内蒙古典型草原地上净初级生产力估测及模型模拟的研究

地上净初级生产力（ANPP）是陆地生态系统碳循环的重要组成部分，但由于估测ANPP的方法不同使得对ANPP的估测值存在很大的不确定性。本文采用3种方法（群落中所有种群当年最大地上生物量之和（ANPPC1）、当年群落最大地上生物量（ANPPC2）以及每年固定日期（8月30日）的地上生物量（ANPPC3））在种群、功能群和群落水平上分别对连续19年（1980～1998）的内蒙古羊草和大针茅草原生态系统功能（如ANPP、植物多样性和水分利用效率（WUE））的动态变化进行了比较分析，同时探讨了不同估测方法下气候和放牧对ANPP的影响，在此基础上利用DNDC模型进行了ANPP的模拟和敏感性分析研究，主要结果包括： 在羊草和大针茅草原群落中，不同主要植物种群或功能群多年平均地上最大生物量出现的时间不同，而同一植物种群或功能群的年地上最大生物量出现的时间存在年际间的变化。采用当年最大地上生物量和8月30日固定日期的地上生物量作为群落ANPP的这两种方法高估了建群种或禾草功能群在群落中的作用。 羊草草原群落多年平均ANPPC1、ANPPC2和 ANPPC3分别是257.5、190.1和166.0 g.m-2;相应的大针茅草原多年平均ANPPC1、ANPPC2和 ANPPC3分别是180.4、132.8和122.5 g.m-2。就群落生产力而言，后两种常用的方法二和方法三分别低估了草原群落ANPP 14.2%～40.0%和15.5～59.0%。本文研究表明尽管ANPPC1与ANPPC2和ANPPC3之间存在显著的差异，但二者之间存在极显著的相关性:羊草草原的ANPPC1= 59.587+1.061×ANPPC2（r2＝0.865, p＜0.001），ANPPC1= 92.329+1.017×ANPPC3（r2＝0.569, p＜0.001）;大针茅草原的ANPPC1= 32.918+1.114×ANPPC2（r2＝0.814, p＜0.001），ANPPC1= 76.120+0.875×ANPPC3（r2＝0.499, p＝0.001）。 种群、功能群和群落地上净初级生产力与气候因子间的关系因不同的估测方法而异。羊草草原的建群种羊草种群仅ANPPS3与8月和11月份的平均温度间存在显著相关性，而大针茅草原群落的建群种大针茅种群的ANPPS1和ANPPS2与3月份平均最高气温间呈负相关关系。在羊草草原群落，杂类草功能群ANPPF1和ANPPF2与3月份气温呈负相关关系;而灌木半灌木功能群ANPPF1和ANPPF2与3月份降水呈负相关关系。在大针茅草原群落，禾草功能群ANPPF1与5月份最高平均气温呈显著负相关关系。羊草草原群落ANPPC1和ANPPC3分别与11月份最低温度和平均温度存在显著负相关关系;大针茅草原群落ANPPC1与2和6月份月降水量间相关性显著，ANPP2与5月和11月份月平均最低温度呈显著负相关关系，而4～9月份，1和4月份平均最低温度对群落ANPPC3起决定作用。 在羊草和大针茅草原群落，由方法一得到的群落水分利用效率、Shannon植物多样性指数和均匀度指数与方法二或方法三得到的相应的指数间存在显著的差异，方法二和方法三得到的值间差异不显著。群落地上净初级生产力与相应估测方法的植物Shannon多样性指数和均匀度指数之间相关性不显著。 放牧条件下羊草或大针茅草原群落中的建群种羊草和大针茅在群落中的相对地上生物量较围栏内的相应植物种群的降低，而糙隐子草种群在群落中的比例上升。不同的放牧管理条件下，群落中植物种群地上现存量的季节动态发生变化。群落的植物组成及植物种群地上生物量在群落中总生物量的比例发生了明显的变化。利用遥感来估测地上净初级生产力时，分别低估了羊草和大针茅草原ANPP 52％和27％。 DNDC模型可以很好地模拟内蒙古典型草原生态系统的地上生物量，通过敏感性分析表明降水是草原植物生长的主要限制因子，在降水量增加或降低至日降水的30%时，模拟的地上生物量显著地高于或低于实测地上生物量值。在多年平均降水量为347mm的情况下，随着土壤粘粒含量的增加，地上生物量逐渐降低，与北美草原一致。

Gaussian etched single transverse mode vertical-cavity surface-emitting laser

A continuous Gaussian profile matched to the fundamental mode was etched onto the aperture of a vertical cavity surface emitting laser (VCSEL). Single Gaussian spot emission was achieved over the entire operating current range.

