全文获取类型
收费全文 | 77篇 |
免费 | 0篇 |
专业分类
林业 | 11篇 |
农学 | 1篇 |
15篇 | |
综合类 | 4篇 |
农作物 | 2篇 |
水产渔业 | 4篇 |
畜牧兽医 | 35篇 |
园艺 | 2篇 |
植物保护 | 3篇 |
出版年
2021年 | 3篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 4篇 |
2012年 | 7篇 |
2011年 | 6篇 |
2010年 | 1篇 |
2009年 | 1篇 |
2008年 | 2篇 |
2007年 | 2篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 6篇 |
2003年 | 8篇 |
2002年 | 4篇 |
1995年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1931年 | 1篇 |
排序方式: 共有77条查询结果,搜索用时 16 毫秒
51.
Several studies have been conducted in the past on carbon stock measurements in the tropical forests of Indonesia.This study is the first related research conducted in the New Guinea Island.In a degraded logged-over secondary forest in Manokwari Regency (West Papua,Indonesia),carbon stocks were measured for seven parts,i.e.,above-ground biomass (AGB),below-ground biomass (BGB),under-storey biomass (B u),necromass of dead leaves (N l),necromass of dead trees (N t),litter (L) and soil (S) using appropriate equations and laboratory analysis.Total carbon stocks were measured at 642.8 tC·ha-1 in the low disturbance area,536.9 tC·ha-1 in the moderate disturbance area and 490.4 tC·ha-1 in the high disturbance area.B u,N l and N t were not significant in the carbon stock and were collectively categorized as a total biomass complex.The carbon stock of litter was nearly equal to that of the total biomass complex,while the total carbon stock in the soil was eight times larger than the total biomass complex or the carbon stock of the litter.We confirmed that the average ratio of AGB and BGB to the total biomass (TB) was about 84.7% and 15.3%,respectively.Improvements were made to the equations in the low disturbance logged-over secondary forest area,applying corrections to the amounts of biomass of sample trees,based on representative commercial trees of category one.TB stocks before and after correction were estimated to be 84.4 and 106.7 tC·ha-1,indicating that these corrections added significant amounts of tree biomass (26.4%) during the sampling procedure.In conclusion,the equations for tree biomass developed in this study,will be useful for evaluating total carbon stocks,especially TB stocks in logged-over secondary forests throughout the Papua region. 相似文献
52.
53.
Arno Wünschmann Robert Lopez-Astacio Aníbal G. Armin Leslie Reed Colin R. Parrish 《Journal of veterinary diagnostic investigation》2021,33(1):140
A juvenile raccoon was euthanized because of severe neurologic signs. At postmortem examination, no significant gross lesions were present. Histologic evaluation demonstrated nonsuppurative encephalitis in thalamus, brainstem, and hippocampus, cerebellar Purkinje cell loss, as well as poliomyelitis and demyelination of the spinal cord. Parvovirus antigen–specific immunohistochemistry revealed immunopositive neurons in the brainstem, cerebral cortex, and hippocampus. A few Purkinje cells were also immunopositive. DNA extracted from formalin-fixed, paraffin-embedded brain tissue (thalamus, hippocampus, cerebral cortex) yielded a positive signal using PCR targeting both feline and canine parvovirus. Sequencing analyses from a fragment of the NS1 gene and a portion of the VP2 gene confirmed the presence of DNA of a recent canine parvovirus variant (CPV-2a–like virus) in the cerebellum. Our case provides evidence that a recent canine parvovirus (CPV) strain (Carnivore protoparvovirus 1) can infect cerebral and diencephalic neurons and cause encephalitis in an otherwise healthy raccoon. Parvovirus-induced encephalitis is a differential diagnosis of rabies and canine distemper in raccoons with neurologic signs. 相似文献
54.
