全文获取类型
收费全文 | 22494篇 |
免费 | 348篇 |
国内免费 | 30篇 |
专业分类
教育 | 16190篇 |
科学研究 | 1986篇 |
各国文化 | 203篇 |
体育 | 1713篇 |
综合类 | 34篇 |
文化理论 | 189篇 |
信息传播 | 2557篇 |
出版年
2022年 | 133篇 |
2021年 | 229篇 |
2020年 | 363篇 |
2019年 | 491篇 |
2018年 | 699篇 |
2017年 | 772篇 |
2016年 | 716篇 |
2015年 | 429篇 |
2014年 | 576篇 |
2013年 | 4228篇 |
2012年 | 563篇 |
2011年 | 631篇 |
2010年 | 481篇 |
2009年 | 457篇 |
2008年 | 519篇 |
2007年 | 500篇 |
2006年 | 441篇 |
2005年 | 385篇 |
2004年 | 364篇 |
2003年 | 327篇 |
2002年 | 378篇 |
2001年 | 424篇 |
2000年 | 396篇 |
1999年 | 402篇 |
1998年 | 210篇 |
1997年 | 230篇 |
1996年 | 254篇 |
1995年 | 213篇 |
1994年 | 210篇 |
1993年 | 193篇 |
1992年 | 302篇 |
1991年 | 300篇 |
1990年 | 329篇 |
1989年 | 311篇 |
1988年 | 295篇 |
1987年 | 248篇 |
1986年 | 256篇 |
1985年 | 322篇 |
1984年 | 266篇 |
1983年 | 255篇 |
1982年 | 196篇 |
1981年 | 206篇 |
1980年 | 176篇 |
1979年 | 240篇 |
1978年 | 214篇 |
1977年 | 194篇 |
1976年 | 160篇 |
1975年 | 128篇 |
1974年 | 120篇 |
1973年 | 147篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
This paper explores a project funded through the National Network of Libraries of Medicine to enhance effective use of the Internet by public health professionals. The processes and outcome of an effort to develop a statewide Web site for public health professionals are described. A series of focus groups was conducted as a preliminary data-gathering tool to evaluate the information needs of the target population. Results of the focus group provided a valuable framework upon which to build a successful schema for Web site development. 相似文献
942.
Dixon LA 《Medical reference services quarterly》2002,21(2):55-64
Librarians often are responsible for instructing their patrons in the use of various databases and popular software packages. When this instruction can't be provided through face-to-face contact, Web-based tutorials can be useful tools to bridge the information gap. This article recommends Web-based tutorials for PubMed, Ovid MEDLINE, PowerPoint, and FrontPage. 相似文献
943.
Generalized Hamming Distance 总被引:4,自引:0,他引:4
Many problems in information retrieval and related fields depend on a reliable measure of the distance or similarity between objects that, most frequently, are represented as vectors. This paper considers vectors of bits. Such data structures implement entities as diverse as bitmaps that indicate the occurrences of terms and bitstrings indicating the presence of edges in images. For such applications, a popular distance measure is the Hamming distance. The value of the Hamming distance for information retrieval applications is limited by the fact that it counts only exact matches, whereas in information retrieval, corresponding bits that are close by can still be considered to be almost identical. We define a Generalized Hamming distance that extends the Hamming concept to give partial credit for near misses, and suggest a dynamic programming algorithm that permits it to be computed efficiently. We envision many uses for such a measure. In this paper we define and prove some basic properties of the Generalized Hamming distance, and illustrate its use in the area of object recognition. We evaluate our implementation in a series of experiments, using autonomous robots to test the measure's effectiveness in relating similar bitstrings. 相似文献
944.
945.
The significance of in vitro changes in immune function accompanying exercise training is unclear. To determine the effect of exercise on the response of the intact immune system to a challenge in vivo, we measured the speed and overall immunoglobulin G (IgG) response to influenza vaccination in humans engaged in different intensities of activity. Male participants (n = 21) were split into heavy and light training groups. Venous blood samples were collected 0, 2, 4, 7, 10 and 14 days after vaccination with trivalent influenza vaccine, and also 12 months after initial vaccination. Serum IgG was determined by enzyme-linked immunosorbant assay. There was a significant difference in baseline IgG between groups, but no difference in IgG concentration 14 days after vaccination. The IgG concentration remained elevated 12 months post-vaccination in the heavy training group. The results suggest a positive relationship between habitual physical activity and baseline antibody concentrations, which, in turn, affects the relative magnitude (fold or percentage increase) of the antibody response to vaccination. The training loads of the participants in this study had no effect on overall IgG measured 14 days after vaccination. 相似文献
946.
