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   20篇
  免费   0篇
  国内免费   6篇
  2023年   1篇
  2020年   2篇
  2019年   2篇
  2015年   1篇
  2013年   1篇
  2012年   1篇
  2010年   3篇
  2009年   2篇
  2007年   1篇
  2003年   1篇
  2002年   2篇
  2000年   3篇
  1998年   1篇
  1995年   1篇
  1993年   1篇
  1992年   1篇
  1989年   1篇
  1967年   1篇
排序方式: 共有26条查询结果,搜索用时 0 毫秒
1.
董炜华  殷秀琴  魏健 《四川动物》2012,31(2):259-263
本文研究了赤子爱胜蚓在长春市城郊不同组合的粮食猪粪、饲料猪粪和玉米、水稻秸杆混合物中生长繁殖状况,结果发现赤子爱胜蚓的质量在0 ~30 d大幅度增加,30 ~ 60 d增加减缓,60~ 90 d呈负增长趋势.赤子爱胜蚓产茧量在试验期间的总趋势是递增的.猪粪种类、秸杆种类和两者的混合比例差异对赤子爱胜蚓的质量变化产生重要影响.粮食猪粪和玉米秸杆混合物的质量比例大致在1∶1时特别适宜赤子爱胜蚓生长和繁殖.赤子爱胜蚓在饲料猪粪和玉米秸杆混合物中的日增重倍数和日产茧量多于饲料猪粪和水稻秸杆混合物.本试验结论可为城郊猪粪和作物秸杆的大规模资源化利用提供参考.  相似文献   
2.
诸葛菜茎叶中黄酮类化合物的研究   总被引:4,自引:0,他引:4  
诸葛菜茎叶乙醇提取物用Mg+HCl,Zn+HCl,1%FeCl3-乙醇液,1%NaOH进行显色反应,呈现黄酮类化合物性质特征颜色。又以槲皮素,山柰酚,异鼠李素为对照品,采用HPLC法分析测定了其茎叶中黄酮醇的含量。结果表明干品中总黄酮含量(以甙元计)为0.568%。  相似文献   
3.
三七植物各部位的研究和开发利用   总被引:1,自引:0,他引:1  
本文报道了对三七根、绒根、根茎、茎叶、花蕾,果实,果梗等的化学成分研究;皂甙提取分离方法;皂甙及黄酮类成分的生理活性及新药开发利用等的研究概况。  相似文献   
4.
Natural cellulose fibers have been obtained from the bark of cotton stalks and the fibers have been used to develop composites. Cotton stalks are rich in cellulose and account for up to 3 times the quantity of cotton fiber produced per acre. Currently, cotton stalks have limited use and are mostly burned on the ground. Natural cellulose fibers obtained from cotton stalks are composed of approximately 79% cellulose and 13.7% lignin. The fibers have breaking tenacity of 2.9 g per denier and breaking elongation of 3% and modulus of 144 g per denier, between that of cotton and linen. Polypropylene composites reinforced with cotton stalk fibers have flexural, tensile and impact resistance properties similar to jute fiber reinforced polypropylene composites. Utilizing cotton stalks as a source for natural cellulose fibers provides an opportunity to increase the income from cotton crops and make cotton crops more competitive to the biofuel crops.  相似文献   
5.
Achnanthes longipes Ag. is a marine stalk‐forming diatom that grows in dense biofilms. The effects of cell density, temperature, and light on growth and stalk production were examined in the laboratory to determine how they affected the ability of this diatom to form a biofilm. Stalk production abruptly increased when A. longipes was cultured at a density of 5.4 × 103 cells·mL ? 1 1 Received 23 February 2002. Accepted 22 July 2002.
, with a lag before stalk production occurring in cultures initiated at lower densities. Growth occurred at all temperatures from 8 to 32° C, with maximum growth at 26° C. Growth rate was light saturated at 60 μmol photons·m ? 2·s ? 1 1 Received 23 February 2002. Accepted 22 July 2002.
. Stalk production was determined as the proportion of cells producing stalks and stalk length in response to various temperatures and light intensities at high (5000 cells·mL ? 1 1 Received 23 February 2002. Accepted 22 July 2002.
) and low (500 cells·mL ? 1 1 Received 23 February 2002. Accepted 22 July 2002.
) densities. More cells formed stalks at high density, with no difference in stalk length. The proportion of cells producing stalks was maximal at 20° C, with little change at 17–32° C. Stalk length was at a maximum between 14 and 26° C. Stalk production showed little change in response to varying light intensity. The results of an earlier investigation on the effects of bromide concentration on stalk formation were expressed as the proportion of cells forming stalks and the lengths of the stalks. Both measures of stalk production varied with bromide concentration, with maximum values at 30 mM bromide. The increased stalk production at higher densities may be a means of elevating cells above the substrate to avoid competition in the dense biofilm.  相似文献   
6.