Mauricio Montaño Lucien Hoffmann Albertinka Jacoba Murk Arno Christian Gutleb 《Journal of Soils and Sediments》2014,14(6):1200-1212
Purpose
Bioassays have become an alternative for sediment risk profiling, including potential compliance with sediment quality criteria (SQC). In vitro functional bioassays have evolved through standardization and validation towards a confident toxicological hazard estimate of sediments. Sample preparation is a key aspect for the improvement of bioassays. It is a standard practice to use a high single-stock concentration of extracts to further dilute test concentrations from and carry out the analysis. This study was carried out to demonstrate that high a contaminant load in a sediment extract (>20 g sediment equivalents (SEQ) ml?1) oversaturates solubility in carrier solvents and overloads the clean-up columns, potentially resulting in an under- or overestimation of the quantified dioxin-like toxic potency.Materials and methods
Cleaned nonpolar sediment extracts were prepared from samples collected from various locations in Luxembourg. The influence on the quantified toxic potency of the initial stock concentration, sonication assisted dissolution and exposure period in an in vitro bioassay for dioxin-like toxic potency (Bio-TEQ) was evaluated, as well as its impact on the sediment risk characterization according to SQC.Results and discussion
Stock sonication before serial dilution strongly reduced the standard variation of the outcomes. Higher initial stock concentrations (>20 g SEQ ml?1 for contaminated sediments) produced significantly lower Bio-TEQs g SEQ?1 compared to those obtained with initial stock concentrations of 2 g SEQ ml?1, probably due to solvent oversaturation. An initial stock concentration of 2 g SEQ ml?1 is low enough to prevent mis-estimation, but 20 or even 200 g SEQ ml?1 might be used when quantification of Bio-TEQ is required. The overload of extract on clean-up columns caused an overestimation of the dioxin-like potency probably due to PAH-induced false-positive responses.Conclusions
Higher contaminant load in the initial extracts from sediments affects the reliability of in vitro Bio-TEQ sediment quantification. Advice is given on how to avoid underestimation because of extract oversaturation, avoid overestimation because of overload of clean-up columns and reduce variability by applying sonication in standard testing protocols for risk characterization and quantification of the sample’s toxic potency. Taking into account the new aspects revealed in this study, in addition to important issues for quality control that are already included, the in vitro bioassays based on Bio-TEQs can be applied in a comprehensive monitoring program to determine whether sediments comply with health and safety standards for humans and the environment. 相似文献55.
By addition of phenol at concentrations between 0.1 and 10 mmol·l?1, nitrogenase activity (acetylene reduction assay) is enhanced by a factor of 5 in the rhizosphere of Pennisetum glaucum (pearl millet) incubated under 20% O2. No increase is found under microaerobic conditions. This enhancement effect is also noticed in a soil amended with a sucrose concentration of 20 mmol·l?1. Under those conditions, however, an enhancement is found under aerobic as well as under microaerobic conditions and a further increase of the phenol added reduces the activity to almost zero. A 4-fold increase of N2-fixation by phenol addition under aerobic conditions was determined with homogenous sediments from a fresh water lake while anaerobic N2-fixation was already slightly reduced by the same concentration added. Excised roots of Sorghum nutans CSH 5 failed to show any phenol enhancement of nitrogenase activity. After a preincubation of 6h, inhibition of nitrogenase activity under air by addition of 1 mmol·l?1 was much more pronounced than under microaerobic conditions. 相似文献
56.
Arno Semmel 《CATENA》1977,3(3-4)
Lithological factors are decisive for the development of soils and relief of the Harer Plateau, which belongs climatologically to the seasonally humid tropics On the crystalline basement planation surfaces with deeply weathered red latosols are dominant. Rising above these planation surfaces are limestone escarpments with vertisols of shallow to medium depth. The presence of sheet wash sediments on the plains, which can reach a considerable thickness in some parts, is interpreted as the result of Holocene climatic changes
Zusammenfassung
Für die Boden- und Reliefentwicklung im Harer-Plateau, das klimatisch den wechselfeuchten Tropen zuzurechnen ist, sind die Gesteinsverhältnisse ausschlaggebend. Im Kristallin herrschen flächenhafte Formen mit tiefgründigen Rotlehmen vor, über die Schichtstufen aus Kalkstein aufragen, der flach- bis mittelgründige Vertisole trägt. Das Vorkommen von teilweise recht mächtigen Abspülsedimenten in den Ebenen wird als Ergebnis von Klimaänderungen im Holozän gedeutet. 相似文献57.
