全文获取类型
收费全文 | 796篇 |
免费 | 59篇 |
出版年
2023年 | 7篇 |
2022年 | 7篇 |
2021年 | 26篇 |
2020年 | 19篇 |
2019年 | 15篇 |
2018年 | 26篇 |
2017年 | 33篇 |
2016年 | 43篇 |
2015年 | 30篇 |
2014年 | 48篇 |
2013年 | 52篇 |
2012年 | 46篇 |
2011年 | 45篇 |
2010年 | 33篇 |
2009年 | 29篇 |
2008年 | 25篇 |
2007年 | 34篇 |
2006年 | 20篇 |
2005年 | 21篇 |
2004年 | 31篇 |
2003年 | 29篇 |
2002年 | 23篇 |
2001年 | 16篇 |
2000年 | 14篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1992年 | 7篇 |
1991年 | 11篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1986年 | 11篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 10篇 |
1978年 | 4篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 7篇 |
1973年 | 4篇 |
1969年 | 4篇 |
1968年 | 6篇 |
1966年 | 5篇 |
排序方式: 共有855条查询结果,搜索用时 15 毫秒
821.
822.
823.
Godar Sene Mansour Thiao Ramatoulaye Samba-Mbaye Damase Khasa Aboubacry Kane Mame Samba Mbaye Marie-Ève Beaulieu Anicet Manga Samba Ndao Sylla 《Microbial ecology》2013,65(1):128-144
Several fast-growing and multipurpose tree species have been widely used in West Africa to both reverse the tendency of land degradation and restore soil productivity. Although beneficial effects have been reported on soil stabilization, there still remains a lack of information about their impact on soil microorganisms. Our investigation has been carried out in exotic and native tree plantations of 28 years and aimed to survey and compare the abundance and genetic diversity of natural legume-nodulating rhizobia (LNR). The study of LNR is supported by the phylogenetic analysis which clustered the isolates into three genera: Bradyrhizobium, Mesorhizobium, and Sinorhizobium. The results showed close positive correlations between the sizes of LNR populations estimated both in the dry and rainy seasons and the presence of legume tree hosts. There were significant increases in Rhizobium spp. population densities in response to planting with Acacia spp., and high genetic diversities and richness of genotypes were fittest in these tree plantations. This suggests that enrichment of soil Rhizobium spp. populations is host specific. The results indicated also that species of genera Mesorhizobium and Sinorhizobium were lacking in plantations of non-host species. By contrast, there was a widespread distribution of Bradyrhizobium spp. strains across the tree plantations, with no evident specialization in regard to plantation type. Finally, the study provides information about the LNR communities associated with a range of old tree plantations and some aspects of their relationships to soil factors, which may facilitate the management of man-made forest systems that target ecosystem rehabilitation and preservation of soil biota. 相似文献
824.
825.
Keramati Hassan Miri Ali Baghaei Mehdi Rahimizadeh Aziz Ghorbani Raheb Fakhri Yadolah Bay Abotaleb Moradi Masoud Bahmani Zohreh Ghaderpoori Mansour Mousavi Khaneghah Amin 《Biological trace element research》2019,188(2):261-273
Biological Trace Element Research - A systematic review, meta-analysis, and non-carcinogenic risk considering fluoride content of drinking water resources of 31 provinces of Iran among some... 相似文献
826.
827.
828.
M. Magdy F. Mansour OK Young Lee-Stadelmann Eduard J. Stadelmann 《Physiologia plantarum》1993,88(1):141-148
Salinity effects on the cell membranes of four lines of wheat ( Triticum aestivum L.). and two cultivars of barley ( Hordeum vulgare L.), differing in salt resistance were investigated. Plants were grown for 10 days in 1/4-strength Hoagland solution and then for 5 more days in 1/4-strength Hoagland with and without NaCl (100 m M ) or (for Hordeum only) polyethylene glycol (PEG). Permeability to three non-electrolytes (urea, methylurea and ethylurea) of subepidermal cells of leaf sheaths ( Triticum ) and coleoptiles ( Hordeum ) was determined and membrane partiality calculated, a parameter which numerically indicates the degree of lipophilicity of a membrane. Non-electrolyte permeability significantly increased and membrane partiality decreased in the salt sensitive cultivars or lines under salt stress. Neither parameter changed significantly in the salt resistant lines and cultivar in a saline environment. Osmotic stress in Hordeum by PEG 10000 had no significant effect on permeability and thus membrane partiality neither in sensitive nor in resistant cultivars.
The osmotic component of salinity stress did not seem to be a major factor causing injury, rather ion toxicity may be a cause of cell damage. The results indicate differences in the membrane between salt sensitive and salt resistant genotypes. Salt resistance seems to be controlled by genetic factors independent of external salinity levels. 相似文献
The osmotic component of salinity stress did not seem to be a major factor causing injury, rather ion toxicity may be a cause of cell damage. The results indicate differences in the membrane between salt sensitive and salt resistant genotypes. Salt resistance seems to be controlled by genetic factors independent of external salinity levels. 相似文献
829.
830.