Results 31 to 40 of about 1,050 (155)
, 2004 从N 乙基壳聚糖的35%(重量百分比)甲酸溶液浇铸膜制备片状单晶.单晶呈矩形,最大单晶长度达800μm.片状单晶生长在球晶微纤的顶端或没有球晶的地方.片状单晶中分子链方向取矩形的长边方向.单晶中裂纹的方向也是这一方向.由于浇铸膜吸潮,形成片状单晶的实际高分子浓度为83%左右,在此浓溶液中结晶非常缓慢 ...
毕丹霞 +4 more
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Biodiversity‐driven spatial conservation planning to delineate temporally stable regions
Conservation Biology, EarlyView.Abstract The accelerating loss of biodiversity underscores the critical need for effective conservation strategies, particularly in the face of climate change and anthropogenic pressures. We devised a conservation planning framework that adopts a temporal stacking approach to species distribution models and landscape connectivity analyses. These models
Mattia Iannella +5 more
wiley +1 more source
, 1996 用偏光显微术、平均折射率法和富立叶红外光谱法研究了壳聚糖的溶致液晶行为。在二氯乙酸、甲酸、丙烯酸和３６％乙酸等溶剂中测得的临界浓度都是８％（体积比）或４％～６％（重量比），与根据Ｆｌｏｒｙ理论得到的计算值相符 ...
张璟, 董炎明
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Evaluating synthetic substitutes to reduce illegal harvesting and support species recovery
Conservation Biology, EarlyView.Abstract Providing synthetic substitutes is a widely promoted strategy to shift consumer demand away from wildlife products derived from threatened species. Yet, there is little evidence on whether product substitution prevents illegal or unsustainable harvesting and contributes to the recovery of threatened populations.
Aditya Shekhar Malgaonkar +17 more
wiley +1 more source
, 2011 通过圆环试验,研究了4种常用减水剂和UEA膨胀剂对混凝土收缩开裂的影响。结果发现:聚羧酸系和萘系高效减水剂对净浆开裂龄期均有延缓作用,但影响规律却不尽相同。随着聚羧酸系减水剂掺量的增多,试件开裂龄期逐渐缩短,抗裂性能下降;而随着萘系减水剂掺量的增多,试件开裂龄期逐渐增长,抗裂性能提高。UEA膨胀剂在6%～12%范围的等量内掺 ...
余彬彬, 刘冬冬, 胡红梅
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Informal supply chains of wild meat from rural Amazonia and food security in an urban center
Conservation Biology, EarlyView.Abstract Iquitos, the most populated city in the Peruvian Amazon, is a hub in the regional supply chain of wild meat and supplies urban consumers. Studies on wild meat consumption have focused primarily on markets, limiting the scope of species considered to those that are economically valuable and potential inferences from those data.
Fiorella Briceño Huerta +3 more
wiley +1 more source
Design of Automatic System for Measuring Dielectric Properties of Microwave Dielectric Ceramics [PDF]
, 2008 开路型微波陶瓷材料介电性能自动测试系统的设计包括系统的测试原理、系统硬件和软件组成。利用操作界面友好的自动测试程序,可在程序面板上控制网络分析仪,实现测试数据的实时采集、分析计算与显示存储,从而提高测试效率与精度。实测表明,利用该系统能对高介电常数、低损耗的微波陶瓷材料复介电常数进行快速、准确、无损的自动测试。Design of open automatic system for measuring dielectric properties of Microwave Dielectric ...
李秀燕, 肖芬, 陈赐海
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Assessing differences among elasmobranch nurseries to aid conservation based on a genomics framework
Conservation Biology, EarlyView.Abstract Elasmobranch nurseries often differ in environmental conditions, demographics, and use patterns. These differences affect the distribution of genetic variation among nurseries. However, conservation and management strategies often fail to account for such differences because they are difficult to characterize.
Dominic G. Swift +8 more
wiley +1 more source
半刚性钢框架-冷弯薄壁型钢填充复合墙板结构的计算模型及时程分析
Jianzhu Gangjiegou Jinzhan, 2021 为推广冷弯薄壁型钢填充复合墙板在高层结构中的应用,进一步了解该冷弯薄壁型钢填充复合墙板作为抗侧力构件应用于高层结构中的抗震性能,将冷弯薄壁型钢填充复合墙板引入半刚性钢框架结构中并研究其抗震性能。基于有限元分析软件SAP2000,采用Pivot恢复力模型对冷弯薄壁型钢填充复合墙板进行简化分析,并推导出墙板P-Δ骨架曲线关系公式;采用转角弹簧单元对矩形钢管柱与H形钢梁单边高强螺栓连接节点进行简化分析;并在此基础上建立半刚性钢框架-冷弯薄壁型钢填充复合墙板结构简化分析模型。在此简化基础上 ...
王静峰 +4 more
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Analysis on the Elastic Lateral Stiffness under Seismic Action for Palace Structure in the Building Standards of Song Dynasty [PDF]
, 2015 中国古代木构架房屋具有良好的抗震性能，其中凝结了长达数千年间古代的建筑工程经验与智慧。这种“干架”结构有别于现代刚接杆系结构，其结构受力分析尚不能直接套用现代框架结构计算方法。已有的研究，通过缩尺模型试验，回归分析，拟合出类似于现代钢筋混凝土框架结构的动力学方程，尚未能揭示出符合古代设计思想及技术水平的基本原理。从古代房屋结构的设计、建造方法入手，探寻其本源的科学原理，一方面可以为古代建筑的安全性能评价找到一般性的方法，另一方面，古为今用，可以为现代工程建设带来新的启迪。 本文在深入研读《营造法式 ...
黄燕萍
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