全文获取类型
收费全文 | 179647篇 |
免费 | 7989篇 |
国内免费 | 157篇 |
专业分类
187793篇 |
出版年
2020年 | 2780篇 |
2019年 | 3444篇 |
2018年 | 3551篇 |
2017年 | 3999篇 |
2016年 | 4645篇 |
2015年 | 3922篇 |
2014年 | 4797篇 |
2013年 | 23431篇 |
2012年 | 4656篇 |
2011年 | 3784篇 |
2010年 | 3934篇 |
2009年 | 4787篇 |
2008年 | 3971篇 |
2007年 | 3526篇 |
2006年 | 4108篇 |
2005年 | 4073篇 |
2004年 | 3586篇 |
2003年 | 3248篇 |
2002年 | 3027篇 |
2001年 | 3475篇 |
2000年 | 3352篇 |
1999年 | 3277篇 |
1998年 | 2843篇 |
1997年 | 2686篇 |
1996年 | 2602篇 |
1995年 | 2431篇 |
1994年 | 2402篇 |
1993年 | 2349篇 |
1992年 | 2739篇 |
1991年 | 2606篇 |
1990年 | 2459篇 |
1989年 | 2363篇 |
1988年 | 2369篇 |
1987年 | 2358篇 |
1986年 | 2342篇 |
1985年 | 2535篇 |
1984年 | 2631篇 |
1983年 | 2385篇 |
1982年 | 2415篇 |
1981年 | 2368篇 |
1980年 | 2205篇 |
1979年 | 2356篇 |
1978年 | 2254篇 |
1977年 | 2187篇 |
1976年 | 2013篇 |
1975年 | 2099篇 |
1974年 | 2257篇 |
1973年 | 2151篇 |
1972年 | 1673篇 |
1971年 | 1644篇 |
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
901.
Much of what we learn from an experiment depends on what we ask of the subjects and how we ask it. Most music perception and cognition research is implemented using a single methodology. Recently, questions have been raised about the validity and generalizability of such a limited approach, particularly regarding such complicated theoretical constructs as musical tonality. We propose that a useful technique is to converge on the answer to experimental questions by applying multiple methods, in essence, simultaneously investigating the central research question as well as ancillary questions of method. Such an approach is facilitated by a computer hardware and software system that integrates experimental design, data collection, data analysis, and data dissemination, linking off-the-shelf components through standard file formats and data-exchange protocols. The list-based system, using an IBM-type PC running Windows 3.0, handles real-time natural sound sampling and playback, signal synthesis and analysis, MIDI input and output, digitized picture display, and various subject-response mechanisms. On the basis of graphical icons, the integrated system can be used to build custom experimental designs. Examples of convergent psychomusical experiments that were designed, implemented, and analyzed using the system are discussed. 相似文献
902.
Robert W. Allan 《Behavior research methods》1992,24(2):150-156
Pigeons’ pecking has long been a subject of interest in behavioral research, with the response typically being viewed as unitary. Recent experiments done with computer-controlled devices have revealed that this response is at least bipartite in character, with beak opening and response location (head transport) as its components. In addition, experimental work has demonstrated that these response components may be separately influenced and controlled by respondent and operant conditioning procedures. The detailed topographic analysis and technology that have emerged may provide a background for similar work with other behavioral systems. 相似文献
903.
Douglas B. Eamon 《Behavior research methods》1992,24(2):174-179
Modern spreadsheets are powerful and useful tools that can often replace special-purpose programs for generating data and for student analysis of simple statistical problems. The inherent flexibility of spreadsheets makes them especially convenient and extensible. Several templates for generating and analyzing data fort tests and analysis of variance are discussed. Users can specify then, \(\bar X\) , andSD of two or more groups and then execute macros that generate appropriate data. Overwriting the generated data with “real” values turns the spreadsheet into a data analysis program. Spreadsheets hold promise as valuable instructional supplements for simple designs, but they are less suitable for more complex designs, where special-purpose programs may be more appropriate. 相似文献
904.
Adrienne Y. Lee 《Behavior research methods》1992,24(2):205-212
HyperCard was used to develop a simplified tutoring system whose principles were based on a learning theory, and a genetics tutoring system was evaluated experimentally. Learning was studied by examining immediate versus delayed feedback after an error was made. Such tutoring systems aid in psychological studies of learning, because experimental variables can be easily manipulated. HyperCard provides a good vehicle for tutoring system development, since it requires no extensive programming skills. 相似文献
905.
