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   509篇
  免费   37篇
  2024年   1篇
  2023年   3篇
  2022年   10篇
  2021年   18篇
  2020年   14篇
  2019年   17篇
  2018年   32篇
  2017年   18篇
  2016年   23篇
  2015年   30篇
  2014年   35篇
  2013年   43篇
  2012年   44篇
  2011年   33篇
  2010年   27篇
  2009年   24篇
  2008年   30篇
  2007年   18篇
  2006年   19篇
  2005年   15篇
  2004年   15篇
  2003年   14篇
  2002年   9篇
  2001年   10篇
  2000年   9篇
  1999年   10篇
  1998年   2篇
  1997年   4篇
  1996年   2篇
  1995年   1篇
  1992年   1篇
  1990年   2篇
  1989年   2篇
  1988年   2篇
  1987年   1篇
  1986年   1篇
  1983年   1篇
  1982年   1篇
  1980年   1篇
  1970年   1篇
  1969年   1篇
  1968年   1篇
  1967年   1篇
排序方式: 共有546条查询结果,搜索用时 843 毫秒
541.
542.
Amino Acids - Obesity in fathers leads to DNA damage and epigenetic changes in sperm that may carry potential risk factors for metabolic diseases to the next generation. Taurine (TAU)...  相似文献   
543.
We describe a fast, automated process to determine distances between mtDNA sequences allowing their subsequent clustering and haplogroup assignment that may increase the speed of data analysis and avoid human errors.In order to avoid complexities/ambiguities resulting from recurrence and insertion/deletion phenomena and thus improving evolutionary signal-to-noise ratio, protein coding sequences were compared using a vectorial representation method, and the corresponding genetic distance matrix was used for the construction of a neighbor-joining/UPGMA tree or an MDS graphic, which generally agrees with the consensus mtDNA phylogeny.mtDNAoffice software, detailed instructions and example files are freely available on the web at http://www.portugene.com/SupMat/setupmtDNAoffice.rar.  相似文献   
544.
The present work investigated the effect of the interval of serial sections of ovarian tissue on the number of isolated preantral follicles in the goat. Goat ovaries were cut in the tissue chopper at eight different intervals. The quality of isolated follicles were evaluated by histology and transmission electron microscopy. Best results were obtained when the ovaries were cut in the tissue chopper at intervals of 75.0 microm (9664 preantral follicles per ovary). Histochemical and ultrastructural analysis showed that the follicular morphology was preserved after mechanical isolation as demonstrated by the normality of oocytes and granulosa cells as well as by preservation of basement membrane. The percentages of isolated primordial, primary and secondary follicles were 96.3%, 2.5%, and 1.2% and their average diameters were 21.5, 34.7 and 65.3 microm, respectively. It was concluded that the interval of serial sections of ovarian tissue in the tissue chopper affects the number of isolated preantral follicles, and that the follicles remained intact after mechanical isolation in goats.  相似文献   
545.
546.
Abstract

Sinusichnus Gibert 1996 Gibert, J. M. d. 1996. “A New Decapod Burrow System from the NW Mediterranean Pliocene.” Revista Española de Paleontología 11: 251254. [Google Scholar] is recorded for the first time in the Oligocene-Miocene Pirabas Formation of Northern Brazil. In these Oligocene-Miocene carbonate deposits, Sinusichnus sinuosus is characterized by horizontal, highly regular sinusoidal burrow systems with T- and H-shaped branching points. The main difference between the S. sinuosus described herein and other occurrences worldwide is the anomalous diameter of the burrows (4 to 10?cm). These trace fossils occur in organic matter-rich, wackestone/packstone and laminated mudstones interbedded with boundstones deposited in an inner carbonate platform paleoenvironment. The exceptional size of the studied S. sinuosus could have been associated to the producer’s size, which may be attributed to construction by large crustaceans, similar to fossils found within the Pirabas Formation. Also, the sinusoidal morphology and retrusive spreiten could be a result of the fodinichnial/domichnial behavior.  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