全文获取类型
收费全文 | 333篇 |
免费 | 9篇 |
专业分类
教育 | 258篇 |
科学研究 | 19篇 |
各国文化 | 1篇 |
体育 | 21篇 |
文化理论 | 7篇 |
信息传播 | 36篇 |
出版年
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 13篇 |
2017年 | 15篇 |
2016年 | 12篇 |
2015年 | 11篇 |
2014年 | 8篇 |
2013年 | 74篇 |
2012年 | 11篇 |
2011年 | 9篇 |
2010年 | 4篇 |
2009年 | 10篇 |
2008年 | 6篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2004年 | 8篇 |
2003年 | 6篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1968年 | 3篇 |
1898年 | 2篇 |
1889年 | 2篇 |
排序方式: 共有342条查询结果,搜索用时 0 毫秒
71.
Selection medium is important in sperm isolation for assisted reproductive technologies. Contrary to the naturally occurring human cervical mucus which has a high viscosity, most current practices for motility based sperm selection use a low viscosity medium. In this study, we used a microfluidic device to assess the effects of high viscosity media made with hyaluronic acid (HA) and methyl cellulose (MC) on bovine and human sperm motility and viability (sperm transferred directly from cryoprotectant). The microfluidic penetration test, viability, and motility were compared for sperm swimming in both HA and MC media with about 20cp viscosity (measured at 20 °C). Our resulted indicate that MC medium resulted in a significantly higher number of viable bovine sperm penetrating the medium as compared to HA. Furthermore, MC resulted in the selection of a sperm subpopulation with a 274% increase in sperm viability in comparison to the raw semen, while HA increased viability by only 133%. In addition to viability, bovine sperm motility parameters were significantly higher in the MC medium as compared with HA. Experiments with human sperm swimming in MC indicate that sperm swim slower and straighter at higher viscosities. In conclusion, the results indicate that in a micro-confined environment representative of the in vivo environment, MC is a preferred high viscosity medium to ensure the highest concentration of motile and viable sperm. 相似文献
72.
73.
74.
Richard Fox 《Literacy》1996,30(2):13-14
There has been a great deal of interest in the diagnosis of, and strategies for supporting struggling readers but comparatively little to help guide teachers of struggling writers. Richard Fox tries to remedy this and introduces us to a useful analysis of some of the problems which might beset young writers. He goes on to suggest possible strategies for helping these children make progress. 相似文献
75.
76.
77.
78.
79.
80.