全文获取类型
收费全文 | 202篇 |
免费 | 11篇 |
国内免费 | 4篇 |
专业分类
林业 | 33篇 |
农学 | 2篇 |
基础科学 | 1篇 |
19篇 | |
综合类 | 84篇 |
农作物 | 12篇 |
畜牧兽医 | 16篇 |
园艺 | 2篇 |
植物保护 | 48篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 1篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 10篇 |
2015年 | 2篇 |
2014年 | 6篇 |
2013年 | 7篇 |
2012年 | 13篇 |
2011年 | 13篇 |
2010年 | 18篇 |
2009年 | 21篇 |
2008年 | 17篇 |
2007年 | 20篇 |
2006年 | 14篇 |
2005年 | 7篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 8篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1989年 | 1篇 |
排序方式: 共有217条查询结果,搜索用时 15 毫秒
161.
When herbivores feed on insect-resistant transgenic plants, food consumption and utilization are probably affected. Quantifying
these parameters is of importance, because they may be associated with the performance of parasitoids, which are important
antagonists of herbivorous pests. In this study, relative consumption rate (RCR), relative growth rate (RGR), approximate
digestibility (AD), efficiency of conversion of digested food into body matter (ECD) and efficiency of conversion of ingested
food into body matter (ECI) ofChilo partellus Swinhoe larvae (Lepidoptera: Crambidae) exposed to different concentrations of transgenic insect-resistantBacillus thuringiensis-corn (Bt-corn) tissue suspension, were investigated under laboratory conditions. For the control groups, different concentrations
of control corn tissue suspension were used. In order to determine whether Bt effects were influenced by larval age, 4- and
17-day-old larvae were used. At all concentrations and for larvae of both ages, RGR, RCR, ECD and ECI values in the control
were significantly higher than in the Bt group. Moreover, there was a gradual decrease in RCR, RGR and ECI values when Bt
concentrations were increased. However, AD values at the lowest Bt concentration were significantly higher than in the control,
whereas no significant differences between both groups could be detected at higher concentrations. In conclusion, the experiments
showed that nutritional indices of herbivores exposed to transgenic insect-resistant plants could be quantified to determine
the effects of these plants on target or non-target organisms. This could be one component in future evaluation of the effect
of transgenic insect-resistant plants on the second and third trophic level.
http://www.phytoparasitica.org posting Aug. 28, 2005. 相似文献
162.
163.
The pale-winged gray moth, Iridopsis ephyraria (Walker), a native geometrid moth species found across eastern North America, has recently caused severe defoliation of eastern hemlock trees, Tsuga canadensis (L.) Carrière, in south-central Nova Scotia, Canada. Field studies were carried out to develop sampling techniques that could be used to predict subsequent defoliation of mature hemlocks, which are too large to sample by conventional methods. Densities of newly emerged, first-instar larvae, estimated by sticky tape traps, explained 77% of the subsequent current-year shoot defoliation by I. ephyraria. Egg densities from foam oviposition traps and mid-instar larval densities from beating sheets were weakly and usually non-significantly related to defoliation. Therefore, foam oviposition traps could be used to qualitatively estimate egg densities of I. ephyraria, but first-instar larvae must be sampled with sticky tape if accurate predictions of hemlock defoliation are desired. 相似文献
164.
This study investigated the effects of different GM maize crops on the abundances of rove beetles. It also investigated competition between rove beetles and other epigeic arthropod predatory groups (ground beetles and spiders). Altogether a total of 5926 rove beetle individuals belonging to 25 species were collected. Whilst the average number of rove beetle individuals per replicate per sampling date varied and, moreover, decreased each year, there were no observed differences in rove beetle abundance when compared between isogenic and GM maize plots within the study period. Furthermore, no clear trends on positive correlations between weed coverage and rove beetle abundances were detected. Altogether a total number of 76,070 ground beetle individuals and 11,126 spiders (including all Araneae) were collected with pitfall traps. Analyses revealed a strong negative relationship between rove beetles and the other two groups in each treatment and year. According to the results the effect of interspecific competition on rove beetle abundance in GM maize is much higher than the effects of treatments including both Bt toxins and extra glyphosate applications. 相似文献
165.
通过对内蒙古大兴安岭汗马自然保护区蝶类的调查研究,发现中国红眼蝶属(Erebia Dalman)一新记录种:珠红眼蝶(Erebia embla(Thunberg,1791))。对该种的外部形态和外生殖器特征进行了描述,并给出了成虫、外生殖器图片和分布范围。 相似文献
166.
Patterns of local and regional dominance within species assemblages can be used to infer the legacy of disturbance in managed systems. Specifically, highly disturbed communities are expected to share the same dominant species across environmental gradients, while recovery from disturbance should be correlated with a differentiation among the dominant suite of species among sites. We tested this hypothesis using moth communities sampled from 20 forest stands within three watersheds managed for complete timber harvest 60 years prior. Specifically, we (1) compared the species-abundance distributions for all moths sampled from the forests, (2) used ordination and indicator species analysis to assess whether the same taxa were most dominant within each forest stand, and (3) tested whether dominant taxa were disproportionately niche generalists compared to all species sampled from the larger species pools within each watershed. With only a single significant exception, moth communities within the forest stands shared the log-normal species-abundance distribution. Ordination suggested some evidence of divergence in species dominance among individual forest stands, but differences were not based on watershed identity or spatial proximity. Few dominant species appeared to display a high level of fidelity to any particular stand or watershed in the region. Finally, dominant taxa were not disproportionately niche generalists, but this result was largely driven by the absence of niche specialists from the entire forested landscape. Thus, we suggest that the moth communities from this managed forest system still bear a clear legacy of timber management more than 60 years post-harvest. Shifts in dominant moth taxa among forest stands may be largely idiosyncratic in nature. 相似文献
167.
168.
对黄土高原南部的渭北沟壑区退耕还林还草后的昆虫区系进行了调查研究。结果表明,该试区有鳞翅目森林昆虫31科174属253种,其中蛾类26科137属197种,蝴蝶类5科37属56种;古北界、古北-东洋跨界种类是该试区鳞翅目昆虫区系的主要组成类群;试验区鳞翅目昆虫区系组分具有过渡性、多样性特征,并且这些特征在一定程度上受人工植被类型的影响。 相似文献
169.
170.