全文获取类型
收费全文 | 66篇 |
免费 | 2篇 |
国内免费 | 2篇 |
专业分类
化学 | 42篇 |
力学 | 5篇 |
综合类 | 1篇 |
数学 | 2篇 |
物理学 | 20篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 7篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 5篇 |
2013年 | 3篇 |
2011年 | 2篇 |
2010年 | 2篇 |
2009年 | 6篇 |
2008年 | 4篇 |
2007年 | 2篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2004年 | 5篇 |
2002年 | 1篇 |
2001年 | 2篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1987年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有70条查询结果,搜索用时 15 毫秒
61.
日蒸发率是评价高真空多层绝热杜瓦保冷性能最重要的技术参数。该文对日蒸发率的影响因素进行了总结,重点介绍了储存压力和环境温度对日蒸发率的影响。以充满率为90%的210L小型杜瓦为例,测试了日蒸发率的变化规律。结果表明,杜瓦的日蒸发率与储存压力成正比,同时日蒸发率的波动随着储存压力的升高而增大,且环境温度对日蒸发率的影响出现延迟。 相似文献
62.
高效液相色谱法研究邻烯丙基苯酚在小麦植株中的向基传导和分布 总被引:2,自引:0,他引:2
采用一种快速、灵敏的高效液相色谱-二极管阵列检测器法(HPLC-DAD)研究拟银杏杀菌剂邻烯丙基苯酚在小麦幼苗中的自顶向基传导作用,并定量分析其进入小麦植株后的具体分布。HPLC-DAD检测条件为:等度流动相65%乙腈/水(0.1%醋酸),HYPERSIL BDS C18,5μm,250 mm×4.6 mm i.d色谱柱,检测波长280 nm。邻烯丙基苯酚的线性回归方程为Y=8.0266X 5.019(r=0.9999),在2~500 mg/L浓度范围内线性关系良好。日内与日间精密度均≤12.44%;平均回收率为83.55%;最低检出限为1.5 ng,最低定量限为2 mg/L。分析方法符合小麦体内药物含量测定的要求。经HPLC-DAD检测,确证了邻烯丙基苯酚具有自小麦叶部向基部传导的特性,施药4h后即可传至根部。给药处理72 h后药剂在小麦叶、茎及根部的积累水平相当,基本完成自顶向基传导过程。 相似文献
63.
64.
65.
嘉兴电厂二期取水工程位于海象条件异常复杂的杭州湾海域,工程采用海上浮运沉放的工艺进行施工,其中取水头为外径25m,高16.6m,空气中重约4700T的圆桶形结构,结构偏心、重心高、稳定性差,对海上浮运沉放施工极为不利。针对取水头起浮、海上浮运和加水下沉的各个阶段的进行稳定性分析,为确定最优的吊沉方案,确保取水头精确就位提供理论依据,成果也可为其它类似工程提供借鉴与参考。 相似文献
66.
67.
Jong-Yun Noh Dong-Hee Han Mi-Hee Kim Il-Gyu Ko Sung-Eun Kim Noheon Park Han Kyoung Choe Khae-Hawn Kim Kyungjin Kim Chang-Ju Kim Sehyung Cho 《Experimental & molecular medicine》2014,46(3):e81
Circadian clocks are the endogenous oscillators that harmonize a variety of physiological processes within the body. Although many urinary functions exhibit clear daily or circadian variation in diurnal humans and nocturnal rodents, the precise mechanisms of these variations are as yet unclear. In the present study, we demonstrate that Per2 promoter activity clearly oscillates in neonate and adult bladders cultured ex vivo from Per2::Luc knock-in mice. In subsequent experiments, we show that multiple local oscillators are operating in all the bladder tissues (detrusor, sphincter and urothelim) and the lumbar spinal cord (L4–5) but not in the pontine micturition center or the ventrolateral periaqueductal gray of the brain. Accordingly, the water intake and urine volume exhibited daily and circadian variations in young adult wild-type mice but not in Per1−/−Per2−/− mice, suggesting a functional clock-dependent nature of the micturition rhythm. Particularly in PDK mice, the water intake and urinary excretion displayed an arrhythmic pattern under constant darkness, and the amount of water consumed and excreted significantly increased compared with those of WT mice. These results suggest that local circadian clocks reside in three types of bladder tissue and the lumbar spinal cord and may have important roles in the circadian control of micturition function. 相似文献
68.
