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151.
152.
Osamu Shouno Koichi Kokame Masasuke Araki †Toshifumi Takao †Yasutsugu Shimonishi ‡Masayuki Murata §Tôru Yoshizawa Yoshitaka Fukada 《Journal of neurochemistry》1996,66(5):2188-2196
Abstract: The photoreceptor G protein transducin [α- and βγ-subunits (Tα/Tβγ)] plays a central role in the visual transduction process. The amino-terminus of bovine Tα is modified by one of four distinct fatty acids—laurate (C12:0), myristate (C14:0), C14:1 (5- cis ), and C14:2 (5- cis , 8- cis )—but the biological significance and the localization of the four isoforms of Tα are poorly understood. To investigate the cellular distribution of each isoform, we prepared monoclonal antibodies against a synthetic C12:0-, C14:0-, C14:1-, or C14:2-nonapeptide corresponding to the N-terminal region of Tα. Among several types of antibodies isolated, only one type, represented by LA4, reacted specifically with the C12:0-peptide as well as purified Tα but not with the other proteins in bovine retinal homogenate, including recoverin, indicating that the epitope comprises both C12:0 and the N-terminal amino acids of Tα. Immunohistochemical analyses of bovine retinal sections by LA4 showed the uniform distribution of C12:0-Tα in almost all the rod outer segments. Hence, it seemed unlikely that each isoform of Tα was localized in specific cells. This observation, together with evidence for a possible functional diversity among the isoforms, suggests that the four isoforms of Tα in a single rod cell may contribute simultaneously to a fine tuning of the photon-signal transduction process. 相似文献
153.
Henny J. van der Meer Gerrit Ch. Anker Cornelis D. N. Barel 《Environmental Biology of Fishes》1995,44(1-3):115-132
Synopsis Before the decline of the species flock of haplochromine cichlids of Lake Victoria due to the Nile perch upsurge, there were many co-existing haploehromine species such as the taxonomically and ecologically well-studied zooplanktivores of the Mwanza Gulf. In spite of the scarcely separated niches of some of these species, no sign of competition for space or food could be demonstrated. As is argued in this paper, optical differentiation could well be an aspect of adaptive radiation of these zooplanktivores, particularly among the highly sympatric species. Our hypothesis is based on the morphological modifications of retinal structures in nine zooplanktivorous species. Interspecific variation was observed in composition, size and density of the photoreceptors and ganglion cells. The analyses included the intraretinal variation and size dependency of some of the structural parameters. The optical functions deduced from retinal structure indicate distinct interspecific differences in sensitivity thresholds and a slight differentiation in visual resolution. These functions correlate poorly with the photic conditions of the species-specific habitats. The optical properties can, on the other hand, be connected with the more subtle differentiation in food items and feeding behaviour among these species. It is our concluding hypothesis, that the optical differentiation among the haplochromine zooplanktivores primarily served resource partitioning by different modes of visual prey detection rather than niche partitioning by habitat. 相似文献
154.
Choline acetyltransferease (ChAT) is the enzyme catalyzing the biosynthesis of acetylcholine and is considered to be a phenotypically specific marker for cholinergic neurons. We have examined the distribution of ChAT-expressing neurons in the larval nervous system of Drosophila melanogaster by three different but complementary techniques: in situ hybridization with a cRNA probe to ChAT messenger RNA, immunocytochemistry using a monoclonal anti-ChAT antibody, and X-gal staining of transformed animals carrying a reporter gene composed of 7.4 kb of 5 flanking DNA from the ChAT gene fused to a lacZ reporter gene. All three techniques demonstrated ChAT-expressing neurons in the larval visual system. In embryos, the photoreceptor organ (Bolwig's organ) exhibited strong cRNA hybridization signals. The optic lobe of late third-instar larvae displayed ChAT immunoreactivity in Bolwig's nerve and a neuron close to the insertion site of the optic stalk. This neuron's axon ran in parallel with Bolwig's nerve to the larval optic neuropil. This neuron is likely to be a first-order interneuron of the larval visual system. Expression of the lacZ reporter gene was also detected in Bolwig's organ and the neuron stained by anti-ChAT antibody. Our observations indicate that acetylcholine may be a neurotransmitter in the larval photoreceptor cells as well as in a first-order interneuron in the larval visual system of Drosophila melanogaster.This work was supported by a grant from the National Institute of Neurological Disorders and Stroke. 相似文献
155.
J. M. Ellingson L. J. Fleishman E. R. Loew 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1995,177(5):559-567
The visual pigments and oil droplets in the retina of the diurnal gecko Gonatodes albogularis were examined microspectrophotometrically, and the spectral sensitivity under various adapting conditions was recorded using electrophysiological responses. Three classes of visual pigments were identified, with max at about 542, 475, and 362 nm. Spectral sensitivity functions revealed a broad range of sensitivity, with a peak at approximately 530–540 nm. The cornea and oil droplets were found to be transparent across a range from 350–700 nm, but the lens absorbed short wavelength light below 450 nm. Despite the filtering effect of the lens, a secondary peak in spectral sensitivity to ultraviolet wavelengths was found. These results suggest that G. albogularis does possess the visual mechanisms for discrimination of the color pattern of conspecifics based on either hue or brightness. These findings are discussed in terms of the variation in coloration and social behavior of Gonatodes.Abbreviations
ERG
electroretinogram
-
MSP
microspectrophotometry
-
UV
ultraviolet
- max
wavelength of maximum absorbance 相似文献
156.
