全文获取类型
收费全文 | 674852篇 |
免费 | 81812篇 |
国内免费 | 312篇 |
专业分类
756976篇 |
出版年
2018年 | 5795篇 |
2016年 | 7687篇 |
2015年 | 10828篇 |
2014年 | 12605篇 |
2013年 | 18257篇 |
2012年 | 20271篇 |
2011年 | 20659篇 |
2010年 | 13963篇 |
2009年 | 12726篇 |
2008年 | 18174篇 |
2007年 | 18932篇 |
2006年 | 17601篇 |
2005年 | 17062篇 |
2004年 | 16773篇 |
2003年 | 16528篇 |
2002年 | 16070篇 |
2001年 | 30124篇 |
2000年 | 30344篇 |
1999年 | 24199篇 |
1998年 | 8702篇 |
1997年 | 9238篇 |
1996年 | 8763篇 |
1995年 | 8315篇 |
1994年 | 8205篇 |
1993年 | 8288篇 |
1992年 | 20731篇 |
1991年 | 20233篇 |
1990年 | 19650篇 |
1989年 | 19199篇 |
1988年 | 17726篇 |
1987年 | 17128篇 |
1986年 | 15785篇 |
1985年 | 15899篇 |
1984年 | 13259篇 |
1983年 | 11566篇 |
1982年 | 8959篇 |
1981年 | 7997篇 |
1980年 | 7699篇 |
1979年 | 12912篇 |
1978年 | 10112篇 |
1977年 | 9299篇 |
1976年 | 8693篇 |
1975年 | 9514篇 |
1974年 | 10104篇 |
1973年 | 10111篇 |
1972年 | 9195篇 |
1971年 | 8537篇 |
1970年 | 7170篇 |
1969年 | 6952篇 |
1968年 | 6236篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
Argon laser surgery is an effective treatment for ectasias and congenital port-wine stains; however, its use in children under the age of 13 is controversial. This paper reviews 202 children under the age of 13 who underwent argon laser treatments for congenital port-wine stains, spider angiomas, epidermal nevi, and lentigines. The clinical characteristics of port-wine stains in 170 children are discussed. Good to excellent results (moderate to complete clearing) in port-wine stains were obtained in 60 percent of patients and seemed to correlate best with lack of blanchability on pressure. Hypertrophic scarring was seen in only 7 children, all of whom had undressed wounds; no significant scarring has been seen in any subsequent child who had maintained a dressed wound postoperatively. 相似文献
63.
64.
65.
66.
67.
68.
69.
SSU1 encodes a plasma membrane protein with a central role in a network of proteins conferring sulfite tolerance in Saccharomyces cerevisiae. 下载免费PDF全文
The Saccharomyces cerevisiae SSU1 gene was isolated based on its ability to complement a mutation causing sensitivity to sulfite, a methionine intermediate. SSU1 encodes a deduced protein of 458 amino acids containing 9 or 10 membrane-spanning domains but has no significant similarity to other proteins in public databases. An Ssu1p-GEP fusion protein was localized to the plasma membrane. Multicopy suppression analysis, undertaken to explore relationships among genes previously implicated in sulfite metabolism, suggests a regulatory pathway in which SSU1 acts downstream of FZF1 and SSU3, which in turn act downstream of GRR1. 相似文献
70.
Z Zhong A Toukdarian D Helinski V Knauf S Sykes J E Wilkinson C O'Bryne T Shea C DeLoughery R Caspi 《Applied and environmental microbiology》2001,67(12):5771-5779
An agar-degrading marine bacterium identified as a Microscilla species was isolated from coastal California marine sediment. This organism harbored a single 101-kb circular DNA plasmid designated pSD15. The complete nucleotide sequence of pSD15 was obtained, and sequence analysis indicated a number of genes putatively encoding a variety of enzymes involved in polysaccharide utilization. The most striking feature was the occurrence of five putative agarase genes. Loss of the plasmid, which occurred at a surprisingly high frequency, was associated with loss of agarase activity, supporting the sequence analysis results. 相似文献