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   419篇
  免费   14篇
林业   37篇
农学   24篇
基础科学   6篇
  69篇
综合类   18篇
农作物   45篇
水产渔业   29篇
畜牧兽医   163篇
园艺   8篇
植物保护   34篇
  2023年   1篇
  2022年   6篇
  2021年   7篇
  2020年   4篇
  2019年   6篇
  2018年   15篇
  2017年   8篇
  2016年   15篇
  2015年   14篇
  2014年   12篇
  2013年   28篇
  2012年   40篇
  2011年   45篇
  2010年   20篇
  2009年   18篇
  2008年   23篇
  2007年   20篇
  2006年   18篇
  2005年   14篇
  2004年   18篇
  2003年   15篇
  2002年   13篇
  2001年   13篇
  2000年   9篇
  1999年   9篇
  1998年   4篇
  1994年   2篇
  1993年   1篇
  1992年   3篇
  1991年   4篇
  1990年   2篇
  1989年   4篇
  1986年   1篇
  1985年   2篇
  1983年   3篇
  1982年   2篇
  1981年   1篇
  1980年   2篇
  1979年   1篇
  1975年   2篇
  1973年   1篇
  1967年   2篇
  1966年   1篇
  1965年   1篇
  1964年   1篇
  1963年   1篇
  1961年   1篇
排序方式: 共有433条查询结果,搜索用时 15 毫秒
151.
Summary

Pomaces obtained during the production of cloudy or clear juice from scab-resistant apple cultivars (28 harvested in 2006, and 23 harvested in 2007) were studied as a source of nutritionally important components. It was shown that the average yield of pomace during the production of cloudy juice was 6.4% (w/w), and 4.9% (w/w) for clear juice pressing. The average total dietary fibre (TDF) contents were 48.4% (w/w) and 52.4% (w/w) for cloudy and clear juice pomaces, respectively. Ten pomaces from cloudy apple juice production, and 12 obtained from clear juice production, contained ≥ 2,000 mg kg?1 of polyphenols.‘Ariwa’ and ‘Rajka’ are apple cultivars suitable for juice production and their pomaces are characterised by having high contents of TDF [50.9% (w/w) and 51.1% (w/w), respectively], with aboveaverage polyphenol and quercetin glycoside concentrations. The mean contents of quercetin glycosides for pomaces from all apple cultivars was 994 mg kg?1 after clear juice production, and 908.2 mg kg?1 after cloudy juice production. ‘Topaz’, which became a popular commercial apple cultivar in Europe, was the best source of health-promoting components. Its pomace was the richest source of polyphenols among all 28 cultivars studied. It contained ≥ 2,000 mg kg?1 quercetin glycosides in both its clear and cloudy juice pomaces.  相似文献   
152.
Synthetic and persistent endocrine disrupting chemicals (EDCs) such as 17α-ethinylestradiol (EE2) have been frequently detected in the effluent of wastewater treatment plants and induce hazards to humans and wildlife. In this study, biogenic Mn oxides were tested for the removal of EE2, and factors affecting the reaction were also investigated. The biogenic Mn oxides produced by Pseudomonas putida strain MnB1 were nano-sized and poorly crystallized particles. A concentration of 7.9 mg l−1 biogenic Mn oxides showed 87% EE2 (1 mg l−1) removal efficiency in 2 h, which confirms the excellent potential of biogenic Mn oxides for removal of estrogens. EE2 removal was enhanced at high Mn oxide doses and at low pH. Co-existing heavy metals significantly inhibit EE2 removal, due to their competition for the reactive sites of biogenic Mn oxides. Humic acid (HA) also obstructed EE2 removal, but the adverse effect was alleviated as HA concentration increased, possibly due to the formation of soluble complexes with the released Mn2+, of which adsorption onto Mn oxides reduces surface reactive sites.  相似文献   
153.
