全文获取类型
收费全文 | 4926篇 |
免费 | 304篇 |
国内免费 | 2篇 |
专业分类
5232篇 |
出版年
2024年 | 8篇 |
2023年 | 16篇 |
2022年 | 71篇 |
2021年 | 80篇 |
2020年 | 52篇 |
2019年 | 71篇 |
2018年 | 100篇 |
2017年 | 86篇 |
2016年 | 156篇 |
2015年 | 263篇 |
2014年 | 317篇 |
2013年 | 334篇 |
2012年 | 488篇 |
2011年 | 426篇 |
2010年 | 268篇 |
2009年 | 240篇 |
2008年 | 336篇 |
2007年 | 267篇 |
2006年 | 258篇 |
2005年 | 220篇 |
2004年 | 190篇 |
2003年 | 169篇 |
2002年 | 148篇 |
2001年 | 127篇 |
2000年 | 124篇 |
1999年 | 112篇 |
1998年 | 38篇 |
1997年 | 28篇 |
1996年 | 20篇 |
1995年 | 21篇 |
1994年 | 20篇 |
1993年 | 17篇 |
1992年 | 26篇 |
1991年 | 23篇 |
1990年 | 14篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 9篇 |
1984年 | 4篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1974年 | 7篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1969年 | 4篇 |
1967年 | 5篇 |
1966年 | 5篇 |
排序方式: 共有5232条查询结果,搜索用时 15 毫秒
61.
Ginsenoside Re (Re), a major ginsenoside of ginseng, enhanced the cornified cell envelope (CE) formation in HaCaT keratinocytes under normal conditions. In HaCaT keratinocytes, Re was also able to upregulate filaggrin protein and caspase-14 activity in a concentration-dependent manner. These findings reasonably imply that Re possesses a desirable property of improving skin barrier function. 相似文献
62.
Metabolomics investigation of flavonoid synthesis in soybean leaves depending on the growth stage 总被引:1,自引:0,他引:1
Hyuk-Hwan Song Hyung Won Ryu Kyung Jun Lee Il Yun Jeong Dong Sub Kim Sei-Ryang Oh 《Metabolomics : Official journal of the Metabolomic Society》2014,10(5):833-841
Soybean (Glycine max L.) leaves have unique nutraceutical and pharmacological benefits, and have been widely used as a source of healthy and functional food stuffs in Korea. In this study, we investigated the phytochemical metabolomic changes of soybean leaves depending on growth stages (maturation period) assessed based on UPLC–QTOF–MS analysis. Principal component analysis was carried out to trace the metabolite profiles of the phytochemicals from the vegetable stage (1D) through the seven reproductive stages (R1–R7). On the loading plot, significant changes in the contents of metabolites were found during the growth, and eight flavonoid kaempferol glycosides (2, 3, 6, 8, and 10), daidzein (14), genistein (17), and coumestrol (19) were evaluated as growth markers among the 19 isolated metabolites. The kaempferol glycosides were increasingly synthesized from the 1D to the R6 stage but decreased rapidly at stages R7–R8. The extensively synthesized daidzein and genistein were shown during seed growth in the pod (R5–R6), while coumestrol was increased significantly at stages R7–R8 (maturity period). The synthetic pathway of the flavonoids could be elucidated based on the concentration of the individual metabolites. These results demonstrate that the metabolite production changed depending on the growth stage; a possible pathway could be deduced using metabolomic analysis to provide information regarding physiological characterization and optimal harvesting time for crops. 相似文献
63.
Hyuk-Sung Kwon Eunyong Chung Junse Oh Chang-Ha Lee Ik-Sung Ahn 《Biotechnology and Bioprocess Engineering》2008,13(1):108-114
Manganese peroxidase (MnP) is a key enzyme involved in the lignolysis of white-rot fungi. The purpose of this study is to
investigate the effect of immobilization and culture conditions on MnP production in cultures of Phanerochaete chrysosporium grown on polyurethane foam. Higher concentrations of foam and lower levels of spore inoculums resulted in the formation of
scattered mycelial pellets, increased autolysis of chlamydospore-like cells (a reservoir of MnP), and a higher activity of
MnP. Even though MnP was a secondary metabolite, the addition of 5 times more glucose and diammonium tartrate, as carbon and
nitrogen sources, resulted in a 4 fold increase in the dry cell mass. However, MnP activity decreased under these conditions
to less than half, due to the formation of increasingly dense pellets and the inhibited lysis of chlamydospore-like cells. 相似文献
64.
