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   75篇
  免费   4篇
林业   7篇
农学   3篇
  17篇
综合类   1篇
农作物   13篇
水产渔业   7篇
畜牧兽医   19篇
园艺   9篇
植物保护   3篇
  2022年   1篇
  2021年   1篇
  2020年   3篇
  2018年   3篇
  2017年   5篇
  2016年   4篇
  2015年   5篇
  2014年   2篇
  2013年   5篇
  2012年   6篇
  2011年   3篇
  2010年   5篇
  2009年   4篇
  2008年   3篇
  2007年   3篇
  2006年   6篇
  2005年   5篇
  2004年   4篇
  2003年   1篇
  2002年   4篇
  2001年   1篇
  2000年   3篇
  1999年   1篇
  1988年   1篇
排序方式: 共有79条查询结果,搜索用时 163 毫秒
71.
72.
Desorption of NH3 from wastewater in a laboratory scale aerated lagoon was investigated. Landfill leachate of around 575 mg L?1 NH3-N was used as the wastewater. The pH was raised to above 11.0 to achieve almost 100 conversion of NH+ 4 to NH3. The study quantifies the percentage NH3 desorbed at the free liquid surface and that desorbed into the air bubbles. Theoretical calculations and practical observations showed that between 15 to 38% of the total NH3 that was lost could be accounted for by desorption into the air bubbles. The rest of the NH3 desorption was at the upper liquid surfaces. The main role of the air bubbles is to create surface turbulence; NH3 desorption into the bubbles is of secondary importance.  相似文献   
73.
Persia is one of the main origin centers of pomegranate; hence, a diverse germplasm has evolved in the area over the past centuries. This study was conducted to evaluate the physico-chemical properties of fruits of ten Persian pomegranate cultivars. The plants used for this experiment had been collected from different parts of Iran and were established in a repository. Wide variations in the main properties of the ripe fruits of the cultivars were observed. The size, weight, skin thickness and weight, and juice content of the fruits were within the range of 55.14–71.76 mm, 98.55–199.40 g, 1.07–3.93 mm, 28.96–66.95 g, and 2.00–89.33 ml, respectively. Seed weight, Aril numbers, fresh and dry weight of 100 arils were 33.80–72.90 g, 170.70–570.30, 23.16–42.82 g, and 17.22–33.87%, respectively. The levels of total anthocyanin, total soluble solids (TSS), titrable acidity (TA), ascorbic acid, total phenolics, electrical conductivity, and TSS/TA ratio were ranged between 5.91–180.70 mg/100 g, 9.35–13.93 °Brix, 0.16–2.28%, 7.15–1061 mg/100 ml, 3578–5108 mg/100 g, 2.51–4.93 dS/m, and 4.09–80.34, respectively. The results emphasized on the role of plant genotype on fruit taste parameters, bioactive compounds, and yield. The variations in the fruits indicated differences in nutritive quality, which may satisfy diverse consumer acceptance in different areas. Moreover, it provides great opportunities for improving crop yield and quality.  相似文献   
74.
Background:Variations in mtDNA-CN of PBLs, as a potential biomarker for GC screening has currently been subject to controversy. Herein, we have assessed its efficiency in GC screening, in parallel and in combination with sPG I/II ratio, as an established indicator of gastric atrophy. Methods:The study population included GC (n = 53) and non-GC (n = 207) dyspeptic patients. The non-GC group was histologically categorized into CG (n = 104) and NM (n = 103) subgroups. The MtDNA-CN of PBLs was measured by quantitative real-time PCR. The sPG I and II levels and anti-H. pylori serum IgG were measured by ELISA. Results:The mtDNA-CN was found significantly higher in GC vs. non-GC (OR = 3.0; 95% CI = 1.4, 6.4) subjects. Conversely, GC patients had significantly lower sPG I/II ratio than the non-GC (OR = 3.2; CI = 1.4, 7.2) subjects. The combination of these two biomarkers yielded a dramatic amplification of the odds of GC risk in double-positive (high mtDNA-CN-low sPGI/II) subjects, in reference to double-negatives (low mtDNA-CN-high sPGI/II), when assessed against non-GC (OR = 27.1; CI = 5.0, 147.3), CG (OR = 13.1; CI = 2.4, 72.6), or NM (OR = 49.5; CI = 7.9, 311.6) groups. Conclusion:The combination of these two biomarkers, namely mtDNA-CN in PBLs and serum PG I/II ratio, drastically enhanced the efficiency of GC risk assessment, which calls for further validations. Key Words: Biomarkers, DNA copy number variation, Mitochondrial DNA, Stomach neoplasms  相似文献   
75.
