全文获取类型
收费全文 | 164篇 |
免费 | 12篇 |
专业分类
林业 | 26篇 |
农学 | 6篇 |
42篇 | |
综合类 | 9篇 |
农作物 | 19篇 |
水产渔业 | 20篇 |
畜牧兽医 | 17篇 |
园艺 | 3篇 |
植物保护 | 34篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 12篇 |
2017年 | 15篇 |
2016年 | 9篇 |
2015年 | 9篇 |
2014年 | 11篇 |
2013年 | 14篇 |
2012年 | 7篇 |
2011年 | 15篇 |
2010年 | 10篇 |
2009年 | 9篇 |
2008年 | 13篇 |
2007年 | 8篇 |
2006年 | 2篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 5篇 |
2001年 | 1篇 |
1995年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有176条查询结果,搜索用时 15 毫秒
21.
22.
Saridomichelakis MN Koutinas AF Olivry T Dunston SM Farmaki R Koutinas CK Petanides T 《Veterinary dermatology》2007,18(4):227-233
In canine leishmaniosis, the parasitic density of the skin may be important for the infection of sandflies, and increased accumulation of inflammatory cells infected with Leishmania is believed to occur in dermal areas subjected to mechanical trauma. Parasite density and inflammatory responses in the upper and lower dermis of three body sites: flank (control site), dorsal muzzle (sandfly feeding site), and footpads (mechanical stress sites) were thus investigated in 15 dogs with symptomatic leishmaniosis. Parasite density did not differ between the control and tested sites or between the upper and lower dermis, apart from the footpads where it was higher in the upper dermis, and there was no correlation with severity of the macroscopic lesions or inflammatory infiltrate, except for the lower footpad dermis. No selective accumulation of the parasite in the muzzle that would favour its transmission to sandflies occurred, and the mechanical stress imposed on the footpads was not associated with increased parasitic density, or with inflammatory infiltrate. 相似文献
23.
BACKGROUND: Papaver rhoeas (L.) has evolved resistance to tribenuron in winter wheat fields in northern Greece owing to multiple Pro197 substitutions. Therefore, the cross‐resistance pattern to other sulfonylurea and non‐sulfonylurea ALS‐inhibiting herbicides of the tribenuron resistant (R) and susceptible (S) corn poppy populations was studied by using whole‐plant trials and in vitro ALS catalytic activity assays. RESULTS: The whole‐plant trials revealed that tribenuron R populations were also cross‐resistant to sulfonylureas mesosulfuron + iodosulfuron, chlorsulfuron and triasulfuron. The whole‐plant resistance factors (RFs) calculated for pyrithiobac, imazamox and florasulam ranged from 12.4 to > 88, from 1.5 to 28.3 and from 5.6 to 25.4, respectively, and were lower than the respective tribenuron RF values (137 to > 2400). The ALS activity assay showed higher resistance of the ALS enzyme to sulfonylurea herbicides (tribenuron > chlorsulfuron) and lower resistance to non‐sulfonylurea ALS‐inhibiting herbicides (pyrithiobac > florasulam ≈ imazamox). CONCLUSION: These findings indicate that Pro197 substitution by Ala, Ser, Arg or Thr in corn poppy results in a less sensitive ALS enzyme to sulfonylurea herbicides than to other ALS‐inhibiting herbicides. The continued use of sulfonylurea herbicides led to cross‐resistance to all ALS‐inhibiting herbicides, making their use impossible in corn poppy resistance management programmes. Copyright © 2011 Society of Chemical Industry 相似文献
24.
25.
26.
