首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   193258篇
  免费   8460篇
  国内免费   169篇
  201887篇
  2020年   2885篇
  2019年   3533篇
  2018年   3935篇
  2017年   4326篇
  2016年   4938篇
  2015年   4018篇
  2014年   4906篇
  2013年   23913篇
  2012年   5423篇
  2011年   4664篇
  2010年   4347篇
  2009年   4998篇
  2008年   4760篇
  2007年   4295篇
  2006年   4668篇
  2005年   4565篇
  2004年   3960篇
  2003年   3588篇
  2002年   3419篇
  2001年   4124篇
  2000年   3958篇
  1999年   3687篇
  1998年   2893篇
  1997年   2717篇
  1996年   2638篇
  1995年   2483篇
  1994年   2440篇
  1993年   2387篇
  1992年   3067篇
  1991年   2872篇
  1990年   2759篇
  1989年   2606篇
  1988年   2595篇
  1987年   2566篇
  1986年   2570篇
  1985年   2738篇
  1984年   2772篇
  1983年   2511篇
  1982年   2434篇
  1981年   2411篇
  1980年   2271篇
  1979年   2557篇
  1978年   2333篇
  1977年   2260篇
  1976年   2114篇
  1975年   2288篇
  1974年   2368篇
  1973年   2321篇
  1972年   1843篇
  1971年   1764篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
The local anesthetic lidocaine (XILOCAINA), 2%, was injected into the tissue surrounding the anterior region of the third cerebral ventricle (AV3V) of the rat, through a permanently implanted cannula, to produce a temporary and reversible disruption of the nervous connections of this area with other cellular nuclei while leaving the vascular connections intact. Following 24 h water deprivation, lidocaine was injected, and after 20 min water intake decreased; subsequently, the lidocaine-injected rats behaved similarly to control rats injected with artificial cerebrospinal fluid. Osmotic drinking was not affected. Prolonged adipsia or hyperdipsia did not occur. In nondeprived rats, lidocaine prevented angiotensin II-induced drinking. Following 24 h sodium depletion by peritoneal dialysis, lidocaine decreased the specific sodium appetite by 50% in animals with different levels of body sodium depletion. The data indicate that the integrity of the neural tissue of the AV3V is essential for a correct body water-salt regulation. Temporary "ablation" with lidocaine, which blocked neural activity but maintained the blood supply, produced responses different from most of those reported after electrolytic lesions. Therefore, lidocaine may be used as a tool to assess the response of this neural tissue to body fluid regulation.  相似文献   
992.
Reports that the dihydropyridine Ca2+ channel antagonists may facilitate memory led to the present study of the behavioral effects of nifedipine. Ninety-two 4-day-old male chicks received 0, 100 nM, 100 microM, or 10 mM nifedipine. Drugs were administered in volumes of 2 microliters into the fourth cerebral ventricle 5 min before training on a visual discrimination task. Nifedipine did not produce any detectable changes in behavior during acquisition trials. Retention, however, was impaired 24 h after training in the 100 nM and 100 microM nifedipine-treated chicks, which made significantly more errors than controls. Nifedipine did not affect the amount of time required to complete the task. No effects on body weight gain were detected, suggesting that the memory impairment was not due to a change in feeding behavior. These data are discussed in terms of the role of calcium-dependent processes in memory.  相似文献   
993.
According to a conditioning analysis of the orientation-contingent color aftereffect (McCollough effect, ME), orientation stimulus (grids) become associated with color. Contrary to this interpretation are reports that simple forms cannot be used to elicit illusory color and that the ME is not degraded by decreasing the grid-color correlation. The present results indicate: (a) Form stimuli can contingently elicit color aftereffects; (b) even a non-patterned stimulus--the lightness of a frame surrounding a colored area--can contingently elicit color aftereffects; (c) this frame lightness-contingent aftereffect, like the ME, persists for at least 24 hr; and (d) the frame lightness-contingent aftereffect can be used to demonstrate that correlational manipulations affect the ME, as they affect other types of conditional responses.  相似文献   
994.
Cerella (1991) has argued that the performance of older adults in the Fisk and Rogers (1991) study is a linear function of the performance of younger adults that is independent of task-specific cognitive requirements. We demonstrate that this is not the case. First, we show that the scatter plot analyses used by Cerella can hide the very task-specific age-related slowing they were designed to reveal. Second, we demonstrate that the percentage of variance explained by such analyses can be misleading. Third, we show that there are reliable differences across tasks in the parameters relating younger and older adults' performance. Finally, we argue that the general, task-independent proportionate slowing that Cerella suggested explains so much of the variance in age-related performance is actually an average slowing that is a function of a relatively small task-independent and a relatively large task-dependent factor.  相似文献   
995.
Conditional stimuli (CS) associated with painful unconditional stimuli (US) produce a naloxone-reversible analgesia. The analgesia serves as a negative-feedback regulation of fear conditioning that can account for the impact of US intensity and CS predictiveness on Pavlovian fear conditioning. In Experiment 1 training under naloxone produced learning curves that approached the same high asymptote despite US intensity. Shifting drug treatment during acquisition had effects that paralleled US intensity shifts. In Experiment 3 naloxone reversed Hall-Pearce (1979) negative transfer using a contextual CS, indicating that conditional analgesia acquired during the CS-weak-footshock phase retards acquisition in the CS-strong-footshock phase. Experiment 5 used a tone CS in both a latent-inhibition and a negative-transfer procedure. Only negative transfer was blocked by naloxone. Therefore, negative transfer but not latent inhibition is mediated by a reduction of US processing.  相似文献   
996.
997.
A multivariate hierarchical model of specific cognitive abilities was fitted to data from 7-year-old adopted and nonadopted sibling pairs in the Colorado Adoption Project in order to assess differential genetic influence on specific mental abilities. Model fitting results and Schmid-Leiman (Schmid & Leiman, 1957) transformations reveal significant heritable variation for verbal, spatial, and memory factors independent of general cognitive ability for the eight ability tests examined. In contrast, environmental influences are primarily measure-specific. The results suggest genetic effects in middle childhood that differentially influence mental ability scores.  相似文献   
998.
A feminist psychospiritual model of therapy that can be used in working with clients who value the spiritual dimension in their lives is offered. The history, philosophy, and work of Women for a New World, a multidisciplinary team of women representing the areas of psychology, religious education, and the arts is presented. Using examples drawn from the developmental history of our retreat-workshop paradigm and from some of our programs, including a weekend retreat for women and a day of reflection for persons affected by AIDS (including family and friends of those with AIDS), the metaphor of therapy as soul healing is developed.  相似文献   
999.
Surprisingly little has been written in the counseling journals on the topic of lying: that is, why some clients consciously choose to be either dishonest with their counselors or deliberately hold back (i.e., keep secrets) important information from their counselors. This article discusses the dynamics of lying and offers suggestions to counselors on how to work with clients who lie.  相似文献   
1000.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号