全文获取类型
收费全文 | 3980篇 |
免费 | 43篇 |
专业分类
教育 | 2788篇 |
科学研究 | 321篇 |
各国文化 | 59篇 |
体育 | 367篇 |
综合类 | 2篇 |
文化理论 | 52篇 |
信息传播 | 434篇 |
出版年
2023年 | 20篇 |
2022年 | 26篇 |
2021年 | 44篇 |
2020年 | 86篇 |
2019年 | 123篇 |
2018年 | 143篇 |
2017年 | 135篇 |
2016年 | 113篇 |
2015年 | 71篇 |
2014年 | 131篇 |
2013年 | 897篇 |
2012年 | 94篇 |
2011年 | 111篇 |
2010年 | 82篇 |
2009年 | 80篇 |
2008年 | 87篇 |
2007年 | 80篇 |
2006年 | 97篇 |
2005年 | 80篇 |
2004年 | 75篇 |
2003年 | 74篇 |
2002年 | 55篇 |
2001年 | 49篇 |
2000年 | 56篇 |
1999年 | 53篇 |
1998年 | 55篇 |
1997年 | 47篇 |
1996年 | 41篇 |
1995年 | 35篇 |
1994年 | 34篇 |
1993年 | 39篇 |
1992年 | 32篇 |
1991年 | 39篇 |
1990年 | 42篇 |
1989年 | 42篇 |
1988年 | 45篇 |
1987年 | 43篇 |
1986年 | 35篇 |
1985年 | 32篇 |
1984年 | 36篇 |
1983年 | 43篇 |
1982年 | 30篇 |
1981年 | 21篇 |
1980年 | 26篇 |
1979年 | 42篇 |
1978年 | 37篇 |
1977年 | 29篇 |
1976年 | 31篇 |
1974年 | 25篇 |
1973年 | 26篇 |
排序方式: 共有4023条查询结果,搜索用时 15 毫秒
151.
Rebekka Darner Gougis Janet F. Stomberg Alicia T. O’Hare Catherine M. O’Reilly Nicholas E. Bader Thomas Meixner Cayelan C. Carey 《International Journal of Science and Mathematics Education》2017,15(6):1039-1056
The concepts of randomness and variation are pervasive in science. The purpose of this study was to document how post-secondary life science students explain randomness and variation, infer relationships between their explanations, and ability to describe and identify appropriate and inappropriate variation, and determine if students can identify sources of variation. An instrument designed to test statistical concepts was administered to 282 college students from three universities, ranging from introductory non-science majors to science graduate students. Students readily distinguished between causes of variation. A naïve no-pattern concept of randomness persisted from first-year non-science majors to senior-level science majors, contributing to incorrect responses on the variation instrument. Students’ expressions of randomness were better predictors of performance on the variation instrument than their expressions of variation. It is argued that inclusion of everyday language uses of randomness in instruction can bridge the gap between vernacular and scientific uses of this term. 相似文献
152.
153.
Suneesh Kumar Pachathundikandi Earaly Thomas Varghese 《Indian journal of clinical biochemistry : IJCB》2006,21(2):114-117
Blood zinc protoporphyrin (ZPP), serum total protein (TP), and total cholesterol (TC) levels in automobile workshop workers
in relation to lead toxicity were analysed. In the present study, automobile workshop workers (healthy male workers at an
age between 28 and 35 from four major automobile workshops in Kottayam, Kerala State, India) and the control (male healthy
adults at an age between 28 and 35 residing at Aymanam, a distant village at Kottayam District, Kerala having reduced or no
chance of lead exposure) displayed significant difference in blood lead (BPb) and blood ZZP (BZPP) level. The mean value of
BPb in automobile workshop workers was 15.76±0.33 μg/dl, while in the control it was 8.20±0.15 μg/dl. In automobile workshop
workers, the mean value of BZPP was 34.2±0.62 μg/dl. The control group exhibited a mean of 11.5±0.22 μg/dl. Automobile workshop
workers exhibited significant increase in BZPP was corresponding to the increase in BPb level. The total protein levels estimated
in automobile workshop workers showed significant decrease compared to control individuals, but was within the reference range
of healthy individuals. The mean value of TP level in automobile workshop workers and control was 6.9±0.13 g/dl and 7.71±0.18
g/dl, respectively. There was no significant difference in blood haemoglobin (BHb) level among the automobile workshop workers
and control. The serum TC level in automobile workshop workers showed significant decrease compared to the control individuals,
but was with in the reference range of healthy individuals. The mean level of serum TC in automobile workshop workers was
162.00±3.44 mg/dl and the same in control was 172.86±4.32 mg/dl. The present study affirms occupational lead toxicity in automobile
workshop workers and its effect on serum protein and cholesterol levels. 相似文献
154.
