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151.
Suresh Kumar 《Plant Ecology》1996,124(1):73-93
Vegetation of 127 sites on different aspects of dune-interdunes in the Indian Thar Desert was classified using TWINSPAN. TWINSPAN groupings of sites separated better vegetated dunes of the northeast form the poorly vegetated dunes of the northwest and the southwest. Of the different ordinations using noncentred, centred and centred and standardized principal component analysis, reciprocal averaging and detrended correspondence analysis (DCA), the site and species classes in DCA correlated well with ten edaphic and ten vegetational attributes of each site. Strong correlation of vegetation groupings with soil texture, moisture holding capacity and low correlation with pH and electrical conductivity revealed the possible importance of soil physical properties in affecting vegetation composition.The 11 species classes in TWINSPAN were regrouped into 18 species classes in DCA, which separated highly frequent species from those of less and least frequent species. Based on dominance-diversity attributes, Calligonum polygonoides-Lasiurus sindicus was brought out as bioedaphic climax stage. Correlation of ordination scores in different site groupings with vegetational attributes showed specific trends: From the zero of x, y and z axes to their maximum, the ordination scores of grasses and browse species declined while score of spinous species increased. The sites near the origin of the x, y and z axes were therefore least degraded and those at or near the maximum of x, y & z axes were most disturbed as was confirmed by the dominance diversity trends. Thus trends of compositional and functional attributes of vegetation of sites in different groupings helped in inferring a site's degradation status.Abbreviations RIV
Relative importance value
- TWINSPAN
Two Way Indicator Species Analysis
- PCA
Principal Component Analysis
- RA
Reciprocal Averaging
- DCA
Detrended Correspondence Analysis
- EC
Electrical Conductivity
- WHC
Water Holding Capacity
- BD
Beta Diversity
- DC
Dominance Concentration
- WWS
Windward slope of the dune
- LWS
Leeward slope of the dune
- ID
Interdune Nomenclature: Bhandari, (1990) 相似文献
152.
Environmental risk assessment of releases of transgenic plants containing virus-derived inserts 总被引:2,自引:0,他引:2
David J. Robinson 《Transgenic research》1996,5(5):359-362
Sequences derived from the genomes of plant viruses are being used to provide virus resistance in transgenic crop plants. Although the environmental hazards associated with the release of such plants have been discussed widely, it has not been possible to reach generally acceptable conclusions about their safety. A case-by-case approach to the risk assessment of real examples is recommended as a means of building up confidence and of indicating areas of uncertainty. A logical framework for risk assessment is suggested, a key feature of which is identification of the viruses in the release environment that may infect the transgenic plants. Each of these is considered in relation to each of the three main classes of hazard (transcapsidation, recombination and synergism), and the risk associated with each event is analysed. 相似文献
153.
A. Guivarc'h J. C. Caissard A. Azmi T. Elmayan D. Chriqui M. Tepfer 《Transgenic research》1996,5(5):281-288
Among the methods now available to localize the sites of gene expression in plant materials, reporter genes based on thegus (uidA) gene ofEscherichia coli, which encodes a -glucuronidase (E.C. 3.2.1.31; GUS), have been the most widely used during the last ten years. The apparent simplicity of the histochemical GUS assay has been a major factor in the increase in articles usinggus genes. However, over the last four years, there have been occasional reports expressing doubts concerning the specificity of the observed localizations based on discrepancies between results obtained with GUS histochemistry and immunocytochemistry and/orin situ hybridization. This brief review compares the results obtained with immunocytochemistry with those obtained with various GUS substrates for histochemical studies. Certain sources of artefact are discussed, as are the limits that should be imposed on interpretation of GUS histochemistry results at the organ, tissue and cell levels. 相似文献
154.
DNA水平上的植物系统学研究方法 总被引:1,自引:0,他引:1
本文简要总结了近年来在DNA水平上的植物系统学研究方法,着重介绍了限制性长度多态性分析,PCR技术在植物系统学上的应用等这一领域最新的进展,并对分子数据的分析方法及系统树的构建进行了详细讨论。 相似文献
155.
156.
157.
湖北、河南、安徽三省大别山区地理新分布植物何家庆(安徽大学生物系合肥230039)关键词大别山区,种子植物,地理新分布THENEWGEOGRAPHICALDISTRIBUTIONOFSPERMATOPHYTEINDABIESHANTHEREGIONS... 相似文献
158.
苦楝果实活性物质研究 总被引:7,自引:0,他引:7
本文报道苦楝果实中的生物活性物质。发现果实的抽提物和单体化合物不仅具有防治作物害虫的作用,而且,还对植物有生长调节作用。通过生物活性鉴定结果表明:果实种仁的水抽提物对水稻早期萌动、发芽与秧苗的生长均有促进作用。其中,处理稻种第2天(48h),其发芽率比对照高出24.67%~42.86%;第4天秧苗的根长在1cm以上占56.5%~65.0%,而对照组只有15.5%。尤其是抽提液浓度在6000ppm时处理的稻种,测得生长10d的秧苗总长为对照的120.27%,胚根长为对照的121.54%;以及叶片中的叶绿素总含量比对照高8.5%。还证明了从果实中提取分离的几种三萜类化合物和在果实中发现的一种新化合物对苯二甲酸二甲酯,均对菜青虫有拒食和胃毒活性。 相似文献
159.
本文对特种油料植物的种质资源研究进行综述,这些植物包括含长链脂肪酸的Crambe,Limnanthes,Lunaria,短链脂肪酸的Cuphea,Lauraceae,羟基脂肪酸的Lesquerella,环氧脂肪酸的Vernonia,Stokesia,以及液体蜡酯的simmondsia等科、属的植物。 相似文献
160.
旱地玉米农田棵间蒸发研究 总被引:3,自引:0,他引:3
采用中子微区模拟装置测量旱地玉农田棵间蒸发,实验表明,本实验装置实用可行。晋西棵间蒸发量占降水量(510nm)的55%以上,棵间蒸发与蒸散的比值同时叶面积指数呈反相关,玉米产量与作物蒸腾呈正相关。 相似文献