全文获取类型
收费全文 | 947篇 |
免费 | 62篇 |
出版年
2022年 | 13篇 |
2021年 | 18篇 |
2020年 | 12篇 |
2019年 | 20篇 |
2018年 | 26篇 |
2017年 | 25篇 |
2016年 | 31篇 |
2015年 | 46篇 |
2014年 | 68篇 |
2013年 | 59篇 |
2012年 | 83篇 |
2011年 | 83篇 |
2010年 | 36篇 |
2009年 | 39篇 |
2008年 | 52篇 |
2007年 | 52篇 |
2006年 | 35篇 |
2005年 | 39篇 |
2004年 | 46篇 |
2003年 | 26篇 |
2002年 | 19篇 |
2001年 | 19篇 |
2000年 | 24篇 |
1999年 | 10篇 |
1998年 | 16篇 |
1997年 | 10篇 |
1996年 | 3篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1971年 | 2篇 |
1968年 | 3篇 |
1966年 | 3篇 |
1892年 | 2篇 |
1889年 | 3篇 |
1888年 | 2篇 |
1882年 | 2篇 |
1879年 | 3篇 |
排序方式: 共有1009条查询结果,搜索用时 109 毫秒
971.
Fenna M. Krienen B. T. Thomas Yeo Randy L. Buckner 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2014,369(1653)
Functional coupling across distributed brain regions varies across task contexts, yet there are stable features. To better understand the range and central tendencies of network configurations, coupling patterns were explored using functional MRI (fMRI) across 14 distinct continuously performed task states ranging from passive fixation to increasingly demanding classification tasks. Mean global correlation profiles across the cortex ranged from 0.69 to 0.82 between task states. Network configurations from both passive fixation and classification tasks similarly predicted task coactivation patterns estimated from meta-analysis of the literature. Thus, even across markedly different task states, central tendencies dominate the coupling configurations. Beyond these shared components, distinct task states displayed significant differences in coupling patterns in response to their varied demands. One possibility is that anatomical connectivity provides constraints that act as attractors pulling network configurations towards a limited number of robust states. Reconfigurable coupling modes emerge as significant modifications to a core functional architecture. 相似文献
972.
Stephen P Page Troy Watts Wee Tiong Yeo Dhinoja Mehul 《Indian pacing and electrophysiology journal》2014,14(4):203-210
This report describes a patient presenting with a narrow complex tachycardia in the context of prior myocardial infarction and impaired ventricular function. Electrophysiological studies confirmed ventricular tachycardia and activation and entrainment mapping demonstrated a critical isthmus within an area of scar involving the His-Purkinje system accounting for the narrow QRS morphology. This very rare case shares some similarities with upper septal ventricular tachycardia seen in patients with structurally normal hearts, but to our knowledge has not been seen previously in patients with ischemic heart disease. 相似文献
973.
South American freshwater stingrays of the family Potamotrygonidae have long been popular worldwide as ornamentals in the
aquarium trade. Despite this, there have so far not been any reported cases of their establishment elsewhere in the world.
Here, we document the ocellate river stingray, Potamotrygon motoro, as having established itself in Singapore. This represents the first alien record of a South American freshwater stingray
outside the Neotropics. 相似文献
974.
975.
976.
977.
978.
979.
Yeo Hyunjin Ahn Sung Shin Lee Young Han Shin Soon Young 《Molecular biology reports》2020,47(8):5953-5962
Molecular Biology Reports - Pro-opiomelanocortin (POMC) is a large precursor protein of and β-endorphin. POMC expressed in keratinocytes regulates various pathophysiological responses, such as... 相似文献
980.
The Western Ghats mountain range in India is a biodiversity hotspot for a variety of organisms including a large number of endemic freshwater crab species and genera of the family Gecarcinucidae. The phylogenetic relationships of these taxa, however, have remained poorly understood. Here, we present a phylogeny that includes 90% of peninsular Indian genera based on mitochondrial 16S rRNA and nuclear histone H3 gene sequences. The subfamily Gecarcinucinae was found to be paraphyletic with members of two other subfamilies, Liotelphusinae and Parathelphusinae, nesting within. We identify a well‐supported clade consisting of north Indian species and one clade comprising mostly south Indian species that inhabit the southern ‘sky islands’ of the Western Ghats. Relationships of early diverging genera, however, were resolved with low support. This study also includes newly sampled material from an isolated mountain plateau in the northern part of the Western Ghats, representing a new species of Gubernatoriana, which we describe here as Gubernatoriana basalticola sp. n. The new species is immediately distinguished from its congeners and the related genera Ghatiana and Inglethelphusa by its carapace and cheliped morphology, which are unique among Indian freshwater crabs. This study highlights the urgent need for continued faunistic studies to assess the true diversity of gecarcinucid crabs on the Indian subcontinent, to fully understand the basal phylogenetic relationships within the freshwater crab family Gecarcinucidae, and to evaluate the conservation threat status and biogeography of the montane freshwater crabs of the Western Ghats. 相似文献