全文获取类型
收费全文 | 612篇 |
免费 | 35篇 |
专业分类
647篇 |
出版年
2023年 | 7篇 |
2022年 | 7篇 |
2021年 | 21篇 |
2020年 | 15篇 |
2019年 | 16篇 |
2018年 | 27篇 |
2017年 | 17篇 |
2016年 | 21篇 |
2015年 | 21篇 |
2014年 | 40篇 |
2013年 | 39篇 |
2012年 | 34篇 |
2011年 | 37篇 |
2010年 | 17篇 |
2009年 | 19篇 |
2008年 | 24篇 |
2007年 | 25篇 |
2006年 | 27篇 |
2005年 | 21篇 |
2004年 | 24篇 |
2003年 | 13篇 |
2002年 | 17篇 |
2001年 | 11篇 |
2000年 | 26篇 |
1999年 | 20篇 |
1998年 | 10篇 |
1997年 | 9篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1992年 | 14篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1966年 | 3篇 |
1962年 | 2篇 |
1961年 | 1篇 |
排序方式: 共有647条查询结果,搜索用时 0 毫秒
641.
The requirement of citric acid is increasing every year. Therefore, it is important to have an efficient recovery method following the production of citric acid. At present, most of the manufacturers use the classical method of citric acid recovery which is a precipitation technique using calcium salt followed by filtration and subsequently treated with sulphuric acid. This review focuses on the new developments of recovery of citric acid from the fermentation broth. 相似文献
642.
B. B. Panda C. B. S. R. Sharma 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1979,55(6):253-255
Summary Ten Organophosphorus (OP) insecticides are tested for their genetic toxicology in the Hordeum vulgare system. Of these, 8 OPs induced chlorophyll mutations of which 6 are new discoveries. 相似文献
643.
644.
Rotating simplex method of optimization has been successfully used to determine the optimal conditions for extracellular pectinase production by Aspergillus niger in batch bioreactor. Maximum production of 1.132 U of polymethylgalacturonase, 1.313 U of polygalacturonase and 0.0091 U of pectinlyase was obtained at pH (controlled). 3.38; agitation rate, 483 rpm and aeration rate, 2.12 vvm. These conditions were found to be more suitable for pectinase production. 相似文献
645.
Recent significant contributions to the design of large-scale plant cell cultures for secondary metabolite production include: the development of a strategy to control the concentration of dissolved gases at constant shear; a surface immobilization technique to retain cell mass at high mixing rates; and a modified stirred-tank reactor with a mesh cage to prevent damage of hairy root cultures. 相似文献
646.
Using spectrophotometric and spectrofluorometric techniques, the interaction of iodine and 2-anthracene sulfonate (ANS) with the phospholipids (PL) isolated from four genetically correlated Salmonella minnesota isolates viz., a smooth form (S), a deeply rough mutant (Rc) and two intermediate forms (Ra and Rb) were studied. Appearance of an isosbestic point and a new band in absorption spectra indicated charge-transfer (C-T) interaction of iodine with the PL through the formation of 1:1 complex. Stern-Volmer type fluorescence quenching of PL was observed with the addition of iodine to PL, while PL enhanced the fluorescence of anionic dye ANS. The values of the binding constants between iodine/PL and ANS/PL, measured by using suitable equations, showed a systematic gradation in the molecular properties of the PL in the membrane structure in smooth (S) and rough (Ra, Rb and Rc) mutants of Salmonella minnesota. 相似文献
647.
Flooding is one of the most hazardous natural disasters and a major stress constraint to rice production throughout the world, which results in huge economic losses. The frequency and duration of flooding is predicted to increase in near future as a result of global climate change. Breeding of flooding tolerance in rice is a challenging task because of the complexity of the component traits, screening technique, environmental factors and genetic interactions. A great progress has been made during last two decades to find out the flooding tolerance mechanism in rice. An important breakthrough in submergence research was achieved by the identification of major quantitative trait locus (QTL) SUB1 in rice chromosomes that acts as the primary contributor for tolerance. This enabled the use of marker-assisted backcrossing (MABC) to transfer SUB1 QTL into popular varieties which showed yield advantages in flood prone areas. However, SUB1 varieties are not always tolerant to stagnant flooding and flooding during germination stage. So, gene pyramiding approach can be used by combining several important traits to develop new breeding rice lines that confer tolerances to different types of flooding. This review highlights the important germplasm/genetic resources of rice to different types of flooding stress. A brief discussion on the genes and genetic mechanism in rice exhibited to different types of flooding tolerance was discussed for the development of flood tolerant rice variety. Further research on developing multiple stresses tolerant rice can be achieved by combining SUB1 with other tolerance traits/genes for wider adaptation in the rain-fed rice ecosystems. 相似文献