65.
66.
Joonam Park Kyu Tae Kim Dae Yang Oh Dahee Jin Dohwan Kim Yoon Seok Jung Yong Min Lee 《Liver Transplantation》2020,10(35)
The digital twin technique has been broadly utilized to efficiently and effectively predict the performance and problems associated with real objects via a virtual replica. However, the digitalization of twin electrochemical systems has not been achieved thus far, owing to the large amount of required calculations of numerous and complex differential equations in multiple dimensions. Nevertheless, with the help of continuous progress in hardware and software technologies, the fabrication of a digital twin‐driven electrochemical system and its effective utilization have become a possibility. Herein, a digital twin‐driven all‐solid‐state battery with a solid sulfide electrolyte is built based on a voxel‐based microstructure. Its validity is verified using experimental data, such as effective electronic/ionic conductivities and electrochemical performance, for LiNi0.70Co0.15Mn0.15O2 composite electrodes employing Li6PS5Cl. The fundamental performance of the all‐solid‐state battery is scrutinized by analyzing simulated physical and electrochemical behaviors in terms of mass transport and interfacial electrochemical reaction kinetics. The digital twin model herein reveals valuable but experimentally inaccessible time‐ and space‐resolved information including dead particles, specific contact area, and charge distribution in the 3D domain. Thus, this new computational model is bound to rapidly improve the all‐solid‐state battery technology by saving the research resources and providing valuable insights. 相似文献
67.
68.
Jung Hwan Kim Kyung Won Shim Yeong Sook Yoon Sang Yeoup Lee Sung Soo Kim Sang Woo Oh 《PloS one》2012,7(9)
Background
Cigarette smoking and obesity are leading public health concerns. Both increase the risk for cardiovascular disease, cancer, and metabolic abnormalities. This study was conducted to assess the association between cigarette smoking and different types of obesity.Methodology/Principal Findings
Two hundred eighty-three visitors to university hospitals located in four main provinces of South Korea were participated. All participants were classified as either current/past or never smokers and were divided into quartiles according to the total pack-years. Body mass index, waist circumference, total body fat percentage, and area of visceral and abdominal subcutaneous fat were measured. These results of each groups were compared. Waist circumference, and visceral fat area showed a J- or U-shaped association with total smoking amount during a lifetime. After restricting the analyses to past/current smokers, we found significant dose-dependent associations of smoking pack-years with abdominal and visceral obesity. Overall obesity measured by body mass index and total body fat percentage did not show such associations. Although current smokers clearly showed significant associations, we could not demonstrate these in past smokers, possibly because of the limited sample size.Conclusions/Significance
Although smokers did not show significant difference in mean body mass index than those who never smoked, they showed more metabolically adverse fat distributions with increasing smoking amounts. This finding suggests that smoking is not beneficial for weight control. Therefore, smoking cessation and avoidance of smoking commencement should be addressed as important public health issues in preventing obesity and related complications. 相似文献69.
70.
The vegetative morphology and life history of Halopteris filicina (Grateloup) Kutzing, collected from Korea, were examined in laboratory culture. Field plants attaining 3–5 cm in height were epilithic, tufted, yellowish-brown, and produced numerous erect axes with alternately distichous branches from compact basal discs. They were cultured under a 12:12 h LD photoperiod at 10°-C, 15°C and 20°C to observe the influence of temperature on reproduction. At 10°C plants grew only vegetatively, whereas at 15°C and 20°C they produced unilocular sporangia. Unispores released from sporangia developed into monoecious, anisogamous gametophytes that formed plurilocular female and male gametangia on the same lateral branches. The zygotes, by fusion of female macrogametes and male microgametes, developed into sporophytes bearing unilocular sporangia, whereas the unfused female gametes germinated parthenogenetically. This species was confirmed to have an isomorphic life history, basically similar to the other species of Sphacelariales. 相似文献