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Rabadán M Díaz V Calderón FJ Benito PJ Peinado AB Maffulli N 《Journal of sports sciences》2011,29(9):975-982
The aim of this study was to determine which physiological variables predict excellence in middle- and long-distance runners. Forty middle-distance runners (age 23 ± 4 years, body mass 67.2 ± 5.9 kg, stature 1.80 ± 0.05 m, VO(2max) 65.9 ± 4.5 ml · kg(-1) · min(-1)) and 32 long-distance runners (age 25 ± 4 years, body mass 59.8 ± 5.1 kg, stature 1.73 ± 0.06 m, VO(2max) 71.6 ± 5.0 ml · kg(-1) · min(-1)) competing at international standard performed an incremental running test to exhaustion. Expired gas analysis was performed breath-by-breath and maximum oxygen uptake (VO(2max)) and two ventilatory thresholds (VT(1) and VT(2)) were calculated. Long-distance runners presented a higher VO(2max) than middle-distance runners when expressed relative to body mass (P < 0.001, d = 1.18, 95% CI [0.68, 1.68]). At the intensities corresponding to VT(1) and VT(2), long-distance runners showed higher values for VO(2) expressed relative to body mass or %VO(2max), speed and oxygen cost of running (P < 0.05). When oxygen uptake was adjusted for body mass, differences between groups were consistent. Logistic binary regression analysis showed that VO(2max) (expressed as l · min(-1) and ml · kg(-1) · min(-1)), VO(2VT2) (expressed as ml · kg(-0.94) · min(-1)), and speed at VT(2) (v(VT2)) categorized long-distance runners. In addition, the multivariate model correctly classified 84.7% of the athletes. Thus, VO(2max), VO(2VT2), and v(VT2) discriminate between elite middle-distance and long-distance runners. 相似文献
993.
A comparative study of baseball bat performance 总被引:2,自引:2,他引:0
Alan M. Nathan Joseph J. Crisco R. M. Greenwald D. A. Russell Lloyd V. Smith 《Sports Engineering》2011,13(4):153-162
The results of a comparative study of five aluminum and one wood baseball bats are presented. The study includes an analysis
of field data, high-speed laboratory testing, and modal analysis. It is found that field performance is strongly correlated
with the ball–bat coefficient of restitution (BBCOR) and only weakly correlated with other parameters of the bat, suggesting
that the BBCOR is the primary feature of a bat that determines its field performance. It is further found that the instantaneous
rotation axis of the bat at the moment of impact is very close to the knob of the bat and that the rotational velocity varies
inversely with the moment of inertia of the bat about the knob. A swing speed formula is derived from the field data and the
limits of its validity are discussed. The field and laboratory measurements of the collision efficiency are generally in good
agreement, as expected on theoretical grounds. Finally, the BBCOR is strongly correlated with the frequency of the lowest
hoop mode of the hollow bats, as predicted by models of the trampoline effect. 相似文献
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Bridget C. Conlogue Neyda V. Gilman Louisa M. Holmes 《Journal of the Medical Library Association》2022,110(3):294
Objective:Academics are under great pressure to publish their research, the rewards for which are well known (tenure, promotion, grant funding, professional prestige). As open access publishing gains acceptance as a publishing option, researchers may choose a “predatory publisher.” The purpose of this study is to investigate the motivations and rationale of pharmacy and nursing academics in the United States to publish in open access journals that may be considered “predatory.”Methods:A 26-item questionnaire was programmed in Qualtrics and distributed electronically to approximately 4,500 academic pharmacists and nurses, 347 of whom completed questionnaires (~8%). Pairwise correlations were performed followed by a logistic regression to evaluate statistical associations between participant characteristics and whether participants had ever paid an article processing fee (APF).Results:Participants who had published more articles, were more familiar with predatory publishing, and who were more concerned about research metrics and tenure were more likely to have published in open access journals. Moderate to high institutional research intensity has an impact on the likelihood of publishing open access. The majority of participants who acknowledged they had published in a predatory journal took no action after realizing the journal was predatory and reported no negative impact on their career for having done so.ConclusionThe results of this study provide data and insight into publication decisions made by pharmacy and nursing academics. Gaining a better understanding of who publishes in predatory journals and why can help address the problems associated with predatory publishing at the root. 相似文献
996.
Allen M. Gontz Christopher V. Maio Ekaterina K. Wagenknecht Ellen P. Berkland 《Journal of Cultural Heritage》2011,(4):451
Rainsford Island is an 11-acre island located in central Boston Harbor, Massachusetts. The proximity to the City of Boston resulted in the Island being used as a quarantine facility, poorhouse, veteran's hospital and school for wayward boys from 1737 to 1920. The Island consists of two linked topographic highs of glacial origin connected by a spit formed from reworked glacial material. The majority of the southern “high” is only slightly elevated above present-day sea level and was the site of a cemetery that serviced the quarantine facility, poorhouse and veteran's hospital. Historical research indicates that more than 1100 persons were buried on Rainsford during this time. The records for the cemetery have been lost through fire and only four sandstone posts presently mark the cemetery. Our team sought to (1) assess shoreline change on the southern portion of the Island; (2) map the boundaries of the unmarked cemetery using ground-penetrating radar and (3) determine the vulnerability of the cemetery to coastal erosion caused by long-term sea-level rise and episodic flooding. Shoreline change analysis indicates that the southern portion of the island has eroded on the north-facing beach at a rate of 0.2 m/yr while the south-facing beach has been stable. Topographic analysis of the landscape indicates that the central area of the southern portion is less than 1 m above sea level with a slightly elevated rim approximately 2 m above sea level. The ground-penetrating radar surveys indicated that the low-lying central portion exhibited evidence for burials. The results indicate that the cemetery is vulnerable to erosion and coastal flooding. A storm with a coastal storm surge of approximately 1 m will result in flooding of the cemetery. The northern edge of the cemetery is extremely vulnerable to erosion and the first mapped burial on the northern side will be impacted in approximately 10 years. The southern edge of the cemetery is protected by horizontal and vertical accretion. As a result, conservation resources should be concentrated on the northern edge of the cemetery. 相似文献
997.
W.V. Lyon 《Journal of The Franklin Institute》1948,246(2):159-164
The equation developed here is fundamental for an understanding of the behavior of inhomogeneous insulation, especially when the insulating material is of considerable extent in the form of continuous flat sheets, or cables, or discontinuous form as in pole-line construction. The “unit” may then be measured in terms of area in the case of sheets, and in terms of length in the case of cables. It is of basic importance in insulation research, testing, and operation. It furnishes the logical basis for the establishing of safety factors. 相似文献
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