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   3373篇
  免费   181篇
  国内免费   340篇
林业   333篇
农学   208篇
基础科学   139篇
  684篇
综合类   1346篇
农作物   62篇
水产渔业   586篇
畜牧兽医   264篇
园艺   63篇
植物保护   209篇
  2024年   39篇
  2023年   81篇
  2022年   104篇
  2021年   125篇
  2020年   117篇
  2019年   139篇
  2018年   93篇
  2017年   128篇
  2016年   169篇
  2015年   150篇
  2014年   193篇
  2013年   224篇
  2012年   269篇
  2011年   284篇
  2010年   254篇
  2009年   195篇
  2008年   175篇
  2007年   212篇
  2006年   165篇
  2005年   162篇
  2004年   106篇
  2003年   88篇
  2002年   64篇
  2001年   44篇
  2000年   48篇
  1999年   33篇
  1998年   33篇
  1997年   32篇
  1996年   31篇
  1995年   30篇
  1994年   37篇
  1993年   16篇
  1992年   20篇
  1991年   9篇
  1990年   9篇
  1989年   6篇
  1988年   4篇
  1987年   2篇
  1986年   3篇
  1985年   1篇
排序方式: 共有3894条查询结果,搜索用时 15 毫秒
991.
文章采用离子色谱法,结合在线渗析技术对水产品中多聚磷酸盐的质量分数进行了测定。该方法测定多聚磷酸盐离子在质量浓度0—10.0mg·L-1线性关系良好,相关系数达到0.999。检出限为3.0~10μg·L-1,回收率为95.8%~104%,连续进样检测值相对标准偏差小于10%。试验结果显示该法分离度好,灵敏度高,检测结果准确,操作方便快速,适合水产品中多聚磷酸盐的测定。  相似文献   
992.
Soybean meal (SBM) is one of the most commonly used vegetable ingredient to replace fish meal in fish diets. However, SBM is limiting in some essential amino acids and contains numerous antinutritional factors and antigens that can affect intestinal microbiota and innate immune system in several finfish species and crustaceans and compromise health. The impact of SBM on health and gut microbiota of aquatic animals is not only affected by SBM in general, but also on the degree of treatment of the meal and exposure. Recently, many studies are actively seeking ways to complement or balance those adverse responses induced by high inclusion of SBM in aquaculture diets. These include advanced processing and mixture of feed with other feed components to balance antinutritional factors. The impact of dietary soybean oil on gut microbiota has also been investigated but to a lesser extent than SBM. As the gastrointestinal tract has been suggested as one of the major routes of infection in finfish species and crustaceans, the effect of soybean products on the gut microbiota is important to investigate. Several studies have focus on supplementation of SBM on the adverse responses of the innate immune system as immunological mechanisms are likely involved in the underlying pathology. However, the precise cause of the inflammatory process has not yet been clarified, even though some investigations have suggested that alcohol‐soluble antinutritional factors, especially soy saponins, are potential causative factors. Possible interactions between soybean products and innate immune system in several finfish species and crustaceans are discussed.  相似文献   
993.
Two marine algal products MAP3 and MAP8 were examined for their suitability as fishmeal protein substitutes in feeds of three prominent farmed species, through short‐term feeding studies. Algal meals were tested at 5 and 10% protein replacement levels for Atlantic salmon and at 25 and 40% for common carp and whiteleg shrimp. At the end of the 12‐week period, the growth and feed performance of the two fish species did not reveal any significant difference between those fish offered the algae‐based feed and those offered the control feed. The whole body proximate compositions of Atlantic salmon fed the control and algae‐based feeds were not significantly different. In common carp, the lipid content in the fish fed higher level of MAP3 was significantly lower than that of the fish fed the control feed. In whiteleg shrimp, at the end of the 9‐week feeding period, growth performance and feed utilization did not differ between the treatment groups. Protein content in the shrimp fed the higher level of MAP8 was significantly lower than that of shrimp on the control feed. The three species could accept the algal meals in their feeds at the tested levels, though there were some noticeable effects on body composition at higher inclusion levels.  相似文献   
994.
黄连素对3种水产动物致病菌的抑制作用研究   总被引:1,自引:0,他引:1  
文章研究了黄连素对副溶血弧菌(Vibrio parahaemolyticus)、溶藻弧菌(V.alginolyticus)和嗜水气单胞菌(Aeromonas hydrophila)等3种致病菌的最小抑菌浓度(MIC)和最小杀菌浓度(MBC),检测了黄连素对病原菌菌体形态和生长曲线的影响,并以此解析黄连素对这3种致病菌的抑制特点和抑菌机制.结果显示,黄连素对副溶血弧菌、溶藻弧菌、嗜水气单胞菌的MIC和MBC分别为0.391 mg·mL^-1和0.391 mg·mL^-1、0.391 mg·mL^-1和0.781 mg·mL^-1、0.781 mg·mL^-1和1.563 mg·mL^-1,说明黄连素对3种致病菌均有明显的抑制作用,其中对副溶血弧菌的抑制效果最佳.同步结果显示,1.00 mg·mL^-1黄连素不仅会严重破坏致病菌的菌体形态,而且使致病菌的迟缓期延长2~7h,这暗示黄连素可能通过影响致病菌的细胞结构和生长繁殖来达到抑菌的效果.由此可见,黄连素在防治水产类细菌性疾病上有很好的应用潜力.  相似文献   
995.
