首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   21篇
  免费   0篇
  国内免费   1篇
  2013年   1篇
  2011年   2篇
  2010年   1篇
  2009年   1篇
  2008年   2篇
  2007年   2篇
  2006年   2篇
  2005年   2篇
  2003年   1篇
  2002年   1篇
  2001年   1篇
  2000年   1篇
  1999年   1篇
  1998年   1篇
  1992年   1篇
  1989年   1篇
  1986年   1篇
排序方式: 共有22条查询结果,搜索用时 645 毫秒
1.
洪湖子莲开花结实习性及调控技术的研究   总被引:3,自引:1,他引:2  
阐明了子莲开花结实习性与花期气候的关系,并以洪湖气候与子莲开花结实的关系,莲蓬大小和莲蓬心皮数目与荷花发育时所处季节地关系以及死蕾,死花,死果与开花时天气的关系等三方面,论证了在该区调控子莲开花结实的必要性。最后还提出了调控子莲开花结实的几项农业技术。  相似文献   
2.
This study tested the hypothesis that a habit reversal program emphasizing awareness and reduction of masticatory muscle activity would significantly reduce pain in patients diagnosed with chronic temporomandibular disorder (TMD) and would be a competitive alternative to a behaviorally-modified dental intervention. Eight individuals diagnosed with TMD were randomly assigned to a splint therapy or habit reversal group. Patients in the splint group received an interocclusal appliance (splint) fabricated from acrylic and were instructed to wear the splint day and night up to a maximum of 20 h per day. Patients in the habit reversal group were given a pager and instructed to check tooth position and masticatory muscle tension when paged. Paging occurred approximately once every 2 h during the day, but not at night. Both groups were instructed to avoid tooth contact and relax the masticatory muscles during the 4 weeks of active treatment. Outcome data were collected at 1 month and 1 year post-treatment intervals. Pain decreased significantly for both groups and did not differ between groups. Habit reversal may be as effective as a behaviorally-modified splint therapy for TMD-related pain.  相似文献   
3.
The biomineralization of otoliths results mainly from the release of soluble Ca(2+), which is in turn precipitated as CaCO(3) crystals. In some Carapidae, sagittae sections have been shown to reveal a three-dimensional asymmetry with a nucleus close to the sulcal side, an unusual position. This study seeks to understand otolith formation in Carapus boraborensis. The unusual shape of the otolith is partly explained by the distribution of the epithelium cells, and particularly the sensory epithelium. Experimental evidence shows for the first time that aragonite growth takes place along the c-axis. These aragonite needles present two different habits. On the sulcal side is found the acicular form resulting from rapid growth during a short period of time. On the anti-sulcal side, the prismatic form seen there is due to a slower growth speed over longer periods. The otolith surface was observed each hour during a period of 24h in fishes reared in similar conditions. This allowed for the first time the direct observation on the otolith surface of the deposition of the two layers (L-zone and D-zone). In C. boraborensis, the organic-rich layer (D-zone) develops during the day, whereas the CaCO(3) layer (L-zone) seems to be deposited during the night.  相似文献   
4.
地花菌属(Albatrellus Gray)是多孔菌类中具有突出特征和特殊地位的一个属,有极高的系统学和分类学研究价值,但专门的针对性研究很少。综述了地花菌属在分类学、系统学、牛态习性、经济价值、保护生物学等方面的研究概况和进展,并对该属的深入研究提出了针对性的建议。  相似文献   
5.
鲎的分布及生活习性   总被引:6,自引:1,他引:6  
鲎是一种古老的节肢动物,现存的鲎分为二亚科三属四种,本文对鲎在世界上的分布及其生活习性做了概述。  相似文献   
6.
Synopsis Foraging butterflyfishes follow predictable paths as they swim from one food patch to another within their territories and home ranges. The pattern is repeated throughout the day. The behavior is described in species belonging to the coral feeding guild. Habit formation and spatial learning are implicated. Foraging paths are based on learned locations of route specific landmarks. When a coral head is removed the fish look for it in its former location. If pairs of foraging fish are deflected from the path, they resume their routine pattern at the first landmark they encounter. Periodically, fish make excursions of 30 m or more to distant parts of the reef. Usually they follow different paths on the outbound and homeward legs of these excursions. The critical question is: Are the paths novel? If they are, it is evidence for the use of cognitive maps. Certainly fishes living in the highly structured coral reef environment are prime candidates to use cognitive maps in their orientation behavior.  相似文献   
7.
