全文获取类型
收费全文 | 1426篇 |
免费 | 143篇 |
国内免费 | 123篇 |
出版年
2024年 | 2篇 |
2023年 | 35篇 |
2022年 | 23篇 |
2021年 | 40篇 |
2020年 | 61篇 |
2019年 | 53篇 |
2018年 | 46篇 |
2017年 | 72篇 |
2016年 | 56篇 |
2015年 | 53篇 |
2014年 | 65篇 |
2013年 | 92篇 |
2012年 | 46篇 |
2011年 | 47篇 |
2010年 | 54篇 |
2009年 | 48篇 |
2008年 | 65篇 |
2007年 | 70篇 |
2006年 | 75篇 |
2005年 | 65篇 |
2004年 | 41篇 |
2003年 | 35篇 |
2002年 | 49篇 |
2001年 | 51篇 |
2000年 | 40篇 |
1999年 | 22篇 |
1998年 | 33篇 |
1997年 | 23篇 |
1996年 | 52篇 |
1995年 | 18篇 |
1994年 | 24篇 |
1993年 | 14篇 |
1992年 | 14篇 |
1991年 | 18篇 |
1990年 | 11篇 |
1989年 | 18篇 |
1988年 | 7篇 |
1987年 | 21篇 |
1986年 | 12篇 |
1985年 | 18篇 |
1984年 | 41篇 |
1983年 | 4篇 |
1982年 | 9篇 |
1981年 | 15篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1973年 | 1篇 |
排序方式: 共有1692条查询结果,搜索用时 15 毫秒
1.
2.
Janne Alahuhta Sarian Kosten Munemitsu Akasaka Dominique Auderset Mattia M. Azzella Rossano Bolpagni Claudia P. Bove Patricia A. Chambers Eglantine Chappuis John Clayton Mary de Winton Frauke Ecke Esperança Gacia Gana Gecheva Patrick Grillas Jennifer Hauxwell Seppo Hellsten Jan Hjort Mark V. Hoyer Christiane Ilg Agnieszka Kolada Minna Kuoppala Torben Lauridsen En Hua Li Balázs A. Lukács Marit Mjelde Alison Mikulyuk Roger P. Mormul Jun Nishihiro Beat Oertli Laila Rhazi Mouhssine Rhazi Laura Sass Christine Schranz Martin Søndergaard Takashi Yamanouchi Qing Yu Haijun Wang Nigel Willby Xiao Ke Zhang Jani Heino 《Journal of Biogeography》2017,44(8):1758-1769
3.
Various laboratory techniques have been utilized worldwide for measuring lead-210 in sub-recent deposits through its grand-daughter product polonium-210. Isotope dilution alpha spectrometry proved a suitable tool for absolute determination of lead-210 for the dating of aquatic deposits. Moreover, isotope dilution alpha spectrometry along with speciation experiments can be used to resolve depositional anomalies arising from supported lead-210/Ra-226 disequilibrium levels and unsupported lead-210 mobile fractions. Isotope dilution alpha spectrometry of sub-recent sediment and peat deposits has been critically evaluated for more than ten years. Our results show that type, size and composition of deposits analyzed as well as radiochemical procedures used, together with alpha counting techniques, are important factors influencing lead-210 determinations and tailing corrections using its granddaughter product polonium-210. Optimization of these parameters is of prime importance to achieve economic and accurate analyses, especially at low lead-210 concentrations and small sample sizes. 相似文献
4.
5.
The lipid composition of swimming spores, cysts and five hour germlings was established. Spores utilized triglycerides first, then phospholipids. Upon encystment all glycolipid components decreased, while in germlings the phospholipids, monoglycerides and sterol esters exhibited a marked increase. 相似文献
6.
7.
8.
DIFFERENTIAL EXPRESSION OF DIEL ACID METABOLISM IN TWO LIFE FORMS OF LITTORELLA UNIFLORA (L.) ASCHERS 总被引:1,自引:0,他引:1
K. AULIO 《The New phytologist》1985,100(4):533-536
9.
《Journal of Plant Interactions》2013,8(2):91-99
Abstract The present research work focused on the metal translocation in the soil-plant system and subsequent metal stress on biochemical response of aquatic macrophytes growing along an industrial waste discharge channel. The bottom sediment of the effluent channel is highly contaminated with metals. High transfer factor (TF) for most of the metals indicated higher metal uptake by aquatic macrophytes of which Typha sp. was found to be the most suitable. Average TF was in the order of Fe (4.82) > Mn (3.91) > Cu (3.59) > Cd (2.29) > Zn (2.22) > Cr (1.83) > Pb (1.80). Hyper accumulation of metals within plants resulted in significant reductions in total chlorophyll, soluble sugar with an increase in protein and proline content. The investigation also demonstrated that exposure to high concentrations on metals resulted in enhanced activity of catalase (61.82–90.91%) and peroxidase (37.08–70.23%) in all examined macrophytes with a reduced (27.58–43.4%) or unchanged ascorbate peroxidase activity depending on plant species. 相似文献
10.
Ervin Pihu 《Hydrobiologia》1996,340(1-3):163-172
The management of aquatic weeds in an irrigation scheme is constrained by the agro-economic system in relation to scheme layout, the nature and ecology of the aquatic weeds, agricultural practice, irrigation and drainage requirements, and the available resources for maintenance. The way in which the ecology, engineering and economics of irrigation and drainage channels interact to produce a pattern of management is investigated for the Mwea Irrigation Settlement Scheme, Central Province, Kenya. This is used to develop a simple model which enables the economic implications of varying the aquatic weed management practice to be identified. The model brings the selection of a weed control programme within the principles of engineering economy. 相似文献