全文获取类型
收费全文 | 105篇 |
免费 | 5篇 |
专业分类
林业 | 14篇 |
农学 | 3篇 |
基础科学 | 1篇 |
36篇 | |
综合类 | 2篇 |
农作物 | 12篇 |
水产渔业 | 6篇 |
畜牧兽医 | 21篇 |
园艺 | 4篇 |
植物保护 | 11篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 5篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 7篇 |
2013年 | 6篇 |
2012年 | 3篇 |
2011年 | 11篇 |
2010年 | 5篇 |
2009年 | 6篇 |
2008年 | 5篇 |
2007年 | 9篇 |
2006年 | 1篇 |
2005年 | 3篇 |
2004年 | 1篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1996年 | 1篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有110条查询结果,搜索用时 78 毫秒
81.
Agustín Olmedo-Juárez Rolando Rojo-Rubio Alejandro Zamilpa Pedro Mendoza de Gives Javier Arece-García María Eugenia López-Arellano Elke von Son- de Fernex 《Veterinary research communications》2017,41(3):227-232
The aim of this study was to evaluate the in vitro lethal effect of a hydroalcoholic extract (HAE) from Acacia cochliacantha leaf against three gastrointestinal nematodes species (Haemonchus contortus, H. placei and Cooperia punctata) of domestic ruminants. The HAE was assessed using five concentrations: 100, 125, 175, 150 and 200 mg/ml; 0.5% Ivermectin was used as a positive control and distilled water, as negative control. The data were normalized using the square root and analysed with a completely randomized design through ANOVA analysis using the general lineal model (GLM) of the SAS program. The HAE tannin content was determined through spectrophotometry (UV-visible) and the other major phenols, were identified by chromatographic processes. The results showed an in vitro larvicidal activity of the HAE against the three assessed nematode species with all assessed concentrations. A clear HAE increased concentration dependence effect was observed. The highest activity of the HAE was obtained at the highest concentration (close to 100%, P < 0.05). This result was similar to the one obtained with Ivermectin. On the other hand, the chemical analysis of HAE showed the presence of tannins, caffeoyls and coumaroyl derivates and quercetin as the main compounds. The results suggest that the HAE from this plant species possess in vitro anthelmintic properties. The identified compounds in this study would good candidates for further in vivo researches. 相似文献
82.
J. M. Cachinero F. Cabello J. Jorrin M. Tena 《European journal of plant pathology / European Foundation for Plant Pathology》1996,102(4):401-405
Chitinase and-1,3-glucanase activities were assayed in roots, hypocotyls and cotyledons of downy mildewsusceptible and -resistant sunflower (Helianthus annuus L.) cultivars. While the highest-1,3-glucanase activity was in roots, that of chitinase activity was in hypocotyls. Inoculation of both sunflower cultivars withPlasmopara halstedii resulted in a marked increase of chitinase and-1,3-glucanase activities. The increase was observed earlier in incompatible than in compatible reactions. Both enzymes occurred in root tissue as a complex mixture of isoenzymes. At least three different peaks with chitinase activity and three with glucanase activity could be resolved by gel filtration chromatography on Sephacryl S-100 and chromatofocusing on PBE 94 (pH 7-4). Following ammonium sulfate precipitation and ion-exchange on CM- and DEAE-Trisacryl, three glucanase and chitinase fractions, referred to as basic, neutral and acidic, were separated on the basis of their Chromatographic behaviour. A different pattern of distribution of chitinase and-1,3-glucanase fractions was observed between inoculated and non-inoculated plants in both resistant (cv. RS-105) and susceptible (cv. Peredovik) cultivars. In healthy plants-1,3-glucanase was mainly found in the basic (cv. Peredovik) and neutral (cv. RS-105) fractions, whereas chitinase was in the basic fraction for both cultivars. The neutral and acidic fractions of chitinases were induced in the compatible and incompatible reactions. Inoculation of the plants induced the neutral-1,3-glucanase fraction in resistant and susceptible cultivars and the acidic only in the susceptible one. Induction of the basic fraction of both activities was not observed in any case. 相似文献
83.
Alfredo F. Ojanguren Felipe G. Reyes-Gavilán Rolando Rodríguez Muñoz 《Aquaculture International》1999,7(2):81-87
Three embryonic stages of Atlantic salmon (Salmo salar L.) were subjected to eight constant incubation temperatures (4, 7, 10, 12, 14, 16, 19 and 22 °C) exceeding the range usually experienced in natural conditions. A change in thermal tolerance during the embryonic and larval development was registered: pre-hatching stages showed an upper thermal limit at about 16 °C, while hatched larvae survived until 22 °C. Temperature significantly affects developmental rate, resulting in a faster development and, consequently, lower yolk weight percentage at higher temperatures. We found positive relationships between incubation temperature and body size (length and weight) in the less developed stages, in which some yolk remained, but size decreased at increasing temperatures when yolk was completely exhausted. 相似文献
84.