Researchers have hypothesized that habitual behaviors are zeitgebers for the circadian clock. However, few studies have examined the relationship between habitual behaviors and light, the strongest zeitgeber. Depression is an ideal model in which to explore this relationship because depression is a disorder associated with disruptions in circadian biological activity, sleep, and social rhythms (or patterns of habitual behaviors). We hypothesized that individuals with fewer habitual behaviors have less average exposure to light from morning rise time to evening bedtime and that a reduction in light exposure increases the likelihood of depression. Thirty-nine depressed and 39 never-depressed participants wore an ambulatory light monitor and completed the Social Rhythm Metric over the course of 2 weeks. Linear and logistic regression techniques were used to calculate regression coefficients, and confidence limits based on the distribution of the product of two normal random variables were computed to test the significance of the mediation effect. Infrequent habitual behaviors were associated with a decrease in average levels of light exposure, and low levels of light increased the likelihood of depression. This mediation effect was partial; the overall number of habitual behaviors had a direct relationship with depression above and beyond the association with light exposure. Longitudinal studies are needed to empirically demonstrate the direction of relationships between each of the variables tested.  相似文献   
8.
高原鼢鼠食性的研究   总被引:7,自引:2,他引:5  
在高寒草甸和高寒灌丛两种栖息地中捕获高原鼢鼠 1 44只 ,将 92只鼢鼠的胃内容物对照已知植物组织的显微结构进行分析 ,以确定其食物组成。研究结果表明 ,虽然两种栖息地之间的植被组成有极大的差异 ,但是高原鼢鼠的食物组成在两种栖息地之间和性别之间均无明显的不同 ,不同植物出现的频次却有明显的差异。禾本科植物在高原鼢鼠的胃内容物中基本没有发现 ,对莎草科植物也只取食两个物种 ,高原鼢鼠所取食的植物主要是杂类草。在两种栖息地中高原鼢鼠喜食度指数最高的 9种植物均为鹅绒委陵菜、直立梗唐松草、丽江风毛菊、雪白委陵菜、美丽风毛菊、细叶亚菊、异叶米口袋、磨岭草和棘豆。  相似文献   
9.
云南思茅亚洲象对栖息地的选择与利用   总被引:9,自引:3,他引:6  
张立  王宁  王宇宁  马利超 《兽类学报》2003,23(3):185-192
以思茅市境内栖居的一个由5 头雌象(3 头成年体, 1 头亚成体, 1 头幼体) 组成的象群为研究对象, 利用痕迹追踪、样线调查和村庄调查等方法对野生亚洲象的栖息地选择和行为进行了初步研究。在栖息地中共记录到野生高等植物457 种, 组成5 种植被类型。旱季象群的活动区域面积是35.67 km2 , 该活动区域中有3 个核心活动区, 面积分别是3.65 km2 , 2.79 km2 和3.29 km2 , 象群对此3 个活动核心区域循环利用; 在旱季亚洲象经常取食19种野生植物, 其中主要取食的有8 种, 还取食7 种农作物, 对农作物有一定依赖性, 这种依赖的程度随着农田周围森林中野生食物丰富程度的增加而降低; 在季雨林中亚洲象主要取食的植物种类最丰富。雨季象群的活动区域面积是18.42 km2 , 该区域中只有1 个核心活动区, 面积9.08 km2 。雨季亚洲象只取食5 种野生植物, 另取食5 种农作物, 农作物为其雨季主要食物。研究结果表明, 思茅地区亚洲象栖息地中的野生食物可能不足, 人类活动对亚洲象的生存干扰较为严重, 亚洲象的行为表现出对栖息地内食物条件和人类干扰的适应。建议尽快遏止日益严重的栖息地片断化趋势, 恢复自然植被并为亚洲象提供充足的野生食物是保护该物种的关键。  相似文献   
10.
This study investigated both laboratory-reared and pond-cultured subjects to explore the habit and hibernation patterns of the sea slug Onchidium struma (Mollusca, Gastropoda, Systellommatophora, Onchidioidea, Onchidiidae) from Shanghai and Zhejiang in China. Movement and feeding habits and the process of hibernation were observed in culturing tanks from June 2004 to March 2008. Our results showed that the conditions of movement are as follows: a minimum air temperature of 12 °C; a maximum light intensity of 25 lux and a minimum relative air humidity of 72%. Major movement is usually at dusk and during the night, and the average temperatures for fasting and beginning hibernation are 13.8 °C and 11.4 °C respectively. The analysis showed that the temperature is an essential factor affecting movement and feeding of O. struma and that RH and light intensity also play an important role, but are not necessarily required at the same time. In this study, the survival rate of O. struma through hibernation in high-biodiversity culturing tanks is 77.57% ± 2.86%.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号