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   259篇
  免费   10篇
林业   14篇
农学   29篇
基础科学   4篇
  35篇
综合类   23篇
农作物   16篇
水产渔业   20篇
畜牧兽医   114篇
园艺   6篇
植物保护   8篇
  2022年   3篇
  2019年   2篇
  2018年   5篇
  2017年   7篇
  2016年   3篇
  2015年   7篇
  2014年   6篇
  2013年   10篇
  2012年   9篇
  2011年   7篇
  2010年   5篇
  2009年   4篇
  2008年   9篇
  2007年   6篇
  2006年   5篇
  2005年   7篇
  2004年   5篇
  2003年   7篇
  2002年   7篇
  2001年   5篇
  2000年   7篇
  1999年   4篇
  1998年   6篇
  1997年   3篇
  1994年   2篇
  1992年   3篇
  1991年   8篇
  1990年   4篇
  1989年   12篇
  1988年   8篇
  1987年   9篇
  1986年   4篇
  1985年   2篇
  1984年   4篇
  1982年   5篇
  1979年   4篇
  1978年   6篇
  1977年   3篇
  1976年   2篇
  1975年   3篇
  1974年   2篇
  1973年   5篇
  1972年   3篇
  1971年   2篇
  1970年   5篇
  1969年   8篇
  1968年   3篇
  1967年   7篇
  1966年   4篇
  1965年   3篇
排序方式: 共有269条查询结果,搜索用时 31 毫秒
91.
Twenty-three seeds of different botanical families growing in India were analysed for their protein content and amino acid compositions. They showed a wide variation in their total protein (8.0 to 42.7%). Some of them were comparable and some were even better than popular food legumes such as kidney bean and chick-pea in protein levels and amino acid compositions.  相似文献   
92.
Arsenic is known to have several phytotoxic effects and one of them is the reduction in chlorophyll content. Determination of chlorophyll content is often accomplished to assess the impact of most environmental stresses, as the pigment content is linked to the visual symptoms and photosynthetic plant productivity. Hence, the present investigation was undertaken to study the effect of As on chlorophyll synthesis with a view to gain some insights into the possible mechanism. Supply of 0.01 to 1.00 mM Na arsenate to the greening maize leaf segments decreased the chlorophyll content as well as chlorophyllase activity, but decline in former was more pronounced than latter at high concentration of As. Supply of arsenate also reduced total RNA, protein and acid soluble thiol content of the tissue. The inhibitory effect of As was less pronounced in the beginning i.e. upto 4 h, but became substantial with increasing time periods. Nitrate reductase activity was inhibited more strongly than chlorophyll formation and was induced only slightly by the supply of inorganic nitrogen in the presence of As. Inclusion of KNO3 had almost no effect on inhibitory effect of As on chlorophyll formation, while NH4Cl and NH4NO3 substantiated it. Percent decrease in chlorophyll content was reduced by 2-Oxoglutarate, glutamine, glycine and Na succinate, but it was increased by MgCl2 and remained unaltered by glutamate. Amongst the thio compounds tested, cysteine and 5,5′ dithio bis 2 nitro benzoic acid could overcome the toxic effect of As partially, while mercaptoethanol and dithiothreitol enhanced it and reduced glutathione had no effect. It is suggested that toxic effect of As on chlorophyll biosynthesis involves limited availability of δ-aminolevulinic acid and thiol modulation of proteins.  相似文献   
93.
Journal of Crop Science and Biotechnology - The identification of fertility restoration and genetic diversity of drought-tolerant breeding lines will be useful for the development of promising...  相似文献   
94.
ABSTRACT

Sariska Tiger Reserve (STR) is a virtual ecological island influenced by both anthropogenic pressures and a significant cattle population from the villages located there. The government has initiated voluntary relocation of villages, but this action has not yielded desired results as most of the residents depend on the surrounding forest for their livelihood. This study used a logit model to identify the influential factors that predict forest dependency. The results indicate that livestock population and the agricultural land per household as the two major determinants of dependency. Alternative sources of livelihood or vocational training may help in reducing villager’s forest dependency.  相似文献   
95.
Gluten strength is an important characteristic, determining the end product quality of durum wheat semolina. To identify the genetic basis of gluten strength in North Dakota durum cultivars, a doubled haploid population was developed from the cross of a weak gluten cultivar ‘Rugby’ and a strong gluten cultivar ‘Maier’. A framework linkage map consisting of 228 markers was constructed and used with phenotypic data on gluten strength (measured by sedimentation volume) to conduct single- and two-locus QTL analyses. Only one consistent QTL (QGs.ndsu-1B) contributing up to 90% of the phenotypic or 93% of the genotypic variation was detected on 1BS. No QTL × QTL or QTL × environment interactions were observed. The QGs.ndsu-1B was flanked by two DArT markers which were converted to STS markers and used along with SSR and EST-SSRs to develop a map of 1BS. QTL analysis delineated QGs.ndsu-1B in a 7.3 cM region flanked by an STS marker (STS-wPt2395) and a SSR marker (wmc85). The adapted background of this material and availability of PCR-based markers closely associated with this locus represent invaluable resources for marker-assisted introgression of gluten strength into other durum wheat varieties. A single QTL segregating in this population also makes it an ideal target for map-based cloning.  相似文献   
96.
