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   125篇
  免费   6篇
  国内免费   6篇
林业   14篇
农学   12篇
  24篇
综合类   11篇
农作物   2篇
水产渔业   10篇
畜牧兽医   55篇
园艺   6篇
植物保护   3篇
  2024年   1篇
  2023年   2篇
  2022年   3篇
  2021年   2篇
  2019年   2篇
  2018年   4篇
  2017年   8篇
  2016年   5篇
  2015年   6篇
  2014年   7篇
  2013年   9篇
  2012年   8篇
  2011年   11篇
  2010年   5篇
  2009年   3篇
  2008年   9篇
  2007年   13篇
  2006年   4篇
  2005年   6篇
  2004年   1篇
  2003年   4篇
  2002年   7篇
  2001年   1篇
  2000年   1篇
  1999年   3篇
  1998年   2篇
  1996年   3篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1987年   1篇
  1984年   1篇
  1983年   1篇
  1975年   1篇
排序方式: 共有137条查询结果,搜索用时 15 毫秒
61.
This study was conducted to investigate the developmental capacity of domestic cat-bovine reconstructed embryos via interspecies somatic cell nuclear transfer (iSCNT) and to observe the mitochondrial DNA (mtDNA) content of the iSCNT embryos. The iSCNT embryos were generated using mixed-breed domestic cat fibroblasts as donor cells and enucleated bovine oocytes as the recipient cytoplasm. When the developmental capacities of iSCNT embryos and parthenogenic bovine embryos were compared, there was no difference (P>0.05) in the rates of cleavage and development to the 8-cell stage (86.6 vs. 84.0% and 32.2 vs. 36.2%, respectively). However, in contrast to development of parthenogenic embryos to the morula and blastocyst stages, no iSCNT embryos (0/202) developed beyond the 8-cell stage. For mtDNA analysis, iSCNT embryos at the 1-cell, 2-cell, 4-cell and 8-cell stages were randomly selected. Both cat and bovine mtDNA quantification analysis were performed using quantitative PCR. The levels of both cat and bovine mtDNA in cat-bovine iSCNT embryos varied at each stage of development. The cat mtDNA concentration in the iSCNT embryos was stable from the 1-cell to 8-cell stages. The bovine mtDNA in the iSCNT embryos at the 8-cell stage was significantly lower than that at the 4-cell stage (P<0.05). No difference in the proportions of cat mtDNA in the iSCNT embryos was found in any of the observed developmental stages (1- through 8-cell stages). In conclusion, bovine cytoplasm supports domestic cat nucleus development through the 8-cell stage. The mtDNA genotype of domestic cat-bovine iSCNT embryos illustrates persistence of heteroplasmy, and the reduction in mtDNA content might reflect a developmental block at the 8-cell stage.  相似文献   
62.
波纹巴非蛤的形态分析与营养成分评价   总被引:1,自引:0,他引:1  
文章分析了波纹巴非蛤(Paphia undulate)的形态性状、出肉率及蛤肉的主要营养成分,并综合评价了其营养价值。结果显示,波纹巴非蛤的出肉率达35.73%;蛤肉中蛋白质占鲜质量的12.8%;18种氨基酸总量约占干质量的46.21%,其中8种必需氨基酸(EAA)占氨基酸总量的34.67%,4种鲜味氨基酸占氨基酸总量的41.94%;牛磺酸(Tau)的质量分数较高,占干质量的3.03%;不饱和脂肪酸(UFA)占脂肪酸总量的51.9%,C22:6(DHA)和C20:5(EPA)共占32.8%;矿物质丰富,尤其是钾(K)元素的质量分数高达3.407mg·g-1。  相似文献   
63.
Chiral resolution of imazalil, a fungicide, was performed by capillary electrophoresis (CE) using 2-hydroxypropyl-beta-cyclodextrin as a chiral selector. Factors affecting the chiral resolution and migration time of imazalil were studied. The optimum running conditions were found to be 5 mM ammonium dihydrogenphosphate-50 mM phosphate buffer (pH 3.0) containing 4 mM 2-hydroxypropyl-beta-cyclodextrin with an effective voltage of +25 kV at 20 degrees C using direct detection at 200 nm. Under these conditions, the resolution (Rs) of racemic imazalil was approximately 6. The extraction of imazalil from orange samples was done with acetonitrile under basic conditions. The extract was purified with a solid-phase extraction cartridge (Sep-Pak plus PS-2) and was analyzed by the above CE method. Eight orange samples were analyzed, and imazalil was detected in seven samples. In four of these seven oranges, the level of (-)-imazalil was the same as that of (+)-imazalil, but in the other three oranges, the level of (-)-imazalil was found to be lower than that of (+)-imazalil, suggesting that (-)-imazalil was degraded more quickly than (+)-imazalil in oranges.  相似文献   
64.
Exposing corms to smoke generated from smouldering plant materials (“smoke treatment”) releases freesia corms from dormancy. The smoke was found to contain some hydrocarbons, i.e. ethane, ethylene, (C2H4), and propylene at concentrations below 130 μl 1?1, and carbon monoxide (CO) at 2000-400 μl 1?1.Exogenous C2H4 at low levels of 100-1 μl/litre air strongly stimulated dormancy-release. In contrast, propylene and acetylene were required at a concentration much higher than that in the smoke to exert the dormancy-releasing effect: the application of 100 μl/litre air had little or no effect. Air containing 1000 μl COlitre air produced some effect, which could be masked by co-existence of 10 μl C2H4litre air. Acetaldehyde, which may occasionally be present in smoke, showed the dormancy release at ca. 1 mM but was phytotoxic. Corms exposed to smoke or C2H4 did not show an endogenous C2H4 rise, while non-treated corms showed it distinctly before dormancy release.These results suggest that a C2H4-stimulus is dominant in smoke treatment.  相似文献   
65.
