全文获取类型
收费全文 | 671篇 |
免费 | 54篇 |
国内免费 | 30篇 |
专业分类
755篇 |
出版年
2024年 | 3篇 |
2023年 | 12篇 |
2022年 | 15篇 |
2021年 | 30篇 |
2020年 | 17篇 |
2019年 | 25篇 |
2018年 | 20篇 |
2017年 | 20篇 |
2016年 | 18篇 |
2015年 | 19篇 |
2014年 | 39篇 |
2013年 | 43篇 |
2012年 | 16篇 |
2011年 | 26篇 |
2010年 | 23篇 |
2009年 | 23篇 |
2008年 | 28篇 |
2007年 | 40篇 |
2006年 | 25篇 |
2005年 | 35篇 |
2004年 | 20篇 |
2003年 | 17篇 |
2002年 | 19篇 |
2001年 | 16篇 |
2000年 | 14篇 |
1999年 | 12篇 |
1998年 | 15篇 |
1997年 | 16篇 |
1996年 | 11篇 |
1995年 | 4篇 |
1994年 | 11篇 |
1993年 | 9篇 |
1992年 | 6篇 |
1991年 | 14篇 |
1990年 | 12篇 |
1989年 | 11篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有755条查询结果,搜索用时 15 毫秒
731.
732.
Christoph Randler 《European Journal of Wildlife Research》2006,52(4):265-270
Animals frequently interrupt their activity to look up and to scan their surrounding environment for potential predators (vigilance).
As vigilance and other activities are often mutually exclusive, such behaviours are at the expense of feeding, sleeping or
preening. Authors of many wildlife disturbance studies found that people with free-running dogs provoked the most pronounced
disturbances (e.g. greater flushing distances and more birds affected). However, dogs on leash may also negatively affect
wild animals, and barking dogs may lead to an increase in vigilance. In this study, I tested this hypothesis in coots (Fulica atra) using three different playback procedures: (1) dog barks, (2) conspecific coot alarm calls and (3) chaffinch song. The trials
were conducted in spring and autumn 2005 at three study sites in southwestern Germany. During the dog playbacks, vigilance
increased significantly from 17 to 28%. This increase in vigilance is comparable to the presence of a natural predator. As
expected, vigilance also increased significantly during conspecific coot alarm calls but not during playbacks of the chaffinch
song control. Two main findings result from the study: (1) coots respond to acoustic traits of dogs and may be able to acoustically
recognise this predator and (2) this increase in vigilance might have implications for conservation, especially when considering
buffer zones around sensitive areas. 相似文献
733.
J. H. van Hateren H. P. Snippe 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2006,192(2):187-197
Phototransduction in primate cones is compared with phototransduction in blowfly photoreceptor cells. Phototransduction in
the two cell types utilizes not only different molecular mechanisms, but also different signal processing steps, producing
range compression, contrast constancy, and an intensity-dependent integration time. The dominant processing step in the primate
cone is a strongly compressive nonlinearity due to cGMP hydrolysis by phosphodiesterase. In the blowfly photoreceptor a considerable
part of the range compression is performed by the nonlinear membrane of the cell. Despite these differences, both photoreceptor
cell types are similarly effective in compressing the wide range of naturally occurring intensities, and in converting intensity
variations into contrast variations. A direct comparison of the responses to a natural time series of intensities, simulated
in the cone and measured in the blowfly photoreceptor, shows that the responses are quite similar. 相似文献
734.
Susan L. Makris Howard M. Solomon Ruth Clark Kohei Shiota Stephane Barbellion Jochen Buschmann Makoto Ema Michio Fujiwara Konstanze Grote Keith P. Hazelden Kok Wah Hew Masao Horimoto Yojiro Ooshima Meg Parkinson L. David Wise 《Birth defects research. Part B, Developmental and reproductive toxicology》2009,86(4):227-327
735.
ABSTRACT. 1. Studies involving experiments with olfactometers and field experiments have shown that the release of sex-pheromone by females of Yponomeuta spp. is stimulated by the presence of host plants.
2. While in Y.evonymellus L. less females emitted pheromone in the absence of host plants, in Y.padellus L. the initiation of pheromone release was delayed.
3. Females of Y.evonymellus, Y.cagnagellus Hüb., Y.padellus and Y.plumbellus D. & S. all preferred a place with host-plant odour to one with non-host odours for sex-pheromone release.
4. Male preference for host-plant odour was demonstrated in the laboratory only for Y.cagnagellus.
5. Trap catches in the field indicated a reinforcement of female attractiveness by host-plant stimuli. 相似文献
2. While in Y.evonymellus L. less females emitted pheromone in the absence of host plants, in Y.padellus L. the initiation of pheromone release was delayed.