The effect of dopants on the twist elastic constant and the rotational viscosity coefficient for nematics

The twist elastic constant, K2, and the rotational viscosity coefficient, γ1, are of importance when the response lime for the in-plane switching mode is studied. Since adding dopants is one technique to improve the response characteristics, the effect of dopants on these physical properties is significant. The effect on K2 and γ1 of adding alkyl(alkoxy) phenylcyclopentenones and alkyl(alkoxy) cyanobiphenyls to the base mixture ZLI-4792 together with their temperature dependence have been investigated using different temperature scales. The reduced temperature scale showed the effect of these dopants on K2 is small. On the other hand, the temperature dependence of γ1 depends on both the absolute temperature scale and the reduced temperature scale. Therefore, it is clear that the choice of temperature scale with which to compare γ1 for different systems raises fundamental questions which way not have a unique answer. 2000 OPA (Overseas Publishers Association) N.V. Published by license under the Gordon and Breach Science Publishers imprint.

大蹼铃蟾抗肿瘤蛋白及其制备方法和其基因

本发明涉及大蹼铃蟾抗肿瘤蛋白及其制备方法和其基因，属于生物医学领域。抗肿瘤蛋白是从中国两栖类动物大蹼铃蟾皮肤分泌物中分离得到的一种单链多肽，分子量2697，等电点9.83，多肽氨基酸全序列一级结构为：NH2－GIGGKILSGLKTALKGAAKELASTYLH－NH2。制备方法是收集大蹼铃蟾皮肤分泌物，离心去除沉淀、冷冻干燥后，经离子交换、高压液相反相柱层析分离纯化后得到。由650、623、625个核苷酸组成的三个不同的基因可编码大蹼铃蟾抗肿瘤蛋白，编码成熟抗肿瘤蛋白分别为第177－257位、第166－246位、175－255位核苷酸。具有抑制肿瘤细胞生长、抗艾滋病病毒活性和抑制细菌和真菌生长的作用。

Effect of thermal pollution on the hydrological parameters of River Jhelum (J & K)

The Buniyar hydroelectric project and the lower Jhelum Barrier at Gantamulla constructed across river Jhelum are in operation from several years. The two power stations have changed the hydrological features of the area where dam is situated. Therefore, the impact of hydroelectric projects on fishery resources of river Jhelum is a matter of great concern. The treated water from the power house is released through turbines, having cooling effect on them. The change in the hydrological parameters such as increase in temperature, depletion of oxygen etc. might have brought fishes under stress which is the main cause in decreased population of finfishes from site to site. The golden mahseer, Tor putitora which was once an abundant species in river Jhelum has disappeared due to human intervention. The prevailing water quality around hydroelectric projects is unsuitable for finfishes of river Jhelum.

Preservation of cotton fish net twines by tanning 1. Optimum concentration of tanning

Samples of tannin-containing preservatives used by fishermen in India for treating cotton nets were collected and qualitative and quantitative characterisation of the tannins made. The concentrations of different tannins required to impart optimum periods of preservation to the net were worked out and found to be 2% in 8 out of 10 materials studied.

Technological aspects of preservation and processing of edible shell fishes IV. Comparative efficiency of different glazes in the preservation of frozen crab meat

The present work was undertaken to enlighten upon the comparative efficiency of different glazes in improving the quality of frozen crab meat (Scylla Serrata).

Occurrence of enterotoxigenic staphylococci in frozen fishery products

Sixty six samples of frozen fishery products consisting of frozen crab meat, frozen prawns, frozen cuttlefish and frozen mussel collected from nine cold stores situated in and around Cochin city were examined for coagulase positive staphylococci. Forty eight samples (72.72%) revealed the presence of coagulase positive staphylococci, which were then tested for enterotoxigenity, employing cellophane-over-agar method for toxin production and optimum-sensitivity-plate (OSP) method for toxin detection. Seventy seven out of one hundred and two (75.49%) coagulase positive staphylococcal isolates from the above products produced enterotoxins A, B, C, D and E either singly or in combinations. Enterotoxin A and D were detected more often than others. The occurrence of enterotoxigenic staphylococci in frozen fishery product is reported for the first time in this country.