Diopsid flies have eye stalks up to a centimeter in length, displacing the retina laterally from the rest of the head. This bizarre condition, called hypercephaly, is rare, but has evolved independently among several insect orders and is most common in flies (Diptera). Earlier studies of geometrical optics and behavior have led to various hypotheses about possible adaptive advantages of eye stalks, such as enhanced stereoscopic vision while other hypothesis suggest that eye stalks are an outcome of sexual selection. Here, we focus on how these curious distortions of head/eye morphology are accompanied by changes in the neural organization of the visual system of Cyrtodiopsis quinqueguttata. Histological examinations reveal that the optic lobes, lamina (La), medulla (Me), lobula (Lo), and lobula plate (LP) are contained entirely within the fly's eye bulbs, which are located at the distal ends of the eye stalks. We report that the organization of the peripheral visual system (La and Me) is similar to that of other Diptera (e.g., Musca and Drosophila), but deeper visual areas (Lo and LP) have been more strongly modified. For example, in both the lobula and lobula plate, fewer but larger giant collector neurons are found. The most pronounced difference is the reduction in the number of wide-field vertical cells of the lobula plate, where there are only four relatively large fibers, as opposed to 11 in Musca. The “fewer but larger” neural organization may enhance the conduction velocities of these cells, but may result in a loss of spatial resolution. At the base of the eye bulb, axon bundles collect and form a long optic nerve that extends the length of the eye stalk. We suggest that this organization of the diopsid visual system provides evidence for the costs of possessing long eye stalks. © 1998 John Wiley & Sons, Inc. J Neurobiol 37: 449–468, 1998  相似文献   
7.
利用玉米秸秆栽培平菇有着原料来源广、就地取材等优点,但由于玉米秸秆切成段后栽培平菇,保水性差,体积大,产量低,为了克服这些不足之处,在无棉区开辟代料栽培平菇的新途径,我们采用玉米秸秆粉碎后栽培平菇,取得了较好的效果。  相似文献   
8.
9.
Different agricultural wastes, namely tobacco stalk (TS), cotton stalk (CS), sunflower stalk (SS), and wheat straw (WS), were used for the production of xylooligosaccharide (XO). XO production was performed by acid hydrolysis of xylan, which was obtained by alkali extraction from these agricultural wastes. The major component of these agricultural wastes was determined as cellulose (30-42%), followed by xylan (20%) and lignin (20-27%). Xylans from these wastes had mainly xylose (85-96%) with small amount of glucose, while wheat straw xylan contained also arabinose. The best xylan conversion into XOs was achieved with 0.25 M H2SO4 with 30-min reaction time. Under these conditions, the XO yield was between 8% and 13%. The yield of XOs depends on both acid concentration and hydrolysis time, but the yield of monosaccharide depends on the structure and composition of xylan besides acid concentration and the time. The more branched xylan, WSX, gave the highest monosaccharide (∼16%) and furfural (∼49 mg/100 g xylan) yield. This research showed that all xylans from selected agricultural wastes generated XOs with similar profiles, and these oligosaccharides could be used as functional food ingredients or soluble substrates for xylanases.  相似文献   
10.
【目的】本试验旨在利用16SrDNA高通量测序技术研究不同比例微贮棉秆的添加对断奶湖羊瘤胃微生物区系的影响。【方法】选择日龄相近、体重相似的湖羊30只,根据日粮中微贮棉秆的含量随机分为3组:对照组(S0)、50%微贮棉秆组(S50)和100%微贮棉秆组(S100),每组随机屠宰6只分析生长性能,并取瘤胃液进行瘤胃发酵参数和微生物区系分析。【结果】饲喂50%微贮棉秆能够显著提高湖羊日增重和屠宰率(P0.05)。Bacteroidetes和Firmicutes是湖羊瘤胃的优势菌门,Prevotella和Unclassified Bacteroidales是湖羊瘤胃的优势菌属。日粮中添加100%微贮棉秆可以显著降低湖羊瘤胃菌群的多样性(P0.05);显著降低Unclassified Bacteroidales和BF311的相对丰度(P0.05)。三条代谢通路甜菜素生物合成、吲哚生物碱生物合成和加压素调节水的重吸收随着微贮棉秆比例升高而显著增加(P0.05)。【结论】饲喂50%微贮棉秆在提高日增重的同时对湖羊瘤胃微生物菌群结构与功能影响较小。在生产实践中,微贮秸秆添加量应低于50%。  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