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   23013篇
  免费   772篇
  国内免费   11篇
  2020年   213篇
  2019年   218篇
  2018年   336篇
  2017年   380篇
  2016年   373篇
  2015年   242篇
  2014年   319篇
  2013年   1741篇
  2012年   617篇
  2011年   678篇
  2010年   412篇
  2009年   390篇
  2008年   585篇
  2007年   570篇
  2006年   516篇
  2005年   466篇
  2004年   450篇
  2003年   418篇
  2002年   475篇
  2001年   739篇
  2000年   767篇
  1999年   561篇
  1998年   264篇
  1997年   223篇
  1992年   461篇
  1991年   413篇
  1990年   453篇
  1989年   421篇
  1988年   408篇
  1987年   411篇
  1986年   413篇
  1985年   425篇
  1984年   344篇
  1983年   306篇
  1982年   244篇
  1981年   216篇
  1979年   392篇
  1978年   289篇
  1977年   258篇
  1976年   229篇
  1975年   348篇
  1974年   380篇
  1973年   356篇
  1972年   334篇
  1971年   293篇
  1970年   266篇
  1969年   324篇
  1968年   366篇
  1967年   324篇
  1966年   328篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
201.
Eye movement control in reading: evidence against semantic preprocessing.   总被引:3,自引:0,他引:3  
Prior experiments reported by Underwood and his colleagues have suggested that information about the informative parts of parafoveal words that have not yet been fixated can influence where readers fixate next. The basic finding that they have reported is that the eyes move farther into a word when the information that uniquely identifies the word is at the end of the word rather than at the beginning of the word. On the basis of such results, it has been suggested that semantic preprocessing influences eye movement behavior in reading. Some theoretical and methodological problems are raised with the prior experiments and then an attempt to replicate the finding is reported. With a highly accurate eyetracking system, the basic finding could not be replicated. An alternative account of eye movement control in reading is discussed.  相似文献   
202.
The use of neurological tests in various states of undernutrition has confirmed the presence of delays in reflex ontogeny. Glucocorticoid administration in conditions of normal nutrition produces diminished growth and alterations in brain development similar to those observed in malnutrition, but there is not enough evidence about its effect on reflex development. In addition, some facts lead us to think that the use of permissive doses of these hormones during gestation could alleviate some of the effects of protein malnutrition on the development of pups. In the present study the ages at which certain reflexes appeared in the offspring of Wistar rats (Rattus norvegicus) fed a 20% (N) or 10% (M) protein diet from a week before conception to the end of lactation were observed. Each dietary group was subdivided into two: mothers receiving a daily injection during gestation either of a 0.9% NaCl (S) solution or of a 0.5 mg/100 g weight hydrocortisone acetate (C) solution. Results showed that the NS group of pups generally presented earlier ages of appearance of the variables under study than the remaining groups. Pups of the NC group presented delays in the age of appearance of reflexes. Finally, protein malnutrition delayed the appearance of reflexes and this effect seemed to be attenuated by treatment with hydrocortisone. Thus, hydrocortisone administration in protein malnutrition conditions seems to be beneficial although the results are harmful when administered under normal nutritional conditions.  相似文献   
203.
Learning a bimanual coordination task (synchronization to a visually specified phasing relation) was studied as a dynamical process over 5 days of practicing a required phasing pattern. Systematic probes of the attractor layout of the 5 Ss' coordination dynamics (expressed through a collective variable, relative phase) were conducted before, during, and after practice. Depending on the relationship between the initial coordination dynamics (so-called intrinsic dynamics) and the pattern to be learned (termed behavioral information, which acts as an attractor of the coordination dynamics toward the required phasing), qualitative changes in the phase diagram occurred with learning, accompanied by quantitative evidence for loss of stability (phase transitions). Such effects persisted beyond 1 week. The nature of change due to learning (e.g., abrupt vs. gradual) is shown to arise from the cooperative or competitive interplay between behavioral information and the intrinsic dynamics.  相似文献   
204.
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   
205.
