全文获取类型
收费全文 | 134篇 |
免费 | 6篇 |
专业分类
林业 | 17篇 |
农学 | 7篇 |
基础科学 | 2篇 |
20篇 | |
综合类 | 3篇 |
农作物 | 7篇 |
水产渔业 | 9篇 |
畜牧兽医 | 54篇 |
园艺 | 6篇 |
植物保护 | 15篇 |
出版年
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 4篇 |
2017年 | 7篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2013年 | 12篇 |
2012年 | 12篇 |
2011年 | 10篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 2篇 |
2007年 | 7篇 |
2006年 | 5篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1992年 | 1篇 |
1988年 | 1篇 |
排序方式: 共有140条查询结果,搜索用时 46 毫秒
41.
Amphibian populations have declined and disappeared in protected and apparently undisturbed areas around the world, especially in montane areas of the tropics. The amphibian chytrid fungus, Batrachochytrium dendrobatidis has been implicated in many of these declines. In Costa Rica most declines occurred in the highlands. We examined an amphibian collection made in Braulio Carrillo National Park in 1986 for the amphibian chytrid fungus B. dendrobatidis, prior to the well documented amphibian declines in Monteverde, along an altitudinal transect from 100 to 2600 m elev. Skin from the pelvic patch of 202 specimens corresponding to 30 species was examined histologically to determine whether the disease was present in the highlands of the park before amphibian populations declined. For comparison, in 2002 we collected and examined 18 specimens of seven species of Eleutherodactylus and Craugastor from two other lowland Caribbean sites. The chytrid fungus was present in almost all altitudes in 1986, including lower areas. The pathogen was also found in both species that later declined and in species that did not do so. We detected chytrid fungus on amphibians collected at almost all altitudes in 1986, including those sampled at 280 m. B. dendrobatidis was abundant in frogs collected in the 2002 survey, and seems to be endemic in most of Costa Rica. More retrospective museum surveys are needed in order to determine whether it can be found in the area before 1986. 相似文献
42.
de Miranda e Silva Chaves Camila da Costa Ricardo Lopes Dias Duarte Keila Maria Roncato Beltrame Renato Travassos Quirino Celia Raquel 《Tropical animal health and production》2020,52(3):1345-1349
Tropical Animal Health and Production - The early pregnancy diagnosis allows optimizing production and timely management correction, with a greater reproductive output of livestock. The Idexx Rapid... 相似文献
43.
Felipe André Sganzerla Graichen José Antônio Martinelli Caroline de Lima Wesp Luis Carlos Federizzi Márcia Soares Chaves 《European journal of plant pathology / European Foundation for Plant Pathology》2011,131(3):497-510
Crown rust, caused by Puccinia coronata f. sp. avenae, can cause significant damage in all regions where oats (Avena sativa L.) are cultivated. The primary means of controlling crown rust has been through genetic resistance, although in most cases
resistance has been quickly overcome by the pathogen. More durable partial or non-specific resistance may possess different
mechanisms from those underlying genes with specific effects. We studied the epidemiological and histological components of
crown rust resistance with potential use in plant protection. Among the components evaluated, pustule density showed the clearest
effect on resistance, while the latent period was not an important component. Cell death associated with the accumulation
of autofluorescent and phenolic compounds was common in the resistant genotypes, but temporally distinct for the genotypes
studied. Genotype Pc68/5*Starter, which has race-specific resistance, showed rapid cell death that prevented the development
of pathogen colonies. Conversely, with cultivar URS 21 and genotypes 04B7113-1 and 04B7119-2, cell death and associated accumulation
of autofluorescent and phenolic compounds was delayed until pathogen colonies were already established. Pathogen colonies
developed normally in susceptible plants genotypes, and had usually produced sporogenic tissue by 5 days after inoculation.
The data suggest that the resistance mechanisms, especially hypersensitivity and phenolic compound production, active in resistant
plants are similar but may be differently expressed over time. The temporal variation in the expression of hypersensitivity
and phenolic compound production reflects the level of field resistance in these genotypes. 相似文献
44.
