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   153篇
  免费   4篇
林业   24篇
农学   4篇
  30篇
综合类   8篇
农作物   5篇
水产渔业   19篇
畜牧兽医   54篇
园艺   1篇
植物保护   12篇
  2022年   5篇
  2021年   3篇
  2019年   3篇
  2018年   3篇
  2017年   3篇
  2016年   7篇
  2015年   6篇
  2014年   4篇
  2013年   7篇
  2012年   10篇
  2011年   11篇
  2010年   4篇
  2009年   9篇
  2008年   9篇
  2007年   10篇
  2006年   13篇
  2005年   13篇
  2004年   8篇
  2003年   9篇
  2002年   8篇
  2001年   6篇
  2000年   2篇
  1999年   2篇
  1998年   2篇
排序方式: 共有157条查询结果,搜索用时 16 毫秒
81.
We conducted hydroponic culture experiments to characterize root traits in a rice cultivar ‘Puluik Arang’ that has been identified in a previous study as a cultivar that is adaptable to unflooded conditions. Root morphological traits and the expression of 11 aquaporin genes in rice seedlings (cv. Puluik Arang and cv. Akitakomachi) subjected to osmotic stress by polyethylene glycol (PEG) treatments (10 and 20%) were analysed. ‘Puluik Arang’ exhibited significantly greater water uptake under 10% PEG treatment than ‘Akitakomachi’. Lateral root development was maintained in ‘Puluik Arang’ under PEG treatments. The expression of some aquaporin genes, particularly OsTIP2;1, was higher in ‘Puluik Arang’ than in ‘Akitakomachi’. Immunocytochemical analysis showed that the OsTIP2;1 protein mainly accumulated in endodermal cells. The results suggest that better lateral root development and the function of aquaporins could contribute to water uptake in ‘Puluik Arang’ under osmotic stress.  相似文献   
82.
To clarify the mechanism of seed transmission of Pepper mild mottle virus (PMMoV), the virus was immunolocalized in Capsicum annuum seeds using fluorescence microscopy. Two distinct patterns were observed: In the first, PMMoV was present in the epidermis and parenchyma but not in the endosperm or embryo; in the second, the virus was restricted to the surface of the epidermis and parenchyma. These findings shed light on the fundamental mechanisms of seed transmission of tobamoviruses and may aid in the design of new methods to prevent the spread of seedborne virus diseases.  相似文献   
83.
以软溶质水蜜桃清水白桃为试材,分别在树上完熟的前6、4和2d采样,贮藏于25℃,相对湿度90%的环境条件下至完熟,与树上完熟果实相比较,调查了果实的生理变化、色泽和果汁品质性状,并对完熟果实进行了风味评定。结果表明,贮藏期间的果实乙烯释放量以完熟前2d采收的果实增加最快并在果实完熟时达到最大,树上完熟的果实乙烯释放量最少。树上完熟前6d采收的果实,果皮亮度、果汁的蔗糖含量、“果香型”内酯类物质含量均低于后3次采收的果实,其中以树上完熟前2d采收的果实为最高。相反滴定酸、柠檬酸、天冬酰胺和“清香型”香气物质含量以树上完熟前6d采收的果实最高。完熟果实的风味评定也显示了树上完熟前2d采收的果实综合评价最高,早期采收的果实即使贮藏后达到完熟果肉硬度,甜度和香味少、酸味重。另外,树上完熟的果实肉质粗,酸度低,有怪香味,综合评价不高。  相似文献   
84.
Our previous study indicated the existence of some low molecular weight contaminants in separated fractions (F1 to F4) of alkaline-oxygen stage waste liquor by spectroscopic analysis. In the present study, the quantities of these compounds were determined by capillary electropheresis (CE). Substantial amounts of oxalate and acetate were found in F3. The complexes between Al and oxalate as well as F3 were characterized by 27Al-nuclear magnetic resonance (NMR) spectroscopy, and the spectra of Al-oxalate complexes demonstrated the ability of oxalate to chelate Al and to produce different forms of complexes at varied molar ratios. Plant growth experiments in the presence of Al-oxalate complexes suggested that at a proper range, oxalate has a favorable effect on the detoxification of Al toxicity. It can be assumed that oxalate in F3 also plays an important role in the efficiency of removing Al toxicity. 27Al-NMR was proved to be a useful method for the study of complexes between Al and organic compounds without disturbing their equilibrium conditions.  相似文献   
85.
We examined the ability of chemically modified tannin and tannin-copper complexes to penetrate wood and the ability of the treated wood to resist termites. Only the tannin-treated wood retained the agents after treatment. Wood with untreated mimosa tannin (MT) retained the least amount, followed by wood with resorcinolated tannin (RMT) and that with catecholated tannin (CMT). When RMT or CMT was mixed with ammonia-copper, the wood retained twice as much of these solutions as the MT -ammonia-copper solution. The degree of retention of RMT-NH3-Cu and CMT-NH3-Cu ranged from 268 to 326kg/m3. The solutions penetrated 2–13 mm from the tangential sections of the logs. We also measured the termite resistance conferred by these solutions. Most of the tannin-NH3-Cu solutions showed contact lethality for termites in the contact toxicity test. However, the termites were fed cellulose treated with those solutions and most survived the oral toxicity test (14 days). Moreover, these solutions reduced the amount of damage to the wood by termites. However, the mortality rate of the termites during the eating-damage test (>21 days) did not reach 100% for any of the solutions except for RMT. As a result of the field stake test with the same log's used for the penetrability test, the mass loss of wood treated with RMT or CMT alone or with RMT + NH3 + CuCl2, was about one-third to one-half that of the controls. Because these solutions have good wood penetrability and good termite resistance, they have potential use as low-toxicity wood preservatives.  相似文献   
86.
