全文获取类型
收费全文 | 246篇 |
免费 | 15篇 |
专业分类
各国政治 | 30篇 |
工人农民 | 3篇 |
世界政治 | 21篇 |
外交国际关系 | 10篇 |
法律 | 145篇 |
中国共产党 | 1篇 |
中国政治 | 2篇 |
政治理论 | 42篇 |
综合类 | 7篇 |
出版年
2024年 | 2篇 |
2022年 | 2篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 2篇 |
2014年 | 11篇 |
2013年 | 27篇 |
2012年 | 10篇 |
2011年 | 9篇 |
2010年 | 7篇 |
2009年 | 5篇 |
2008年 | 10篇 |
2007年 | 8篇 |
2006年 | 5篇 |
2005年 | 8篇 |
2004年 | 14篇 |
2003年 | 11篇 |
2002年 | 10篇 |
2001年 | 7篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 8篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有261条查询结果,搜索用时 15 毫秒
71.
This paper examines the competing claims on land use resulting from the expansion of biofuel production. Sugarcane for biofuel drives agrarian change in So Paulo state, which has become the major ethanol-producing region in Brazil. We analyse how the expansion of sugarcane-based ethanol in So Paulo state has impacted dairy and beef production. Historical changes in land use, production technologies, and product and land prices are described, as well as how these are linked to changing policies in Brazil. We argue that sugarcane/biofuel expansion should be understood in the context of the dynamics of other agricultural sectors and the long-term national political economy rather than as solely due to recent global demand for biofuel. This argument is based on a meticulous analysis of changes in three important sectors - sugarcane, dairy farming, and beef production - and the mutual interactions between these sectors. 相似文献
72.
73.
A simple method for purification of anti-A and anti-B antibodies using glutaraldehyde-fixed human erythrocytes is described. Specific antibodies were first absorbed with the corresponding cells, then eluted by heating at 53 degrees-55 degrees C for 15 min. The method is simple and highly efficient with a fair recovery of 15.6%-34.4%. 相似文献
74.
75.
76.
77.
78.
This paper presents a suicide case of copper sulfate ingestion. Post-mortem autopsy revealed mucous membrane necrosis of the esophagus and the stomach. Histological examination revealed centrilobular necrosis in the liver and renal insufficiency. The quantitative determination of copper, zinc and cadmium in various tissues showed that the copper concentrations in blood, liver, kidney and lung were 3.5-24-fold higher than those of the normal level, whereas zinc and cadmium concentrations were within normal range. Chromatographical patterns on Sephadex G-75 showed that most of the accumulated copper in the liver and kidney was bound to metallothionein (MT), a low molecular weight protein with high metal binding capacity which plays a role in the detoxification of heavy metals, while no copper bound to MT was found in the lung. These results suggest that the formation of Cu-induced MT in the liver and kidney occurred at the early stage in fatal acute copper poisoning. 相似文献
79.
An enzyme-linked immunosorbent assay (ELISA) of the sandwich type for identification of human urinary stains using commercially available anti-human uromucoid was developed. When experimentally prepared urinary stains of humans and animals, 2 by 2 cm in area, were subjected to analysis, human stains could be differentiated from animal ones except chimpanzee and Old World monkey ones. Stains of other human body fluids showed negative reactions. The reactions did not decrease when human urinary stains were stored at room temperature for three months. The present ELISA provides a useful presumptive test for urinary stains of human origin. 相似文献
80.