The present experiment shows that a conditioned taste aversion procedure can support discrimination learning at dosages of morphine comparable to those required to produce motivational effects. Sprague-Dawley rats were injected with 4.0 mg/kg morphine sulfate prior to a saccharin-lithium chloride pairing, and physiological saline prior to a saccharin-saline pairing. The rats avoided the saccharin solution following the administration of morphine and consumed significantly more saccharin following saline administration after four discrimination cycles. After this initial discrimination the subjects were trained with progressively lower doses of morphine. Discrimination learning was apparent at doses of 2.0, 1.5, 1.0, 0.75 and 0.5 mg/kg. Animals initially trained with 1.0 mg/kg morphine also learned the discrimination but required 10 training cycles. After this initial discrimination the subjects were trained with progressively lower dosages of morphine and showed a discrimination at a dosage of 0.5 mg/kg.  相似文献   
206.
From previous research, the ultrasonic vocalizations of male mice (Mus domesticus) to female mouse urine were hypothesized to be learned as a result of classical conditioning during adult heterosexual encounters. According to this interpretation, a previously neutral conditioned stimulus in female urine comes to elicit vocalizations as a result of its association with some other unknown unconditioned stimulus associated with adult females. However, the research from which this hypothesis was derived utilized urine collected from females housed in metabolic cages. Three experiments further examined the classical conditioning hypothesis using two types of female urine: (i) metabolic-cage-collected urine and (ii) freshly voided urine. Experiment 1 demonstrated that, in contrast to vocalizations to metabolic-cage-collected urine, adult heterosexual experience was not necessary for males to vocalize to freshly voided female urine. In addition, unlike metabolic-cage-collected urine (Experiment 3), freshly voided urine remained a potent stimulus for eliciting vocalizations during repeated testing (Experiments 2 and 3). Finally, freshly voided urine appeared to cause a previously neutral stimulus (cotton swab) to acquire ultrasound eliciting properties (Experiment 2). We suggest from these findings that two chemosignals that elicit vocalizations from males may exist in female mouse urine: (i) a potent, but volatile or easily degraded, unconditioned stimulus to which males vocalize without sexual experience and (ii) a nonvolatile, chemically stable conditioned stimulus.  相似文献   
207.
Patterns of coping with cancer.   总被引:12,自引:0,他引:12  
We identified five patterns of coping in a sample of 603 cancer patients: "seeking or using social support," "focusing on the positive," "distancing," "cognitive escape-avoidance," and "behavioral escape-avoidance." Relationships of these coping patterns to sociodemographic characteristics, medical factors, stress appraisals, psychotherapeutic experience, and emotional distress were tested using correlational and regression techniques. Type of cancer, time since diagnosis, and whether a person was currently in treatment had few or no relationships to coping. The specific cancer-related problem (e.g., pain, fear of future) was also not associated with how individuals coped. Perceptions of its stressfulness, however, were related to significantly more coping through social support and more of both forms of escape-avoidance. Coping through social support, focusing on the positive, and distancing was associated with less emotional distress, whereas using cognitive and behavioral escape-avoidance was associated with more emotional distress. Implications of the results for understanding coping processes and intervention with cancer patients are discussed.  相似文献   
208.
This article describes a study conducted to identify the range of potential influences that a computer-assisted careers guidance system (PROSPECT (HE)) had on the functioning of organisations (careers services in higher education). Data from six institutions indicated that use of PROSPECT (HE) was associated with important and varied change within the organisations. It appears that when a careers service seeks opportunities for change, CACG systems can be an important catalyst for change in two respects: by providing a focal point for achieving previously established goals; or, as a consequence of system use, by making staff aware of the potential for new organisational goals.  相似文献   
209.
210.
Two experiments are reported which investigated how subject gender and time-of-day influenced the estimation of duration and the perception of task-related mental workload. In the first experiment, 24 subjects performed a filled time-estimation task in a constant blacked-out, noise-reduced environment at 0800h, 1200h, 1600h, and 2000h, respectively. In the second experiment, 12 different subjects performed an unfilled time estimation task in similar conditions at 0900h, 1400h, and 1900h. At the termination of all experimental sessions, participants completed the NASA Task Load Index workload assessment questionnaire as a measure of perceived mental workload. Results indicated that physiological response, reflected in body temperature change, followed an expected pattern of sequential increase with time-of-day. However, estimates of duration and the perception of mental workload showed no significant effects for time-of-day. In each of the experiments there were significant differences in time estimation and mental workload response contingent on the gender of the participant. These results are interpreted in light of the previous positive findings for circadian fluctuation in performance efficiency and the equivocal findings of a gender difference in time estimation. A unifying account of these collective results is given based on gender by time-of-day interactional effects. An earlier version of this paper was presented at the 32nd Annual Meeting of the Human Factors Society, Anaheim, CA, October, 1988.  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