全文获取类型
收费全文 | 338篇 |
免费 | 14篇 |
专业分类
林业 | 23篇 |
农学 | 8篇 |
基础科学 | 5篇 |
62篇 | |
综合类 | 76篇 |
农作物 | 18篇 |
水产渔业 | 14篇 |
畜牧兽医 | 106篇 |
园艺 | 6篇 |
植物保护 | 34篇 |
出版年
2023年 | 5篇 |
2022年 | 2篇 |
2021年 | 13篇 |
2020年 | 11篇 |
2019年 | 12篇 |
2018年 | 12篇 |
2017年 | 9篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 14篇 |
2013年 | 15篇 |
2012年 | 16篇 |
2011年 | 22篇 |
2010年 | 13篇 |
2009年 | 13篇 |
2008年 | 21篇 |
2007年 | 29篇 |
2006年 | 20篇 |
2005年 | 11篇 |
2004年 | 16篇 |
2003年 | 13篇 |
2002年 | 21篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1981年 | 4篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1967年 | 2篇 |
1943年 | 1篇 |
排序方式: 共有352条查询结果,搜索用时 265 毫秒
1.
James W. Wynne Chris Stratford Joel Slinger Francisca Samsing Megan Rigby Russell McCulloch Petra Quezada-Rodriguez Richard S. Taylor 《Journal of fish diseases》2020,43(1):39-48
Hydrogen peroxide (H2O2) is a commonly used treatment for a range of parasitic diseases of marine finfish, including amoebic gill disease (AGD). While this treatment is partially effective at reducing parasite load, H2O2 can have detrimental effects on the host under certain conditions. Treatment temperature and dose concentration are two factors that are known to influence the toxicity of H2O2; however, their impact on the outcome of AGD treatment remains unclear. Here, we investigated the effects of treatment temperature (8, 12 or 16°C) and dose concentration (750, 1,000, 1,250 mg/L) on the efficacy of H2O2 to treat AGD. We demonstrated that a 20-min bath treatment of H2O2 at all doses reduced both parasite load and gross gill score significantly. Parasite load and gross gill score were lowest in the 1,000 mg/L treatment performed at 12°C. At the high dose and temperature combinations, H2O2 caused moderate gill damage and a significant increase in the plasma concentration of electrolytes (sodium, chloride and potassium). Taken together, our study demonstrates that higher H2O2 treatment temperatures can adversely affect the host and do not improve the effectiveness of the treatment. 相似文献
2.
Clayton T Larue Joel E Ream Xuefeng Zhou Farhard Moshiri Arlene Howe Michael Goley Oscar C Sparks Steven T Voss Erin Hall Christine Ellis Janice Weihe Qungang Qi Daniela Ribeiro Xiaoping Wei Shirley Guo Artem G Evdokimov Marguerite J Varagona James K Roberts 《Pest management science》2020,76(3):1031-1038
3.
4.
Alfredo Manicardi Laura Scarabel Josep María Llenes José María Montull María Dolores Osuna Joel Torra Farré Andrea Milani 《Pest management science》2023,79(12):4886-4896
BACKGROUND
Amaranthus palmeri is an aggressive annual weed native to the United States, which has become invasive in some European countries. Populations resistant to acetolactate synthase (ALS) inhibitors have been recorded in Spain and Italy, but the evolutionary origin of the resistance traits remains unknown. Bioassays were conducted to identify cross-resistance to ALS inhibitors and a haplotype-based genetic approach was used to elucidate the origin and distribution of resistance in both countries.RESULTS
Amaranthus palmeri populations were resistant to thifensulfuron-methyl and imazamox, and the 574-Leu mutant ALS allele was found to be the main cause of resistance among them. In two Spanish populations, 376-Glu and 197-Thr mutant ALS alleles were also found. The haplotype analyses revealed the presence of two and four distinct 574-Leu mutant haplotypes in the Italian and Spanish populations, respectively. None was common to both countries, but some mutant haplotypes were shared between geographically close populations or between populations more than 100 km apart. Wide genetic diversity was found in two very close Spanish populations.CONCLUSION
ALS-resistant A. palmeri populations were introduced to Italy and Spain from outside Europe. Populations from both countries have different evolutionary histories and originate from independent introduction events. ALS resistance then spread over short and long distances by seed dispersal. The higher number and genetic diversity among mutant haplotypes from the Spanish populations indicated recurrent invasions. The implementation of control tactics to limit seed dispersal and the establishment of A. palmeri is recommended in both countries. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. 相似文献5.
The ethanol and methanol extracts of Cassia auriculata flowers were screened for antioxidant activity. The antioxidant activity was determined by an improved assay based on the decolorization of the radical monocation of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging method. The ethanol and methanol extracts of C. auriculata flowers showed antioxidant activity in both assays. 相似文献
6.
