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   14795篇
  免费   1407篇
  国内免费   948篇
  2024年   62篇
  2023年   374篇
  2022年   384篇
  2021年   507篇
  2020年   608篇
  2019年   784篇
  2018年   746篇
  2017年   641篇
  2016年   734篇
  2015年   653篇
  2014年   722篇
  2013年   1656篇
  2012年   608篇
  2011年   643篇
  2010年   568篇
  2009年   614篇
  2008年   708篇
  2007年   691篇
  2006年   659篇
  2005年   592篇
  2004年   574篇
  2003年   528篇
  2002年   486篇
  2001年   333篇
  2000年   323篇
  1999年   253篇
  1998年   258篇
  1997年   230篇
  1996年   183篇
  1995年   152篇
  1994年   127篇
  1993年   107篇
  1992年   108篇
  1991年   61篇
  1990年   51篇
  1989年   42篇
  1988年   30篇
  1987年   34篇
  1986年   15篇
  1985年   29篇
  1984年   56篇
  1983年   36篇
  1982年   51篇
  1981年   38篇
  1980年   23篇
  1979年   14篇
  1978年   16篇
  1977年   14篇
  1975年   7篇
  1973年   6篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
771.
772.
773.
774.
775.
The evaluation of the genetic structure of autochthonous pig breeds is very important for conservation of local pig breeds and preservation of diversity. In this study, 18 microsatellite loci were used to detect genetic relationship between autochthonous pig breeds [Black Slavonian (BS), Turopolje pig (TP), and Croatian wild boar] and to determine phylogenetic relationship among Croatian autochthonous pig breeds and certain Asian and European pigs using the mitochondrial DNA (mtDNA) D-loop sequence polymorphism. Relatively high degree of genetic variation was found between the observed populations. The analysis of mtDNA showed that haplotypes of the studied pig populations are different from the other European and Chinese haplotypes. BS pigs showed some similarities with Mangalitsa and Duroc breeds. The genetic distances of TP can be explained by high degree of inbreeding during the past century. Despite the European origin of Croatian pig breeds with some impact of Chinese breeds in the past, the results of present study show that genetic diversity is still pronounced within investigated breeds. Furthermore, the genetic diversity is even more pronounced between Croatian breeds and other European and Chinese pig breeds. Thus, conservation of Croatian pig breeds will contribute to overall genetic diversity preservation of pig breeds.  相似文献   
776.
777.
Porites panamensis is a hermatypic brooder coral endemic to, and distributed along, the Eastern Tropical Pacific, and is considered a species vulnerable to local effects because it has limited capacity for long‐distance dispersal (and low genetic diversity). Although larvae of P. panamensis have been previously shown to recruit to artificial settlement platforms, they have never been observed in the water column. The present study describes the reproductive behavior of P. panamensis, with a focus on using molecular tools to document evidence for a larval planktonic stage and for successful recruitment. Larvae collected from the water column, and recruitment on natural and artificial substrata were documented. Phylogenetic analysis of two ribosomal markers, 18s rRNA and ITS (ITS1‐5.8‐ITS2), and one mitochondrial marker, cytochrome oxidase subunit 1 (cox1), confirmed the taxonomic identity of larvae, and showed that larvae and recruits have genotypes similar to adults of P. panamensis. Lipid vacuoles and Symbiodinium sp. were present in the gastrodermis of all larvae. A total of 12 and 371 recruits settled on artificial and natural substrates, respectively, and the recruitment rate differed significantly over time. By documenting the reproductive success of the species, we show the potential for existing individuals both to maintain the population in the study area and to contribute to maintenance of the coral reef community in the coming decades.  相似文献   
778.
779.
780.
斑马鱼作为一种优良的动物模型已被广泛应用于人类相关疾病机理及药物筛选的研究。由于斑马鱼骨骼发育过程和调控机制与哺乳动物高度保守,目前已成功构建斑马鱼骨骼疾病模型。本文首先介绍斑马鱼骨骼发育过程和分子调控机制,并对斑马鱼模型骨骼研究的基本方法及在骨骼药物筛选中的研究现状进行分析和总结,以期对斑马鱼作为骨骼疾病模型进行药物筛选或基础研究提供参考。  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