越来越苍老的世界

中国全面推行计划生育政策,少生了3亿多人,节约了7万亿抚养费,也少了3亿可以负担养老的劳动力。由于老龄化加速,老年抚养比由1964年的6.4%上升为2002年的11.6%,离退休金平均实际递增18.9%。到2050年,中国的抚养比将可能达到70%。老龄化速度,法国用了115年,英国用了80年,美国用了60年,我国用了18年。     

远程教育培训给生物教学带来新的生机

远程教育培训给生物教学带来新的生机。夯实了专业知识,梳理了生物知识,使我认识到应该如何把握生物课堂教学,提高了课堂教学设计能力,凝聚了生物教师的力量,使老师们学到了很多知识和教学技能,解决了平时教学中的一些难题,提升了生物的教学水平。     

亚热带丘陵茶园间作白三叶的土壤环境调控效果

在亚热带丘陵区1年生幼龄茶园通过连续4年间作白三叶大田试验,研究了其对茶园土壤环境及茶叶品质、产量的影响,结果表明,茶园间作白三叶降低了土壤容重,提高了土壤孔隙度、有机质、全氮、水解氮的含量及钾的活性,消耗了部分有效磷;增加了土壤关键层次（0～20cm）和关键时期（4～6月）的水分含量,延缓和缩短了夏季高温干旱与秋季持续干旱时间;获得了土壤降温时增温、保温与升温时降温的双向动态调控效果．增加了同一层次土壤温度的稳定性,延缓了高温和低温的出现时间,缩短了过度高温时间。从而促进了茶树生长,改善了茶叶品质,显著增加了茶叶产量。与清耕茶园相比,茶园间作白三叶后,春秋茶的酚氨比分别下降了17．10％和30．90％,产量提高了32.65％。     

酷想大晒台

哎呀呀,这个世界乱套了!大人变成了小孩,小孩变成了大人。现在,终于轮到各位小酷想家来当家做主了,快来看看他们都有什么出色的表现吧!看到爸妈变成了小孩,我立马学着他们的样子,下达了第一道命令:写作业去!我想他们一定会哭的,因为老师留的作业实在是太多了。新浪YOYO     

砷对烤烟(Nicotiana tabacum L.)碳代谢的影响

采用盆栽试验,系统地研究了砷对烤烟全生育期碳代谢及其过程的影响,结果表明,砷降低了烤烟整个生育期的叶绿素含量、光合速率、蔗糖合成酶（SS,合成方向）活性和现蕾以后的蔗糖磷酸合成酶（SPS）活性,提高了全生育期的SS（分解方向）活性和可溶性糖含量,因而抑制了碳的同化和蔗糖的合成,促进了蔗糖的分解,不利于碳向积累方向转化。砷提高了全生育期的腺苷二磷酸葡萄糖焦磷酸化酶（ADPG-PPase）活性,增加了团棵期和现蕾期淀粉的积累,降低了团棵期和采收期的可溶性淀粉酶（SSS）活性和采收期的淀粉含量,从而导致了碳积累代谢的紊乱,最终造成碳积累的减少。     

一年又一年

上了年纪的人都有相似的感觉,就是年纪越大,时间好像过得越快。小时候,过了元旦盼春节,过了春节盼五一、六一,过了六一盼国庆,过了国庆再盼元旦。时间总是那么漫长,盼望的假期似乎总是姗姗来迟。而如今,似乎一眨眼,一年就过去了。我给这个现象总结了一个理论,叫做相对     

生态条件的多样性变化对蜜蜂生存的影响

蜜蜂在整个生态系统中起着重要的传花授粉作用,是生态链中不可或缺的物种。随着现代农业的发展,蜜蜂赖以生存的环境遭到破坏,继而引发蜜蜂数量大幅减少,影响了蜂种的生存与可持续发展。总结了近年来生态条件的变化,归纳了影响蜜蜂生存的主要因素,分析了蜜蜂生存艰难的原因,提出了蜜蜂生存的关键问题,并展望了未来维持蜜蜂强群的主要研究方向。     

中国农业生物技术发展概况

当前在世界范围内由于人口的迅速增长导致的粮食危机正日益为各国科学家和政治家所关注。中国既是一个人口大国、也是个农业大国。半个世纪以来,特别是近十年来,在坚持四项基本原则和改革开放的方针指引下,我们以占世界7％的耕地养活了占世界近22％的人口,基本解决了温饱问题,并且提供了较充足的工业原料,取得了瞩目的成就。1984年后,虽然粮食产量出现了徘徊形势,但1989年,粮食产量有较大回升,达到了40475万吨,超过了1984     

转基因鸡的制备方法探讨

由于鸡本身的众多优点,转基因鸡的研究逐渐受到了研究者的重视,简要介绍了转基因鸡的发展史,对各种转基因技术方法进行了比较和分析,提出了每种方法的优缺点,尤其在精子介导法上作了较为详细的论述,并展望了转基因鸡的应用前景。     

