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641.
Plasma membrane ordering agent pluronic F-68 (PF-68) reduces neurotransmitter uptake and release and produces learning and memory deficits in rats 总被引:4,自引:0,他引:4 下载免费PDF全文
A substantial body of evidence indicates that aged-related changes in the fluidity and lipid composition of the plasma membrane contribute to cellular dysfunction in humans and other mammalian species. In the CNS, reductions in neuronal plasma membrane order (PMO) (i.e., increased plasma membrane fluidity) have been attributed to age as well as the presence of the β-amyloid peptide-25-35, known to play an important role in the neuropathology of Alzheimer's disease (AD). These PMO increases may influence neurotransmitter synthesis, receptor binding, and second messenger systems as well as signal transduction pathways. The effects of neuronal PMO on learning and memory processes have not been adequately investigated, however. Based on the hypothesis that an increase in PMO may alter a number of aspects of synaptic transmission, we investigated several neurochemical and behavioral effects of the membrane ordering agent, PF-68. In cell culture, PF-68 (nmoles/mg SDS extractable protein) reduced [3H]norepinephrine (NE) uptake into differentiated PC-12 cells as well as reduced nicotine stimulated [3H]NE release. The compound (800–2400 μg/kg, i.p., resulting in nmoles/mg SDS extractable protein in the brain) decreased step-through latencies and increased the frequencies of crossing into the unsafe side of the chamber in inhibitory avoidance training. In the Morris water maze, PF-68 increased the latencies and swim distances required to locate a hidden platform and reduced the time spent and distance swam in the previous target quadrant during transfer (probe) trials. PF-68 did not impair performance of a well-learned working memory task, the rat delayed stimulus discrimination task (DSDT), however. Studies with 14C-labeled PF-68 indicated that significant (pmoles/mg wet tissue) levels of the compound entered the brain from peripheral (i.p.) injection. No PF-68 related changes were observed in swim speeds or in visual acuity tests in water maze experiments, rotorod performance, or in tests of general locomotor activity. Furthermore, latencies to select a lever in the DSDT were not affected. These results suggest that PF-68 induced deficits in learning and memory without confounding peripheral motor, sensory, or motivational effects at the tested doses. Furthermore, none of the doses induced a conditioned taste aversion to a novel 0.1% saccharin solution indicating a lack of nausea or gastrointestinal malaise induced by the compound. The data indicate that increases in neuronal plasma membrane order may have significant effects on neurotransmitter function as well as learning and memory processes. Furthermore, compounds such as PF-68 may also offer novel tools for studying the role of neuronal PMO in mnemonic processes and changes in PMO resulting from age-related disorders such as AD. 相似文献
642.
The articles in this volume present a unique perspective on participatory evaluation of development programs and projects. The authors are all evaluators and researchers who reside in the South or have extensive Third World experience. They present a broad range of insight into the forms of participation that are feasible and desirable in the evaluation of development activities. 相似文献
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Donald J. Willower Wayne K. Hoy Terry L. Eidell 《Journal of counseling and development : JCD》1967,46(3):228-234
Role relations in the public school are viewed within the perspective of organization theory; the public school is like the prison and the public mental hospital in that neither client nor organization exercises choice concerning client participation in the organization. Based on previous studies of prisons and mental hospitals and on clues provided in a case study of a junior high school, it was predicted that counselors and principals would be less “custodial” in pupil control ideology than teachers. An instrument that measured pupil control ideology along a custodial-humanistic continuum was administered to 945 teachers, 181 principals, and 180 counselors. Results confirmed the predictions. Counselor adaptations to ideological conflict concerning pupil control in both the secondary and the elementary school are discussed. It was speculated that adaptations would function to reduce overt conflict and contribute to organizational equilibrium. 相似文献
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The major purpose of this study was to investigate the effects of stimulus complexity, novelty, and affective tone on the direction of eye movements of male college students. Motion pictures were taken of S’s eye while he viewed pairs of stimuli. In no instance, in any part of the 10 sec. viewing interval, did Ss as a group fixate longer on unpleasant stimuli when they were paired with either pleasant or neutral stimuli; and pleasant stimuli consistently dominated neutral stimuli. Also, novel stimuli and complex stimuli tended to dominate their non-novel and less complex competitors. Differences in instructions were found to markedly affect the magnitude but not the direction of fixation-dominance. 相似文献
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In this research, a conceptual framework is developed that addresses the impact of typeface semantic cues within a marketing context. Visual properties of typefaces are conceptualized as communicating unique semantic associations to individuals distinct from the content of the written words they clothe. Typeface associations are investigated across varying levels of involvement in terms of their effect upon brand perceptions. These associations also influenced the memorability of advertised benefit claims. Memorability was enhanced as the degree of consistency among typeface semantic cues, advertisement visual cues, and advertisement copy claims increased. Extensions of this framework focus on obtaining a more complete understanding concerning the semantic pathways through which typefaces convey meaning. 相似文献
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Paul S. Bay Daniel Beckman James Trippi Richard Gunderman Colin Terry 《Journal of religion and health》2008,47(1):57-69
This randomized controlled study measured the effect of chaplain interventions on coronary artery bypass graft (CABG) patients
over time. One hundred sixty-six CABG patients, received pre- and post-surgery testing at 1 month and 6 months with four instruments.
Five chaplain visits were made to the intervention group, the control group received none. Comparison scores for anxiety,
depression, hope, positive and negative religious coping, and religious coping styles were analyzed. Significant difference
was found between groups in positive religious coping (PRC) (p = .023) and negative religious coping (NRC) (p = .046) scores over time. PRC increased in intervention group, decreased in the control group while NRC decreased in intervention
group and increased in the control group. Demographics were comparable between groups. Moderate chaplain visits (average total
visits time, 44 min) may be effective in helping CABG patients increase positive religious coping and decrease negative religious
coping.
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Paul S. BayEmail: |