全文获取类型
收费全文 | 7303篇 |
免费 | 120篇 |
国内免费 | 211篇 |
专业分类
教育 | 4875篇 |
科学研究 | 1280篇 |
各国文化 | 16篇 |
体育 | 578篇 |
综合类 | 550篇 |
文化理论 | 6篇 |
信息传播 | 329篇 |
出版年
2024年 | 1篇 |
2023年 | 16篇 |
2022年 | 63篇 |
2021年 | 137篇 |
2020年 | 149篇 |
2019年 | 98篇 |
2018年 | 68篇 |
2017年 | 69篇 |
2016年 | 78篇 |
2015年 | 161篇 |
2014年 | 408篇 |
2013年 | 469篇 |
2012年 | 509篇 |
2011年 | 685篇 |
2010年 | 566篇 |
2009年 | 563篇 |
2008年 | 578篇 |
2007年 | 569篇 |
2006年 | 519篇 |
2005年 | 423篇 |
2004年 | 338篇 |
2003年 | 289篇 |
2002年 | 234篇 |
2001年 | 167篇 |
2000年 | 110篇 |
1999年 | 83篇 |
1998年 | 41篇 |
1997年 | 50篇 |
1996年 | 38篇 |
1995年 | 23篇 |
1994年 | 28篇 |
1993年 | 26篇 |
1992年 | 19篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有7634条查询结果,搜索用时 15 毫秒
211.
Trevor N. Simper Cecile Morris Anthony Lynn Ciara O'Hagan Karen Kilner 《运动与健康科学(英文)》2020,9(6):645-650
BackgroundOne-hour postprandial hyperglycemia is associated with increased risk of type 2 diabetes and cardiovascular disease. Physical activity (PA) has short-term beneficial effects on post-meal glucose response. This study compared the oral glucose tolerance test results of 3 groups of people with habitually different levels of PA.MethodsThirty-one adults without diabetes (age 25.9 ± 6.6 years; body mass index 23.8 ± 3.8 kg/m2; mean ± SD) were recruited and divided into 3 groups based on self-reported PA volume and intensity: low activity < 30 min/day of moderate-intensity activity (n = 11), moderately active ≥ 30 min/day of moderate-intensity PA (n = 10), and very active ≥ 60 min/day of PA at high intensity (n = 10). Participants completed an oral glucose tolerance test (50 g glucose) with capillary blood samples obtained at baseline, 15 min, 30 min, 45 min, 60 min, 90 min, and 120 min post-ingestion.ResultsThere were no significant differences between groups for age or body fat percentage or glycated hemoglobin (p > 0.05). The groups were significantly different in terms of baseline glucose level (p = 0.003) and, marginally, for gender (p = 0.053) and BMI (p = 0.050). There was a statistically significant effect of PA on the 1-h postprandial glucose results (p = 0.029), with differences between very active and low activity groups (p = 0.008) but not between the moderately active and low activity groups (p = 0.360), even when baseline glucose level and gender differences were accounted for. For incremental area under the curve there was no significant effect of activity group once gender and body fat percentage had been accounted for (p = 0.401). Those in the low activity group took 15 min longer to reach peak glucose level than those in the very active group (p = 0.012).ConclusionThe results suggest that high levels of PA have a beneficial effect on postprandial blood glucose profiles when compared to low and moderate levels of activity. 相似文献
212.
钴酸镍纳米材料具有良好的电催化氧析出反应(Oxygen Evolution Reaction,OER)活性,是一种很有发展潜力的非贵金属电催化材料。文章以碳纤维纸为基底,采用水热合成的方法对纳米结构钴酸镍的生长进行了系统的研究,分别考察了生长温度、前驱体浓度和配比、生长时间对产物的形貌、尺寸、物相结构、OER电化学性能的影响,通过对比分析后发现在生长温度100℃、生长时间5h、镍钴比为2:1时所获得的多孔片状钴酸镍纳米结构具有最佳的OER特性。 相似文献
213.
在应急决策过程中,决策信息通常具有犹豫性、模糊性和非对称性,且决策者呈现出直观、快速的语言决策偏好。提出一种基于模糊语言TOPSIS的应急决策方法,使用犹豫模糊语言术语集和二元语义表达式对高度不确定环境下的语言进行处理,提高对犹豫模糊语言信息的提取能力,生成易于理解的语言评估结果,从而辅助决策者进行快速、准确的决策判断。案例证实该方法的可行性与有效性,为解决应急决策问题提供了一种新方法。 相似文献
214.
ONP脱墨浆往往需要进一步漂白。对5种用不同脱墨剂处理的ONP脱墨浆进行了H2O2漂白实验,结果表明不同脱墨剂处理的ONP白度增加幅度不相同,各脱墨浆的可漂性并不相同。实际使用ONP脱墨浆时需考虑其漂后白度增幅潜力。 相似文献
215.
