全文获取类型
收费全文 | 350篇 |
免费 | 11篇 |
国内免费 | 5篇 |
出版年
2022年 | 4篇 |
2021年 | 6篇 |
2020年 | 2篇 |
2019年 | 7篇 |
2018年 | 9篇 |
2017年 | 3篇 |
2016年 | 9篇 |
2015年 | 7篇 |
2014年 | 22篇 |
2013年 | 10篇 |
2012年 | 7篇 |
2011年 | 7篇 |
2010年 | 3篇 |
2009年 | 23篇 |
2008年 | 25篇 |
2007年 | 18篇 |
2006年 | 21篇 |
2005年 | 17篇 |
2004年 | 17篇 |
2003年 | 11篇 |
2002年 | 16篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 8篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 9篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1982年 | 3篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1970年 | 4篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1964年 | 1篇 |
1963年 | 2篇 |
排序方式: 共有366条查询结果,搜索用时 15 毫秒
71.
Egg discrimination in hosts of the common cuckoo Cuculus canorus is frequently studied by experimental parasitism, using model cuckoo eggs. We compared egg rejection behaviour of the great
reed warbler Acrocephalus arundinaceus to either model cuckoo eggs made of plastic or painted real host eggs. We simultaneously parasitised host nests by two different
egg types to simulate cuckoo parasitism. A previous study revealed very similar, ca. 70%, rejection rates against both of
these egg types (beige or bluish background colour maculated with dark brown) when they were used for single parasitism. In
the present study we showed 96% average rejection rates against these egg types when they were applied in multiple experimental
parasitism, causing a more predictable output for rejection behaviour. Hard plastic eggs and painted real eggs were rejected
at similar frequencies, and videotaping revealed that model egg rejection caused extra work for great reed warblers. We revealed
a new type of rejection behaviour, when hosts tried to eject hard-shelled model cuckoo eggs: Hosts made little holes in the
middle part of these plastic eggs by pecking them several times before ejection, as if seeking the possibility to pierce and
hold these eggs in their bills. Painted real eggs were rejected by actually puncturing the eggshell and holding them in the
bill during ejection. No instances of grasp ejection were recorded during filming. Most experimental eggs of either type were
ejected within 1 day after the introduction of the eggs, indicating that hosts made their rejection decisions quickly. Our
observations suggest the lack of plasticity in the mode and timing of ejection behaviour towards experimental cuckoo eggs
of different types in great reed warblers. 相似文献
72.
A.M.A. Mahmoud E.J. De Luna-SantillanaX. Guo F. Reyes-VillanuevaMario A. Rodríguez-Pérez 《Journal of Asia》2012,15(1):63-68
Cotesia flavipes is an important gregarious larval endoparasitoid of several crambid stem borers, including Diatraea saccharalis. The suitability of two crambid species, Eoreuma loftini and D. saccharalis, pests of sugarcane and rice in Texas, for C. flavipes development was tested. The effect of parasitization by C. flavipes on encapsulation response was assessed in vivo in both D. saccharalis and E. loftini. The results indicated that the parasitoid developed and emerged successfully in D. saccharalis larvae. Although E. loftini larvae were readily parasitized by C. flavipes parasitoids, no wasp larvae hatched from the eggs in this host because eggs were encapsulated by the host's hemocytes. The developmental fate of the E. loftini larvae with encapsulated parasitoids was variable. Most died as abnormal fifth instars or as post-wandering prepupae, while a few developed normally to the pupal stage. In vivo experiments, there was a significant reduction in the percent of beads encapsulated in parasitized larvae in both hosts. However, the percent of beads showing melanization decreased significantly in parasitized D. saccharalis larvae but did not differ significantly in parasitized or unparasitized E. loftini larvae. Our results showed that D. saccharalis is a suitable host for C. flavipes whereas E. loftini is an unsuitable host. This study indicated that lepidopteran stem borers that are taxonomically, behaviorally, and ecologically very similar can differ in their ability to encapsulate a parasitoid species. 相似文献
73.
