全文获取类型
收费全文 | 263篇 |
免费 | 5篇 |
国内免费 | 9篇 |
专业分类
教育 | 173篇 |
科学研究 | 41篇 |
各国文化 | 9篇 |
体育 | 13篇 |
综合类 | 8篇 |
文化理论 | 3篇 |
信息传播 | 30篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 7篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 8篇 |
2014年 | 23篇 |
2013年 | 46篇 |
2012年 | 24篇 |
2011年 | 15篇 |
2010年 | 15篇 |
2009年 | 8篇 |
2008年 | 12篇 |
2007年 | 14篇 |
2006年 | 21篇 |
2005年 | 23篇 |
2004年 | 6篇 |
2003年 | 10篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1992年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
排序方式: 共有277条查询结果,搜索用时 15 毫秒
91.
The objective of the present study was to compare the toxicity and availability of Fe(II) and Fe(III) to Caco-2 cells. Cellular
damage was studied by measuring cell proliferation and lactate dehydrogenase (LDH) release. The activities of two major antioxidative
enzymes [superoxide dismutase (SOD) and glutathione peroxidase (GPx)] and differentiation marker (alkaline phosphatase) were
determined after the cells were exposed to different levels of iron salts. The cellular iron concentration was investigated
to evaluate iron bioavailability. The results show that iron uptake of the cells treated with Fe(II) is significantly higher
than that of the cells treated with Fe(III) (P<0.05). Fe(II) at a concentration >1.5 mmol/L was found to be more effective in reducing cellular viability than Fe(III).
LDH release investigation suggests that Fe(II) can reduce stability of the cell membrane. The activities of SOD and GPx of
the cells treated with Fe(II) were higher than those of the cells treated with Fe(III), although both of them increased with
raising iron supply levels. The results indicate that both Fe(II) and Fe(III) could reduce the cellular antioxidase gene expression
at high levels.
Project supported by the International Cooperative Project from the Ministry of Science and Technology of China (No. 2006DFA31030),
the Bureau of Science and Technology of Zhejiang Province (No. 2006C32019) and HarvestPlus-China (No. 8022), and the Program
for Changjiang Scholars and Innovative Research Team in University of China (No. IRT0536) 相似文献
92.
随着第二代在线故障诊断(OBD II)标准在不同品牌汽车上的强制应用,针对普通用户如何很好地了解汽车运行状态和故障诊断的需求,系统开发采用ELM327芯片通过OBDⅡ读取汽车ECU的数据,在PC、PDA或Mobile上显示汽车运行状态和进行故障诊断,省去繁杂的通讯协议,为广大普通用户提供一种简单易用的通用汽车故障诊断系统。 相似文献
93.
对战败以后被停止行使国家主权的日本来说,尽快实现媾和结束占领,恢复行使国家主权,重返国际社会是战后初期最重要的外交课题。在这一过程中,如何以最小的代价,以对己最有利的方式实现媾和成为日本各界关注的焦点。然而,一般来说何时媾和,把何种问题纳入媾和议题等均由掌握媾和主导权的战胜国来决定。二战后美苏矛盾不断激化,东西冷战的乌云迅速蔓延东亚的形势下,掌握对日占领主导权的美国,为使日本尽快成为"东亚防共防波堤",高唱对日"宽大的媾和",致使日本置喙媾和问题的机会陡然增加。在东西冷战迅速蔓延的形势下,安全保障问题和与之相联系的日本周边岛屿的处置问题,成了日本能否谋求同盟国尽早实现媾和的关键。最终日本吉田茂政府接受美军继续驻扎日本本土;牺牲冲绳人民的利益,同意美国以联合国的名义托管琉球(冲绳),日本只保留"潜在主权(或‘残存主权’)"的有限恢复主权的方式实现了同西方阵营的"多数媾和"——即事实上的"片面媾和"。 相似文献
94.
Irony,Silence, and Time: Frederick Douglass on the Fifth of July 总被引:1,自引:0,他引:1
Robert E. Terrill 《Quarterly Journal of Speech》2013,99(3):216-234
Frederick Douglass's oration, "What to the Slave is the Fourth of July?" is a rhetorical masterwork of irony. It illustrates a strategy for enlisting the liberatory potential inherent in the detached and multiple perspective of irony without allowing that detachment to culminate in political impotence. The speech accomplishes this through opening before its audience the expansive visual and temporal spaces in which irony thrives, then collapsing those spaces so irony cannot be sustained. The speech therefore exemplifies a kairotic management of irony's scopic attitude, emphasizing for its audience the importance of seeing when irony is appropriate and when it is not. 相似文献
95.
