全文获取类型
收费全文 | 183篇 |
免费 | 8篇 |
专业分类
林业 | 19篇 |
农学 | 3篇 |
38篇 | |
综合类 | 54篇 |
农作物 | 7篇 |
水产渔业 | 2篇 |
畜牧兽医 | 40篇 |
园艺 | 12篇 |
植物保护 | 16篇 |
出版年
2020年 | 2篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 8篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 5篇 |
2012年 | 12篇 |
2011年 | 18篇 |
2010年 | 5篇 |
2009年 | 6篇 |
2008年 | 7篇 |
2007年 | 7篇 |
2006年 | 9篇 |
2005年 | 2篇 |
2004年 | 8篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 2篇 |
1998年 | 2篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1974年 | 3篇 |
1971年 | 2篇 |
1926年 | 1篇 |
1924年 | 1篇 |
1920年 | 2篇 |
1917年 | 2篇 |
1916年 | 1篇 |
1915年 | 1篇 |
1913年 | 3篇 |
1912年 | 1篇 |
1911年 | 1篇 |
1909年 | 1篇 |
1903年 | 2篇 |
1894年 | 1篇 |
1891年 | 1篇 |
1890年 | 1篇 |
1888年 | 3篇 |
1887年 | 4篇 |
1886年 | 1篇 |
1885年 | 1篇 |
1884年 | 2篇 |
排序方式: 共有191条查询结果,搜索用时 15 毫秒
1.
Yeasts are potential antagonists of microorganisms in the phyllosphere. Due to their osmotolerance, they should also be able to colonize apple flowers. In field experiments, we applied yeast agents against fireblight at two different sites in the southern part of Germany. They showed efficiencies 0–20% below Plantomycin (streptomycin). Co-culture experiments in liquid basal media with synthetic nectar resulted in suppression of Erwinia amylovora by yeast. This effect could not be confirmed with population studies of yeasts and E. amylovora in flower clusters. Field and laboratory experiments indicated that yeasts have antagonistic properties against fireblight but further research is needed to investigate this potential. 相似文献
2.
Induced Disease Resistance in Plants by Chemicals 总被引:23,自引:0,他引:23
Michael Oostendorp Walter Kunz Bob Dietrich Theodor Staub 《European journal of plant pathology / European Foundation for Plant Pathology》2001,107(1):19-28
Plants can be induced locally and systemically to become more resistant to diseases through various biotic or abiotic stresses. The biological inducers include necrotizing pathogens, non- pathogens or root colonizing bacteria. Through at network of signal pathways they induce resistance spectra and marker proteins that are characteristic for the different plant species and activation systems. The best characterized signal pathway for systemically induced resistance is SAR (systemic acquired resistance) that is activated by localized infections with necrotizing pathogens. It is characterized by protection against a broad range of pathogens, by a set of induced proteins and by its dependence on salicylic acid (SA) Various chemicals have been discovered that seem to act at various points in these defense activating networks and mimic all or parts of the biological activation of resistance. Of these, only few have reached commercialization. The best- studied resistance activator is acibenzolar-5-methyl (BION). At low rates it activates resistance in many crops against a broad spectrum of diseases, including fungi, bacteria and viruses. In monocots, activated resistance by BION typically is very long lasting, while the lasting effect is less pronounced in dicots. BION is translocated systemically in plants and can take the place of SA in the natural SAR signal pathway, inducing the same spectrum of resistance and the same set of molecular markers. Probenazole (ORYZEMATE) is used mainly on rice against rice blast and bacterial leaf blight. Its mode of action is not well understood partly because biological systems of systemically induced resistance are not well defined in rice. Treated plants clearly respond faster and in a resistant manner to infections by the two pathogens. Other compounds like beta-aminobutyric acid as wdl as extracts from plants and microorganisms have also been described as resistance inducers. For most of these, neither the mode of action nor reliable pre-challenge markers are known and still other pathways for resistance activation are suspected. Resistance inducing chemicals that are able to induce broad disease resistance offer an additional option for the farmer to complement genetic disease resistance and the use of fungicides. If integrated properly in plant health management programs, they can prolong the useful life of both the resistance genes and the fungicides presently used. 相似文献
3.
Trypanosoma cruzi-like flagellates were incidentally noted in blood smears of a routinely monitored rhesus monkey experimentally infected with the simian immunodeficiency virus (SIV). Immunodeficiency in the course of the SIV infection reactivated a chronic infection of Chagas' disease that had been unnoticed when the macaque was imported to Europe. The animal developed no specific clinical symptoms of American trypanosomiasis, but histologically a chagasic myocarditis was detected. Analysis of the small subunit rRNA gene of the trypanosome identified the protozoan as T. cruzi. 相似文献
4.
