全文获取类型
收费全文 | 187篇 |
免费 | 17篇 |
国内免费 | 1篇 |
专业分类
林业 | 8篇 |
农学 | 8篇 |
基础科学 | 1篇 |
38篇 | |
综合类 | 27篇 |
农作物 | 14篇 |
水产渔业 | 27篇 |
畜牧兽医 | 59篇 |
园艺 | 9篇 |
植物保护 | 14篇 |
出版年
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 9篇 |
2018年 | 9篇 |
2017年 | 5篇 |
2016年 | 2篇 |
2015年 | 5篇 |
2014年 | 5篇 |
2013年 | 12篇 |
2012年 | 13篇 |
2011年 | 14篇 |
2010年 | 8篇 |
2009年 | 12篇 |
2008年 | 16篇 |
2007年 | 18篇 |
2006年 | 8篇 |
2005年 | 7篇 |
2004年 | 9篇 |
2003年 | 13篇 |
2002年 | 13篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1982年 | 1篇 |
1974年 | 1篇 |
1952年 | 1篇 |
排序方式: 共有205条查询结果,搜索用时 312 毫秒
91.
92.
Pamela Lithgow Haru Takamatsu Dirk Werling Linda Dixon Dave Chapman 《Veterinary microbiology》2014,168(2-4):413-419
The expression of surface markers on African swine fever virus (ASFV) infected cells was evaluated to assess their involvement in infection. Previous findings indicated CD163 expression was correlated with ASFV susceptibility. However, in this study the expression of porcine CD163 on cell lines did not increase the infection rate of these cells indicating other factors are likely to be important in determining susceptibility to infection. On adherent porcine bone marrow (pBM) cells the expression of CD45 was strongly correlated with infection. CD163 and CD203a expression correlated at intermediate levels with infection, indicating cells expressing these markers could become infected but were not preferentially infected by the virus. Most of the cells expressing MHCII were infected, indicating that they may be preferentially infected although expression of MHCII was not essential for infection and a large percentage of the infected cells were MHCII negative. CD16 showed a marked decrease in expression following infection and significantly lower levels of infected cells were shown to express CD16. Altogether these results suggest CD163 may be involved in ASFV infection but it may not be essential; the results also highlight the importance of other cell markers which requiring further investigation. 相似文献
93.
Phosphate fertilizers are recognized as a potential source of elements that could contribute to soil pollution. The objective of this study was to determine the extent to which use of phosphate fertilizer in the past had resulted in an increase in heavy‐metal content in Irish soils. Samples were taken from a long‐term replicated (six replicates of 0.18 ha each) plot experiment with grazing cattle. Phosphate as superphosphate had been applied at two rates, 0 and 930 kg ha–1 total P, over a 31 y period. Phosphorus, pH, soil organic matter, Cd, F, Mg, and Zn were measured in 0–10 and 10–20 cm soil layers in addition to extractable P and Mg (Morgan's solution) and Zn (0.5M EDTA). Increases in the phosphate‐enriched soil were significant at p < 0.05 except for F at both soil layers and for Cd at the 10–20 cm layer (p < 0.1) Recoveries for P, Cd, and F were in fair agreement with application. High recoveries of total Mg and Zn were encountered which could not readily be explained. These increases were paralleled by increases in extractable‐soil‐test values for these elements. Accumulation in soil of P over the period was such as to now necessitate little application of this element to soil for the near future. At the same time, increase in soil Cd was small, little more than 0.05 mg kg–1 in soil, although it amounted to a sizable proportion of Cd in the soil. Similarly, increases in other elements, although real, would not lead to major concerns at the present time. 相似文献
94.
用加拿大双低菜粕部分替代TMR中豆粕对奶牛产奶量和乳成分的影响 总被引:1,自引:0,他引:1
中国是世界上最大的油菜籽生产国,近几年来每年的生产量在1100~1200 万t(Huang 等,2005;Deng,2005;Qin and Zhou,2005;Wang,2004).这就意味着每年有600~700 万t的菜粕和菜饼的产量.普通菜粕常作为水产动物的饲料原料(添加10%~40%),但是在猪、鸡、肉牛和奶牛日粮中常被限制利用. 相似文献
95.
Summary Two studies, one with four cultivars grown at four locations during 1989 to 1993, and the second with a transgenic and its non-transformed parent cultivar grown at three locations for three years, were undertaken to explore the variation in total flavonoid content of flaxseed (Linum usitatissimum). Results of the analyses of variance for the first study showed significant cultivar as well as environmental effect on flavonoid content. Cultivar NorLin displayed the highest flavonoid content across the sites with a mean of 71 mg/100 g, and Omega, a yellow-seeded flaxseed cultivar, the lowest with a mean of 35 mg/100 g. There was no significant difference between a transgenic flaxseed and its non-transformed parent for total flavonoid content except for one location in 1991. Flavonoid content was inversely related to the protein content and there was a weak positive correlation between flavonoid and oil levels. 相似文献
96.
