全文获取类型
收费全文 | 413篇 |
免费 | 80篇 |
专业分类
493篇 |
出版年
2022年 | 5篇 |
2021年 | 7篇 |
2019年 | 7篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 7篇 |
2015年 | 15篇 |
2014年 | 16篇 |
2013年 | 12篇 |
2012年 | 24篇 |
2011年 | 18篇 |
2010年 | 20篇 |
2009年 | 19篇 |
2008年 | 16篇 |
2007年 | 19篇 |
2006年 | 13篇 |
2005年 | 15篇 |
2004年 | 12篇 |
2003年 | 12篇 |
2002年 | 6篇 |
2001年 | 9篇 |
2000年 | 9篇 |
1999年 | 11篇 |
1998年 | 16篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 13篇 |
1993年 | 10篇 |
1992年 | 13篇 |
1991年 | 19篇 |
1990年 | 15篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 10篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1971年 | 2篇 |
1969年 | 2篇 |
排序方式: 共有493条查询结果,搜索用时 15 毫秒
1.
Steven J. Tucker David McClelland Kristina Sep?i? Roderick H. Scott 《生物化学与生物物理学报:生物膜》2003,1614(2):171-181
The ability of two alkyl pyridinium sponge toxin preparations (poly-APS and halitoxin) to form transient pores/lesions in cell membranes and allow transfection of plasmid cDNA have been investigated using HEK 293 cells. Poly-APS and halitoxin preparations caused a collapse in membrane potential, reductions in input resistance and increased Ca2+ permeability. At least partial recovery was observed after poly-APS application but recovery was more rarely seen with halitoxin. The transfection with plasmid cDNAs for an enhanced green fluorescent protein (EGFP) and human tumour necrosis factor receptor 2 (TNFR2) was assessed for both toxin preparations and compared with lipofectamine. Stable transfection was achieved with poly-APS although it was less efficient than lipofectamine. These results show that viable cells transfected with alien cDNA can be obtained using novel transient pore-forming alkyl pyridinium sponge toxins and a simple pre-incubation protocol. This provides the first proof of principle that pore-forming alkyl pyridinium compounds can be used to deliver cDNA to the intracellular environment without permanently compromising the plasma membrane. 相似文献
2.
3.
4.
Controlled partial restriction digestions of DNA by competition with modification methyltransferases 总被引:3,自引:0,他引:3
Competitive reactions, using defined ratios of DNA restriction methyltransferase to endonuclease, are shown to result in reliable partial restriction digests of DNA. This method is suitable over a wide range of DNA concentrations and works on DNA in liquid or embedded in agarose. Simultaneous methylase/endonuclease reactions using endonucleases that cleave human DNA very infrequently, such as ClaI or NotI, should generate very large discrete partial DNA fragments suitable for physical mapping in the million base-pair range. Another possible application of methylase/endonuclease competitive reactions is the production of defined partial digests for making cosmid, lambda, or other genomic libraries. 相似文献
5.
D B McClelland 《BMJ (Clinical research ed.)》1990,300(6716):35-37
6.
M. A. L. Smith L. Art Spomer M. J. Meyer M. T. McClelland 《Plant Cell, Tissue and Organ Culture》1989,19(2):91-102
Microcomputerized video image analysis was adapted for rapid, objective, and non-intrusive quantification of shoot growth and development for plants growing in vitro. Custom-developed staging arrangements were essential to insure accurate viewing and representation of the plants in each of three standard culture vessels. Shoot length measurements from digitized culture images were strongly correlated with length measured manually ex vitro. Image analysis weighted density measurements of proliferating microcultures (even with irregular growth habits) provided a reliable indicator of shoot culture fresh weight. Non-destructive time course evaluations of growth rate and quality were demonstrated.Abbreviations FW
fresh weight
- WD
weighted density 相似文献
7.
Bruno W. S. Sobral Rhonda J. Honeycutt Alan G. Atherly Michael McClelland 《Plant Molecular Biology Reporter》1990,8(4):253-275
TheOryza sativa (rice) genome is small (600 to 900 megabase pairs) when compared to that of other monocotyledonous plants. Rice was the first
of the major cereals to be successfully transformed and regenerated. An RFLP map with approximately 300 markers is readily
available, and the DNA content per map unit is only two to three times that ofArabidopsis thaliana. Rice is also the main staple food for the majority of peoples in the world. We developed techniques for the preparation
of intact genomic DNA from Indica and Japonica subspecies of rice, used statistical methods to determine which restriction
endonucleases are rare-cutting, and used pulsed-field gel electrophoresis (PFE) to separate large fragments of rice DNA. Southern
hybridization to blotted rice PFE gels was used to show that the digests were complete. The long-term goal of our work is
to generate an integrated genetic/physical map for the rice genome, as well as helping to establish rice as a model for map-based
gene cloning and genome analysis. 相似文献
8.
9.
Parentage determination in maize hybrids using the arbitrarily primed polymerase chain reaction (AP-PCR) 总被引:9,自引:0,他引:9
J. Welsh R. J. Honeycutt M. McClelland B. W. S. Sobral 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1991,82(4):473-476
Summary Using a novel procedure based on the polymerase chain reaction, we have developed a rapid, efficient, and economical method for identifying plant genotypes. The arbitrarily primed polymerase chain reaction (AP-PCR) generates reproducible fingerprints from any organism, without the need for DNA sequence information. These fingerprints include DNA fragment polymorphisms that can be (1) used for varietal identification and parentage determination, (2) followed in segregating populations produced by crosses, (3) used as markers for the construction of genetic maps, and (4) used to generate dendograms of phylogenetic relationships, especially at the intraspecific level. AP-PCR requires only minute quantities of DNA (10–25 ng per reaction) and therefore can be used in situations in which DNA is limiting. We demonstrate the use of AP-PCR to identify inbred parents of hybrid maize plants in double-blind experiments. 相似文献
10.
When dCTP is replaced by methyl5-dCTP in the polymerase chain reaction some templates cannot be efficiently amplified by Taq polymerase or Vent polymerase using standard cycling parameters. However, this phenomenon can be overcome by increasing the temperature of the denaturation steps to 100 degrees C, or by adding dITP to destabilize the m5dC:dG base pairs. Once the block to amplification of m5dC-substituted DNA was overcome, methylated DNA from the 'superpolylinker' of the plasmid pSL 1180 was used as a substrate to check the methyl-sensitivity of a variety of restriction endonucleases. The m5dC-substituted DNAs should also be valuable substrates for defining the specificity of methyl-dependent endonucleases. 相似文献