解剖学和形态学
麻醉学
听力与言语-语言病理学
行为科学
心脏和心血管系统
细胞和组织工程学
临床神经病学
危重症监护医学
牙科,口腔外科和医学
皮肤病学
急诊医学
内分泌学和新陈代谢
肠胃学和肝脏学
老人病学和老年医学
卫生保健科学和服务
血液学
免疫学
传染病
综合和补充性医学
医学伦理学
医学信息学
医学实验室技术
医学,全科和内科
医学,法律
医学,研究和试验
神经系统科学
护理
营养学和饮食学
产科医学和妇科医学
肿瘤学
眼科学
整形外科学
耳鼻喉科学
病理学
儿科学
周围血管疾病
药理学和药剂学
生理学
基本医疗保健
精神病学
公共、环境和职业卫生
放射学,核医学和医学成像
康复学
生殖生物学
呼吸系统
风湿病学
运动科学
外科学
毒理学
热带医学
泌尿学和肾脏学
病毒学
老年医学
健康政策和服务
心理学,临床
abstract::The mouse major transplantation antigens H-2K, H-2D and H-2L are highly polymorphic cell-surface glycoproteins which may serve as recognition elements in cell-cell interactions. Each antigen possesses a number of alloantigenic determinants defined by antisera of various specificities. Recently, monoclonal antibodies h...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/300755a0
更新日期:1982-12-23 00:00:00
abstract::The development of cancer is contingent on the emergence of at least one clone of transformed cells. One method used to investigate whether human tumours are monoclonal depends on the mosaicism in the normal tissues of women heterozygous for the two forms of the enzyme glucose-6-phosphate dehydrogenase (G-6-PD). This ...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/299822a0
更新日期:1982-10-28 00:00:00
abstract::A parliamentary and union delegation has expressed to the British government its concern over the possible demise of the Genetic Manipulation Advisory Group (GMAG). The delegation proposed that GMAG continue to ensure the safe development of recombinant DNA technology and extend its role to cover the ethics of human ...
journal_title:Nature
pub_type: 新闻
doi:10.1038/299387a0
更新日期:1982-09-30 00:00:00
abstract::The functional assay of a eukaryotic mRNA, into which additional AUG codons have been introduced by in vitro mutagenesis, shows that a translational initiation site need not necessarily be the nearest AUG codon to the 5' end of a mRNA. Hence, the sequence surrounding the AUG, and not simply its position relative to th...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/299221a0
更新日期:1982-09-16 00:00:00
abstract::Halobacterium halobium is an obligately halophilic archaebacterium of interest to molecular biologists for many reasons, one of which is the unexplained high frequency (10(-4)-10(-2) mutants per cell plated) at which it yields readily identifiable and unstable mutants. We showed previously that the genome of H. halobi...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/299182a0
更新日期:1982-09-09 00:00:00
abstract::Novel capsomeric complexes, pentamers and hexamers were detected as chemical entities in phage Q beta. Both were composed of identical protein subunits and stabilized by intermolecular disulphide bonds. Their numbers per particle were about 12 for pentamers and about 20 for hexamers--consistent with theoretical expect...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/298819a0
更新日期:1982-08-26 00:00:00
abstract::Since the initial discovery that the DNase I sensitivity of the globin genes in different cell types correlates with globin gene expression, this relationship has been shown to hold true for a variety of genes, including the genes for ovalbumin, conalbumun, alpha- and beta-globin in chicken, several heat-shock protein...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/298578a0
更新日期:1982-08-05 00:00:00
abstract::Hypogonadism in the mutant hpg mouse is characterized by a deficiency of hypothalamic gonadotropin releasing hormone (GnRH). Affected male mice exhibit immature reproductive organs, small abdominal testes and low pituitary and plasma gonadotropin concentrations. Recent studies have demonstrated the potential of fetal ...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/298468a0
更新日期:1982-07-29 00:00:00
abstract::The structure of the operator-binding domain of the lambda repressor has been determined at 3.2 A resolution. This domain contains an extended N-terminal arm and five alpha-helices. Model-building studies of the repressor-operator complex suggest that alpha-helices, especially the N-terminal parts of these helices, ma...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/298443a0
更新日期:1982-07-29 00:00:00
abstract::A wide range of receptors are located at the blood sinusoidal aspect of the hepatocyte plasma membrane. Many circulating ligands that bind to receptors on the cell surfaces are interiorized along two pathways. Asialoglycoproteins are transferred from the plasma membrane to lysosomes and degraded, whereas immunoglobuli...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/298398a0
更新日期:1982-07-22 00:00:00
abstract::The biosynthesis of many of the complement proteins by cells of the monocyte-macrophage series has been established. Studies on these cells using radiolabelled amino acids demonstrated synthesis of precursor proteins (pro-complement), and the native complement protein similar in size to that found in the plasma. Howev...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/298389a0
更新日期:1982-07-22 00:00:00
abstract::Curare has long been regarded as a typical competitive antagonist of acetylcholine (ACh) at the vertebrate neuromuscular junction. Recently, however, it has been shown that curare can also block the channels opened by ACh at the frog neuromuscular junction as well as on rat and Aplysia neurones; moreover, curare is ab...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/298272a0
更新日期:1982-07-15 00:00:00
