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   5篇
  免费   0篇
  国内免费   6篇
  2019年   1篇
  2015年   2篇
  2013年   1篇
  2007年   1篇
  2006年   1篇
  2004年   3篇
  2001年   1篇
  1999年   1篇
排序方式: 共有11条查询结果,搜索用时 15 毫秒
1.
张杰  王超然  姚婷 《菌物学报》2019,38(4):545-559
环链棒束孢广泛存在于自然界,并且在植物病虫害防治中起重要作用,目前相关的研究多集中于其发酵条件、生物学特性及杀虫毒力的研究,对该菌发酵液中的化学物质研究甚少。本文依次用石油醚和乙酸乙酯对环链棒束孢发酵液进行分级萃取,借助气相色谱-质谱(GC-MS)联用技术和超高效液相色谱串联四级杆飞行时间质谱法(UPLC/Q-TOF-MS)鉴定分析石油醚萃取物、乙酸乙酯萃取物和萃余物中的化学物质组成。共鉴定69个化合物的结构,其主要化学成分为酚类、酯类、烷烃、烯烃、卤代烃和酮类非极性/弱极性的小分子化合物等,其中邻苯二甲酸二丁酯、角鲨烯、环戊烯丙菊酯物质、瓜叶菊素Ⅰ等物质具有特殊的作用。发酵液提取物中还含有多种小分子化学物质,应结合多种色谱分离手段和波普学手段对代谢产物进行分离、纯化和结构鉴定,为其次生代谢产物的广泛利用提供数据支撑。  相似文献   
2.
Cuticle micromorphology of 34 taxa of Pinus from Mexico and Central America was studied with scanning electron microscopy, and leaf morphology was described. In total, 29 characters, 22 from the inner cuticular surfaces and seven from the outer, were described in detail. These characters have value either for testing infragenerie classifications or for identifying individual taxa. Characters relating to the periclinal wall texture of the epidermal cells, the shape and degree of development of the anticlinal walls of the epidermal cells, the basal and apical shapes of anticlinal epidermal cell walls, the continuity of the epidermal cells, the size ratio of the polar to lateral subsidiary cells, the grooves on subsidiary cells, the cuticular flanges between guard and subsidiary cells, the groove near the bristles and the elevation of the Florin ring ridge and striations on the Florin ring are particularly useful for infrageneric classification. The agreement between these characters and infrageneric classifications is discussed. Characters relating to the end wall shapes of the epidermal cells, the relative length of epidermal cells, the shape of the stomatal apparatus, the texture of guard and lateral subsidiary cell surfaces, the polar extensions, the number of subsidiary cells and epidermal cell layers between stomatal rows, the integrity of stomatal rows, cell numbers between stomata in a row, cuticular flanges between guard cells, bristle flanges and surface textures, epicuticular waxes, striations on Florin rings and stomatal shapes, contain some important information for identifying Mexican pines. The distribution of the states of each character is compared with that of the Asian pines. Cuticular characters are used to help determine the affinities of taxonomically difficult taxa.  相似文献   
3.
Abstract This study analyzed neuronal responses in the second somatosensory (SII) and 7b cortical areas during a selective attention task. Cues directed attention to one of three simultaneous stimuli: vibrotactile stimuli applied to mirror sites on both hands or to a similarly timed auditory tone. Two stimulus patterns appeared with equal probability for the cued stimulus: a constant amplitude sinewave or the latter with a superimposed brief amplitude pulse midway in the trial. Uncued stimuli always contained amplitude pulses. Monkeys demonstrated whether an amplitude pulse at the cued location was present or absent by making appropriately rewarded up and down foot pedal movements. Cue location and stimulus pattern varied trial-wise and pseudo-randomly. Average firing rates to vibrotactile stimuli in 82 of 181 SII cells and 13 of 22 area 7b cells differed significantly during at least one epoch for trials cued to the contralateral hand when compared to trials cued to the ipsilateral hand or auditory stimulus. Predominant were relatively suppressed firing rates during times prior to the epoch containing the amplitude pulses or enhanced activity during and after these pulses. Generally, different cells showed suppression early vs enhancement later in a trial. Analyses of the ratio between firing rates before and during the amplitude pulses suggested improved evoked signals to the amplitude pulses. The discussion considers attention as a mechanism for reducing distractions, early in the trial through suppressing these signals, or for selectively increasing response magnitudes in the cued channel, especially around times when amplitude pulses were present or absent.  相似文献   
4.
我国果园生草的研究进展   总被引:23,自引:0,他引:23  
目前,世界水果生产先进国家的果园都采用生草模式,唯有中国的果农仍在锄草.为了有效地破解果农“草之祸、草之惑、草之获”问题,推动‘果园生草’这一现代土壤管理模式在我国推广应用,近年来国内有关果园生草的研究报道明显增多.本文结合课题组的相关研究,综述了生草对果园土壤、小气候、病虫害、树体生长及果实品质等的影响研究进展,提出了果园生草必须坚持“因地制宜、经济效益、关键时期、技术配套”的四项基本原则,并对今后的研究方向加以展望.  相似文献   
5.
