全文获取类型
收费全文 | 199篇 |
免费 | 5篇 |
专业分类
林业 | 13篇 |
农学 | 24篇 |
58篇 | |
综合类 | 27篇 |
农作物 | 8篇 |
水产渔业 | 14篇 |
畜牧兽医 | 49篇 |
园艺 | 1篇 |
植物保护 | 10篇 |
出版年
2022年 | 2篇 |
2019年 | 6篇 |
2018年 | 1篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 6篇 |
2013年 | 13篇 |
2012年 | 10篇 |
2011年 | 11篇 |
2010年 | 8篇 |
2009年 | 7篇 |
2008年 | 11篇 |
2007年 | 13篇 |
2006年 | 14篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 2篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1963年 | 1篇 |
1941年 | 2篇 |
1940年 | 1篇 |
1903年 | 1篇 |
1865年 | 1篇 |
排序方式: 共有204条查询结果,搜索用时 0 毫秒
41.
Katarzyna Hrynkiewicz Agnieszka Ciesielska Ingeborg Haug Christel Baum 《Biology and Fertility of Soils》2010,46(2):139-150
Biotic interactions affect the impact of potential plant growth promoting microorganisms in the rhizosphere, but their magnitude
and fundamentals are often hardly known. In a pot experiment, two physiologically different strains of the ectomycorrhizal
fungus Paxillus involutus (GUL and FRA) were tested separately and in combination with associated bacteria (Sphingomonas paucimobilis 1 L, Ralstonia pickettii 16 B, Sphingomonas sp. 23 L) on their effects on the growth of willows (Salix viminalis). Both P. involutus strains significantly increased the growth of the willows compared with non-inoculated plants, but the magnitude of this
effect was significantly affected by the fungal strain. The P. involutus strain GUL with higher synthesis of auxin-like substances, acid phosphatases, siderophores and faster utilisation of yeast
extract in vitro increased the willow growth in situ more effectively than strain FRA. Additionally, dual inoculation with
the P. involutus strains GUL and FRA in combination with the associated bacteria promoted the willow growth, especially the combination with
S. paucimobilis 1 L. This bacterial strain used effectively C sources which are common components of plant root exudates, e.g. glucose, sucrose,
maltose and mannose as well as compounds synthesized by fungi, e.g. trehalose in vitro. We conclude that the analyses of fungal
metabolites and of C source use of associated bacteria can successfully contribute to accelerate the selection of capable
plant growth promoting combinations. 相似文献
42.
Nancy A. Baum Douglas E. Conklin Ernest S. Chang 《Journal of the World Aquaculture Society》1990,21(4):277-287
Purified diets, formulated with and without lecithin and containing either casein or a protein isolated from whole crab, were fed to juvenile lobsters. In order to examine the role of these dietary factors on cholesterol uptake and transport, levels of cholesterol were determined in serum, lipo-protein fractions, tissues, and feces of juvenile lobsters fed the experimental diets. Lobsters fed diets supplemented with lecithin had significantly higher levels of serum and lipoprotein cholesterol than lobsters fed diets without supplemental lecithin regardless of the proteins used. Levels of fecal total cholesterol also were generally greater for lobsters fed lecithin-supplemented diets. Tissue, serum, and fecal levels of intubated radiolabeled cholesterol, however, were not significantly different among diet groups, and apoprotein electrophoretic mobility was not affected by the choice of dietary protein. 相似文献
43.
Current knowledge on paratuberculosis 总被引:3,自引:0,他引:3
44.
R E Halliwell L L Werner D E Baum C D Newton J H Wolfe H R Schumacher 《Veterinary immunology and immunopathology》1989,21(2):161-175
Rheumatoid factor (RF) was found in titers greater than 1:8 in 72.2% of cases of classical or definite canine rheumatoid arthritis (RA) and in 5.9% or normal sera. Serum fractionation and immunoabsorbant studies that much of the RF present was IgG, although activity was demonstrated in all 3 major immunoglobulin classes. Evidence of involvement of both IgG and IgM to form complexes of varying sizes was obtained. 相似文献
45.
