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941.
ZHANG Shu RONG Mongtian 《武汉大学学报:自然科学英文版》2007,12(2):299-302
Current uplink power control algorithm of code division multiple access (CDMA) time division duplex(TDD) system contains signal-to-interference-ratio(SIR) and interference measurement, which is based on history information. However, the adjustment of transmission power of one user equipment(UE) will affect SIR of the others, because the power control is done independently of the power adjustment of other UE's. So the convergence speed of power control is not fast and the system performance degrades. In the proposed algorithm, all UE's assigned in same time slot adjust their transmission power based on current information, which takes into account the adjustments of transmission power of all UE's. The simulation results indicated that the proposed algorithm outperforms the old algorithm. 相似文献
942.
服务质量管理模式的研究 总被引:10,自引:0,他引:10
阐述了服务质量的含义,然后构造出一个以顾客为中心的服务质量管理模式。它包括一个服务三角形,由服务战略,服务系统、服务人员三个因素构成,这三个因素都面向顾客这个中心,彼此又相互关联。 相似文献
943.
β-烷基对卟吩异构化的取代基效应 总被引:5,自引:3,他引:5
用AM1 MO方法和过渡状态理论研究了β-甲基和β-乙基对卟吩异构化反应的影响.具体计算了卟吩和这2个β-烷基卟啉异构化的反应势能剖面, 以及卟吩反应与它们的反应速率常数的比值.结果表明, β-烷基取代后, 活化焓因素对异构化反应是不利的,而活化熵是一个影响权重更大的因素.活化熵变化的本质是由β-烷基引起的相对构型无序造成的. 相似文献
944.
H2O2诱导烟草悬浮细胞的凋亡 总被引:7,自引:0,他引:7
烟草悬浮细胞经不同浓度的过氧化氢处理发现 ,当用 6mmol L的H2 O2 处理时从形态学上可观察到明显的染色质凝聚 ,细胞质皱缩和细胞核解体等现象 ;DNA电泳结果显示发生凋亡的细胞基因组DNA被降解形成明显的DNA梯状条带 ,从而表现出典型的细胞凋亡特征 .其他高浓度的处理也有以上特征 ,但细胞坏死数目也相对增多 ,因此本研究认为 6mmol L的H2 O2 处理 2 4h能够非常有效地诱导烟草悬浮细胞的凋亡 . 相似文献
945.
Loess in the Tian Shan and its implications for the development of the Gurbantunggut Desert and drying of northern Xinjiang 总被引:8,自引:0,他引:8
Xiaomin Fang Zhentao Shi Shengli Yang Maodu Yan Jijun Li Ping’an Jiang 《科学通报(英文版)》2002,47(16):1381-1387
Eolian loess is widely distributed on the various geomorphic surfaces between 700–2400 m a.s.l. on the northern slope of the
Tian Shan. It is formed in a synchronous manner with dust transported from the Gurbantunggut Desert in the Junggar Basin.
The thickest section of loess was found in the Shawan and Shihezi regions. Paleomagnetic and climatic proxy analyses of over
71 m of a loess-paleosol sequence on the highest terrace of the Qingshui He (River) in the Shawan show that the paleomagnetic
Bruhues/Matuyama (B/M) boundary lies at the bottom of paleosol S8, at a depth of 69.5 m, and the bottom of the sequence was
estimated to be ∼0.8 Ma. This implies that the extremely dry climatic conditions in the Junggar Basin and the initial Gurbantunggut
Desert were present at least by 0.8 Ma. High-resolution grain size series demonstrate that this area and desert expansion
experienced two dramatic periods of desert expansions that occurred at ∼0.65 Ma and 0.5 Ma, respectively; and the subsequent
continuous enhancement led to the environment presently observed. This tremendous environmental effect, caused by large-scale
expansion of the desert and arid region of inner Asia, might be an important driving force for the global temperature drop
that occurred in the mid-Pleistocene. 相似文献
946.
