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   128篇
  免费   7篇
林业   4篇
农学   11篇
基础科学   6篇
  33篇
综合类   3篇
农作物   30篇
水产渔业   10篇
畜牧兽医   31篇
园艺   1篇
植物保护   6篇
  2022年   3篇
  2021年   4篇
  2020年   7篇
  2019年   7篇
  2018年   10篇
  2017年   10篇
  2016年   6篇
  2015年   3篇
  2014年   3篇
  2013年   19篇
  2012年   5篇
  2011年   13篇
  2010年   10篇
  2009年   6篇
  2008年   11篇
  2007年   5篇
  2006年   3篇
  2005年   2篇
  2004年   1篇
  2003年   1篇
  2000年   1篇
  1997年   1篇
  1996年   1篇
  1990年   1篇
  1984年   1篇
  1960年   1篇
排序方式: 共有135条查询结果,搜索用时 742 毫秒
71.
This study was conducted to evaluate the Salvia officinalis hydroalcoholic extract on fertility capacity and behavioral features in rats exposed to immobilization stress. Male rats were randomly divided into five groups; Control; Stressed rats; and Stressed rats received 50, 100 and/or 200 mg/kg bw S. officinalis hydroalcoholic extract. To induce stress, rats were immobilized for 49 days and received S. officinalis extract orally. On day 56, we analyzed behavioral tests and evaluated reproduction capacity by measuring LH, FSH, and testosterone. Sperm parameters such as motility, viability, and total count were also determined. Bodyweight changes were also calculated on day 56. Male rats from different groups were mated with healthy female rats. Data showed that the use of 100 and 200 mg/kg bw S. officinalis extract in stressed rats increased bodyweight gain and improved behavioral disorders compared to control‐matched groups (p < .05). Besides, administration of 100 and 200 mg/kg bw S. officinalis extract had the potential to improve sperm parameters and fertility capacity in stressed rats (p < .05). Decreased testosterone levels were blunted in the stressed rats that received plant extract coincided with the reduction of LH and FSH compared to control‐matched stressed rats (p < .05). We found neutral effects in stressed rats that received 50 mg/kg bw plant extract. Collectively, the hydroalcoholic extract of S. officinalis could improve the fertility capacity and behavioral features under stressful conditions in a dose‐dependent manner.  相似文献   
72.
Background : The emergence and propagation of different phylogenetic groups of antimicrobial-resistant E. coli have become a worldwide health concern in human and veterinary medicine. Therefore, the evaluation of the phylogenetic distribution of antibiotic-resistant E. coli is important for therapeutic and economic purposes. The aims of this study were to determine phylogenetic groups and patterns of antibiotic resistance of E. coli strains isolated from human urinary tract infection and avian colibacillosis. Methods: A total of 50 E. coli isolates (25 from human urinary tract infection and 25 from avian colibacillosis) were characterized by culture and assigned as different phylogenetic groups (A, B1, B2, and D) by triplex PCR assay. Kirby-Bauer disk diffusion method was used to assess the susceptibility of all isolates to ten antibiotics. Results: Results showed that the majority of the human and poultry isolates belonged to phylogenetic groups A and B2 and phylogenetic group B1 of the avian pathogenic strain isolates were the most drug-resistant isolates. Most of the isolates were resistant to at least five antibiotics, and multiple drug resistance was observed in 98% of E. coli isolates. A high degree of resistance was seen against penicillin and erythromycin. Conclusion: According to the results of this study, multidrug-resistance among isolates and high relation between phylogenetic groups and resistance in both human and poultry isolates were observed. Key Words: Escherichia coli, Avian colibacillosis, Phylogenetic grouping  相似文献   
73.
A greenhouse experiment was conducted to evaluate the effects of foliarly-applied Humic Acid (HA) and Salicylic Acid (SA) on strawberry (Fragaria × Ananassa cv. Camarosa). On average, HA applications, regardless of concentration, increased overall yield, Soluble Solids Concentrations (SSC), Titratable Acidity (TA), vitamin C, red tone (a*), leaf potassium (K), phosphorus (P), calcium (Ca) and magnesium (Mg) while had no effect on pH and fruit luminosity (L*). In contrast, fruit from the untreated control tended to have higher Total Antioxidant Capacity (TAC) and SSC: TA ratio than HA-treated plants. Application of SA significantly increased yield, vitamin C, SSC, SSC: TA ratio, TAC, a*, leaf P and Ca while had no effect on TA, fruit size, L* and pH. In general, application of either HA at 25 mg L1 or SA at 2 mM resulted in better strawberry performance than did other rates of these compounds.  相似文献   
74.
Local farmers who living in South Kalimantan (Banjarese farmers) apply almost none of phosphatic (P) fertilizers to grow local rice varieties. This practice has been adopted for many years. We have investigated the mechanisms involved in P availability for the crop. This study focuses on identifying microorganisms involved in solubilizing insoluble P. The study was conducted in Balandean District, South Kalimantan, Indonesia. The soil was classified as acid sulfate soil. Three out of 8 rice varieties grown were selected for net P balance in the soil-plant system and the microbial studies. We found that the P uptakes by the rice crop was much higher than the sum of P released from soil, water and soil microbial biomass P. It was also observed that these soils harboured bacteria and fungi that have the capability of dissolving aluminium phosphate (AIPO4) and tricalcium phosphate [Ca3(PO4)2].
