全文获取类型
收费全文 | 386篇 |
免费 | 37篇 |
国内免费 | 9篇 |
出版年
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 20篇 |
2014年 | 16篇 |
2013年 | 21篇 |
2012年 | 21篇 |
2011年 | 22篇 |
2010年 | 12篇 |
2009年 | 13篇 |
2008年 | 11篇 |
2007年 | 13篇 |
2006年 | 21篇 |
2005年 | 13篇 |
2004年 | 18篇 |
2003年 | 6篇 |
2002年 | 9篇 |
2001年 | 15篇 |
2000年 | 12篇 |
1999年 | 8篇 |
1998年 | 10篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1993年 | 4篇 |
1992年 | 12篇 |
1991年 | 9篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1954年 | 2篇 |
1930年 | 3篇 |
排序方式: 共有432条查询结果,搜索用时 13 毫秒
171.
Mathias Ziegler Wolfgang Dubiel Alexander M. Pimenov Yuri V. Tikhonov Ruslan T. Toguzov Wolfgang Henke Gerhard Gerber 《Molecular and cellular biochemistry》1990,93(1):7-12
Summary The degradation of intramitochondrial adenine nucleotides to nucleosides and bases was investigated by incubating isolated rat liver mitochondria at 37°C under non-phosphorylating conditions in the presence of oligomycin and carboxyatractyloside. Within 30 min the adenine nucleotides were degraded by about 25 per cent. The main products formed were adenosine and inosine the contents of which increased five- to sevenfold.Compartmentation studies revealed that about 50 to 60 per cent of the adenosine formed remained inside the organelles whereas inosine was almost completely released into the surrounding medium. Outside the mitochondria only very small amounts of adenine nucleotides were detected. Similar incubations in the presence of [14C]-adenosine yielded no [14C]-inosine ruling out extramitochondrial adenosine deamination.It is concluded that endogenous adenine nucleotides can be degraded in mitochondria via AMP dephosphorylation and subsequent adenosine deamination. A purine nucleoside transport system mediating at least the efflux of inosine from the mitochondria is suggested. 相似文献
172.
John K. Darby Patrick J. Willems Phil Nakashima Jeff Johnsen Robert E. Ferrell Ellen M. Wijsman Daniella S. Gerhard Nicholas C. Dracopoli David Housman Jurgen Henke Michael L. Fowler Thomas B. Shows John S. O''''Brien Luca L. Cavalli-Sforza 《American journal of human genetics》1988,43(5):749-755
Human alpha-L-fucosidase is a lysosomal enzyme responsible for hydrolysis of alpha-L-fucoside linkages in fucoglycoconjugates. A single gene, FUCA 1, located on chromosome 1p34.1-1p36.1 encodes for alpha-L-fucosidase activity. To gain insight into the nature of the molecular defects leading to fucosidosis, we have characterized the genomic structure of FUCA 1. Restriction-endonuclease analysis suggests that at least seven exons dispersed over 22 kb are present in genomic FUCA 1. Two restriction-fragment-length polymorphisms (RFLPs) have been identified in the Caucasian population. The PvuII and BglI RFLPs each have two codominant alleles in Hardy-Weinberg equilibrium. Allele frequencies for the PvuII RFLP are .70/.30, and those for the BglI RFLP .63/.37. Both RFLPs are in strong linkage disequilibrium with each other, with a correlation coefficient of .94. The polymorphism information content (PIC) of the combined DNA markers is .38, high enough to be useful in the prenatal diagnosis of fucosidosis. The combined lod score for linkage between the fucosidosis mutation and FUCA 1 markers in two families was significant at a recombination fraction of 0. This suggests that the fucosidosis mutation resides in FUCA 1. 相似文献
173.
W. Pfleiderer K. P. Stengele F. Bergmann M. Resmini C. Henke 《Nucleosides, nucleotides & nucleic acids》2013,32(3-5):843-846
Abstract New blocking group combinations have been investigated to achieve an automated synthesis of a tRNA and structural analogs on solid-support. The use of the 4-methoxytetrahydropyranyl group for 2′-OH-protection and the dansylethoxycarbonyl group for the 5′-OH position shows in the phosphoramidite approach good results. In the arabino series the 2-(4-nitrophenyl)ethoxycarbonyl group is a perfect 2′-OH blocking group which can be combined with the dimethoxytrityl residue in the usual manner to give high yields and pure materials. 相似文献
174.
