全文获取类型
收费全文 | 3823篇 |
免费 | 206篇 |
国内免费 | 4篇 |
出版年
2023年 | 37篇 |
2022年 | 57篇 |
2021年 | 104篇 |
2020年 | 65篇 |
2019年 | 78篇 |
2018年 | 119篇 |
2017年 | 85篇 |
2016年 | 143篇 |
2015年 | 165篇 |
2014年 | 188篇 |
2013年 | 286篇 |
2012年 | 317篇 |
2011年 | 292篇 |
2010年 | 189篇 |
2009年 | 178篇 |
2008年 | 190篇 |
2007年 | 183篇 |
2006年 | 145篇 |
2005年 | 115篇 |
2004年 | 112篇 |
2003年 | 110篇 |
2002年 | 63篇 |
2001年 | 63篇 |
2000年 | 54篇 |
1999年 | 38篇 |
1998年 | 29篇 |
1997年 | 24篇 |
1996年 | 25篇 |
1995年 | 19篇 |
1994年 | 19篇 |
1993年 | 12篇 |
1992年 | 37篇 |
1991年 | 29篇 |
1990年 | 27篇 |
1989年 | 25篇 |
1988年 | 33篇 |
1987年 | 24篇 |
1986年 | 27篇 |
1985年 | 38篇 |
1984年 | 28篇 |
1983年 | 27篇 |
1982年 | 19篇 |
1981年 | 17篇 |
1979年 | 24篇 |
1978年 | 12篇 |
1977年 | 16篇 |
1974年 | 20篇 |
1972年 | 23篇 |
1971年 | 15篇 |
1969年 | 11篇 |
排序方式: 共有4033条查询结果,搜索用时 31 毫秒
31.
32.
33.
Stem segments of adult plants of Ficus religiosa L. cultured on MS medium containing 1.0 mg/l 2,4-D produced callus. Shoots were regenerated when the induced calli were transferred to medium supplemented with 0.05 to 2.0 mg/l BAP. Callus derived shoots produced roots and developed into plantlets when transferred to medium supplemented with 1.0 mg/l NAA.Abbreviations MS
Murashige and Skoog (1962)
- BAP
6-benzylaminopurine
- NAA
naphthaleneacetic acid
- 2,4-D
2,4-dichlorophenoxyacetic acid 相似文献
34.
Improved synthesis of oligodeoxyribonucleotide using 3-methoxy-4-phenoxybenzoyl group for amino protection. 总被引:1,自引:1,他引:0
下载免费PDF全文
![点击此处可从《Nucleic acids research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
3-Methoxy-4-phenoxybenzoyl group has been used for the protection of exocyclic amino group of nucleosides. In case of 2'-deoxycytidine it has been found to be highly selective under controlled conditions. The N-protected derivatives of 2'-deoxyadenosine and 2'-deoxyguanosine have been found to be sufficiently stable towards acids minimising depurination under conditions of synthesis of oligodeoxyribonucleotide on solid support via phosphotriester approach. The high lipophilicity of the group and milder deprotection conditions are additional advantages. 相似文献
35.
Summary Organic matter has been found to be closely associated with the retention of manganese in an exchangeable form. The destruction of organic matter or its addition decrease or increase the exchangeable form of manganese respectively.The removal of iron and Fe2O3 addition greatly affect the retention of manganese. An increase in Fe2O3 addition increases the retained, reducible and fixed forms (R, r and F values) of manganese in soils. 相似文献
36.
Summary The sieve plate pores of Salix caprea in preparations fixed in glutaraldehyde are normally found to be occupied by slime fibrils showing periodic banding such as occur in a number of other species. Arguments are put forward to suggest that the occurence of fibrils in this position is natural and not an artefact of preparation. The sieve tubes further possess prominent and persistent nucleoli showing a radiating structure of tubules. The endoplasmic reticulum often occurs in parietal stacks reminiscent of other species.This evidence is discussed in relation to the electroosmotic theory of translocation.This work formed part of that submitted for the degree of Ph. D. of the University of London by U. Mishra. 相似文献
37.
Summary The use of paraffin bait technique in the isolation ofNocardia asteroides has been tested in 241 samples of sputa obtained from 235 cases of respiratory diseases.N. asteroides was recovered on 6 occasions from sputum of a patient using the paraffin bait technique. On the other hand cultures of sputa from the same patient on routine agar media such as Sabouraud's agar and Lowenstein Jensen medium yielded only one isolated of the pathogen.This work forms a part of the Ph. D. thesis of P.V.K. submitted to the University of Delhi. 相似文献
38.
39.
40.