全文获取类型
收费全文 | 926篇 |
免费 | 88篇 |
出版年
2023年 | 2篇 |
2021年 | 4篇 |
2020年 | 9篇 |
2019年 | 18篇 |
2018年 | 18篇 |
2017年 | 15篇 |
2016年 | 24篇 |
2015年 | 29篇 |
2014年 | 36篇 |
2013年 | 45篇 |
2012年 | 61篇 |
2011年 | 64篇 |
2010年 | 36篇 |
2009年 | 34篇 |
2008年 | 45篇 |
2007年 | 58篇 |
2006年 | 62篇 |
2005年 | 57篇 |
2004年 | 56篇 |
2003年 | 40篇 |
2002年 | 51篇 |
2001年 | 23篇 |
2000年 | 24篇 |
1999年 | 23篇 |
1998年 | 15篇 |
1997年 | 10篇 |
1996年 | 7篇 |
1995年 | 12篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 17篇 |
1991年 | 18篇 |
1990年 | 11篇 |
1989年 | 6篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1978年 | 3篇 |
1976年 | 6篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 5篇 |
1971年 | 2篇 |
1929年 | 1篇 |
1928年 | 2篇 |
排序方式: 共有1014条查询结果,搜索用时 15 毫秒
1.
Michael Andrew Pest Courtney Alice Pest Melina Rodrigues Bellini Qingping Feng Frank Beier 《PloS one》2015,10(11)
Background
Osteoarthritis (OA) is a degenerative joint disease with poorly understood etiology and pathobiology. Mitogen activated protein kinases (MAPKs) including ERK and p38 play important roles in the mediation of downstream pathways involved in cartilage degenerative processes. Dual specificity phosphatase 1 (DUSP1) dephosphorylates the threonine/serine and tyrosine sites on ERK and p38, causing deactivation of downstream signalling. In this study we examined the role of DUSP1 in spontaneous OA development at 21 months of age using a genetically modified mouse model deficient in Dusp1 (DUSP1 knockout mouse).Results
Utilizing histochemical stains of paraffin embedded knee joint sections in DUSP1 knockout and wild type female and male mice, we showed similar structural progression of cartilage degeneration associated with OA at 21 months of age. A semi-quantitative cartilage degeneration scoring system also demonstrated similar scores in the various aspects of the knee joint articular cartilage in DUSP1 knockout and control mice. Examination of overall articular cartilage thickness in the knee joint demonstrated similar results between DUSP1 knockout and wild type mice. Immunostaining for cartilage neoepitopes DIPEN, TEGE and C1,2C was similar in the cartilage lesion sites and chondrocyte pericellular matrix of both experimental groups. Likewise, immunostaining for phosphoERK and MMP13 showed similar intensity and localization between groups. SOX9 immunostaining demonstrated a decreased number of positive cells in DUSP1 knockout mice, with correspondingly decreased staining intensity. Analysis of animal walking patterns (gait) did not show a discernable difference between groups.Conclusion
Loss of DUSP1 does not cause changes in cartilage degeneration and gait in a mouse model of spontaneous OA at 21 months of age. Altered staining was observed in SOX9 immunostaining which may prove promising for future studies examining the role of DUSPs in cartilage and OA, as well as models of post-traumatic OA. 相似文献2.
Stan D. Wullschleger Amy L. Breen Colleen M. Iversen Matthew S. Olson Torgny Näsholm Ulrika Ganeteg Matthew D. Wallenstein David J. Weston 《Molecular ecology》2015,24(10):2301-2309
Molecular ecology is poised to tackle a host of interesting questions in the coming years. The Arctic provides a unique and rapidly changing environment with a suite of emerging research needs that can be addressed through genetics and genomics. Here we highlight recent research on boreal and tundra ecosystems and put forth a series of questions related to plant and microbial responses to climate change that can benefit from technologies and analytical approaches contained within the molecular ecologist's toolbox. These questions include understanding (i) the mechanisms of plant acquisition and uptake of N in cold soils, (ii) how these processes are mediated by root traits, (iii) the role played by the plant microbiome in cycling C and nutrients within high‐latitude ecosystems and (iv) plant adaptation to extreme Arctic climates. We highlight how contributions can be made in these areas through studies that target model and nonmodel organisms and emphasize that the sequencing of the Populus and Salix genomes provides a valuable resource for scientific discoveries related to the plant microbiome and plant adaptation in the Arctic. Moreover, there exists an exciting role to play in model development, including incorporating genetic and evolutionary knowledge into ecosystem and Earth System Models. In this regard, the molecular ecologist provides a valuable perspective on plant genetics as a driver for community biodiversity, and how ecological and evolutionary forces govern community dynamics in a rapidly changing climate. 相似文献
3.
4.
Baiba Jansone Inga Kadish Thomas van Groen Ulrika Beitnere Doyle Ray Moore Aiva Plotniece Karlis Pajuste Vija Klusa 《PloS one》2015,10(6)
Ca2+ blockers, particularly those capable of crossing the blood-brain barrier (BBB), have been suggested as a possible treatment or disease modifying agents for neurodegenerative disorders, e.g., Alzheimer’s disease. The present study investigated the effects of a novel 4-(N-dodecyl) pyridinium group-containing 1,4-dihydropyridine derivative (AP-12) on cognition and synaptic protein expression in the brain. Treatment of AP-12 was investigated in wild type C57BL/6J mice and transgenic Alzheimer’s disease model mice (Tg APPSweDI) using behavioral tests and immunohistochemistry, as well as mass spectrometry to assess the blood-brain barrier (BBB) penetration. The data demonstrated the ability of AP-12 to cross the BBB, improve spatial learning and memory in both mice strains, induce anxiolytic action in transgenic mice, and increase expression of hippocampal and cortical proteins (GAD67, Homer-1) related to synaptic plasticity. The compound AP-12 can be seen as a prototype molecule for use in the design of novel drugs useful to halt progression of clinical symptoms (more specifically, anxiety and decline in memory) of neurodegenerative diseases, particularly Alzheimer’s disease. 相似文献
5.
6.
7.
8.
9.
10.
Geijer Paulina Peterson Sindra Härndahl Ulrika Styring Stenbjörn Sundby Cecilia 《Photosynthesis research》1998,58(3):231-243
The Photosystem II multisubunit protein complex can be extracted from thylakoid membranes with non-ionic detergents and subjected to various spectroscopical and biochemical investigations. This paper shows that after extraction with dodecyl--D-maltoside, several Photosystem II complexes could be resolved by isoelectric focusing. Structurally, the various Photosystem II complexes differed from each other in polypeptide composition, especially with regard to the chlorophyll a/b-binding proteins, which gave rise to differing isoelectric points. Functionally, the various Photosystem II complexes differed from each other on the acceptor side, as judged by acceptor side-dependent electron transfer and electron paramagnetic resonance (EPR). The QA
- Fe2+-signal (g = 1.84), arising from QA
- spin-coupled to the acceptor-side iron, and a radical signal arising from decoupled QA
- (g = 2.0045) could be detected simultaneously in some of the Photosystem II complexes, and the amount of each of the two signals were inversely related. The results are discussed in relation to previously known heterogeneities in Photosystem II. 相似文献