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   62篇
  免费   4篇
林业   25篇
农学   4篇
  4篇
综合类   20篇
农作物   3篇
水产渔业   3篇
畜牧兽医   4篇
园艺   1篇
植物保护   2篇
  2021年   2篇
  2019年   4篇
  2017年   4篇
  2016年   7篇
  2015年   5篇
  2014年   1篇
  2013年   6篇
  2012年   9篇
  2011年   1篇
  2010年   3篇
  2009年   1篇
  2008年   1篇
  2007年   2篇
  2006年   4篇
  2005年   2篇
  2004年   2篇
  2003年   2篇
  2002年   1篇
  2001年   2篇
  2000年   1篇
  1998年   1篇
  1997年   1篇
  1995年   1篇
  1990年   2篇
  1988年   1篇
排序方式: 共有66条查询结果,搜索用时 31 毫秒
31.
Background: Hematologic and plasma biochemical evaluations are routinely used in evaluating the chelonian patient, but appropriate processing techniques have been minimally defined.
Objectives: This study was designed to compare the effects of temperature, time, anticoagulant, and species on sodium and potassium values in the Aldabra tortoise ( Geochelone gigantea ) and the Burmese mountain tortoise ( Manouria emys ).
Methods: Blood samples from 7 Aldabra tortoises and 8 Burmese mountain tortoises were collected into tubes without anticoagulant and tubes containing lithium heparin. Sodium and potassium concentrations were measured by flame photometry in serum and plasma harvested immediately after collection and from aliquots of whole blood stored at 4°C and 25°C for 5 to 120 minutes.
Results: In Aldabra tortoises, storage time and temperature had no significant effect on potassium concentrations in heparinized blood and in blood without anticoagulant. However, sodium concentrations in serum and plasma decreased significantly in samples without anticoagulant stored at 4°C and 25°C and in heparinized samples stored at 4°C. In Burmese mountain tortoises, potassium concentrations in serum and plasma increased significantly with time in samples without anticoagulant and in heparinized samples stored at 4°C and 25°C, but the increases were less at 4°C. Sodium concentrations in serum and plasma decreased significantly in blood without anticoagulant and heparinized blood stored at 4°C and 25°C.
Conclusions: Storage of blood samples with and without anticoagulant at 4°C significantly improved the stability of potassium and sodium concentrations in both species of tortoises. Early separation of red cells from serum or plasma after blood collection is especially important to ensure the reliability of potassium measurements.  相似文献   
32.
瘤坚大球蚧生物学特性及防治技术研究   总被引:1,自引:0,他引:1  
瘤坚大球蚧[Eulecaniumgigantea(Shinji)]是为害国槐的主要害虫之一。在太原1年1代,以2龄若虫在国槐1年生至3年生枝条上越冬。树冠喷洒40%氧化乐果500倍~800倍液、2.5%敌杀死1000倍~2000倍液,或65%多磷威1000倍~2000倍液,干基打孔注(塞)入40%氧化乐果原液、65%多磷威5倍液、铁灭克8g·株-1,均能取得理想的防治效果。  相似文献   
33.
瘤坚大球蚧EulecaniumgiganteaShinji近年来是我国城市林木的重要害虫。作者于 1 998~ 1 999年在太原市和太谷县城设点 ,测定了该蚧虫的寄主树木国槐Sophorajaponica ,体内维生素B2 (VB2 )的变化规律 ,用蚧虫的虫口密度和生物学节律相对照 ,分析了污染—VB2 含量—蚧虫种群消长之间的关系。结果证明 ,污染区国槐枝条和叶片的VB2 含量极显著地高于清洁区 ;VB2 的变化与虫口密度呈正相关关系 ,回归式为Y =1 50 7.76x-1 70 .56,相关系数r=0 .839。在一年中 ,VB2 的含量呈现两个高峰期 ,正好与该蚧虫的两个取食期相吻合。由此认为 ,污染使树体内VB2 含量增高很可能是促进该蚧虫种群增长的一个原因  相似文献   
34.
本文运用树干解析的方法,研究了自然生长条件下湘西巨紫荆树高、胸径、材积、生长率和胸高形数的生长变化规律,结果表明:随着树龄的增长,巨紫荆树高、胸径、材积的总生长量逐步增加,20 a还未达到最大值;树高连年生长量和平均生长量在树龄15 a前都呈现出上升趋势,15 a后逐渐下降;胸径总生长量在20 a前随着树龄的增加几乎呈...  相似文献   
35.
调查分析东川、元江和元阳3个干热河谷居群的牛角瓜结实等特征。结果表明,1元阳居群的牛角瓜单株结实量、单位冠幅结实量和单枝结实量最高,分别为102.4个/株、35.1个/m2和34.6个/枝,且3个居群间这3个指标差异极显著;2居群内单株、单位冠幅和单枝结实量3个指标差异极显著;3各居群的单株结实量与单枝结实量、单位冠幅结实量和分枝相关性状间呈线性相关。元阳是牛角瓜人工栽培的首选区域,通过对结实量大的优良单株进行选育,可极大地提高其果实产量。  相似文献   
36.