N K Clapp A H McArthur R L Carson M A Henke O C Peck J D Wood 《Laboratory animal science》1987,37(2):217-219
Endoscopic visualization and biopsy have been performed under anesthesia in more than 65 tamarins and marmosets to study the pathogenesis of colitis and cancer of the colon. This procedure allows examination of the large bowel from the anus to the cecum and has been repeated at 2-6 month intervals with few complications. However, care must be exercised not to perforate the colon. Successful use of this technique will permit study of the pathogenesis of colonic diseases throughout the life of the animal and should provide cause-effect information about colitis and colon cancer in tamarins that may apply to the human diseases. 相似文献
175.
J Harms A Schneider U Hess I Pragst J Henke R Busch K B?ttcher 《Biomedizinische Technik》2000,45(3):43-50
Allograft rejection and its differentiation from other causes of organ dysfunction remains a diagnostic problem in liver transplant patients. Currently, acute rejection can be prevented only by a combination of diagnostic and therapeutic modalities. The diagnostic potential of a novel implantable telemetric rejection monitoring device has been assessed on the basis of the noninvasive impedance analysis in normal and liver transplanted pigs. The electric impedance data were correlated with biochemical and histological parameters. Acute rejection was correctly predicted in n = 4, and correctly excluded in n = 32, biopsy-related impedance recordings (p = 0.004). A correlation between impedance measurements and severity of histological findings r = 0.84; p = 0.0001) was confirmed. Only the biochemical parameters SGLDH and serum bilirubin revealed a comparable correlation. Impedance gradient analysis revealed evidence of a physiological relationship between liver function and the electrical properties of the organ. Telemetric impedance analysis would appear a promising means of assessing acute rejection noninvasively. 相似文献
176.
Background and Aims
Functional–structural plant models (FSPMs) simulate biological processes at different spatial scales. Methods exist for multiscale data representation and modification, but the advantages of using multiple scales in the dynamic aspects of FSPMs remain unclear. Results from multiscale models in various other areas of science that share fundamental modelling issues with FSPMs suggest that potential advantages do exist, and this study therefore aims to introduce an approach to multiscale modelling in FSPMs.Methods
A three-part graph data structure and grammar is revisited, and presented with a conceptual framework for multiscale modelling. The framework is used for identifying roles, categorizing and describing scale-to-scale interactions, thus allowing alternative approaches to model development as opposed to correlation-based modelling at a single scale. Reverse information flow (from macro- to micro-scale) is catered for in the framework. The methods are implemented within the programming language XL.Key Results
Three example models are implemented using the proposed multiscale graph model and framework. The first illustrates the fundamental usage of the graph data structure and grammar, the second uses probabilistic modelling for organs at the fine scale in order to derive crown growth, and the third combines multiscale plant topology with ozone trends and metabolic network simulations in order to model juvenile beech stands under exposure to a toxic trace gas.Conclusions
The graph data structure supports data representation and grammar operations at multiple scales. The results demonstrate that multiscale modelling is a viable method in FSPM and an alternative to correlation-based modelling. Advantages and disadvantages of multiscale modelling are illustrated by comparisons with single-scale implementations, leading to motivations for further research in sensitivity analysis and run-time efficiency for these models. 相似文献177.