Zi-Hua Zhao Cang Hui Fang Ouyang Jun-He Liu Xiao-Qing Guan Da-Han He Feng Ge 《Basic and Applied Ecology》2013,14(6):472-479
The agricultural intensification and the subsequent habitat changes in agroecosystem can strongly affect biological control services. We here examine the influence of inter-annual landscape change in wheat field area on interactions of cereal aphids and their natural enemies, as well as the efficacy of biological control using data collected from a 4-year experiment in Northwest China. Two hypotheses were tested. (i) Population densities decline following an inter-annual expansion of wheat crop proportion cover due to dilution and crowding effects. (ii) Species that are specialists or at higher trophic levels are more sensitive to bottom-up disturbance by inter-annual change in percent cover of wheat crop. Results showed the population densities of one cereal aphid (Macrosiphum avenae), one parasitic wasp (Aphidius avenae), two specialist predators (ladybirds: Hippodamia variegata and H. tredecimpunctata) and one hyperparasitic wasp (Pachyneuron aphidis) declined following the expansion of wheat crop areas, supporting the predictions of inter-annual dilution and crowding effects. In contrast, the populations of one cereal aphid (Schizaphis graminum), one parasitic wasp (A. gifuensis), two generalist predators (spiders: Pardosa astrigera; carabid beetles: Chlaenius pallipes), and two hyperparasitic wasps (Asaphes suspensus, and Alloxysta sp.) did not respond to inter-annual landscape change. The two hypotheses were partially supported but with noticeable exceptions, and the bio-control efficiency declined with the increase of the proportion cover of wheat field in agricultural landscape. Overall, different responses of cereal aphids and their natural enemies make it difficult but still possible to optimize inter-annual landscape change for enhancing the parasitism rate and predator-prey ratio. 相似文献
74.
Tomo-o Royama 《Population Ecology》2001,43(2):157-178
A theory and practical method are developed to evaluate insect survivorship as a continuous process in time and the effects
of major factors that determine it, with a view to providing solutions to certain problems in survivorship studies. There
are two ways of assessing mortality rates: nominal and marginal. A nominal rate is based on the number tallied in terms of the immediate cause of death; it depends on the method of observation
employed and can be inconsistent between studies. A marginal rate is free of such inconsistency. The marginal rate attributable
to the union of parasitism and disease is evaluated by frequent sampling in the field and rearing of each batch of samples
in the laboratory for a short period of time. Comparing this rate with the field mortality rate, directly evaluated by sampling,
determines marginal predation rate. The marginal parasitism and disease rates cannot be determined by observation. A computational
method is developed to evaluate their approximate values. A step-by-step procedure of numerical calculations with data is
provided in an appendix. The accuracy of estimating mortality depends on the frequency of sampling in the field and that of
inspecting dead individuals in rearing. How frequently sampling and inspection should be conducted is discussed. The method
of assessing parasitism developed here has a great advantage over the conventional method based on dissecting the samples,
or rearing them through, that often results in a serious underestimation. Also discussed is the relative importance of mortality
factors from the pest control point of view, and the concept of “joint contribution” is introduced. Other practical considerations
include transportation of samples; rearing conditions; and how to deal with the “dead-in-the-field” in the samples, the “rearing-death
syndrome,” and the “virtually dead” individuals.
Received: August 25, 2000 / Accepted: May 17, 2001 相似文献
75.
Tobias Policha David A. Grimaldi Rocío Manobanda Adrian Troya Ashley Ludden Bryn T. M. Dentinger Bitty A. Roy 《Ecological Entomology》2019,44(4):457-470
1. Dracula orchids mimic mushrooms in appearance and scent, and are pollinated by mushroom flies. This study examined the guilds of insect visitors to Dracula species and to co‐occurring mushrooms in an Ecuadorean cloud forest. Significant visitor overlap was documented (mostly in the genera Zygothrica and Hirtodrosophila; Drosophilidae). To test the brood‐site mimicry hypothesis, behavioural observations were also performed and rearing success was examined. 2. Many fly species that visit Dracula are also found on mushrooms. Furthermore, the presence of pollinia enabled us to document the fact that particular individuals visiting mushrooms also visit Dracula. Roughly two‐thirds of the visitors to these unusual flowers are fungal‐associated, and the rest appear to be Dracula specialists. 3. A variety of behaviours common on both host groups were observed, including courtship semaphoring, feeding, sheltering, defending territory, and mating. Given this suite of shared reproductive behaviour, it was hypothesised that flies may also oviposit in both substrates. Flies were reared from mushrooms, Dracula spp., and other flowers (controls) to determine which substrate led to the highest fitness for the flies. Very few flies emerged from the Dracula flowers and there was no species overlap between the emergent insects and the known pollinators. 4. Despite the fact that there is evidence for brood‐site mimicry, the Dracula situation is complex. All the flies could derive many of the same fitness benefits from the flowers as they do from mushrooms (shelter, food, mating), but they are clearly not gaining the same fitness benefit, in terms of progeny, on flowers compared with mushrooms. 相似文献
76.