Arno Wünschmann Rodney Frank Kem Pomeroy Sanjay Kapil 《Journal of veterinary diagnostic investigation》2002,14(5):441-444
A case of an enteric coronavirus infection in a 6-week-old dromedary calf is described. The animal had diarrhea for 5 days and died despite symptomatic treatment. Numerous viral particles, approximately 140 nm in diameter, with club-like projections were detected in the feces by electron microscopy. These characteristics were consistent with a coronavirus. Immunohistochemical reactivity with 2 antigenic group II coronavirus-specific antibodies confirmed the presence of viral antigen in colonic epithelial cells. The death of the animal was attributed to a neutrophilic and emphysematous colitis that likely was caused by an infection with a Clostridium sp. 相似文献
58.
59.
Arno ErasmusCheryl L. Lennox Hennie JordaanJoseph L. Smilanick Keith LesarPaul H. Fourie 《Postharvest Biology and Technology》2011,62(2):193-203
Imazalil (IMZ) is commonly applied in South African citrus packhouses for the control of green mould, caused by Penicillium digitatum, yet the disease still causes significant postharvest losses. The maximum residue limit (MRL) for IMZ on citrus fruit is 5 μg g−1, whereas 2-3 μg g−1 is a biologically effective residue level that should at least inhibit green mould sporulation. Standard compliance auditing of residue levels of citrus fruit, however, indicate that fruit from the majority of packhouses have residues of ≈1 μg g−1. Poor disease control from insufficient residue loading might further be compounded by the presence of IMZ-resistant isolates of P. digitatum in packhouses. This study was conducted to assess the current status of IMZ application in South African packhouses, to determine the adequate residue levels needed to control green mould and inhibit its sporulation using both IMZ sensitive and resistant isolates, to investigate IMZ application methods and resultant residue levels in commercial citrus packhouses, and to study optimisation of modes of IMZ application in citrus packhouses. Factors studied were IMZ concentration, application type (spray vs. dip and drench), exposure time, solution temperature and pH, as well as curative and protective control of P. digitatum. The packhouse survey showed that the majority of packhouses applied IMZ in a sulphate salt formulation through a fungicide dip tank, and loaded an IMZ residue of ≈1 μg g−1. In dip applications, IMZ had excellent curative and protective activity against Penicillium isolates sensitive to IMZ. However, curative control of IMZ resistant isolates was substantially reduced and protective control was lost, even at twice the recommended concentration, nor was sporulation inhibited. The use of sodium bicarbonate (2%) buffered imazalil sulphate solutions at pH ±8, compared with pH ±3 of the unbuffered solutions, markedly increased IMZ residue loading on Navel and Valencia oranges and improved curative and protective control of IMZ resistant isolates. Exposure time did not affect IMZ residue loading in IMZ sulphate solutions at pH 3, although the MRL was exceeded after 45 s exposure in pH 8 solutions. Imazalil applied through spray or drench application improved residue loading, but green mould control was less effective than after dip application. 相似文献
60.
Wolf TM Wünschmann A Morningstar-Shaw B Pantlin GC Rasmussen JM Thompson RL 《Journal of zoo and wildlife medicine》2011,42(4):694-699
An outbreak of Salmonella enterica serotype Choleraesuis enteritis occurred in two juvenile goitered gazelles and an adult Malayan tapir over a period of 5 wk at the Minnesota Zoo. Diagnosis was made postmortem on one gazelle and one tapir, and a second gazelle was diagnosed via fecal culture. The death of the tapir was attributed to S. enterica serovar Choleraesuis septicemia, while salmonellosis was considered to be a contributing factor besides ostertagiasis for the death of one goitered gazelle and for the diarrhea of another goitered gazelle. A third gazelle became ill in the same time period, but Salmonella infection was not confirmed by culture. All exhibited the clinical signs of profuse, watery diarrhea. The gazelles developed a protein-losing enteropathy, and the tapir showed signs of sepsis and endotoxemia. Serotyping and pulsed-field gel electrophoresis revealed the Salmonella isolates to be indistinguishable from each other. One year prior to this outbreak, Salmonella sp. was cultured from a Visayan warty pig (Sus cebifrons) housed in the same building as the tapir. After further investigation into the outbreak, spread of this pathogen was speculated to be associated with human movement across animal areas. 相似文献