0.0408 mum(2). Improving integrated circuit technology will require that these dimensions decrease over time. However, at present a large fraction of the patterning and materials requirements that we expect to need for the construction of new integrated circuit technologies in 2013 have 'no known solution'. Promising ingredients for advances in integrated circuit technology are nanowires, molecular electronics and defect-tolerant architectures, as demonstrated by reports of single devices and small circuits. Methods of extending these approaches to large-scale, high-density circuitry are largely undeveloped. Here we describe a 160,000-bit molecular electronic memory circuit, fabricated at a density of 10(11) bits cm(-2) (pitch 33 nm; memory cell size 0.0011 microm2), that is, roughly analogous to the dimensions of a DRAM circuit projected to be available by 2020. A monolayer of bistable, [2]rotaxane molecules served as the data storage elements. Although the circuit has large numbers of defects, those defects could be readily identified through electronic testing and isolated using software coding. The working bits were then configured to form a fully functional random access memory circuit for storing and retrieving information. 相似文献
87.
Release of a vascular-inhibitory factor from endothelial cells (EC), different from endothelium-derived relaxant factor (EDRF), was identified through use of a two-bath system. This two-bath system precluded the effects of oxygen-free radicals that appear when electrical field stimulation (EFS) is directly imposed on detector muscle. 相似文献
88.
天然树脂紫胶的热裂解-气相色谱特性 总被引:4,自引:0,他引:4
研究了有机碱试剂,氢氧化四甲铵(tetramethylammonium
hydroxide TMAH)共存下的反应热裂解气相色谱(Py-GC)应用于天然树脂紫胶的化学组成分析.并在反应Py-GC测得的化学组成的基础上,应用主成分分析(principal
component analysis,PCA)对印度和泰国产紫胶进行产地识别分析. 相似文献
89.
开发了一种用于液体和气体样品中微量组分富集的大容量固相萃取装置.在小金属钛管(内径1.2mm外径1.6mm长6~30mm)的外壁键合上一层聚二甲基硅氧烷(厚0.32mm),就能有效地萃取多种有机物,结果可用热解吸-气相色谱-质谱联检. 相似文献
90.
Myopia and ambient lighting at night. 总被引:9,自引:0,他引:9