全文获取类型
收费全文 | 1566篇 |
免费 | 140篇 |
国内免费 | 1篇 |
专业分类
1707篇 |
出版年
2023年 | 6篇 |
2022年 | 21篇 |
2021年 | 29篇 |
2020年 | 13篇 |
2019年 | 18篇 |
2018年 | 26篇 |
2017年 | 40篇 |
2016年 | 54篇 |
2015年 | 63篇 |
2014年 | 74篇 |
2013年 | 109篇 |
2012年 | 110篇 |
2011年 | 124篇 |
2010年 | 70篇 |
2009年 | 76篇 |
2008年 | 94篇 |
2007年 | 101篇 |
2006年 | 79篇 |
2005年 | 84篇 |
2004年 | 75篇 |
2003年 | 79篇 |
2002年 | 60篇 |
2001年 | 25篇 |
2000年 | 9篇 |
1999年 | 14篇 |
1998年 | 28篇 |
1997年 | 16篇 |
1996年 | 14篇 |
1995年 | 11篇 |
1994年 | 12篇 |
1993年 | 15篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 10篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 14篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1980年 | 8篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1972年 | 3篇 |
1971年 | 5篇 |
排序方式: 共有1707条查询结果,搜索用时 15 毫秒
1.
Charles Romeo Naoko Moriwaki Kerry T. Yasunobu Irwin C. Gunsalus Hideo Koga 《Journal of Protein Chemistry》1987,6(3):253-261
The first 12 NH2-terminal amino acids of the Pseudomonas putida putidaredoxin reductase were shown to be Met-Asn-Ala-Asn-Asp-Asn-Val-Val-Ile-Val-Gly-Thr. Comparison of these data with the DNA sequence of the BamHI-HindIII 197-base fragment derived from the PstI 2.2-kb fragment obtained from the P. putida plasmid showed that the putidaredoxin reductase gene was downstream from the cytochrome P-450 gene and the intergenic region had the 24-nucleotide sequence TAAACACATGGGAGTGCGTGCTAA. The Shine-Dalgarno sequence GGAG was detected in this region. The initiating triplet for the reductase gene was GTG, which normally codes for valine, but in the initiating codon position codes for methionine. From the amino acid sequence and X-ray data comparisons with other flavoproteins, what appears to be the AMP binding region of the FAD can be recognized in the NH2-terminal portion of the reductase involving residues 5–35.This article was presented during the proceedings of the International Conference on Macromolecular Structure and Function, held at the National Defence Medical College, Tokorozawa, Japan, December 1985. 相似文献
2.
3.
Background
Micro-biological research relies on the use of model organisms that act as representatives of their species or subspecies, these are frequently well-characterized laboratory strains. However, it has often become apparent that the model strain initially chosen does not represent important features of the species. For micro-organisms, the diversity of their genomes is such that even the best possible choice of initial strain for sequencing may not assure that the genome obtained adequately represents the species. To acquire information about a species' genome as efficiently as possible, we require a method to choose strains for analysis on the basis of how well they represent the species. 相似文献4.
The glutamate receptor-channel of locust muscle membrane was studied using the patch-clamp technique. Muscles were pretreated with concanavalin A to block receptor-channel desensitization, thus facilitating analysis of receptor-channel gating kinetics. Single channel kinetics were analyzed to aid in identification of the molecular basis of channel gating. Channel dwell-time distributions and dwell-time autocorrelation functions were calculated from single channel data recorded in the precence of 10-4M glutamate. Analysis of the dwell time distributions in terms of mixtures of exponential functions revealed there to be at least three open states of the receptor-channel and at least four closed states. Autocorrelation function analysis showed there to be at least three pathways linking the open states with the closed. This results in a minimal scheme for gating of the glutamate receptor-channel, which is suggestive of allosteric models of receptor-channel gating. 相似文献
5.
Kerry Barringer 《Brittonia》1987,39(3):353-357
Agalinis bandeirensis is a Brazilian species distinguished by linear bracts, short pedicels, and villous stamens.Agalinis ramulifera, from southern Brazil, is distinguished by many, short, leafy branches and small flowers.Agalinis linarioides subsp.rojasi, from Paraguay, is distinguished by paniculate inflorescences, short calyx lobes, and broad corollas.Gerardia bangii, G. digitalis, andG. meyeniana are recognized as species ofAgalinis and appropriate transfers are made. 相似文献
6.