促进微生物实验技术创新水平的改革初探

为了加强对本科生综合素质和能力的培养 ,激发学生的学习兴趣 ,我们对微生物实验课的教学内容进行了一系列改革 ,优化了实验项目 ,节约实验成本 ,并且引入科研成果转化实验 ,同时改进了实验方法和手段 ,实验结果更为准确。这些措施蕴含了较高的理论水平 ,增加了教学信息量 ,明显提高了教学效果 ,为培养高素质人才奠定了基础。     

Materials for Chinese Phyllanthoideae

The present paper is part of taxonomic study on Chinese Phyllanthoideae. Included in it are two new varieties, Leptopus esquirolii var. villosus and Drypetes hainanensis var. longistipitata, one new combination, Glochidion triandrum var. siamense, and seven new records in China: Drypetes salicifolia, D. hoaensis. Actephila subsessilis, Glochidion khasicum, G. nubigennum, Bridelia spiosa and B. poilanei. In addition, seventeen taxon names are newly reduced: Liodendron formosanum = Drypetes formosana, Liodendron matsumurae = Drypetes matsumurae, D. longipes = D. indica, Antidesma paxii = A. acidum, A. hiiranense, A. filipes and A. pentandrum var. hiiranense = A. japonicum, A. calvescens = A. montanum, A. microphyllum = A. venosum, Breynia stipitata var. formosana and B. jormosana = B. vitis-idaea, Glochidion zeylanicum var. tomentosum = G. hirsutum, G. rubidulum = G. thomsonii, G. acuminatum = G. triandrum, G. fagifolium and Phyllanthus fagifolius = Glochidion sphaerogynum, Bridelia penangiena = B. insulana, B. henryana = B. tomentosa. All the types are kept in SCBl and PE.     

Phylogenetic revision of the Taenogera Kröber genus-group (Diptera: Therevidae), with descriptions of two new genera

The phylogenetic relationships of the Taenogera genus-group, consisting of nine genera, are examined using cladistic methods. Twenty-one species representing nine genera and one outgroup were compared in a cladistic analysis across 99 states in 44 characters. The genus Taenogera Kröber is revised to contain only T. longa (Schiner), T. nitida (Macquart) and T. notatithorax Mann. Two new genera are described and figured: Actenomeros gen. n., with two species, A. corniculaticaudus sp. n. and A. onyx sp. n.; and Taenogerella gen. n., with four species, Ta. elizabethae sp. n., Ta. platina sp. n., Ta. schlingeri sp. n. and Ta . nigrapicalis (Mann) comb. n. Phylogenetic analysis also supports the removal of Nanexila gracilis (Mann) comb. n. from Taenogera .     

Relationships between host blood factors and proteases in Glossina morsitans subspecies infected with Trypanosoma congolense

Abstract. Host blood effects on Trypanosoma congolense establishment in Glossina morsitans morsitans and Glossina morsitans centralis were investigated using goat, rabbit, cow and rhinoceros blood. Meals containing goat erythrocytes facilitated infection in G. m. morsitans , whereas meals containing goat plasma facilitated infection in G. m. centralis. Goat blood effects were not observed in the presence of complementary rabbit blood components. N-acetyl-glucosamine (a midguMectin inhibitor) increased infection rates in some, but not all, blood manipulations. Cholesterol increased infection rates in G. m. centralis only. Both compounds together added to cow blood produced superinfection in G. m. centralis , but not in G. m. morsitans. Midgut protease levels did not differ 6 days post-infection in flies maintaining infections versus flies clearing infections. Protease levels were weakly correlated with patterns of infection, but only in G. m. morsitans. These results suggest that physiological mechanisms responsible for variation in infection rates are only superficially similar in these closely-related tsetse.     

Selection of Verticillium lecanii Isolates with High Potential for Biocontrol of Cucumber Powdery Mildew by Means of Components Analysis at Different Humidity Regimes

To identify characteristics for the selection of Verticillium lecanii isolates with high potential for biocontrol of Sphaerotheca fuliginea under glasshouse conditions, an exploratory study was performed on the effect of water limitation on the development of 14 isolates. The conidial germination, growth and sporulation of isolates of V. lecanii were studied in a tritrophic system on cucumber leaves and in a ditrophic system in Petri dishes. Their mycoparasitic ability was studied in S. fuliginea and Cladosporium cladosporioides . All characteristics were clearly affected by humidity. Four isolates showed good biocontrol potential. The performance of isolates on agar had less predictive value than on powdery mildew. The germination of isolates of V. lecanii was lower and the mycelial growth faster on agar than on mildewed leaves under corresponding humidity conditions. The results suggest that conditions in the phyllosphere differed from the set humidity in the surrounding air. A correlation was found between the lysis of C. cladosporioides growing in dual culture on agar with isolates of V. lecanii and the parasitism of powdery mildew on detached, rooted leaves. C. cladosporioides might offer a suitable substrate for testing isolates of V. lecanii for mycoparasitic potential under various environmental conditions. Conidial germination, growth and sporulation had limited predictive value.     

