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   110篇
  免费   11篇
  国内免费   20篇
  2023年   4篇
  2022年   5篇
  2021年   7篇
  2020年   6篇
  2019年   4篇
  2018年   7篇
  2017年   2篇
  2016年   8篇
  2015年   7篇
  2014年   18篇
  2013年   9篇
  2012年   8篇
  2011年   8篇
  2010年   5篇
  2009年   5篇
  2008年   11篇
  2007年   5篇
  2006年   5篇
  2005年   8篇
  2004年   1篇
  2003年   1篇
  2002年   3篇
  2001年   1篇
  2000年   1篇
  1998年   1篇
  1992年   1篇
排序方式: 共有141条查询结果,搜索用时 15 毫秒
1.
Antheraea pernyi is a semi‐domesticated lepidopteran insect species valuable to the silk industry, human health, and ecological tourism. Owing to its economic influence and developmental properties, it serves as an ideal model for investigating divergence of the Bombycoidea super family. However, studies on the karyotype evolution and functional genomics of A. pernyi are limited by scarce genomic resource. Here, we applied PacBio sequencing and chromosome structure capture technique to assemble the first high‐quality A. pernyi genome from a single male individual. The genome is 720.67 Mb long with 49 chromosomes and a 13.77‐Mb scaffold N50. Approximately 441.75 Mb, accounting for 60.74% of the genome, was identified as repeats. The genome comprises 21,431 protein‐coding genes, 85.22% of which were functionally annotated. Comparative genomics analysis suggested that A. pernyi diverged from its common ancestor with A. yamamai ~30.3 million years ago, and that chromosome fission contributed to the increased chromosome number. The genome assembled in this work will not only facilitate future research on A. pernyi and related species but also help to progress comparative genomics analyses in Lepidoptera.  相似文献   
2.
生境梯度影响下的天然红松种群空间格局与种内关联   总被引:1,自引:0,他引:1  
董雪  杜昕  孙志虎  谷会岩  陈祥伟 《生态学报》2020,40(15):5239-5246
为理清生境梯度下天然红松种群空间分布规律,以黑龙江省凉水国家级自然保护区内自坡底至坡顶的四种生境(生境Ⅰ,谷地平坡潮湿生境;生境Ⅱ,坡下缓坡潮湿生境;生境Ⅲ,坡上斜坡半湿润生境;生境Ⅳ,坡顶陡坡半干旱生境)类型中建群种红松种群为研究对象。分析不同林层(主林层、亚林层、演替层、更新层)红松种群的数量特征,并基于O-ring函数,在重复采样条件下评价了红松种群空间分布格局。结果表明:(1)下坡位生境(生境Ⅰ、Ⅱ)红松更新层种群数量显著大于上坡位(生境Ⅲ、Ⅳ)(P0.05),演替层中差异不显著;自坡底至坡顶的生境梯度上,主林层和亚林层中红松株数比例增加,红松种群年龄结构结构由倒J型向J型转变。(2)下坡位原始红松林更新层和演替层中红松种群聚集规模与聚集强度均高于上坡位,坡顶(生境Ⅳ)原始红松林更新层中红松种群聚集规模与聚集强度高于坡上(生境Ⅲ)。(3)四类生境的原始红松林中主林层与更新层中红松种群总体表现为空间独立,在个别尺度上表现出微弱的空间正关联或负关联;在0—5 m尺度上,下坡位红松林原始林内演替层与主林层红松种群表现为空间负关联,而上坡位生境林分对应林层间空间关系则为空间正关联;四类生境中,亚林层与主林层中红松种群在全部研究尺度上均表现为空间独立。可以认为,造成上坡位生境的原始红松林中幼树、幼苗聚集规模与强度弱于下坡位的原因是上坡位更新与演替层中种群数量较少;而随坡位上升,更现层、演替层与主林层中红松种群间的空间关系由空间负关联向空间正关联转变是生物与非生物因子共同作用的结果。研究结果为阔叶红松林的经营管理与生态修复提供了理论依据。  相似文献   
3.