Benjamín Ramírez-Wong C. E. Walker Ana I. Ledesma-Osuna Patricia I. Torres Concepción L. Medina-Rodríguez Guadalupe A. López-Ahumada María G. Salazar-García Refugio Ortega-Ramírez A. M. Johnson Rolando A. Flores 《Cereal Chemistry》2007,84(3):207-213
Wheat flours commercially produced at 74, 80, and 100% extraction rates made from hard white winter wheat (WWF) and hard red winter wheat (WRF) were used to produce tortillas at a commercial-scale level. Flour characteristics for moisture, dry gluten, protein, ash, sedimentation volume, falling number, starch damage, and particle-size distribution were obtained. Farinograms and alveograms were also obtained for flour-water dough. A typical northern Mexican formula was used in the laboratory to test the tortilla-making properties of the flours. Then commercial-scale tortilla-baking trials were run on each flour. The baked tortillas were stored at room and refrigeration temperatures for 0, 1, 2, and 3 days. Maximum stress and rollability were measured every day. Tortilla moisture, color, diameter, weight, and thickness were measured for each treatment. Finally, tortilla acceptability was tested by an untrained sensory panel. Analyses of variance (ANOVA) were performed on the data. WWF had higher protein content, dry gluten, sedimentation volume, and water absorption than the WRF. The WWF was the strongest flour based on farinograph development time and alveograph deformation work. It also produced the most extensible dough measured with the alveograph (P/L). Flour protein and ash contents, water absorption, and tenacity increased directly with the flour extraction rate. Both WWF and WRF performed well in commercial-scale baking trials of tortillas. Tortillas made with both types of flours at 74 and 80% extraction rates had the best firmness and rollability. However, tortillas made with WWF 80% had the best color (highest L value). Tortillas prepared with 100% extraction rate flour were also well accepted by the sensory panel, had good textural characteristics, and became only slightly firm and slightly less rollable after three days of storage at room temperature. 相似文献
85.
To investigate the effects of mechanically damaged starch and flour particle size on the texture of fresh and stored flour tortillas, two commercial hard red winter wheat flour samples were reground four times using decreasing roll gaps. Tortillas were made with a modified hot‐press procedure. Texture characteristics were measured after tortillas were stored 2 hr (fresh tortilla), 2 days, and 4 days. Damaged starch and particle size significantly affected (P < 0.05) flour water absorption, dough extensibility and resistance, and dough viscosity. As damaged starch increased and particle size decreased, the flour tortillas became less stretchable, the maximum force of Kramer shear decreased, and firmness and rollability increased. The effects of damaged starch and particle size on stretchability and Kramer shear were greater in fresh tortillas than in stored tortillas and became smaller as the storage time increased. However, the effects of damaged starch and particle size on rollability and firmness were smaller in fresh tortillas than in stored tortillas but became greater as the storage time increased. 相似文献
86.
Birds can serve as useful model organisms to investigate community level consequences of forestry practices. In this study
we investigated the relationships between wintering bird communities and habitat and landscape characteristics of lowland
managed forests in Northern Italy. This area is characterized by the spread of the black locust, an alien species that has
been favored by forestry practices at the expense of natural oak forests. Birds were censused in winter by point counts in
randomly selected plots of 50 m radius. We first addressed bird community–habitat relationships by means of habitat structure
measurements, then we investigated bird community–landscape relationships by using GIS techniques. We used generalized linear
models (GLM) to test for the effects of habitat and landscape variables on bird community parameters (namely bird species
richness, diversity and abundance). Bird community parameters were influenced by oak biomass and tree age, and by oak area
and core area, while the other forest habitat types showed less influence. In forest management terms, the main conclusion
is that the retention of native oaks is the keyfactor for the conservation of winter bird diversity in local deciduous woods.
At the habitat level black locust harvesting may be tolerated, provided that old, large, native oaks are retained in all local
woodlots to preserve landscape connectivity and foraging resources. At the landscape meso-scale, large native oak patches,
should be preserved or, where necessary, restored.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
87.
Ayako Toma María Botero Omary Kurt A. Rosentrater Elizabeth A. Arndt Naruemon Prasopsunwattana Sutida Chongcham Rolando A. Flores Sylvia P. Lee 《Cereal Chemistry》2008,85(6):721-729
Consumption of whole grains as part of a health‐promoting diet is encouraged among Americans due to beneficial nutrients and phytochemicals. The main objectives of this study were to investigate the effect of whole barley flour particle size on consumer acceptance of whole grain and soluble fiber‐enriched tortillas; to examine the effect of demographic and behavioral data on consumer acceptance; and to establish relationships between consumer acceptance and survey results to identify market opportunities among particular groups of consumers. Four experimental tortillas and two representative commercial brands were tested by 95 untrained panelists using a 9‐point hedonic scale for appearance, color, flavor, texture, and overall acceptability. Demographic and behavioral data on age, gender, ethnicity, frequency of tortilla consumption, daily effort to include fiber in the diet, consumption of tortillas containing ≥1 g of dietary fiber/serving, consumption of low‐fat tortillas, and tortilla brands and type used were collected. Potential market segments for these tortillas include older consumers (41+), women, Hispanics, and Asians, and frequent tortilla consumers. A response surface relating flavor and texture to overall acceptability produced almost equivalent results to the multivariate PLS results in terms of predicting overall acceptability, which facilitates analysis and interpretation. 相似文献
88.
