全文获取类型
收费全文 | 243篇 |
免费 | 9篇 |
专业分类
林业 | 32篇 |
农学 | 3篇 |
40篇 | |
综合类 | 67篇 |
农作物 | 12篇 |
水产渔业 | 6篇 |
畜牧兽医 | 69篇 |
园艺 | 2篇 |
植物保护 | 21篇 |
出版年
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2013年 | 9篇 |
2012年 | 14篇 |
2011年 | 15篇 |
2010年 | 10篇 |
2009年 | 12篇 |
2008年 | 12篇 |
2007年 | 4篇 |
2006年 | 13篇 |
2005年 | 10篇 |
2004年 | 6篇 |
2003年 | 8篇 |
2002年 | 11篇 |
2001年 | 2篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 2篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1979年 | 2篇 |
1974年 | 2篇 |
1970年 | 4篇 |
1967年 | 2篇 |
1943年 | 1篇 |
1942年 | 1篇 |
1941年 | 1篇 |
1935年 | 1篇 |
1934年 | 1篇 |
1933年 | 1篇 |
1932年 | 1篇 |
1931年 | 1篇 |
1930年 | 2篇 |
1927年 | 1篇 |
1925年 | 1篇 |
1924年 | 1篇 |
1921年 | 2篇 |
排序方式: 共有252条查询结果,搜索用时 0 毫秒
251.
Much of what needs to be changed in U.S. industry involves close ties to manufacturing, design for manufacturability, a rapid design cycle, and up-to-date technical knowledge on the part of the engineers themselves. Being up-to-date requires conscious company effort. Traveling to meetings, reading the technical literature, and being a part of the engineering community are necessities if we are to compete with others who make these efforts and are thus better able to incorporate technical change rapidly into their own products. Outside the product improvement cycle, a research (as opposed to development) organization in industry must have close ties to development and manufacturing in order to succeed. With these close ties, researchers can understand the progress of the cycle and can introduce new steps at the appropriate time and in an acceptable form. A research organization that surmounts the internal barriers and becomes an accepted contributor to the development and manufacturing process can, because of its greater technical depth, its scientific knowledge, and its close ties with the university world, become a forceful initiator of progress. It is more difficult, in our opinion, to make these contributions from a university base and from government laboratories as they are now constituted. Much has been said by industry and government leaders about reforming the educational system and strengthening the national science base-things that help build a strong foundation. A strong science base supplies a vast storehouse of new ideas, and a good educational system provides engineers and manufacturing workers with knowledge; but strength here cannot make up for inadequacies in the functioning of the development and manufacturing cycle. The United States must learn to succeed, not only in the ladder type of innovation in which a wholly new idea from science creates a wholly new product (the science-dominated process at which we have succeeded in the past), but also in the rapid, cyclical, engineer-dominated process of incremental product improvement. Neither process is a substitute for the other; we need both. 相似文献
252.
Large-scale biotechnological production of the antileukemic marine natural product sorbicillactone A
下载免费PDF全文
![点击此处可从《Marine drugs》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Bringmann G Gulder TA Lang G Schmitt S Stöhr R Wiese J Nagel K Imhoff JF 《Marine drugs》2007,5(2):23-30
In the search for novel bioactive compounds from sponge-derived microorganisms, we have recently identified two structurally and biosynthetically unprecedented fungal metabolites, the novel-type alkaloids sorbicillactone A and sorbicillactone B. Sorbicillactone A is active against leukemia cells without showing notable cytotoxicity. Therefore, we have developed an efficient process for its biotechnological production and isolation on a large scale supplying sufficient material for the ongoing preclinical investigations and structure-activity relationship (SAR) studies. 相似文献