The effect of acetic acid on the dissolution of proteins in rice was studied to elucidate the mechanism for the textural change induced by the acid by chemical and SDS-PAGE analyses of the rice proteins in the soaking solution. More proteins were extracted with 0.2 M acetic acid (pH 2.7) than with water (pH 6.8). The effect of acetic acid on the protein dissolution increased with increasing temperature. Immunoblotting confirmed that, when rice was soaked in acetic acid, glutelin was dissolved into the soaking solution and degraded by aspartic proteinase. Aspartic proteinase degraded glutelin much more than it did albumin and globulin. It was found that the combined amount of albumin and globulin dissolved into the acetic acid solution was much larger than that of glutelin, despite the smaller amounts present of albumin and globulin than of glutelin. Metal ions were extracted more with acetic acid than with water. In addition, carboxypeptidase was activated under the acidic condition and resulted in an increase in the amount of free amino acids. The main effect of acetic acid on the dissolution of rice proteins was enhancement of the solubility of albumin, globulin, and glutelin, the effect of proteases being minor.  相似文献   
87.
The sales amount of antimicrobials intended for use in dairy cattle, beef cattle and broilers from 2008 to 2019 was evaluated for each antimicrobial class and administration route using dosage-based indicators. Our results revealed that the antimicrobial sales amount sold for use in dairy cattle in 2019 in terms of total weight of active ingredient, the number of defined daily doses (DDDs) (theoretical amount of biomass subjected to antimicrobial treatment in a year) and the number of treatment days (TDs) (theoretical number of days of treatment that an animal is subjected to in a year) calculated using Japanese DDD values (DDDjp values) was 36,751 kg, 8,261,848,000 kg·days and 15.5 days, respectively. Likewise, the antimicrobial sales amount sold for use in beef cattle and broilers in 2019 in terms of these metrics was 33,403 kg, 3,928,248,000 kg·days and 3.61 days, and 69,773 kg, 2,947,848,000 kg·days and 10.66 days, respectively. There was a considerable difference between the number of DDDs calculated using DDDjp values and that calculated using European DDD values (DDDvet values) for antimicrobial products sold for use in dairy and beef cattle. Our results also revealed that the sales amount of some antimicrobials, such as cephalosporins and quinolones represented larger proportions when calculated using dosage-based indicators than when calculated using the weight of active ingredient. Considering that Japanese veterinarians and farmers are more likely to conform to the Japanese dosage recommendations rather than the European ones, these results indicate the need for using dosage-based metrics, in particular metrics based on Japanese dosages rather than European dosages.  相似文献   
88.
89.
In humans, iron (Fe) and zinc (Zn) deficiencies result in major worldwide health problems. Transgenic technologies to produce Fe- and Zn-biofortified rice varieties offer a promising potential solution. Nicotianamine, the precursor of phytosiderophores, chelates Fe2+ and Zn2+ and plays an important role in transporting these metals to both vegetative and reproductive organs within the plant. Our objective was to increase Fe and Zn contents in rice grains by overexpressing the barley nicotianamine synthase gene HvNAS1. HvNAS1-overexpressing transgenic rice showed increased HvNAS1 expression and subsequent increases in endogenous nicotianamine and phytosiderophore content in shoots, roots, and seeds. Fe and Zn concentrations in polished T1 seeds from transgenic plants increased more than three and twofold, respectively; Fe and Zn concentrations also increased in both polished and brown T2 seeds. These results suggest that the overproduction of nicotianamine enhances the translocation of Fe and Zn into rice grains.  相似文献   
90.
Trochodendron aralioides Sieb. et Zucc. and Chloranthus glaber (Thunb.) Makino [Sarcandra globra (Thunb.) Nakai] belong to primitive angiosperms, and are characterized by the absence of vessels. Ephedra sinica Stapf, which is classified in the gymnosperms, contains vessel elements and fiber together with tracheids. Podocarpus macrophyllus (Thunb. Ex Murray) D. Don var. macrophyllus is reported to give a weak positive Mäule test, although it is classified as a gymnosperm. Podocarpus macrophyllus gave only vanillin on alkaline nitrobenzene oxidation, while E. sinica, T. aralioides, and C. glaber gave both vanillin and syringaldehyde. The molar ratio of syringyl to guaiacyl nuclei (S/V ratio) of C. glaber was significantly low (S/V = 0.08) in comparison with the value for T. aralioides (S/V = 1.56). The erythro form is the predominant diasteromeric form of β-O-4 intermonomer linkages of T. aralioides and E. sinica [molar ratio of erythro to threo forms (E/T ratio): 1.93 and 1.67, respectively]; however, P. macrophyllus and C. glaber lignins, of which S/V ratios were 0 and 0.08, gave approximately equal amounts of erythro and threo forms (E/T ratio: 1.01 and 1.14). Results from 1H NMR spectroscopy agree well with S/V ratios of alkaline nitrobenzene oxidation and E/T ratios of ozonation products. In conclusion differences in guaiacyl lignin and guaiacyl-syringyl lignin do not exactly reflect taxonomical differences, as reported in previous articles. It was found that guaiacyl-syringyl lignin is not necessarily linked to the presence of vessels.  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