Evaluation of the Palaearctic Eurithia consobrina (Diptera: Tachinidae) as a Potential Biocontrol Agent for Mamestra configurata (Lepidoptera: Noctuidae) in Canada

The evaluation of Eurithia consobrina (Meigen) as a candidate for introduction against bertha armyworm, Mamestra configurata (Walker) (Lepidoptera: Noctuidae), in western Canada included studies of its host range, distribution, synchronization with host, constancy, abundance and life history in Europe. In addition, its diapause induction and its coldhardiness were compared with those of the target host M. configurata and its native tachinid parasitoid, Athrycia cinerea (Coq.). E. consobrina was found to fit criteria for a successful biocontrol agent reasonably well. It also had the potential to fill a largely unoccupied niche in the parasitoid complex of M. configurata. E. consobrina has a facultative diapause of the long-day type, similar to A. cinerea, but is less sensitive to diapause-inducing conditions. E. consobrina is at least as coldhardy as A. cinerea and more coldhardy than M. configurata. Laboratory exposures to temperatures of 0 C for 140 days apparently selected for greater coldhardiness, and later generations survived exposures of 140 days at -15 C without significant mortality. Adult E. consobrina were released at three locations in Manitoba in 1986 and 1987, but establishment has not been confirmed.     

Predation by Halmus chalybeus (Coleoptera: Coccinellidae) on Ceroplastes destructor and C. sinensis (Hemiptera: Coccidae: Ceroplastinae) Infesting Citrus in Northland, New Zealand

Predation by Halmus chalybeus (steelblue ladybird) on two species of wax scale was studied on citrus orchards in Northland, New Zealand. Field experiments using an exclusion technique of enclosing citrus branches in bags, found that larval and adult H. chalybeus preyed on first and second instars of both Ceroplastes destructor (white wax scale) and C. sinensis (Chinese wax scale), but not third instar C. destructor. Third instar C. sinensis and adults of both species were not tested but are rarely, if ever, attacked by H. chalybeus. The sampling of scale and ladybird populations and field experiments showed that few scales of either species survived past the second instar stage where H. chalybeus was numerous. The feeding rate of H. chalybeus on settled first and second instar scales was estimated inside bagged branches. Adults consumed on average 15.6 C. destructor and 13.3 C. sinensis per day per ladybird, while larvae ate 9.7 C. destructor per day. These feeding rates accounted for the experimental reduction of scale populations. H. chalybeus is a useful natural enemy for the control of C. destructor and C. sinensis when its activity is not disrupted by pesticides.     

Further flavonoid studies onAttalea species and some related cocosoid palms

In a flavonoid survey of direct and hydrolysed leaf extracts of sixteenAttalea, sevenScheelea and fourOrbignya species free tricin, tricin 7-glycosides, tricin 5-glucoside and flavone C-glycosides were the most frequent constituents; present in 100, 89, 70, and 81% of species, respectively. Luteolin, quercetin and isorhamnetin were each found in only 15% of the sample. The present results confirm the findings of a previous survey thatAttalea, Scheelea andOrbignya are chemically heterogeneous with as much variation between species as between genera. Furthermore, threeAttalea species,A. allenii, A. guaranitica andA. victoriana showed some infraspecific variation. On the other hand all three accessions ofA. ferruginea and six ofA. geraensis examined gave identical flavonoid profiles. The results support the view thatA. geraensis andA. guaranitica are closely related but do not support the suggested close relationship based on morphology betweenA. oleifera, A. burretiana andA. piassabossu.     

Investigations into the evolutionary history of the polyploid complexAntennaria neodioica (Asteraceae: Inuleae)

TheAntennaria neodioica polyploid agamic complex is a polymorphic species occurring across North America mainly north of the terminal margin of the Wisconsin glacier. This taxonomically difficult group has recently been treated as consisting of the four subspeciesA. neodioica subsp.canadensis, subsp.howellii, subsp.neodioica, and subsp.petaloidea. TheA. neodioica agamic complex has been considered of hybrid origin with several sexual diploid species constituting its parentage. Crosses were made among five sexual diploid species ofAntennaria, morphologically similar toA. neodioica s.l., in an attempt to discover its origins. Representative specimens of the five diploid species,A. neodioica s. l., and the synthetic interspecific F₁ hybrids were subjected to various analyses including PCA, cluster (UPGMA), and discriminant analyses. Results suggest that theA. neodioica complex is of multiple hybrid origin involving the four diploid speciesA. neglecta, A. plantaginifolia, A. racemosa, andA. virginica. BecauseA. neodioica is the result of diverse origin it is more desirable to consider the agamic complex as a separate, distinct species from its sexual diploid relatives. Several morphological characters in the diploid species were determined to be polygenically inherited.Investigations into the Evolutionary History of the Polyploid Complexes inAntennaria (Asteraceae: Inuleae). I.