Denise M. Bostdorff 《Quarterly Journal of Speech》2013,99(4):293-319
The appeal of Bush's post-September 11 discourse lies in its similarities with the Puritan rhetoric of covenant renewal by which ministers brought second- and third-generation Puritans into the church. Through this epideictic discourse, Bush implored younger Americans to uphold the national covenant of their “elders,” the World War II generation, through support of the war on terrorism, and he revitalized the faith of the older generation. Bush's covenant renewal rhetoric in the context of September 11 inaugurated him into the presidency. It also explains his predilection for unilateral and/or pre-emptive action and his call for acts of local community service. 相似文献
96.
Alfredo Salerno Giampietro Lago Andrea Berti Francesco Calì Mario Mirisola Patrizia Carta Carmen Ferro Valentino Romano 《Journal of Cultural Heritage》2005,6(4):313-319
The sarcophagus containing the remains of Federico II, located in the Cathedral of Palermo (Sicily, Italy), was opened on 1998 to perform a multidisciplinary survey [1]. Next to the remains of Federico II and in close contact with them were laying two other skeletons belonging, according to historical records, to Pietro II di Aragona and to an anonymous person (“The Third Individual”), probably a woman. The bones appeared severely deteriorated. Chemical analysis performed on bone samples excluded that the bodies underwent some kind of embalming process. The analysis of mtDNA from bone samples taken from the three skeletons was successful in only one of the two labs involved. The HVR1-mtDNA sequence (region: from nt 16,035 to nt 16,395), obtained from the bone samples of Federico II and “The Third Individual” appear identical but bear double peaks at the same nucleotide positions, suggesting mixing (i.e. contamination) of different mtDNA types. The HVR1 sequence obtained from the bone sample of Pietro II di Aragona does not present double peaks and differ from the Cambridge Reference Sequence (CRS) at six nucleotide positions. Cloning experiment of the Federico II amplicon demonstrated that the mixed mtDNA types are only two: one identical to CRS, the other identical to the sequence of Pietro II di Aragona. A reconstruction of these data are proposed in the Discussion. Due to the problematic context in which this study was carried out (mixed and deteriorated biological material, failure to replicate results in two different labs), our results and reconstruction can only be offered on a tentative basis. It is hoped that the data presented in this study will reveal useful, for future comparison, if further molecular genetics research will be carried out on the royal dynasties that ruled Sicily in the early centuries of the past millennium. 相似文献
97.
In introductory statistics courses, the concept of power is usually presented in the context of testing hypotheses about the population mean. We instead propose an exercise that uses a binomial probability table to introduce the idea of power in the context of testing a population proportion. 相似文献
98.
99.
赖碧淡 《大学图书情报学刊》2005,23(6):36-38
文章从非书资料的编目现状入手,结合ILASⅡ系统的编目功能,分析影响非书资料编目的主要原因及解决办法,并对完善非书资料编目规则及条例提出建议. 相似文献
100.
T. Angeline G. Thiruvarutselvi W. Isabel Rita Mary Aruna Rama Devi Nirmala Jeyaraj 《Indian journal of clinical biochemistry : IJCB》2009,24(2):137-141
The prevalent Ala222Val single nucleotide polymorphism of the MTHFR gene has been shown to be associated with type II diabetes.
The objective of the present study was to find out whether there is genetic predisposition for development of acute myocardial
infarction in type II diabetes mellitus among South Indian Tamil population. PCR-based restriction enzyme analysis was performed
in DNA isolated from 120 acute myocardial infarction patients with diabetes mellitus and 100 non diabetic healthy individuals
with no documented cardiovascular diseases. The results indicate that the MTHFR 677TT genotype is absent in both case and
controls. The MTHFR 677CT genotype was observed among 32 (26.7 %) cases and 20 (20%) controls and the MTHFR 677CC genotype
among 88 (73.3%) cases and 80 (80%) controls. The allelic frequencies were in accordance to Hardy Weinberg equilibrium. There
was no statistical difference in genotype distribution between cases and controls. In conclusion, we suggest that the analysis
of MTHFR genotyping for C677T polymorphism alone need not be considered to find out whether there is genetic predisposition
for development of acute myocardial infarction in type II diabetes mellitus among South Indian Tamil population. 相似文献