全文获取类型
收费全文 | 134篇 |
免费 | 10篇 |
国内免费 | 16篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 5篇 |
2020年 | 9篇 |
2019年 | 13篇 |
2018年 | 10篇 |
2017年 | 4篇 |
2016年 | 13篇 |
2015年 | 8篇 |
2014年 | 8篇 |
2013年 | 10篇 |
2012年 | 8篇 |
2011年 | 12篇 |
2010年 | 4篇 |
2009年 | 4篇 |
2008年 | 6篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 1篇 |
2003年 | 3篇 |
2002年 | 7篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1996年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1989年 | 2篇 |
1987年 | 1篇 |
排序方式: 共有160条查询结果,搜索用时 15 毫秒
1.
采用内置记录活动水平传感器的GPS项圈研究了卧龙自然保护区3只野生大熊猫春季取食竹笋期间的昼夜活动节律和强度,并分析了太阳辐射、温度因子对大熊猫活动节律与强度的影响。3只大熊猫的平均活动率为68.05%,受孕雌性大熊猫的活动率(70.86%)和活动强度(范围:0-255;水平方向/垂直方向,23.82±0.30/ 17.63±0.22)均比其它两只大熊猫(70.55%, 14.71±0.17/13.52±0.15 ;62.76%,17.74±0.23/13.61±0.18)高。大熊猫有3次活动高峰,分别出现在6:00-7:00,18:00-21:00和23:00-3:00,一个明显的活动低谷,出现在9:00-12:00。大熊猫白天的活动率(68.32%)和活动强度(19.59±0.20/ 15.45±0.15)比夜间(67.67%,17.63±0.19/14.21±0.15)高。大熊猫的活动强度与太阳辐射之间存在显著负相关(r=-0.822, P<0.001),与空气温度之间不存在显著的相关性。 相似文献
2.
保护区内放牧活动对野生动物保护存在负面影响,明确不同物种对放牧干扰的行为响应对制定更有针对性的保护管理政策具有重要意义。使用红外相机研究卧龙自然保护区放牧活动对多种珍稀野生动物的影响,分析放牧激励政策实施前后大熊猫(Ailuropoda melanoleuca)及其同域分布的小熊猫(Ailurus fulgens)、川金丝猴(Rhinopithecus roxellana)、水鹿(Rusa unicolor) 4种珍稀野生动物的照片数、空间分布以及活动模式的变化,探讨这4种动物对放牧的行为响应策略。结果表明:(1)一期(2012—2013),2012年10月实施了禁马政策,同年12月实施放牧(牛羊)激励政策)家畜照片数量很少,4种野生动物照片数相对较多。二期(2014—2015)家畜的照片数显著增加(P0.01),小熊猫(P0.05)与川金丝猴(P0.01)的照片数均显著减少,大熊猫、水鹿的照片数也呈减少趋势;到三期(2016—2017),大熊猫、小熊猫及水鹿3种关注野生动物的照片数基本回升到激励政策实施前的水平,无川金丝猴照片记录。(2)一期,4种野生动物在研究区域有较广的分布;二期,大熊猫、小熊猫的空间分布范围均缩小,无川金丝猴空间分布信息,而家畜、水鹿的空间分布范围有所增加;到三期,大熊猫、小熊猫的空间分布基本恢复到放牧激励政策实施前的区域,无川金丝猴的空间分布信息。(3)放牧激励政策实施前后,大熊猫、小熊猫及川金丝猴活动模式无明显变化,但水鹿的活动更加集中于傍晚,以避开人类与家畜的活动高峰。同域分布的不同的野生动物对人类活动(如放牧)的行为响应策略不同,各保护区在制定相关保护政策时应综合考虑人类干扰对多个物种的影响,增加决策的科学性与合理性。 相似文献
3.
4.
Jindong Zhang Vanessa Hull Zhiyun Ouyang Liang He Thomas Connor Hongbo Yang Jinyan Huang Shiqiang Zhou Zejun Zhang Caiquan Zhou Hemin Zhang Jianguo Liu 《Ecology and evolution》2017,7(8):2575-2584
The study of wildlife activity patterns is an effective approach to understanding fundamental ecological and evolutionary processes. However, traditional statistical approaches used to conduct quantitative analysis have thus far had limited success in revealing underlying mechanisms driving activity patterns. Here, we combine wavelet analysis, a type of frequency‐based time‐series analysis, with high‐resolution activity data from accelerometers embedded in GPS collars to explore the effects of internal states (e.g., pregnancy) and external factors (e.g., seasonal dynamics of resources and weather) on activity patterns of the endangered giant panda (Ailuropoda melanoleuca). Giant pandas exhibited higher frequency cycles during the winter when resources (e.g., water and forage) were relatively poor, as well as during spring, which includes the giant panda's mating season. During the summer and autumn when resources were abundant, pandas exhibited a regular activity pattern with activity peaks every 24 hr. A pregnant individual showed distinct differences in her activity pattern from other giant pandas for several months following parturition. These results indicate that animals adjust activity cycles to adapt to seasonal variation of the resources and unique physiological periods. Wavelet coherency analysis also verified the synchronization of giant panda activity level with air temperature and solar radiation at the 24‐hr band. Our study also shows that wavelet analysis is an effective tool for analyzing high‐resolution activity pattern data and its relationship to internal and external states, an approach that has the potential to inform wildlife conservation and management across species. 相似文献
5.