Christos G. Athanassiou Nickolas G. Kavallieratos Giovanni Benelli Raul Narciso C. Guedes 《Journal of pest science》2018,91(3):1073-1080
Multiple matings occur in many species of stored-grain insect pests, such as the rice weevil Sitophilus oryzae (L.), with both female and male mating more than once and with more than one partner. Multiple female mating in S. oryzae increased lifetime fecundity by extending the period of time progeny were produced, but consequences of multiple male mating in S. oryzae were not yet studied although it is likely to increase male fitness by increasing offspring production. Here, the effects of polygynous mating on male mating behavior, success, and fitness were assessed in two strains of S. oryzae, one adapted to barley and another to wheat. Two insect strains were considered because they may differ in response depending on the host grain, which present distinct nutritional value to the insects. Mating by pairs formed between the two strains did not impact mating success, but wheat-adapted females exhibited longer mating duration, which was positively correlated with progeny production. Wheat-adapted males exhibited higher fertility than barley-adapted males. When male multiple matings were considered in successive polygynous matings, late matings led to lower non-cumulative values of progeny production, but higher cumulative performance, and wheat-adapted S. oryzae always performed better. Thus, male fitness and grain losses in wheat are higher than in barley, even when S. oryzae was adapted to the latter. 相似文献
27.
28.
Comparison of passive and active canopy sensors for the estimation of vine biomass production 总被引:1,自引:0,他引:1
Stamatis Stamatiadis Dimitris Taskos Eleftheria Tsadila Calliopi Christofides Christos Tsadilas James S. Schepers 《Precision Agriculture》2010,11(3):306-315
Recent advances in optical designs and electronic circuits have allowed the transition from passive to active proximal sensors.
Instead of relying on the reflectance of natural sunlight, the active sensors measure the reflectance of modulated light from
the crop and so they can operate under all lighting conditions. This study compared the potential of active and passive canopy
sensors for predicting biomass production in 25–32 randomly selected positions of a Merlot vineyard. Both sensors provided
estimates of the normalized difference vegetation index (NDVI) from a nadir view of the canopy at veraison that were good
predictors of pruning weight. Although the red NDVI of the passive sensors explained more of the variation in biomass (R
2 = 0.82), its relationship to pruning weight was nonlinear and was best described by a quadratic regression (NDVI = 0.55 + 0.50 wt−0.21 wt2). The theoretically greater linearity of the amber NDVI-biomass relationship could not be verified under conditions of high
biomass. The linear correlation to stable isotope content in leaves (13C and 15N) provided evidence that canopy reflectance detected plant stresses as a result of water shortage and limited fertilizer
N uptake. Thus, the canopy reflectance data provided by these mobile sensors can be used to improve site-specific management
practices of vineyards. 相似文献
29.
A tale of two seas: a meta‐analysis of crustacean stocks in the NE Atlantic and the Mediterranean Sea
下载免费PDF全文
![点击此处可从《Fish and Fisheries》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Meta‐analysis of marine biological resources can elucidate general trends and patterns to inform scientists and improve management. Crustacean stocks are indispensable for European and global fisheries; however, studies of their aggregate development have been rare and confined to smaller spatial and temporal scales compared to fish stocks. Here, we study the aggregate development of 63 NE Atlantic and Mediterranean crustacean stocks of six species (Nephrops norvegicus, Pandalus borealis, Parapenaeus longirostris, Aristeus antennatus, Aristaeomorpha foliacea and Squilla mantis) in 1990–2013 using biomass index data from official stock assessments. We implemented a dynamic factor analysis (DFA) to identify common underlying trends in biomass indices and investigate the correlation with the North Atlantic Oscillation (NAO) index. The analysis revealed increasing and decreasing trends in the northern and southern NE Atlantic, respectively, and stable or slowly increasing trends in the Mediterranean, which were not related to NAO. A separate meta‐analysis of the fishing mortality (F) and biomass (B) of 39 analytically assessed crustacean stocks was also carried out to explore their development relative to MSY. NE Atlantic crustacean stocks have been exploited on average close to FMSY and remained well above BMSY in 1995–2013, while Mediterranean stocks have been exploited 2–4 times above FMSY in 2002–2012. Aggregate trends of European crustacean stocks are somewhat opposite to trends of fish stocks, suggesting possible cascading effects. This study highlights the two‐speed fisheries management performance in the northern and southern European seas, despite most stocks being managed in the context of the European Union's Common Fisheries Policy. 相似文献
30.