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1.
据报载，海湾战争期间，美国军事测绘部门是国防部7大部局中惟一24小时全天运行的保障机构，向多国部队提供的地图达上亿张。数字地图不仅参与了战场准备、作战决策、作战指挥、后勤保障等各个环节的全过程，而且被跨国异地作战的多国部队视为“第二生命”。可以说，在战场上如果没有数字地图，就意味着指挥员成了“睁眼瞎”，作战部队寸步难行，精确制导武器无法准确命中，精确定位系统失去目标。 相似文献
2.
本文依据紫果云杉(Picea purpurea Mast)残木、部分地层测年资料、湖成地貌,结合树木年轮和湖水观测资料,探讨近8000年来青海湖演变史并概略预测其发展趋势:8000—3500a.B.P.为暖湿期,3500a.B.P.以来渐趋冷干—干旱,600a.B.P.以来又几经暖湿—冷干的更替;在不考虑温室效应的前提下,大致在133年后湖水达补耗水量平衡期;在温室效应的影响下,湖水将提前于下世纪中叶进入补耗平衡期。 相似文献
3.
H2 photoproduction and nitrogenase activities in two strains ofAnabaena variabilis marked wild type ATCC 29413 and mutant PK84 exposed to thermal stress (temperature higher than the normal incubation temperature of 30°C) were studied. Cultures of both strains collected from any interval of logarithmic growth phase exhibited high H2 photoproduction and nitrogenase activities when exposed to limited time heat shock during the assay process. In contrast, the algal H2 photoproduction rate of both strains fluctuated with long term thermal stress caused by increasing the growth temperature from 30°C to 36°C. The changes of nitrogenase (the key H2 photobiosynthetic enzyme) activities in the mutant PK84 showed variation tendency similar to that of H2 photoproduction during exposure to thermal stress, indicating that fluctuation of H2 photoproduction in the mutant was mainly due to the variation of nitrogenase activities. A temporary maximal H2 photoproduction in the mutant PK84 (wild type ATCC29413) was observed when cells grew at 36°C for 14 (6) days. However, the responses of nitrogenase activities in the wild type to thermal stress were not completely similar to those in the mutant in spite of similar variations of H2 photoproduction in both strains. The data obtained in these studies suggested that the activities of other enzymes (in the wild strain) involved in H2 photoproduction were affected by thermal stress since H2 photoproduction maximized or dropped to 0 without variation tendency similar to that of nitrogenase activities. Furthermore, an enhancement of H2 photoproduction speed of the mutant strain cultured in a 4.4 L laboratory photobioreactor was also observed when it was subjected to short time continuous charge of argon, and temperature rise. All these results indicated that high temperature plays an important role in the photo-autotrophic H2 photoproduction, and that long term thermal stress is unfavourable for net H2 photoproduction in both strains ofA. variabilis though short-time heat shock is conducive to H2 photoproduction. 相似文献
4.
Five species of Asterometrids (Crinoidea) collected from China are recorded. One of them is described as a new genus and new species named Sinometra acuticirra, and three are recorded from China for the first time. 相似文献
5.
The characteristics and infraciliature of a new euplotid ciliate,Euplotes qingdaoensis n.sp.,discovered from the coastal waters of Jiaozhou Bay,northern China,were studied using live observation and silver impregnation.The new marine species is characterized by a slightly fl attened body(90–110 μm×70–80 μm,in vivo),an adoral zone of 26–29 membranelles,10 strong frontoventral and fi ve transverse cirri,two caudal cirri,a single left marginal cirrus,seven dorsal kineties,a middle kinety with about 15 pairs of basal bodies,a silverline system of the double-eurystomus type,and a C-shaped macronucleus. 相似文献
6.
A new species of goneplacid crab, Paragoneplax chenae, is described, based on collections from the Nansha Islands, South China Sea. P. chenae closely resembles its only congener P. serenei (Zarenkov, 1972) in general appearance. They are distinguishable from each other by the male abdominal and gonopodal characters. 相似文献
7.
The propagation of long-waves, such as tidal waves from the coastal ocean into shallow estuarine waters, often produces asymmetries
of velocity and water level in time series resulting in long-wave breaking. Tian (1994) studied the mechanism of long-wave
breaking in an infinite channel with constant depth, considering nth power bottom friction. This study is for the case of a half infinite channel with bottom slope, taking linear bottom friction
into account. The wave breaking time and wave breaking location are estimated and the criteria for long-wave breaking in this
particular case are obtained. The results obtained can also be easily applied to the case considering wind stress. 相似文献
8.