Data often contain periodic components plus random variability. Walsh analysis reveals periodicities by fitting rectangular functions to data. It is analogous to Fourier analysis, which represents data as sine and cosine functions. For many behavioral measures, Fourier transforms can produce spurious peaks in power spectra and fail to resolve separable components. Walsh analysis is superior for strongly discontinuous data. The strengths and weaknesses of each transform are discussed, and specific algorithms are given for the newer Walsh technique. 相似文献
906.
Michael E. Mills 《Behavior research methods》1992,24(2):321-325
GRADER, a computer program that makes student test and/or course letter grade recommendations to instructors, is described. The program uses an algorithm to combine the content mastery (percentage correct) and peer comparison (“curve”) approaches to set grade cutoffs. In addition to standardizing the procedures with which letter grade cutoffs are made, GRADER may help to reduce instructor grading subjectivity and obviate tendencies toward grade inflation or deflation. 相似文献
907.
A running-wheel movement-detection method is described for use with a modified 1350 Commodore mouse and a Commodore 64, is described. The movement-detection method allows for the detection of partial revolutions and direction of movement, but requires no interface equipment. The modified running wheel is discussed as a new technique that may be useful for bridging empirical and theoretical differences between free-operant and discrete-trial runway procedures. 相似文献
908.
Changes in heart rate were examined during classical aversive conditioning before and after either left (n=10) or right stellectomy (n=8). Heart rate (HR) significantly (p<0.01) increased in response to the conditional stimulus with a further increase noted during the unconditional stimulus. After right stellectomy (RSGx) the aversive stress elicited a significantly (p<0.01) smaller increase in heart rate (peak HR change: control 66.8 +/- 6.0; RSGx 36.1 +/- 6.8 beats/min). In contrast left stellectomy did not significantly alter the heart rate conditional response. Cardioselective beta-adrenergic receptor blockade, metoprolol HCl (BB, 1.0 mg/kg, n=8), significantly (p<0.01) reduced the heart-rate conditional response (peak HR change: control 66.8 +/- 6; BB 25.1 +/- 3.8 beats/min) to the same extent as noted during RSGx. These data suggest that the heart-rate increases elicited by aversive stress are mediated in part by sympathetic nerves that originate or pass through the right stellate ganglion. The residual HR increase noted after RSGx or BB probably results from the withdrawal of cardiac parasympathetic activity. 相似文献
909.
Variation of amplitude envelope at stimulus onset has been considered to be of primary importance for distinguishing voiceless affricates from fricatives (e.g., |t∫| and |∫|). 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 |t∫| and |∫| 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
910.
Quantification of a chaotic system can be made by calculating the correlation dimension (D2) of the data that the system generates
(Packard et al., 1980). The D2 algorithm, however, requires stationarity of the generator, a feature that biological data
rarely reflect (Mayer-Kress et al., 1988). So we developed the “point correlation dimension” (PD2), an algorithm that accurately
tracks D2 in linked data of different dimensions (Carpeggiani et al., 1991). We now present a mathematical argument that,
for stationary data, individual PD2s converge to D2 and we demonstrate that the algorithm rejects contributions made by bursts
of noise. Data were obtained from the surface of the olfactory bulb of the conscious rabbit (64 electrodes, 640 Hz each, 1.3
sec epochs) before and after presentation of a novel or habituated odor. D2 could be calculated in only 1 of 10 novel-odor
trials, whereas PD2 could be calculated in all. Both algorithms indicated that a novel odor evokes a spatially uniform dimensional
increase. The PD2 uniquely exhibited the dimensional decreases that occur during inspiration and the gradients of mean dimension
present during the nonstimulated control state. These control gradients remained unchanged without odor experience, but showed
spatially specific PD2 increases following odor habituation. It is interpreted that, 1) the PD2 issensitive, accurate, and appropriate for dimensional assessment of biological data, 2) that during analysis of unfamiliar information a singleglobal process is transiently evoked in the neuropil, and 3) after experience multiplespatially specific processes tonically map the sites of learning.
Grant Support: National Institutes of Health, HL 31164 and NS27745 相似文献