全文获取类型
收费全文 | 620篇 |
免费 | 53篇 |
专业分类
673篇 |
出版年
2023年 | 4篇 |
2021年 | 10篇 |
2019年 | 4篇 |
2018年 | 5篇 |
2017年 | 9篇 |
2016年 | 13篇 |
2015年 | 24篇 |
2014年 | 23篇 |
2013年 | 31篇 |
2012年 | 44篇 |
2011年 | 32篇 |
2010年 | 30篇 |
2009年 | 16篇 |
2008年 | 50篇 |
2007年 | 53篇 |
2006年 | 43篇 |
2005年 | 38篇 |
2004年 | 23篇 |
2003年 | 24篇 |
2002年 | 28篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 7篇 |
1998年 | 12篇 |
1997年 | 10篇 |
1996年 | 3篇 |
1995年 | 8篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 11篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 9篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1973年 | 3篇 |
1972年 | 5篇 |
1968年 | 4篇 |
1967年 | 3篇 |
1965年 | 3篇 |
排序方式: 共有673条查询结果,搜索用时 0 毫秒
641.
The role of aggregation for the dissolution of diatom frustules 总被引:4,自引:0,他引:4
642.
Uta Maier-Maercker 《Trees - Structure and Function》1998,12(3):181-185
The method of image analysis was used to re-investigate previously described structural changes in spruce needles following
their exposure to ozone. The changes observed in fumigation experiments were compared with the modifications observed at a
site with a similar ozone load. Use was made in each case of needles for which the varying behavioural patterns were known
from physiological experiments. In samples with reduced ability to regulate stomatal aperture, the cell walls of the stomatal
apparatus showed a reduction in absorptive power at 280 nm. This was interpreted to be a result of delignification of the
cell walls in question due to the direct impact of ozone on the surface of the needle.
Received: 21 May 1997 / Accepted: 30 June 1997 相似文献
643.
Summary
Prestwoodia delicata (Travassos, 1946) Anderson, 1978, Heterostrongylus heterostrongylus Travassos, 1925 and Didelphostrongylus hayesi Prestwood, 1976 are redescribed on the basis of new collections of specimens from Didelphis marsupialis from North and South America. The three genera are unique to the opossum. Prestwoodia from the nasal sinuses is most similar to Troglostrongylus of Felidae. Heterostrongylus and Didelphostrongylus are similar in size and certain other features such as their six prominent lips and reduced bursae. The dorsal ray in the former, however, consists of a large, rounded lobe whereas in the latter, it is divided into two long branches. Didelphostrongylus is found under the pleura whereas Heterostrongylus is found in the bronchi. ac]19790102 相似文献
644.
Jiro Hoshino Uta Kühne Gabriele Studinger Hans Kröger 《Biochemical and biophysical research communications》1977,74(2):663-669
A single administration of a low dose of cortisone acetate (0.2 mg/100 g) into adrenalectomized rats reduces the cell-free protein synthesizing activity of isolated total liver polysomes by 60 % after 90 min. DBcAMP also inhibits markedly the protein synthesizing activity but its effect is due to an inactivation of soluble fraction. Combined administration of both drugs yields polysomes active more than twice than those of untreated control. Inhibition by the glucocorticoid was restricted only to the membrane-bound polysomes. 相似文献
645.
Summary
Aviculariella alcyona Wehr, 1931 is redescribed on the basis of specimens from the gizzard of Megaceryle a. alcyon (L.) (Alcedinidae). Numerous characters are reported for the first time. The genus is distinguished from Rusguniella and Ingliseria by the presence of triangular cordons with an inner denticulate border, a prominent cephalic vesicle behind the cordons and simple deirids. The genus also contains: A. brevis (Maplestone, 1931) of Halcyon smyrnensis in India; A. alcedonis (Yamaguti & Mitunaga, 1943) of Alcedo atthis bengalensis in Taiwan; A. collaricephala (Oschmarin, 1959) of Alcedo atthis in the U.S.S.R.; A petterae Bain & Chabaud, 1965 of Corythornis vingtsioides (Turdidae) in Madagascar and A. alii (Rasheed, 1960) n. comb. of Ceryle radis leucomelanura in India; the last-named species may be a synonym of A. brevis. The status of some of these species requires further study. ac]19790421 相似文献
646.
Background
Modern sequencing technologies allow rapid sequencing and bioinformatic analysis of genomes and metagenomes. With every new sequencing project a vast number of new proteins become available with many genes remaining functionally unclassified based on evidences from sequence similarities alone. Extending similarity searches with gene pattern approaches, defined as genes sharing a distinct genomic neighbourhood, have shown to significantly improve the number of functional assignments. Further functional evidences can be gained by correlating these gene patterns with prevailing environmental parameters. MetaMine was developed to approach the large pool of unclassified proteins by searching for recurrent gene patterns across habitats based on key genes. 相似文献647.
648.
649.
650.