abstract::A review of fossil mammalian faunas from the Middle Awash indicates they span most of the later Neogene and document evolutionary change in several mammalian groups, especially Primates, Proboscidea and Artiodactyla. Oldowan artefacts first appear in the late Pliocene, while Acheulian and later industries and apparent...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/298025a0
更新日期:1982-07-01 00:00:00
abstract::Photoreceptors of the vertebrate retina hyperpolarize in response to light. The hyperpolarization elicited by a brief flash is approximately ten times slower in rods than in cones of the same retina. We have examined the amplification and temporal properties of synaptic transfer of rod and cone signals to a common pos...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/296862a0
更新日期:1982-04-29 00:00:00
abstract::The first open meeting to discuss the growing issue of commercialism in academic research was convened by the New York Bar Association's patent committee. Participants included Steven Muller, president of Johns Hopkins University, Joshua Lederberg, president of Rockefeller University, and A. Thomas Bartlett, presiden...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/296792a0
更新日期:1982-04-29 00:00:00
abstract::A soluble enzyme system has been discovered which specifically recognizes and replicates plasmids containing the Escherichia coli chromosomal origin, oriC. Electron microscopy has shown that plasmid replication begins at or near oriC from which it progresses bidirectionally to completion. Control of initiation of a cy...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/296623a0
更新日期:1982-04-15 00:00:00
abstract::A report adopted by the Council of Europe lists eight recommendations on the legal, ethical, and social issues raised by recombinant DNA research. The legislators stressed that the right to a "genetic inheritance free from any form of engineering" should be included in the European Human Rights Convention, and that s...
journal_title:Nature
pub_type: 新闻
doi:10.1038/295545a0
更新日期:1982-02-18 00:00:00
abstract::A high degree of polymorphism for the length and copy number of rDNA spacers, in both the X and Y chromosome clusters, has been found in a wild population of Drosophila melanogaster. The genetic behaviour of rDNA structural variants in separate and mixed populations derived from isofemale lines suggest that they are n...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/295564a0
更新日期:1982-02-18 00:00:00
abstract::Proviruses of avian leukosis virus (ALV) are located in the vicinity of a putative cellular oncogene (c-myc) in ALV-induced bursal lymphomas. Enhanced expression of c-myc occurs in association with proviruses found in any of three configurations: (I) on the 5' side ('upstream') of c-myc in the same transcriptional ori...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/295209a0
更新日期:1982-01-21 00:00:00
abstract::Molecular cloning and DNA sequencing have yielded considerable structural information about proenkephalin. All previously characterized intermediate peptides of the enkephalin pathways in bovine adrenal medulla have now been aligned into an unambiguous primary structure. Two basic amino acid residues serve as processi...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/295206a0
更新日期:1982-01-21 00:00:00
abstract::The split promoter sequences of a tRNALeuCUG gene of Xenopus laevis have been mapped to nucleotides 13-20 and 51-64 of the tRNALeu coding sequences. The sequences closely coincide with two conserved sequence blocks present in all eukaryotic tRNA genes. The two conserved sequence blocks were found to be exchangeable be...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/294626a0
更新日期:1981-12-17 00:00:00
abstract::Kalka is one of about 14 major layered mafic-ultramafic intrusions forming the Giles Complex in central Australia1. The stratigraphical section of the Kalka Intrusion passes from a basal pyroxenite zone (450 + m) through norite and olivine gabbro zones (3,500 m) to an uppermost anorthosite zone (800 + m)2. Further res...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/294155a0
更新日期:1981-11-12 00:00:00
abstract::The single endogenous DBA/2J ectropic provirus segregated concordantly with the dilute (d) coat colour mutation on chromosome 9 in 53/53 DBA/2J-derived recombinant inbred mouse strains and all seven inbred and mutant strains tested that carry the d allele. Analysis of DNA from a spontaneous DBA/2J d revertant (d+2J) s...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/293370a0
更新日期:1981-10-01 00:00:00
abstract::The effect of ions on the light-sensitive current of retinal rods was studied by sucking the inner segment into a tightly fitting capillary with the outer segment projecting into a flowing solution. This new method showed that the light-sensitive pathway, in which Na+ is the normal carrier of current, has an ionic sel...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/292502a0
更新日期:1981-08-06 00:00:00
abstract::The mitotic recombination behaviour of a duplication of the his4 region on chromosome III in the yeast Saccharomyces cerevisiae was studied. The major recombination event between the duplicated segments is gene conversion unassociated with reciprocal recombination. The rad52-1 mutation preferentially decreases mitotic...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/292306a0
更新日期:1981-07-23 00:00:00
