全文获取类型
收费全文 | 2748篇 |
免费 | 172篇 |
国内免费 | 2篇 |
出版年
2022年 | 20篇 |
2021年 | 61篇 |
2020年 | 28篇 |
2019年 | 31篇 |
2018年 | 41篇 |
2017年 | 33篇 |
2016年 | 64篇 |
2015年 | 99篇 |
2014年 | 126篇 |
2013年 | 184篇 |
2012年 | 186篇 |
2011年 | 178篇 |
2010年 | 125篇 |
2009年 | 130篇 |
2008年 | 125篇 |
2007年 | 144篇 |
2006年 | 124篇 |
2005年 | 122篇 |
2004年 | 120篇 |
2003年 | 107篇 |
2002年 | 88篇 |
2001年 | 52篇 |
2000年 | 60篇 |
1999年 | 40篇 |
1998年 | 25篇 |
1997年 | 24篇 |
1996年 | 18篇 |
1995年 | 22篇 |
1994年 | 22篇 |
1993年 | 28篇 |
1992年 | 27篇 |
1991年 | 40篇 |
1990年 | 18篇 |
1989年 | 22篇 |
1988年 | 21篇 |
1987年 | 27篇 |
1986年 | 16篇 |
1985年 | 25篇 |
1984年 | 18篇 |
1983年 | 16篇 |
1980年 | 20篇 |
1979年 | 19篇 |
1977年 | 13篇 |
1976年 | 16篇 |
1975年 | 19篇 |
1973年 | 25篇 |
1972年 | 13篇 |
1971年 | 17篇 |
1967年 | 13篇 |
1966年 | 14篇 |
排序方式: 共有2922条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Nitrous oxide (N2O) decreased in vivo oxidation of histidine in rats fed a basal diet marginally deficient in methionine, although hepatic levels of S-adenosylmethionine (AdoMet) were not significantly altered. Excess dietary methionine increased hepatic levels of AdoMet and increased histidine oxidation. However, it did not protect histidine oxidation when the rats were treated with N2O. Parenteral administration of methionine greatly increased hepatic levels of AdoMet and increased histidine oxidation in normal and N2O treated rats. This indicates that when hepatic levels of AdoMet are greatly elevated by administration of methionine, N2O does not affect in vivo histidine oxidation. 相似文献
5.
Summary Maximum lipase production byAspergillus foetidus was obtained from cultures grown in the medium of 2% olive oil and 0.5% sucrose. The optimal conditions for the production of lipases in the Multigen fermenters were found to be at 500rpm with an airflow of 1.5 liter per mimute. Immobilization of the fungal source was found to be infeasible in natural polymers. 相似文献
6.
It is shown for the first time that the content of ubiquinone of liver increases (2.5 fold) on dietary administration of the
widely-used industrial Plasticizer diethylhexyl Phthalate to the rat. The increase is localized almost entirely in mitochondria
in which the concentration of the quinone Per mg Protein is 1.7 times the control. IncorPoration of the radioactive Precursor
(acetate) reveals that the biosynthesis of ubiquinone is increased in the livers of Plasticizer-administered animals. The
rate of degradation is not altered. 相似文献
7.
Lectins, the divalent or polyvalent (glyco) proteins of non-immune origin of the cells agglutinate cells or other materials,
that display more than one saccharide of sufficient complementarity. Lectins considered ‘identical’ in terms of mono-and disaccharide
specificity can be differentiated by their ability to recognise the fine differences in more complex structures. The present
review discusses the interaction of lectins with various oligosaccharides and their resultant separations due to structural
variations. 相似文献
8.
Hypocotyl segments, 5 to 8 mm length from 4 to 7 day old seedlings, callused on B5 medium supplemented with Kn (0.5 ppm) and NAA (0.1 ppm). Even without transfer, shoots were formed in such cultures. About 20% of the cultures produced multiple shoots. In medium with 1 ppm each of Kn and NAA direct shoots were formed at one end of the hypocotyl segment and callusing was initiated at the other end. The plants obtained in either medium formed roots and could be transferred to soil for further growth.Abbreviations BA
benzyladenine
- 2,4-D
2,4-dichlorophenoxy acetic acid
- GA3
gibberellic acid
- Kn
Kinetin
- NAA
naphthalene acetic acid 相似文献
9.
The development of sclerotia of Botrytis cinerea was examined at four stages during their maturation. The surface structure developed a network of profusely branched hyphae through their coalescence to a compact sclerotial body which was maturated by the deposition of melanin pigment. A characteristic feature of the hyphal cells of B. cinerea during the later stages of development was the presence of paramural bodies (plasmalemmasomes and lomasomes). Electrondense bodies with a limiting double-membrane congregated against the transverse septa of hyphal cells as sclerotia matured and may migrate from cell to cell through septal pores. We suggest that these and the lipid bodies found in hyphal cells may have a storage function in the resting sclerotia. 相似文献
10.
Alkaline phosphatase (AP) was purified to over 90% homogeneity from rat osteosarcoma by acetone precipitation followed by chromatography on DEAE-cellulose, Sephacryl S-200, and hydroxyapatite. The purified enzyme had a specific activity of 759 units/mg protein at its optimal pH (10.5), and a Km of 0.8 mM for p-nitrophenylphosphate. The enzyme's apparent subunit molecular mass on sodium dodecyl sulfate-polyacrylamide gel electrophoresis was 82,000 Da. The heat-inactivation profile and homoarginine inhibition were characteristic of the bone-liver-kidney AP isoenzyme. Monoclonal and polyclonal anti-AP antibodies were prepared and characterized. Polyclonal rabbit antiserum quantitatively precipitated the activity from purified AP preparations and tissue extracts but did not inhibit AP catalytic activity. This antiserum was almost 10-fold less active against heat-inactivated enzyme when tested in a competition assay using 125I-AP. Two distinct monoclonal antibodies were each partly effective in immunoprecipitating AP when tested individually; however, together they precipitated over 90% of the AP activity. 相似文献