Kerry Barringer 《Brittonia》1986,38(2):128-132
Aristolochia fosteri is a new species with unusual branched trichomes collected in Pasco near Oxapampa.Aristolochia hutchisonii is a prostrate species found in Amazonas and Cajamarca that is related toA. weberbaueri.Aristolochia barbouri is a narrow-leaved, herbaceous liana from Madre de Dios. 相似文献
7.
Kerry Barringer 《Brittonia》1985,37(3):286-290
Elleanthus stolonifer andE. tillandsioides are new species in theE. poiformis complex of sectionChloidelyna.Elleanthus lentii is a new species in sectionStachydelyna. Elleanthus stolonifer is widespread in the mountains of Costa Rica and Panama;E. tillandsioides is found only in the lowland forests of southeastern Costa Rica;E. lentii is limited to the Cordillera de Guanacaste of Costa Rica. 相似文献
8.
Kerry Barringer 《Brittonia》1985,37(2):195-198
Barringer, Kerry (Department of Botany, Field Museum of Natural History, Chicago, IL 60605). Two new species of Esterhazya (Scrophulariaceae) from Brazil. Brittonia 37: 195–198. 1985.—Esterhazya petiolata is a distinctive species with ovate, petiolate leaves, spreading brances, and broadly tubular-campanulate flowers. It is known from the Serra Dourada of Goiás. Esterhazya eitenorum has narrow, lanceolate leaves, acute calyx lobes, and purple-pink flowers and is known from the planalto of Mt. Itatiaia. 相似文献
9.
N-Acetyl-Aspartyl-Glutamate: Regional Levels in Rat Brain and the Effects of Brain Lesions as Determined by a New HPLC Method 总被引:18,自引:11,他引:7
Abstract: An isocratic HPLC method to measure endogenous N -acetyl-aspartyl-glutamate (NAAG) and N -acetyl-aspartate (NAA) is described. After removal of primary amines by passage of tissue extracts over AG-50 resin, the eluate was subject to HPLC anion-exchange analysis and eluted with phosphate buffer with absorbance monitored at 214 nm. The retention time for NAA was 5.6 min and for NAAG 11.4 min with a limit sensitivity of 0.1 nmol. The levels of NAA and NAAG were measured in 16 regions of rat brain and in heart and liver. NAAG was undetectable in heart and liver and exhibited 10-fold variation in concentration among brain regions; the highest levels were found in spinal cord. In contrast, low concentrations of NAA were detectable in heart and liver, and the regional distribution of NAA in brain varied only twofold. The regional distribution of NAA and NAAG correlated poorly. To assess the neuronal localization of these two compounds, the effects of selective brain lesions on their levels were examined. Decortication caused a 28% decrease in NAAG levels in the ipsi-lateral striatum while NAA decreased 38%. Kainate lesion of the striatum resulted in a 31% decrease in NAAG in the ipsilateral striatum, whereas NAA fell by 58%. Kainate lesion of the hippocampus resulted in significant decrements in NAAG and NAA in the hippocampus and septum. Transection of the spinal cord at midthorax resulted in a 51% decrease in NAAG levels immediately caudal and a 40% decrease immediately rostral to the lesion; however, NAA decreased only 30% in these areas. These results are consistent with a neuronal localization of NAAG in brain. Combined with the fact that NAAG interacts with a subpopulation of glutamate receptors, these results suggest that NAAG may serve as an excitatory neurotransmitter. 相似文献
10.
Charles Romeo Naoko Moriwaki Kerry T. Yasunobu Irwin C. Gunsalus Hideo Koga 《The protein journal》1987,6(3):253-261
The first 12 NH2-terminal amino acids of the Pseudomonas putida putidaredoxin reductase were shown to be Met-Asn-Ala-Asn-Asp-Asn-Val-Val-Ile-Val-Gly-Thr. Comparison of these data with the DNA sequence of the BamHI-HindIII 197-base fragment derived from the PstI 2.2-kb fragment obtained from the P. putida plasmid showed that the putidaredoxin reductase gene was downstream from the cytochrome P-450 gene and the intergenic region had the 24-nucleotide sequence TAAACACATGGGAGTGCGTGCTAA. The Shine-Dalgarno sequence GGAG was detected in this region. The initiating triplet for the reductase gene was GTG, which normally codes for valine, but in the initiating codon position codes for methionine. From the amino acid sequence and X-ray data comparisons with other flavoproteins, what appears to be the AMP binding region of the FAD can be recognized in the NH2-terminal portion of the reductase involving residues 5–35. 相似文献