Due to slow growth and weakness of the first development of chickpea (Cicer arietinum L.) plant could not combatted with weeds and easily get caught up by Ascochyta blight (Ascochyta rabiei (Pass) Labr.) disease; esp. under the late sowing and semi-arid conditions, due to effect of biotic and abiotic stress factors, significant yield losses could be arised. To be able to avoid from them is only possible to accelerate the first development of this crop. So, one of the best solutions is to use of "soil conditioner" chemical compounds such as HA at optimum dose. With this aim, it was established in order to find out the optimum dose range of HA. Three doses (D0 = 0 g, D1 = 100 g and D2 = 200 g), four varieties (V1 = Er-99, V2 = G?k?e, V3 = ILC-482 and V4 = Australia) and five yield components Plant Height (PH), First pod height (FPH), Number of Branches per Plant (NBP), Number of Pods per Plant (NPP) and Number of seeds per pod (NSP) were investigated. Obtained results are: Recommended (Optimum) HA doses and interactions were ranged and found as (V4 > V2 = V3 > V1); (D2 > D0 = D1); (D1 x V4) for the PH and FPH, (D2 x V3) for the NBP and (D1 x V3) for the NPP, respectively. It was concluded that when the recommended HA dose applied, it was seen that the first development has been clearly accelerated and increased under the semi-arid conditions in terms of investigated traits and cultivars.  相似文献   
154.
Juveniles of the fan mussel Pinna nobilis were collected in Mali Ston Bay from October to December 2006. Cages with juveniles were placed at three depths: 1, 3 and 5 m. At the end of a 2‐year growth period at 1 m depths, the average length was 244.1 ± 22.9 mm, at 3 m depths, specimens averaged 244.0 ± 25.3 mm, and at 5 m depths, the average length was 231.1 ± 22.5 mm. The average monthly growth of shell length for the total experimental period was 8.7 ± 5.3, 8.4 ± 4.5 and 7.6 ± 4.4 mm, at 1, 3 and 5 m depths respectively.  相似文献   
155.
Plant responses to water deficit need to be monitored for producing a profitable crop as water deficit is a major constraint on crop yield. The objective of this study was to evaluate physiological responses of cotton (Gossypium hirsutum) to various environmental conditions under limited water availability using commercially available varieties grown in South Texas. Soil moisture and variables of leaf gas exchange were measured to monitor water deficit for various varieties under different irrigation treatments. Lint yield and growth variables were also measured and correlations among growth parameters of interest were investigated. Significant differences were found in soil moisture, leaf net assimilation (An), stomatal conductance (g), transpiration rate (Tr), and instantaneous water use efficiency (WUEi) among irrigation treatments in 2006 while no significant differences were found in these parameters in 2007. Some leaf gas exchange parameters, e.g., Tr, and leaf temperature (TL) have strong correlations with An and g. An and WUE were increased by 30–35% and 30–40%, respectively, at 600 μmol (CO2) m−2 s−1 in comparison with 400 μmol (CO2) m−2 s−1. Lint yield was strongly correlated with g, Tr, WUE, and soil moisture at 60 cm depth. Relative An, Tr, and TL started to decrease from FTSW 0.3 at 60 cm and FTSW 0.2 at 40 cm. The results demonstrate that plant water status under limited irrigation management can be qualitatively monitored using the measures of soil moisture as well as leaf gas exchange, which in turn can be useful for describing yield reduction due to water deficit. We found that using normalized An, Tr, and TL is feasible to quantify plant water deficit.  相似文献   
156.
Longline surveys have been conducted in the Northwest Pacific Ocean from 2000 to 2014 using chartered commercial longline vessels. Each year, two cruises were conducted offshore of northeastern Japan from mid‐April to mid‐June. For each longline set during the surveys, onboard scientists collected detailed biological information about the species caught, such as the size and sex, and recorded the catch numbers for all species. Blue shark (Prionace glauca) and shortfin mako (Isurus oxyrinchus) have eurythermal distributions, but the application of a generalized additive model (GAM) showed that the sea surface temperatures (SSTs) at catch sites positive for shortfin mako were warmer than those for blue shark. On the basis of the GAM, the probabilities of occurrence of both sharks differed by size category: small sharks had a narrower SST range than that of large sharks. Most catches of both sharks were juveniles, and the nominal catch rate of blue shark was more than 10 times that of shortfin mako. The standardized catch per unit effort (CPUE) for both species was calculated using a generalized linear model (GLM) with negative binomial errors, or a delta‐lognormal GLM. The standardized CPUE for blue shark in the second quarter of the year peaked in the mid‐2000s and then decreased, but it has been increasing since 2012. The CPUE for shortfin mako in the second quarter generally increased, with fluctuations.  相似文献   
157.
158.
159.
160.
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