Oidtmann J Schantz M Mäder K Baum M Berg S Betz M Kulozik U Leick S Rehage H Schwarz K Richling E 《Journal of agricultural and food chemistry》2012,60(3):844-851
Bilberries (Vaccinium myrtillus L.) and their major polyphenolic constituents, anthocyanins, have preventive activities inter alia against colon cancer and inflammatory bowel diseases. However, anthocyanins are sensitive to environmental conditions; thus their bioavailability in the gastrointestinal tract is an important determinant of their in vivo activity. In the study reported here, the potential benefits of encapsulating an anthocyanin rich bilberry extract (BE) on anthocyanin stability were investigated. Nonencapsulated BE and three different BE loaded microcapsule systems were incubated in simulated gastric fluid (SGF) and fed state simulated intestinal fluid (FeSSIF). After exposure to these media, released anthocyanins were identified and quantified by HPLC with UV/Vis detection. Although a rapid release of anthocyanins was observed within the first 20 min, encapsulation of anthocyanins doubled the amount of available anthocyanins after 150 min of incubation. These results illustrate the ability of encapsulation to inhibit early degradation of anthocyanins in the intestinal system. 相似文献
46.
Is the ballan wrasse (Labrus bergylta) two species? Genetic analysis reveals within‐species divergence associated with plain and spotted morphotype frequencies 下载免费PDF全文
María QUINTELA Elin Annie DANIELSEN Lua LOPEZ Rodolfo BARREIRO Terje SVÅSAND Halvor KNUTSEN Anne Berit SKIFTESVIK Kevin A. GLOVER 《Integrative zoology》2016,11(2):162-172
The ballan wrasse (Labrus bergylta) is a marine fish belonging to the family Labridae characterized by 2 main morphotypes that occur in sympatry: spotty and plain. Previous studies have revealed differences in their life‐history traits, such as growth and maturation; however, the genetic relationship between forms is presently unknown. Using 20 recently developed microsatellite markers, we conducted a genetic analysis of 41 and 48 spotty and plain ballan wrasse collected in Galicia (northwest Spain). The 2 morphotypes displayed highly significant genetic differences to each other (FST = 0.018, P < 0.0001). A similar degree of genetic differentiation (FST = 0.025, P < 0.0001) was shown using the STRUCTURE clustering approach with no priors at K = 2. In this case, the frequency of spotty and plain morphotypes was significantly different (χ2 = 9.46, P = 0.002). It is concluded that there is significant genetic heterogeneity within this species, which appears to be highly associated with the spotty and plain forms, but not completely explained by them. Given the previously demonstrated biological differences between morphotypes, and the present genetic analyses, we speculate about the convenience of a taxonomic re‐evaluation of this species. 相似文献
47.
ABSTRACT We evaluated direct and interactive effects of light quality and intensity, temperature and light, diurnal rhythms, and timing of high relative humidity during long day lengths on sporulation of Bremia lactucae, the causal agent of lettuce downy mildew, using inoculated lettuce seedlings and detached cotyledons. Suppression of sporulation by light was strongly dependent upon temperature and there was little suppression at =10 degrees C. The most suppressive waveband was in the range from 400 to 450 nm, although a lesser effect of wavebands from 450 to 500 and 500 to 550 nm could be detected. At 15 degrees C, near the lower threshold for suppression of sporulation by light, a clear diurnal pattern of sporulation was observed independent of light and darkness. This diurnal rhythm potentially could interact with light and temperature to confound the results of controlled environment studies, and may be the controlling factor in timing of sporulation at low temperatures. Forecasting models that currently use sunrise and sunset to delimit periods conducive to sporulation can be adapted to short nights and extended twilight conditions by incorporating the effects reported herein. Additionally, models of sporulation could be adapted to better reflect a decrease or absence of the suppressive effect of light at <15 degrees C. 相似文献
48.
