全文获取类型
收费全文 | 2066篇 |
免费 | 204篇 |
国内免费 | 184篇 |
出版年
2024年 | 10篇 |
2023年 | 43篇 |
2022年 | 77篇 |
2021年 | 125篇 |
2020年 | 81篇 |
2019年 | 88篇 |
2018年 | 87篇 |
2017年 | 65篇 |
2016年 | 92篇 |
2015年 | 146篇 |
2014年 | 161篇 |
2013年 | 156篇 |
2012年 | 182篇 |
2011年 | 189篇 |
2010年 | 89篇 |
2009年 | 90篇 |
2008年 | 96篇 |
2007年 | 77篇 |
2006年 | 73篇 |
2005年 | 88篇 |
2004年 | 50篇 |
2003年 | 47篇 |
2002年 | 44篇 |
2001年 | 21篇 |
2000年 | 32篇 |
1999年 | 33篇 |
1998年 | 10篇 |
1997年 | 17篇 |
1996年 | 22篇 |
1995年 | 8篇 |
1994年 | 17篇 |
1993年 | 5篇 |
1992年 | 21篇 |
1991年 | 12篇 |
1990年 | 17篇 |
1989年 | 13篇 |
1988年 | 12篇 |
1987年 | 5篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有2454条查询结果,搜索用时 203 毫秒
991.
Seven p-terphenyl derivatives named terrestrins A-G together with three known ganbajunin B, thelephantins F and H, were isolated from the methanol extract of fruiting bodies of the Japanese inedible mushroom Thelephora terrestris (Thelephoraceae). Their structures were elucidated by means of high-resolution MS, 2D NMR, IR and UV spectroscopy, and X-ray crystallographic analysis. 相似文献
992.
Quang DN Hashimoto T Nomura Y Wollweber H Hellwig V Fournier J Stadler M Asakawa Y 《Phytochemistry》2005,66(7):797-809
Azaphilones, named cohaerins A and B were isolated from stromata of the xylariaceous ascomycete Hypoxylon cohaerens. Their absolute structures were determined by spectroscopic methods (2D NMR, MS, IR, UV CD), and subsequently confirmed by acetylation. Stromatal metabolite profiles of several taxa of Hypoxylon sect. Annulata were also generated using analytical HPLC with diode array and MS detection. The cohaerins were neither found in other Hypoxylon spp., nor in other Xylariaceae. However, they were present even in holotype material of H. cohaerens, collected over 200 years ago. The binaphthalene BNT was also omnipresent in sect Annulata, and its derivatives, the benzo[j]fluoranthenes daldinone A and truncatone, as well as presumably related compounds. These fungi were found devoid of other types of azaphilone pigments of the Xylariaceae, such as mitorubrins and daldinins, the latter of which are widespread in certain groups of Hypoxylon sect. Hypoxylon. Hence, chemotaxonomic data largely support the current generic concept. The original source of truncatone was identified as Hypoxylon annulatum. 相似文献
993.
Ligand-gated ion channels are transmembrane proteins that respond to a variety of transmitters, including acetylcholine, gamma-aminobutyric acid (GABA), glycine, and glutamate [1 and 2]. These proteins play key roles in neurotransmission and are typically found in the nervous system and at neuromuscular junctions [3]. Recently, acetylcholine receptor family members also have been found in nonneuronal cells, including macrophages [4], keratinocytes [5], bronchial epithelial cells [5], and endothelial cells of arteries [6]. The function of these channels in nonneuronal cells in mammals remains to be elucidated, though it has been shown that the acetylcholine receptor alpha7 subunit is required for acetylcholine-mediated inhibition of tumor necrosis factor release by activated macrophages [4]. We show that cup-4, a gene required for efficient endocytosis of fluids by C. elegans coelomocytes, encodes a protein that is homologous to ligand-gated ion channels, with the highest degree of similarity to nicotinic acetylcholine receptors. Worms lacking CUP-4 have reduced phosphatidylinositol 4,5-bisphosphate levels at the plasma membrane, suggesting that CUP-4 regulates endocytosis through modulation of phospholipase C activity. 相似文献
994.
Discovery-based science education: functional genomic dissection in Drosophila by undergraduate researchers
下载免费PDF全文
![点击此处可从《PLoS biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Chen J Call GB Beyer E Bui C Cespedes A Chan A Chan J Chan S Chhabra A Dang P Deravanesian A Hermogeno B Jen J Kim E Lee E Lewis G Marshall J Regalia K Shadpour F Shemmassian A Spivey K Wells M Wu J Yamauchi Y Yavari A Abrams A Abramson A Amado L Anderson J Bashour K Bibikova E Bookatz A Brewer S Buu N Calvillo S Cao J Chang A Chang D Chang Y Chen Y Choi J Chou J Datta S Davarifar A Desai P Fabrikant J Farnad S Fu K Garcia E Garrone N Gasparyan S Gayda P Goffstein C Gonzalez C Guirguis M 《PLoS biology》2005,3(2):e59
995.