PGE patterns of ores of Dajing Cu-polymetallic deposit in Linxi County,Inner Mongolia: Indicator to source of metallogenic elements 总被引:1,自引:0,他引:1
By comparing PGE patterns of sulfide ores with that of basic-ultrabasic dikes occurring in the Dajing Cu-polymetallic deposit,
we discover that there are similar positive slopes between the basic-ultrabasic dikes and the black ores composed mainly of
sphalerite and galena, reflecting affinity of their source. The PGE patterns of the yellow ores composed basically of chalcopyrite,
arsenopyrite and pyrite are actually different. One is close to the pattern of the mantle lherzolite, and others resemble
the pattern of the basic rocks. However, the concentrations of Ru are higher in the yellow ores, reflecting that sulfur attains
or approaches saturation in their parent magma. The PGE characteristics of ores and dikes show that the magmas derived from
the deep of crust and the metallogenic elements were supplied mainly by growth material of the crust. In addition, the mantle-derived
magma also offered some elements. 相似文献
947.
To study the relations between male infertility and centrosome protein (centrin) and the functions of centrin in spermatogenesis,
the matured spermatozoa of 10 normal male people and 18 male infertility patients were stained by immunofluorescence labeling
antibody against centrin. The results showed that two fluorescence signal dots appeared in the normal male spermatozoa and
were located at the base of flagellum. They are proximal centriole and distal centriole. However, in some spermatozoa of the
male infertility, centrin protein was located abnormally at the base of flagellum and its staining signals were spread, the
normal proximal and distal centrioles were confused and could not be recognized separately. These results suggest that abnormality
of centrosome protein may be related to male infertility. This discovery may be used as a marker of abnormal sperm and male
infertility. 相似文献
948.
B.Wünnemann 《科学通报(英文版)》2002,47(23):1946-1956
Comprehensive field investigations and laboratory analyses show that palaeolakes, including fresh- mesohaline water Megalake Tengger and other semi-con- nected, isolated water bodies, during late Pleistocene covered an area of more than 20000 km2, which is more than half of the Tengger Desert in NW China. Stratigraphic correlation and chronological evidence indicate that before ca. 42000 aBP the area was more arid. The palaeolakes started to develop around 40000 uncal. 14C aBP but until 37000 14C aBP their scope was limited. High water levels established from 35000 14C aBP lasted until 22000 14CaBP. Lake levels regressed between 22000 and 20000 14C aBP but transgressed from 20000 to 18600 14C aBP. Subsequently, water level declined further and the Megalake Tengger finally desiccated at around 18000 14C aBP. Megalake Tengger possessed a fresh-mesohaline water property, implying that the regional precipitation increased significantly. During the period of Megalake Tengger, the climate was warmer-humid than present. The annual rainfall was 250 to 350 mm more than that of today and the temperature was 1.5 to 3.0℃ higher. 相似文献
949.
Experimental study on patterns of fault interaction 总被引:3,自引:0,他引:3
Based on the data of strain field, fault slip and acoustic emission during the deformation of some fault models, the fault interaction patterns are studied. The experiments reveal four patterns of fault interaction, i.e. static promotion or delay of earthquake, creep triggering, dynamic triggering and dynamic loading-relaxation. Promotion and delay of earthquake caused by fault interaction and mechanical property of fault combinations are preliminarily analyzed from the perspective of series and parallel connection of faults, and the relationship between patterns of fault interaction and mechanical and material properties of fault is discussed. 相似文献
950.
A fast and effective model for predicting the salt and pH dependent properties of protein complexes is presented. It is based on the formal charge parameter sets of ionizable groups and applied in conjunction with the finite difference Poisson-Boltzmann (FDPB) method to calculate the electrostatic interactions. All simulations were performed on the native 2Zn insulin and its fast-acting mutants such as B9D (B9Ser→ Asp), B9E (B9Aer→ Giu), B9EB10D (B9Ser→Glu, B10His→ Asp), and B10D (B10His → Asp). The salt and pH dependent properties of these dimers were analyzed from the aspect of electrostatic interaction, and the theoretical basis of the fast-acting behavior of these mutants was explained. It is found that the results agree well with experimental observations. 相似文献