全文获取类型
收费全文 | 635篇 |
免费 | 30篇 |
国内免费 | 2篇 |
专业分类
667篇 |
出版年
2023年 | 2篇 |
2022年 | 11篇 |
2021年 | 14篇 |
2020年 | 8篇 |
2019年 | 7篇 |
2018年 | 12篇 |
2017年 | 12篇 |
2016年 | 20篇 |
2015年 | 39篇 |
2014年 | 38篇 |
2013年 | 39篇 |
2012年 | 55篇 |
2011年 | 47篇 |
2010年 | 31篇 |
2009年 | 31篇 |
2008年 | 43篇 |
2007年 | 42篇 |
2006年 | 37篇 |
2005年 | 37篇 |
2004年 | 28篇 |
2003年 | 26篇 |
2002年 | 25篇 |
2001年 | 11篇 |
2000年 | 16篇 |
1999年 | 10篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有667条查询结果,搜索用时 0 毫秒
51.
Neuroprotection by methanol extract of Uncaria rhynchophylla against global cerebral ischemia in rats 总被引:3,自引:0,他引:3
Suk K Kim SY Leem K Kim YO Park SY Hur J Baek J Lee KJ Zheng HZ Kim H 《Life sciences》2002,70(21):2467-2480
In traditional Oriental medicine, Uncaria rhynchophylla has been used to lower blood pressure and to relieve various neurological symptoms. However, scientific evidence related to its effectiveness or precise modes of action has not been available. Thus, in the current study, we evaluated neuroprotective effects of U. rhynchophylla after transient global ischemia using 4-vessel occlusion model in rats. Methanol extract of U. rhynchophylla administered intraperitoneally (100-1000 mg/kg at 0 and 90 min after reperfusion) significantly protected hippocampal CA1 neurons against 10 min transient forebrain ischemia. Measurement of neuronal cell density in CA1 region at 7 days after ischemia by Nissl staining revealed more than 70% protection in U. rhynchophylla-treated rats compared to saline-treated animals. In U. rhynchophylla-treated animals, induction of cyclooxygenase-2 in hippocampus at 24 hr after ischemia was significantly inhibited at both mRNA and protein levels. Furthermore, U. rhynchophylla extract inhibited TNF-alpha and nitric oxide production in BV-2 mouse microglial cells in vitro. These anti-inflammatory actions of U. rhynchophylla extract may contribute to its neuroprotective effects. 相似文献
52.
Eyal Ben‐Hur Ori Fragman‐Sapir Rivka Hadas Alon Singer Ronen Kadmon 《Ecology letters》2012,15(11):1276-1282
Functional trade‐offs have long been recognised as important mechanisms of species coexistence, but direct experimental evidence for such mechanisms is extremely rare. Here, we test the effect of one classical trade‐off – a negative correlation between seed size and seed number – by establishing microcosm plant communities with positive, negative and no correlation between seed size and seed number and analysing the effect of the seed size/number correlation on species richness. Consistent with theory, a negative correlation between seed size and seed number led to a higher number of species in the communities and a corresponding wider range of seed size (a measure of functional richness) by promoting coexistence of large‐ and small‐seeded species. Our study provides the first direct evidence that a seed size/number trade‐off may contribute to species coexistence, and at a wider context, demonstrates the potential role of functional trade‐offs in maintaining species diversity. 相似文献
53.
Antiangiogenic properties of cafestol, a coffee diterpene, in human umbilical vein endothelial cells
Wang S Yoon YC Sung MJ Hur HJ Park JH 《Biochemical and biophysical research communications》2012,421(3):567-571
As angiogenesis plays important roles in tumor growth and metastasis, searching for antiangiogenic compounds is a promising tactic for treating cancers. Cafestol, a diterpene found mainly in unfiltered coffee, provides benefit through varied biological activity, including antitumorigenic, antioxidative, and anti-inflammatory effects. This study aimed to investigate the effects of cafestol on angiogenesis and to uncover the associated mechanism. We show that cafestol inhibits angiogenesis of human umbilical vascular endothelial cells. This inhibition affects the following specific steps of the angiogenic process: proliferation, migration, and tube formation. The inhibitory effects of cafestol are accompanied by decreasing phosphorylation of FAK and Akt and by a decrease in nitric oxide production. Overall, cafestol inhibits angiogenesis by affecting the angiogenic signaling pathway. 相似文献
54.