The present study was carried out to analyze the factors that affected the growth of sugar beet in four different soil types by using concrete-framed plots as follows: soil acidity (soil pH, exchange acidity y 1) and nitrification of fertilizer introduced by row application. Comparison of the value of the exchange acidity y 1 of the four soil types with the pH value adjusted to the same level (pH 5.1) revealed that the Humic Gray Upland soil displayed the highest y 1 value (y 1: 18.0), followed by the Humic Volcanogenous Regosol (y 1: 6.9), Haplic Brown Lowland soil (y 1: 5.3), and Low-humic Andosol (y 1: 2.2). Al release to the soil solution was considered to occur at soil pH values of 4.8 and lower except in the Low-humic Andosol. Al concentration in the soil solution of the Low-humic Andosol was substantially lower than that of the other soils. On the other hand, the soil pH value decreased temporarily by nitrification of the fertilizer introduced by row application, especially in the Humic Gray Upland soil. In this case, the soil pH value became lower than 4.8 for a time. At this pH level, Al release to the soil solution was assumed to occur. As described above, the soils displayed different properties in terms of soil acidity. In the four soils, although the growth of sugar beet was significantly related to both soil pH and exchange acidity y 1 values before sowing, these relations were not strictly valid. On the other hand, the linear correlation coefficients of the relationships between the growth of sugar beet (leaf length) and NO3-N content in rows were higher than those of the soil pH and exchange acidity y 1. No appreciable variation associated with the differences in the soil types was observed in this relation. Furthermore, the values of both soil pH and exchange acidity y 1 were closely related to the NO3-N content in rows and the relationship between the NO3-N content and y 1 value appeared to be somewhat closer than that with the soil pH. These closer relations had two important implications. Firstly, NO3-N content reflected the nitrogen nutrient conditions. NO3-N promoted the growth of sugar beet directly. Secondly, the NO3-N content was affected by the soil acidity, which is expressed by the value of the exchange acidity y 1. Low NO3-N content indicated indirectly the toxicity of soil acidity to sugar beet growth. It was thus suggested that in the present study, nitrification of the fertilizer expressed by the NO3-N content was a beneficial factor for the growth of sugar beet regardless of the soil types. Finally, to promote the nitrification of fertilizer and to minimize the Al toxicity enhanced by the decrease of the soil pH associated with nitrification, it is important to avoid low values for the soil pH.  相似文献   
66.
The objective of this study was to test for association of candidate single nucleotide polymorphisms (SNPs) with sow prolificacy reproductive traits, such as litter size, ovulation rate and lifetime performance, in gilts of a Large White pig population. Preliminary research on 25 animals selected from the high‐ and low‐performance groups of 347 animals with case‐control studies indicated that seven genes were associated with total number of piglets born (TNB). Six of the seven genes were associated with reproductive traits, including TNB, number of piglets born alive (NBA) and average weight of piglet weaning (AWW). A MBL2 SNP was significantly associated with TNB and NBA in first parity. A CFB SNP was associated with TNB in first parity. An ACE SNP was associated with TNB in first and second parities. An EGF polymorphism was associated with TNB, NBA and AWW in second parity. A KCNC2 polymorphism was significantly associated with TNB and NBA in second parity. A SLC22A5 SNP was associated with TNB and NBA in second parity. Six candidate SNPs were associated with TNB; the only exception was a PRKAG3 polymorphism. A candidate gene approach enables some of these polymorphisms to be used in genetic improvement programs based on marker‐assisted selection.  相似文献   
67.
68.
为了科学合理地确定指标权重,从而对灌区节水改造项目综合后评估作出理想的评价结果,在阐述基于离差平方和的综合赋权法和基于博弈论的综合赋权法原理的基础上,将这两种综合集成赋权法分别应用于关中洛惠渠等4个灌区的节水改造项目综合评估,发现两种综合赋权法得出的权重向量大小排序结果并不相同,但根据两种权重值计算的多个灌区综合评价值大小排序结果相同.对这一现象进行的进一步分析表明,两种综合集成赋权法的指导思想虽然不同,但其原理都是科学合理的.在确定灌区评价指标权重时,若为了对各灌区评价对象充分拉开档次,可选用基于离差平方和的综合赋权法,当希望尽可能保留各主客观权重值的信息时,可选用基于博弈论的综合赋权法.  相似文献   
69.
Defatted rice bran was extracted with water and subcritical water at 50-250 degrees C for 5 min. The highest extract yield was achieved at 200 degrees C, at which the maximum amounts of protein and carbohydrate were also obtained. The total phenolic and furfural contents, radical scavenging activity, and antioxidative activity for the autoxidation of linoleic acid increased with increasing treatment temperature. The bran extracts exhibited emulsifying activity except for the extract prepared at 250 degrees C, which was concomitant with the disappearance of its high-molecular-mass substances. The extract prepared at 200 degrees C also had the highest emulsion-stabilizing activity.  相似文献   
70.
以河豚鱼肉为原料,开发即食调味河豚鱼片。采用色泽、口感、气味和组织形态的感官评分作为评价指标,在糖用量、盐用量、酱油用量3个单因素试验的基础上,采用响应面法优化调味制备工艺;在最佳工艺制备条件下,以感官分值和质构特性为评价指标确定满足商业无菌要求的最佳杀菌时间。结果显示:在糖用量6.7%、盐用量4.0%、酱油用量4.2%、用水煮香料液补至100%的条件下,预测感官分值高达8.15,感官评分结果为8.40,与预测值接近;确定最佳杀菌时间是15 min。研究表明:即食调味河豚鱼片的制备工艺可行,并可为其他水产制品的深加工提供参考。  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