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   50474篇
  免费   4072篇
  国内免费   5210篇
  2024年   130篇
  2023年   630篇
  2022年   1421篇
  2021年   2381篇
  2020年   1657篇
  2019年   2102篇
  2018年   2172篇
  2017年   1829篇
  2016年   2295篇
  2015年   2656篇
  2014年   3454篇
  2013年   3660篇
  2012年   4246篇
  2011年   4015篇
  2010年   2850篇
  2009年   2531篇
  2008年   2916篇
  2007年   2612篇
  2006年   2309篇
  2005年   1926篇
  2004年   1759篇
  2003年   1619篇
  2002年   1360篇
  2001年   1106篇
  2000年   945篇
  1999年   660篇
  1998年   413篇
  1997年   343篇
  1996年   328篇
  1995年   326篇
  1994年   301篇
  1993年   234篇
  1992年   297篇
  1991年   265篇
  1990年   215篇
  1989年   199篇
  1988年   135篇
  1987年   181篇
  1986年   148篇
  1985年   131篇
  1984年   104篇
  1983年   99篇
  1982年   86篇
  1981年   79篇
  1980年   53篇
  1979年   62篇
  1978年   66篇
  1976年   51篇
  1973年   63篇
  1972年   52篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Kim  Juseok  Kim  Joon Yong  Song  Hye Seon  Kim  Yeon Bee  Whon  Tae Woong  Ahn  Seung Woo  Lee  Se Hee  Yoo  SeungRan  Kim  Yu Jin  Myoung  Jinjong  Choi  Yoon-E  Son  Hong-Seok  Roh  Seong Woon 《Antonie van Leeuwenhoek》2021,114(5):507-513

Strain CBA3638T was isolated from the Geum River sediment, Republic of Korea. The cells of strain CBA3638T were Gram-stain-positive, strictly anaerobic, rod-shaped, and 0.5–1.0 μm wide, and 4.0–4.5 μm long. Optimal growth occurred at 37 °C, pH 7.0, and 1.0% (w/v) NaCl. Based on the 16S rRNA gene sequence, the phylogenetic analysis showed that strain CBA3638T belongs to the genus Anaerocolumna in the family Lachnospiraceae, and is most closely related to Anaerocolumna cellulosilytica (94.6–95.0%). The DDH value with A. cellulosilytica SN021T showed 15.0% relatedness. The genome of strain CBA3638T consisted of one circular chromosome that is 5,500,435 bp long with a 36.7 mol% G?+?C content. The genome contained seven 16S-5S-23S rRNA operons and one antibiotic resistance-related transporter gene (mefA). Quinones were not detected. The predominant cellular fatty acids were C16:0 and C14:0 and the polar lipids were diphosphatidylglycerol, phosphatidylcholine, and uncharacterised polar lipids. Based on the polyphasic taxonomic analysis, we propose strain CBA3638T as a novel species in the genus Anaerocolumna, with the name Anaerocolumna sedimenticola sp. nov. The type strain is CBA3638T (=?KACC 21652T?=?DSM 110663T).

  相似文献   
942.
Yu  Xianglong  Liu  Jianxin  Li  Huizi  Liu  Boyang  Zhao  Bingqian  Ning  Zhangyong 《Biochemical genetics》2021,59(3):799-812

Atypical porcine pestivirus (APPV) is an emerging novel pestivirus causing the congenital tremor (CT) in piglets. The worldwide distribution characteristic of APPV make it a threat to global swine health. E2 is the major envelope glycoprotein of APPV and the crucial target for vaccine development. Considering the genetic variability of APPV complete genomes and its E2 gene as well as gaps for codon analysis, a comprehensive analysis of codon usage patterns was performed. Relative synonymous codon usage (RSCU) and effective number of codon (ENC) analyses showed that a relatively instable change existed and a slight low codon usage bias (CUB) were displayed in APPV genomes. ENC-plot analysis and correlation analyses of nucleotide compositions and ENC showed that mutation pressure and natural selection both affected the codon usage bias of the APPV and natural selection had a more obvious influence for E2 gene compared with complete genomes. Principal component analysis (PCA) and correlation analyses confirmed the above results. Correlation analyses between Gravy and Aromaticity values and the codon bias showed that natural selection played an important role in shaping the synonymous codon bias. Furthermore, neutrality plot analysis showed that natural selection was the main force while mutation pressure was a minor force influencing the codon usage pattern of the APPV E2 gene and complete genomes. The results could illustrate the codon usage patterns of APPV genomes and provided valuable basic data for further fundamental research of evolution of APPV.

  相似文献   
943.
944.
Entomological Review - The state of the natural foci of tick-borne encephalitis (TBE) was monitored during 15 seasons (2005–2019) in several key plots within a popular recreational and...  相似文献   
945.
Kotti  B. K.  Klimova  L. I.  Ermolova  N. V.  Artyushina  Yu. S.  Bammatov  D. M. 《Entomological Review》2021,101(9):1266-1272
Entomological Review - The Eastern Caucasian highland natural plague focus is located on the northern slope of the Main Caucasian Range. This peculiar region has a rich fauna of rodent fleas...  相似文献   
946.
947.
The use of chaotropic reagents is common in biophysical characterization of biomolecules. When the study involves transmembrane protein channels, the stability of the protein channel and supporting bilayer membrane must be considered. In this letter, we show that planar bilayers composed of poly(1,2-butadiene)-b-poly(ethylene oxide) diblock copolymer are stable and leak-free at high guanidinium chloride concentrations, in contrast to diphytanoyl phosphatidylcholine bilayers, which exhibit deleterious leakage under similar conditions. Furthermore, insertion and functional analysis of channels such as α-hemolysin and MspA are straightforward in these polymer membranes. Finally, we demonstrate that α-hemolysin channels maintain their structural integrity at 2 M guanidinium chloride concentrations using blunt DNA hairpins as molecular reporters.  相似文献   
948.
949.
950.
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