《Biological Control》2013,67(3):166-172
Estimates of the dispersal range of a recently introduced biocontrol agent in its new environment are vital to understanding its relative searching capacity, and to foresee the maximum area that could be covered in a release event. In New Zealand, the solitary endoparasitoid Cotesia urabae Austin and Allen (Hymenoptera: Braconidae) was first released in January 2011 as a biological control agent for the gum leaf skeletoniser, Uraba lugens Walker (Lepidoptera: Nolidae). The objective of this study was to utilize an experimental approach to quantify the dispersal behavior of one generation of C. urabae. In our experiment, which used sentinel larvae as target hosts, parasitoids dispersed up to 20 m away from the release point but parasitism was highest within 5 m of the release site. A high level of parasitism was observed at the release tree (87.6%) which suggests that most of the females released may have stayed there. According to the dispersal model developed from the data collected, Cotesia would be able to disperse up to 53 m in one release event. In addition, significant differences were found between the different directions tested for dispersal, showing a clear downwind effect on dispersal suggesting that wind has a direct effect on the dispersal behavior of C. urabae in the field. 相似文献
77.
《Archives of animal nutrition》2013,67(2):185-194
The aim of this investigation was to contribute to the problem of overdosing vitamin E. A total of 80 laying hens, divided into 5 groups, were fed diets supplemented with 0; 100, 1000, 10 000 and 20 000 mg/kg vitamin E over a period of 20 weeks within two brooding tests. Laying performance and hatching parameters were registered. All vitamin E doses did not significantly influence health and performances of hens. Vitamin E content of eggs increased from 1 to 4, 21, 46 and 51 mg per egg with vitamin E supplementation. High doses decreased oxidative stability of abdominal fat, vitamin A concentration of liver and egg yolk colour. In both tests vitamin E supplements of 10 000 and 20 000 mg/kg feed resulted in a decrease of living hatched chicken, which demonstrated an adverse effect. Further studies seem to be necessary to explain the effect. 相似文献
78.
This study reconstructs early stages of Rozella allomycis endoparasitic infection of its host, Allomyces macrogynus. Young thalli of A. macrogynus were inoculated with suspensions of R. allomycis zoospores and allowed to develop for 120 h. Infected thalli at intervals were fixed for electron microscopy and observed. Zoospores were attracted to host thalli, encysted on their surfaces, and penetrated their walls with an infection tube. The parasite cyst discharged its protoplast through an infection tube, which invaginated the host plasma membrane. The host plasma membrane then surrounded the parasite protoplast and formed a compartment confining it inside host cytoplasm. The earliest host-parasite interface within host cytoplasm consisted of two membranes, the outer layer the host plasma membrane and the inner layer the parasite plasma membrane. At first a wide space separated the two membranes and no material was observed within this space. Later, as the endoparasite thallus expanded within the compartment, the two membranes became closely appressed. As the endoparasite thallus continued to enlarge, the interface developed into three membrane layers. Thus, host plasma membrane surrounded the parasite protoplast initially without the parasite having to pierce the host plasma membrane for entry. Significantly, host-derived membrane was at the interface throughout development. 相似文献
79.
80.
Summary
Phytomyza ilicicola is a specialist herbivore, the larvae of which mine, and the adults of which feed and oviposit on the developing leaves of American Holly, Ilex opaca. Adult Phytomyza have been shown to discriminate among host plants on the basis of several host and habitat factors. Such discrimination may explain, in part, the observed density variation of larval Phytomyza among individual trees and between forest and suburban habitats. In order for discrimination to influence density, adult Phytomyza must be sufficiently vagile to move among habitats and to encounter many hosts. We experimentally monitored the movement of adults to ask if this were so. In addition we asked whether inter-host movements were altered by resource concentration, and whether vagility offered an escape from parasitism. To answer these questions, three isolated holly trees to serve as colonization sources were selected in early spring, prior to adult emergence. Potted target trees were then placed singly and in groups of four at 3 compass directions around and at 3 different distances (10, 25, and 50 m) from each of the source trees. Six weeks after exposure to adult Phytomyza, the number of feeding punctures and first instar larvae were counted. Clones were then overwintered in cold frames and in early spring, just prior to adult emergence, all pupae were examined for parasitism by the dominant parasitoid Opius striatriventris. Feeding and parasitism were similar at all 3 distances from the source trees, indicating that Opius was at least as vagile as Phytomyza. However, first instar larvae decreased with distance. There was no evidence that resource concentration affected adult movement. Our results suggest that Phytomyza are sufficiently vagile to choose among hosts within and between habitats. However, movement does not translate into equally high oviposition at all distances from a source, nor does it provide an escape from parasitism by Opius. 相似文献