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   57篇
  免费   2篇
林业   3篇
农学   7篇
  8篇
综合类   2篇
农作物   7篇
水产渔业   5篇
畜牧兽医   23篇
园艺   2篇
植物保护   2篇
  2021年   1篇
  2020年   1篇
  2019年   3篇
  2018年   1篇
  2017年   1篇
  2016年   1篇
  2014年   2篇
  2013年   5篇
  2012年   3篇
  2011年   4篇
  2009年   1篇
  2008年   1篇
  2007年   3篇
  2006年   4篇
  2002年   1篇
  2000年   1篇
  1997年   1篇
  1996年   1篇
  1994年   1篇
  1991年   2篇
  1983年   2篇
  1982年   1篇
  1980年   1篇
  1979年   3篇
  1975年   1篇
  1974年   1篇
  1973年   2篇
  1970年   3篇
  1969年   3篇
  1968年   2篇
  1965年   1篇
  1959年   1篇
排序方式: 共有59条查询结果,搜索用时 15 毫秒
1.
2.
Monocrotophos (MCP) is one of the organophosphate pesticides extensively used in agriculture and animal husbandry. The present study reports the effects of sub‐lethal concentrations of MCP on gonadosomatic index (GSI), gonadal histology and breeding fitness of the fish Anabas testudineus. The fish were exposed to three sub‐lethal concentrations of monocrotophos (T1: 3.5 mg/L, T2: 5.3 mg/L and T3: 10.6 mg/L) for 45 days with 12 fish (males and females in equal numbers) in each tank, and one group was kept as control (C) without any treatment. GSI decreased in all treatment groups in comparison with control. Significant decrease in fertilization and hatching rate was observed at all concentrations in comparison with control on 15, 30 and 45 days of monocrotophos exposure. The decreased vitellogenesis, disruption of follicular wall and oocyte atresia were observed in all the treated females at 30 and 45 days of exposure. Rupture of seminiferous tubules was noticed in all the treated males irrespective of exposure periods. The results thus indicated that monocrotophos could deleteriously impact the gonadal structure and function in A. testudineus, which could seriously impact the reproductive success of the animal.  相似文献   
3.
4.
5.
Brassica juncea , cv. Pusa Bold, and Brassica campestris , cv. Pusa Kalyani, were raised under field conditions with varying levels of N fertilization, i.e. 0, 40, 80 and 120 kg N ha−1. Changes in dry matter accumulation in various plant parts as influenced by N supply were measured throughout the crop ontogeny. N supply up to 120 kg had an increasing effect on the growth of leaves, stem and pods during the entire period till maturity. Analysis on the assimilate distribution pattern revealed that 84–87% of the total was accumulated during the post-flowering phase. Dry matter partitioning profile during the ontogeny indicated that about 72–83 % of the total DM was accumulated in the leaves, while 17–28 % in the stem, in the preflowering phase. This trend was found nearly opposite during the postflowering phase. At maturity, however, stem and pods accounted for nearly equal amounts of dry matter accumulation. Among the genotypes, Pusa Bold recorded significantly higher DM accumulation and seed yield over Pusa Kalyani which, on the other hand, exhibited a better assimilate-partioning ability than the former. Nitrogen levels had a favourable effect on LAI, LAD and CGR in both genotypes. Highly significant correlations were obtained between seed yield vs. LAI, LAD and CGR. N fertilization up to 120 kg ha−1 was found beneficial in enhancing growth and yield of rapeseed-mustard.  相似文献   
6.
Brasisca Juncea , cv. Pusa Bold, and B. campestris , cv. Pusa Kalyani, were raised under field conditions with varying levels of N supply from 0–120 kg ha-1. The production profile of branches and pods thereon was measured, per unit area basis, throughout the crop ontogeny. At maturity, data on the yield contributing characters, viz. pod dry weight, pod number, seed number per pod, 1000 seed weight, seed wall ratio and seed yield in different order branches, was recorded.
The branching pattern and the number of pods produced on different order branches, in the two species, was favourably modified by the increasing levels of N supply. Primary and secondary branches contributed to the seed yield to an extent of 80 % of the total yield. Nitrogen treatment had no significant effect on 1000 seed weight. B. juncea exhibited significantly higher yield over B. campestris. N supply up to 120 kg ha -1 linearly increased seed yield in both the species. However, it exerted a negative effect too partitioning of assimilates from pod wall to seed. The study indicated that rapeseed-mustard, grown under short winter-season environment with adequate soil moisture, has the potential for higher N-fertilizer optima exceeding 120 kg ha -1.  相似文献   
7.
