全文获取类型
收费全文 | 28911篇 |
免费 | 378篇 |
国内免费 | 472篇 |
专业分类
教育 | 19159篇 |
科学研究 | 4365篇 |
各国文化 | 39篇 |
体育 | 1815篇 |
综合类 | 1079篇 |
文化理论 | 464篇 |
信息传播 | 2840篇 |
出版年
2024年 | 5篇 |
2023年 | 35篇 |
2022年 | 261篇 |
2021年 | 567篇 |
2020年 | 415篇 |
2019年 | 243篇 |
2018年 | 2363篇 |
2017年 | 2309篇 |
2016年 | 1768篇 |
2015年 | 753篇 |
2014年 | 1005篇 |
2013年 | 1200篇 |
2012年 | 1574篇 |
2011年 | 2135篇 |
2010年 | 2142篇 |
2009年 | 1646篇 |
2008年 | 1782篇 |
2007年 | 2391篇 |
2006年 | 1283篇 |
2005年 | 1420篇 |
2004年 | 1007篇 |
2003年 | 939篇 |
2002年 | 735篇 |
2001年 | 541篇 |
2000年 | 378篇 |
1999年 | 232篇 |
1998年 | 156篇 |
1997年 | 119篇 |
1996年 | 95篇 |
1995年 | 37篇 |
1994年 | 34篇 |
1993年 | 46篇 |
1992年 | 39篇 |
1991年 | 28篇 |
1990年 | 19篇 |
1989年 | 16篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 8篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1973年 | 2篇 |
1957年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
221.
222.
223.
Shoudong Wang Shulin Liu Jie Wang Kengo Yokosho Bin Zhou Ya-Chi Yu Zhi Liu Wolf B Frommer Jian Feng Ma Li-Qing Chen Yuefeng Guan Huixia Shou Zhixi Tian 《国家科学评论(英文版)》2020,7(11):1776
Soybean accounts for more than half of the global production of oilseed and more than a quarter of the protein used globally for human food and animal feed. Soybean domestication involved parallel increases in seed size and oil content, and a concomitant decrease in protein content. However, science has not yet discovered whether these effects were due to selective pressure on a single gene or multiple genes. Here, re-sequencing data from >800 genotypes revealed a strong selection during soybean domestication on GmSWEET10a. The selection of GmSWEET10a conferred simultaneous increases in soybean-seed size and oil content as well as a reduction in the protein content. The result was validated using both near-isogenic lines carrying substitution of haplotype chromosomal segments and transgenic soybeans. Moreover, GmSWEET10b was found to be functionally redundant with its homologue GmSWEET10a and to be undergoing selection in current breeding, leading the the elite allele GmSWEET10b, a potential target for present-day soybean breeding. Both GmSWEET10a and GmSWEET10b were shown to transport sucrose and hexose, contributing to sugar allocation from seed coat to embryo, which consequently determines oil and protein contents and seed size in soybean. We conclude that past selection of optimal GmSWEET10a alleles drove the initial domestication of multiple soybean-seed traits and that targeted selection of the elite allele GmSWEET10b may further improve the yield and seed quality of modern soybean cultivars. 相似文献
224.
225.
Haicheng Li Yinji Ma Ziwei Liang Zhouheng Wang Yu Cao Yuan Xu Hua Zhou Bingwei Lu Ying Chen Zhiyuan Han Shisheng Cai Xue Feng 《国家科学评论(英文版)》2020,7(5):849
According to the statistics of the World Health Organization, an estimated 17.9 million people die from cardiovascular diseases each year, representing 31% of all global deaths. Continuous non-invasive arterial pressure (CNAP) is essential for the management of cardiovascular diseases. However, it is difficult to achieve long-term CNAP monitoring with the daily use of current devices due to irritation of the skin as well as the lack of motion artifacts suppression. Here, we report a high-performance skin-like optoelectronic system integrated with ultra-thin flexible circuits to monitor CNAP. We introduce a theoretical model via the virtual work principle for predicting the precise blood pressure and suppressing motion artifacts, and propose optical difference in the frequency domain for stable optical measurements in terms of skin-like devices. We compare the results with the blood pressure acquired by invasive (intra-arterial) blood pressure monitoring for >1500 min in total on 44 subjects in an intensive care unit. The maximum absolute errors of diastolic and systolic blood pressure were ±7/±10 mm Hg, respectively, in immobilized, and ±10/±14 mm Hg, respectively, in walking scenarios. These strategies provide advanced blood pressure monitoring techniques, which would directly address an unmet clinical need or daily use for a highly vulnerable population. 相似文献
226.
Jin Woo Lee Anastasia Ostrowski Aileen Huang-Saad Colleen M. Seifert 《European Journal of Engineering Education》2019,44(3):360-378
ABSTRACTWith increasing demand for improved medical equipment and healthcare, next-generation biomedical engineers need strong design skills. Equipping biomedical engineering students with tools for idea generation and development can increase student design success. Design Heuristics are an ideation tool developed through empirical studies of product designs. While identified in the mechanical engineering space, Design Heuristics may be applicable in biomedical engineering design. In our study, we implemented a Design Heuristics session during upper-level undergraduate and first-year graduate biomedical engineering design courses. We examined the applicability of Design Heuristics within individual and team concept generation contexts. The findings demonstrated that biomedical engineering students were able to use Design Heuristics to generate multiple concepts, and that initial concepts produced using Design Heuristics were carried over into final team design. The results support the applicability of Design Heuristics to student idea generation in biomedical engineering design. 相似文献
227.
文宇 《佳木斯教育学院学报》2014,(6):388+390
从介绍的角度审视现成口语测试量表设计的主要种类和特点;对比量表设计的优劣;探讨合适的设计方法和可行性。 相似文献
228.
兰玉 《当代教育理论与实践》2018,(1):132-137
针对英语专业学生思辨能力薄弱、在英语写作中无法进行有效反驳的问题,教师可以从对立面观点或证据的目的、暗示和结果等八个角度和真实性、普适性等四个标准设置问题,引导学生讨论和思考、最终有效反驳.实践证明,从以上两个维度实施提问法能有效提高学生英语写作反驳的能力. 相似文献
229.
As China is getting more and more attention and Chinese culture is marching to the world, there come many internet videos on how foreigners think about China. By analyzing two videos"Chinese in foreigners’ eyes"and"China, How is it", I am going to talk about the most impressive culture mentioned by foreigners in these videos with further discussion. And only when we deeply understand our culture, not just see it by its out layer, can we explain our culture to the world effectively. In the first part, I will talk about the most impressive Chinese culture in foreigners’ eyes, and in the second part I will talk about some effective and objective ways to show what China is about. 相似文献
230.
Donghui Zhang 《Frontiers of Education in China》2018,13(3):448-450