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   194322篇
  免费   8430篇
  国内免费   162篇
  202914篇
  2020年   2877篇
  2019年   3531篇
  2018年   3751篇
  2017年   4190篇
  2016年   4815篇
  2015年   4006篇
  2014年   4901篇
  2013年   23900篇
  2012年   5207篇
  2011年   4417篇
  2010年   4213篇
  2009年   5006篇
  2008年   4622篇
  2007年   4166篇
  2006年   4618篇
  2005年   4518篇
  2004年   4041篇
  2003年   3671篇
  2002年   3459篇
  2001年   3938篇
  2000年   3818篇
  1999年   3588篇
  1998年   2939篇
  1997年   2754篇
  1996年   2669篇
  1995年   2502篇
  1994年   2469篇
  1993年   2424篇
  1992年   3039篇
  1991年   2886篇
  1990年   2760篇
  1989年   2617篇
  1988年   2591篇
  1987年   2610篇
  1986年   2588篇
  1985年   2837篇
  1984年   2841篇
  1983年   2541篇
  1982年   2492篇
  1981年   2456篇
  1980年   2274篇
  1979年   2579篇
  1978年   2369篇
  1977年   2271篇
  1976年   2140篇
  1975年   2338篇
  1974年   2502篇
  1973年   2425篇
  1972年   1927篇
  1971年   1860篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
951.
A soft contact-lens system for achieving unilateral visual stimulation in a free vision format is described. Initial testing with light transmittance and visual perimetry indicated that the lenses created artificial visual-field deficits. The efficacy of the lenses as a technique for lateralizing visual input was evaluated by examining within-subject differences in performance on two visuospatial tasks. Speed and accuracy of performance were greater with visual input directed to the right hemisphere. These data support the lens design as a useful alternative to tachistoscopic procedures and previous lens systems.  相似文献   
952.
The subtests of the Brain Age Quotient, a brief neuropsychological battery, were used to screen for cognitive impairment in a sample of 112 substance abusers. Each of the subtests was scored, using newly developed T scores corrected for age, education, and gender, for which a mean battery score of T less than 40 indicates general cognitive impairment. The chance-corrected agreement in finding cognitive dysfunction between this battery and the Average Impairment Rating T score from the Halstead-Reitan battery was adequate, kappa = .81. This result suggests that, for discerning global cognitive impairment, this relatively brief neurodiagnostic screening device may be an attractive alternative to the more time-consuming Halstead-Reitan battery.  相似文献   
953.
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   
954.
The purpose of the present study was to analyse the arousing effects of noise on sleep inertia as a function of circadian placement of a one-hour nap. In a first experiment, we measured the effects of sleep inertia in a neutral acoustic environment after a one-hour nap placed either at 0100 or 0400 on response time during a spatial memory test. In a second experiment were analysed the effects of an intense continuous noise on sleep inertia. The results showed that noise produced a total abolition of sleep inertia after an early nap (0000 to 0100). This may be due to the arousing effect of noise; however, results are less clear after a late nap 0300 to 0400 as noise seems to be ineffective. This result is discussed in terms of either a function of time-of-day effect or of prior sleep intensity. Moreover, our data suggest a possible interaction of noise with partial sleep deprivation leading to a slight deleterious effect those subjects who did not sleep at all.  相似文献   
955.
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   
956.
957.
958.
The ω-rule     
Michael Thau 《Studia Logica》1992,51(2):241-248
We prove that all proofs in -logic (a first order logic with -rule added) in which -rule is used finitely many times can be turned into proofs in which the -rule is used at most one time. Next, we prove that the word finitely above cannot be changed by the word infinitely.  相似文献   
959.
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   
960.
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   
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