Texture is a property of major importance in the evaluation of baked products. To determine a sample of commercial ranges for stretchability, rollability, firmness, and Kramer shear cell measurements for wheat flour tortillas using the TA‐XT2 texture analyzer, three separate sets of five tortilla brands purchased from stores in Manhattan, KS, were evaluated. Two brands had two formulations, regular and fat‐free. Significant differences (P < 0.05) in stretchability, firmness, and Kramer shear cell occurred between regular and fat‐free tortillas of one tortilla brand. Significant differences (P < 0.05) also were found among the sets of some tortilla brands. Kramer shear cell and stretchability measurements are recommended because Kramer shear cell measures the force combined with compression, shearing, and extrusion. Stretchability measurements were repeatable and are an important textural property of wheat flour tortillas. Ranges for textural properties for commercial wheat flour tortillas were determined, as well as the variability of the textural methods used. 相似文献
89.
Two herbicides used for post‐plant weed control in commercial forests in New Zealand, terbuthylazine and hexazinone, are not endorsed for use on land certified by the Forest Stewardship Council (FSC). These herbicides are effective for controlling competitive woody weeds, such as Cytisus scoparius (broom). To investigate the potential of non‐residual, alternative herbicides for the control of C. scoparius after planting, a range of treatments were implemented at two trials. The trials were established in newly planted Pinus radiata plantations where C. scoparius dominated. The objectives were to (i) optimise application rates of alternative herbicides and compare their efficacy to current practice and (ii) identify if treatment efficacy varied across sites. Treatments at each site included weedy and weed‐free controls, current practice using terbuthylazine and hexazinone, applied as both spot treatment and broadcast application, and a range of new treatments consisting of different dosage combinations of clopyralid, triclopyr and picloram. Broadcast application of the clopyralid, triclopyr and picloram mixture showed increasing weed‐control efficacy against C. scoparius with increasing dose rate, resulting in increased tree volume. Broadcast application of the clopyralid, triclopyr and picloram mixture at 75% or 100% of a typical industry use rate (100% industry rate includes clopyralid 1.5 kg a.i. ha?1, triclopyr 0.15 kg a.i. ha?1 and picloram 0.05 kg a.i. ha?1) achieved greatest tree volume by year four with tree volumes exceeding that obtained using the operational spot treatment with terbuthylazine and hexazinone. Treatment rankings were similar between locations. The result supports the use of clopyralid, triclopyr and picloram to control C. scoparius during the first year of P. radiata establishment. 相似文献
90.
Francisco Encina‐Montoya Rolando Vega‐Aguayo Alfonso Mardones‐Lazcano Teresa Rueda Alfredo Tello 《Aquaculture Research》2011,42(6):835-843
Galaxias maculatus is an osmeriform native fish of the Southern Hemisphere, in which the crystalline larvae is considered as a luxury delicacy, for this reason, it has been commercially exploited in Chile, Argentina and New Zealand. However, the fisheries have been rapidly decreasing due to the overexploitation and the predation of introduced species. Because of these events, there is a need to determine a carrying capacity for an intensive fish culture. In order to optimize stocking densities for fish culture, this paper proposes objectives to determine oxygen consumption (OC) rates, dissolved oxygen concentrations that produce signs of hypoxia and the average time elapsed between food intake and peak OC in G. maculatus. In the oxygen experiments under routine metabolism conditions, we found that G. maculatus adults and whitebait showed signs of asphyxia at dissolved oxygen concentrations between 1.3 and 2.2 mg L?1 and that adults tolerated dissolved oxygen levels as low as 1.3 mg L?1. The results showed that G. maculatus individuals with an average weight of 0.04 g consumed 0.048 mg O2 h?1, whereas individuals with an average weight of 1.4 g consumed 0.345 mg O2 h?1. Galaxias maculatus increased the OC rate by 31%, from 0.39 to 0.51 mg O2 h?1 g?1, occurring 14 min after food intake. The carrying capacities for industrial cultures of G. maculatus, were estimated using an allometric equation (OC=0.2363 ×W 0.612 ), a water flow rate of 1 m3 h?1 and an input oxygen concentration of 10 mg L?1 at 12 °C. The density culture of whitebait (4 g) can be allowed to reach 8–11 kg m?3; therefore, these stocking densities reduce the risk of hypoxia and mortality, ensuring the appropriate growth and feed conversion rates. 相似文献