全文获取类型
收费全文 | 165829篇 |
免费 | 7656篇 |
国内免费 | 155篇 |
出版年
2021年 | 1491篇 |
2020年 | 2782篇 |
2019年 | 3432篇 |
2018年 | 3429篇 |
2017年 | 3868篇 |
2016年 | 4550篇 |
2015年 | 3908篇 |
2014年 | 4789篇 |
2013年 | 23379篇 |
2012年 | 4323篇 |
2011年 | 3376篇 |
2010年 | 3762篇 |
2009年 | 4704篇 |
2008年 | 3566篇 |
2007年 | 3071篇 |
2006年 | 3769篇 |
2005年 | 3749篇 |
2004年 | 3270篇 |
2003年 | 2910篇 |
2002年 | 2713篇 |
2001年 | 3140篇 |
2000年 | 3004篇 |
1999年 | 3009篇 |
1998年 | 2794篇 |
1997年 | 2644篇 |
1996年 | 2557篇 |
1995年 | 2399篇 |
1994年 | 2358篇 |
1993年 | 2323篇 |
1992年 | 2462篇 |
1991年 | 2304篇 |
1990年 | 2162篇 |
1989年 | 2105篇 |
1988年 | 2075篇 |
1987年 | 2098篇 |
1986年 | 2085篇 |
1985年 | 2284篇 |
1984年 | 2417篇 |
1983年 | 2229篇 |
1982年 | 2331篇 |
1981年 | 2302篇 |
1980年 | 2134篇 |
1979年 | 2046篇 |
1978年 | 2113篇 |
1977年 | 2094篇 |
1976年 | 1875篇 |
1975年 | 1890篇 |
1974年 | 1949篇 |
1973年 | 1756篇 |
1972年 | 1406篇 |
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
891.
Variation of amplitude envelope at stimulus onset has been considered to be of primary importance for distinguishing voiceless affricates from fricatives (e.g., [symbol: see text]). In earlier perceptual experiments, however, variation in amplitude rise time was confounded with variation in frication duration. In two experiments, these variables were independently manipulated, and their individual and combined effects for perception of magnitude of [symbol: see text] were examined. Variation in amplitude rise time alone was not sufficient to signal the voiceless affricate/fricative contrast in these experiments, but variation in frication duration alone was sufficient. 相似文献
892.
This investigation was conducted to examine whether older adults would improve their performance when given statements intended to make them feel important to a research study as well as statements concerning their over-all well-being. Women (n = 14) and men (n = 15) with mean ages of 76.0 yr. and 75.1 yr., respectively, were randomly assigned into a control group, a positive reinforcement group, and a group given statements of personal importance. Dependent measures on a rotary pursuit task, screw-and-nut assembly task, and an interest questionnaire were obtained during three separate visits. Data were analyzed with a 3 x 3 (Groups x Days) analysis of variance. While no significant group effects were found on any measure, a significant main effect was obtained for days, indicative of learning. 相似文献
893.
The purpose of this study was to investigate differences in function of the tactile sensory system between groups of normal-speaking children and children with articulation problems. This task was accomplished by studying possible tactile threshold shifts occurring during magnitude-estimation scaling of vibratory stimuli presented to the dorsal surface of the tongue. 10 normal-speaking children (M age = 7.8 yr.) and 9 children with articulation problems (M age = 7.5 yr.) participated. The normal-speaking children and articulatory defective children performed differently on the magnitude-estimation scaling task in which threshold was allowed to return to baseline after each stimulus presentation. These two groups of children also showed dissimilar threshold shifts for the suprathreshold intensities employed in the magnitude-estimation scaling. 相似文献
894.
The Profile of Mood States was printed on four different colors of paper (yellow, red, green, blue) and white to test whether the color of paper would influence mood state scores of 246 college students. Univariate analyses of variance identified color effects only on the Fatigue scale. 相似文献
895.
This paper suggests a method to supplant missing categorical data by reasonable replacements. These replacements will maximize the consistency of the completed data as measured by Guttman's squared correlation ratio. The text outlines a solution of the optimization problem, describes relationships with the relevant psychometric theory, and studies some properties of the method in detail. The main result is that the average correlation should be at least 0.50 before the method becomes practical. At that point, the technique gives reasonable results up to 10–15% missing data.We thank Anneke Bloemhoff of NIPG-TNO for compiling and making the Dutch Life Style Survey data available to use, and Chantal Houée and Thérèse Bardaine, IUT, Vannes, France, exchange students under the COMETT program of the EC, for computational assistance. We also thank Donald Rubin, the Editors and several anonymous reviewers for constructive suggestions. 相似文献
896.
897.
898.
Deborah G. Mayo 《Synthese》1992,90(2):233-262
I document some of the main evidence showing that E. S. Pearson rejected the key features of the behavioral-decision philosophy that became associated with the Neyman-Pearson Theory of statistics (NPT). I argue that NPT principles arose not out of behavioral aims, where the concern is solely with behaving correctly sufficiently often in some long run, but out of the epistemological aim of learning about causes of experimental results (e.g., distinguishing genuine from spurious effects). The view Pearson did hold gives a deeper understanding of NPT tests than their typical formulation as accept-reject routines, against which criticisms of NPT are really directed. The Pearsonian view that emerges suggests how NPT tests may avoid these criticisms while still retaining what is central to these methods: the control of error probabilities.A portion of this research was carried out during tenure of a National Endowment for the Humanities Summer Stipend Fellowship; I gratefully acknowledge that support. A version of this paper was presented at the 1987 meeting of the Society for Exact Philosophy. This paper benefited from discussions and communications with George Barnard and Isaac Levi. I thank Harlan Miller for helpful comments on earlier drafts. 相似文献
899.
Binary programming models are presented to generate parallel tests from an itembank. The parallel tests are created to match item for item an existing seed test and match user supplied taxonomic specifications. The taxonomic specifications may be either obtained from the seed test or from some other user requirement. An algorithm is presented along with computational results to indicate the overall efficiency of the process. Empirical findings based on an itembank for the Arithmetic Reasoning section of the Armed Services Vocational Aptitude Battery are given.The Office of Naval Research, Program in Cognitive Science, N00014-87-C-0696 partially supported the work of Douglas H. Jones. The Rutgers Research Resource Committee of the Graduate School of Management partially supported the work of Douglas H. Jones and Ing-Long Wu. A Thomas and Betts research fellowship partially supported the work of Ing-Long Wu. The Human Resources Laboratory, United States Air Force, partially supported the work of Ronald Armstrong. The authors benefited from conversations with Dr. Wayne Shore, Operational Technologies, San Antonio, Texas. The order of authors' names is alphabetical and denotes equal authorship. 相似文献
900.
30 subjects participated in a discrimination experiment learning face-letter associations under four rotation conditions (45 degrees, 90 degrees, 135 degrees, 180 degrees). Under each condition two thirds of the faces were presented twice, upright and rotated away from the vertical; the remaining faces were presented once, upright or rotated. Learning is described by a joint Markov model: For faces that are presented twice it assumes a separate association and encoding process (two-stage-model), for faces that are presented once it assumes an association process (all-or-none-model). The Markov model fits the data for all four rotation conditions. The angle of rotation does not affect learning for faces that are presented once. For faces that are presented twice it influences both the association and the encoding process. For the angles employed, the effect of rotation can be approximated linearly. The results suggest that the encoding of a rotated face differs increasingly from an upright face as a function of these angles of rotation. This confirms analogous conclusions from mental rotation experiments. 相似文献