全文获取类型
收费全文 | 24683篇 |
免费 | 1106篇 |
国内免费 | 16篇 |
专业分类
25805篇 |
出版年
2020年 | 347篇 |
2019年 | 411篇 |
2018年 | 606篇 |
2017年 | 583篇 |
2016年 | 608篇 |
2015年 | 440篇 |
2014年 | 536篇 |
2013年 | 2329篇 |
2012年 | 945篇 |
2011年 | 1004篇 |
2010年 | 617篇 |
2009年 | 611篇 |
2008年 | 855篇 |
2007年 | 832篇 |
2006年 | 828篇 |
2005年 | 730篇 |
2004年 | 687篇 |
2003年 | 679篇 |
2002年 | 681篇 |
2001年 | 661篇 |
2000年 | 618篇 |
1999年 | 489篇 |
1998年 | 307篇 |
1997年 | 295篇 |
1996年 | 289篇 |
1995年 | 265篇 |
1994年 | 238篇 |
1993年 | 244篇 |
1992年 | 349篇 |
1991年 | 365篇 |
1990年 | 333篇 |
1989年 | 327篇 |
1988年 | 294篇 |
1987年 | 301篇 |
1986年 | 301篇 |
1985年 | 334篇 |
1984年 | 321篇 |
1983年 | 252篇 |
1982年 | 248篇 |
1981年 | 235篇 |
1980年 | 207篇 |
1979年 | 253篇 |
1978年 | 216篇 |
1977年 | 206篇 |
1976年 | 203篇 |
1975年 | 233篇 |
1974年 | 262篇 |
1973年 | 267篇 |
1972年 | 210篇 |
1968年 | 205篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Test of speech-sound discrimination are used by special educators, reading specialists and speech-language pathologists in assessing children's ability to differentiate between speech sounds occurring in standard English. Such tests are important in determining if speech-sound articulation errors are caused by difficulty in making such differentiations. However, during the past 10 years, these tests have been criticized on the basis of their reliability and validity. The purpose of this study was to examine the use of two alternative methods of assessing speech-sound discrimination with a school-aged population to determine if they elicited responses in a similar manner. 相似文献
132.
133.
H-reflex amplitudes were studied during the acquisition of a motor skill involving coordinated isometric plantarflexion at the ankle joints as subjects learned to trace a triangular pattern on an oscilloscope screen by controlling plantarflexion torque applied against load cells. Torque feedback was presented on a subject oscilloscope with the right foot controlling a vertical cursor and the left foot a horizontal cursor. Eleven subjects reached criterion performance. H-reflexes were recorded from the right soleus and timed to the initiation of soleus muscle activity to plantarflex the foot. Average time to complete one trial decreased from 9 sec. in the prelearning block to 4 sec. postlearning. No single learning strategy was evident as subjects varied widely in their levels of H-reflex amplitude, but during postlearning, H-reflex amplitude became consistent within subjects as tracing performance became faster and accurate. 相似文献
134.
135.
J Allik E N Dzhafarov A J Houtsma J Ross N J Versfeld 《Perception & psychophysics》1989,46(6):513-527
Perception of global pitch motion was studied through psychoacoustic experiments with random chord sequences. Chords contained either six or eight (fixed) tone elements, being sinusoidal, sawtooth-like, or Shepard tones, which were either on or off according to a probability controlled by the experimenter. Sequences of 2, 4, 5, or 8 chords were used. Identification by subjects of the perceived direction of overall pitch motion (up or down) was found to be well accounted for by a model in which the ultimate pitch motion percept is given by a sum of contributions from selected element transitions--that is, transitions between adjoining tone elements in successive time frames only. In its simplest form, this dipole contribution model has only one free parameter, the perceptual noise for an element transition, which was estimated for various acoustic tone representations and chord arrangements. Results of two experiments, which were carried out independently in two different laboratories, are reported. 相似文献
136.