Serean L Adams John F Smith Rodney D Roberts Achim R Janke Nick G King Harry Robin Tervit Stephen C Webb 《Aquaculture Research》2008,39(13):1434-1442
The robustness of Pacific oyster, Crassostrea gigas (Thunberg), sperm cryopreservation in the context of selective breeding based on family lines was investigated. Irrespective of egg density, high fertilization success was achieved with cryopreserved sperm when sperm:egg ratios of 1000:1 to 10 000:1 were used. Variation among replicate runs on the same oyster batches was minimal, indicating that cryopreservation and larval rearing procedures were repeatable. Twenty independent single male–female crosses were made to assess the utility of cryopreserved sperm in selective breeding. The fertility of unfrozen sperm was generally a poor predictor of cryopreserved sperm fertility. Based on D‐larval yields, 17 of the 20 crosses were likely to yield adequate spat for selective breeding (>105 D‐larvae from 1 million eggs), two were marginal (5 × 104 D‐larvae) and one was inadequate (4 × 103 D‐larvae). An alternative fertilization strategy to improve D‐yield from a given number of sperm was then tested. Fertilizing 10 million eggs at a sperm:egg ratio of 200:1 increased the total D‐yield when compared with fertilizing 1 million eggs at a sperm:egg ratio of 2000:1 for the same male–female pair. We conclude that, despite wide variation in fertility, cryopreserved sperm is useful for family production. 相似文献
5.
6.
7.
Blowflies (Calliphoridae) and vacuum-packed ham
In a few cases blowfly maggots have been reported from vacuum-packed ham. The possibility of egg-hatching and larval development in the product was analysed. In experiments no hatching of blowfly eggs on vacuum-packed, boiled, sliced ham occurred. However, the eggs are not killed immediately; 1–4 days after the packing, they are still viable and when the wrapping is broken, hatching may occur. After a stay of 7–10 days on vacuum-packed ham, the viability of the eggs seems lost. In the actual case the risk of oviposition by blowflies on ham in the cannery and succeeding larval development in the product is considered to be very low. 相似文献
8.
Briviba K Stracke BA Rüfer CE Watzl B Weibel FP Bub A 《Journal of agricultural and food chemistry》2007,55(19):7716-7721
The present study was performed to compare the effects on antioxidant activity and on DNA damage of organic and conventionally produced apples grown under controlled conditions in human peripheral blood lymphocytes. Six healthy volunteers consumed either organically or conventionally grown apples (Golden Delicious, 1000 g) from two neighboring commercial farms in a double-blinded, randomized, cross-over study. The average content of total identified and quantified polyphenols in the organically and conventionally produced apples was 308 and 321 microg/g fresh weight, respectively. No statistically significant differences in the sum of phenolic compounds or in either of the polyphenol classes were found between the agricultural methods. Consumption of neither organically nor conventionally grown apples caused any changes in antioxidant capacity of low-density lipoproteins (lag time test), endogenous DNA strand breaks, Fpg protein-sensitive sites, or capacity to protect DNA against damage caused by hydrogen peroxide. However, a statistically significant decrease in the levels of endonuclease III sensitive sites and an increased capacity to protect DNA against damage induced by iron chloride were determined 24 h after consumption in both groups of either organic or conventionally grown apples, indicating the similar antigenotoxic potential of both organically and conventionally grown apples. 相似文献
9.
Bulk stomatal resistance of Vicia faba and its dependence on soil water content Bulk stomatal resistance of beans (Vicia faba L.,) as a function of soil water content was estimated for 41 days by comparison of potential transpiration, determined from meteorological data, and actual transpiration, determined from soil water losses. The resistance of beans is about 46 s/m if soil water content is above 70 % of available field capacity and increases strongly in dryer situations. This behaviour can be described by an exponential function. 相似文献
10.
Achim Ellies 《植物养料与土壤学杂志》1987,150(5):327-333
Mechanical soil properties as criteria for the classification of Andepts The shear strenght in the upper layer of seven different Andepts from southern Chile was examined. The samples were taken from sites of a middle slope position, in one of the Andepts from five positions of catena. The intention was to determine the variation of shear strenght properties, within and between the soil series. Moreover, some physical and chemical properties of the soils were determined. The evaluation includes multiple regressions, principal component analyses (PCA) and cluster analyses, in order to check the interrelation of soil properties for grouping the samples. The variables of the first two components between the series which show the greatest variability of the soil properties are consistency characteristics and shear strenght parameters. The PCA permit conclusion that the shear strenght parameters are useful criteria for grouping the analysed Andepts. However, they contribute only moderately to the total variation between the samples of the studied catena. The groups of soil samples formed by the series from the same topographic position are closely related to their distance from the Andes and their particle size distribution. The groups formed by the samples from the catena, show the humidity of the site as a common influence factor. 相似文献