Maher?Medini Sonia?HamzaEmail author Ahmed?Rebai Michael?Baum 《Genetic Resources and Crop Evolution》2005,52(1):21-31
Thirty-four durum wheat cultivars representing the Tunisian durum (Triticum durum Desf.) wheat collection and seven wild species of wheat relatives (Triticum turgidum L., T. dicoccon Schrank., T. dicoccoides (Körn) Schweinf., T. araraticum Jakubz., T. monococcum L., Aegilops geniculata Roth, and Aegilops ventricosa Tausch) were analysed with amplified fragment length polymorphism (AFLP) and microsatellite (SSR) markers. Both marker systems used were able to differentiate durum wheat cultivars from the wild relatives and to specifically fingerprint each of the genotypes studied. However, the two marker systems differed in the amount of detected polymorphisms. The 15 SSR markers were highly polymorphic across all the genotypes. The total number of amplified fragments was 156 and the number of alleles per locus ranged from 3 to 24 with an average of 10.4. Two SSR markers alone, Xwms47 and Xwms268, were sufficient to distinguish all 34 durum wheat genotypes. The five AFLP primer pair combinations analysed yielded a total of 293 bands, of which 31% were polymorphic. The highest polymorphic information content (PIC) value was observed for SSRs (0.68) while the highest marker index (MI) value was for AFLPs (7.16) reflecting the hypervariability of the first and the distinctive nature of the second system. For durum wheat cultivars, the genetic similarity values varied between 31.3 and 81% for AFLPs (with an average of 54.2%), and between 3.6 and 72.7% for SSRs (with an average of 19.9%). The rank correlation between the two marker systems was moderate, with r = 0.57, but highly significant. Based on SSR markers, highest genetic similarity (GS) values were observed within the modern cultivars (37.3%), while the old cultivars showed a low level of GS (19.9%). Moreover, the modern cultivars showed low PIC and MI values. UPGMA Cluster analysis based on the combined AFLP and SSR data separated the wild wheat species from the durum wheat cultivars. The modern cultivars were separated from the old cultivars and form a distinct group. 相似文献
49.
50.
The effects of nitrogen fertilization (100, 200 kg N ha−1 per year) and soil properties on mycorrhizal formation on Salix viminalis were investigated at three short rotation plantations on Gleysols and Cambisols (Abbachhof (ABB) and Wildeshausen (WIL) in Germany, Ultuna (ULT) in Sweden). During 3 years the ectomycorrhizal colonization, the composition of ectomycorrhizal morphotypes and the VAM spore density in the soil were analyzed. The ectomycorrhizal colonization was significantly altered due to N-fertilization at all sites. The quality and magnitude of the fertilization effects on mycorrhizal formation on Salix viminalis varied due to the soil properties, i.e. soil texture, soil N content and pH. The WIL site was characterized by sandy soil (low pH, high soil N content), whereas the ABB site was characterized by clayey soil (high pH, low N content). The ULT site was characterized by clayey soil (high pH, high N content). In the unfertilized control plots (C), ectomycorrhizal colonization was higher at WIL than at ABB. Fertilization reduced the ectomycorrhizal colonization at WIL but increased it at ABB. The distribution of the ectomycorrhizal morphotypes was very heterogeneous within the treatments, therefore significant differences were rare. Sporocarps were collected at ABB during one growing period. The sporocarps were mostly from saprophytic species, with exception of the ectomycorrhizal species Inocybe glabripes. Significant effects of N-fertilization on VAM spore density were observed at two of the three plantations. The pattern in VAM spore density was similar to the pattern seen for ectomycorrhizal colonization. Thus, VAM spore density was increased by fertilization at ABB (low soil N) and decreased at ULT (high soil N). The soil properties have been shown to modify the effects of fertilization on ectomycorrhizal colonization and VAM spore density. Therefore, in management practice of short rotation plantations, the benefit of N-fertilization should be evaluated keeping secondary effects caused by changed mycorrhizal formations in mind. 相似文献