全文获取类型
收费全文 | 705篇 |
免费 | 57篇 |
出版年
2023年 | 3篇 |
2022年 | 1篇 |
2021年 | 19篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 17篇 |
2017年 | 7篇 |
2016年 | 21篇 |
2015年 | 34篇 |
2014年 | 36篇 |
2013年 | 45篇 |
2012年 | 53篇 |
2011年 | 59篇 |
2010年 | 38篇 |
2009年 | 34篇 |
2008年 | 51篇 |
2007年 | 57篇 |
2006年 | 53篇 |
2005年 | 52篇 |
2004年 | 56篇 |
2003年 | 36篇 |
2002年 | 37篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1985年 | 2篇 |
1982年 | 1篇 |
1975年 | 1篇 |
1967年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有762条查询结果,搜索用时 86 毫秒
761.
Juha Karjalainen Minna Rahkola Markku Viljanen Inna N. Andronikova Valentin A. Avinskii 《Hydrobiologia》1996,322(1-3):249-253
The results of a joint Russian-Finnish investigation on zooplankton in Lake Ladoga are presented, and a comparison is made between two sampling techniques, tube sampler and plankton net, and between two counting methods. The precision of subsampling and sampling is further discussed on the basis of zooplankton data gathered in Lake Saimaa, Finland. The comparison clearly indicates that a tube sampler is required for reliable sampling of small-sized animals, while a plankton net saves time and is a more economical sampler for large, rare or active animals. The comparison between the results obtained by Finnish and Russian workers, using different counting procedures, shows that the main groups of crustacean zooplankton are similarly counted and identified in the two laboratories. 相似文献
762.
Alexei Solovchenko Mark N. Merzlyak Inna Khozin‐Goldberg Zvi Cohen Sammy Boussiba 《Journal of phycology》2010,46(4):763-772
The responses to PAR intensity and nitrogen deficiency have been investigated in the Δ5‐desaturase‐deficient mutant (P127) of the microalga Parietochloris incisa (Reisigl) Shin Watan. (Chlorophyta, Trebouxiophyceae). The mutant accumulates dihomo‐γ‐linolenic acid (DGLA, C20:3 ω6) instead of arachidonic acid (C20:4 ω6) characteristic of the wildtype. The growth, fatty acid and pigment composition, and light absorption by P127 cell suspensions were studied for the first time during cultivation on complete and N‐free BG‐11 medium at 35, 130, and 270 μE · m?2 · s?1. On complete medium under high irradiance, an increase in biomass was observed, and total fatty acid (TFA) and DGLA contents were higher than in N‐starving cultures. A distinct irradiance‐dependent rise in carotenoid‐to‐chl ratio was recorded in P127 due to an increase in carotenoids (on complete medium) or by a decline in chl (on N‐free medium). Cultivation under high and medium irradiances caused a decline in light‐harvesting xanthophylls and an increase in β‐carotene, localized predominantly in cytoplasmic oil bodies (OB). The P127 mutant, similar to wildtype, responded to the stresses by coordinated induction of fatty acid and carotenoid syntheses, but displayed the same magnitude of the response as was observed in wildtype under 30% lower irradiance. The changes in optical properties of the P127 cultures tightly correlated with their pigment composition, and hence with fatty acid content, making it possible to develop a nondestructive technique for the assay of TFA and DGLA. The peculiarities of the stress responses in the wildtype and the mutant are discussed. 相似文献