3. Females of Y.evonymellus, Y.cagnagellus Hüb., Y.padellus and Y.plumbellus D. & S. all preferred a place with host-plant odour to one with non-host odours for sex-pheromone release.
4. Male preference for host-plant odour was demonstrated in the laboratory only for Y.cagnagellus.
5. Trap catches in the field indicated a reinforcement of female attractiveness by host-plant stimuli. 相似文献
736.
Peter Bremen Iris Poganiatz Mark von Campenhausen Hermann Wagner 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2007,193(1):99-112
Standard electrophysiology and virtual auditory stimuli were used to investigate the influence of interaural time difference
on the azimuthal tuning of neurons in the core and the lateral shell of the central nucleus of the inferior colliculus of
the barn owl. The responses of the neurons to virtual azimuthal stimuli depended in a periodic way on azimuth. Fixation of
the interaural time difference, while leaving all other spatial cues unchanged, caused a loss of periodicity and a broadening
of azimuthal tuning. This effect was studied in more detail in neurons of the core. The azimuthal range tested and the frequency
selectivity of the neurons were additional parameters influencing the changes induced by fixating the interaural time difference.
The addition of an interaural time difference to the virtual stimuli resulted in a shift of the tuning curves that correlated
with the interaural time difference added. In this condition, tuning strength did not change. These results suggest that interaural
time difference is an important determinant of azimuthal tuning in all neurons of the core and lateral shell of the central
nucleus of the inferior colliculus, and is the only determinant in many of the neurons from the core. 相似文献
737.
Male Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) used their aristae to repeatedly tap the female, usually on her aristae, during the second stage of head rocking courtship. The male's antennae moved in an apparently exploratory manner earlier in head rocking. Reduced rates of copulation followed removal of male and female aristae, supporting the idea that tapping with the aristae is an important part of medfly courtship. 相似文献
738.
739.
Abstract. Effects of form, colour, and pheromone of twospotted spider mite, Tetranychus urticae (Koch), quiescent deutonymphs on adult male guarding behaviour were tested independently and in combination using no-choice and sequential-presentation bioassays. Significantly more males approached yellow stimuli sources than non-yellow sources in all bioassays, suggesting that males orient visually to yellow carotenoid pigments of quiescent deutonymphs. The form and extract (pheromone) of quiescent deutonymphs did not increase male approach frequency. All three cues elicited male arrestment; contrasts of 2 × 3 factorial bioassay data showed that male tactile and/or visual perception of form increased arrestment frequency more than did contact chemoperception of extract, while extract perception caused more arrestments than did visual perception of colour. All three cues prolonged arrestment duration and increased frequency of intermale conflicts near stimuli sources, but form had greater impact than did other cues on the numbers of conflicts observed during coguarding incidents. Significant interactions among stimuli were observed, indicating that presence of multiple stimuli had a synergistic effect on the duration of male response. Males approached and were arrested by all three stimuli combined as often as by quiescent deutonymphs, but arrestments caused by quiescent deutonymphs were longer than those elicited by artificial stimuli. This difference suggests that either additional cues or differences in pheromone release rates are involved in eliciting and prolonging male T. urticae guarding behaviour. 相似文献
740.
DANIEL J. HEFFERNAN WILLIAM F. ANDELT JOHN A. SHIVIK 《The Journal of wildlife management》2007,71(2):587-593
ABSTRACT Because coyotes (Canis latrans) show an aversion to novel objects, we examined the effects of the presence and removal of repellent and attractive stimuli on coyote behavior. We found a greater proportion of captive coyotes investigated 10-cm-tall cones (0.95) compared to 90-cm-tall cones (0.68) and control sites (0.81), and spent longer periods (P < 0.001 in all instances) investigating small cones (x̄ = 465 sec), compared to large cones (x̄ = 212 sec) and control sites (x̄ = 45 sec). However, investigation times at sites following removal of large cones were 1.6 and 2.3 times greater than investigation times at sites following removal of small cones and the control, respectively. Results from pen studies were supported by a field study. Wild coyotes in south Texas visited 43% of small cones but did not visit large cones. Following removal of cones, visits to small cone stations decreased to 29%, whereas coyotes visited 43% of large cone stations. Thus, we observed a direct relationship between aversion toward large novel objects and subsequent attraction to sites following their removal among both captive and wild coyotes. Based upon our results, we suggest that placing large novel objects over traps that are set and removing such objects after a few days, with the subsequent addition of an olfactory attractant, may increase exploratory behavior and capture of coyotes. 相似文献