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   396篇
  免费   21篇
  国内免费   3篇
  2023年   3篇
  2022年   2篇
  2021年   10篇
  2020年   8篇
  2019年   9篇
  2018年   5篇
  2017年   8篇
  2016年   14篇
  2015年   11篇
  2014年   15篇
  2013年   38篇
  2012年   28篇
  2011年   28篇
  2010年   11篇
  2009年   15篇
  2008年   18篇
  2007年   26篇
  2006年   9篇
  2005年   15篇
  2004年   13篇
  2003年   8篇
  2002年   7篇
  2001年   8篇
  2000年   11篇
  1999年   8篇
  1998年   4篇
  1997年   5篇
  1996年   10篇
  1994年   2篇
  1993年   2篇
  1992年   2篇
  1991年   7篇
  1990年   6篇
  1989年   2篇
  1988年   3篇
  1987年   2篇
  1986年   2篇
  1985年   5篇
  1984年   4篇
  1983年   4篇
  1979年   4篇
  1976年   2篇
  1974年   6篇
  1973年   1篇
  1970年   2篇
  1969年   4篇
  1968年   2篇
  1967年   4篇
  1966年   1篇
  1948年   1篇
排序方式: 共有420条查询结果,搜索用时 73 毫秒
411.
412.
The freshwater turtle Mauremys rivulata ranges from the Adriatic coast of the Balkan Peninsula through the Aegean region and coastal western and southern Turkey southwards to Israel. In addition, it occurs on several Aegean islands, Crete and Cyprus. Previous investigations using mtDNA sequences found virtually no genetic differentiation across its distribution range, despite some major biogeographical barriers for terrestrial and freshwater biota. Thus, the absence of any phylogeographical differentiation would be unexpected. To re‐examine genetic differentiation within M. rivulata, here we use a comprehensive rangewide sampling and information of 13 unlinked polymorphic microsatellite loci and compare these data against mtDNA variation. Our microsatellite analyses reveal a weak population structuring which conflicts, however, with most biogeographical barriers. We conclude that the genetic structure in the vast majority of the species' range has been shaped by massive transoceanic gene flow. This explanation is unlikely for the northernmost populations, which seem rather to be genetically impacted by intentionally released foreign turtles.  相似文献   
413.

Background  

Pre-processing methods for two-sample long oligonucleotide arrays, specifically the Agilent technology, have not been extensively studied. The goal of this study is to quantify some of the sources of error that affect measurement of expression using Agilent arrays and to compare Agilent's Feature Extraction software with pre-processing methods that have become the standard for normalization of cDNA arrays. These include log transformation followed by loess normalization with or without background subtraction and often a between array scale normalization procedure. The larger goal is to define best study design and pre-processing practices for Agilent arrays, and we offer some suggestions.  相似文献   
414.
G Din?ol  M Aksoy  S Erdem 《Human heredity》1979,29(5):272-278
Clinical and haematological findings of 164 Turkish beta-thalassaemic heterozygotes with increased Hb-A2 are presented. The series comprised of 19 children, 81 females and 64 males. The majority of these thalassaemic individuals were asymptomatic and only 4 of them had slight or moderate splenomegaly. The mean values of haemoglobin concentration, PCV, MCH and MCHC were significantly lower than those of the corresponding normal controls. Erythrocytosis was present in 33% of them. Hb-A2 values ranged between 3.8 and 6.1%, and between 3.8 and 6.5% as assessed by the methods of DEAE- or DE-cellulose chromatography, respectively. Hb-F was found to be above the normal range in 15.1%. It is established that beta-thalassaemia with increased Hb-A2 is the most frequent variety of thalassaemia in Turkey (80%) and both beta+- and beta0-thalassaemia genes were present in this country. The regional distribution of beta-thalassaemia in Turkey is also presented and the origin of beta-thalassaemia genes in Turkish people is discussed.  相似文献   
415.
Fourteen taxa from Chlorophyta, Rhodophyta and Phaeophyta were collected from seven stations at different depths, along the north-western Mediterranean coast of Egypt during winter and summer 2006. Total carbohydrates (TCH), total protein (TPr), total lipids (TL), chlorophyll a, β-carotene, minerals and trace metals were determined in a total of 50 specimens. The concentrations of these components varied significantly with respect to the algal taxa and showed different patterns of distribution in the three classes. The content of TCH ranged from 5 to 20.9?%, being much higher for Cystoseira spinosa (20.9?%), TPr 3.86 to 27.65?% where Gelidium corneum showed the maximum value and TL content displayed wide variation (2.34 to 48.95?%), with Sargassum hornschuchii having the highest values. A minor component was β-carotene in all samples (1.80?2.50?×?10?3 mg (100 g)?1) which was much lower than in vegetables, in contrast to chlorophyll a concentrations which have attained high values (6.70?94.20 mg (100 g)?1) and were lower than in vegetables. Mineral content was abundant in all samples and was higher than in common food and vegetables, whereas the measured trace metals all exceeded the permissible doses and were far from the accepted concentrations in the regulations of many countries. This limits their use in food consumption, except copper which recorded acceptable concentrations in the study. The maximum values of phosphorus (3,305 mg (100 g?1), potassium (930 mg (100 g?1) and calcium (3,070 mg (100 g?1) were recorded in members of Chlorophyceae: Codium bursa, Udotea sp. and Udotea petiolata, whereas the red alga Rhodymenia ardissonei had the lowest concentrations in iodine (80 ppm) and sodium (1,450 mg (100 g)?1) and the highest concentrations in the trace metals copper (3.89 ppm), nickel (13.14 ppm), zinc (38.87 ppm) and a relatively large amount of lead (41.60 ppm).  相似文献   
416.
Haptoglobin and transferrin types were examined in Eti-Turks. The Hp1 frequency was 0.26. With the exception of two individuals with transferrin D, only the transferrin C was observed. The gene frequencies were in the range of most of the Asiatic populations including Turks.  相似文献   
417.
418.
419.
420.
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