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   65349篇
  免费   2599篇
  国内免费   22篇
  2020年   683篇
  2019年   910篇
  2018年   1188篇
  2017年   1291篇
  2016年   1293篇
  2015年   911篇
  2014年   1139篇
  2013年   5009篇
  2012年   2074篇
  2011年   2127篇
  2010年   1322篇
  2009年   1275篇
  2008年   1890篇
  2007年   1874篇
  2006年   1735篇
  2005年   1538篇
  2004年   1473篇
  2003年   1356篇
  2002年   1406篇
  2001年   1982篇
  2000年   1853篇
  1999年   1453篇
  1998年   706篇
  1997年   639篇
  1992年   1182篇
  1991年   1092篇
  1990年   1133篇
  1989年   1042篇
  1988年   1069篇
  1987年   1015篇
  1986年   1037篇
  1985年   1039篇
  1984年   885篇
  1983年   845篇
  1982年   654篇
  1981年   631篇
  1979年   1011篇
  1978年   724篇
  1977年   618篇
  1976年   638篇
  1975年   843篇
  1974年   906篇
  1973年   956篇
  1972年   749篇
  1971年   723篇
  1970年   681篇
  1969年   751篇
  1968年   896篇
  1967年   793篇
  1966年   722篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
This study evaluated the clinical validity of the Intellectual Screening, Development, and Achievement scales of the Personality Inventory for Children-Revised (PIC-R), as well as the newly derived PIC-R Factor IV scale, in identifying cognitive impairment in a clinic-referred sample of preschoolers. The clinical validity of these PIC-R subscales was also compared to that of the Minnesota Child Development Inventory (MCDI). The results showed that the PIC-R scales and Factor IV were reasonably successful in identifying cognitively impaired preschoolers, but much less successful in identifying cognitively normal preschoolers. Overall, the MCDI was the most successful in correctly identifying the preschoolers' cognitive status.  相似文献   
942.
Subjects making lexical decisions are reliably faster in responding to high-frequency words than to low-frequency words. This is known as the word frequency effect. We wished to demonstrate that some portion of this effect was due to frequency differences between words rather than to other dimensions correlated with word frequency. Three groups of subjects (10 engineers, 10 nurses, and I0 law students) made lexical decisions about 720 items, half words and half nonwords, from six different categories (engineering, medical, low-frequency nontechnical, medium-frequency nontechnical, and two groups of high-frequency nontechnical). Results of two analyses of variance revealed a crossover interaction such that engineers were faster in responding to engineering words than to medical words, whereas nurses were faster in responding to medical words than to engineering words. The engineering and medical words were equally long and equally infrequent by standard word counts. We take this as support for a frequency-based component in the word frequency effect. The practical implications of this research for estimating the readability of technical text are discussed.  相似文献   
943.
Phonological coding in word reading: Evidence from hearing and deaf readers   总被引:14,自引:0,他引:14  
The ability of prelingually, profoundly deaf readers to access phonological information during reading was investigated in three experiments. The experiments employed a task, developed by Meyer, Schvaneveldt, and Ruddy (1974), in which lexical decision response times (RTs) to orthographically similar rhyming (e.g., WAVE-SAVE) and nortrhyming (e.g., HAVE-CAVE) word pairs were compared with RTs to orthographically and phonologically dissimilar control word pairs. The subjects of the study were deaf college students and hearing college students. In Experiments 1 and 2, in which the nonwords were pronounceable, the deaf subjects, like the hearing subjects, were facilitated in their RTs to rhyming pairs, but not to nonrhyming pairs. In Experiment 3, in which the nonwords were unpronounceable, both deaf and hearing subjects were facilitated in their RTs to both rhyming and nonrhyming pairs, with the facilitation being significantly greater for the rhyming pairs. These results indicate that access to phonological information is possible despite prelingual and profound hearing impairment. As such, they run counter to claims that deaf individuals are limited to the use of visual strategies in reading. Given the impoverished auditory, experience of such readers, these results suggest that the use of phonological information need not be tied to the auditory modality.  相似文献   
944.
