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   1290篇
  免费   77篇
  1367篇
  2023年   7篇
  2022年   19篇
  2021年   28篇
  2020年   15篇
  2019年   23篇
  2018年   35篇
  2017年   27篇
  2016年   51篇
  2015年   45篇
  2014年   59篇
  2013年   69篇
  2012年   110篇
  2011年   108篇
  2010年   70篇
  2009年   56篇
  2008年   89篇
  2007年   68篇
  2006年   92篇
  2005年   67篇
  2004年   47篇
  2003年   47篇
  2002年   38篇
  2001年   13篇
  2000年   7篇
  1999年   11篇
  1998年   11篇
  1997年   10篇
  1996年   10篇
  1994年   11篇
  1993年   8篇
  1992年   9篇
  1991年   11篇
  1990年   5篇
  1989年   11篇
  1988年   4篇
  1987年   6篇
  1986年   4篇
  1984年   4篇
  1982年   3篇
  1979年   4篇
  1978年   5篇
  1977年   3篇
  1976年   3篇
  1975年   3篇
  1974年   7篇
  1967年   4篇
  1965年   4篇
  1963年   4篇
  1958年   5篇
  1957年   3篇
排序方式: 共有1367条查询结果,搜索用时 0 毫秒
41.
42.
43.
The temporal and spatial organization of the annual cycle according to local conditions is of crucial importance for individuals’ fitness. Moreover, which sites and when particular sites are used can have profound consequences especially for migratory animals, because the two factors shape interactions within and between populations, as well as between animal and the environment. Here, we compare spatial and temporal patterns of two latitudinally separated breeding populations of a trans‐Equatorial passerine migrant, the collared flycatcher Ficedula albicollis, throughout the annual cycle. We found that migration routes and non‐breeding residency areas of the two populations largely overlapped. Due to climatic constraints, however, the onset of breeding in the northern population was approximately two weeks later than that of the southern population. We demonstrate that this temporal offset between the populations carries‐over from breeding to the entire annual cycle. The northern population was consistently later in timing of all subsequent annual events – autumn migration, non‐breeding residence period, spring migration and the following breeding. Such year‐round spatiotemporal patterns suggest that annual schedules are endogenously controlled with breeding latitude as the decisive element pre‐determining the timing of annual events in our study populations.  相似文献   
44.
Phytochemistry Reviews - Cytokinins are plant hormones and play essential roles in regulating plant growth and development. They also have diverse pharmacological effects in animals and humans....  相似文献   
45.
The objective of our study was to compare the five different scoring methods of tumor‐infiltrating lymphocytes (TILs) assessment in a group of 213 cases of superficial spreading and nodular melanoma. The scoring methods include (a) Clark scoring; (b) Melanoma Institute Australia system; (c) scoring system used in the study of Saldanha et al.; (d) scoring system used in the TCGA study and modified by Park et al.; and (e) the system recently proposed by the “International Immuno‐Oncology Biomarker Working Group” for TILs scoring in all solid tumors. Prediction of survival with three main outcomes—disease‐specific‐free survival, local recurrence‐free survival, and distant metastasis‐free survival—was evaluated. The prognostic value of TILs showed statistical significance in univariate analysis regarding all three of the outcomes only for three of the five evaluated methods; the Clark scoring, the Melanoma Institute Australia system, and the system proposed by the “International Immuno‐Oncology Biomarker Working Group”. However, in multivariate analysis with covariants including Breslow thickness, type of melanoma, location, sex, and age, we did not find TILs to be an independent prognostic factor.  相似文献   
46.
47.
Ecosystems - Forest ecosystems worldwide are subjected to human-induced stressors, including eutrophication and acidification, and to natural disturbances (for example, insect infestation,...  相似文献   
48.
Extremophiles - The strain Pseudomonas aeruginosa san ai, isolated from an extreme environment (industrial mineral cutting oil, pH 10), is able to survive and persist in the presence of a variety...  相似文献   
49.
50.
BioControl - Nematodes of the genus Phasmarhabditis are facultative parasites of molluscs with a world-wide distribution but, so far, only one species P. hermaphrodita has been thoroughly studied...  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