Based on the area of clear zone on plates, it seem that there were variations of ability in dissolving Al-P or Ca-P. DNA sequence analysis shown that Burkholderia sp. was the common P solubilizing bacterium found in the rhizosphere of rice varieties Siam Unus, Siam Ubi and Siam Puntal. The presence of other bacteria was specific for each rice variety grown.  相似文献   
75.
In the mammalian CNS, N-methyl-D-aspartate (NMDA) receptors serve prominent roles in many physiological and pathophysiological processes including pain transmission. For full activation, NMDA receptors require the binding of glycine. It is not known whether the brain uses changes in extracellular glycine to modulate synaptic NMDA responses. Here, we show that synaptically released glycine facilitates NMDA receptor currents in the superficial dorsal horn, an area critically involved in pain processing. During high presynaptic activity, glycine released from inhibitory interneurons escapes the synaptic cleft and reaches nearby NMDA receptors by so-called spillover. In vivo, this process may contribute to the development of inflammatory hyperalgesia.  相似文献   
76.
77.
The glucosinolate (GSL) pattern of 93 resynthesized (resyn) repeseed lines was examined over three years, and five stable genotypes with distinct GSL profiles were identified. Typically the resyn B. napus profile exhibited progoitrin as the main GSL, but contained sinigrin. The different GSL patterns of the four deviating lines are discussed with respect to the proposed biosynthetic pathway. Within the resyn and further extensive breeding materias, screening for low indolyl GSL contents resulted in finding one genotype with an extremely low 4-hydroxy-gluco-brassicin and glucobrassicin content. Furthermore, other lines were identified, over a wide range of indolyl GSL contents. The values were stable over two years.  相似文献   
78.
The larger the bulk density of the soil, the smaller the saturated hydraulic conductivity (Ks), however, the relationship between Ks and dry bulk density for tilled and untilled conditions is different. Ks is lower in tilled soil than in untilled soil with the same texture at the same bulk density. The purpose of this study was to compare different models for the prediction of Ks for two soil textures under both tilled and non-tilled conditions. We compred two models based on the non-similar media concept (NSMC-0, NSMC-1), a model based on the similar media concept (SMC) and a model based on the Kozeny equation and Poiseuille law for prediction of Ks (KC-1 and KC-2). This study was conducted at two areas with loam and silty clay loam soils under tilled and untilled conditions. It is concluded that the SMC model is not able to predict Ks under either tilled or untilled conditions. Further, the NSMC-0 model, along with an equation to estimate the shape factor, was able to predict Ks versus dry bulk density for tilled soils. According to our study, under untilled conditions, the KC-1 and NSMC-1 models, and under tilled conditions, the NSMC-1 and NSMC-0 models, predicted Ks accurately. It is concluded that the NSMC models together with the optimized Kozeny–Carman models could reliably be used to predict Ks in different soil textures.  相似文献   
79.
In order to improve feeding and growth of juvenile great sturgeon Huso huso, the effects of various lipid sources in feed were examined. Three hundred juveniles (initial body weight 215 ± 10 g) were distributed into 15 flow-through 1100 l tanks (20 fish per tank). Five experimental diets containing various lipid levels were formulated: diet C (control; without added oil), SO(L) and SO(H) diets containing soybean oil concentrations respectively, (53.5 vs. 174 g/kg), FO(L) and FO(H) diets containing fish oil with low and high concentrations respectively (53.5 vs. 174 g/kg). Fish were fed three times daily based on their appetite for a period of 6 weeks. At the termination of the experiment, growth rate was improved with increasing oil content in the diets. There were significant differences in final weights among fish fed the different experimental diets. Lipid content of muscle and liver significantly increased with increasing dietary lipid levels for both soybean and fish oil. The lowest cholesterol level and the highest haematocrit value were measured in fish fed the FO(H) diet. No significant difference was found among dietary treatments in terms of triacylglycerol concentration, number of red blood cell, mean corpuscular volume, mean corpuscular haemoglobin (MCH) and MCH concentration (MCHC). According to the most growth indices, results of this study suggest that the best results were observed in FO(H) which can be attributed to the greater palatability of diet containing high fish oil, supply of fatty acid requirement and enhanced physiological performance.  相似文献   
80.
Corn (Zea mays L.) is an important source of protein for humans and animals. Because dent corn is highly responsive to nitrogen (N) fertilization, substantial amounts of N are used for corn production. Application of N fertilizer may reduce protein quality of corn kernels through an increase in zein content. The objective of this study was to determine if corn endosperm characteristics influence the effect of N fertilization on protein quality. In 1988, six corn hybrids differing for endosperm characteristics were grown at two locations in Ohio and with two N rates, 34 and 200 kg/ha. The waxy hybrid had a greater concentration of fraction I protein than the non‐wary hybrid. These two hybrids did not differ for other fractions except fraction III at Columbus. The soft endosperm hybrid had a higher concentration of fraction I protein than the hard endosperms hybrids. Soft and hard endosperm hybrids differed for fraction II protein for the 34 kg N/ha fertilizer rate but not the 200 kg N/ha fertilizer rate. These two classes of hybrids did not differ for fraction III protein. Increasing N fertilizer increased fraction II concentration for all hybrids. Concentrations of the other two protein fractions did not respond to fertilizer rate. The increase in fraction II concentration with N fertilization may result in a decrease of protem quality and feed value. Although all hybrids responded to N fertilizer, some hybrids had bigger increases in fraction II proteins than other hybrids.  相似文献   
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