蒸发是水循环的一个重要组成部分,对蒸发量的估算是对水资源和灌溉水量有效利用的一个重要手段。该研究旨在利用多元线性回归模型、多层感知器(MLP)和人工神经网络(ANN)模型模拟印度中央邦马尔瓦地区周蒸发量。利用4种不同天气变量组合训练神经网络模型。多元线性回归模型只将最高温和相对湿度作为输入值,但是模拟结果不令人满意。MLP模型采用的数据集包括最高和最低温度、风速和相对湿度,在训练和验证中都取得了比较好的结果。MLP模型可以用来模拟周开放式蒸发皿蒸发量,估算缺失数据,并可以作为替代模型以验证蒸发量测定值。降雨量数据并不能改善模型性能。   相似文献   
97.
A 2 × 2 × 2 factorial experiment was conducted to delineate the main effect of water soaking of plant ingredients, phytase, cellulase, and their interactions on the growth and digestive enzyme activities of Labeo rohita fingerlings. Two basal diets were prepared using water-soaked (S) or unsoaked (US) plant-based ingredients. Feed of US ingredients was supplemented with phytase (U kg−1) and cellulase (%) at the level of 0, 0 (Cus); 500, 0 (T1); 0, 0.2 (T2); 500, 0.2 (T3), and feed of S ingredients at 0, 0 (Cs); 500, 0 (T4); 0, 0.2 (T5), and 500, 0.2 (T6), respectively. Three hundred and sixty fingerlings were randomly distributed into eight treatments, each with three replicates. Soaking of the ingredients for 24 h significantly reduced the tannin content. However, feeding of S diets did not improve the fish growth. Highest performance was recorded in the T3 group. A significant interaction between dietary phytase and cellulase was observed for apparent net protein utilization. Tissue crude protein, ether extract, and ash content of the fingerlings were observed highest in the T3 group. Activities of amylase, protease, and lipase were recorded highest in the T3 group. Results suggested that soaking of plant-based ingredients reduces tannin content; however, growth and digestive enzyme activities of group fed soaked diet were not improved, possibly due to leaching of soluble nutrients. Probably, a shorter duration soaking may be effective in reducing tannin content and avoiding nutrients leaching.  相似文献   
98.
A field experiment entitled “nitrogen and vermicompost interaction on soil and leaf nutrient status of kinnow mandarin in vertisols of Jhalawar district” was conducted at the Fruit Research Farm, Department of Fruit Science, College of Horticulture and Forestry, Jhalawar (Rajasthan) during 2012–13 to study the effect of different levels of nitrogen and vermicompost on physico-chemical properties of soil and leaf micro and macro nutrient contents of Kinnow mandarin. The result indicated that application of T15 treatment i.e. nitrogen at 350 g/plant + vermicompost 20 kg/plant was found best with regard to improvement in soil physico-chemical properties like organic carbon content (0.44%), available nitrogen (N) (379.36 kgha?1), available phosphorus (P) (25.56 kgha?1), available potassium (393.29 kgha?1) and reduces electrical conductivity (0.34 dSm?1), soil pH (7.42) and calcium carbonate (CaCO3) content percentage (15.20) of soil.  相似文献   
99.
Ten‐week study was performed on Labeo rohita fingerlings (av. wt. 3.75 ± 0.06 g) to investigate the nature of compensatory growth. Fingerlings were deprived of food for 0 (control), 1 (D1), 2 (D2) or 3 (D3) weeks and refed to satiation for 5 weeks. The feed deprivation was carried out in D3 group on week 3, 4 and 5; D2 group on week 4 and 5; D1 group on week 5, and refeeding of all the groups were started from week 6 onwards. The D1 and D2 groups caught up in body weight with that of control fish within 2 weeks and 4 weeks of refeeding, respectively, but the D3 group had significantly (P < 0.05) lower body weight than the control after 5 weeks of refeeding. Higher growth efficiency was observed in all the feed deprived groups in the 1st week of refeeding only. Feed intake in D1 group became similar with the control after 5 weeks of refeeding, but the D2 and D3 groups were still hyperphagic when the experiment terminated. Thus, compensatory growth was due to hyperphagia and improved growth efficiency. In conclusion, complete compensatory growth was observed in L. rohita fingerlings after feed deprivation of 1 and 2 weeks.  相似文献   
100.
Embelia ribes (common name, Vidanga) is extensively used in traditional system of medicine for treatment of various disorders. It is described in Ayurveda, as a powerful anthelmintic, antifertility and antihyperlipidemic agent. The present study was undertaken to investigate modulatory effect of 6 weeks' chronic oral administration of E. ribes ethanolic extract on diabetes mellitus induced by a diabetogen, streptozotocin (STZ) with special reference to changes in glucose levels, glycated haemoglobin status and cardiac toxicity. STZ treatment (40 mg/kg iv) resulted in significant increase in blood glucose levels, glycated haemoglobin levels, heart rate (HR) and systolic blood pressure (SBP). Oral administration of E. ribes ethanolic extract in dose of 100 mg/kg and 200 mg/kg significantly reduced the levels of blood glucose, glycated haemoglobin, heart rate (HR) and systolic blood pressure (SBP) in animals when compared with diabetic rats.  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