Subunit composition of ATP-sensitive potassium channels in mitochondria of rat hearts 总被引:8,自引:0,他引:8
Cuong DV Kim N Joo H Youm JB Chung JY Lee Y Park WS Kim E Park YS Han J 《Mitochondrion》2005,5(2):121-133
Mitochondrial ATP-sensitive potassium (mitoKATP) channels play a pivotal role in early and late ischemic preconditioning, but the subunit composition of mitoKATP channels remains unclear. In this study, we investigated the subunit composition of mitoKATP channels in rat hearts using confocal microscopy, immunofluorescence, and Western blot analysis. The green fluorescent probe glibenclamide-BODIPY was colocalized with the red fluorescent mitochondrial marker MitroTracker Red in isolated ventricular myocytes and in ventricular myocyte mitochondria, indicating the presence of sulfonylurea receptors (SURs) in the mitochondria. Anti-Kir6.1, anti-Kir6.2, and anti-SUR2 immunofluorescence was colocalized with that of MitoTracker Red in isolated mitochondria, suggesting that Kir6.1, Kir6.2, and SUR2 subunits are present in the mitochondria. Similarly, Kir6.1 (approximately 46 kDa), Kir6.2 (approximately 46 and approximately 40 kDa), and SUR2 (approximately 140 kDa) proteins were found to be expressed in mitochondria using Western blot analysis. By contrast, SUR1 was not present in mitochondria. These results suggest that mitoKATP channels in rat hearts might comprise a combination of Kir6.1, Kir6.2, and SUR2 subunits. 相似文献
996.
Vi T. Dang Lexy H. Zhong Aric Huang Arlinda Deng Geoff H. Werstuck 《Metabolomics : Official journal of the Metabolomic Society》2018,14(7):92
Introduction
Three out of four people with diabetes will die of cardiovascular disease. However, the molecular mechanisms by which hyperglycemia promotes atherosclerosis, the major underlying cause of cardiovascular disease, are not clear.Objectives
Three distinct models of hyperglycemia-associated accelerated atherosclerosis were used to identify commonly altered metabolites and pathways associated with the disease.Methods
Normoglycemic apolipoprotein-E-deficient mice served as atherosclerotic control. Hyperglycemia was induced by multiple low-dose streptozotocin injections, or by introducing a point-mutation in one copy of insulin-2 gene. Glucosamine-supplemented mice, which experience accelerated atherosclerosis to a similar extent as hyperglycemia-induced models without alterations in glucose or insulin levels, were also included in the analysis. Untargeted plasma metabolomics were used to investigate hyperglycemia-associated accelerated atherosclerosis in three disease models. The effect of specific significantly altered metabolites on pro-atherogenic processes was investigated in cultured human vascular cells.Results
Hyperglycemic and glucosamine-supplemented mice showed distinct metabolomic profiles compared to controls. Meta-analysis of three disease models revealed 62 similarly altered metabolite features (FDR-adjusted p?<?0.05). Identification of shared metabolites revealed alterations in glycerophospholipid and sphingolipid metabolism, and pro-atherogenic processes including inflammation and oxidative stress. Post-multivariate and pathway analyses indicated that the glycosphingolipid pathway is strongly associated with hyperglycemia-induced accelerated atherosclerosis in these atherogenic mouse models. Glycosphingolipids induced oxidative stress and inflammation in cultured human vascular cells.Conclusion
Glycosphingolipids are strongly associated with hyperglycemia-induced accelerated atherosclerosis in three distinct models. They also promote pro-atherogenic processes in cultured human cells. These results suggest glycosphingolipid pathway may be a potential therapeutic target to block or slow atherogenesis in diabetic patients.997.
998.
新疆裸果木亚科植物花粉形态学研究 总被引:10,自引:1,他引:9
通过光镜和扫镜电镜对新疆产裸果木亚科3属6种植物的花粉形态进行了观察与观察。结果表明:花粉形态有三种类型,裸果木属为散孔类型,治疝草属为三孔类型,拟漆姑草属为三沟类型。具孔类型中,萌发孔边缘界限有不清楚,孔膜不明显,颗粒状纹饰;具沟类型中,萌发沟上有膜覆盖,具颗粒状纹饰。根据花粉形态,编出分属检索表,并讨论了花粉形态在分类中的作用以及各属之间的亲缘关系。 相似文献
999.
1000.