首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   308篇
  免费   22篇
林业   20篇
农学   9篇
基础科学   2篇
  64篇
综合类   7篇
农作物   28篇
水产渔业   35篇
畜牧兽医   137篇
园艺   9篇
植物保护   19篇
  2023年   6篇
  2022年   11篇
  2021年   35篇
  2020年   21篇
  2019年   33篇
  2018年   24篇
  2017年   14篇
  2016年   17篇
  2015年   10篇
  2014年   15篇
  2013年   12篇
  2012年   26篇
  2011年   36篇
  2010年   12篇
  2009年   10篇
  2008年   13篇
  2007年   4篇
  2006年   7篇
  2005年   9篇
  2004年   7篇
  2003年   3篇
  2002年   1篇
  2001年   1篇
  2000年   1篇
  1997年   1篇
  1989年   1篇
排序方式: 共有330条查询结果,搜索用时 15 毫秒
91.
92.
The post-operative period can generate immunological stress and can be modulated through supplementation with the omega-3 series of polyunsaturated fatty acids. This study aimed to evaluate the effects of diets enriched with high doses of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids and glutamine on inflammatory mediators in dogs before and after ovariohysterectomy (OVH). Twelve female dogs were divided into two groups: group A was fed a commercial diet without the addition of EPA and DHA, and group B was fed an experimental diet enriched with EPA and DHA (0.2 g/100 kcal). Experimental diet intake initiated 21 days before surgery and continued until 30 days after OVH. Parameters measured were serum cytokines (TNF-α, IL-6 and IL-10), C-reactive protein (CRP), IGF-1, lymphoproliferation and body composition before and after surgery. Statistical analyses were performed with SAS software considering the effects of age and diet and their interactions, and means were compared by the Tukey test. There was no difference between groups in body weight (= .682), lean mass (= .101) and body fat (= .103). There were no group differences in serum concentrations of TNF-α, IL-6, IL-10, IGF-1, CRP and the percentage of lymphocyte proliferation. However, a time effect for TNF-α was observed (< .001), in which T0P (10 days after the surgical procedure) presented lower values of this cytokine when compared to the other evaluation time points; and interaction effects between group and time were observed for serum concentrations of IL-6 (< .001) and IL-10 (= .002). OVH procedure was not considered invasive enough to increase inflammatory cytokines after 30 days of surgery, as well as the dosage of the EPA and DHA used before and after the surgery did not modulate the inflammatory markers.  相似文献   
93.
Metabolic syndrome (MetS) and obesity are growing in many parts of the world, becoming public health problems. It is proposed that foods with functional properties can assist in the treatment of these diseases. Crude buriti pulp oil (BPO) is a food traditionally consumed by residents in the Pantanal, Cerrado and Brazilian Amazon. It is rich in oleic acid, tocopherols and carotenoids, emerging as a potential functional food. Thus, this study aimed to evaluate the effect of the supplementation of BPO on metabolic disorders caused by a high-fat diet. Four groups of C57BL6 mice were used, a lean group with AIN-93M diet and control oil supplementation, an obese group with a high-fat diet and control oil supplementation, and two obese groups with a high-fat diet and BPO supplementation in the amounts of 50 and 100 mg/kg. BPO worsened the metabolic state caused by the high-fat diet, worsening risk factors associated with MetS, as the abdominal circumference and retroperitoneal fat, serum levels of total cholesterol, uric acid, alanine transaminase, glucose and triglycerides, and renal fat, in addition to changes in glycaemic control and oxidative stress markers. C57BL/6 mice fed with a high-fat diet and supplemented with BPO presented a worsening in metabolic risk factors associated with MetS.  相似文献   
94.
Semen cryopreservation is not available for massive use in South American Camelids (SACs) due to the lack of an efficient protocol and the low pregnancy rates obtained with artificial insemination (AI). The use of a single cryoprotectant (CP) is commonly used in SACs frozen semen. The objective of the study was to evaluate the combined cryoprotective capacity of two permeable CPs at different stages of the cryopreservation protocol in llama semen. Sixteen ejaculates from 4 llama males were analysed, and sperm quality was assayed in raw semen, at 5°C, after equilibration of samples with the CPs and when samples were thawed. The following CPs and combination were used: 6% glycerol (GL), 6% dimethylformamide (DMF) and the combination of both CPs: 3% GL and 3% DMF. A Kruskal–Wallis test and an experimental factorial design, considering one factor with four levels (raw semen, 6% GL, 6% DMF and GL/DMF), were used. Total sperm motility and live sperm with intact acrosomes remained unchanged after equilibration of samples (p > .05). A significant decrease in the percentage of functional membrane, motile and live sperm with intact acrosomes was observed when samples were thawed (GL, DMF and GL/DMF). Nevertheless, the cryopreservation protocols used preserved sperm DNA quality; thus, sperm chromatin condensation and DNA fragmentation were unaffected (p > .05) when GL, DMF and GL/DMF were used. To conclude, no superiority was found between the use of a single or a combination of permeable cryoprotectants to freeze llama semen.  相似文献   
95.
