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   727篇
  免费   52篇
  国内免费   7篇
  2023年   5篇
  2022年   17篇
  2021年   13篇
  2020年   14篇
  2019年   17篇
  2018年   25篇
  2017年   29篇
  2016年   26篇
  2015年   22篇
  2014年   43篇
  2013年   82篇
  2012年   24篇
  2011年   40篇
  2010年   38篇
  2009年   45篇
  2008年   27篇
  2007年   41篇
  2006年   17篇
  2005年   23篇
  2004年   15篇
  2003年   19篇
  2002年   13篇
  2001年   25篇
  2000年   21篇
  1999年   9篇
  1998年   9篇
  1997年   9篇
  1996年   6篇
  1995年   6篇
  1994年   7篇
  1993年   7篇
  1992年   7篇
  1991年   3篇
  1990年   7篇
  1989年   7篇
  1988年   3篇
  1987年   6篇
  1986年   6篇
  1985年   2篇
  1984年   9篇
  1983年   5篇
  1982年   7篇
  1981年   8篇
  1980年   6篇
  1979年   2篇
  1978年   2篇
  1976年   2篇
  1975年   3篇
  1974年   3篇
  1970年   1篇
排序方式: 共有786条查询结果,搜索用时 31 毫秒
51.
A new genus, Altihoratosphaga, is erected for species formerly assigned to Horatosphaga Schaum, 1853, and a new species is described. Four species are included in Altihoratosphaga: Altihoratosphaga nomima (Karsch, 1896), Altihoratosphaga montivaga ( Sjöstedt, 1909 ), Altihoratosphaga nou (Hemp, 2007) and Altihoratosphaga hanangensis sp. nov. All four species are restricted to Tanzanian localities, and, except for A. nomima, for which no ecological data are available, are confined to montane forest habitats. Data on ecology, acoustics, chromosomes, and molecular relationships are provided, as well as a key to Altihoratosphaga species. The present‐day distribution of Altihoratosphaga species suggests former migration events at times when wetter and colder climatic fluctuations favoured connections between montane forest communities, which today are isolated, enabling flightless taxa such as Altihoratosphaga and Monticolaria to spread. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 66–82.  相似文献   
52.
Four anthocyanins, cyanidin 3-O-(2″-(5?-(E-p-coumaroyl)-β-apiofuranosyl)-β-xylopyranoside)-5-O-β-glucopyranoside, cyanidin 3-O-(2″-(5?-(E-p-coumaroyl)-β-apiofuranosyl)-β-xylopyranoside), cyanidin 3-O-(2″-(5?-(E-caffeoyl)-β-apiofuranosyl)-β-xylopyranoside) and cyanidin 3-O-(2″-(5?-(E-feroyl)-β-apiofuranosyl)-β-xylopyranoside) were isolated from leaves of African milk bush, (Synadeniumgrantii Hook, Euphorbiaceae) together with the known cyanidin 3-O-β-xylopyranoside-5-O-β-glucopyranoside and cyanidin 3-O-β-xyloside. The four former pigments are the first reported anthocyanins containing the monosaccharide apiose, and the three 5?-cinnamoyl derivative-2″-(β-apiosyl)-β-xyloside subunits have previously not been reported for any compound.  相似文献   
53.
54.
The commercially available dog food samples (29 dry foods and 11 wet foods) were analysed for deoxynivalenol (DON) and ochratoxin A (OTA) using ELISA. All (100%) dry foods were contaminated with DON with various amount of the toxin (22-1837 μg/kg). In wet food 3 samples were found to be positive for DON in the range of 95-170 μg/kg. There were a few samples contaminated with OTA: 3 samples in dry foods (7-40 μg/kg) and 2 samples in wet foods (45 and 115 μg/kg).  相似文献   
55.
56.
57.
Despite advances in chemotherapy, radiotherapy and targeted drug development, cancer remains a disease of high morbidity and mortality. The treatment of human cancer patients with chemotherapy has become commonplace and accepted over the past 100 years. In recent years, and with a similar incidence of cancer to people, the use of cancer chemotherapy drugs in veterinary patients such as the dog has also become accepted clinical practice. The poor predictability of tumour responses to cancer chemotherapy drugs in rodent models means that the standard drug development pathway is costly, both in terms of money and time, leading to many drugs failing in Phase I and II clinical trials. This has led to the suggestion that naturally occurring cancers in pet dogs may offer an alternative model system to inform rational drug development in human oncology. In this review, we will explore the species variation in tumour responses to conventional chemotherapy and highlight our understanding of the differences in pharmacodynamics, pharmacokinetics and pharmacogenomics between humans and dogs. Finally, we explore the potential hurdles that need to be overcome to gain the greatest value from comparative oncology studies.  相似文献   
58.
59.
Haptoglobin (Hp), serum amyloid A (SAA), C-reactive protein (CRP), white blood cells (WBC), reactive oxygen metabolites (ROMs), the antioxidant barrier (Oxy-adsorbent) and thiol groups of plasma compounds (SHp) were measured in ten dogs that had been transported a distance of about 230 km within 2 h (experimental group) and in ten dogs that had not been subjected to road transportation (control group). Blood was collected via cephalic venipuncture before road transportation (T0), after road transportation (T1), and more than 6 (T6) and 24 (T24) hours after road transportation in the experimental group (Group A) and at the same time points in the control group (Group B). The GLM (general linear model) Repeated Measures procedure showed a significant difference between the two groups (P<0.0001) and a significant rise (P<0.0001) in the concentrations of Hp, SAA, CRP, WBC, ROMs, Oxy-adsorbent and SHp after road transportation in Group A, underlining that physiological and homeostatic mechanisms are modified differently at various sampling times.  相似文献   
60.
Hybridization between wild species and their domestic counterparts may represent a major threat to natural populations. However, high genetic similarity between the hybridizing taxa makes the detection of hybrids a difficult task and may hinder attempts to assess the impact of hybridization in conservation biology. In this work, we used a combination of 42 autosomal microsatellites together with Y-chromosome microsatellite-defined haplotypes and mtDNA sequences to investigate the occurrence and dynamics of wolf-dog hybridization in the Iberian Peninsula. To do this, we applied a variety of Bayesian analyses and a parallel set of simulation studies to evaluate (i) the differences between Iberian wolves and dogs, (ii) the frequency and geographical distribution of hybridization and (iii) the directionality of hybridization. First, we show that Iberian wolves and dogs form two well-differentiated genetic entities, suggesting that introgressive hybridization is not a widespread phenomenon shaping both gene pools. Second, we found evidence for the existence of hybridization that is apparently restricted to more peripheral and recently expanded wolf populations. Third, we describe compelling evidence suggesting that the dynamics of hybridization in wolf populations is mediated by crosses between male dogs and female wolves. More importantly, the observation of a population showing the occurrence of a continuum of hybrid classes forming mixed packs may indicate that we have underestimated hybridization. If future studies confirm this pattern, then an intriguing avenue of research is to investigate how introgression from free-ranging domestic dogs is enabling wolf populations to adapt to the highly humanized habitats of southern Europe while still maintaining their genetic differentiation.  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