Antimony (Sb) and Copper (Cu) are two metals of major concern in sewage sludge. Antimony because its use in society is increasing and this might lead to increased Sb concentrations in sludge. Copper because its total volume in use in society is large and because of corrosion from water pipes it is most difficult to reduce the Cu concentrations in sludge. Fresh digested sewage sludge was spiked with Cu or Sb and the sludge was cultivated with oat (Avena sativa), lettuce (Lactuca sativa) or radish (Raphanus sativus). Elutriates from the cultivated sludge were tested for toxicity with Lemna minor (7-d growth) and Daphnia magna (48 h immobility). Before cultivation the elutriates were toxic to Lemna and Daphnia due to high concentrations of ammonia (NH3) and nitrite (NO2 -). Cultivation decreased the concentrations of both NH3 and NO2 -, thereby reducing the impact of these compounds in the toxicity tests. Cultivation also decreased the metal concentrations and pH. Daphnia magna was the most sensitive test organism in this study with a 48 h EC50 of 1130 mg Cu kg-1 dry wt and 5 mg Sb kg-1 dry wt in elutriates from sludge cultivated with oat. In sludge cultivated with radish the 48 h EC50 was 1700 mg Cu kg-1 dry wt and 22 mg Sb kg-1 dry wt. The effect of Cu could be predicted by pH and Cu concentrationin the elutriate, but the effect of Sb could not solely be explained by its concentration in the elutriate. 相似文献
97.
The distribution of cadmium- (Cd-) binding components in flaxseed (cultivar NorMan) containing 0.526 ppm (ng/mg) Cd was investigated. Proteins extracted from dehulled, defatted flaxseed were fractionated by anion-exchange and size-exclusion chromatography. The contents of Cd and other metals, UV/visible spectral characteristics, and amino acid compositions of these fractions were analyzed. Over 66% of the eluted Cd was recovered by 0.1 M NaCl elution from DEAE-Sephacel, in a thiol-rich fraction representing only 7% of the extracted proteins. Sephadex G50 size-exclusion chromatography of this 0.1 M NaCl fraction concentrated most of the Cd in a low-molecular-weight peak eluting at V(t). About 72% of the extracted flaxseed proteins eluted from DEAE-Sephacel at 0.25 M NaCl and contained only 25% of the eluted Cd. Because the major Cd-binding fraction is a minor constituent of flaxseed, these results indicate the potential to isolate flaxseed's major storage protein with a low Cd content. 相似文献
98.
Boner PL Liu DD Feely WF Wisocky MJ Wu J 《Journal of agricultural and food chemistry》2003,51(13):3753-3759
A method was developed and validated to determine 5-hydroxyflunixin in raw bovine milk using liquid chromatography tandem mass spectrometry (LC/MS/MS). The mean recovery and percentage coefficient of variation (%CV) of 35 determinations for 5-hydroxyflunixin was 101% (5% CV). The theoretical limit of detection was 0.2 ppb with a validated lower limit of quantitation of 1 ppb and an upper limit of 150 ppb. Accuracy, precision, linearity, specificity, ruggedness, and storage stability were demonstrated. A LC/MS/MS confirmatory method using the extraction steps of the determinative method was developed and validated for 5-hydroxyflunixin in milk from cattle. Briefly, the determinative and confirmatory methods were based on an initial solvent (acetone/ethyl acetate) precipitation/extraction of acidified whole milk. The solvent precipitation/extraction effectively removed incurred ((14)C) residues from milk samples. The organic extract was then purified by solid phase extraction (SPE) using a strong cation exchange cartridge (sulfonic acid). The final SPE-purified sample was analyzed using LC/MS/MS. The methods are rapid, sensitive, and selective and provide for the determination and confirmation of 5-hydroxyflunixin at the 1 and 2 ppb levels, respectively. 相似文献
99.
Bacon D 《Science (New York, N.Y.)》2007,317(5846):1876-1877
100.
Finnerty JR Pang K Burton P Paulson D Martindale MQ 《Science (New York, N.Y.)》2004,304(5675):1335-1337
Over 99% of modern animals are members of the evolutionary lineage Bilateria. The evolutionary success of Bilateria is credited partly to the origin of bilateral symmetry. Although animals of the phylum Cnidaria are not within the Bilateria, some representatives, such as the sea anemone Nematostella vectensis, exhibit bilateral symmetry. We show that Nematostella uses homologous genes to achieve bilateral symmetry: Multiple Hox genes are expressed in a staggered fashion along its primary body axis, and the transforming growth factor-beta gene decapentaplegic (dpp) is expressed in an asymmetric fashion about its secondary body axis. These data suggest that bilateral symmetry arose before the evolutionary split of Cnidaria and Bilateria. 相似文献