【目的】明确牛角瓜[Calotropisgigantea(Linn.)W. T. Aition]大孢子与小孢子的发生发育情况,为其耕作栽培学及植物学研究提供基础资料,也为其遗传育种研究及品种改良打下基础。【方法】于盛花期采集不同发育时期的牛角瓜花蕾,运用石蜡切片技术观察其大孢子与小孢子的发生发育特征。【结果】牛角瓜大孢子与小孢子的发育时期与其花器官外部形态特征存在对应关系,雄蕊的发生发育早于雌蕊。牛角瓜小孢子黏连成块状结构,与普通植物的分散型小孢子形成鲜明对比,其小孢子母细胞发育为连续型,绒毡层细胞有3~4层,为腺质绒毡层,单核期绒毡层细胞壁开始降解,花粉成熟后绒毡层细胞自溶。胚囊发育类型为蓼型,胚珠横生,无珠被;四分体呈线型排列,成熟胚囊有次生核。【结论】牛角瓜大、小孢子发生及雌、雄配子体发育与花器官外部形态大小密切相关,其结实率低并非雌性或雄性败育所致。  相似文献   
37.
Interspecific hybrids between Haliotis discus hannai Ino and Haliotis gigantea Gmelin were produced in this study. The hybridity of the interspecific hybrids was confirmed by using the methods of amplified fragment‐length polymorphism (AFLP) and microsatellite [simple sequence repeats (SSR)] markers. Five AFLP primer combinations were used to develop the AFLP profiles of H. discus hannai, H. gigantea and their reciprocal hybrids. AFLP analysis revealed that genetic variations of H. discus hannai and H. gigantea were relatively diverse and each species holds species‐specific bands. The AFLP profiles of reciprocal hybrids showed that all of the hybrids inherited bands specific to H. discus hannai and H. gigantea. Of a total of 20 microsatellite loci, which were selected from H. discus hannai microsatellite markers evaluated, eight loci were polymorphic in H. gigantea samples, with an average of 3.375 alleles per locus. Preliminary screening showed that, two of these eight microsatellite loci (Awb002 and Awb022) could be used as species‐specific markers to distinguish the hybrids and their parental species. Simple sequence repeats analysis showed that the reciprocal hybrids inherited one allele from each parent for both of the two SSR loci investigated. These data strongly suggest that the induced interspecific hybrid is a true hybrid between H. discus hannai and H. gigantea.  相似文献   
38.
以阴生桫椤(Alsophila latebrosa)、大叶黑桫椤(Alsophila gigantea)为研究对象,利用绿色球状体(Green Globular Bodies,GGB)途径,展开快繁体系的研究,以筛选最优的繁殖体系。结果表明:(1)阴生桫椤的快繁体系中,1/10 MS是孢子萌发最优培养配方;1/2 MS+NAA 0.3 mg/L+6-BA 0.5 mg/L,蔗糖30 g/L,琼脂6.5 g/L是诱导配子体产生GGB的最优培养配方;1/2 MS+KT 0.1 mg/L+IAA 0.1 mg/L是其诱导GGB分化的最优培养配方;孢子体幼苗在泥炭土:菜园土:珍珠岩=3:3:1的基质中成活率最高。(2)在大叶黑桫椤的快繁体系中,1/10 MS为相对较好的培养基;1/2 MS+0.3 mg/L IBA是诱导产生GGB的最优培养配方;1/2 MS+0.3 mg/L NAA对GGB分化的促进作用最显著;1/2 MS+0.1 mg/L IAA+0.3 mg/L NAA的组合可有效促进孢子体幼苗生根。(3)通过配子体诱导GGB途径,2种桫椤属植物从孢子萌发到幼苗移栽的整个培养过程为6~8个月。可见,GGB途径不仅能提高繁殖系数,也能大大缩短桫椤属植物的繁殖时间,为实现桫椤属植物的工厂化育苗奠定了基础。  相似文献   
39.
A bio-inoculation experiment was performed on Ruta graveolens L., known as “Garden Rue” seedlings for the biomass production. Seedlings were inoculated with single and in combined mycorrhizal treatments. All inoculated seedlings showed significant biomass production than control seedlings. The phosphorus (P) content was more in seedlings inoculated with consortium of three native VAM fungi followed by Glomus mosseae, Acaulospora laevis and Gigaspora gigantea alone treatments. The control seedlings had the least P content but root P content was more than shoot P content in all treatments. The biomass of shoot and root was also significantly more in seedlings inoculated with consortium followed by G. mosseae, A. laevis and G. gigantea alone treatment. The control seedlings again had low shoot and root biomass. The Biovolume index (Bi) was also high in all inoculated treatments than non-inoculated control but consortium treatment (7.98) had at par Bi than rest of inoculation treatments. The quality index (Qi) value was also high in mixed consortium (1.42) and A. laevis treatment (1.42) each respectively than G. mosseae (1.38) and G. gigantea (1.29) treatments. Control seedlings had low value of Qi (1.27). The present study indicates that G. mosseae, A. laevis, G. gigantea are the best strains of VAM symbionts when mixed together for inoculating the R. graveolens to get higher yield of biomass. A. laevis is also good strain of VAM fungi for the same purpose. The G. gigantea alone proved least effective strain for inoculation purpose in R. graveolens but when mixed together in consortium of native VAM fungi as described above executed good results for enhancing the biomass production.  相似文献   
40.
赵元藩 《林业调查规划》2013,38(1):22-24,28
首次提出木本纺织纤维的中文、英文名词及其木本纺织纤维的概念,提供了构成木本纺织纤维的3个主树种,并就其特性、用途等进行了阐述。命名了水晶棉、山地棉2个木本纺织纤维的商品名。  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