全文获取类型
收费全文 | 231篇 |
免费 | 18篇 |
出版年
2022年 | 2篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2017年 | 9篇 |
2016年 | 8篇 |
2015年 | 14篇 |
2014年 | 17篇 |
2013年 | 11篇 |
2012年 | 16篇 |
2011年 | 11篇 |
2010年 | 12篇 |
2009年 | 8篇 |
2008年 | 7篇 |
2007年 | 6篇 |
2006年 | 7篇 |
2005年 | 11篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 9篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 8篇 |
1997年 | 4篇 |
1996年 | 8篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1969年 | 1篇 |
1965年 | 1篇 |
1934年 | 1篇 |
排序方式: 共有249条查询结果,搜索用时 15 毫秒
1.
2.
3.
An Ustilago maydis ergosterol biosynthesis mutant (A14) which is partially blocked in sterol 14alpha-demethylase (P45014DM) activity is described. This mutant accumulated the abnormal 14alpha-methyl sterols, eburicol, 14alpha-methylfecosterol, and obtusifoliol, along with significant amounts of ergosterol. Although the A14 mutant grew nearly as well as the wild type, it was impaired in cell extension growth, which indicated a dysfunction in apical cell wall synthesis. The mutant was also found to be hypersensitive to the azole fungicides penconazole and tebuconazole. 相似文献
4.
The chemiluminescent reaction of luminol during lipoxygenase-catalyzed oxygenations was studied with the purpose of developing a specific luminometric assay for cis,cis-1,4-pentadiene fatty acids directly in aqueous solutions. The addition of picomole levels of either linoleic or arachidonic acids to reaction systems containing 0.04 mM luminol and 40 micrograms/ml of purified soybean lipoxygenase-1 gave light emission curves with a single sharp maximum. Under these conditions the peak heights were linearly dependent on the fatty acid concentration and the detection limit for both of the fatty acids was 2 pmol with a signal to noise ratio of 2. For maximum reproducibility of the assays a procedure for the proper quantitation of the enzyme was developed. The fact that the assay proved to be relatively interference-free was ascribed to the high molar enzyme/substrate ratio (above 1). 相似文献
5.
6.
Sanna Loppi Paula Korhonen Maria Bouvy‐Liivrand Simone Caligola Tiia A. Turunen Mikko P. Turunen Ana Hernandez de Sande Natalia Koosowska Flavia Scoyni Anna Rosell Teresa García‐Berrocoso Sighild Lemarchant Hiramani Dhungana Joan Montaner Jari Koistinaho Katja M. Kanninen Minna U. Kaikkonen Rosalba Giugno Merja Heinniemi Tarja Malm 《Aging cell》2021,20(1)
7.
JA Kiernan 《Biotechnic & histochemistry》2013,88(5-6):203-210
Hexazonium pararosaniline is a valuable reagent that has been used in enzyme activity histochemistry for 50 years. It is an aqueous solution containing the tris-diazonium ion derived from pararosaniline, an aminotriarylmethane dye, and it contains an excess of nitrous acid that was not consumed in the diazotization reaction. Other investigators have found that immersion for 2 min in an acidic (pH 3.5) 0.0015 M hexazonium pararosaniline solution can protect cryostat sections of unfixed animal tissues from the deleterious effects of aqueous reagents such as buffered solutions used in immunohistochemistry, while preserving specific affinities for antibodies. In the present investigation hexazonium pararosaniline protected lymphoid tissue and striated muscle against the damaging effects of water or saline. The same protection was conferred on unfixed sections treated with dilute nitrous or hydrochloric acid in concentrations similar to those in hexazonium pararosaniline solutions. Model tissues (solutions, gels or films containing gelatin and/or bovine albumin) responded predictably to well known cross-linking (formaldehyde) or coagulant (mercuric chloride) fixatives. Hexazonium pararosaniline solutions prevented the dissolution of protein gels in water only after 9 or more days of contact, during which time considerable swelling occurred. It is concluded that there is no evidence for a “fixative” action of hexazonium pararosaniline. The protective effect on frozen sections of unfixed tissue is attributable probably to the low pH of the solution. 相似文献
8.
Allison Jones Andrew E. Teschendorff Quanxi Li Jane D. Hayward Athilakshmi Kannan Tim Mould James West Michal Zikan David Cibula Heidi Fiegl Shih-Han Lee Elisabeth Wik Richard Hadwin Rupali Arora Charlotte Lemech Henna Turunen P?ivi Pakarinen Ian J. Jacobs Helga B. Salvesen Milan K. Bagchi Indrani C. Bagchi Martin Widschwendter 《PLoS medicine》2013,10(11)
9.
Hydrobiologia - Forestry-related land use can cause increasing instream sedimentation, burying and eradicating stream bryophytes, with severe ecological consequences. However, there is limited... 相似文献
10.
Water hyacinth Eichhornia crassipes is considered the most damaging aquatic weed in the world. However, few studies have quantified the impact of this weed economically and ecologically, and even fewer studies have quantified the benefits of its control. This paper focuses on water loss saving as the benefit derived from biological control of this plant between 1990 and 2013 at New Year’s Dam, Alicedale, Eastern Cape, South Africa. Estimates of water loss due to evapotranspiration from water hyacinth vary significantly; therefore, the study used three different rates, high, medium and low. A conservative raw agriculture value of R 0.26 per m3 was used to calculate the benefits derived by the water saved. The present benefit and cost values were determined using 10% and 5% discount rates. The benefit/cost ratio at the low evapotranspiration rate was less than one, implying that biological control was not economically viable but, at the higher evapotranspiration rates, the return justified the costs of biological control. However, at the marginal value product of water, the inclusion of the costs of damage to infrastructure, or the adverse effects of water hyacinth on biodiversity, would justify the use of biological control, even at the low transpiration rate. 相似文献