首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3901篇
  免费   40篇
教育   2725篇
科学研究   320篇
各国文化   61篇
体育   365篇
综合类   2篇
文化理论   53篇
信息传播   415篇
  2022年   20篇
  2021年   37篇
  2020年   75篇
  2019年   113篇
  2018年   129篇
  2017年   119篇
  2016年   101篇
  2015年   69篇
  2014年   113篇
  2013年   886篇
  2012年   90篇
  2011年   96篇
  2010年   79篇
  2009年   80篇
  2008年   81篇
  2007年   79篇
  2006年   93篇
  2005年   81篇
  2004年   74篇
  2003年   76篇
  2002年   59篇
  2001年   50篇
  2000年   58篇
  1999年   55篇
  1998年   56篇
  1997年   47篇
  1996年   41篇
  1995年   36篇
  1994年   36篇
  1993年   41篇
  1992年   34篇
  1991年   40篇
  1990年   42篇
  1989年   43篇
  1988年   49篇
  1987年   48篇
  1986年   42篇
  1985年   36篇
  1984年   38篇
  1983年   45篇
  1982年   35篇
  1981年   23篇
  1980年   26篇
  1979年   45篇
  1978年   38篇
  1977年   30篇
  1976年   32篇
  1974年   24篇
  1973年   26篇
  1969年   19篇
排序方式: 共有3941条查询结果,搜索用时 390 毫秒
891.
In the present study, primary school children’s ability to give accurate confidence judgments (CJ) was addressed, with a special focus on uncertainty monitoring. In order to investigate the effects of memory retrieval processes on monitoring judgments, item difficulty in a vocabulary learning task (Japanese symbols) was manipulated. Moreover, as a first exploratory step to uncover fast and retrieval bound (implicit) monitoring processes that take place before explicit CJ are openly reported, fixation time allocation during recognition and monitoring was recorded with an eye-tracking device. Results revealed developmental progression in uncertainty (but not in certainty) monitoring between the age of 7 and 9 years. Differences in CJ across levels of item difficulty point to a substantial impact of retrieval processes on 9-yr-olds’ but not on 7-yr-olds’ monitoring. Eye-tracking data revealed an overall bias towards medium and high CJ, and confirmed evidence on developmental progression in monitoring skills.  相似文献   
892.
Dieser Beitrag gibt einen überblick über die rechtlichen Rahmenbedingungen bei der Musiknutzung durch Hochschulen. Aus dem Urhebergesetz ergibt sich, dass eine Universit?t nicht Urheber im Rechtssinne sein kann. Sie ist weder Werksch?pfer noch ist das Urheberrecht als solches übertragbar. Bei der Nutzung von Musikstücken durch Hochschulen müssen somit insbesondere die Verwertungsrechte des Urhebers berücksichtigt werden, die seine materiellen Interessen schützen. Bei einer Nutzung von Musik über das Internet muss zwischen Streaming- und Download-Angeboten unterschieden werden. Hier kommt der Frage erhebliche Bedeutung zu, welche Rechte des Urhebers bei einer Nutzung dieser Angebote durch die Hochschule berührt werden und ob m?glicherweise gesetzliche Schrankenbestimmungen greifen. Vor diesem Hintergrund ist auch die Frage des Rechtsverh?ltnisses zur GEMA von besonderer Relevanz.  相似文献   
893.
OBJECTIVE: Although many studies have identified associations between childhood maltreatment and later substance use and disordered eating, few have examined causal or explanatory pathways, and whether victim characteristics predict the development of one versus the other of these outcomes remains uninvestigated. Furthermore, relatively little childhood maltreatment research has examined Latino samples. To address these gaps, this study examined among Latina adolescents the effects of sexual abuse, physical/emotional abuse, neglect, disconnection from family, and parental alcohol problems on poly-substance use and disordered eating, and whether five individual characteristics explain or differentiate these outcomes. METHOD: Data from a community sample of 361 Latina adolescents were analyzed using structural equation modeling. RESULTS: Physical/emotional abuse predicted poly-substance use and weight concerns, and these associations were mediated by impaired current attachment. Disconnection from family predicted bulimic behaviors, and this association was mediated by dysphoria. One indirect path also emerged: Disconnection from family predicted low social conformity, and low social conformity predicted poly-substance use. Childhood sexual abuse did not uniquely predict any adverse outcome or individual characteristic examined. CONCLUSIONS: Dysphoria and impaired current attachment appear to play important roles in the development of substance use and disordered eating in Latina adolescents when physical/emotional abuse or disconnection from family predicts these outcomes. Dysphoria and low social conformity may differentiate the development of bulimic behaviors and poly-substance use, respectively, when family disconnection predicts these outcomes.  相似文献   
894.

Objective:

This paper examines the development and evaluation of an automatic summarization system in the domain of molecular genetics. The system is a potential component of an advanced biomedical information management application called Semantic MEDLINE and could assist librarians in developing secondary databases of genetic information extracted from the primary literature.

Methods:

An existing summarization system was modified for identifying biomedical text relevant to the genetic etiology of disease. The summarization system was evaluated on the task of identifying data describing genes associated with bladder cancer in MEDLINE citations. A gold standard was produced using records from Genetics Home Reference and Online Mendelian Inheritance in Man. Genes in text found by the system were compared to the gold standard. Recall, precision, and F-measure were calculated.

Results:

The system achieved recall of 46%, and precision of 88% (F-measure = 0.61) by taking Gene References into Function (GeneRIFs) into account.

Conclusion:

The new summarization schema for genetic etiology has potential as a component in Semantic MEDLINE to support the work of data curators.

