全文获取类型
收费全文 | 56篇 |
免费 | 1篇 |
专业分类
林业 | 1篇 |
农学 | 3篇 |
2篇 | |
综合类 | 26篇 |
农作物 | 1篇 |
畜牧兽医 | 15篇 |
植物保护 | 9篇 |
出版年
2020年 | 1篇 |
2019年 | 1篇 |
2017年 | 1篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 1篇 |
2010年 | 1篇 |
2009年 | 2篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2006年 | 1篇 |
2002年 | 1篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1960年 | 1篇 |
1957年 | 5篇 |
1956年 | 4篇 |
1954年 | 4篇 |
1953年 | 1篇 |
1952年 | 1篇 |
1951年 | 1篇 |
1950年 | 1篇 |
1949年 | 1篇 |
1948年 | 1篇 |
1947年 | 1篇 |
1941年 | 2篇 |
1902年 | 1篇 |
排序方式: 共有57条查询结果,搜索用时 15 毫秒
41.
42.
Journal of Plant Diseases and Protection - In a survey of Botrytis populations in Northern Germany in 2012-2014, an average of 67.7% and 73.8% of isolates from strawberry and raspberry fields... 相似文献
43.
44.
Grasslands store large stocks of soil organic carbon(SOC) in the subsoil, but our knowledge of belowground processes becomes less robust with depth. Vertically explicit SOC models typically assume that the depth distribution of belowground production follows the depth distribution of belowground biomass, but this assumption has not been tested. In addition to the effects of soil temperature and moisture on decomposition, some vertically explicit SOC models implement an intrinsic decrease in belowground decomposition with depth, yet this effect has rarely been observed empirically. We simultaneously measured the depth distributions of belowground biomass, production, and litter decomposition to assess whether belowground biomass depth distributions were suitable predictors of belowground production and whether belowground decomposition decreased with soil profile depth. We found that live and total(live +dead) belowground biomass was distributed relatively more shallowly than total belowground production, and thus total belowground biomass was a biased predictor of the vertical distribution of belowground production. The depth distribution of live roots 2 mm in diameter was found to be the best predictor of total belowground production depth distribution. Using an intact decay core method,we found that belowground litter decomposition decreased by 49% from 0–10 to 30–40 cm depth, and model-simulated effects of soil temperature and moisture accounted for only 9% of the observed decrease with depth. Vertically explicit SOC models can be improved with more accurate empirical belowground production depth distribution estimates, but depth-specific decomposition rates currently implemented in SOC models are necessary to explain observed decreases in belowground litter decay with depth. 相似文献
45.
Effects of supplemental dietary vitamin C on quality of semen from Nile tilapia (Oreochromis niloticus) breeders
下载免费PDF全文
![点击此处可从《Reproduction in domestic animals》网站下载免费的PDF全文](/ch/ext_images/free.gif)
NLAF Sarmento EFF Martins DC Costa WS Silva CC Mattioli MR Luz RK Luz 《Reproduction in domestic animals》2017,52(1):144-152
The objective of this study was to evaluate the effects of vitamin C on growth and quality of semen from Oreochromis niloticus breeders. One hundred and sixty males were fed with different levels of vitamin C (0, 261, 599 and 942 mg/kg diet). The higher weight values were recorded for 599 (166 g) and 942 (175 g) mg of vitamin C/kg diet. Sperm motility, vigour and concentration were higher with 599 and 942 mg of vitamin C/kg diet. The semen volume, gonadosomatic index and plasma protein data from the last week showed a direct relationship with increasing levels of vitamin C. No changes were observed in the hepatosomatic index and blood glucose. The haematocrit and erythrocyte showed higher values estimated by equations derived at 850 and 638 mg vitamin C/kg diet, respectively. The leucocytes were inversely proportional to the increasing levels of vitamin C. After 100 days of feeding, animals fed the diet containing 942 mg vitamin C/kg diet had higher sperm motility, linearity, curvilinear velocity, straight line velocity and average path velocity (p < .05). Higher values of beat cross‐frequency were observed in broodfish fed diets containing 942 and 599 mg vitamin C/kg. The different vitamin C levels did not cause differences in straightness, lateral head displacement and sperm morphology. For Nile tilapia males on intensive rearing and handling conditions, vitamin C levels between 599 and 942 mg/kg may be used for a better performance and quality of semen. 相似文献
46.
