全文获取类型
收费全文 | 128870篇 |
免费 | 9449篇 |
国内免费 | 45篇 |
出版年
2023年 | 701篇 |
2022年 | 1140篇 |
2021年 | 2299篇 |
2020年 | 1786篇 |
2019年 | 2041篇 |
2018年 | 3310篇 |
2017年 | 2974篇 |
2016年 | 4233篇 |
2015年 | 5760篇 |
2014年 | 5925篇 |
2013年 | 7747篇 |
2012年 | 9048篇 |
2011年 | 8378篇 |
2010年 | 5349篇 |
2009年 | 4668篇 |
2008年 | 6375篇 |
2007年 | 6090篇 |
2006年 | 5756篇 |
2005年 | 5515篇 |
2004年 | 5373篇 |
2003年 | 4746篇 |
2002年 | 4098篇 |
2001年 | 3036篇 |
2000年 | 2925篇 |
1999年 | 2470篇 |
1998年 | 1239篇 |
1997年 | 1063篇 |
1996年 | 1092篇 |
1995年 | 926篇 |
1994年 | 837篇 |
1993年 | 793篇 |
1992年 | 1573篇 |
1991年 | 1367篇 |
1990年 | 1263篇 |
1989年 | 1253篇 |
1988年 | 1205篇 |
1987年 | 1120篇 |
1986年 | 1031篇 |
1985年 | 1026篇 |
1984年 | 966篇 |
1983年 | 720篇 |
1982年 | 619篇 |
1981年 | 553篇 |
1980年 | 530篇 |
1979年 | 695篇 |
1978年 | 608篇 |
1977年 | 474篇 |
1975年 | 522篇 |
1974年 | 545篇 |
1973年 | 554篇 |
排序方式: 共有10000条查询结果,搜索用时 630 毫秒
141.
S. H. Habib S.-E. Ooi Ond?ej Novák Danu?e Tarkowská Jakub Rol?ík Karel Dole?al S. S. R. Syed-Alwee C.-L. Ho P. Namasivayam 《Plant Growth Regulation》2012,68(2):313-317
Comparative mineral and hormonal analyses were made on tissue culture derived truncated leaf syndrome and wild type oil palm seedlings. Mineral analysis confirmed that Boron, Zinc and chlorophyll levels were significantly lower in truncated leaf syndrome leaves than those of wild type. Hormonal analysis also revealed various cytokinin derivatives such as trans-zeatin, trans-zeatin riboside, trans-zeatin O-glucoside and trans-zeatin riboside 5??mono phosphate were significantly higher in truncated leaf syndrome leaves compared to wild type leaves. Brassinolide level was also significantly higher in truncated leaf syndrome leaves than those of the wild type. These observations suggest that the truncated leaf syndrome abnormality could be associated to high cytokinin and brassinosteroid production which affects the uptake of Boron and Zinc. 相似文献
142.
143.
144.
Jeroen M. G. Stevens Hilde Vervaecke Han de Vries Linda van Elsacker 《International journal of primatology》2007,28(6):1417-1430
Bonobos have a reputation as a female-dominated and egalitarian species. We examined the 2 aspects of dominance in 6 captive
bonobo groups. Females do not consistently evoke submission from all males in all contexts. Though females occupy the highest-ranking
positions in the dominance hierarchy, there are in each group males that obtain rather high ranks and are able to dominate
≥1 female. Thus female dominance is not complete and hierarchies can be better described as nonexclusive female dominance.
We studied egalitarianism by measuring linearity and steepness of dominance hierarchies. The hierarchies of all groups are
highly linear. Hierarchies among males are steeper than among females. On average, male bonobos are more despotic than females,
but females too can have despotic relations, both with other females and with males. Hence one can call bonobos in captivity
semidespotic rather than egalitarian. 相似文献
145.
David Gutirrez‐Larruscain Santiago Andrs‐Snchez Enrique Rico María Montserrat Martínez‐Ortega 《植物分类学报:英文版》2019,57(1):42-54
Forty-five populations of Pentanema corresponding to seven species included in the Pentanema conyzae clade have been studied using AFLP fingerprinting. The results show that allopolyploidization could have been involved in the diversification of this group, specifically in species P. langeanum and P. maletii. Molecular data confirm the presence of P. britannicum in the Iberian Peninsula and key steps are provided to identify the species that are morphologically the most challenging. 相似文献
146.
Martin T. R. Kuiper Marijke Holtrop Hans de Vries 《Molecular & general genetics : MGG》1988,213(2-3):519-528
147.
Hydrobiologia - In shallow lakes, macrophytes have important effects on food webs, community structure and nutrient dynamics. For this reason they play a significant role in the restoration of... 相似文献
148.
149.