全文获取类型
收费全文 | 244篇 |
免费 | 5篇 |
专业分类
林业 | 23篇 |
农学 | 4篇 |
基础科学 | 1篇 |
87篇 | |
综合类 | 9篇 |
农作物 | 17篇 |
水产渔业 | 13篇 |
畜牧兽医 | 77篇 |
园艺 | 10篇 |
植物保护 | 8篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 14篇 |
2017年 | 8篇 |
2016年 | 9篇 |
2015年 | 6篇 |
2014年 | 13篇 |
2013年 | 12篇 |
2012年 | 15篇 |
2011年 | 30篇 |
2010年 | 23篇 |
2009年 | 15篇 |
2008年 | 13篇 |
2007年 | 20篇 |
2006年 | 7篇 |
2005年 | 11篇 |
2004年 | 12篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有249条查询结果,搜索用时 15 毫秒
31.
José Zilton Lopes Santos Bruno Fernando Faria Pereira José Augusto Figueira da Silva Carlos Alberto Franco Tucci Sílvio Vieira da Silva Tainah Manuela Benlolo Barbosa 《Communications in Soil Science and Plant Analysis》2017,48(11):1280-1290
We evaluated the effects of macronutrient and micronutrient omission, and of liming, on Jatropha curcas (JC) in greenhouse study. The experimental design was a factorial combination of 2 liming treatments (nil or 4.5 t. ha?1 of dolomitic lime) x 7 combinations of fertility status, with five replications. The concentrations and uptake of nutrients by JC plants follow the order: nitrogen > potassium > calcium ≥ Magnesium > sulfur > phosphorus > iron > boron > manganese > zinc > copper (N > K > Ca ≥ Mg > S > P > Fe > B > Mn > Zn > Cu), but the growth of JC plants was negatively affected mainly by omission of macronutrients, in the following order: P > N = K = S, on limed soil. Phosphorus is the most critical element for development. JC is responsive to micronutrients only when applied together with macronutrients. Potassium chloride is not recommended as K+ source for JC crop. Lime is recommended to improve growth and nutritional status of JC plants. 相似文献
32.
Jo?o C. Fernandes Humberto Spindola Vanessa de Sousa Alice Santos-Silva Manuela E. Pintado Francisco Xavier Malcata Jo?o E. Carvalho 《Marine drugs》2010,8(6):1763-1768
All the reports to date on the anti-inflammatory activity of chitooligosaccharides (COS) are mostly based on in vitro methods. In this work, the anti-inflammatory activity of two COS mixtures is characterized in vivo (using balb/c mice), following the carrageenan-induced paw edema method. This is a widely accepted animal model of acute inflammation to evaluate the anti-inflammatory effect of drugs. Our data suggest that COS possess anti-inflammatory activity, which is dependent on dose and, at higher doses, also on the molecular weight. A single dose of 500 mg/kg b.w. weight may be suitable to treat acute inflammation cases; however, further studies are needed to ascertain the effect upon longer inflammation periods as well as studies upon the bioavailability of these compounds. 相似文献
33.
Cassia et al. (2006) claim that each industry develops along a specific industry life cycle with four stages: introduction, growth, maturity and decline. This essay tries to analyze the German fruit-growing industry by the means of the industry life cycle model. The main aspects of the analysis are “consumption and prices”, “competition”, “product innovation” and “process innovation”. In summary, the German professional fruit-growing industry might be classified as to be in the mature stage. 相似文献
34.