On the development of a mercury-free ternary aluminium anode for cathodic protection

The development of a new mercury-free ternary aluminum anode (CIFTAL) for cathodic protection of marine structures is described. The new anode demonstrated a current efficiency of 83.5% to 85.4% in a current density range of 5.6 to 166.7 mAdmˉ². The current efficiency remained practically stable at 1.4 mAdmˉ² over a test period of 300 days. The service trials of the anode on steel trawlers and aluminum (Indal M 57 S) sheathed wooden boats have shown satisfactory performance in terms of uniform dissolution, current efficiency and driving voltage. In the wake of legislations restricting the use of anodes containing mercury in an endeavor to control the mercury pollution of the near shore aquatic environment, the new anode (CIFTAL) with its stable current output and high current efficiency merits significance in marine cathodic protection.

Nucleotide variation and recombination along the fourth chromosome in Drosophila simulans

The fourth chromosome of Drosophila melanogaster and its sister species are believed to be nonrecombining and have been a model system for testing predictions of the effects of selection on linked, neutral variation. We recently examined nucleotide variat

Sex chromosomes in the black muntjac recapitulate incipient evolution of mammalian sex chromosomes

Background: The regular mammalian X and Y chromosomes diverged from each other at least 166 to 148 million years ago, leaving few traces of their early evolution, including degeneration of the Y chromosome and evolution of dosage compensation. Results: We

Study of physicochemical, microbial and sensory properties of surimi produced from black mouth croaker (Atrobucca nibe) at freezing condition (-18ºC)

Black mouth croaker (Atrobucca nibe) is considered as a new valuable fish stock in the Oman Sea. In this study, surimi was manufactured from nonmarket size of the fish, manually and different cryoprotectant agents were added to the surimi. Finally changes in physiochemical, microbiological and sensory quality, characteristics of the surimi and kamaboko gel samples were assessed during 6 months at freezing storage (-18ºC). Surimi samples with the addition of Iranian tragacanth gum (TG), xanthan gum (XG), chitosan (CS) and whey protein concentrate (WPC) at 1% (w/w) were prepared to evaluate their impacts as a cryoprotectant on the surimi, individually. The results showed that the whiteness and lightness indexes in all surimi samples were gradually decreased during frozen storage. This trend of decreasing was more intensity in the control sample from 61.08±0.131 to 54.21±0.067 was recorded (p<0.05). Water holding capacity (WHC) in all treatments was decreased during 6 months. The lowest WHC (g/g) was obtained in the surimi without cryoprotectants and maximum WHC was measured in Tcs and Twpc samples, respectively (p<0.05). The lowest breaking force was calculated in Txg (166.00±22.627 g) and Tc (271.50±263.16 g) during 6 months at frozen storage, respectively (p<0.05), while Twpc treatment with slight variations showed the highest breaking force (p<0.05). Also, the lowest gel strength was obtained in Txg (68.22±6.740 g.cm) after 6 month of frozen storage (p<0.05). All Kamaboko surimi gels texture profile analysis parameters decreaced with increasing shelf life. This decreasing trend in the control sample was more severe. Floding results were reduced in all samples during storage (p<0.05). The best protective results probably were obtained in WPC, chitosan and commercial cryoprotectant agents, respectively due to protein stabilization of myofibrillar proteins and the protein-protein network structure, leading to the formation of surimi gel with strong textural properties during frozen conditions. The average number of surimi polygonal structures were significantly decreased (number per mm2) and their area were significantly increased (μm2) in all treatments (p<0.05). With increasing storage time, moisture, protein contents and pH were decreaced. Maximun TVB-N index was calculated in Tc (7.93±0.400 mg/100g) and Txg (7.88±0.477), respectively (p<0.05). TBRAs index was increased in all treatments during frozen storage, while this trend was reached in maximum value in Tc (p<0.05). Sensory evaluation of the fish finger quality characteristics (color, odor, texture and overall acceptability) preapare from frozen black mouth croaker surimi was decreaced during 6 month frozen storage. After the period of frozen storage the highest quality scores were measured in Twpc, Tcs and Tcc samples, respectively (p<0.05). In this study, coliform bacteria were not found in all treatments during frozen storage. The surimi sample containing chitosan showed lower mesophilic and psychrotropic bacteria (log cfu/g) than other treatments during frozen storage (p<0.05). Salt-soluble proteins extractions of all treatments were decreased during frozen storage. This decreacing trend was highest in Tcs (45.74±0.176%) and lowest in Tc treatments after 6 month of frozen storage (29.92±0.224%) (p<0.05). Although commercial cryoprotectant agents were successful in limiting the denaturation of proteins but sugar contents were not accepted for diabetics or those who disagree with the sweet taste and high calorie food. Hence, commercial cryoprotectant agents can be replaced with whey protein concentrate and chitosan at 1% level (w/w) consider that they were showed proper protection of the surimi myofibrillar proteins during storage.