155.
Natalie C. Simpson Philip G. Hancock 《Decision Sciences Journal of Innovative Education》2011,9(2):235-253
This article chronicles the coordination and better integration of existing institutional resources to support cocurricular themes embedded in the provision of a large enrollment, video‐mediated undergraduate operations management (OM) course. The name Project Cheddarfield refers to a 2008 initiative in which two professors team‐taught an OM course to over 600 undergraduates on two different continents through the repeated rapid exchange of digital video between the United States and Singapore. Simultaneously infused in this core curricular delivery were themes of global awareness and study‐abroad, including the promotion of one particular opportunity that bridged the two campuses. This action research narrative spans over 5 years of related activity leading up to the initiative, as this project is best understood as a trajectory, or the evolving result of design adapting to unfolding realities. 相似文献
156.
157.
Christopher J. McNamara Margaret Breuker Marie Helms Thomas D. Perry Ralph Mitchell 《Journal of Cultural Heritage》2004,5(4):361-364
Outdoor bronze sculptures are highly susceptible to corrosion in many environments and organic coatings are widely used for their protection. The purpose of this study was to determine the susceptibility of the commonly used coating Incralac to biodeterioration by microorganisms. A yeast was isolated from a bronze statue treated with Incralac and its ability to degrade Incralac was determined using growth curves, scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). The organism grew slowly on Incralac in liquid culture, but SEM images demonstrated its ability to adhere to Incralac coated metal. Additionally, the yeast caused a rapid drop in the low frequency impedance of Incralac coated metal that was not observed under sterile conditions, indicating that the organism accelerated deterioration of the coating. The potential for microbial growth to accelerate deterioration of Incralac should be considered when developing a maintenance strategy for the protection of outdoor metal monuments. 相似文献
158.
Elizabeth L. Eisenstein Roy Harley Lewis Jack Lindsay Thomas Weyr Charles B. Osburn Robert Egan 《Communication Booknotes Quarterly》2013,44(3):56-60
Elizabeth L. Eisenstein, The Printing Press as an Agent of Change (Cambridge and New York: Cambridge University Press, 1979---$49.50 for the two volume set) Roy Harley Lewis' Antiquarian Books: An Inisder's Account (New York: Arco, 1979---$10.00) Jack Lindsay's William Morris: His Life and Work (New York: Taplinger, 1979---$14.95) Thomas Weyr's Reaching for Paradise: The Playboy Vision of America (New York: Times Books, 1979---$12.50) Book Publishing Worldwide, A Publisher's Weekly Extra (New York: R.R. Bowker, 1979---S6.95, paper) Scholarly Communication: The Report of the National Enquiry (Baltimore: The Johns Hopkins University Press, 1979---$3.95, paper) Charles B. Osburn's Academic Research and Library Resources: Changing Patterns in America (Westport, Conn.: Greenwood Press, 1979---$18.95) Robert Egan's The Bookstore Book: A Guide to Manhattan Booksellers (New York: Avon Books, 1979---$5.95, paper) 相似文献
159.
Attentional focus effects as a function of task difficulty 总被引:1,自引:0,他引:1
160.