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1.
陕北典型农区大气干湿氮沉降季节变化   总被引:10,自引:0,他引:10       下载免费PDF全文
为了研究大气通过干湿沉降输入到农田土壤的氮通量,2007年6月至2008年5月在陕西榆林和洛川两地进行了为期一年的观测试验.结果表明:榆林和洛川地区大气总无机氮沉降通量分别为22.17和16.95 kg·hm~(-2)·a~(-1),湿沉降分别占95.1%和90.4%,干沉降分别占4.9%和9.6%,两个地区氮沉降均以湿沉降为主.总无机氮沉降中,NO_3~--N分别为12.22和9.24 kg·hm~(-2)·a~(-1),分别占总无机氮沉降量的55.1%和54.5%.由于污染水平、气象条件、下垫面特性等的差异,总无机氮沉降中,湿沉降量和NO_3~--N沉降量均是榆林地区大于洛川地区.  相似文献
2.
陕西榆林春玉米高产田土壤理化性状及根系分布   总被引:7,自引:0,他引:7       下载免费PDF全文
调查分析了陕西榆林2块19500 kg·hm-2以上超高产春玉米田的产量构成、干物质分配和0~100 cm土层根系分布及土壤理化性状指标.结果表明:其种植密度为105000~123000株·hm-2、成穗率97.7%~102.2%、千粒重320 g以上,果穗干物质积累量占整株干物质积累量的60.2%~65.5%.0~100 cm土壤平均容重为1.28~1.33 g·cm-3,层间(每层20 cm)土壤容重、孔隙度和田间持水量均呈“M”型变化.玉米根系主要分布在0~60 cm,0~20 cm土层根系量占根系总量的64.8%~72.1%,20~60 cm土层根系量占根系总量的23.30%~28.17%.根系分布与土壤理化性状关系密切,0~20 cm土层玉米的根系量与土壤有机质、全氮和全磷含量呈显著正相关,20~60 cm土层根系量与土壤容重和田间持水量显著相关.因此,选择通透性和保水保肥能力良好的土壤,实行宽窄行双株密植栽培是获得玉米高产的关键.  相似文献
3.
直翅目昆虫分子系统学研究新进展   总被引:2,自引:0,他引:2  
对1994年以来国内外在直翅目昆虫种群遗传变异及进化、种及种下阶元的分类鉴定、种上阶元的系统发育分析及分子进化等分子系统学方面的研究进展进行了综述.近年来,蝗亚目昆虫分子系统学方面的研究成果较为丰富,而有关螽亚目的分子系统学研究较少.线粒体基因和核基因序列联合分析、整个基因组全序列分析以及分子数据与形态学的密切结合将是分子系统学未来发展的主要研究手段.  相似文献
4.
沙柳木蠹蛾性行为及其性信息素滴度的动态节律   总被引:2,自引:1,他引:1       下载免费PDF全文
 沙柳木蠹蛾Holcocerus arenicola是为害沙柳Salix psammophila的主要钻蛀性害虫之一。在进入暗期后的6 h内,对其求偶行为和交配行为进行观察和记录,调查该虫求偶和交配的活动规律。通过触角电位技术(EAG)和毛细管气相色谱(GC)对性腺体内信息素的滴度进行了分析,以揭示性信息素产生的昼夜节律和雌虫日龄对性信息素合成的影响。结果表明:该虫在暗期0.5~1 h内即开始有求偶行为,最大求偶高峰出现在羽化后的第2晚。交配行为主要发生在暗期的1~2 h内。在各日龄的成虫中,1日龄成虫的交配百分率最高。交配平均时间为24.16±2.64 min,随着日龄的增加,交配时间前移。在实验中,未观察到5~6日龄成虫的交配行为。沙柳木蠹蛾性信息素的体内合成早于求偶行为1~2 h,并在暗期的前2 h内达到峰值。性信息素的滴度随着雌虫日龄的增减而减少,最高值为当日羽化雌虫的腺体提取物。林间诱蛾实验中,处女雌蛾和性腺体提取物对雄蛾均有较好的诱捕效果。本研究表明,在沙柳木蠹蛾的性信息素滴度和性活动之间具有同步关系,同时为进一步利用长距离性信息素防治该虫提供了参考。  相似文献
5.
钙信号是胞内主要的第二信使之一,发挥广泛的作用如细胞分裂、细胞凋亡等,对细胞的生命活动起着非常重要的作用。在精子和卵母细胞中,钙信号对精子获能、顶体反应、卵母细胞成熟、受精及卵裂等一系列复杂的过程有非常重要的影响。现就Ca2 在卵母细胞中的释放机制、信号转导途径、调控功能作一综述。  相似文献
6.