This study reports the in vitro activity of six antimicrobial peptides (AMPs) produced by aquatic animals (most marine invertebrates): tachyplesin (Tach), magainin (Mag), clavanin (Clav), penaeidin (Pen), mytilin (Myt) and antilipopolysaccharide factor (ALF) against marine vibrios, filamentous fungi and yeast. Their stability under salinity conditions and seawater was also examined. The results showed that Mag, Myt and especially Tach and ALF (minimum inhibitory concentration<1.5 μM) had a potent activity against all tested vibrio species, whereas Clav and Pen were ineffective (up to 50 μM). With respect to the antifungal activity, each AMP had a different potency according to the fungal species. In general terms, Tach was the most potent peptide, followed by Mag. Interestingly, Tach, Myt and ALF had a significant effect on the filamentous fungus Fusarium solani that could be pathogenic to marine organisms. All AMPs had a tendency to decrease or lose their activity at high salinity (>225 mM NaCl). Tach and Myt were the most stable peptides, maintaining significant activity under seawater salinity (450 mM). Curiously, all peptides lost their effect under seawater conditions. The results suggest that Tach, ALF and Myt are the most promising candidates for potential therapeutic use in farmed-marine species, because all have a significant and broad antimicrobial activity maintained at high salinity.  相似文献   
996.
核苷酸(Nucleotide,NT)是细胞的主要组分,又是构成DNA和RNA的单体,具有调节生物体内能量代谢、参与遗传信息编码、传递细胞信号等重要的生理和生化功能[1]。由于动物机体能合成各种核苷酸,而且又没有特异的缺乏症,因而长期  相似文献   
997.
邱伟强  陈刚  陈舜胜  谢晶 《水产学报》2011,35(11):1745-1752
建立了水产品中6种ATP关联化合物的离子对反相高效液相色谱(IP-RPLC)检测方法,确定了缓冲液的最佳pH、流速和浓度,并对方法的准确度、精确度和检测限进行了测定.采用10%的高氯酸分离提取样品,用KOH溶液中和后进行HPLC分析.采用Waters 2695色谱系统,Thermo ODS-2 Hypersil(250 mm ×4.6 mm,5μm)色谱柱,柱温为25℃;以10%甲醇,90% 0.05 mol/L磷酸盐溶液为流动相,磷酸盐溶液含9 mmol/L四丁基氢氧化氨(TBA),并用1 mol/L的磷酸调pH至6.5,采用等度洗脱,流速为0.9 mL/min;检测波长为254 nm.结果表明:6种ATP关联化合物在13 min内完全分离;在2~400 μg/mL范围内线性关系良好,相关系数在0.9994~1.0000之间;方法最低检测限(信噪比S/N =3)在0.1~0.4 μg/mL之间;加标平均回收率为82.2% ~110.0%,相对标准偏差为4.2% ~9.5%.本方法可用于水产品中ATP、ADP、AMP、IMP、Hx和HxR等6种ATP关联化合物的同时测定和分析.  相似文献   
998.
王茵  吴成业 《福建水产》2011,33(1):82-85
本文从企业规模、技术创新、对台合作等方面综合评价了厦门市水产品加工业的发展现状,分析了目前面临的问题及存在的不足,在此基础上提出相应的对策.建议提高加工技术及科技含量、拓展新产品和新工艺、实施品牌战略、提高资源利用率、发展来进料加工、提高水产品安全质量等,为促进厦门市水产品加工业整体水平的提高建言献策.  相似文献   
999.
高通量测序分析凡纳滨对虾育苗期水体菌群结构特征   总被引:7,自引:2,他引:7  
为了解凡纳滨对虾育苗期正常苗池水体菌群结构和多样性变化,实验采用Illumina MiSeq高通量测序水体细菌16S rDNA V4区,比较幼体在无节V期(N5)、溞状Ⅱ期(Z2)、糠虾Ⅰ期(M1)与仔虾Ⅰ期(P1)时的水体菌群特征。结果显示,水体菌群Shannon多样性指数随幼体发育先降后升,而Pielou均匀度指数除在N5时稍高外,在其余阶段都很接近。育苗期间,变形菌门为水体绝对优势菌群(50.0%~88.0%),尤其红杆菌科从N5到P1阶段分别占24.2%、61.6%、43.3%和51.8%;拟杆菌门在各期丰度均9.7%,其中腐螺旋菌科以5.3%~16.9%优势分布于后3个阶段;放线菌门在后3个期都为优势类群,并以微杆菌科为主,丰度分别达5.6%、37.6%和10.8%;而疣微菌门只在P1时表现为优势(5.3%)。苗池水体核心菌属主要由洛克氏菌、海命菌、栖东海菌、亚硫酸杆菌和2个分类未定属构成。可见水体菌群呈高度多样而动态变化,且N5菌群明显区别于后3个阶段。育苗期间水体主要环境因子总体波动较小,对优势操作分类单元(OTU)丰度分布无显著影响。研究表明,凡纳滨对虾健康苗池水体菌群随幼体发育和饵料投喂而明显更替,其中核心菌群的潜在功能对维持水体生态系统稳定起重要作用,可为对虾育苗益生菌与健康苗池指示菌的筛选提供依据。  相似文献   
1000.
介绍了玉米蛋白粉的营养价值,综述了在饲料中使用玉米蛋白粉对水产动物生长、原料表观消化率、饲料适口性、饲料氨基酸平衡、鱼体生化指标、肌肉成分以及养殖水环境的影响,初步探讨了改善水产动物对玉米蛋白粉利用率的途径,提出应加强不同水产动物就玉米蛋白粉在体内的代谢、对养殖水环境的影响、对机体抗病免疫力和肌肉风味的影响以及玉米蛋白粉对除鱼粉外的动物蛋白源的替代研究。  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