以青砖茶、新鲜苹果汁、西瓜汁和菠萝汁为主要原料进行果茶饮料的研制,采用单因素试验及正交分析试验对果茶饮料的配方进行工艺优化,以感官评价和吸光值为评定指标,确定果茶饮料的最佳配方。结果表明,体积比分别为8∶2的茶汤与苹果汁的混合汁、5∶5的茶汤与西瓜汁的混合汁和3∶7的茶汤与菠萝汁的混合汁混匀调配出的茶饮料的口感最佳,色泽清透,且香气较佳。本研究为黑茶果茶饮料的研 制提供了理论依据。  相似文献   
4.
5.
6.
Two types of all‐small‐molecule ternary solar cells consisting of two small‐molecule donors and one acceptor (fullerene/non‐fullerene) are developed. Interestingly, both these devices have a common component: a carefully designed medium bandgap small molecule, which possesses appropriate energy levels and displays good compatibility with the host donor. In the fullerene system, the charge‐relaying role of the additive donor is confirmed by the improved charge transportation and suppressed charge recombination. While in the non‐fullerene system, the mixed face‐on and edge‐on orientation of the ternary film induced by the additive donor dominates the promotion of charge transportation. Accordingly, both ternary devices deliver higher short‐circuit current density, fill factor, and power conversion efficiencies of over 10% compared to binary ones. This work offers a promising guideline on the construction of high‐performance all‐small‐molecule ternary solar cells by incorporating a miscible small‐molecule donor.  相似文献   
7.
The abundantly expressed carcinoembryonic antigen (CEA) on several cancer types is an attractive target for antibody-directed therapy. However, CEA is also present in some normal tissues. Here, we produced a dual functioning protein, designated as CAtin that exhibits both specific binding and killing functions, by fusing a tumor-specific apoptosis-inducing molecular Apoptin to C-terminus of an anti-CEA single-chain disulfide-stabilized Fv antibody (scdsFv). The CAtin proteins were expressed in Escherichia coli (E. coli), refolded and purified on an immobilized Ni2+ affinity chromatography column. SDS–PAGE and Western blotting revealed that the recombinant protein was well-expressed and the yield was approximately 250 mg/L. We demonstrated by flow cytometry and immunofluorescence assays that CAtin could bind specifically to human colon carcinoma cells (LoVo), but almost not to human uterine cervix (Hela). The results suggest that CAtin is active and specific toward CEA-positive cells and may potentially be used in CEA-targeted cancer therapy.  相似文献   
8.
9.
Gu  Junfei  Sun  Ruolan  Tang  Decai  Liu  Fuyan  Chang  Xiangwei  Wang  Qiaohan 《Cell biology and toxicology》2022,38(4):679-697
Cell Biology and Toxicology - Colorectal cancer (CRC) is regarded as one of the commonest cancer types around the world. Due to the poor understanding on the causes of CRC formation and...  相似文献   
10.
研究了四川盆地低山丘陵区马尾松人工林不同大小林窗对表层土壤活性有机碳(水溶性有机碳、微生物量碳、易氧化碳)含量、分配比例及碳库管理指数的影响。结果表明:(1)林窗下土壤微生物量碳含量与分配比例较林下土壤有所升高,而水溶性有机碳与易氧化碳含量及水溶性有机碳分配比例有所降低。(2)林窗大小显著影响林窗中心土壤活性有机碳含量与分配比例。随林窗面积增大,水溶性有机碳、微生物量碳与易氧化碳含量呈现较为一致的升高趋势;水溶性有机碳和微生物量碳分配比例也升高,易氧化碳分配比例先下降后升高,稳定态碳先升高后降低;总体表现为较大林窗(900—1225m2)微生物活性强,活性有机碳含量高,且有机碳库稳定性较好。(3)土壤碳库管理指数随林窗面积增大无显著变化,但与各形态活性有机碳含量及总有机碳含量显著相关,说明土壤碳库管理指数能够相对全面地反映林窗大小对土壤碳库的影响。  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