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   117篇
  免费   10篇
林业   11篇
农学   2篇
  24篇
综合类   5篇
农作物   3篇
水产渔业   13篇
畜牧兽医   54篇
植物保护   15篇
  2022年   5篇
  2021年   4篇
  2020年   3篇
  2017年   6篇
  2016年   4篇
  2015年   5篇
  2014年   5篇
  2013年   12篇
  2012年   5篇
  2011年   9篇
  2010年   9篇
  2009年   4篇
  2008年   6篇
  2007年   9篇
  2006年   8篇
  2005年   6篇
  2004年   5篇
  2003年   8篇
  2002年   3篇
  2001年   3篇
  2000年   3篇
  1999年   1篇
  1998年   3篇
  1985年   1篇
排序方式: 共有127条查询结果,搜索用时 15 毫秒
121.
The recurrence of estrus and fertility after removal of a subcutaneous chlormadinone acetate implant (CMA-I) administered to prevent estrus for 4 years, was investigated in 8 female dogs and the results compared with those for 4 untreated female dogs (control group). The sex hormones present during the estrous cycle were also investigated. There were no significant differences in the estrous cycle after removal of the implant between the CMA-I-treated group and the control group. However, although conception was achieved after mating and no uterine diseases developed in the control group, only 5 (4 dogs, 41.7%) of the 12 cases (6 dogs) in which mating took place at the second to fourth estrus after the removal of CMA-I resulted in pregnancy in the CMA-I-treated group. Furthermore, 6 (75.0%) of the 8 dogs in the CMA-I-treated group developed uterine diseases including pyometra or hydrometra. There were no significant differences in plasma progesterone, LH and prolactin levels between the non-pregnant and pregnant dogs in the CMA-I-treated group or control group. These results suggest that long-term implantation of CMA-I affects fertility after the implant is removed.  相似文献   
122.
Cucumber mosaic virus (CMV) was isolated from a mosaic diseased plant of Eucharis grandiflora. The virus caused mosaic symptoms on leaves and slight distortion of flower petals in E. grandiflora by either mechanical or aphid inoculation. The virus was identified as a strain of CMV subgroup I from its biological and serological characteristics.  相似文献   
123.
124.
125.
The composition of concentration ratios of 19 inorganic elements to Mg (hereinafter referred to as 19-element/Mg composition) was applied to chemometric techniques to determine the geographic origin (Japan or China) of Welsh onions (Allium fistulosum L.). Using a composition of element ratios has the advantage of simplified sample preparation, and it was possible to determine the geographic origin of a Welsh onion within 2 days. The classical technique based on 20 element concentrations was also used along with the new simpler one based on 19 elements/Mg in order to validate the new technique. Twenty elements, Na, P, K, Ca, Mg, Mn, Fe, Cu, Zn, Sr, Ba, Co, Ni, Rb, Mo, Cd, Cs, La, Ce, and Tl, in 244 Welsh onion samples were analyzed by flame atomic absorption spectroscopy, inductively coupled plasma atomic emission spectrometry, and inductively coupled plasma mass spectrometry. Linear discriminant analysis (LDA) on 20-element concentrations and 19-element/Mg composition was applied to these analytical data, and soft independent modeling of class analogy (SIMCA) on 19-element/Mg composition was applied to these analytical data. The results showed that techniques based on 19-element/Mg composition were effective. LDA, based on 19-element/Mg composition for classification of samples from Japan and from Shandong, Shanghai, and Fujian in China, classified 101 samples used for modeling 97% correctly and predicted another 119 samples excluding 24 nonauthentic samples 93% correctly. In discriminations by 10 times of SIMCA based on 19-element/Mg composition modeled using 101 samples, 220 samples from known production areas including samples used for modeling and excluding 24 nonauthentic samples were predicted 92% correctly.  相似文献   
126.
Land use and landscape changes, which have much effect on local biodiversity, are driven primarily by socioeconomic forces. Understanding these forces is important for preservation of current biodiversity. In this study, we clarified the socioeconomic forces that have brought about changes in the forest landscape around the Ogawa Forest Reserve in the southern Abukuma Mountains, Japan, by interviewing local residents and reviewing local historical documents. Furthermore, we reconstructed past forest landscapes and quantified the changes that have occurred from the beginning of the twentieth century until the present by use of old land-use maps and past aerial photographs. The use of forest resources has dramatically changed during the past hundred years, and it can be divided into three periods corresponding to the level of economic development. The main landscape has changed significantly from one mainly composed of expansive grasslands and broad-leaved forests into a mosaic of fragmented secondary forests and coniferous plantations. These landscape changes reflect shifts in both the use of forest resources by local residents and the management of the national forests. Clarifying temporal–spatial landscape changes by understanding the historical relationship between humans and the landscape provides useful information for optimizing conservation and management planning.  相似文献   
127.
The effects of environmental temperature on gelatinization properties and amylopectin structures of wheat endosperm starch were examined by isolating starches from four wheat cultivars matured in growth chambers at daytime temperatures of 15, 20, 25, or 30°C. Kernel weight and starch content per kernel were reduced by high maturation temperature. Amylose content showed no significant change at high maturation temperature in some cultivars; in other cultivars, there was a slight increase. Principal component analysis of data on relative peak areas of debranched amylopectin showed that amylopectin from wheat grown at a lower temperature had a greater proportion of shorter chains. Amylopectin branch chains were classified into three groups based on the correlation coefficients between the data of branch chain length distribution and principal component scores, degree of polymerization (DP) of 6–12, DP 13–34, and DP ≥ 35. The gelatinization temperature of starches increased markedly at a higher maturation temperature, with increases exceeding 10°C at high maturation temperatures. Gelatinization properties correlated significantly with amylopectin chain length distribution.  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