全文获取类型
收费全文 | 2016篇 |
免费 | 132篇 |
国内免费 | 7篇 |
专业分类
林业 | 200篇 |
农学 | 62篇 |
基础科学 | 24篇 |
498篇 | |
综合类 | 249篇 |
农作物 | 86篇 |
水产渔业 | 166篇 |
畜牧兽医 | 604篇 |
园艺 | 56篇 |
植物保护 | 210篇 |
出版年
2023年 | 11篇 |
2022年 | 22篇 |
2021年 | 33篇 |
2020年 | 47篇 |
2019年 | 61篇 |
2018年 | 49篇 |
2017年 | 55篇 |
2016年 | 63篇 |
2015年 | 51篇 |
2014年 | 65篇 |
2013年 | 112篇 |
2012年 | 148篇 |
2011年 | 149篇 |
2010年 | 104篇 |
2009年 | 90篇 |
2008年 | 140篇 |
2007年 | 122篇 |
2006年 | 114篇 |
2005年 | 95篇 |
2004年 | 109篇 |
2003年 | 116篇 |
2002年 | 102篇 |
2001年 | 27篇 |
2000年 | 26篇 |
1999年 | 20篇 |
1998年 | 14篇 |
1997年 | 18篇 |
1996年 | 13篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 8篇 |
1992年 | 11篇 |
1991年 | 13篇 |
1990年 | 10篇 |
1989年 | 10篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 10篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1974年 | 5篇 |
1967年 | 3篇 |
1958年 | 3篇 |
排序方式: 共有2155条查询结果,搜索用时 62 毫秒
1.
2.
Acquired resistance triggered by elicitins in tobacco and other plants 总被引:17,自引:0,他引:17
Philippe Bonnet Eva Bourdon Michel Ponchet Jean -Pierre Blein Pierre Ricci 《European journal of plant pathology / European Foundation for Plant Pathology》1996,102(2):181-192
Elicitins are a family of proteins excreted byPhytophthora spp. They exhibit high sequence homology but large net charge differences. They induce necrosis in tobacco plants which then become resistant to the tobacco pathogenPhytophthora parasitica var.nicotianae. In stem-treated plants, resistance was not restricted to the site of elicitin application, but could be demonstrated by petiole inoculation at all levels on the stem. Resistance was already maximum after two days and lasted for at least two weeks. It was effective not only towardsP. p. var.nicotianae infection, but also against the unrelated pathogenSclerotinia sclerotiorum. In contrast to dichloroisonicotinic acid, an artificial inducer of systemic acquired resistance, which was increasingly effective with doses ranging from 0.25 to 5mole per plant, the basic elicitin cryptogein exhibited a threshold effect, inducing near total resistance and extensive leaf necrosis above 0.1 nmole per plant. Between 1 and 5 nmole, acidic elicitins (capsicein and parasiticein) protected tobacco plants with hardly any necrotic symptom. Elicitins exhibited similar effects in various tobacco cultivars andNicotiana species, although with quantitative differences, but induced neither necrosis nor protection in other SolanaceÆ (tomato, petunia and pepper). Among 24 additional species tested belonging to 18 botanical families, only some BrassicaceÆ, noticeably rape, exhibited symptoms in response to elicitins, in a cultivar-specific manner. Elicitins appear to be natural specific triggers for systemic acquired resistance and provide a tool for unraveling the mechanisms leading to its establishment.Abbreviations AR
acquired resistance
- HR
hypersensitive response
- INA
2,6-dichloroisonicotinic acid
- Ppn
Phytophthora parasitica var.nicotianae
- SAR
systemic acquired resistance 相似文献
3.
Alba Marina Cotes Philippe Lepoivre Jean Semal 《European journal of plant pathology / European Foundation for Plant Pathology》1996,102(5):497-506
An experimental protocol consisting in the colonisation of pregerminated bean seeds dressed withTrichoderma sp. was used in order to study the mechanisms correlated with the protective effect againstPythium splendens. Seed dressed with TH-11 (T. koningii) for 24 h presented a higher protective effect and a higher level of seed colonisation as compared to those dressed with TH-13 (T. longibranchiatum). The levels of seed coat colonisation by TH-11 and TH-13 was shown to be correlated with the carboxymethylcellulase activity, as measured in the seed coats retreived from germinating dressed bean seeds. The seed coat colonisation was also associated with an increased activities of endo-1,3--glucanase and endochitinase measured in seed extracts, and an inhibitory effect of seed extracts onPythium sporangia germination. Pretreatment of TH-13-dressed seeds with a commercial cellulase improved all parameters mentioned above, thus suggesting a role of cellulase activity in the colonisation process and the linked protective effect. The possible role of hydrolytic enzymes in the protective effects is discussed. 相似文献
4.
