全文获取类型
收费全文 | 105篇 |
免费 | 5篇 |
国内免费 | 14篇 |
专业分类
124篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 5篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 5篇 |
2012年 | 5篇 |
2011年 | 6篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 5篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 4篇 |
2002年 | 8篇 |
2001年 | 11篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 4篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有124条查询结果,搜索用时 11 毫秒
1.
记述产于新疆的我国皿蛛科微蛛亚科2新纪录属:双舟蛛属Dicymbium Mcnge 1867和长插蛛属Silometopus Simon 1926,2新纪录种:黑双舟蛛Dicymbium nigrum(Blackwall,1834)和罗氏长插蛛Silometopus reussi(Thorell,1871)。 相似文献
2.
Kosteletzkya virginica (K. virginica) is used for revegetation of salt-affected coastal tidal flats and as a raw material
of biodiesel. K. virginica root tuber, a biowaste with low economic value, is rich in bioactive compounds. This
study aimed to extract and identify flavonoids from K. virginica root tubers. The optimal extraction conditions
were 1/25 (w/v) solid/liquid ratio, 40% ethanol concentration at 40°C for 60 min. Under these conditions,
65.2 ± 3.7 mg/g total flavonoid content was extracted from the roots, which were collected from salinized soil
in late autumn of the third year. Antioxidant activity was evaluated through 1,1-diphenyl-2-picrylhydrazyl,
hydroxyl radical, and superoxide anion scavenging assays. The extracted flavonoids exhibited antioxidant activity
in a dose-dependent manner. Five flavonoids, glucoliquiritin apioside, licoisoflavone B, 5-methoxy-7,8-diprenyl-
flavone, 7,2′-dihydroxy-6,8-dimethyl-4′,5′-methylenedioxyflavan, and 5,7,4′-trihydroxy-3′-methoxy-6,8-di-Cmethylflavanone, were identified by ultra-performance liquid chromatography–tandem mass spectrometry.
Our results suggest that the flavonoids of K. virginica root tubers might be potent antioxidants and can be effectively applied as an ingredient in food and natural medicine. 相似文献
3.
本文介绍用二相分配法制备蚕豆叶片原生质膜上的Ca~(2+)·Mg~(2+)-ATPase,用以研究镧系,稀土离子对此酶活性的影响。初步证实Pr~(3+)、Nd~(3+)对依赖于CaM的以及不依赖于CaM的蚕豆叶片原生质膜上Ca~(2+)·Mg~(2+)-ATPase活性的抑制不是CaM专一的。 相似文献
4.
1 前言 土地处理系统对悬浮固体具有很好的净化效果,其净化率要害99%以上,但实际过程中,一些干扰 相似文献
5.
不同生态环境对蒲公英超氧物歧化酶(SOD)的影响 总被引:6,自引:1,他引:5
选择干生,湿生,阳生,阴生四种生境中生长的蒲公英Taraxacum mongolicum Hand.-Mazz分根,叶,花分别测定了SOD活性和比活性,并比较了同工酶谱的变化情况,结果表明不同生境未能改变SOD的同工酶条带数,但对其活性大小有影响,这种影响尤其表现在根上,湿生和阴生根的SOD活性明显高于干生和阳生根的SOD活性,显示出蒲公英的不同器官适应不同的环境效应。 相似文献
6.
