全文获取类型
收费全文 | 660篇 |
免费 | 17篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 10篇 |
2021年 | 20篇 |
2020年 | 22篇 |
2019年 | 11篇 |
2018年 | 14篇 |
2017年 | 10篇 |
2016年 | 11篇 |
2015年 | 26篇 |
2014年 | 15篇 |
2013年 | 27篇 |
2012年 | 34篇 |
2011年 | 43篇 |
2010年 | 47篇 |
2009年 | 67篇 |
2008年 | 57篇 |
2007年 | 48篇 |
2006年 | 52篇 |
2005年 | 44篇 |
2004年 | 19篇 |
2003年 | 16篇 |
2002年 | 30篇 |
2001年 | 11篇 |
2000年 | 17篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 1篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 2篇 |
排序方式: 共有677条查询结果,搜索用时 15 毫秒
111.
112.
今年是中国共产党成立90周年,也是辛亥革命爆发100周年,这两件关系中国命运的大事相隔10年,看似巧合,其实有着必然的联系。这是因为,辛亥革命要通过资本主义道路使中华民族复兴的路没有走通,所以使选择社会主义道路的中国共产党登上了复兴中华民族大业的历史舞台。近一个世纪的历史证明,中国共产党为中华民族复兴提供了根本的政治前提,抓住了难得的发展机遇,创造了良好的内外环境,继承并发扬光大了辛亥革命的未竟事业,使中华民族伟大复兴正在一步步变成现实。 相似文献
113.
中国保存有众多砖质文物建筑,目前这些文物多处于户外环境中,面临严重盐害导致的掏蚀损毁问题。因而,研究兼具脱盐功能的加固材料成为砖质文物等保护的一种创新思路,加固材料的研制和工艺技术的开发是其重点和难点,具有重大的社会需求和急迫性。为此,本工作从可溶性盐的破坏机制出发,研究出一种双组分无机加固材料,加固方法是Ba(OH)_2甲醇溶液与H_2C_2O_4、H_3PO_4乙醇溶液交替滴加,并模拟可溶性盐(NaCl、KCl、Na_2SO_4)分布的典型环境,进行加固、除盐,借助X射线衍射仪(XRD)、X射线荧光光谱仪(XRF)和无线阻尼抗钻仪等现代科学仪器,追踪盐的流出与转化过程。结果表明,本材料不仅能够加固模拟样品,同时能对最具破坏性的盐Na_2SO_4实现不可逆转化,生成重晶石的主要成分BaSO_4,加固与脱盐一次完成,是一种具有实际应用潜力的新材料。 相似文献
114.
115.
116.
Feng Li Li Wu Cheng Zhu Chaogui Zheng Wei Sun Xinhao Wang Shixun Shao Yao Zhou Tingting He Suyuan Li 《Journal of archaeological science》2013
Understanding how to live successfully within our environment is among the most pressing challenges facing contemporary society. This paper probes the problem based on comparative analysis and discusses the relationship between the spatial–temporal distribution of the Neolithic cultural sites and the geographic context in the Hanjiang River Basin in the south of Shaanxi Province, China. Archaeological studies have identified 175 Neolithic cultural sites in the study area, with a sequence of Laoguantai (14C age 8–7 ka BP), Yangshao (14C age 7–5 ka BP) and the late period of the Neolithic Age (14C age 5–4 ka BP). The total number of archaeological sites, the distribution area and the density all showed an early ascending and later descending trend, but the proportion of the number of archaeological sites in the study area to the corresponding value of the entire Shaanxi Province declined sharply. Spatially, these sites were concentrated on the terraces of the Hanjiang River and its main tributaries with an altitude of 400–800 m. Multiple data were integrated to clarify the critical effects of tectonic and geomorphologic conditions on the distribution of the Neolithic sites. Further comparisons revealed the correlation of Holocene climate change and environmental evolution with the Neolithic cultural succession in the study area that ameliorated conditions to generally promote the development of the primitive culture while degeneration coincided with the culture's transition or interruption. The discussion on the origin of the primitive culture and the temporal–spatial distribution corresponding to the regional culture differentiation sheds light on the complex and dynamic human–nature interaction system during the Neolithic Age, thus emphasising the wider field-based investigation and high-resolution reconstruction works of the palaeoclimate and palaeoenvironment in the future. 相似文献
117.
Dong-Xun Yuan Yi-Chun Zhang Yu-Jie Zhang Tong-Xing Zhu Shu-Zhong Shen 《Alcheringa: An Australasian Journal of Paleontology》2013,37(4):546-556
Yuan, D.X., Zhang, Y.C., Zhang, Y.J., Zhu, T.X. & Shen, S.Z., 2014. First records of Wuchiapingian (Late Permian) conodonts in the Xainza area, Lhasa Block, Tibet, and their palaeobiogeographic implications. Alcheringa 38, 546–556. ISSN 0311-5518.Conodonts are among the best fossil groups to provide high-resolution biostratigraphic correlation and resolve the palaeobiogeographic evolution of the Permian. However, they have been rarely reported from the Lhasa Block in Tibet. Here we report the first discovery of Wuchiapingian (early Lopingian) conodonts from the Xiala Formation in the Lhasa Block, Tibet. This conodont fauna includes two genera and three species (Clarkina liangshanensis, C. orientalis, Iranognathus sp.). The conodont fauna indicates that the Xiala Formation previously assigned to the Guadalupian actually ranges from late Kungurian to late Wuchiapingian. The existence of the late Wuchiapingian conodont species Clarkina orientalis and C. liangshanensis in the Lhasa Block provides additional data to support the viewpoint that this block probably had been in a warm-water regime during the Wuchiapingian (Lopingian).Dong-Xun Yuan [yuanzi55@163. com], School of Earth Sciences and Engineering, Nanjing University, 22 Hankou Road, Nanjing, 210093, PR China and State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing, 210008, PR China; Yi-Chun Zhang [yczhang@nigpas. ac. cn] and Shu-Zhong Shen [szshen@nigpas. ac. cn] (corresponding author), State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing, 210008, PR China; Yu-Jie Zhang [zebiac@163. com] and Tong-Xing Zhu [ztongxing88@yahoo. com. cn], Chengdu Center, China Geological Survey, 2 Renming Road North, Chengdu, 610081, PR China. Received 9.1.2014; revised 1.4.2014; accepted 28.4.2014. 相似文献
118.
119.
浙江上林湖出土了一批秘色瓷,与法门寺地宫出土的秘色瓷在外观、造型、装烧方式上相似。通过对窑址的实地调查与样本的科技检测分析(包括热释光测年、化学成分检测、显微结构分析、吸水率测试)发现,这批秘色瓷与一般品质的越窑青瓷在胎釉化学成分与显微结构上具有较高的一致性,因此从化学成分和显微结构角度并不能将秘色瓷从越窑青瓷中区分开来。此外,在工艺技术上,秘色瓷的特点是坯泥处理细致,修坯严格,施釉均匀,并使用瓷质匣钵密封装烧。所以,秘色瓷是越窑青瓷中工艺技术较好的一部分精品瓷。 相似文献
120.