M. Vaz J. Maroco N. Ribeiro L. C. Gazarini J. S. Pereira M. M. Chaves 《Agroforestry Systems》2011,82(2):173-181
We studied morphological, biochemical and physiological leaf acclimation to incident Photon-Photosynthetic-Flux-Density (PPFD) in Quercus ilex (holm oak) and Quercus suber (cork oak) at Mediterranean evergreen oak woodlands of southern Portugal. Specific leaf area (SLA) decreased exponentially with increasing PPFD in both species. Q. ilex had lower SLA values than Q. suber. Leaf nitrogen, cellulose and lignin concentration (leaf area-based) scaled positively with PPFD. Maximum rate of carboxylation (Vcmax), capacity for maximum photosynthetic electron transport (Jmax), rate of triose-P utilization (VTPU) and the rate of nonphotorespiratory light respiration (Rd) were also positively correlated with PPFD in both Quercus species, when expressed in leaf area but not on leaf mass basis. Q suber showed to have higher photosynthetic potential (Vcmax, Jmaxm and VTPUm) and a higher nitrogen efficient nitrogen use than Q.ilex. Leaf chlorophyll concentration increased with decreasing PPFD, improving apparent quantum use efficiency (Φ) in both Quercus species. We concluded that, in Q.ilex and Q.suber, leaf structural plasticity is a stronger determinant for leaf acclimation to PPFD than biochemical and physiological plasticity. 相似文献
45.
Romani S Sacchetti G Chaves López C Pinnavaia GG Dalla Rosa M 《Journal of agricultural and food chemistry》2000,48(8):3616-3619
Since to our knowledge no data are available in the literature regarding the influence of green coffee type and origin on ochratoxin A (OTA) content, determinations were carried out in order to assess the level of OTA contamination in green coffee samples of different provenience. A total of 162 samples of green coffee beans from various countries (84 from Africa, 60 from America, and 18 from Asia) were analyzed for OTA. Both the amount and the variability of OTA levels were tested as a function of green coffee provenience. The results showed that 106 of the overall samples were positive for OTA, with concentration ranging from 0 to 48 microg/kg (ppb). In particular, it was possible to verify that African samples were more contaminated with respect to samples of other origin in terms of frequency and level of OTA; the highest concentrations observed were 18 and 48 microg/kg in two samples from The Congo. 相似文献
46.
Paulo Cesar Pazdiora Rosane Lopes Crizel Keilor da Rosa Dorneles Sabrina Monks da Silva Thomas Natali Morello Fabio Clasen Chaves Leandro José Dallagnol 《Plant pathology》2023,72(1):53-66
A three-year field experiment with two wheat cultivars evaluated the effect of soil-applied silicon (Si), with and without fungicide spraying, on Fusarium head blight (FHB) control. Silicon treatment alone reduced FHB severity and the percentage of damaged wheat kernels, regardless of the cultivar. The best disease control was obtained for the cultivar with moderate disease resistance (MR), supplied with silicon and treated with fungicide during flowering. Silicon treatment alone promoted an increase in deoxynivalenol (DON) concentration in the disease-susceptible cultivar; however, in the MR cultivar, silicon amendment associated with fungicide treatment led to a reduction in DON concentration. Greenhouse experiments evaluated the effect of silicon combined with different timings of fungicide application on wheat defences against Fusarium graminearum. Plants supplied with silicon had a longer pathogen incubation period, lower FHB severity and lower DON concentration when compared to plants without silicon. In addition, silicon-supplied plants had higher soluble phenolic content and altered antioxidant enzyme activities (SOD, CAT, POX and PPO) that favoured early accumulation of hydrogen peroxide when compared to plants without silicon. Greater control of FHB and lower DON concentration in plants treated with silicon and fungicide before inoculation and up to 1 day after inoculation was associated with increased levels of defence-associated metabolites. Silicon contributed to the reduction of FHB and DON concentration in wheat, especially for the MR cultivar and, when combined with fungicide spraying, both MR and disease-susceptible cultivars had enhanced performances upon silicon amendment. 相似文献
47.
Martínez Pastur Guillermo José Cellini Juan M. Chaves Jimena E. Rodríguez-Souilla Julián Benitez Julieta Rosas Yamina M. Soler Rosina M. Lencinas María V. Peri Pablo L. 《Agroforestry Systems》2022,96(7):1039-1052
Agroforestry Systems - Sustainable forest management is proposed as a solution for many ecological and socio-economic trade-offs associated with different forest uses. In Patagonia, silvopastoral... 相似文献
48.