The incidence of secondary enuresis in 16 institutionalized conduct-disordered children was examined. In contrast to a control group of 16 noninstitutionalized conduct-disordered children, the former showed significantly more enuretic behaviour. Also, enuresis began within 6 mo. of the children's separation from their families, suggesting this problem is very likely related to the emotional trauma surrounding the change in living conditions. However, the small number of subjects limits further interpretation of the findings. 相似文献
137.
H N Levinson 《Perceptual and motor skills》1989,68(2):471-484
As prior studies indicated abnormal cerebellar-vestibular-based sensorimotor mechanisms and neurological and ENG diagnostic parameters in anxiety disorders and because ocular fixation and sequential scanning are cerebellar-vestibular-modulated, it appeared reasonable to measure these and related ocular functions in matched samples of anxiety-disordered and control subjects. In this study, the optokinetically-determined fixation, sequential scanning, and perceptual span capacities obtained by means of a newly revised blurring-speed method were significantly lower or impaired in 70 anxiety-disordered patients vs 70 controls. Such data supported further the hypothesis that there may be cerebellar-vestibular predispositions to anxiety disorders and the optokinetically-based tracking method may prove useful in separating a diverse array of CV-determined or related anxiety symptoms from those of other origins. However, independent validation as well as additional studies of anxiety disorders using larger samples vs random or "normal" controls are required before conclusions are justified. 相似文献
138.
Irvin Sam Schonfeld David Shaffer Joseph E. Barmack 《Journal of abnormal child psychology》1989,17(6):575-596
A group of 115 black male adolescents drawn from a clinically unselected birth cohort, half of whom were known to have had neurological soft signs at age 7, were examined at age 17 to determine the relation between soft signs and performance on standard tests of school achievement and sustained attention. Three signs measured at age 17-dysgraphesthesia, difficulties with rapid alternating movements (dysdiadochokinesis), and motor slowness—were related to lower concurrent and past IQ and to impaired performance on laboratory and paper-and-pencil measures of sustained attention. The relation between signs and the attentional measures remained significant after IQ was statistically controlled. The three age 17 soft signs as well as age 7 signs were related to impaired performance on standardized tests (age 17) of school achievement. Most of the relation between signs and school achievement could be accounted for by the variance signs shared with sustained attention. One sign, mirror movements, was unrelated to all other attentional and cognitive measures.The study was supported by center grant MH 306906 and research training grant 5 T32 MH 13043-13 from the National Institute of Mental Health, as well as by the City College and the City University Computing Centers. We thank Lillian Belmont and two reviewers for their critical comments on an earlier version of the paper. We dedicate this paper to the memory of Joseph Barmack. 相似文献
139.
Stark Lori J. Spirito Anthony Williams Connie A. Guevremont David C. 《Journal of abnormal child psychology》1989,17(2):203-212
This study investigated problems commonly experienced by adolescents and the strategies they use to cope with these events. Coping strategies were examined across the subjects' omotional state and their evaluation of the problem. In general, adolescents reported four common Stressors that were similar across age groups and gender. However, males differed from females in the frequency of these problems. Further, while the Stressors were similar, the frequency with which the coping strategies were employed and the efficacy ascribed to them differed across sex and across problem type. These findings are discussed in terms of the stress and coping literature with adults and the implications for clinical assessment and treatment of adolescents. 相似文献
140.
A model of telescoping is proposed that assumes no systematic errors in dating. Rather, the overestimation of recent occurrences of events is based on the combination of three factors: (1) Retention is greater for recent events; (2) errors in dating, though unbiased, increase linearly with the time since the dated event; and (3) intrusions often occur from events outside the period being asked about, but such intrusions do not come from events that have not yet occurred. In Experiment 1, we found that recall for colloquia fell markedly over a 2-year interval, the magnitude of errors in psychologists' dating of the colloquia increased at a rate of .4 days per day of delay, and the direction of the dating error was toward the middle of the interval. In Experiment 2, the model used the retention function and dating errors from the first study to predict the distribution of the actual dates of colloquia recalled as being within a 5-month period. In Experiment 3, the findings of the first study were replicated with colloquia given by, instead of for, the subjects. 相似文献