Snow avalanches are common in mountain environments, sometimes affecting inhabited areas and infrastructures (e.g. roads, bridges, and ski slopes). Their study is widespread and involves the use of a variety of different techniques, including dendrochronological methods. The aim of such investigations is principally to date past events, but also to detect variation in avalanche frequency as well as their spatial distribution. Trees affected by snow avalanches generally have scars, tilted trunks and broken branches, which allow past events to be dated to within a year. In this work tree rings were used to investigate a disruptive snow avalanche which occurred in 2001 in Val Mala in the Italian Alps. The event almost completely removed forest along the flow path, while the snow powder component of the avalanche also impacted on the adjacent forest. Comparison of tree reaction in surviving plants along the flow path and vegetation on the border showed i) the production of reaction wood even in apparently undisturbed trees and ii) the usefulness of border plants for dating past events. Different dendroecological indicators were investigated (i.e. reaction wood, scars, traumatic resin ducts, and variations in stem eccentricity) and reaction wood is evidently concentrated from 2001 not only in damaged trees but also in adjacent plants. The potential to investigate past snow avalanches by collecting samples from trees growing in border areas is presented: in the specific case of Val Mala, vegetation bordering the flow paths reacted to produce reaction wood in 2001, in a similar manner to plants along the flow track, demonstrating their usefulness in such investigations. Their response to the 2001 event confirms the possibility of applying dendrochronological techniques to trees adjacent to the flow path, even if they appear morphologically undisturbed, and proposes to use only border areas in cases of an absence of sufficient trees along the avalanche track. 相似文献
35.
Nagy A Ziadinov I Schweiger A Schnyder M Deplazes P 《Berliner und Münchener tier?rztliche Wochenschrift》2011,124(11-12):503-511
Infections of dogs with Toxocara canis and Echinococcus multilocularis pose an infection-risk particularly for contact persons. We examined specimens of hair coat and faeces of 124 farm dogs, 118 household dogs, 49 kennel dogs, 15 puppies from two litters, and 46 red foxes. Microscopically identified eggs of Toxocara or taeniids were further investigated by species-specific PCRs. In farm dogs, eggs of E. multilocularis or T. canis were identified in each 2.4% of faecal samples, eggs of T. cati (gastrointestinal passage) in 7.3%, respectively. Household dogs excreted eggs of T. canis (0.8%) and of T. cati (2.5%). In kennel dogs, eggs of T. canis (4.1%), but not of T. cati were detectable. Coat samples contaminated with eggs of Toxocara spp. were found from farm dogs (5.6%), household dogs (1.7%) and kennel dogs (2.0%). Taeniid eggs were isolated from the coat samples from only two farm dogs (1.6%); a molecular species determination was not achieved. In six intrauterinely infected puppies, Toxocara-eggs were found in 17/38 samples taken within six weeks. No intact Toxocara eggs could be isolated from the coat of nine puppies from a second litter 13 days after deworming. Of the 46 red foxes investigated (dissection and faecal samples) 13 (28.3%) were infected with E. multilocularis and 20 (43.5%) with Toxocara. Eggs of taeniids and Toxocara were found in 13% (in three cases confirmed as E. multilocularis) and 21.7%, respectively, of the coat samples. None of the retrieved Toxocara eggs in the coat samples were embryonated. Thus, an infection of humans through the transmission of E. multilocularis eggs after direct contact with dogs or foxes is conceivable, whereas a corresponding infection risk by Toxocara eggs must be critically challenged. 相似文献
36.
Duvaucel geckos (Hoplodactylus duvaucelii) are large endemic lizards that have been extirpated from the New Zealand mainland due to introduced mammalian predators. This species has subsequently become the subject of species translocation conservation management in an endeavour to increase the number of populations and as a part of island ecological restoration. Blood sampling of a captive adult male after tail autotomy led to the discovery of a Rickettsia-like organism within this gecko's erythrocytes. We conclude that this infection was acquired at the gecko's source location, a remote island closed to the general public and lacking potential invasive parasite reservoir reptiles. The likely vector is the native mite Geckobia naultina. This finding represents valuable new baseline information about the health parameters of this threatened species. Particularly in the light of the paucity of reported blood parasitism in New Zealand reptiles, the conservation management of this species through relocation and captive-breeding, and the on-going concerns regarding the introduction of novel parasites to New Zealand. 相似文献
37.