The morphology and infraciliature of a new marine colepid ciliate, Apocoleps magnus gen. nov., spec. nov., are described based on living observations and silver impregnations. The new genus Apocoleps is characterized by having 8 (vs. 6 in most other related genera) armour tiers, spines at both ends of the cell, 3 adoral organelles and plates with 4 reniform uni-windows. Apocoleps magnus spec. nov. is defined by the following features: body elongated and slightly curved, about 100–120μm× 35–45 μm in vivo; an... 相似文献
9.
A new species of Proteocephalus from the fish Sinocyclocheilus grahami tingi, a subspecies endemic to Fuxian Lake in Southwest China, is described. This is the first report of cestode from this host. The new species differs from P. exiguus, P. Longicollis, P. parasiluri and P. torulosus, the only other species of Proteocephalus currently reported from China, by lacking an apical sucker, from P. exiguus by having 45–108 rather than 24–54 testes per proglottis, and a maximum of 15 rather than 28 uterine diverticula; from P.longicollis by having an average of 45–108 rather than 75–115 testes per proglottis and testes being in a single layer instead of 2 layers;
and from P. torulosus by having 45–108 instead of 150 testes per proglottis and testes being in 3–4 layers; and from P. parasiluri by having 45–108 rather than 180 testes per proglottis. It resembles P. percae, P. pollanicola, and P. thymalli in number of testes and uterine diverticula, but differs by lacking an apical sucker. Proteocephalus thymalli, like the new species, has a vagina that opens dorsally to the cirrus sac, but P. thymalli slao has postovarian testes, which the new species lacks. The possible significance of parasitological examinations of the
other two subspecies of S. grahami in two lakes close to Fuxian Lake is discussed in relation to host speciation and coevolution of the host-parasite system. 相似文献
10.
SO2 is very rapidly hydrated to sulfurous acid in water solution at pH value above 6.0,whereby sulfite is yielded from the disassociation of protons.We aimed to improve the sulfite transformation efficiency and provide a basis for the direct utilization of SO2 from flue gas by a microalgal suspension.Chlorella sp.XQ-20044 was cultured in a medium with 20 mmol/L sodium sulfite under different physicochemical conditions.Under light conditions,sulfite concentration in the algal suspension reduced linearly over time,and was completely converted into sulfate within 8 h.The highest sulfite transformation rate(3.25 mmol/(L·h)) was obtained under the following conditions:35°C,light intensity of 300μmol/(m2·s),NaHCO3 concentration of 6 g/L,initial cell density(OD540) of 0.8 and pH of 9-10.There was a positive correlation between sulfite transformation rate and the growth of Chlorella,with the conditions favorable to algal growth giving better sulfite transformation.Although oxygen in the air plays a role in the transformation of SO2-3 to SO2-4,the transformation is mainly dependent on the metabolic activity of algal cells.Chlorella sp.XQ-20044 is capable of tolerating high sulfite concentration,and can utilize sulfite as the sole sulfur source for maintaining healthy growth.We found that sulfite 20 mmol/L had no obvious effect on the total lipid content and fatty acid profiles of the algae.Thus,the results suggest it is feasible to use flue gas for the mass production of feedstock for biodiesel using Chlorella sp.XQ-20044,without preliminary removal of SO2,assuming there is adequate control of the pH. 相似文献
11.
1 Introduction In recent years, carotenoids have received increasing attention as they have extensive use in medicine, cosmetic, chemistry, food industry and feed industry. In industry, carotenoid and astaxanthin can be used as the additives of food or feeds. Carotenoids can also serve as the precursor of vitamin A in mammals. In recent years, many types of carotenoid have aroused extensive interest because of their many beneficial effects on human health. For in-stance, lycopene and astaxant… 相似文献
12.
Journal of Oceanology and Limnology - Magnetotactic bacteria(MTB) display magnetotaxis ability because of biomineralization of intracellular nanometer-sized, membrane-bound organelles termed... 相似文献
13.