Summary Twenty nine strains of vegetable amaranth (Amaranthus tricolor were grown for two successive seasons to study different selection parameters for foliage yield and its nine contributing morphological and quality traits. The strains AV-38 (5.06 kg/plot) and AV-31 (5.04 kg/plot) recorded highest foliage yield, followed by AV-30 (4.78 kg/plot) and AV-23 (4.70 kg/plot). The protein and carotenoid content averaged 1.24 ± 0.03 mg/100 mg and 0.83 ± 0.02 mg/g respectively. The leaves of A. tricolor also have considerable quantities of ascorbic acid (112.33 ± 5.00 mg/100 g) and fibre (8.39 ± 0.10%). The mean of individual cuttings for plant height, leaf size, stem diameter, foliage yield, protein, ascorbic acid and fibre content increased with successive cuttings till third cutting and thereafter showed a decline. Genotypic coefficient of variation (GCV) values ranged from 6.80 to 28.25%. However, the fibre content, branches/plant, leaves/plant, plant height and stem diameter showed lowest values of GCV. The values of heritability estimates were high for all the traits in all the cuttings as well as on pooled basis and ranged from 0.89 for branches/plant to 0.98 for foliage yield. Highest expected genetic advance was noticed for ascorbic acid (57.48%), followed by foliage yield (48.30%) and leaf size (29.51%).  相似文献   
8.
Ellagic acid, a plant-derived polyphenol, inhibits gamma-radiation (hydroxyl radical) induced lipid peroxidation in rat liver microsomes in a dose- and concentration-dependent manner. Its antioxidant capacity has been estimated using the 1,1-diphenyl-2-picrylhydrazyl radical assay. To understand the actual mechanisms involved in antioxidant activity and the free radical scavenging ability,a nanosecond pulse radiolysis technique has been employed. The rate constants for the reactions of several reactive oxygen species and reactive nitrogen species such as hydroxyl, peroxyl, and nitrogen dioxide radicals have been found to be in the range of 10(6)-10(9) M(-1) s(-1). The ellagic acid radicals have been characterized by the absorption spectra and decay kinetics. Studies on the reactions of ellagic acid with the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) radical and the radicals of ellagic acid with ascorbate have been used to estimate its one-electron reduction potential. Ellagic acid has also been found to be a good scavenger of peroxynitrite. Using stopped-flow reaction analyzer with absorption detection, the rate constant for this reaction has been determined to be 3.7 x 10(3) M(-1) s (-1). The electron spin resonance spectra of the oxidized ellagic acid radicals have been recorded by horseradish peroxidase and hydrogen peroxide method.  相似文献   
9.
Detailed karyotypic studies have been done in 20 wild and cultivated taxa of Chenopodium, which belong to three ploidy levels 2x, 4x and 6x. C. quinoa (4x) shows minor but consistent differences in the arm ratio of various chromosomes within the complements of different accessions. The chromosomes can be arranged in 18 pairs that suggest allotetraploid nature. The karyotype of C. berlandieri subsp. nuttalliae (4x) is basically similar to that of C. quinoa. C. bushianum (6x) is distinctly different from the above two species in showing highest ratio between longest and shortest chromosomes. C. album complex is characterized by consisting of 2x, 4x and 6x cytotypes. Marked karyotypic differentiation is seen even among various 2x accessions. The 4x cytotype has a more asymmetrical karyotype as compared with 2x and 6x cytotypes. The karyotypic differences are also apparent between two 6x cytotypes studied. C. strictum (6x) and C. giganteum (6x) show close similarity to 6x types of C. album.  相似文献   
10.
Twenty nine germplasm lines of Chenopodium quinoa and two of Chenopodium berlandieri subsp. nuttalliae were evaluated for 12 morphological and 7 quality traits for two test seasons. The 19 traits were analyzed for cluster and principal component analysis. The first four PCs contributed 78.70 % of the variability among the germplasm lines. The first PC accounted for 39.5% of the variation and had inflorescence/plant, plant height and stem diameter as the traits with largest coefficients, all with positive sign. The characters with greatest positive weight on PC2 were days to maturity (0.309), inflorescence length (0.260) and branches/plant. All the germplasm lines were grouped into six clusters based on average linkage method. Cluster III had high values for seed yield and most of the quality traits but showed a small seed size. The dendrogram separated the two lines of C. berlandieri subsp. nuttalliae from the quinoa lines.  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