The aim of this paper is to present a motivational model of the coach-athlete relationship that describes how coaches may influence athletes' motivation. In line with cognitive evaluation theory (Deci and Ryan, 1980, 1985) and the hierarchical model of intrinsic and extrinsic motivation (Vallerand, 1997, 2000), a motivational sequence is proposed where coaches' personal orientation towards coaching, the context within which they operate, and their perceptions of their athletes' behaviour and motivation influence coaches' behaviours. Also, coaches' behaviours in the form of autonomy-supportive behaviours, provision of structure and involvement have a beneficial impact on athletes' needs for autonomy, competence and relatedness, which, in turn, nurture athletes' intrinsic motivation and self-determined types of extrinsic motivation. Here, we first review coaches' autonomy-supportive behaviours. We then describe the psychological processes through which coaching behaviours have a positive influence on athletes' intrinsic and self-determined extrinsic motivation. Finally, we identify social and personality processes that determine coaching behaviours. 相似文献
947.
Mechanisms of attentional cueing during observational learning to facilitate motor skill acquisition
We examined the effectiveness of different cueing conditions during observational learning of a soccer accuracy pass. Sixty participants (30 males, 30 females) were randomly assigned and stratified by sex into one of six groups: discovery learning, verbal instruction, video model with visual cues, video model with verbal cues, video model with visual and verbal cues, and video model only. Each participant completed eight blocks of 10 trials each, with trial blocks 1 and 2 representing the practice phase (no manipulation), trial blocks 3, 4, 5 and 6 the acquisition phase (manipulation administered) and trial blocks 7 and 8 the retention phase (24 h after acquisition, with no manipulation). Absolute error, variable error and kicking form were recorded. The results indicated that those who used video modelling with visual and verbal cues collectively displayed less error and more appropriate form across acquisition and retention trial blocks compared with other groups. Our findings suggest that verbal information in addition to visual cues enhances perceptual representation and retention of modelled activities to improve task reproduction capabilities. Future research directions are proposed with implications for both direct and indirect perception accounts of skill acquisition through observed behaviours. 相似文献
948.
The purpose of this study was to determine the influence of beliefs about gender appropriateness and conceptions of ability on perceived and actual competene and patterns of behavior during practice of the hockey wrist shot. Sixty-eight undergraduate women formed four treatment conditions based on their beliefs about gender appropriateness and conceptions of ability. Four teachers taught across the treatment conditions for a total of 16 learning groups. Data were collected through a three-part questionnaire and from audio-video taping of the entire episode to ascertain the paticipants' competency beliefs, effort, and performance. Gender appropriateness impacted the participants' perceptions of competence and actual performance in the study, while beliefs about conceptions of ability did not produce a significant difference. This study reaffirms that educators must work diligently to combat the stereotypical beliefs many hold with respect to the gender appropriateness of physical activities. 相似文献
949.
The purpose of this study was to investigate if children perceived certain sports to be masculine, feminine, or neutral. Students attending a University Laboratory school (grades K-12) were asked to fill out a survey about sports during a class period, Children in grades K-6 were given a sport (such as baseball) and asked if a boy named David would play it, if a girl named Jane would play it, or if both David and Jane would play the sport. Students in grades 7-12 were asked to name their favorite athlete or team and sport and indicate what sports they felt was best for a girl and a boy. Then they were given a list of sports and asked to indicate, using a 5-point Likert-type scale, whether they believed the sport was masculine, neutral, or feminine. Results from loglinear analyses indicated that students sex-typed certain sports, such as aerobics and football. Additionally, although some responses from students in grades 7-12 indicated that individuals should be able to play any sport they wanted, there were many gendered rsponses in terms of what sport(s) girls and boys should participate in. The results are discussed with reference to Metheny's categories of permissible sports for girls and in the framework of the gender typing of sport. 相似文献
950.
Dannecker EA Hausenblas HA Connaughton DP Lovins TR 《Research quarterly for exercise and sport》2003,74(3):236-247
The purpose of this study was to examine evidence for the validity of a stages of change measure of the Transtheoretical Model for exercise behavior. Participants were 152 university students (53.3% women, 71.6% Caucasian, M age = 19.18 years) who completed processes of change, self-efficacy, decisional balance, stages of change, and exercise behavior questionnaires as well as a maximal treadmill test. Participants in the action and maintenance stages had the highest strenuous (PC/C/P < A/M) and moderate (PC/C < A/M) self-reported exercise behavior. Those in the maintenance stage had the highest estimated aerobic fitness (PC/P < MA). The differences between the early stages (PC, C, and P) and the later stages (A and M) as described by the first function were primarily due to the behavioral process of change. The differences between the extreme stages (PC and M) and the middle stages (C, P, and A) were due to the experiential processes of change and the pros of decisional balance. The hypothesized patterns of stage differences were partially supported. Failure to obtain full support may have been due to methodological issues or inherent difficulties in detecting evidence for the validity of stages of change measures. 相似文献