According to the known sequence of iron stress-induced gene (isiAB operon), we cloned its 1.5 kb fragment by PCR, and used this fragment as integration homologous fragment. After several steps of subcloning donor DNA into theisiAB fragment, a donor plasmid pZL which could be integrated into the chromosomal DNA ofSynechococcus sp. PCC7942 was constructed. In order to express the heterologous gene at a high level through the integration platform system, we constructed the donor DNA by the following steps. We cloned the strong promoter (240 bp) of heat shock genegroESL operon fromSynechococcus sp. PCC7942 by PCR. Then subcloned the multiple cloning sites (MCS),rbcS polyA into the downstream of thegroESL promoter. The kanamycin resistance gene, as the marker gene, was also subcloned into the donor DNA. Thus, in the donor plasmid pZL, the integration homologous fragment and several expression elements, such asgroESL promoter, MCS,rbcS polyA terminator and kanamycin resistance gene, were all included. After naturally transformed and introduced the donor plasmid pZL intoSynechococcus sp. PCC7942, as in the pZL, the donor DNA sequence is flanked by two DNA fragments (0.4 kb and 0.7 kb) homologous to theisiAB fragment ofSynechococcus sp. PCC7942, the homologous DNA can recombine with the chromosomal DNA. After screening by kanamycin, the transformants which integrated the heterologous DNA were selected. The efficiency of transformation is about 1×10−6. By southern blot analysis, it was confirmed that the donor DNA had been integrated into the chromosomal DNA ofSynechococcus sp. PCC7942, located on the site of theisiAB gene, and can be replicated with the chromosomal DNA. 相似文献
14.
An aerobic, Gram-negative bacterium, strain 2-5~T, was isolated from a crude oil-contaminated marine sponge collected near Dalian Bay, China, and subjected to a polyphasic taxonomic investigation. Cells of strain 2-5~T were non-spore forming, non-motile, rods 0.2–0.3 μm wide and 1.1–1.2μm long. Strain 2-5~T grew well on nutrient agar, ~TSA, R2 A agar and LB agar. Colonies of strain 2-5~T on LB agar were circular, smooth with entire margins, non-transparent and pale yellow after 3 d of incubation at 30℃. Growth of strain 2-5~T occurred in LN medium with 0–6% Na Cl; no growth occurred in the presence of 8.0% NaCl. Strain 2-5~T grew at 15–42℃ and at pH 6.0–8.0. Comparative 16 S r RNA gene sequence analysis showed that strain 2-5~T clustered with the species of the genus Lysobacter. Its closet neighbors were the type strains of Lysobacter concretionis KC~TC 12205~T(97% similarity), Lysobacter arseniciresistens ZS79~T(96%), and Lysobacter defluii APB-9 ~T(96%). ~The value for DNA-DNA relatedness between strain 2-5~~T and L. concretionis KC~TC 12205 ~T was 23%. Branched fatty acids iso-C16: 0, iso-C15: 0, iso-C11: 0 3-OH, iso-C17: 1ω9c and iso-C11: 0 were found to be predominant. ~The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. Strain 2-5~T had a DNA G+C content of 63.8 mol%. On the basis of the phenotypic, chemotaxonomic, DNA-DNA hybridization and phylogenetic data, strain 2-5~T represents a novel species of the genus Lysobacter, for which the name Lysobacter hymeniacidonis sp. nov. is proposed. ~The type strain is 2-5~T(=CGMCC 1.12190 ~T = JCM 18137~T). 相似文献
15.
β-agarase AgaB appears to represent a new family of glycoside hydrolase; it is structurally and functionally different from other known agarases. In the present study, AgaB was expressed with a temperature-inducible expression system in E. coli BL21 (DE3) as a fusion protein bearing a C-terminal hexahistidine tag. The protein existed mainly in the form of inclusion body.After being washed and solubilized, AgaB in inclusion body was denatured and purified to electrophoretic purity by immobilized metal affinity chromatography. The purified AgaB was then refolded using a simple pulse dilution method, and the refolded AgaB showed a high specific hydrolysis activity of about 1600 units/mg protein. Forty milligrams of refolded pure protein were obtained from 1L of culture. 相似文献
16.