J. A. von Arx 《European journal of plant pathology / European Foundation for Plant Pathology》1954,60(1):72-73
Zusammenfassung Infektionsversuche haben ergeben, dassPhomopsis dauci
von Arx scharf aufDaucus carota L. spezialisiert ist und andere Umbelliferen nicht antasten kann. Der Pilz kommt sowohl auf der Wildform wie auf den gezüchteten Rassen vonDaucus vor und geht leicht von der einen Form auf die andere über. 相似文献
47.
J. A. von Arx W. P. de Leeuw 《European journal of plant pathology / European Foundation for Plant Pathology》1954,60(6):251-252
Zusammenfassung Auf der mehrjärigen ZierpflanzeAchillea ptarmica L. var.multiplex
Heim Perry's White wurde in einigen Gärtnereien eine durch den AscomycetenSchizothyrioma ptarmicae (DC.) v.Höhn. verursachte Krankheit beobachtet. Der Pilz befällt die Stengel (Fig. 1), Blätter und Blüten (Fig. 2), wo zwischen Kutikula und Epidermis die bereits auf der lebenden Pflanze reifenden Ascusfrüchte (Fig. 3) angelegt werden. Die befallenen Pflanzen sterben nicht ab, bleiben aber in ihrem Wachstum zurück und werden unansehnlich. Verschleppung erfolgt wahrscheinlich durch Saatbefall. Der Pilz war bisher nur auf der wild wachsenden Form vonAchillea ptarmica bekannt.
Mit Zusammenfassung: Eine Pilzkrankheit auf Achillea ptarmica L相似文献
48.
49.
The combined effect of fertilizing with different forms of organic fertilizer
The' IOSDV field experiment, testing mineral-nitrogen fertilizer in combination with different forms of organic manure over a period of 6 years (two crop-rotation cycles) has provided specific results concerning the interaction of the components of fertilizers. Stable manure had an intensive effect on sugar beet but only a weak effect on winter wheat. Sugar-beet leaves had a strong effect on winter wheat but little effect on winter barley. Straw -green manure showed a growing effect on winter barley. As expected, the effect of fertilizing is influenced by climatic factors. Yield curves with the specific parameters 'M', 'm' and 'i' show – as would be expected – that the effect of the organic manure on yield is chiefly expressed at lower levels of mineral-nitrogen manure. In this way, the curves indicate the optimal level of N-fertilization. The balance of nutrients show that organic variances have different effects on the N-balance. The interval evaluation shows the importance of long-term experiments. 相似文献
The' IOSDV field experiment, testing mineral-nitrogen fertilizer in combination with different forms of organic manure over a period of 6 years (two crop-rotation cycles) has provided specific results concerning the interaction of the components of fertilizers. Stable manure had an intensive effect on sugar beet but only a weak effect on winter wheat. Sugar-beet leaves had a strong effect on winter wheat but little effect on winter barley. Straw -green manure showed a growing effect on winter barley. As expected, the effect of fertilizing is influenced by climatic factors. Yield curves with the specific parameters 'M', 'm' and 'i' show – as would be expected – that the effect of the organic manure on yield is chiefly expressed at lower levels of mineral-nitrogen manure. In this way, the curves indicate the optimal level of N-fertilization. The balance of nutrients show that organic variances have different effects on the N-balance. The interval evaluation shows the importance of long-term experiments. 相似文献
50.
The function of leptin in livestock species has been intensively studied during recent years. Due to the associations between plasma leptin concentrations and body fat, leptin could be used as an indicator for the in vivo evaluation of carcass composition in breeding programs. This review specifically discusses leptin mRNA expression in several fat tissues, the relationship between plasma leptin and body fat and the influence of fasting on this association. It also refers to the limitations of the use of plasma leptin concentrations as a predictor for selection purposes in breeding animals. Furthermore, single nucleotide polymorphisms in the leptin gene have some effects on carcass traits and the leptin gene is considered to be a candidate gene for a marker‐assisted selection. However, these results are very inconsistent across various populations and need to be confirmed in future studies before leptin can be used efficiently in breeding programs and management. 相似文献