Patrícia Aparecida Cardoso da LUZ Paulo Ramos da Silva SANTOS Cristiana ANDRIGHETTO André Mendes JORGE Ant?nio Chaves de ASSIS NETO 《The Journal of reproduction and development》2013,59(1):14-17
Buffalo are an economically important source for meat and milk production, especially in
Brazil. However, important aspects of their biology remain unknown thus far. Herein, we
describe the reproductive characteristics of male Murrah buffalo (Bubalus
bubalis) raised under extensive management conditions by applying biometrics
associated with testicular weight. We analyzed seven males, divided into two groups: G1,
which consisted of four 18-month-old animals, and G2, which consisted of three
24-month-old animals. Testicular development occurs slowly in Murrah buffalo, suggesting a
delay of sexual maturity. The biometric testicular parameters analyzed were scrotal
circumference, testicular weight, testicular length, testicular width, testicular
thickness and testicular circumference. Our data indicate strong correlations between SC,
age and body weight, and additional significant relationships were identified between body
weight, age and other testicular parameters. Thus, these parameters are suitable
indicators when selecting bulls for breeding purposes. 相似文献
49.
Ariel Vicente Bernardo Repice Gustavo Martínez Alicia Chaves Pedro Civello 《The Journal of Horticultural Science and Biotechnology》2013,88(2):246-251
SummaryMature boysenberries (Rubus hybrid) were harvested, heat-treated (45°C for 1 or 3 h or 47°C for 1 h) or exposed to UV-C light (2.3, 4.6 or 9.2 kJ m–2), and stored at 20°C for 2 d. Fruit treated with 9.2 kJ m–2 or 45°C for 1 h showed less damaged drupelets per fruit and/or remained firmer than untreated fruit after 2 d. Those treatments were selected for further analyses. In another experiment, boysenberries were either UV-C (9.2 kJ m–2) or heat-treated (45°C for 1 h) and stored either at 20°C for 1 d or at 0°C for 4 d before transfer to 20°C for 1 d. Both UV-C and heat treatments reduced softening and/or fruit damage. Treated fruit had lower respiration rates and anthocyanin leakage than control fruit suggesting greater tissue integrity. Titratable acidity, pH, total sugar content and antioxidant activity in treated fruit showed fewer changes than in control fruit when stored at 20°C for 1 d. Results suggest that heat or UV-C treatment, alone or in combination with refrigerated storage, may be a useful non-chemical mean of maintaining boysenberry fruit quality and extending postharvest life. 相似文献
50.
Renan O. Silva Ana Paula M. Santana Nathalia S. Carvalho Talita S. Bezerra Camila B. Oliveira Samara R. B. Damasceno Luciano S. Chaves Ana Lúcia P. Freitas Pedro M. G. Soares Marcellus H. L. P. Souza André Luiz R. Barbosa Jand-Venes R. Medeiros 《Marine drugs》2012,10(12):2618-2633
Red seaweeds synthesize a great variety of sulfated galactans. Sulfated polysaccharides (PLSs) from seaweed are comprised of substances with pharmaceutical and biomedical potential. The aim of the present study was to evaluate the protective effect of the PLS fraction extracted from the seaweed Gracilaria birdiae in rats with naproxen-induced gastrointestinal damage. Male Wistar rats were pretreated with 0.5% carboxymethylcellulose (control group—vehicle) or PLS (10, 30, and 90 mg/kg, p.o.) twice daily (at 09:00 and 21:00) for 2 days. After 1 h, naproxen (80 mg/kg, p.o.) was administered. The rats were killed on day two, 4 h after naproxen treatment. The stomachs were promptly excised, opened along the greater curvature, and measured using digital calipers. Furthermore, the guts of the animals were removed, and a 5-cm portion of the small intestine (jejunum and ileum) was used for the evaluation of macroscopic scores. Samples of the stomach and the small intestine were used for histological evaluation, morphometric analysis and in assays for glutathione (GSH) levels, malonyldialdehyde (MDA) concentration, and myeloperoxidase (MPO) activity. PLS treatment reduced the macroscopic and microscopic naproxen-induced gastrointestinal damage in a dose-dependent manner. Our results suggest that the PLS fraction has a protective effect against gastrointestinal damage through mechanisms that involve the inhibition of inflammatory cell infiltration and lipid peroxidation. 相似文献