The interactional teaching strategies of mothers and fathers toward their sociometrically determined popular, moderately popular, or unpopular children, and children's responses to them were examined during a structured puzzle task in a laboratory setting. Parents of popular children used more explanations in aiding their children to complete the puzzle task than parents of moderately popular or unpopular children. Mothers were more likely to offer suggestions, use explanations, and ask questions during the puzzle task than fathers. Analysis of children's responses revealed that popular children were more likely to ignore imperatives by their parents compared with unpopular children, while unpopular children showed a tendency to be more cooperative following imperatives by parents than popular children. Finally, popular children were less likely to ignore but were more likely to go off task following suggestions by parents than either unpopular or moderately popular children. The data are discussed with respect to the possible link between parental socialization patterns and children's popularity in the peer group and the need to consider the interaction patterns in both the peer and parent-child systems for intervention purposes.Portions of this paper were presented by the first author at the Banff International Conference on Behavioral Science, Banff, Alberta, Canada, 1984. The research was supported through the Western Regional Project W144, Development of Social Competencies in Children, with funding from Science and Education Administration/Cooperative Research of the USDA and Utah State University Agricultural Experiment Station. We would like to thank the parents and children for their participation, and Nina Mounts, Maria Norton, Carla Seamons, Soheila Sobhani, and Joan Wareham for their assistance with varying aspects of coding and data analysis.  相似文献   
945.
The influence of sexual experience on preference behavior was investigated in adult female rats. In the first experiment, preference behavior for sexually active males versus estrous females was investigated in female rats who were experienced with mounting behavior. Preference of these mount experienced females was compared to preference of females who were naive in this respect. Mount experience with estrous females induced a female-directed preference in ovariectomized female rats, irrespective of whether the females were treated with OIL or with testosterone-propionate (500 micrograms TP, injected once 48 h prior to testing). Sexually naive, OIL-treated females did not show a preference for males or females, but TP induced a preference for a male. Individual differences in mount frequency were not correlated with preference behavior. In the second experiment, the influence of experience with feminine sexual responses on preference behavior was investigated. OIL-treated and TP-treated females oriented equally toward males and females when they had been given the opportunity to copulate with males prior to the preference tests. The results strongly suggest that prior sexual experience is an important determinant of preference behavior. The female's behavior during sexual interactions was, however, not predictive of later preference.  相似文献   
946.
A long-term temporal component of working memory of rats trained on the radial maze has been shown to be susceptible to disruption by the protein synthesis inhibitor, anisomycin. It is not clear whether protein synthesis played a role in working memory because accurate performance on the radial maze required the storage of a large amount of information, or because the information was to be held in store for relatively long periods of time. This experiment tested these hypotheses by assessing the effect of anisomycin on choice accuracy in a comparatively simple spatial delayed alternation task. Results indicate that under the present training conditions, protein involvement in working memory is related more to the length of the retention interval than to the amount of information retained.  相似文献   
947.
Previous research suggests that gut distension by ingested bulk plays an important role in the regulation of food intake in gastropod molluscs. The present study tested whether the bilateral stomatogastric nerves which innervate the esophagus and crop in Pleurobranchaea form a neural pathway carrying information about gut distension to the central nervous system. The posterior branches of the paired stomatogastric nerves were surgically exposed and sectioned in seven experimental animals while the nerves were simply exposed and not sectioned in seven sham-operated control animals. In three, subsequent, daily feeding sessions, the experimental subjects consumed a greater amount of food in terms of percentage of body weight than the control subjects. The experimental animals also gained a greater percentage of body weight and later were found to contain much more food within their guts. The results support the hypothesis that stretch receptors which innervate the gut and which have axons in the stomatogastric nerves form an important negative feedback pathway for the control of feeding in the sea slug.  相似文献   
948.
