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   369篇
  免费   18篇
  国内免费   27篇
林业   12篇
农学   59篇
  8篇
综合类   170篇
农作物   70篇
水产渔业   21篇
畜牧兽医   42篇
园艺   19篇
植物保护   13篇
  2020年   2篇
  2019年   5篇
  2018年   3篇
  2017年   10篇
  2016年   11篇
  2015年   10篇
  2014年   8篇
  2013年   13篇
  2012年   20篇
  2011年   29篇
  2010年   29篇
  2009年   23篇
  2008年   29篇
  2007年   30篇
  2006年   21篇
  2005年   22篇
  2004年   14篇
  2003年   14篇
  2002年   14篇
  2001年   20篇
  2000年   12篇
  1999年   6篇
  1998年   7篇
  1997年   5篇
  1996年   6篇
  1995年   6篇
  1994年   4篇
  1993年   4篇
  1992年   5篇
  1991年   3篇
  1990年   7篇
  1989年   2篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1985年   8篇
  1984年   5篇
  1983年   4篇
排序方式: 共有414条查询结果,搜索用时 15 毫秒
11.
The storage protein profiles of the seeds of two IITA cowpea cultivars (‘IT84E–124’ and ‘Vita 7’) exposed to three mutagens—sodium azide (NaN3), ethyl methane sulphonate (EMS) and 60Co gamma rays—and those of 18 selected M3 lines were investigated by sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis (PAGE). The total seed protein, globulin and albumin fractions showed differences in number and intensity of subunit bands, but the least differences were found in the albumin fraction. Both high and low molecular weight bands were observed, the highest being 94.5 kDa and the lowest 12.0 kDa.‘Vita T showed less variability compared with ‘IT84E–124’, as indicated by the relative similarity indices (S.I.) of the two cultivars. The lowest S.I. of 0.200 was found among ‘IT84E–124’ lines while the lowest S.I. among ‘Vita T lines was 0.4706. A number of lines with particular traits were found to be characterized by the presence of specific polypeptide bands. This study demonstrates that induced mutation could create additional variability to supplement existing germplasm and that SDS-PAGE is a useful tool for discriminating and estimating genetic similarities among selections.  相似文献   
12.
13.
旨在得到一套快速提取椰子DNA的方法。采用CTAB小样法、SDS-CTAB法以及PVP法提取椰子组织的DNA,并通过后续的PCR扩增和酶切等实验比较了3种方法所提取的DNA质量的优劣。将CTAB小样法提取的DNA与SDS-CTAB法和PVP法提取的DNA进行了比较,CTAB小样法提取的DNA的OD260/OD280(1.839)较另外2种方法SDS-CTAB法(1.709)和PVP法(1.613)的值更高,CTAB小样法提取的DNA适合于PCR扩增,扩增的条带清晰,且特异性好。此外,CTAB小样法提取的DNA,酶切也较为均匀。CTAB小样法能高效地提取椰子的DNA,并且能一次提取大量的高质量DNA样品,因而能满足高通量的实验要求,同提取DNA能较好地满足下游的分子生物学研究。  相似文献   
14.
The hydrolysis efficiency of excess sludge by the two surfactants (SDS and SDBS) was investigated according to COD dissolution rate, concentrations of soluble carbohydrate and soluble protein. The results showed that the hydrolysis of excess sludge was improved by using the two surfactants. When the dosage was in low range, SCOD concentration increased significantly with dosage increasing. But the increase of SCOD was not obvious when the dosage was higher than 50 mg/g dw. SCOD concentration increased from 638.5 mg/L to 6 446.8 mg/L (SDBS) and 4 857.2 mg/L (SDS) respectively. COD dissolution rate increased from 5.8% to 37.3%(SDBS) and 30.2%(SDS) respectively. With the increase of SDS and SDBS dosage in the range of 0~150 mg/g dw, the concentrations of the soluble protein and carbohydrate increased linearly. Soluble carbohydrate increased from 3.54 mg/L to 95.56 mg/L(SDBS) and 64.20 mg/L(SDS) respectively. Soluble protein concentration increased from 11.72 mg/L to 706.30 mg/L(SDBS) and 541.08 mg/L(SDS) respectively. The concentrations of ammonia and VFA also increased with the SDS and SDBS dosage. Ammonia concentrations increased from 4.21 mg/L to 130.33 mg/L(SDBS) and 102.74 mg/L(SDS) respectively. VFA concentrations increased from 21.27 mg/L to 358.30 mg/L(SDBS) and 283.12 mg/L(SDS) respectively.  相似文献   
15.
