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1.
Matthias Kirsch Mustafa B. A. Djamgoz Hans-Joachim Wagner 《Cell and tissue research》1990,260(1):123-130
Summary A negative feedback interaction between luminosity type horizonatal cells (HCs) and green-sensitive cones generates the long-wavelength-sensitive depolarizing response in biphasic chromaticity type HCs. This interaction is suppressed in the dark and is potentiated by light adaptation of the retina. HCs are morphologically plastic; during light adaptation, their dendritic terminals within cone pedicles extend, giving rise to spinules. This paper examines whether there is a quantitative correlation between the time course of light-dependent formation of the spinules and enhancement of the feedback interaction. The strength of the feedback interaction in isolated retinac of the roach was determined as the neutral wavelength at which reversal of spectral response polarity occurred in biphasic HCs. A good correlation was found between the neutral wavelength and the spinule/ribbon ratios of retinae. Biphasic HCs were intracellularly stained with horseradish peroxidase and the correlative ultrastructure of the contacted pedicles was examined. Neutral wavelength was found to be correlated with the spinule number, weighted according to the number of synaptic contacts mediating feed-forward transmission. The latter was estimated from the total number of labelled Cb/H2 HC processes (central and lateral) at synaptic triads. A model in which spinules mediate the negative feedback interaction of HCs in the retina of cyprinid fish is presented. 相似文献
2.
3.
The characteristics of a number of filamentous fungal cultures were obtained from two previously published numerical taxonomic studies on Penicillium and Phoma. The coding strategies for some of the physiological and morphological properties employed in the original studies were re-examined and the data was re-coded by combining sets of characters into single ordered multistate characters. The different coding procedures were compared by generating average linkage (UPGMA) dendrograms which were in turn compared by calculating correlation coefficients between the final similarity matrices implied by these dendrograms. The character conversions had no significant effect on the final outcome of the clustering. 相似文献
4.
Hiroyuki Uno Yumiko Ohno Tsuneo Yamada Kensaku Miyamoto 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1991,169(2):231-239
Summary The responses of neurons in field L in the auditory neostriatum of the mynah bird, Gracula religiosa, were recorded during presentation of intact or manipulated mimic voices. A typical mimic voice konnichiwa elicited responses in most of the neurons. Neurons in the input layer (L2) of field L showed many peaks on peristimulus time histograms while those in other layers (L1 and L3) exhibited only one or two peaks. Several neurons in L1 and L3 responded only to the affricative consonant /t/ in the intact mimic voices. They did not respond to the affricative consonant in the isolated segment or to the one in the playbacked voice in reverse. Forty-five percent of the neurons (33/ 73) decreased in firing rates at the affricative consonant in the isolated segment compared with in the intact voice. Some of these neurons, in which neither the affricative consonant in the isolated segment nor bursts of noise alone elicited responses, exhibited clear phasic responses to /t/ in the case when bursts of noise with particular central frequencies preceded the affricative consonant. The responsiveness of these neurons appears to receive temporal facilitation. These results suggest that these neurons code the temporal relationship of speech sound.Abbreviations
HVc
hyperstriatum ventrale, pars caudale
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TFN
temporally facilitated neuron
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TSN
temporally suppressed neuron 相似文献
5.
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7.
Signals of tens up to hundreds of thousands of (mostly olfactory) receptor cells on an insect antenna are switched to a comparatively low number of neurones in the antennal lobe of the deutocerebrum in circumscribed units of neuropile, the glomeruli. Each glomerulus is connected via its output neurone to two separate neuropiles (calyces of mushroom body, and lateral lobe) of the protocerebrum. Local interneurones interconnect between the glomeruli. Certain modes of convergence between receptors and central neurones provide for a very high sensitivity of the latter to certain odours and their sensitivity for complex odour stimuli, and in many cases for a marked multimodality. Anatomical and physiological data are given especially for pheromone sensitive neurones and their projections. 相似文献
8.
A. Mouras A. Lutz 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1983,64(4):283-288
Summary The determination of partial genotype, B/b and D/d, for coat colour in dogs, from phenotypic observations, is discussed. It is shown that the probability of a given genotype can be reliably determined where multiple observations on the mating of a given dog are available. 相似文献
9.
Behavioural evidence for colour vision in stomatopod crustaceans 总被引:2,自引:0,他引:2
N. J. Marshall J. P. Jones T. W. Cronin 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1996,179(4):473-481
If an organism can be taught to respond in a particular way to a wavelength of light, irrespective of that light's intensity, then it must be able to perceive the colour of the stimulus. No marine invertebrate has yet been shown to have colour vision. Stomatopod crustaceans (mantis shrimps) are colourful animals and their eyes have many adaptations which indicate that they are capable of such spectral analysis. We adopted an associative learning paradigm to attempt to demonstrate colour vision. Stomatopods readily learnt to choose some colours from arrays of greys, even when the correct choice colours were darker than the ones they had been trained to. Possible mechanisms underlying colour vision in these animals, and their ecological significance are discussed. A simple model is presented which may help interpret the complex-stomatopod colour vision system and explain some of the learning anomalies.Abbreviations
ND
neutral density
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OD
optical density
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R8
Retinular cell 8
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R1–7
Retinular cells 1–7
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R1D
Distally placed R1–7 retinular cells in mid-band row 1
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e.g. R1P
Proximally placed R1–7 retinular cells in mid-band row 1
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D/P
Estimate of chromatic signal ratio 相似文献
10.
Detection of coloured stimuli by honeybees: minimum visual angles and receptor specific contrasts 总被引:13,自引:0,他引:13
M. Giurfa M. Vorobyev P. Kevan R. Menzel 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1996,178(5):699-709
Honeybees Apis mellifera were trained to distinguish between the presence and the absence of a rewarded coloured spot, presented on a vertical, achromatic plane in a Y-maze. They were subsequently tested with different subtended visual angles of that spot, generated by different disk diameters and different distances from the decision point in the device. Bees were trained easily to detect bee-chromatic colours, but not an achromatic one. Chromatic contrast was not the only parameter allowing learning and, therefore, detection:
min, the subtended visual angle at which the bees detect a given stimulus with a probability P
0 = 0.6, was 5° for stimuli presenting both chromatic contrast and contrast for the green photoreceptors [i.e. excitation difference in the green photoreceptors, between target and background (green contrast)], and 15° for stimuli presenting chromatic but no green contrast. Our results suggest that green contrast can be utilized for target detection if target recognition has been established by means of the colour vision system. The green-contrast signal would be used as a far-distance signal for flower detection. This signal would always be detected before chromatic contrast during an approach flight and would be learned in compound with chromatic contrast, in a facilitation-like process. 相似文献