Simonetta Bullitta Sandro Dettori Manuela Manchinu Maria Rosaria Filigheddu Giovanna Piluzza 《Genetic Resources and Crop Evolution》2011,58(7):1007-1020
Considering the very high socio economic value of cork oak (Quercus suber L.) in Mediterranean areas, a better knowledge of local genetic resources is necessary in order to reach a good balance between
the conservation issues and the need of an efficient cork production network. In such frame, local germplasm of Q. suber from the main cork production areas of Sardinia was analysed for DNA and isozyme polymorphisms and for cork quality in relation
to some environmental parameters. A total number of 24 sample stands of cork oak were selected, representing typical vegetation,
sylvicultural and cork quality features within the eight identified cork growing areas in Sardinia. Considerable variation
was found between cork oak stands of the different areas. Results of the principal component analysis performed on the cork
quality data and environmental characters of the eight areas, showed that the first three components explain 72.2% of the
variation. The major characters involved in this differentiation were cork quality characters such as dimensional recover,
moisture and Mg content of the cork and also elevation of stands m a.s.l. for the first component. The second component appears
to be determined by some climatic parameters (average annual temperature and average of the minimum temperatures of coldest
month) and by the Fe and Zn in the cork. For the third component, major characters involved in differentiation are average
annual rainfall, bark thickness and Ca content in the cork. 相似文献
38.
Summary Thermotherapy of PVX infected potato plants at 30°C followed by in vitro tip culture at 24°C was more or less successful depending
on the duration of the heart treatment. Virus inactivation in meristematic tissues was much more efficient when the heat treatment
was applied to mature plants rather than to meristem tips cultured in viro. By combining 30°C treatment of potato plants with
30°C tip culture. PVX eradication was not improved but the final proportion of PVX-free plantlets was increased because the
tip population developed faster, giving a higher number of rooted plantlets at 30°C than at 24°C. 相似文献
39.
Chemical composition and antimicrobial activity of Momordica charantia seed essential oil 总被引:1,自引:0,他引:1
The essential oil obtained from the seeds of Momordica charantia was analyzed by GC/MS. Twenty-five components, representing 90.9% of the oil, were identified. The main constituents were trans-nerolidol, apiole, cis-dihydrocarveol and germacrene D. Furthermore, the oil was tested for its antibacterial and antifungal activities. Staphylococcus aureus was found to be the most sensitive microorganism with MIC values <500 microg/ml. 相似文献
40.
Manuela S. Kaufmann Christian von Hebel Lutz Weihermüller Michael Baumecker Thomas Döring Kathlin Schweitzer Eleanor Hobley Sara L. Bauke Wulf Amelung Harry Vereecken Jan van der Kruk 《Soil Use and Management》2020,36(1):104-116
Electromagnetic induction (EMI) data are often used to investigate spatial and temporal patterns of soil texture, soil water content and soil salinity. We hypothesized that the EMI methodology might thus also offer potential to detect agricultural legacy effects originating from fertilizer application and irrigation of different fields. Therefore, we performed EMI measurements on two long-term field experiments (LTFE) at Thyrow near Berlin (Germany) that differed in agricultural management with regard to long-term irrigation in combination with mineral (NPK and lime) and organic amendments (straw and farmyard manure). Two different rigid-boom multi-coil EMI instruments were used to measure simultaneously the apparent electrical conductivity (ECa) over nine different depth ranges to study the entire soil profile from topsoil to deep subsoil. Additionally, soil samples were taken from the different treatments to ground-truth the measurements and disentangle the nutrient application or irrigation effects from natural soil heterogeneity. The soil samples indicated a rather homogenous soil and the correlation between soil parameters or states were not significant. However, the treatments showed significant differences in measured ECa values. In general, ECa values were largest on regularly irrigated as well as on mineral and organic fertilized plots, with regular irrigation exhibiting the largest impact on EMI records even though the last application was months before the EMI measurement. Overall, this study reveals that EMI data can support the classical in situ assessment of agricultural management effects within LTFE, while offering new potentials in detecting and understanding legacy effects of agricultural management on spatial soil properties at farm level. 相似文献