Sagar Dholariya Deepak N. Parchwani Ragini Singh Madhuri Radadiya C. D. S. Katoch 《Indian journal of clinical biochemistry : IJCB》2022,37(2):131
The coronavirus disease 2019 is a highly contagious viral infection caused by SARS-CoV-2 virus, member of coronaviridae family. It causes life threatening complications due to complexity and rapid onset course of the disease. Early identification of high-risk patients who require close monitoring and aggressive treatment remains challengeable till date. Novel biomarkers which help to identify high risk patients at the early stage is high priority. Objective of this review to find utility of P-SEP, sTREM-1 and suPAR for diagnosis, risk stratification and prognosis of SARS-CoV-2 infected cases. Soluble receptors like, P-SEP, sTREM-1 and suPAR have been involved in immune regulation in SARS-CoV-2 infection and elevate more in severe cases. A comprehensive research of databases like PubMed, EMBASE, CNKI and Web of Science was performed for relevant studies. A total of nine out of fifteen research literature in initial screening were included for this review. Interestingly all studies have reported high levels of P-SEP, sTREM-1 and suPAR in SARS-CoV-2 infected cases and the biomarkers positively correlated with severity of infection. This implies that P-SEP, sTREM-1 and suPAR can be implemented as surrogate marker in blood profile for early diagnosis, risk stratification and prognosis in SARS-CoV-2 for better management in Indian population at the current situation. 相似文献
216.
217.
基于系统观念的大学评价要贯彻以人为本的理念,其根本目标是引导大学更好地落实“立德树人”根本任务,直接目标是激发人的动力与活力。基于系统观念的大学评价要处理好“局”与“整”的关系“、办”与“评”的关系“、破”与“立”的关系“、内”与“外”的关系。基于系统观念的大学评价要树立整体观、协调观、全局观、战略观。上海理工大学进行了有益的实践探索,为基于系统观念的大学评价提供了样本和借鉴。 相似文献
218.
改革开放以来,中国经历了由东部率先发展到区域协调发展的区域战略调整,中国经济空间格局发生较大改变.探究CO2排放量对经济空间格局演变的响应,对中国尽早实现CO2排放达峰目标、确保可持续发展具有重要意义.本文在刻画1985-2017年中国经济空间格局演变特征的基础上,基于LMDI因素分解方法分析了中国CO2排放的驱动因素... 相似文献
219.
Masahiro Horiuchi Yoko Handa-Kirihara Daijiro Abe Yoshiyuki Fukuoka 《Journal of sports sciences》2019,37(14):1638-1647
We investigated combined effects of ambient temperature (23°C or 13°C) and fraction of inspired oxygen (21%O2 or 13%O2) on energy cost of walking (Cw: J·kg?1·km?1) and economical speed (ES). Eighteen healthy young adults (11 males, seven females) walked at seven speeds from 0.67 to 1.67 m s?1 (four min per stage). Environmental conditions were set; thermoneutral (N: 23°C) with normoxia (N: 21%O2) = NN; 23°C (N) with hypoxia (H: 13%O2) = NH; cool (C: 13°C) with 21%O2 (N) = CN, and 13°C (C) with 13%O2 (H) = CH. Muscle deoxygenation (HHb) and tissue O2 saturation (StO2) were measured at tibialis anterior. We found a significantly slower ES in NH (1.289 ± 0.091 m s?1) and CH (1.275 ± 0.099 m s?1) than in NN (1.334 ± 0.112 m s?1) and CN (1.332 ± 0.104 m s?1). Changes in HHb and StO2 were related to the ES. These results suggested that the combined effects (exposure to hypoxia and cool) is nearly equal to exposure to hypoxia and cool individually. Specifically, acute moderate hypoxia slowed the ES by approx. 4%, but acute cool environment did not affect the ES. Further, HHb and StO2 may partly account for an individual ES. 相似文献
220.
Lei Shuai Gongxun Zhong Quan Yuan Zhiyuan Wen Chong Wang Xijun He Renqiang Liu Jinliang Wang Qinjian Zhao Yuxiu Liu Ningning Huo Junhua Deng Jingjing Bai Hongchao Wu Yuntao Guan Jianzhong Shi Kegong Tian Ningshao Xia Hualan Chen Zhigao Bu 《国家科学评论(英文版)》2021,8(3):16-23
Minks are raised in many countries and have transmitted severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to humans. However, the biologic properties of SARS-CoV-2 in minks are largely unknown. Here, we investigated and found that SARS-CoV-2 replicates efficiently in both the upper and lower respiratory tracts, and transmits efficiently in minks via respiratory droplets; pulmonary lesions caused by SARS-CoV-2 in minks are similar to those seen in humans with COVID-19. We further found that a spike protein-based subunit vaccine largely prevented SARS-CoV-2 replication and lung damage caused by SARS-CoV-2 infection in minks. Our study indicates that minks are a useful animal model for evaluating the efficacy of drugs or vaccines against COVID-19 and that vaccination is a potential strategy to prevent minks from transmitting SARS-CoV-2. 相似文献