M. Sasaki A. Masuda T. Oishi 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1995,176(4):465-471
We investigated circadian ocular rhythms in the Japanese quail, Coturnix coturnix japonica. The birds were placed under light-dark cycles (LD 1212), constant light (LL) and constant darkness (DD), and the retinas were dissected out at four-hour intervals throughout 24 h. Following measurements were performed. (1) Melatonin content in the retina was measured by radioimmunoassay. It was low in light and several folds higher in darkness under LD 1212. The rhythm continued in DD, but disappeared in LL. (2) Mitotic figures in the corneal epithelium were counted. Similar rhythms to the melatonin content were observed in the corneal mitotic rate with a slight phase delay. (3) The retinas were fixed at 4-h intervals and immunostained with anti-bovine rhodopsin serum and anti-chicken iodopsin monoclonal antibodies. The outer segments of photoreceptor cells were stained intensively throughout 24 h in LD 1212, LL and DD. In contrast, the stainability of the locus close to the outer limiting membrane where the Golgi apparatus exists changed diurnally. Scores showing the ratio of cells with positive staining indicated high values from 4 h after the onset of light to the beginning of dark phase under LD 1212. The values were high throughout 24 h in LL and intermediate or low in DD. (4) To investigate the effect of melatonin on the corneal mitotic rate and visual pigments at the Golgi region, melatonin was injected into one eye and saline into the contralateral eye. Melatonin induced a phase advance in the corneal mitotic rate under LD 1212, but did not induce a rhythm under LL. The ratio of photoreceptor cells with positive staining to anti-visual pigment antibodies at the Golgi region was not affected by melatonin injection.Abbreviations
ANOVA
analysis of variance
-
BSA
bovine serum albumin
-
DD
constant darkness
-
Io-mAb
monoclonal antibodies against chicken iodospin
-
LD
light-dark
-
LL
constant light
-
mRNA
messenger ribonucleic acid
-
PBS
phosphate buffer solution
-
Rh-As
antiserum against bovine rhodopsin
-
SCN
suprachiasmatic nucleus
-
T
transducin
-
T
transducin 相似文献
157.
Abstract: Light activation of rhodopsin in the Drosophila photoreceptor induces a G protein-coupled signaling cascade that results in the influx of Ca2+ into the photoreceptor cells. Immediately following light activation, phosphorylation of a photoreceptor-specific protein, phosrestin I, is detected. Strong sequence similarity to mammalian arrestin and electroretinograms of phosrestin mutants suggest that phosrestin I is involved in light inactivation. We are interested in identifying the protein kinase responsible for the phosphorylation of phosrestin I to link the transmembrane signaling to the light-adaptive response. Type II Ca2+ /calmodulin-dependent kinase is one of the major classes of protein kinases that regulate cellular responses to transmembrane signals. We show here that partially purified phosrestin I kinase activity can be immunodepleted and immunodetected with antibodies to Ca2+ /calmodulin-dependent kinase II and that the kinase activity exhibits regulatory properties that are unique to Ca2+ /calmodulin-dependent kinase II such as Ca2+ independence after autophosphorylation and inhibition by synthetic peptides containing the Ca2+ /calmodulin-dependent kinase II autoinhibitory domain. We also show that Ca2+ /calmodulin-dependent kinase II activity is present in Drosophila eye preparations. These results are consistent with our hypothesis that Ca2+ /calmodulin-dependent kinase II phosphorylates phosrestin I. We suggest that Ca2+ /calmodulin-dependent kinase II plays a regulatory role in Drosophila photoreceptor light adaptation. 相似文献
158.
159.
T. Amundsen E. Forsgren L. T. T. Hansen 《Proceedings. Biological sciences / The Royal Society》1997,264(1388):1579
Female ornaments in animals with conventional sex roles have traditionally been considered non-functional, being merely a genetically correlated response to selection for male ornamentation. Alternatively, female ornaments may be influenced by selection acting directly on the females, either through female–female competition or male choice. We tested the latter hypothesis in mate choice experiments with bluethroats (Luscinia s. svecica), a passerine bird in which females vary considerably in coloration of an ornamental throat patch. In outdoor aviaries placed in prime breeding habitat, males were allowed to choose between a colourful and a drab female. We found that males associated more with, and performed more sexual behaviours towards, colourful females. Female coloration was not age-related, but correlated significantly with body mass and tarsus length. Thus, we have demonstrated both a male preference for female ornamentation, and a relationship between ornament expression and female body size, which may be indicative of quality. Our results refute the correlated response hypothesis and support the hypothesis that female ornamentation is sexually selected. 相似文献
160.
The electroretinographic spectral sensitivity of the cricket compound eyes shows the presence of two receptor types, a dominant one at 520 nm and another in the near-u.v. (λmax 355 ± 5 nm) under dark- and intense chromatic adaptation conditions (Fig. 3). The waveform of the electrical responses elicited by short-wavelength stimuli differ from those elicited by long wavelength stimuli (Fig. 1). 相似文献