首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3479篇
  免费   287篇
  2023年   17篇
  2022年   34篇
  2021年   61篇
  2020年   39篇
  2019年   44篇
  2018年   66篇
  2017年   56篇
  2016年   78篇
  2015年   191篇
  2014年   191篇
  2013年   234篇
  2012年   302篇
  2011年   280篇
  2010年   163篇
  2009年   138篇
  2008年   225篇
  2007年   207篇
  2006年   204篇
  2005年   171篇
  2004年   153篇
  2003年   124篇
  2002年   130篇
  2001年   47篇
  2000年   48篇
  1999年   50篇
  1998年   51篇
  1997年   26篇
  1996年   19篇
  1995年   25篇
  1994年   31篇
  1993年   28篇
  1992年   23篇
  1991年   25篇
  1990年   21篇
  1989年   34篇
  1988年   17篇
  1987年   32篇
  1986年   14篇
  1985年   19篇
  1984年   11篇
  1983年   16篇
  1982年   13篇
  1980年   9篇
  1979年   10篇
  1978年   11篇
  1974年   9篇
  1973年   9篇
  1972年   7篇
  1971年   5篇
  1968年   5篇
排序方式: 共有3766条查询结果,搜索用时 15 毫秒
71.
The spider genus Dysdera is considered to comprise specialist isopod feeders, although the degree of specialization varies between species, depending on morphological (shape of chelicerae), behavioural (attack tactics) and metabolic (food quality of prey) adaptations. Dysdera has radiated extensively in the Canary Islands (currently 47 endemic species are described) and codistributed species have different cheliceral shapes and body sizes indicating different feeding niches. In the present study, we investigate the existence of metabolic adaptations to feeding on isopods by three endemic species (Dysdera insulana Simon, Dysdera macra Simon and Dysdera verneaui Simon) from Tenerife. We hypothesize that there is enhanced extraction efficiency of fundamental macronutrients from isopods compared with control prey in species with special morphological and behavioural adaptations for this prey type. We measure quantitatively spider growth, dry mass consumption, lipid and nitrogen consumption, and calculate growth efficiency and efficiency of utilization of dry mass, lipid and nitrogen. The results show that all three species are able to utilize both prey types, indicating that none of them are strict isopod specialist. Dysdera insulana shows enhanced growth efficiency and D. macra shows enhanced nitrogen extraction efficiency compared with D. verneaui when feeding on Porcellio rather than on Musca. Both traits indicate likely adaptations for the utilization of isopods. Spider species, sex and prey type all affect lipid and nitrogen extraction efficiencies, indicating that spiders do not simply extract nutrients in the proportions available. The results support the hypothesis that adaptations for enhanced digestion of focal prey evolve in species that already have adaptations for enhanced capture success.  相似文献   
72.
73.
74.
75.
Ecosystems - Patterns of animal migration and the ecological forces that shape them have been studied for centuries. Yet ecological impacts caused by the migration, such as altered...  相似文献   
76.
77.
Fungi play many essential roles in ecosystems. They facilitate plant access to nutrients and water, serve as decay agents that cycle carbon and nutrients through the soil, water and atmosphere, and are major regulators of macro‐organismal populations. Although technological advances are improving the detection and identification of fungi, there still exist key gaps in our ecological knowledge of this kingdom, especially related to function . Trait‐based approaches have been instrumental in strengthening our understanding of plant functional ecology and, as such, provide excellent models for deepening our understanding of fungal functional ecology in ways that complement insights gained from traditional and ‐omics‐based techniques. In this review, we synthesize current knowledge of fungal functional ecology, taxonomy and systematics and introduce a novel database of fungal functional traits (FunFun). FunFun is built to interface with other databases to explore and predict how fungal functional diversity varies by taxonomy, guild, and other evolutionary or ecological grouping variables. To highlight how a quantitative trait‐based approach can provide new insights, we describe multiple targeted examples and end by suggesting next steps in the rapidly growing field of fungal functional ecology.  相似文献   
78.
79.
The house sparrow is an important model species for studying physiological, ecological and evolutionary processes in wild populations. Here, we present a medium density, genome wide linkage map for house sparrow (Passer domesticus) that has aided the assembly of the house sparrow reference genome, and that will provide an important resource for ongoing mapping of genes controlling important traits in the ecology and evolution of this species. Using a custom house sparrow 10 K iSelect Illumina SNP chip we have assigned 6,498 SNPs to 29 autosomal linkage groups, based on a mean of 430 informative meioses per SNP. The map was constructed by combining the information from linkage with that of the physical position of SNPs within scaffold sequences in an iterative process. Averaged between the sexes; the linkage map had a total length of 2,004 cM, with a longer map for females (2,240 cM) than males (1,801 cM). Additionally, recombination rates also varied along the chromosomes. Comparison of the linkage map to the reference genomes of zebra finch, collared flycatcher and chicken, showed a chromosome fusion of the two avian chromosomes 8 and 4A in house sparrow. Lastly, information from the linkage map was utilized to conduct analysis of linkage disequilibrium (LD) in eight populations with different effective population sizes (Ne) in order to quantify the background level LD. Together, these results aid the design of future association studies, facilitate the development of new genomic tools and support the body of research that describes the evolution of the avian genome.  相似文献   
80.
Reviews in Fish Biology and Fisheries - A systematic review and meta-analysis was conducted to evaluate the appropriate tag:fish size ratio when tagging juvenile salmonids (genera Oncorhynchus,...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号