1. The performance of six commercial stocks of laying hens fed on a diet composed of home‐produced foodstuffs, not usually used for human consumption, was compared with that of birds fed on a conventional diet.
2. The experimental diet was calculated to be low in energy and methionine and high in fibre by conventional standards. Birds ate up to 12% more of this diet, but the calculated intakes of energy and methionine were less than those of the corresponding controls.
3. White stocks fed on the experimental diet produced seven eggs less per bird than controls while the production of brown stocks was essentially unaffected.
4. The gross efficiency of energy utilisation for egg production was better with the experimental diet. 相似文献
5.
Nicolas Rose Alain Abhervé-Guéguen Gérald Le Diguerher Eric Eveno Jean-Pierre Jolly Philippe Blanchard Aurélie Oger André Jestin François Madec 《Livestock Production Science》2005,95(3):177-186
The aim of this study was to determine the potential risk factors for PMWS at the individual pig level and assess the effect of the Pietrain paternal genetic background of the animals in a cohort study. The survey was set up in four PMWS-affected farms with 2 repetitions (batches) per farm. A representative sample of 60 pigs per batch, stratified according to the paternal genetic background (Pietrain: yes vs. no), was randomly selected after farrowing. The representative cohort was divided into 8 batches and the pigs were individually monitored from birth to slaughter. Survival analysis was used to determine the factors related to the time to PMWS. The litter-cluster effect was taken into account using the marginal Cox model (robust estimation of the covariance matrix) and the gamma shared frailty model which were compared.No protective effect of the Pietrain breed on the time to PMWS and the proportion of affected pigs in the offspring was found in this study. Piglets showing low circovirus type 2 (PCV2) titres at 7 weeks-old with no subsequent seroconversion and piglets from PCV2 negative sows were most likely to be affected by PMWS (HR=7.0 and 2.8, respectively). Active infection of the pregnant dams with parvovirus was related to an increased risk of PMWS in the offspring (HR=2.3). Neck injuries due to poorly performed injections in the dams were associated with an increased risk of PMWS with the marginal model (HR=2.1). Oxytocin injection (dams) during farrowing was protective against PMWS in the offspring (HR=0.6). 相似文献
6.
7.
8.
Raphaël Lagarde Nils Teichert Henri Grondin Thomas Hue Philippe Gaudin Dominique Ponton 《Ecology of Freshwater Fish》2020,29(1):63-73
This study investigates how age at first maturity of two tropical amphidromous species Sicyopterus lagocephalus (Pallas, 1770) and Cotylopus acutipinnis (Guichenot, 1863) varies in relation to their larval and juvenile life history. Reproductive stage was estimated based on histological observation of ovaries of more than 200 females of each species caught monthly over 1 year. The age of fish was estimated by interpreting the daily increments deposited on otoliths during the oceanic larval phase, and the juvenile phase in the river. The age at first maturity was approximately 9 months for S. lagocephalus and 7 months for C. acutipinnis, corresponding to approximately 70–130 and 90–130 days after they returned to freshwater respectively. For both species, the time spent in freshwater before maturity was significantly influenced by the duration of the pelagic larval stage at sea (PLD) and the season of return in freshwater. Individuals with a long PLD, or returning in freshwater during the warmer season, maturated faster once in freshwater. This reproductive advantage may minimise the risk of extirpation due to catastrophic events at each generation and thus probably benefits amphidromous species living in very unpredictable tropical rivers. 相似文献
9.
Influence of four soil maintenance practices on Collembola communities in a Mediterranean vineyard 总被引:1,自引:0,他引:1
Anglique Renaud Nicole Poinsot-Balaguer Jrme Cortet Jean Le Petit 《Pedobiologia》2004,48(5-6):623-630
We studied the influence of four soil maintenance practices on Collembola communities in the soil of a Mediterranean vineyard: (a) postemergence herbicide with glyphosate; (b) postemergence and pre-emergence herbicides with glyphosate, terbuthylazine, diuron and oryzalin; (c) natural flora and (d) tillage to a depth of 10–15 cm. Total Collembola abundance, species diversity and species richness significantly varied between the four practices. Notably, the practice using postemergence and pre-emergence herbicides had significantly lower values. Identification of Collembola at species level allowed an interspecies comparison and revealed significant differences for the most common species between the four practices, with each practice being characterized by a different set of species. None of the species were found to be significantly more abundant in the plots treated with postemergence and pre-emergence herbicides. 相似文献
10.
Severe hyperkalemia presenting with wide‐complex tachycardia in a puppy with acute kidney injury secondary to leptospirosis
下载免费PDF全文
![点击此处可从《Journal of Veterinary Emergency and Critical Care》网站下载免费的PDF全文](/ch/ext_images/free.gif)