Abstract.— Two studies were conducted to evaluate the potential use of limnocorrals (in situ enclosures) for evaluating the effects of phytotoxic compounds on phytoplankton community structure and water quality. Limnocorrals consisted of open‐bottomed, fiberglass cylinders that were 2.44 m in diameter and 1.53 m high. The enclosures were placed in an aquaculture pond and allowed to settle 10–20 cm into the bottom mud, forming a watertight seal that isolated approximately 5.5 m3 of pond water. The first study evaluated the effect of water mixing on environmental conditions within limnocorrals. Mixing was accomplished by injecting air through airstones suspended inside the enclosures. Conditions in unmixed limnocorrals rapidly deviated from conditions in the pond and in aerated enclosures, with overall phytoplankton biomass decreasing while abundance of cyanobacteria and concentrations of soluble reactive phosphorus increased. Conditions in limnocorrals with continuous mixing also deviated from conditions in the pond. Environmental conditions among replicate mixed enclosures were, however, relatively consistent and stable for at least 2 wk. The second study evaluated the use of limnocorrals for testing the effects of phytotoxic compounds on phytoplankton community structure and water quality. A commercial chelated copper algicide was added to randomly selected, mixed limnocorrals at the label‐recommended rate. The algicide killed nearly all phytoplankton in the treated enclosures within 1 wk; however, treated limnocorrals were rapidly recolonized by green algae and diatoms. Conditions in untreated limnocorrals remained relatively stable and consistent among replicates for 16 d, after which total phytoplankton biomass began to decrease, possibly due to nutrient depletion within the enclosures. Although conditions inside the enclosures deviated with time from those in the surrounding pond water, mixed limnocorrals appear to provide a convenient and reliable method for short‐term studies of algicides and other water quality manipulations.  相似文献   
76.
77.
Lack of basic knowledge about spatial and treatment varying crop response to irrigation hinders irrigation management and economic analysis for site-specific agriculture. One model that has been postulated for relating crop-specific economic quantities to irrigation is a quadratic response curve of yield as a function of irrigation. Although this model has far reaching economic interpretations it does not account for spatial variation or possible nitrogen-irrigation interactions. To this end we propose a spatially treatment varying coefficient model that alleviates these limitations while providing measures of uncertainty for the estimated coefficient surfaces as well as other derived quantities of interest. The modeling framework we propose is of independent interest and can be used in many different applications. Finally, an example involving site-specific agricultural data from the U.S. Department of Agriculture-Agricultural Research Service demonstrates the applicability of this methodology.  相似文献   
78.
79.
BACKGROUND: Teucrium polium is an analgesic, antidiabetic and antilipeidemic herbal medicament. The aim of this survey was to evaluate the effect of aqueous extract T. polium on liver enzymes linked to liver dysfunction, serum lipids and glucose, in diabetic male rats. METHODS: A total of 20 Sprague-Dawly male rats became diabetic by intraperitoneal injection of streptozotocin (60 mg/kg). the animals were divided randomly into two groups. Experimental group was fed Teucrium polium (50 mg/kg) for a month but control group was received the same volume of distilled water. Liver enzymes, biochemical parameters (cholesterol, triglyceride, low density lipoprotein, alanine transaminase, aspartae transaminase) and glucose were measured by kinetic (Enzymatic) and colorimetric methods. Data obtained were analyzed and mean values were compared by paired student's t-test. The results were expressed as mean +/- SD. Significant differences were set at P < 0.05. RESULTS: Our results showed that in test group, serum glucose values decreased significantly (P < 0.05), but cholesterol, triglyceride, low density lipoprotein, alanine transaminase and aspartae transaminase increased significantly after use of T. polium (P < 0.05). This parameters value did not show any changes in control group. CONCLUSION: Although the aqueous extract of Teucrium polium has strong hypoglycemic properties in experimental animals, but because of some hepatotoxic effects, it is not suitable to use it in human as an antidiabetic agent.  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