全文获取类型
收费全文 | 7310篇 |
免费 | 585篇 |
国内免费 | 1篇 |
出版年
2023年 | 49篇 |
2022年 | 32篇 |
2021年 | 221篇 |
2020年 | 141篇 |
2019年 | 153篇 |
2018年 | 173篇 |
2017年 | 153篇 |
2016年 | 253篇 |
2015年 | 423篇 |
2014年 | 448篇 |
2013年 | 530篇 |
2012年 | 680篇 |
2011年 | 642篇 |
2010年 | 395篇 |
2009年 | 362篇 |
2008年 | 503篇 |
2007年 | 426篇 |
2006年 | 417篇 |
2005年 | 355篇 |
2004年 | 312篇 |
2003年 | 247篇 |
2002年 | 264篇 |
2001年 | 50篇 |
2000年 | 48篇 |
1999年 | 52篇 |
1998年 | 44篇 |
1997年 | 37篇 |
1996年 | 33篇 |
1995年 | 35篇 |
1994年 | 30篇 |
1993年 | 17篇 |
1992年 | 42篇 |
1991年 | 31篇 |
1990年 | 23篇 |
1989年 | 31篇 |
1988年 | 16篇 |
1987年 | 21篇 |
1986年 | 22篇 |
1985年 | 21篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1980年 | 15篇 |
1979年 | 7篇 |
1978年 | 9篇 |
1977年 | 13篇 |
1976年 | 8篇 |
1975年 | 9篇 |
1973年 | 10篇 |
排序方式: 共有7896条查询结果,搜索用时 62 毫秒
1.
2.
3.
4.
5.
Nicolas Delaleu Heike Immervoll Janet Cornelius Roland Jonsson 《Arthritis research & therapy》2008,10(1):R22
Introduction
Sj?gren's syndrome (SS) is a systemic autoimmune disease that mainly targets the exocrine glands. The aim of this study was to investigate the involvement of 87 proteins measured in serum and 75 proteins analyzed in saliva in spontaneous experimental SS. In addition, we intended to compute a model of the immunological situation representing the overt disease stage of SS. 相似文献6.
7.
Craig R. Allen Ahjond S. Garmestani Jill A. LaBram Amanda E. Peck Luanna B. Prevost 《Biological invasions》2006,8(2):169-176
Woodlots are forest islands embedded within an urban matrix, and often represent the only natural areas remaining in suburban
areas. Woodlots represent critical conservation areas for native plants, and are important habitat for wildlife in urban areas.
Invasion by non-indigenous (NIS) plants can alter ecological structure and function, and may be especially severe in remnant
forests where NIS propagule pressure is high. Woody shrubs in the Family Berberidaceae have been well documented as invaders
of the forest–urban matrix in North America. Mahonia bealei (Berberidaceae) is a clonal shrub native to China, and is a popular ornamental in the Southeastern United States. Mahoni bealei is listed as “present” on some local and state floras, but almost nothing is known regarding its invasion potential in the
United States. We sampled 15 woodlots in Clemson, South Carolina, to assess the invasion of M. bealei and other woody non-indigenous species (NIS). M. bealei invaded 87% of the woodlots surveyed and species richness of NIS on these woodlots varied from 5 to 14. Stepwise-multiple
regression indicated that less canopy cover and older M. bealei predicted greater abundance of M. bealei , and that not all subdivisions were equally invaded (P < 0.0001; r2 = 0.88). The impact of M. bealei on native flora and fauna may be considerable, and it is likely to continue to spread in the Southeastern United States.
M. bealei should be recognized as an aggressive invader in the Southeastern United States, with the potential for negative impacts
on native flora and fauna. 相似文献
8.
9.
10.