Hur JS Harada H Oh SO Lim KM Kang ES Lee SM Kahng HY Kim HW Jung JS Koh YJ 《Journal of microbiology (Seoul, Korea)》2004,42(2):163-167
After an overview on the temporary situation of the lichenology in South Korea, localities of 95 macrolichen taxa are reported for South Korea. In this revised lichen flora of South Korea, 16 species are apparently new to the territory. Voucher specimens have been deposited in the Korean Lichen Research Institute (KoLRI) at Sunchon National University in Korea, and duplicates have also been donated to the National History Museum and Institute, in Chiba, (CBM) Japan. 相似文献
55.
56.
57.
58.
Won Cheol Yim Mia L Swain Dongna Ma Hong An Kevin A Bird David D Curdie Samuel Wang Hyun Don Ham Agusto Luzuriaga-Neira Jay S Kirkwood Manhoi Hur Juan K Q Solomon Jeffrey F Harper Dylan K Kosma David Alvarez-Ponce John C Cushman Patrick P Edger Annaliese S Mason J Chris Pires Haibao Tang Xingtan Zhang 《The Plant cell》2022,34(11):4143
59.
Hui Du Sunghan Kim Yoon-Sun Hur Myung-Sok Lee Suk-Ha Lee Choong-Ill Cheon 《Molecules and cells》2015,38(2):187-194
Thioredoxin (TRX) is a disulfide reductase present ubiquitously in all taxa and plays an important role as a regulator of cellular redox state. Recently, a redox-independent, chaperone function has also been reported for some thioredoxins. We previously identified nodulin-35, the subunit of soybean uricase, as an interacting target of a cytosolic soybean thioredoxin, GmTRX. Here we report the further characterization of the interaction, which turns out to be independent of the disulfide reductase function and results in the co-localization of GmTRX and nodulin-35 in peroxisomes, suggesting a possible function of GmTRX in peroxisomes. In addition, the chaperone function of GmTRX was demonstrated in in vitro molecular chaperone activity assays including the thermal denaturation assay and malate dehydrogenase aggregation assay. Our results demonstrate that the target of GmTRX is not only confined to the nodulin-35, but many other peroxisomal proteins, including catalase (AtCAT), transthyretin-like protein 1 (AtTTL1), and acyl-coenzyme A oxidase 4 (AtACX4), also interact with the GmTRX. Together with an increased uricase activity of nodulin-35 and reduced ROS accumulation observed in the presence of GmTRX in our results, especially under heat shock and oxidative stress conditions, it appears that GmTRX represents a novel thioredoxin that is co-localized to the peroxisomes, possibly providing functional integrity to peroxisomal proteins. 相似文献
60.
This study developed biomechanical models for hand breakaway strength that account for not only grip force but also hand-handle frictional coupling in generation of breakaway strength. Specifically, models for predicting breakaway strength for two commonly-used handle shapes (circular and rectangular handles) and varying coefficients of friction (COF) between the hand and handle were proposed. The models predict that (i) breakaway strength increases with increasing COF and (ii) a circular handle with a 50.8 mm-diameter results in greater mean breakaway strength than a handle with a rectangular cross-section of 38.1 by 38.1 mm for COFs greater than 0.42. To test these model predictions, breakaway strengths of thirteen healthy young adults were measured for three frequently-encountered COF conditions (represented by three glove types of polyester (COF=0.32), bare hand (COF=0.50), and latex (COF=0.74) against an aluminum handle) and for the two handle shapes. Consistent with the model predictions, mean breakaway strength increased with increasing COF and was greater for the circular than rectangular handle for COFs of 0.50 and 0.74. Examination of breakaway strength normalized to body weight reveals that modification of COF and handle shapes could influence whether one can hold his/her body using the hands or not (thus must fall), highlighting the importance of considering these parameters for fall prevention. The biomechanical models developed herein have the potential to be applied to general handle shapes and COF conditions. These models can be used to optimize handle design to maximize breakaway strength and minimize injuries due to falls from ladders or scaffolds. 相似文献