A series of behavioral bioassays were conducted to determine the aggression-influencing properties of urine and other fluids. Subjects were prepuberal castrated male and female domestic pigs from commercial stocks. In the behavior assay, pigs were painted with a test fluid and grouped for a videotaped 90 min observation period. Experiment 1 validated use of videotape recording by showing that duration of aggressive behavior registered live was correlated with that obtained from video records (R = .98). In experiment 2, urine and plasma collected from actively aggressive pigs reduced the durations of aggressive behavior of test pigs compared with the effects of urine and plasma collected from socially stable, handled pigs. In Experiment 3, a new set of test pigs confirmed that urine from fighting pigs reduced the duration of attack by test pigs compared with urine from nonfighting, handled pigs. In addition, the suggested reproductive pheromone, 5 alpha-androst-16-en-3-one, substantially reduced the duration of attack. The effects of gender and aggressive state of urine-donor pigs on test pigs was determined in Experiment 4. Again, urine from castrated male and female aggressive pigs reduced attack by test pigs compared with the level of attack shown by test pigs coated with urine from handled castrated males and females. Urine from fighting and nonfighting intact males had similar effects on test pig aggression. In Experiment 5, urine was obtained from nonhandled, socially stable pigs in their home pens and again from the same pigs after they had been regrouped (aggressive). These urine types had no significant influence on test pigs' aggression over the entire 90-min observation. However, during the first 30 min nonhandled, nonfighting pigs' urine induced less aggression in test pigs than did urine from fighting pigs. Results indicate that urine and blood plasma from aggressive pigs reduces aggression by test pigs compared with the effects of urine from handled pigs. Handling may increase the aggression-promoting properties of urine, and aggression may inhibit this aggression-promoting property.  相似文献   
949.
Modulation of male urogenital sniff, attack, and mount behaviors by urinary cues from female mice (SJL/J) was assessed in two experiments. Experiment 1 examined the efficacy of urine from ovariectomized and intact females in modulating the behavior of sexually experienced and inexperienced males vis-à-vis the control substance, water. It was found that urine from ovariectomized females showed no behavior-modulating properties, whereas urine from intact females decreased attack but increased sniff and mount behaviors in male mice. These findings are indicative of ovarian-dependent chemosignals contained in the urine of only intact females. Prior sexual experience had no effect on behavior of males when exposed to urine from ovariectomized females. Sniff and mount behaviors were, however, increased when sexually experienced males were exposed to urine from intact females. Using sexually inexperienced males, Experiment 2 assessed the chemosignal activity of urine from females in each of four estrous phases. It was determined that urine from proestrous and estrous females increased sniff and mount behaviors and decreased attack behavior. Urine from metaestrous females was shown to possess only sniff-inducing and mount-reducing chemosignal properties. Urine from females in diestrous lacked attack- and mount-modulating chemocues but may possess a sniff-inducing chemosignal.  相似文献   
950.
This psychophysiological evaluation of an aerobic exercise program examined specifically whether aerobic training modified Pattern A for those individuals at behavioral risk for developing coronary heart disease, i.e., young Type A individuals. At pretest and posttest of this secondary prevention study, Type A and Type B subjects were assessed in three conditions: aerobic exercise program, nonaerobic activity (Aikido, a martial art) control, and notreatment control. After 10 weeks, Type A but not Type B subjects exhibited lower Pattern A behavior in the aerobic program than in control conditions. Average workout pulse rates and differentially reliable increases in aerobic capacity indicated that aerobic training was indeed aerobic, whereas aikido activity was not. Even though selected nonaerobic factors, such as locus of control and group participation, did not mediate the Pattern A decrease for Type A's when comparing aikido and aerobic conditions, changes in aerobic capacity may have been the mediator. Generalizability of the results and implications for theoretical development and clinical intervention are discussed.  相似文献   
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