磷脂酰乙醇是具有潜在临床应用价值的酒精摄入生物学标志物,准确测定其含量可以为酒精摄入监测提供客观、量化的重要参考依据。本研究建立了一种基于智能化分时区间采集技术的液相色谱-串联质谱分析方法,能够同时实现对人全血样品中18种磷脂酰乙醇的准确测定。采用甲醇-甲基叔丁基醚-水作为萃取体系,选用XBridge C18色谱柱,以2.5 mmol/L乙酸铵异丙醇溶液和2.5 mmol/L乙酸铵水溶液-乙腈(50∶50, v/v)为流动相进行梯度洗脱,采用电喷雾离子源、智能化分时间段-负离子多反应选择离子监测模式。经验证,该方法线性关系良好,相关系数≥0.9998,线性范围在10~2500 ng/mL之间,检出限和定量限分别为0.7~2.8 ng/mL、2.2~9.4 ng/mL,加标回收率在91.0%~102.2%之间,日内精密度和日间精密度在0.4%~7.4%之间。该方法简便、快速、精密,智能化分时区间采集方法为每个离子通道分配合适的扫描时间段,增加了每个目标物离子通道的有效采集时长,提高了各目标分析物的信号响应,从而实现了对人全血样本中18种磷脂酰乙醇的有效分析测定。使用本方法测定了359名有规律饮酒习惯的志愿者全血样本,样本中的总磷脂酰乙醇含量范围为51.13 ng/mL~2.89 μg/mL,平均为363.16 ng/mL。磷脂酰乙醇16∶0/18∶1、16∶0/18∶2是两个丰度最大的同系物,平均含量分别为74.21和48.75 ng/mL,各约占总量的20.43%和13.42%。Spearman相关性分析结果显示,磷脂酰乙醇之间相关性良好,并与临床现有酒精生物学标志物γ-谷氨酰转肽酶呈正相关;同时磷脂酰乙醇与肝肾功能相关临床生化指标显著相关。所建方法可以准确、精密检测人血磷脂酰乙醇含量,能够客观、可靠、量化反映人体酒精摄入状况,并可为临床酒精摄入监测提供有潜在应用价值的分析手段。 相似文献
69.
70.
Xiaojia Su Ruirui Shi Haiyan Hu Linfeng Hu Qichao Wei Yuanyuan Guan Jingling Chang Chengwei Li 《Molecules (Basel, Switzerland)》2022,27(21)
Ginkgo tea and ginkgo wine are two familiar Ginkgo biloba leaf extract (GBE) drinks in the form of dietary supplements (DS) used for healthcare in east Asia. Nevertheless, a comprehensive evaluation of their safety and efficacy is still lacking. In this study, GBE drinks were prepared from naturally newly senescent yellow leaves (YL) and green leaves (GL) in autumn. Their total flavonoids, antioxidant capacity and prescribed ingredients were investigated. In brief, the proportions of total flavonoids, total flavonol glycosides (TFs), total terpene trilactones (TTLs) and ginkgolic acids in the GBE drinks all did not meet the standards of worldwide pharmacopoeias. Specifically, the levels of TFs in the ginkgo tea prepared from YL were significantly higher than that prepared from GL. Further analyses revealed a substandard ratio of isorhamnetin/quercetin and an accumulation of leaf-age-related compounds, which were both unqualified. The proportions of specific TTLs varied between the ginkgo tea and ginkgo wine, although no significant differences were detected in terms of the total levels of TTLs. Noticeably, numerous biflavones and thousands of times over the limiting concentration of ginkgolic acids, including newly identified types, were only detected in ginkgo wine. Finally, the use of the GBE drinks as DSs was comprehensively evaluated according to the acceptable daily intake. This study showed the limited healthcare effects of GBE drinks despite their powerful antioxidant capacity. 相似文献