全文获取类型
收费全文 | 257篇 |
免费 | 20篇 |
国内免费 | 3篇 |
专业分类
林业 | 20篇 |
农学 | 2篇 |
59篇 | |
综合类 | 52篇 |
农作物 | 11篇 |
水产渔业 | 22篇 |
畜牧兽医 | 49篇 |
园艺 | 3篇 |
植物保护 | 62篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 5篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 13篇 |
2015年 | 3篇 |
2014年 | 7篇 |
2013年 | 13篇 |
2012年 | 11篇 |
2011年 | 23篇 |
2010年 | 7篇 |
2009年 | 5篇 |
2008年 | 7篇 |
2007年 | 9篇 |
2006年 | 12篇 |
2005年 | 11篇 |
2004年 | 1篇 |
2003年 | 7篇 |
2002年 | 4篇 |
2001年 | 9篇 |
2000年 | 6篇 |
1999年 | 7篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 9篇 |
1992年 | 8篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1979年 | 5篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1964年 | 5篇 |
1963年 | 2篇 |
排序方式: 共有280条查询结果,搜索用时 15 毫秒
71.
Huang KJ Wu JJ Chiu YH Lai CY Chang CM 《Journal of agricultural and food chemistry》2007,55(22):9014-9020
This study examines cosolvent-modified supercritical carbon dioxide (SC-CO2) to remove caffeine from and to retain catechins in green tea powder. The response surface method was adopted to determine the optimal operation conditions in terms of the extraction efficiencies and concentration factors of caffeine and catechins during the extractions. When SC-CO2 was used at 333 K and 300 bar, 91.5% of the caffeine was removed and 80.8% of catechins were retained in the tea: 3600 g of carbon dioxide was used in the extraction of 4 g of tea soaked with 1 g of water. Under the same extraction conditions, 10 g of water was added to <800 g of carbon dioxide in an extraction that completely removed caffeine (that is, the caffeine extraction efficiency was 100%). The optimal result as predicted by three-factor response surface methodology and supported by experimental data was that in 1.5 h of extraction, 640 g of carbon dioxide at 323 K and 275 bar with the addition of 6 g of water extracted 71.9% of the caffeine while leaving 67.8% of the catechins in 8 g of tea. Experimental data indicated that supercritical carbon dioxide decaffeination increased the concentrations of caffeine in the SC-CO2 extracts at 353 K. 相似文献
72.
Inbaraj BS Chiu CP Chiu YT Ho GH Yang J Chen BH 《Journal of agricultural and food chemistry》2006,54(17):6452-6459
Poly(gamma-glutamic acid) (gamma-PGA), a nontoxic and biodegradable macropolymer, was evaluated for its efficiency in binding three mutagenic heterocyclic amines (HAs), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-p-2), as affected by pH in a batch mode. The maximum HA sorption was attained for pH 3-7 and decreased sharply for pH less than 3. Binding isotherms obtained at pH 2.5 and 5.5 showed different isotherm shapes that belong to S and L types, respectively. The isotherm data at pH 2.5 were well described by a linear form of the Langmuir equation, while at pH 5.5 it showed two distinct curves, which were precisely fitted as multiple Langmuir curves. The deviation of linearity in Scatchard plot proved the multisite HA sorption. The Brunauer-Emmett-Teller equation also fitted better to isotherm data at pH 5.5, suggesting a multisite sorption caused by multimolecular HA layers on gamma-PGA. High HA sorption levels of 1250, 667, and 1429 mg/g at pH 2.5 and 1429, 909, and 1667 mg/g at pH 5.5 were observed for MeIQ, 4,8-DiMeIQx, and Trp-p-2, respectively. Among the HAs studied, the sorption capacity correlated directly with hydrophobicity of HAs and inversely with the number of methyl groups in HA molecules. The plausible binding mechanism of HAs on gamma-PGA may include a combination of hydrophobic, hydrogen-bonding, ionic, and dipole-dipole interactions. 相似文献
73.
74.
FRM Soto WG Viana GCB Mucciolo FYM Hosomi CI Vannucchi CP Mazzei AR Eyherabide C De Fátima Lúcio RA Dias SS De Azevedo 《Reproduction in domestic animals》2009,44(6):927-931
The aim of this research was to evaluate the efficacy of zinc gluconate associated with dimethyl sulphoxide (DMSO) for chemical neutering in canine males. Fifteen sexually mature male dogs were divided in two groups, named control and treated. An injection was administered to both testicles, at a concentration of 26.2 mg zinc gluconate per ml and 0.5% DMSO in the treated group (11 dogs). The control group was given injections of saline solution (four dogs). Clinical examination and blood collection for a haemogram were done both before and after drug injection. There were 12 spermograms performed to analyse sperm motility, sperm vigour, ejaculate volume, testicle size, pathology and sperm concentrations. Libido was also measured. An ultrasound examination and histopathology were performed at the end of the experiment. Dogs’ libido after chemical injection was reduced by over 50%. The spermogram analysis showed final mean results of 14.54% for sperm motility, 0.72 of sperm vigour and 37 150 per million spermatozoa per millilitre, values considered below the necessary levels at which fertilization can occur. Ultrasound and histopathology analyses of testicles for the treated group revealed more intense injuries when compared with the control group, with compromised testicular parenchyma and a decrease of germ cell number leading to total atrophy, indicating that the treatment reduced the fertilizing potential of male dogs, promoting a possible subfertile status. 相似文献
75.
