全文获取类型
收费全文 | 3291篇 |
免费 | 308篇 |
国内免费 | 2篇 |
出版年
2023年 | 12篇 |
2022年 | 7篇 |
2021年 | 48篇 |
2020年 | 38篇 |
2019年 | 54篇 |
2018年 | 38篇 |
2017年 | 59篇 |
2016年 | 106篇 |
2015年 | 136篇 |
2014年 | 151篇 |
2013年 | 228篇 |
2012年 | 246篇 |
2011年 | 245篇 |
2010年 | 162篇 |
2009年 | 133篇 |
2008年 | 178篇 |
2007年 | 179篇 |
2006年 | 171篇 |
2005年 | 174篇 |
2004年 | 147篇 |
2003年 | 124篇 |
2002年 | 182篇 |
2001年 | 58篇 |
2000年 | 36篇 |
1999年 | 39篇 |
1998年 | 59篇 |
1997年 | 40篇 |
1996年 | 44篇 |
1995年 | 38篇 |
1994年 | 35篇 |
1993年 | 42篇 |
1992年 | 38篇 |
1991年 | 21篇 |
1990年 | 26篇 |
1989年 | 30篇 |
1988年 | 16篇 |
1987年 | 19篇 |
1986年 | 18篇 |
1985年 | 15篇 |
1984年 | 22篇 |
1983年 | 20篇 |
1982年 | 24篇 |
1981年 | 18篇 |
1980年 | 18篇 |
1979年 | 10篇 |
1978年 | 13篇 |
1977年 | 11篇 |
1975年 | 10篇 |
1972年 | 6篇 |
1960年 | 5篇 |
排序方式: 共有3601条查询结果,搜索用时 0 毫秒
1.
2.
Hendrik Verschueren 《Cell biology and toxicology》1985,1(3):145-157
In vitro directional migration of 10 T1/2 fibroblasts is partially inhibited by TPA but not by its non promoting analogues. Other tumor promoters, e.g., phenobarbital, saccharin, and benzoylperoxide had no measurable effect when added in concentrations known to affect in vitro two-step transformation or intercellular communication. Inhibitors of in vitro transformation do not affect migration, except for dexamethasone, which inhibited it. Hence, there is no evidence for a general correlation between tumor promoting potential and inhibition of in vitro directional migration.Abbreviations DDT
1,1,1-trichloro-2,2-bis(p-cholorophenyl) ethane
- DEXA
dexamethasone
- DMSO
dimethylsulfoxide
- RA
retinylacetate
- SD
standard deviation
- SOD
superoxide dismutase
- TPA
12-0-tetradecanoylphorbol-13-acetate; 4-0-Me-TPA, 4-0-methyl-TPA 相似文献
3.
Adnan Cavka Bj?rn Alriksson Shaunita H. Rose Willem H. van Zyl Leif J. J?nsson 《Journal of industrial microbiology & biotechnology》2011,38(8):891-899
The possibility to utilize fiber sludge, waste fibers from pulp mills and lignocellulose-based biorefineries, for combined production of liquid biofuel and biocatalysts was investigated. Without pretreatment, fiber sludge was hydrolyzed enzymatically to monosaccharides, mainly glucose and xylose. In the first of two sequential fermentation steps, the fiber sludge hydrolysate was fermented to cellulosic ethanol with the yeast Saccharomyces cerevisiae. Although the final ethanol yields were similar, the ethanol productivity after 9.5?h was 3.3?g/l/h for the fiber sludge hydrolysate compared with only 2.2?g/l/h for a reference fermentation with similar sugar content. In the second fermentation step, the spent fiber sludge hydrolysate (the stillage obtained after distillation) was used as growth medium for recombinant Aspergillus niger expressing the xylanase-encoding Trichoderma reesei (Hypocrea jecorina) xyn2 gene. The xylanase activity obtained with the spent fiber sludge hydrolysate (8,500?nkat/ml) was higher than that obtained in a standard medium with similar monosaccharide content (1,400?nkat/ml). Analyses based on deglycosylation with N-glycosidase?F suggest that the main part of the recombinant xylanase was unglycosylated and had molecular mass of 20.7?kDa, while a minor part had N-linked glycosylation and molecular mass of 23.6?kDa. Chemical analyses of the growth medium showed that important carbon sources in the spent fiber sludge hydrolysate included xylose, small aliphatic acids, and oligosaccharides. The results show the potential of converting waste fiber sludge to liquid biofuel and enzymes as coproducts in lignocellulose-based biorefineries. 相似文献
4.
5.
Willem O. Kwant 《CMAJ》1980,122(11):1279-1281
6.
7.
8.
9.
Mechanisms of multidrug transporters 总被引:11,自引:0,他引:11
10.
Antony J. Durston Cornelis J. Weijer Johan F. Jongkind Anton Verkerk Ans Timmermans Willem Te Kulve 《Development genes and evolution》1984,194(1):18-24
Summary We report a flow fluorimetric analysis of the DNA content of cells and nuclei from vegetative populations and various developmental stages of the cellular slime mouldDictyostelium discoideum using the dyes Hoechst 33258 and mithramycin. Nuclei from all of these populations showed an identical single DNA-content peak, indicating that most vegetative cells and most cells in all developmental stages are in one phase of the cell cycle. Our own data and findings in the literature indicate that this phase is G2. On the other hand, we also found that various stages, subpopulations of cells at early stages and the different differentiated cell types in the slug stage differ in DNA content per cell. Any particular population typically has one major peak of DNA content, with a modal value that is characteristic for the cell type and for the developmental stage. These differences presumably reflect differences in mitochondrial DNA content per cell. 相似文献