以20%浓度蜂蜜、蔗糖、葡萄糖、果糖、甘露糖为食料,研究了它们对野蚕黑卵卵巢发育和卵子发生的影响。结果表明,与对照相比(蒸馏水),蜂蜜、蔗糖、葡萄糖和果糖能促进野蚕黑卵蜂雌蜂卵巢发育和卵子发生,可使其卵巢管中较高的成熟卵量维持较长时间,即可延缓该蜂的卵子重吸收。甘露糖对野蚕黑卵蜂的卵子形成有一定的促进作用,但其所起的作用显然不如蜂蜜及其它3种糖类,并且也不能延缓该蜂的卵子重吸收。  相似文献
7.
Keratin-associated protein 9.2 (KAP9.2) and Homeobox C13 (Hoxc13) genes were chosen to study because of their biological functions involving hair formation. KAP9.2 gene belongs to the ultra high sulfur KAPs, which is important for hair formation and may have association with cashmere. Hoxc13 takes part in the formation of cashmere keratin and maintaining the normal structure of follicle. It has been reported that Hoxc13 gene exists binding site of KP and KAP genes at its promoter regions in mouse. So the expression of KAP9.2 and Hoxc13 genes was detected at anagen stage vs telogen stage by qRT-PCR. The data showed that KAP9.2 and Hoxc13 gene had similar expression trend at different stages, which indicated that there was interaction between them. KAP9.2 and Hoxc13 gene had lower expression level in anagen than that of in telogen of cashmere growth. In anagen, KAP9.2 and Hoxc13 expressed lower in high cashmere yield individuals than that of in low cashmere yield ones. In telogen, the result was reverse. The study would provide the evidence of involvement of KAP9.2 and Hoxc13 in hair periodic growth.  相似文献
8.
TP53 is known as a tumor suppressor gene involved in cell cycle regulation. Many previous epidemiological and clinical studies have evaluated the effects of rs1042522 polymorphism on risk of ovarian cancer. But the results are conflicting and heterogeneous. The primary objective of this study was to examine whether rs1042522 polymorphism is associated with ovarian cancer risk. We performed a comprehensive meta-analysis of 19 case–control studies that analyzed rs1042522 polymorphism in ovarian cancer risk. Odds ratios (ORs) were calculated using distinct genetic models. Heterogeneity between studies was detected by the χ2-based Q test. Additional analyses such as sensitivity analyses and publication bias were also performed. The rs1042522 polymorphism was not overall associated with ovarian cancer risk. But there was a borderline association in the heterozygote model (OR = 1.09, 95 % CI 0.99–1.21). Similar effects were observed in the subgroup of Caucasian population (the heterozygote model: OR = 1.11, 95 % CI 1.00–1.24). No significant heterogeneity and publication bias were revealed in this meta-analysis. This study provides statistical evidence that TP53 rs1042522 polymorphism may play a role in modulating risk of ovarian cancer. This observation requires further analysis of a larger study size.  相似文献
9.
Keratin-associated proteins 9.2 (KAP9.2) gene encodes one of the ultra high sulfur KAPs. Variation in KAP genes may affect the structure of KAPs and hence cashmere characteristics. In order to test the association between the polymorphism of KAP9.2 gene and cashmere trait, DNA sequencing was used to detect a novel C/T polymorphism of KAP9.2 gene from a genomic DNA pool. The mutation could be recognized by Pst I restriction enzyme. To Shanbei white cashmere goat, Inner Mongolia white cashmere goat and Guanzhong dairy goat, the genotypic frequencies of TT, TC and CC from total 1,236 animals were as follows: 0.047, 0.519 and 0.434; 0.180, 0.592 and 0.228; 0.431, 0.544 and 0.025. The allelic frequencies of T and C were 0.307 and 0.693; 0.476 and 0.524; 0.703 and 0.297, respectively, in breeds mentioned above. The frequency of C allele between cashmere and dairy goat was significant (P?<?0.01). To provide support for the hypothesis that SNP 586 was responsible for KAP9.2 expression, quantitative real-time PCR analysis revealed that the expression level of KAP9.2 was reduced in individuals bearing genotype CC compared with TT individuals, suggesting that C was the nucleotide causing decreased expression of KAP9.2 or was in linkage disequilibrium with the causative SNP. The 586C/T SNP found in this study might control translation or stability of KAP9.2 mRNA, which would be beneficial for marker assistant selection in cashmere goat breeding.  相似文献
10.
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