Haberland A Zaitsev S Waldöfner N Erdmann B Böttger M Henke W 《Molecular biology reports》2009,36(5):1083-1093
Efficient non-viral vectors for the in vivo siRNA transfer are still being searched for. Comparing the differences of the
structural appearance of siRNA and pDNA one would assume differences in the assembling behaviour between these polyanions
when using polycationic vectors such as nuclear proteins. The spontaneous assembly of nuclear proteins such as histone H1
(H1) with pDNA as polyanion which has intensively been investigated over the last decade, showed a particulate structure of
the resulting complexes. For an efficient in vivo use small almost monomolecular structures are searched for. Using siRNA
as the polyanion might enforce this structural prerequisite lacking unwanted aggregation processes, exploiting the molecular
size of siRNA. We therefore investigated the structure of H1/siRNA complexes. Five commonly used methods characterizing the
resulting assemblies such as retardation gels, static and dynamic light scattering, reduction of ethidium bromide fluorescence,
analytical ultracentrifugation, and electron microscopy were used. From analytical ultracentrifugation we learned that under
physiological salt conditions the siRNA-H1 binding was not cooperative, even though the gel analysis showed disproportionation
which would be an indication for a cooperative binding mode. H1 formed very small and stable complexes with siRNA at a molar
ratio of 1:1 and 1:2. In order to find out if the observed structural appearance of the H1/siRNA complexes is due to unspecific
charge effects only or to special features of H1, polylysine was included in the study. Low molecular weight polylysine (K16) showed also non-cooperative binding with siRNA. 相似文献
178.
179.
JUAN ANTONIO DÍAZ‐PENDÓN M. CARMEN CAÑIZARES ENRIQUE MORIONES EDUARDO R. BEJARANO HENRYK CZOSNEK JESÚS NAVAS‐CASTILLO 《Molecular Plant Pathology》2010,11(4):441-450
Tomato yellow leaf curl disease (TYLCD) is one of the most devastating viral diseases affecting tomato crops in tropical, subtropical and temperate regions of the world. Here, we focus on the interactions through recombination between the different begomovirus species causing TYLCD, provide an overview of the interactions with the cellular genes involved in viral replication, and highlight recent progress on the relationships between these viruses and their vector, the whitefly Bemisia tabaci. Taxonomy: The tomato yellow leaf curl virus‐like viruses (TYLCVs) are a complex of begomoviruses (family Geminiviridae, genus Begomovirus) including 10 accepted species: Tomato yellow leaf curl Axarquia virus (TYLCAxV), Tomato yellow leaf curl China virus (TYLCCNV), Tomato yellow leaf curl Guangdong virus (TYLCGuV), Tomato yellow leaf curl Indonesia virus (TYLCIDV), Tomato yellow leaf curl Kanchanaburi virus (TYLVKaV), Tomato yellow leaf curl Malaga virus (TYLCMalV), Tomato yellow leaf curl Mali virus (TYLCMLV), Tomato yellow leaf curl Sardinia virus (TYLCSV), Tomato yellow leaf curl Thailand virus (TYLCTHV), Tomato yellow leaf curl Vietnam virus (TYLCVNV) and Tomato yellow leaf curl virus(TYLCV). We follow the species demarcation criteria of the International Committee on Taxonomy of Viruses (ICTV), the most important of which is an 89% nucleotide identity threshold between full‐length DNA‐A component nucleotide sequences for begomovirus species. Strains of a species are defined by a 93% nucleotide identity threshold. Host range: The primary host of TYLCVs is tomato (Solanum lycopersicum), but they can also naturally infect other crops [common bean (Phaseolus vulgaris), sweet pepper (Capsicum annuum), chilli pepper (C. chinense) and tobacco (Nicotiana tabacum)], a number of ornamentals [petunia (Petunia×hybrida) and lisianthus (Eustoma grandiflora)], as well as common weeds (Solanum nigrum and Datura stramonium). TYLCVs also infect the experimental host Nicotiana benthamiana. Disease symptoms: Infected tomato plants are stunted or dwarfed, with leaflets rolled upwards and inwards; young leaves are slightly chlorotic; in recently infected plants, fruits might not be produced or, if produced, are small and unmarketable. In common bean, some TYLCVs produce the bean leaf crumple disease, with thickening, epinasty, crumpling, blade reduction and upward curling of leaves, as well as abnormal shoot proliferation and internode reduction; the very small leaves result in a bushy appearance. 相似文献
180.
Simon Brooker Archie CA Clements Peter J Hotez Simon I Hay Andrew J Tatem Donald AP Bundy Robert W Snow 《Malaria journal》2006,5(1):1-8