我国果园生草的研究进展   总被引:1,自引:1,他引:0  
目前,世界水果生产先进国家的果园都采用生草模式,唯有中国的果农仍在锄草.为了有效地破解果农“草之祸、草之惑、草之获”问题,推动‘果园生草’这一现代土壤管理模式在我国推广应用,近年来国内有关果园生草的研究报道明显增多.本文结合课题组的相关研究,综述了生草对果园土壤、小气候、病虫害、树体生长及果实品质等的影响研究进展,提出了果园生草必须坚持“因地制宜、经济效益、关键时期、技术配套”的四项基本原则,并对今后的研究方向加以展望.  相似文献   
6.
以渤海和黄海分离出400多株在低温条件下生长良好的菌株为出发菌株,利用常规筛选方法选出2株低温蛋白酶产生菌(Pseudorrtortas alcaligenes)。经UV、DES、NTG、EMS、LiCl单独及复合诱变,选育出一株(Pa040523)蛋白酶高产突变株。通过单因素实验,确定了Pa040523菌株蛋白酶发酵培养基为:玉米淀粉糖1.8%,尿素0.6%,磷酸氢二钾0.6%,磷酸二氖钾0.3%。该突变株低温蛋白酶产量为940.8U/mg。  相似文献   
7.
提取6株O型口蹄疫病毒(FMDV)(T1-T6)的RNA,用一对通用引物经RT-PCR方法将6株FMDVVP1基因片段扩增出来.克隆测序,核苷酸序列分析表明,T1-T6六株vp1基因的核苷酸序列同源性在95%~99.8%之间,氨基酸序列同源性在94.8%~100%之间.T1-T6六株病毒vp1基因的核苷酸序列与已经发表的O/HKN/14/82、O/TAW/81/97、O/PHI/7/96、O/HKN/1/99和O/HKN/16/96的同源性较高,核苷酸序列同源性在86.1%~95.8%之间;发现6株毒株的主要中和抗原表位140-160、200-213位的氨基酸序列完全相同,推测它们有相近的中和抗体表位和抗原性.故推断本试验中的6株FMDV株属于同一基因型,即FMDV O型中国拓朴型(Cathaytopotype).  相似文献   
8.
Cuticle micromorphology of leaves of Pinus (Pinaceae) from North America   总被引:1,自引:0,他引:1  
Cuticle micromorphology of 31 taxa of Pinus from North America was studied with scanning electron microscopy. Twenty-eight characters, 21 from the inner cuticle and seven from the outer cuticle, were described in detail. These characters have value either for infrageneric classification or for identifying individual taxa. Ten characters were diagnostic for subgenera. Numbers 1−5 relate to the epidermal cells: (1) periclinal wall texture; (2) degree of development; (3) shape of anticlinal walls; (4) shape of apex of anticlinal walls; (5) cuticular continuity. Numbers 6 and 7 relate to the subsidiary cells: (6) lateral texture; (7) groove on the inner surface. Numbers 8−10 relate to the Florin ring: (8) degree of development of the ridge; (9) furrow; (10) groove. Pinus resinosa , belonging to Pinus section Pinus , was clearly distinguished from both the other species and subsection by the tapering and oblique end wall and markedly developed anticlinal walls of the epidermal cells. The cuticular features of P. albicaulis belonging to Parrya subsection Cembrae have a cuticular pattern typical of the species of subgenus Strobus . The subsectional delimitation based on cuticular features did not show a clear resolution even though the taxa might be individually distinct based on the combination of characters examined.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society, 2004, 144 , 303−320.  相似文献   
9.
提取6株O型口蹄疫病毒(FMDV)(T1-T6)的RNA,用一对通用引物经RT-PCR方法将6株FMDVVP1基因片段扩增出来。克隆测序,核苷酸序列分析表明,T1-T6六株vp1基因的核苷酸序列同源性在95%~99.8%之间,氨基酸序列同源性在94.8%~100%之间。T1-T6六株病毒vp1基因的核苷酸序列与已经发表的O/HKN/14/82、O/TAW/81/97、O/PHI/7/96、O/HKN/1/99和O/HKN/16/96的同源性较高,核苷酸序列同源性在86.1%~95.8%之间;发现6株毒株的主要中和抗原表位140-160、200-213位的氨基酸序列完全相同,推测它们有相近的中和抗体表位和抗原性。故推断本试验中的6株FMDV株属于同一基因型,即FMDVO型中国拓朴型(Cathaytopotype)。  相似文献   
10.
云南紫胶虫的地理分布及生态因子的作用   总被引:1,自引:0,他引:1  
陈又清  王绍云 《昆虫学报》2007,50(5):521-527
紫胶虫是重要的资源昆虫。本文结合云南西南部、东南部地区云南紫胶虫自然分布区调查结果及相关资料的整理和分析,对生态因子在云南紫胶虫地理分布中的作用进行了归纳。结果表明:云南紫胶虫的地理起源可能是印度洋地区的南亚。云南紫胶虫主要分布于怒江流域及支流、澜沧江流域及支流、红河流域及支流、伊洛瓦底江流域支流河谷两岸半山坡。气候因子中的温湿度组合是决定云南紫胶虫地理分布的主要因子,而寄主植物分布对云南紫胶虫地理分布也有限制作用。云南特有的流域地形、山脉走向及所形成的小气候特点决定了云南紫胶虫在云南的地理分布格局。  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