全文获取类型
收费全文 | 255篇 |
免费 | 31篇 |
出版年
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 9篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 9篇 |
2014年 | 9篇 |
2013年 | 18篇 |
2012年 | 21篇 |
2011年 | 26篇 |
2010年 | 6篇 |
2009年 | 8篇 |
2008年 | 10篇 |
2007年 | 16篇 |
2006年 | 9篇 |
2005年 | 6篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 8篇 |
2001年 | 8篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 11篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1972年 | 4篇 |
1970年 | 2篇 |
1923年 | 1篇 |
1921年 | 2篇 |
1914年 | 2篇 |
1909年 | 1篇 |
1905年 | 1篇 |
1904年 | 2篇 |
1901年 | 1篇 |
1890年 | 1篇 |
1887年 | 1篇 |
排序方式: 共有286条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Studies on polyphenol content, activities and isozymes of polyphenol oxidase and peroxidase during air-curing in three tobacco types 总被引:3,自引:3,他引:0
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The change in polyphenol content in the primed leaves of burley, flue-cured, and Turkish tobaccos during air-curing was related to the activities and isozymes of polyphenol oxidase and peroxidase. The quantity of chlorogenic acid was rapidly reduced during the first week of curing. The decrease in rutin content during curing was less significant, especially when the concentration of chlorogenic acid was high in leaf tissues. This result was further confirmed by in vitro assays with partially purified tobacco polyphenol oxidase. 相似文献
5.
Detecting non-neutral heterogeneity across a region of DNA sequence in the ratio of polymorphism to divergence 总被引:11,自引:4,他引:7
Natural selection, in the form of balancing selection or selective sweeps,
can result in a decoupling of the amounts of molecular polymorphism and
divergence. Thus natural selection can cause some areas of DNA sequence to
have greater silent polymorphism, relative to divergence between species,
than other areas. It would be useful to have a statistical test for
heterogeneity in the polymorphism to divergence ratio across a region of
DNA sequence, one that could identify heterogeneity greater than that
expected from the neutral processes of mutation, drift, and recombination.
The only currently available test requires that a region be arbitrarily
divided into sections that are compared with each other, and the
subjectivity of this division could be problematic. Here a test is proposed
in which runs of polymorphic and fixed sites are counted, where a "run" is
a set of one or more sites of one type preceded and followed by the other
type. The number of runs is smaller than otherwise expected if
polymorphisms are clumped together. By simulating neutral evolution and
comparing the observed number of runs to the simulations, a statistical
test is possible which does not require any a priori decisions about
subdivision.
相似文献
6.
Feedback control of gene expression 总被引:24,自引:0,他引:24
Jen Sheen 《Photosynthesis research》1994,39(3):427-438
7.
J H Sheen 《Plastic and reconstructive surgery》1978,62(1):24-31
Proceeding from the premise that a "youthful" eyelid has a pretarsal bulge while a "senile" eyelid has a pretarsal flatness, the tarsal fixation technique for lower blepharoplasty has been introduced--to reposition part of the orbicularis in front of the tarsus to produce a pretarsal bulge. The technique is presented as a suggested adjunct to the usual types of lower blepharoplasty. 相似文献
8.
J K Ritter I S Owens M Negishi K Nagata Y Y Sheen J R Gillette H A Sasame 《Biochemistry》1991,30(48):11430-11437
We have isolated a cDNA clone, Nah-2, encoding the cytochrome P-450Nah (naphthalene hydroxylase) from a mouse lung lambda ZAP cDNA library using anti-cytochrome P-450Nah IgG as a probe. This same antibody selectively blocked [Nagata, K., Martin, B.M., Gillette, J.R., & Sasame, H.A. (1990) Drug Metab. Dispos. 18, 557-564] the cytochrome P-450 in mouse lung microsomes that catalyzed the conversion of naphthalene to (1R,2S)-naphthalene 1,2-oxide, which has been postulated as a causative agent in the naphthalene-induced tissue-specific necrosis of Clara cells in mouse lung. The toxic effect is seen in mouse and not in rat. The cDNA encodes a polypeptide of 491 amino acids with a molecular mass of 50 kDa. Northern blot analysis with an Nah-2-specific probe revealed that the mRNA is expressed in a species- and tissue-specific manner, present only in mouse lung and liver and not in that of rat. The mRNA encoding Nah-2 is constitutively expressed and is not induced by either phenobarbital, pyrazole, pregnenolone 16 alpha-carbonitrile, or 3-methylcholanthrene. Comparative amino acid sequence analyses with other documented members of the P-450 gene superfamily revealed that this encoded protein is in the IIF subfamily. To analyze its substrate specificity, the cDNA was inserted into the vector, pAAH5, and expressed in the Saccharomyces cerevisiae strain, AH22. The presence of cytochrome P-450Nah in the microsomes isolated from transformed cells and analyzed by Western blot was confirmed by immunocomplexing product with anti-cytochrome P450Nah IgG. Furthermore, activity toward naphthalene in the microsomes from the transformed cells established that this clone encodes a naphthalene hydroxylase.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
9.
10.