Highlights

  • Semantic MEDLINE streamlines information retrieval by succinctly expressing the meaning of sometimes complicated text and summarizing output according to a user''s needs.
  • Semantic MEDLINE identifies genes noted in biomedical text as associated with a disease process.
  • Semantic MEDLINE can potentially simplify secondary database curation.

Implications

  • Library information retrieval services can potentially benefit from automated applications such as Semantic MEDLINE.
  • Use of such automated applications can facilitate the library''s work in interdepartmental collaborative endeavors, thus reinforcing the library''s core value in its parent institution.
  相似文献   
895.
The aim of the present study was to develop and cross-validate anthropometrical prediction equations for segmental lean tissue mass (SLM). One hundred and seventeen young healthy Caucasians (67 men and 50 women; mean age: 31.9 ± 10.0 years; Body Mass Index: 24.3 ± 3.2 kg · m(-2)) were included. Body mass (BM), stretch stature (SS), 14 circumferences (CC), 13 skinfolds (SF) and 4 bone breadths (BB) were used as anthropometric measurements. Segmental lean mass of both arms, trunk and both legs were measured by dual energy X-ray absorptiometry as the criterion method. Three prediction equations for SLM were developed as follows: arms = 40.394(BM) + 169.836(CCarm-tensed) + 399.162(CCwrist) - 85.414(SFtriceps) - 39.790(SFbiceps) - 7289.190, where Adj.R (2) = 0.97, P < 0.001, and standard error of estimate (SEE) = 355 g;trunk = 181.530(BM) + 155.037(SS) + 534.818(CCneck) + 175.638(CCchest) - 88.359(SFchest) - 147.232(SFsupraspinale) - 46522.165, where Adj.R(2) = 0.97, P < 0.001, and SEE = 1077g; and legs = 55.838(BM) + 88.356(SS) + 235.579(CCmid-thigh) + 278.595(CCcalf) + 288.984(CCankle) - 84.954(SFfront-thigh) - 53.009(SFmedial calf) - 28522.241, where Adj.R (2) = 0.96, P < 0.001, and SEE = 724 g. Cross-validation statistics showed no significant differences (P < 0.05) between observed and predicted SLM. Root mean squared errors were smallest for arms (362 g), followed by legs (820 g) and trunk (1477 g). These new prediction equations allow an accurate estimation of segmental lean mass in groups of young adults, but estimation errors of 8 to 14% can occur in certain individuals.  相似文献   
896.
Kinematic, kinetic, and electromyography data were collected from the biceps femoris, rectus femoris (RF), gluteus maximus, and erector spinae (ES) during a step and elliptical exercise at a standardized workload with no hand use. Findings depicted 95% greater ankle plantar flexion (p = .01), 29% more knee extension (p = .003), 101% higher peak knee flexor moments (p < .001) 54% greater hip extensor moments (p < .001), 268% greater anterior joint reaction force (p = .009), 37% more RF activation (p < .001), and 200 % more ES activation (p <. 001) for the elliptical motion. Sixteen percent more hip flexion (p < .001), 42% higher knee extensor moments (p < .001), and 54% greater hip flexor moments (p = .041) occurred during the step motion. Biomechanical differences between motions should be considered when planning an exercise regimen.  相似文献   
897.
Abstract Little research has examined ultra-endurance swimming performances. The 'English Channel Swim', where swimmers have to cover a distance of 32?km between England and France represents a unique long-distance, open-water, sea-swimming challenge, and each year swimmers from all over the world try to succeed in this challenge. The best times in minutes and the nationality of successful men and women swimmers were analysed from 1900 to 2010. A total of 1,533 swimmers (455 women and 1,078 men) from more than 40 countries have successfully completed the 'English Channel Swim'. Great Britain was the country most represented, with 38% of the total, followed by the United States with 20%. Swim speed has increased progressively for both sexes (P??0.05). The results suggest that the performance of women open-water ultra-distance swimmers may be similar to that of men. Further studies investigating anthropometrical and physiological characteristics of open-water ultra-swimmers are needed to compare men's and women's open-water ultra-swim performances.  相似文献   
898.
This essay analyzes the controversy that attended the prize essay question on monads proposed by the Berlin Academy of Sciences in 1746. The controversy was first touched off by an anonymous pamphlet published by the mathematician Leonhard Euler, the academy's most well known member, that attacked the doctrine of monads. It peaked with the awarding of the prize to Johann Heinrich Gottlob Justi, whose winning essay closely followed Euler's arguments. This essay discusses the controversy as one instance in a broader quarrel in the German academic community over the suitability of Christian Wolff's philosophy as the foundation for a broad range of academic disciplines, including natural philosophy. It also analyzes the controversy as displaying the central role of the periodical press in the emergent German public sphere.  相似文献   
899.
Earlier research on the role of universities in fostering entrepreneurial economic development almost exclusively covers spin-offs by faculty and staff. In contrast, we provide general evidence from the U.S. showing that the gross flow of start-ups by recently graduated students with an undergraduate degree in science or engineering is at least an order of magnitude larger than the spin-offs by their faculty, that a recent graduate is twice as likely as her Professor to start a business within three years of graduation, and that the graduates’ spin-offs are not of low quality. Three case studies illustrate how universities may stimulate science and engineering students and recent graduates to create new firms of high quality. We conclude that transforming university goals and practices toward increasing start-ups led by faculty might not be the most effective way for universities to stimulate entrepreneurial economic development.  相似文献   
900.
Theory-based model of factors affecting information overload   总被引:1,自引:0,他引:1  
As the volume of available information increases, individuals and organisations become overwhelmed by the plethora of information. This can reduce productivity and performance, hinder learning and innovation, affect decision making and well-being and cost organisations large amounts of money. This paper develops a new theory-based model of factors affecting information overload and provides a formula for calculating the extent of overload, potentially of use as a diagnostic tool supporting individual or organisational development.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号