全文获取类型
收费全文 | 2277篇 |
免费 | 30篇 |
国内免费 | 4篇 |
专业分类
教育 | 1665篇 |
科学研究 | 263篇 |
各国文化 | 24篇 |
体育 | 107篇 |
综合类 | 1篇 |
文化理论 | 35篇 |
信息传播 | 216篇 |
出版年
2021年 | 21篇 |
2020年 | 29篇 |
2019年 | 52篇 |
2018年 | 69篇 |
2017年 | 55篇 |
2016年 | 54篇 |
2015年 | 36篇 |
2014年 | 47篇 |
2013年 | 609篇 |
2012年 | 45篇 |
2011年 | 42篇 |
2010年 | 32篇 |
2009年 | 27篇 |
2008年 | 48篇 |
2007年 | 36篇 |
2006年 | 33篇 |
2005年 | 33篇 |
2004年 | 37篇 |
2003年 | 32篇 |
2002年 | 39篇 |
2001年 | 22篇 |
2000年 | 27篇 |
1999年 | 25篇 |
1998年 | 21篇 |
1997年 | 21篇 |
1996年 | 24篇 |
1995年 | 18篇 |
1994年 | 17篇 |
1993年 | 26篇 |
1992年 | 23篇 |
1991年 | 20篇 |
1990年 | 20篇 |
1989年 | 28篇 |
1988年 | 16篇 |
1987年 | 28篇 |
1986年 | 19篇 |
1984年 | 17篇 |
1983年 | 18篇 |
1982年 | 21篇 |
1981年 | 25篇 |
1980年 | 25篇 |
1979年 | 21篇 |
1978年 | 21篇 |
1974年 | 17篇 |
1972年 | 17篇 |
1971年 | 16篇 |
1969年 | 14篇 |
1968年 | 17篇 |
1967年 | 17篇 |
1966年 | 14篇 |
排序方式: 共有2311条查询结果,搜索用时 31 毫秒
31.
32.
33.
In this paper a summary is given of the various processes which have been proposed for making the potash in the natural silicates available as a fertilizer.Experimental trials of a new rotary kiln process for treating feldspar are described, which depends upon a previous treatment before furnacing, consisting of a method of aggregating or clumping the mix so that chemical contact of the reacting substances is brought about during the subsequent processing. The qualitative and quantitative results obtained on a number of experimental trials on a mill scale of operation are presented and discussed. It is shown that it is possible to economically manufacture a potash fertilizer containing free lime from feldspar, and for a sufficiently low cost to make an industry based upon the method worthy of consideration. 相似文献
34.
35.
36.
37.
38.
39.
40.
David Alan George Poh-Ling Tan Jeffrey Frank Clewett 《Environmental Education Research》2016,22(1):62-88
Using a participatory learning approach, we report on the delivery and evaluation of a climate change and risk assessment tool to help manage water risks within the agricultural sector. Post-graduate water-professional students from a range of countries, from both developed and emerging economies were involved in using this tool. Our approach included participative learning tools – group discussion, software, and risk matrices. The materials developed met the needs of the students, allowing these students to incorporate their learning and adapt the package of materials for use in their home countries. Analysis of evaluations show that the tools and materials are particularly useful and emphasizes the need for sound learning materials and tools, funding to deliver training, and policy support to accelerate education and adoption of authentic climate change adaptation practices. The expected benefits for water professionals about climate change will be translated into improved socioeconomic and environmental outcomes if adopted. 相似文献