北京白癜风最好的医院Abstract With the accelerated development of education， a large number of doctoral and master"s theses e out each year， which involve the fields of advanced technology， national economy and people"s livelihood. Academic dissertations collection in our country is not prehensive， database separated， and copyright not clear， resulting in restricted dissertation circulation and low citations rate. Meanwhile， directors and their students have poor awareness of security management. Irregular management in classified dissertations and lack of monitoring management process increase the potential risks of dissertations"security. Based on the analysis the experiences of openness， utilization， and safety management of dissertation at abroad， the author proposes to increase the development and utilization of the dissertation from the perspective of safety management. National dissertation presentation mechanism can be established and improved in which dissertation copyright can be bined into a unified national dissertation database， and the dissertation retrieval service platform can be built； we should build a safety management system of classified dissertation， standardize the dissertation range and classification of the review， enhance the supervision of dissertation process， block the hidden danger of the leakage of a dissertation secrets， promote the dissertation circulation， display the potential value of national dissertation， and provide intellectual support for technology and social development in our country.
鸡冠花叶子上出现粉红色霉层是由叶斑粉腐病侵染引起的。发病初期，叶上产生褐色小斑，后逐渐扩大成为圆形、椭圆形或不规则的大病斑，中央浅褐色，边缘深褐色，并有不明显的轮纹。后期病部密生粉红色霉层。发病严重时，植株大量枯死。鸡冠花叶斑粉腐病还可侵染鸡冠花的叶柄、茎，使茎上产生暗褐色病斑进而腐烂。植株从病患处倒伏，茎叶凋萎枯死。 鸡冠花叶斑粉腐病的病原真菌是镰刀菌属的一种，常存在于土壤中，在病残植物体上越冬。鸡冠花的种子也能携带病菌并传播。在高温高湿、阴雨连绵的季节发病严重。 鸡冠花叶斑粉腐病的防治措施：一是加强栽培管理，发现病株及时拔除，并用l％福尔马林进行土壤消*。二是严格从无病株上采种。采种母株应隔离栽培，并喷50％克菌丹500倍液或40％多菌灵悬浮剂500倍液加以保护。种子播种前，用40％多菌灵悬浮剂500倍液浸泡4小时，也有利于防病。 另外，鸡冠花叶上病斑类型很多，如褐斑病、黑斑病、炭疽病等。可参照叶斑粉腐病的防治方法进行防治。