A photo‐responsive F‐box protein FOF2 regulates floral initiation by promoting FLC expression in Arabidopsis
下载免费PDF全文
![点击此处可从《The Plant journal : for cell and molecular biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Reqing He Xinmei Li Ming Zhong Jindong Yan Ronghuan Ji Xu Li Qin Wang Dan Wu Mengsi Sun Dongying Tang Jianzhong Lin Hongyu Li Bin Liu Hongtao Liu Xuanming Liu Xiaoying Zhao Chentao Lin 《The Plant journal : for cell and molecular biology》2017,91(5):788-801
Floral initiation is regulated by various genetic pathways in response to light, temperature, hormones and developmental status; however, the molecular mechanisms underlying the interactions between different genetic pathways are not fully understood. Here, we show that the photoresponsive gene FOF2 (F‐box of flowering 2) negatively regulates flowering. FOF2 encodes a putative F‐box protein that interacts specifically with ASK14, and its overexpression results in later flowering under both long‐day and short‐day photoperiods. Conversely, transgenic plants expressing the F‐box domain deletion mutant of FOF2 (FOF2ΔF), or double loss of function mutant of FOF2 and FOL1 (FOF2‐LIKE 1) present early flowering phenotypes. The late flowering phenotype of the FOF2 overexpression lines is suppressed by the flc‐3 loss‐of‐function mutation. Furthermore, FOF2 mRNA expression is regulated by autonomous pathway gene FCA, and the repressive effect of FOF2 in flowering can be overcome by vernalization. Interestingly, FOF2 expression is regulated by light. The protein level of FOF2 accumulates in response to light, whereas it is degraded under dark conditions via the 26S proteasome pathway. Our findings suggest a possible mechanistic link between light conditions and the autonomous floral promotion pathway in Arabidopsis. 相似文献
6.
Increasing reports suggest that deregulated microRNAs (miRNAs) might provide novel therapeutic targets for cancers. However, the expression and function of miR-300 in osteosarcoma is still unknown. In our study, we found that the expression of miR-300 was up-regulated in osteosarcoma tissues and cells compared with paired adjacent non-tumor bone tissues and osteoblastic cells using RT-qPCR. The enforced expression of miR-300 could promote cell proliferation, invasion and epithelial-mesenchymal transition (EMT). Moreover, we identified that bromodomain-containing protein 7 (BRD7), a new tumor suppressor gene, was a direct target of miR-300. Ectopic expression of BRD7 could significantly inhibit miR-300-promoted proliferation, invasion and EMT. Therefore, our results identify an important role for miR-300 in osteosarcoma through regulating BRD7 expression. 相似文献
7.
8.
近年来花生微卫星标记的开发取得了一定的进展, 初步揭示了花生在DNA水平上的遗传多样性。花生微卫星标记的开发途径主要包括通过构建小片段基因组文库开发基因组SSR标记, 根据花生EST序列开发EST-SSR标记, 根据豆科植物序
列信息和SSR标记开发花生SSR标记, 将SSR标记与其它分子标记结合开发新的DNA标记, 以及基于SSR核心序列开发ISSR标记。花生微卫星标记主要应用于遗传多样性研究、遗传图谱与品种指纹图谱构建以及分子标记辅助育种等领域。本文综述了花生SSR标记开发研究的进展及应用。 相似文献
9.
Wei Gao Yongxun Jin Jindong Hao Siyi Huang Dongxu Wang Fushi Quan Wenzhi Ren Jiabao Zhang Mingjun Zhang Xianfeng Yu 《Molecular reproduction and development》2021,88(1):55-66
Oxidative stress negatively affects the in vitro maturation (IVM) of oocytes. Procyanidin B1 (PB1) is a natural polyphenolic compound that has antioxidant properties. In this study, we investigated the effect of PB1 supplementation during IVM of porcine oocytes. Treatment with 100 μM PB1 significantly increased the MII oocytes rate (p <0.05), the parthenogenetic (PA) blastocyst rate (p <0.01) and the total cell number in the PA blastocyst (p < 0.01) which were cultured in regular in vitro culture (IVC) medium. The PA blastocyst rate of regular MII oocytes activated and cultured in IVC medium supplemented with 100 and 150 μM PB1 significantly increased compared with control (p < 0.01 and p < 0.05). We also evaluated the reactive oxygen species (ROS) levels, mitochondrial membrane potential (Δψm) levels, glutathione (GSH) levels, and apoptotic levels in MII oocytes and cumulus cells following 100 μM PB1 treatment. The results showed that the PB1 supplementation decreased ROS production and apoptotic levels. In addition, PB1 was found to increase Δψm levels and GSH levels. In conclusion, PB1 inhibited apoptosis of oocytes and cumulus cells by reducing oxidative stress. Moreover, PB1 improved the quality of oocytes and promoted PA embryo development. Taken together, our results suggest that PB1 is a promising antioxidant additive for IVM of oocytes. 相似文献
10.
Jindong Shi Juan Xie Zebao He Yunwen Hu Yanchao He Qihui Huang Beizheng Leng Wei He Ying Sheng Fangming Li Yuanlin Song Chunxue Bai Yong Gu Zhijun Jie 《PloS one》2013,8(10)