The present study was conducted to decipher the proteome of in vivo-produced pre-implantation ovine embryos. Ten locally adapted Morana Nova ewes received hormonal treatment and were inseminated 12 hr after ovulation. Six days later, 54 embryos (morula and blastocyst developmental state) were recovered from eight ewes and pooled to obtain sufficient protein for proteomic analysis. Extracted embryo proteins were analysed by LC-MS/MS, followed by identification based on four database searches (PEAKS, Proteome Discoverer software, SearchGUI software, PepExplorer). Identified proteins were analysed for gene ontology terms, protein clusters and interactions. Genes associated with the ovine embryo proteome were screened for miRNA targets using data sets of TargetScan ( http://www.targetscan.org ) and mIRBase ( http://www.mirbase.org ) servers. There were 667 proteins identified in the ovine embryos. Biological processes of such proteins were mainly related to cellular process and regulation, and molecular functions, to binding and catalytic activity. Analysis of the embryo proteins revealed 49 enriched functional clusters, linked to energy metabolism (TCA cycle, pyruvate and glycolysis metabolism), zona pellucida (ZP), MAPK signalling pathway, tight junction, binding of sperm to ZP, translation, proteasome, cell cycle and calcium/phospholipid binding. Sixteen miRNAs were related to 25 pre-implantation ovine embryo genes, all conserved in human, bovine and ovine species. The interaction network generated by miRNet showed four key miRNAs (hsa-mir-106b-5p; hsa-mir-30-5p; hsa-mir-103a-5p and hsa-mir-106a-5p) with potential interactions with embryo-expressed genes. Functional analysis of the network indicated that miRNAs modulate genes related to cell cycle, regulation of stem cell and embryonic cell differentiation, among others. Retrieved miRNAs also modulate the expression of genes involved in cell signalling pathways, such as MAPK, Wnt, TGF-beta, p53 and Toll-like receptor. The current study describes the first major proteomic profile of 6-day-old ovine embryos produced in vivo, setting a comprehensive foundation for our understanding of embryo physiology in the ovine species.  相似文献   
96.
97.
In the Argentine Chaco, the three species of peccaries (Artiodactyla) are likely affected by habitat destruction and hunting, yet basic information on peccary distribution and status in this region is poorly known. This study identifies human factors associated with relative abundance and distribution of each species. Estimation of relative abundance was based on interviews with local hunters, and variables potentially related to distribution and relative abundance of peccaries were estimated for 153 circular sample sites of 10 km diameter in the Argentine Chaco. Peccaries were found in sites of high forest cover, low human density, far from towns and with low density of roads. After accounting for forest cover and other variables, number of settlements was identified as the main variable negatively associated with relative abundance of the three species, which may be a result of local hunting. Density of roads was also negatively associated with presence of chacoan peccaries. Collared peccary seems to be the least susceptible to human perturbations. It was the most widely distributed and found in a wider range of conditions than the other species. Chacoan peccary was relatively rare. Because colonization and development programs are increasing in the region, areas still uninhabited should be protected, construction of roads controlled, and hunting managed.  相似文献   
98.
  1. Species distribution modelling has been used to identify critical habitats for the delimitation of Marine Protected Areas. Although Marine Protected Areas may often overlap with the distribution of key marine species, illegal human activities often continue within these areas, causing negative impacts on the local biodiversity.
  2. A generalized linear model with spatial eigenvector mapping was used to investigate, for the first time, the influence of environmental variables and anthropic activities on the number of Guiana dolphin, Sotalia guianensis sightings/grid, and to determine whether a Marine Reserve, in south‐eastern Brazil, is adequate for the protection of the local population. Data were collected between May 2007 and October 2013 onboard a 7.5‐m vessel with an inboard engine.
  3. The models for the different periods (annual, dry, and rainy seasons) all indicated that depth, the distance to seafood farms and fishing grounds, and mean sea surface temperatures influenced the distribution of the dolphins within the study area. The annual and seasonal models predicted that the dolphins prefer a continuous area between Cedro and Pico Islands, a large area that lies outside the limits of the Marine Reserve.
  4. Although the habitat of Ilha Grande bay is still much less degraded than that inhabited by other nearby Guiana dolphin populations, the results of the present study indicate that anthropic activities in this area influence habitat use by the dolphins. Less than 30% of the area used by the dolphins is protected by the Tamoios Ecological Station (ESEC Tamoios).
  5. Sotalia guianensis is classified as ‘Vulnerable’ in Brazil, although the marine reserve (ESEC Tamoios) does not protect the core area used by the local dolphin population. The results of the present study provide specific locations for the creation of a new multiple‐use MPA, as suggested by the Brazilian National Action Plan for the Conservation of Small Cetaceans, or the inclusion of a special management programme for the area between Cedro and Pico islands to better protect the dolphins in the ESEC Tamoios buffer zone. The continuation of surveys to better understand the current and future impacts of human activities, and the development of a closer interaction with both the local community and local stakeholders will help to safeguard Ilha Grande Bay and the local Guiana dolphin population.
  相似文献   
99.
Caseinophosphopeptides (CPP) and casein hydrolysates have been shown to bind prooxidant metals such as iron, but their effectiveness as metal chelators to inhibit lipid oxidation in foods has still not been fully investigated. Thus, the antioxidant activity of CPP and casein hydrolysates was studied in phosphatidylcholine liposome model systems. CPP (< 1.0 mg/mL) and casein hydrolysates (0.3-1.7 mg/mL) were effective inhibitors of TBARS development when oxidation was promoted by ferric/ascorbate. High amounts of CPP (> 1.0 mg/mL) were prooxidant, whereas casein hydrolysates were observed to be only antioxidative. In the presence of peroxyl radicals, casein hydrolysates were more effective scavengers than enriched CPP (3-15 mM). In cooked ground beef, TBARS formation was inhibited 75, 39, and 17% by 0.5% enriched CPP, casein hydrolysates, and low molecular weight casein hydrolysates, respectively, after 4 days of storage. The results show that CPP and casein hydrolysates are promising sources of natural antioxidants for foods.  相似文献   
100.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号