为探讨高产杂交稻两优培九在衰老过程中,剑叶光合膜蛋白质复合物的含量变化规律及其与光能吸收、转化、传递的关系,以大田栽培自然衰老剑叶为材料,利用活体叶绿素荧光动力学技术,并结合类囊体膜蛋白质复合物蓝绿温和胶电泳分析。结果表明,两优培九剑叶叶绿素含量、光合性能、类囊体膜蛋白稳定性等都在抽穗期达到顶峰,随后开始衰退,在扬花期、灌浆期尚保持较高水平,而进入籽粒成熟阶段衰退明显;随着衰老进程,光合膜蛋白质复合物有序非同步降解,稳定性为LHCII > PSIIcore > PSIcore > ATPase & Cyt b6/f > LHCI;PSI和PSII蛋白和相应电子传递活性的稳定性及下降幅度差异较大;衰老过程叶绿素a/b的不断下降与相对于反应中心更稳定的捕光天线有关,剑叶生长后期LHCII维持高水平保持了叶片对光能的吸收,并可能在调节光系统间能量分布和协助过剩能量耗散中起重要作用。  相似文献   
16.
Seed longevity is a very important characteristic controlling seed quality. However, the mechanism underlying this characteristic is poorly understood. In this study, 'FH7185', a storable rice variety, the germination rate of which was 66.63%, much higher than the control after artificial ageing under relative humidity 88% and 42°C for 21 days. Different methods were applied to reveal the involvement of proteins during ageing of rice seeds. In total, 35 differential proteins were identified from 2D‐PAGE, and 3,719 proteins from iTRAQ analysis. A comparison of these two methods showed that not all protein types could be detected on the 2D‐PAGE gels, and the dynamic range was somewhat limited. So the comprehensive proteome map from the iTRAQ analysis was used to identify the quantitatively regulated proteins that played roles in seed longevity, and found that the most marked change was the increased abundance of many metabolic enzymes, especially the ones involved in α‐linolenic acid metabolism in the embryos during ageing. OsLOX2 and OsLOX3 had a negative effect on seed longevity, which were lower in FH7185 than the control. The dehydrogenase (LOC_Os07g44430) which played a major catalytic role in lipid peroxidation, also changed significantly during ageing. Therefore, OsLOX2, OsLOX3 and Loc_OS 07G44430 may be involved in the regulation of seed longevity with a synergistic effect.  相似文献   
17.
本研究以36个陕西省主要栽培品种为材料,利用SDS-PAGE方法分析了高分子量麦谷蛋白亚基组成,并对其SDS沉淀值进行了测定,分析了高分子量麦谷蛋白亚基组成与代表面包烘烤品质的SDS沉淀值间的关系.结果表明:Glu-1位点存在着广泛的等位基因变异,在所分析的36个品种中,Glu-A1位点亚基1出现频率最高,为63.9%;Glu-B1位点等位基因变异最丰富,其中亚基7 8和7 9出现频率最高,其次为亚基14 15;Glu-D1位点亚基组成以2 12为主;对各位点品质评分与SDS沉淀值的简单相关分析结果表明各位点品质评分与SDS沉淀值均存在着显著或极显著相关关系,各位点影响大小依次为Glu-D1>Glu-A1>Glu-B1;Glu-1品质评分与SDS沉淀值极显著正相关.  相似文献   
18.
几种内生真菌DNA提取方法的比较   总被引:12,自引:2,他引:12  
通过三种内生真菌DNA提取方法的比较,即CTAB法、SDS法、改良的CTAB法,结果表明三种方法都能得到目的DNA,而且得率都不错,但改良的CTAB法效果最好,DNA纯度高且质量也好。用改良的CTAB法所提取的DNA作为模板,进行PCR扩增,得到了清晰的单一的扩增普带,完全可用于酶切、测序等后续实验。  相似文献   
19.
籼稻体细胞胚胎发生特异性蛋白质研究   总被引:3,自引:0,他引:3  
方继朝  薛庆中 《作物学报》1994,20(4):395-400
以籼稻Oryza sativa L.subsp. indica品种“广陆矮4号”幼穗和种子为外植体,在含有2,4-D2.0mg/L的MS培养基上,分别形成胚性和非胚性愈伤组织,建立体细胞胚胎发生实验系统。应用Native/SDS双向凝胶电泳分析,结果表明,非胚性愈伤组织分化培养前后均存在一种分子量为45kD的非胚性蛋白质N1,另一种非胚性蛋白质N2(54kD)仅  相似文献   
20.
不含 SBTI-A_2的基因导入我国大豆的遗传表达   总被引:5,自引:0,他引:5  
大豆 Glycine max(L.)Merrill 种子中的主要营养抑制因子是 Kunitz 胰蛋白酶抑制剂(SBTI—A_2)。经利用标准 SBTI 比较谱带的聚丙烯酰胺凝胶电泳(PAGE)分析方法,证实了我国栽培大豆中豆19、临沂81-551、通县元豆、中作84-C_(42)和中作84-C_(02)均属 Ti~aTi~a 型。并利用上述5个黄淮海夏大豆品种或品系与美国不含 SBTI-A_2(titi)品系 L_(81-4590)和 L_(83-4387)杂交,在7个组合的 F_2代中得到了 titi 型。其表型比例为3∶1,符合孟德尔单基因遗传规律。进一步的研究正在进行中。  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