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   1277779篇
  免费   114006篇
  国内免费   1449篇
  1393234篇
  2021年   17705篇
  2020年   12542篇
  2019年   16097篇
  2018年   16994篇
  2017年   15768篇
  2016年   27535篇
  2015年   42018篇
  2014年   50065篇
  2013年   76296篇
  2012年   34034篇
  2011年   21589篇
  2010年   42280篇
  2009年   44009篇
  2008年   21140篇
  2007年   18726篇
  2006年   24787篇
  2005年   25930篇
  2004年   25236篇
  2003年   23052篇
  2002年   21096篇
  2001年   28385篇
  2000年   25570篇
  1999年   27174篇
  1998年   24846篇
  1997年   24691篇
  1996年   24441篇
  1995年   22483篇
  1994年   22360篇
  1993年   21438篇
  1992年   24361篇
  1991年   22798篇
  1990年   21417篇
  1989年   22462篇
  1988年   20656篇
  1987年   19865篇
  1986年   18854篇
  1985年   20844篇
  1984年   21165篇
  1983年   18874篇
  1982年   19930篇
  1981年   19314篇
  1980年   17982篇
  1979年   17698篇
  1978年   16919篇
  1977年   16290篇
  1976年   15679篇
  1975年   14968篇
  1974年   15512篇
  1973年   15788篇
  1972年   13445篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Glushakova  A. M.  Lysak  L. V.  Kachalkin  A. V.  Ivanova  A. E.  Umarova  A. B.  Abramyan  I. A.  Ezhelev  Z. S.  Maksimova  I. A. 《Microbiology》2021,90(2):176-186
Microbiology - In a model experiment, the transformation of microbial complexes of cultivated saprotrophic bacteria and yeasts during freezing-thawing was studied in various natural substrates that...  相似文献   
992.
Microbiology - The surface of the MA8 magnesium alloy, modified by laser treatment, was found to acquire superhydrophilic properties and high bactericidal activity against Escherichia coli K12...  相似文献   
993.
Ding  Jingyi  Eldridge  David J. 《Plant and Soil》2021,459(1-2):173-183
Plant and Soil - Perennial plants play important roles in maintaining ecosystem functions by forming fertile islands beneath their canopies. Little is known about how the fertile island effect...  相似文献   
994.
Islam  M.D. Dhin  Price  Adam H.  Hallett  Paul D. 《Plant and Soil》2021,467(1-2):515-530
Plant and Soil - Cracks and biopores in compacted soil such as plough pans could aid deep rooting, mitigating constraints to seasonal upland use of paddy fields for rice production. This research...  相似文献   
995.
Journal of Evolutionary Biochemistry and Physiology - A study of the effect of a seasonal decrease in ambient temperature on the composition of free amino acids and ninhydrin-positive secondary...  相似文献   
996.
Journal of Evolutionary Biochemistry and Physiology - Glutamatergic transmission is responsible for most of excitatory synaptic processes in the central nervous system of vertebrates. Glutamatergic...  相似文献   
997.
Journal of Evolutionary Biochemistry and Physiology - Due to a high occurrence of diabetes mellitus (DM) and its complications, insulin-positive cells detected in different organs are of great...  相似文献   
998.
Journal of Evolutionary Biochemistry and Physiology - Changes in bioelectrical impedance of the myocardium and liver were revealed in male Wistar rats chronically exposed to doxorubicin....  相似文献   
999.
1000.
Vertebrate metamorphosis is often marked by dramatic morphological and physiological changes of the alimentary tract, along with major shifts in diet following development from larva to adult. Little is known about how these developmental changes impact the gut microbiome of the host organism. The metamorphosis of the sea lamprey (Petromyzon marinus) from a sedentary filter-feeding larva to a free-swimming sanguivorous parasite is characterized by major physiological and morphological changes to all organ systems. The transformation of the alimentary canal includes closure of the larval esophagus and the physical isolation of the pharynx from the remainder of the gut, which results in a nonfeeding period that can last up to 8 months. To determine how the gut microbiome is affected by metamorphosis, the microbial communities of feeding and nonfeeding larval and parasitic sea lamprey were surveyed using both culture-dependent and -independent methods. Our results show that the gut of the filter-feeding larva contains a greater diversity of bacteria than that of the blood-feeding parasite, with the parasite gut being dominated by Aeromonas and, to a lesser extent, Citrobacter and Shewanella. Phylogenetic analysis of the culturable Aeromonas from both the larval and parasitic gut revealed that at least five distinct species were represented. Phenotypic characterization of these isolates revealed that over half were capable of sheep red blood cell hemolysis, but all were capable of trout red blood cell hemolysis. This suggests that the enrichment of Aeromonas that accompanies metamorphosis is likely related to the sanguivorous lifestyle of the parasitic sea lamprey.  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