Consuming Fuel and Fuelling Consumption: Modelling Human Caloric Demands and Fuelwood Use 总被引:1,自引:0,他引:1
This paper describes a conceptual framework that was developed to integrate livestock, human, cultivation and forest constraints
to model community fuelwood consumption over a 25-year planning horizon. This framework was constructed as an energy balance
based on human caloric requirements in order to examine the effects of household-level decisions for nutrition, fuelwood and
land use. A scenario from a virtual community in Uganda is presented to illustrate the utility of this model to allow rapid
policy and scenario evaluation. User-defined inputs combined with published research data are used in simulating resource
responses and energy consumption rates. This model is a potential tool to monitor fuelwood consumption and to understand the
implications of various land-use practices.
相似文献
Joel HartterEmail: |
7.
Researchers have found that changes in infiltration characteristics that result from surged flow, often inferred from advance trajectories, vary considerably with site and management practices. Previously developed methods for adjusting the infiltration function for the surged effect are examined to better understand these effects. The easily implemented cycle ratio-time (CRT) surged flow infiltration function indicates that soil and management factors can impact surged flow effectiveness. If changes in flow rate result in changes in the on/off pulse patterns, the CRT function will reflect this with changes in infiltration characteristics; otherwise the model is insensitive to changes in flow rate. The duration of the first surge has a more pronounced effect than later surges, and soils that reach steady state infiltration quickly are less likely to exhibit decreased infiltration rates as a result of surged flow. Surged flow simulation runs are used to show that the CRT function predicts differences in performance on opposite sides of tee-type surge valves; the result of uneven off-times associated with expanding cycle times. 相似文献
8.
Summary Central Asian apricot germplasm was used in hybridizations with California adapted apricots to increase Brix levels and improve fresh eating quality. Fruit from parental trees, the F1 hybrid and two backcross families were evaluated for fruit quality traits and analyzed by HPLC for specific sugar content. The F1 hybrid between Central Asian and California adapted apricots was intermediate to its parents in many of the evaluated characteristics and levels of specific sugars. When the F1 hybrid was backcrossed to California adapted apricots ‘Lorna’ and ‘Robada,’ the resulting hybrids were diverse in Brix, juice acidity, fruit size and profiles of specific sugars. Glucose: fructose ratios higher that 3.3 were encountered in fruit from five of the 22 analyzed seedlings, and fructose: sorbitol ratio ranged from 0.67 to 6.46. Brix and total sugar content correlated significantly with each other and with both sucrose and glucose. No significant correlations existed between sorbitol and any of the other analyzed sugars, nor with Brix or total sugars. The results demonstrated the extent of sugar profile modification possible in California adapted apricots after just two generations of breeding with Central Asian apricot germplasm. 相似文献
9.
Thomas B. Moorman Jennifer K. Cowan Ellen L. Arthur Joel R. Coats 《Biology and Fertility of Soils》2001,33(6):541-545
Pesticide contamination of soil and groundwater at agricultural chemical distribution sites is a widespread problem in the USA. Alternatives to land-farming or solid waste disposal include biostimulation and phytoremediation. This research investigated the ability of compost, corn stalks, corn fermentation byproduct, peat, manure, and sawdust at rates of 0.5% and 5% (w/w) to stimulate biodegradation of atrazine [6-chloro-N-ethyl-N'-(1-methyethyl)-1,3,5-triazine-2,4-diamine], metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide], and trifluralin [2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine] added as a mixture to soil. Initial concentrations were 175ᆾ mg atrazine kg-1 soil, 182ᆭ mg metolachlor kg-1 soil, and 165ᆫ mg trifluralin kg-1 soil. After amendment addition, 30% of the atrazine, 33% of the metolachlor, and 44% of the trifluralin was degraded over 245 days, which included 63 days' aging prior to amendment additions. Atrazine degradation was enhanced by 0.5% manure, 5% peat, and 5% cornstalk amendments compared to nonamended soils. Metolachlor degradation was enhanced by all amendments at the 5% level, except for compost and peat. Amendments had no effect on trifluralin degradation. The 5% addition of compost, manure, and cornstalks resulted in significant increases in bacterial populations and dehydrogenase activity. A second experiment compared the persistence of atrazine, metolachlor, and trifluralin applied in a mixture to their persistence in soil individually. A combined average of 123 mg atrazine kg-1 remained in soil treated with the three-herbicide mixture compared to 31 mg atrazine kg-1 remaining in soil treated with atrazine only. Atrazine mineralization and atrazine-degrading microorganisms were suppressed by high concentrations of metolachlor, but not by trifluralin. 相似文献
10.