Zai Hang Zhang Xin Yu Jia Jing Yi Fang Hao Chai Qun Huang Chang She Peng Jia De Chun Geng Wei Xu 《Journal of cellular and molecular medicine》2020,24(7):4233-4244
The increase in bone resorption and/or the inhibition of bone regeneration caused by wear particles are the main causes of periprosthetic osteolysis. The SOST gene and Sclerostin, a protein synthesized by the SOST gene, are the characteristic marker of osteocytes and regulate bone formation and resorption. We aimed to verify whether the SOST gene was involved in osteolysis induced by titanium (Ti) particles and to investigate the effects of SOST reduction on osteolysis. The results showed osteolysis on the skull surface with an increase of sclerostin levels after treated with Ti particles. Similarly, sclerostin expression in MLO-Y4 osteocytes increased when treated with Ti particles in vitro. After reduction of SOST, local bone mineral density and bone volume increased, while number of lytic pores on the skull surface decreased and the erodibility of the skull surface was compensated. Histological analyses revealed that SOST reduction increased significantly alkaline phosphatase- (ALP) and osterix-positive expression on the skull surface which promoted bone formation. ALP activity and mineralization of MC3T3-E1 cells also increased in vitro when SOST was silenced, even if treated with Ti particles. In addition, Ti particles decreased β-catenin expression with an increase in sclerostin levels, in vivo and in vitro. Inversely, reduction of SOST expression increased β-catenin expression. In summary, our results suggested that reduction of SOST gene can activate the Wnt/β-catenin signalling pathway, promoting bone formation and compensated for bone loss induced by Ti particles. Thus, this study provided new perspectives in understanding the mechanisms of periprosthetic osteolysis. 相似文献
7.
目的探讨早产儿肠道微生态变化及其与胎龄、出生体质量的关系。方法选取2018年5月至2020年5月我院收治的80例早产儿作为早产组,同期收治的80例足月新生儿作为对照组。收集入组新生儿出生后3 d、3周的粪便,比较2组研究对象粪便标本中细菌丰富度和Shannon Wiener指数;根据早产组胎龄和出生体质量不同分组,分析胎龄、出生体质量与肠道微生态变化的关系。结果(1)出生3 d,早产组新生儿粪便标本的DGGE图谱条带数、Shannon Wiener指数均显著低于对照组(t=3.179、3.521,均P<0.05);(2)出生3 d,胎龄34+1~36+6周组新生儿粪便标本的DGGE图谱条带数、Shannon Wiener指数显著高于28~30周组、30+1~32周组和32+1~34周组(q=9.653、6.476、4.848和8.796、8.008、6.277,均P<0.05);(3)出生3 d,体质量>2 000 g组新生儿粪便标本的的DGGE图谱条带数、Shannon Wiener指数显著高于≤1 500 g组(q=5.601和4.593,均P<0.05);(4)不同出生体质量、胎龄的早产儿,出生3周粪便标本的DGGE图谱条带数、Shannon Wiener指数相比差异无统计学意义(F=1.577和2.326,均P>0.05)。结论与足月新生儿相比,早产儿出生后细菌定植出现延迟且多样性差,胎龄越小、出生体质量越低的早产儿的肠道菌群的多样性更低、定植延迟的可能性更大,出生3周后其肠道微生态逐渐恢复正常。 相似文献
8.
9.
10.
Shuwan Zai Ruijie Han Wangen Zhao Chuang Ma Wenliang Huang Shengzhong Liu 《Liver Transplantation》2024,14(1):2303264
Defects within perovskite have been known to act as the nonradiative recombination centers, negatively impacting the carrier transport, which degrades the photovoltaic performance of perovskite solar cells (PSCs). Therefore, preparing a high-quality perovskite film is of vital significance. To this end, a room-temperature molten salt, dimethylamine formate (DMAFa), is introduced into perovskite precursor solution to regulate the crystallization process of CsPbI3 films. DMAFa can coordinate with Pb2+ as HCOO−-Pb2+ in the early stages, then HCOO−-Pb2+ is gradually displaced by I−-Pb2+ due to its decomposition during the subsequent annealing, thus delaying the crystallization rate, meanwhile, the DMA+ can interact with the uncoordinated Pb2+ to passivate defects of perovskite films, thereby, forming a high-quality CsPbI3 film with large grain size and low-defect density. As a result of this strategy, the power conversion efficiency is increased to 20.40%, and the open-circuit voltage is up to 1.21 V. These findings indicate that the introduction of DMAFa offers a fundamental way to achieve high-performance CsPbI3 PSCs. 相似文献