In recent years, red tides occurred frequently in coastal areas worldwide. Various methods based on the use of clay, copper sulfate, and bacteria have been successful in controlling red tides to some extent. As a new defensive agent, marine microorganisms are important sources of compounds with potent inhibitory bioactivities against red-tide microalgae, such as Gymnodinium sp. （Pyrrophyta）. In this study, we isolated a marine bacterium, HSB07, from seawater collected from Hongsha Bay, Sanya, South China Sea. Based on its 16S rRNA gene sequence and biochemical characteristics, the isolated strain HSB07 was identified as a member of the genus Halomonas. A crude ethyl acetate extract of strain HSB07 showed moderate inhibition activity against Gymnodinium sp. in a bioactive prescreening experiment. The extract was further separated into fractions A, B, and C by silica gel column chromatography. Fractions B and C showed strong inhibition activities against Gymnodinium. This is the first report of inhibitory activity of secondary metabolites of a Halomonas bacterium against a red-tide-causing microalga. 相似文献
17.
During an expedition to a seamount at Caroline Plate in the tropical Western Pacific,a new species of Tritonia was sampled from the upper bathyal zone at depth of 970-1 262 m.This new species,Tritonia iocasica sp.nov.,represents the first tritoniid nudibranch known to feed on octocoral of the family Melithaeidae.The species is up to 120 mm in length,pinkish in color;with the rhinophoral sheath divided into several petaliform extensions;veil with,about 18 elongate digitiform processes;notal margin with17-19 pairs of secondary gills;anus located below the 5~(th) and 6~(th) secondary gills,and the genitalia below the 3~(rd) secondary gill on the right side of the body.Based on these external features,T.iocasica sp.nov.can be dearly distinguished from all previously described members of the genus.Phylogenetic analyses of two mitochondrial(COI,16 S rRNA) and a nuclear(H3) genes using Bayesian inference,maximum likelihood,and species delimitation analysis also support the separation of T.iocasica sp.nov.from its congeners. 相似文献
18.
We used preliminary data to estimate the growth volume of artificially reforested Pinus densiflora in a post-fire area on three different contour conditions. We compared the growth of P. densiflora on a south-facing slope(Ssth), north-facing slope(Snth) and ridge area(Ridge), using 7 trees selected from each stand aspect. The tree height, diameter and growth volume were measured and the dry weight of each plant part were compared and analyzed. The results revealed that the total dry weight was highest on Ssth(5992.3 g), followed by Snth(4833.2 g) and lowest on Ridge(3160.1 g). The height growth was highest on Snth(285.8 cm), followed by Ssth(274.5 cm) and lowest on Ridge(211.5 cm). The diameter growth was greatest on Ssth(7.37 cm), followed by Snth(7.10 cm) and lowest on Ridge(5.72 cm). The volume growth was highest on Ssth(4257.7 cm3), followed by Snth(3750.7 cm3) and lowest on Ridge(2093.7 cm3). Therefore, we should consider and include the concept of slope orientation together with differences in habitat environments in afforestation projects when creating artificial forests with P. densiflora. These study results can serve as important preliminary data for future establishment of artificial forest of P. densiflora in a post-fire plantation. 相似文献
19.
分析了当前主流Web GIS中普遍存在的问题,并基于Web Service和．NET技术。提出了新一代的网络地理信息系统技术框架——面向服务的Web GIS软件平台框架,该框架体现了“服务即是软件,软件即是服务”的全新理念。最后介绍了基于Web Service和．NET技术的新一代Web GIS平台——SuperMap IS．NET的设计与实现。 相似文献
20.
How to accurately simulate the distribution of forest species based upon their biological attributes has been a traditional biogeographical issue.Forest gap models are very useful tools for examining the dynamics of forest succession and revealing the species structure of vegetation.In the present study,the GFSM（Gongga Forest Succession Model） was developed and applied to simulate the distribution,composition and succession process of forests in 100 m elevation intervals.The results indicate that the simulated results of the tree species,quantities of the different types of trees,tree age and differences in DBH（diameter at breast height） composition were in line with the actual situation from 1400 to 3700 MASL（meters above sea level） on the eastern slope of Mt.Gongga.Moreover,the dominant species in the simulated results were the same as those in the surveyed database.Thus,the GFSM model can best simulate the features of forest dynamics and structure in the natural conditions of Mt.Gongga.The work provides a new approach to studying the structure and distribution characteristics of mountain ecosystems in varied elevations.Moreover,the results of this study suggest that the biogeochemistry mechanism model should be combined with the forestsuccession model to facilitate the ecological model in simulating the physical and chemical processes involved. 相似文献
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