全文获取类型
收费全文 | 26890篇 |
免费 | 178篇 |
国内免费 | 12篇 |
专业分类
教育 | 19428篇 |
科学研究 | 2693篇 |
各国文化 | 422篇 |
体育 | 1510篇 |
综合类 | 8篇 |
文化理论 | 538篇 |
信息传播 | 2481篇 |
出版年
2021年 | 154篇 |
2020年 | 272篇 |
2019年 | 374篇 |
2018年 | 2583篇 |
2017年 | 2568篇 |
2016年 | 2029篇 |
2015年 | 419篇 |
2014年 | 469篇 |
2013年 | 2956篇 |
2012年 | 594篇 |
2011年 | 1130篇 |
2010年 | 1171篇 |
2009年 | 745篇 |
2008年 | 1049篇 |
2007年 | 1545篇 |
2006年 | 386篇 |
2005年 | 702篇 |
2004年 | 762篇 |
2003年 | 615篇 |
2002年 | 370篇 |
2001年 | 260篇 |
2000年 | 299篇 |
1999年 | 223篇 |
1998年 | 149篇 |
1997年 | 182篇 |
1996年 | 160篇 |
1995年 | 123篇 |
1994年 | 140篇 |
1993年 | 143篇 |
1992年 | 209篇 |
1991年 | 213篇 |
1990年 | 209篇 |
1989年 | 205篇 |
1988年 | 179篇 |
1987年 | 161篇 |
1986年 | 168篇 |
1985年 | 216篇 |
1984年 | 182篇 |
1983年 | 175篇 |
1982年 | 146篇 |
1981年 | 118篇 |
1980年 | 129篇 |
1979年 | 185篇 |
1978年 | 135篇 |
1977年 | 116篇 |
1976年 | 104篇 |
1975年 | 94篇 |
1974年 | 100篇 |
1973年 | 90篇 |
1971年 | 82篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
The shortage of qualified managers to assign to overseas positions has necessitated rethinking of the viable candidates pools. A relatively new group of global managers have emerged, inpatriate managers. These are foreign nationals and third-country nationals who are relocated to the organization's domestic headquarters to serve as a “linking-pin” to the global marketplace. This paper examines challenges to effectively incorporating these inpatriate managers into the domestic organization. The various issues with inpatriate manager adjustment to the domestic macro and organizational culture are examined. In addition, the necessary social support in work and non-work contexts is discussed. 相似文献
72.
The purpose of this study was to examine if steps/day taken by middle school students varied based on aerobic fitness classification. Middle school students (N = 223; 112 girls, 111 boys) were assigned to three aerobic fitness categories (HIGH, MOD, LOW) based on results of the FlTNESSGRAM PACER test. Four weekdays of pedometer monitoring determined activity levels (steps/day). Boys accumulated significantly more steps/day than girls, 11,589 +/- 3,270 and 10,232 +/- 2,517 steps/day, respectively; F(1,219) = 16.0, p < .001, eta2 = .055. There were no differences in steps/day between grades. HIGH fit participants accumulated significantly more steps/day, F(2, 217) = 12.2, p < .101, eta2 = .101, than moderately fit and low fit participants (approximately 1,491 and ; 2,867 steps/day, respectively). Middle school students who participated in sports in addition to physical education (PE) accumulated significantly more steps/day (approximately 980 steps/day) than those participating in PE only, F(1, 219) = 10.0, p < .01, eta2 = .044. Although the relationship between physical activity and aerobic fitness was moderate (0.35; p < .01), these data demonstrated significant differences in accumulated steps/day among youth of varying aerobic fitness levels. Whether improved fitness levels were the result of additional activity or the cause of it remains to be determined. Regardless, the fittest middle school students were also the most active and accumulated a significant amount of steps/day through organized extracurricular physical activities. 相似文献
73.
Effects of light refraction on the accuracy of camera calibration and reconstruction in underwater motion analysis 总被引:1,自引:0,他引:1
Kwon YH Casebolt JB 《Sports biomechanics / International Society of Biomechanics in Sports》2006,5(2):315-340
One of the most serious obstacles to accurate quantification of the underwater motion of a swimmer's body is image deformation caused by refraction. Refraction occurs at the water-air interface plane (glass) owing to the density difference. Camera calibration-reconstruction algorithms commonly used in aquatic research do not have the capability to correct this refraction-induced nonlinear image deformation and produce large reconstruction errors. The aim of this paper is to provide a thorough review of: the nature of the refraction-induced image deformation and its behaviour in underwater object-space plane reconstruction; the intrinsic shortcomings of the Direct Linear Transformation (DLT) method in underwater motion analysis; experimental conditions that interact with refraction; and alternative algorithms and strategies that can be used to improve the calibration-reconstruction accuracy. Although it is impossible to remove the refraction error completely in conventional camera calibration-reconstruction methods, it is possible to improve the accuracy to some extent by manipulating experimental conditions or calibration frame characteristics. Alternative algorithms, such as the localized DLT and the double-plane method are also available for error reduction. The ultimate solution for the refraction problem is to develop underwater camera calibration and reconstruction algorithms that have the capability to correct refraction. 相似文献
74.
K.B. Datta 《Journal of The Franklin Institute》1980,309(2):103-123
75.
Michael P. Jordan 《Instructional Science》1980,9(3):221-252
Linguistic analysis of short published reports leads to the presentation of an aigorithm that depicts the problem-solving process in terms of a series of evaluative questions. The work shows how reports enable us to define in detail the various stages of problem solving, and it shows that an understanding of these various stages enables us to recognise information structures in written texts; the writing of brief reports of high-priority information on which the whole thinking process is based is thus seen as a vital part of the problem-solving process. One report is analysed in detail to demonstrate the close relationship between information structures in the text and the real-life thought'action process it describes. There is discussion of how paragraphs, sentences and signals within the sentences enable the writer to communicate the information in a conceptual array that represents the actual thought/action process it describes. Educational implications for inter-sentential coherence, discourse analysis, and writing structures, and control of research through written reports are all discussed. 相似文献
76.
The case is considered in which, during the operation of an optimal control system, the optimizer, in addition to applying his usual control, may switch structures. Necessary and sufficient conditions are derived and emphasis is placed on the special characteristics of this problem. Continuous and discrete time set-ups are considered and the separation principle is shown not to hold for the linear quadratic case in the presence of noise. 相似文献
77.
Economists and management “scientists” tend to adopt a rationalistic, “black box” approach to the treatment of technological innovation, with decisions to invest in innovation being viewed as climactic acts and with the significant impact of risk and uncertainty often being disregarded. This paper examines an alternative analytical perspective: that a least the early development of technological innovation is a process of incremental decision making where managerial responses are affected by the consequences of previous decisions and by alterations in external information. The development of the “poromeric” Porvair discussed here illustrates the considerable risks that have to be borne when undertaking radical innovation, and the nature of the uncertainties, the interdependency between them and the manner in which they persist, in this case even beyond the commercialization of the new product. 相似文献
78.
79.
80.
Walter Hahn Helmut Skowronek H. J. Butcher Hans-Martin Müller-Wolf J. C. Cairns Michael Angermaier Maureen Woodhall Ha Wun Sung Oskar Anweiler John A. Smyth Gilbert de Landsheere Gaby Venstermans Erika Voigt Anza Amen Lema David Wolsk Robert O. Berdahl 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1974,20(1):83-107