全文获取类型
收费全文 | 4740篇 |
免费 | 54篇 |
国内免费 | 1篇 |
专业分类
教育 | 3411篇 |
科学研究 | 357篇 |
各国文化 | 76篇 |
体育 | 400篇 |
综合类 | 2篇 |
文化理论 | 55篇 |
信息传播 | 494篇 |
出版年
2022年 | 22篇 |
2021年 | 41篇 |
2020年 | 80篇 |
2019年 | 122篇 |
2018年 | 146篇 |
2017年 | 144篇 |
2016年 | 119篇 |
2015年 | 80篇 |
2014年 | 131篇 |
2013年 | 1077篇 |
2012年 | 107篇 |
2011年 | 117篇 |
2010年 | 96篇 |
2009年 | 99篇 |
2008年 | 107篇 |
2007年 | 103篇 |
2006年 | 123篇 |
2005年 | 104篇 |
2004年 | 99篇 |
2003年 | 89篇 |
2002年 | 82篇 |
2001年 | 73篇 |
2000年 | 71篇 |
1999年 | 70篇 |
1998年 | 66篇 |
1997年 | 56篇 |
1996年 | 60篇 |
1995年 | 51篇 |
1994年 | 55篇 |
1993年 | 57篇 |
1992年 | 58篇 |
1991年 | 58篇 |
1990年 | 55篇 |
1989年 | 61篇 |
1988年 | 65篇 |
1987年 | 53篇 |
1986年 | 46篇 |
1985年 | 41篇 |
1984年 | 49篇 |
1983年 | 48篇 |
1982年 | 43篇 |
1981年 | 24篇 |
1980年 | 30篇 |
1979年 | 51篇 |
1978年 | 43篇 |
1977年 | 42篇 |
1976年 | 39篇 |
1974年 | 31篇 |
1973年 | 31篇 |
1969年 | 22篇 |
排序方式: 共有4795条查询结果,搜索用时 46 毫秒
91.
92.
Thomas M. Skovholt Tabitha L. Grier Matthew R. Hanson 《Journal of Career Development》2001,27(3):167-176
Balancing self-care and other-care is often a struggle for career counselors and others in the helping professions. The process of caring is made up of a constant series of empathic attachments, active involvements, and felt separations. The ability to continually engage in the caring cycle is important for success. However, the constant need to re-create the cycle of caring can lead to counselor depletion and burnout. This article provides a developmental framework for assisting career counselors to avoid depleted caring while prolonging their professional longevity. The model of self-care includes recognizing the hazards of high touch work, such as limited resources and constant one-way caring. Also addressed are specific means of professional and personal sustenance, such as maximizing experiences of professional success and balancing personal wellness throughout one's career. 相似文献
93.
A Methylome‐Wide Association Study of Trajectories of Oppositional Defiant Behaviors and Biological Overlap With Attention Deficit Hyperactivity Disorder 下载免费PDF全文
Edward D. Barker Esther Walton Charlotte A.M. Cecil Richard Rowe Sara R. Jaffee Barbara Maughan Thomas G. O'Connor Argyris Stringaris Alan J. Meehan Wendy McArdle Caroline L. Relton Tom R. Gaunt 《Child development》2018,89(5):1839-1855
In 671 mother–child (49% male) pairs from an epidemiological birth cohort, we investigated (a) prospective associations between DNA methylation (at birth) and trajectories (ages 7–13) of oppositional defiant disorder (ODD), and the ODD subdimensions of irritable and headstrong; (b) common biological pathways, indexed by DNA methylation, between ODD trajectories and attention deficit hyperactivity disorder (ADHD); (c) genetic influence on DNA methylation; and (d) prenatal risk exposure associations. Methylome‐wide significant associations were identified for the ODD and headstrong, but not for irritable. Overlap analysis indicated biological correlates between ODD, headstrong, and ADHD. DNA methylation in ODD and headstrong was (to a degree) genetically influenced. DNA methylation associated with prenatal risk exposures of maternal anxiety (headstrong) and cigarette smoking (ODD and headstrong). 相似文献
94.
To what extent do students and teachers hold similar beliefs about excellent teaching? Do differences in beliefs have practical implications (e.g., how students rate their teachers on end-of-semester evaluation forms)? In Study 1, undergraduate students (N=414) and faculty members (N=128) responded to questionnaires assessing their perceptions of an excellent discussion leader, lecturer, or instructor. Participants judged items that contributed to a Structure composite as more characteristic of excellent lecturers than excellent discussion leaders and items that contributed to a Process composite as more characteristic of excellent discussion leaders than excellent lecturers. Results for students and teachers showed several systematic differences. In Study 2,278 students and their course teachers rated the characteristics of a hypothetical excellent lecturer. In addition, students rated the effectiveness of their individual teachers. Students’ ratings of their teachers were higher when students and teachers agreed on their perceptions of characteristics of excellent lecturers. 相似文献
95.
96.
Median based smoothing algorithms have received considerable attention in the last few years. Their properties make them sometimes superior to linear smoothers. In this paper we develop an expression for the bivariate distribution of a median- smoothed Markov chain and we illustrate one application of it by comparing the power spectra of the input and the output of a median smoother when the input is binary valued. 相似文献
97.
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
98.
In this paper, we focus on the potential innovative benefits to corporate venture capital (CVC), i.e. equity investments in entrepreneurial ventures by incumbent firms. We propose that corporate venture capital programs may be instrumental in harvesting innovations from entrepreneurial ventures and thus an important part of a firm's overall innovation strategy. We hypothesize that these programs are especially effective in weak intellectual property (IP) regimes and when the firm has sufficient absorptive capacity. We analyze a large panel of public firms over a 20-year period and find that increases in corporate venture capital investments are associated with subsequent increases in firm patenting. 相似文献
99.
Thomas B. Åstebro 《Research Policy》2005,34(9):1404-1418
Research on technological opportunity has typically focused on the impact of broad industry characteristics on R&D intensity of firms. This study complements such approaches by examining the impact of a multidimensional vector that measures technological opportunity on independent inventors’ decisions to patent and commercialize inventions. Using data from 559 inventions and controlling for demand, appropriability, and competitive conditions, we found two of four tested dimensions of technological opportunity - technical performance and technical uncertainty - to be significant and important determinants of the likelihood of commercialization. Technical feasibility appears important in affecting patenting but unimportant in affecting commercialization. Technical significance carries a negative, although insignificant, sign conditioning commercialization. 相似文献
100.
Thomas E. Gaston Francesca Ounsworth Tessa Senders Sarah Ritchie Emma Jones 《Learned Publishing》2020,33(2):154-162
Previous research has found that researchers rank journal reputation and impact factor (IF) amongst the key selection criteria when choosing where to submit. We explored the actual effect upon submission numbers of several possible factors. We retrieved 10 years of submission data from over a thousand journals, as well as data on IF, retractions, and other factors. We performed statistical analysis and identified correlations. We also undertook case study research on the 55 most significant submission decreases. We found a statistically significant correlation between changes in IF, ISI percentage ranking, and changes in submissions numbers in subsequent years. We also found a statistically significant effect on submission numbers in the year following the publication of a retraction. Our case studies identified other factors, including negative feedback on the peer review process. Our findings regarding IF confirm previous indications about the significance of IF on submissions. We explain the correlation with retractions through the concept of ‘peer review reputation’. These results indicate that editors and publishers need to focus on a journal's peer review practices, as well as a journal's IF, if they are to maintain and grow submissions. 相似文献