This study evaluated the effects of priming on emergence responses of purple coneflower (Echinacea purpurea L. Moench) seeds. The seeds that differ in seed size were either primed with moistened vermiculite (solid matrix priming) or primed in non-aerated −0.5 MPa polyethylene glycol 6000 solution at 25 °C for 6 days (osmopriming), followed by air-drying to their initial moisture level. The tetrazolium staining tests indicated that both large and small seeds were biochemically viable. No notable difference in germination percentage was found between large and small seeds. However, extensive cavity was visible in portions of small seeds in comparison with large seeds. Large seeds accumulated more antioxidants and had greater activities of anti-oxidative enzymes than small seeds. They also had greater isocitrate lyase and malate synthase activities than small seeds. As a result, large seeds had higher emergence percentage and faster emergence speed as compared to that of small seeds. Both solid matrix priming and osmopriming increased emergence percentage and shortened mean emergence time of purple coneflower seeds by increasing the activities of anti-oxidative enzymes and decreasing the levels of malondialdehyde and total peroxide accumulation. Moreover, priming also enhanced the anti-oxidative activities of treated seeds. The activities of isocitrate lyase and malate synthase were also increased in primed seeds. The enhanced anti-oxidation and lipid-carbohydrate conversion activities might explain in part why primed purple coneflower seeds emerged better than non-primed seeds. 相似文献
76.
从北京郊区患有类似花叶病害的菜豆株上分离到一种线条状病毒(长约700至750nm)并于1983至1986年间加以研究。在温室内接种可以侵染菜豆、蚕豆、豌豆、大豆、决明、苋色藜及昆诺藜而不能侵染被接种的任何茄科植物.同标准的菜豆普遍花叶病毒(BCMV)相比,它不侵染茄科植物例如黄花烟(Nicotiana rustica)和矮牵牛(Petunia hybrida)在菜豆叶上也不产生坏死枯斑.此外它能侵染蚕豆、大豆、豌豆及决明而BCMV则不能.BCMV能侵染豇豆而这一分离物则不能.此分离物的物理性状为:钝化温度=56-580℃(十分钟),硫释限点=10-3至10-4,180℃下存治期为3天,A260/280=1.12.菜豆受侵叶组织易用光学显微镜观察到内含体包括一种片层叠合体.在电镜下超薄切片中可以看到风轮状体.极易用汁液摩接及用桃蚜(Myzus persic(接种.此病毒的衣壳蛋白亚基的分子量经测定为32,000道尔顿.此病毒与下列病毒即菜豆普通花叶病毒,菜豆黄色花叶病毒,黑眼豇豆花叶病毒,豌豆种传花叶病毒,三叶草黄脉病毒,莴苣花叶病毒及甜菜花叶病毒的抗血清均无反应.由于它在菜豆的"一窝猴"品种的叶片上产生沿脉黄色小点,因此认为这是一种新的独立的病毒,称之为菜豆和性黄色花叶病毒. 相似文献
77.
在田间的小麦丛矮病非典型病株申常常分离到北方禾谷花叶病毒(NCMV)及玉米粗缩病毒(MRDV)两种病原物。单独用前者接种,仅表现小麦丛矮症,单独用后者接种,仅表现小麦蓝矮症,即植株矮化、暗绿、分蘖减少,叶坚挺。两者混合侵染时,往往表现两者的混合症状,但以何种病毒占优势而倾向于优势病毒的症状。典型丛矮症植株中电镜检出弹状病毒粒体,40—70×270—400nm尺度与日本报导的稍异。典型丛矮病株中不存在玉米粗缩病毒的粒体。小麦丛矮病毒很可能是北方禾谷花叶病毒的一种地方性株系。 相似文献
78.
Infectious bursal disease virus (IBDV) causes a contagious immunosuppressive disease in chickens. The aim of the present study is to develop an enzyme-linked immunosorbent assay (ELISA) using the expressed VP2 or VP3 protein of IBDV as the coating antigen for detecting antibodies to IBDV. Experimental results were compared with virus neutralization assay and a commercial-available ELISA. These assays were used to examine the sera from farm chickens and chickens vaccinated experimentally. The VP3-based ELISA had a higher correlation coefficient (R(2)) of 0.812 with a commercial ELISA kit at a serum dilution of 1:500 than that of VP2-based ELISA (R(2)) of 0.671. The relative sensitivity between virus neutralization and VP2-ELISA and VP3-ELISA was 96% (251/262) and 100% (262/262), respectively, and that between virus neutralization and a commercial ELISA was 99% (257/261). Additionally, compared with virus neutralization assay, the reference technique for diagnosing IBDV, VP3-based ELISA had an agreement value of 99%, superior to that of VP2-based ELISA (95%) or the commercial kit (89%). These results revealed that the capability of either VP2-ELISA or VP3-ELISA in detecting the field chicken sera was comparable to the commercial one, which is generally used to replace the virus neutralization assay. However, the preparation of VP3 is derived from an Escherichia coli expression system with a high yield and purification efficiency by Ni(2+)-NTA gels, which is more favorable to the insect cell-derived particles formed by VP2. Therefore, VP3-ELISA could be developed as an efficient and low cost diagnostic method for IBDV infection in field chickens. 相似文献
79.