abstract::Metallothioneins are small cysteine-rich proteins that bind heavy metals such as zinc, cadmium, copper and mercury. Recent interest in these proteins has focused on the part they play in zinc metabolism and heavy metal detoxification. Our interest in metallothionein genes stems largely from the observations that these...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/292267a0
更新日期:1981-07-16 00:00:00
abstract::The primary structure of the poliovirus genome has been determined. The RNA molecule is 7,433 nucleotides long, polyadenylated at the 3' terminus, and covalently linked to a small protein (VPg) at the 5' terminus. An open reading frame of 2,207 consecutive triplets spans over 89% of the nucleotide sequence and codes f...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/291547a0
更新日期:1981-06-18 00:00:00
abstract::The amino-terminal region of the common corticotropin/beta-lipotrophin (beta-LPH) precursor has been identified in the AtT-20 mouse tumor cells as a glycopeptide with an apparent molecular weight of 16,000 (the '16K fragment'). A third melanotropin core sequence or gamma-MSH similar to that found in ACTH and beta-LPH ...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/291156a0
更新日期:1981-05-14 00:00:00
abstract::The widely occurring tetradecapeptide somatostatin (SRIF-14) has been variously implicated as a neurotransmitter, a neurohormone, a cybernin (local regulatory factor) and a hormone. In the first isolation of SRIF-14 from hypothalamic extracts and subsequent extracts of other tissues, peptides of higher molecular weigh...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/291076a0
更新日期:1981-05-07 00:00:00
abstract::An amino acid sequence analysis of the N-terminal immunoglobulin heavy and light chain variable regions (VH and VL) from 16 hybridoma proteins which bind phosphorylcholine as well as the complete sequence analysis of 9 of these VH regions is presented. There seem to be more VH regions participating in the phosphorylch...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/291029a0
更新日期:1981-05-07 00:00:00
abstract::The discovery of intervening sequences (introns) in DNA led Gilbert and Tonegawa to suggest that a new protein could have been produced by bringing together certain segments of pre-existing ones. However, Blake argued that if DNA was so organized that coding sequences (exons) correspond to structural as well as functi...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/291090a0
更新日期:1981-05-07 00:00:00
abstract::The three-dimensional structure of the 66-amino acid cro repressor protein of bacteriophage lambda suggests how it binds to its operator DNA. We propose that a dimer of cro protein is bound to the B-form of DNA with the 2-fold axis of the dimer coincident with the 2-fold axis of DNA. A pair of 2-fold-related alpha-hel...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/290754a0
更新日期:1981-04-30 00:00:00
abstract::Several species related to Drosophila melanogaster have two loci containing sequences which code for the major heat-shock protein of molecular weight 70,000 (hsp70). These sequences are arranged as two pairs of inverted repeats. The structure of the 87C locus in D. melanogaster seems to have arisen through DNA inserti...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/290677a0
更新日期:1981-04-23 00:00:00
abstract::The histocompatibility-Y (H-Y) antigen is a minor histocompatibility antigen which has been detected on cell surfaces from the heterogametic sexes of mammalian, bird, amphibian, teleost and invertebrate species. H-Y is thought to be a male-determining substance in mammals because of its almost perfect correlation with...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/290503a0
更新日期:1981-04-09 00:00:00
abstract::In associative learning, the activated neurones undergo a variety of concomitant functional alterations--increases or decreases of firing activity and modifications of membrane potential or resistance and of synaptic responsiveness. Synaptic transmission which can be strengthened only when there is paired activity in ...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/290413a0
更新日期:1981-04-02 00:00:00
abstract::The enzyme complex nitrogenase, which reduces N2 to NH+4, involves two redox proteins, both irreversibly damaged by O2 (ref. 1). Enzyme activity therefore requires anaerobic conditions, a source of reductant and a large amount of ATP (approximately 16 ATPs per N2). In both aerobic and facultative anaerobic N2-fixing b...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/290424a0
更新日期:1981-04-02 00:00:00
abstract::(Na+ + K+)ATPase contains two different subunits, a catalytic subunit (alpha) and a subunit with uncertain function (beta). The enzyme binds ATP, ouabain and vanadate, and can be phosphorylated by ATP as well as by inorganic phosphate. From the previously reported maximal binding and phosphorylation capacities of 3.5-...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/290338a0
更新日期:1981-03-26 00:00:00
abstract::The rapid development of the silk glands of Bombyx mori during the last larval instar shows two phases. During the first 4 days, in both the middle and posterior parts of the silk glands, the ribosomal machinery is assembled and the synthesis of housekeeping proteins starts. During the second phase (the last 4 days), ...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/290267a0
更新日期:1981-03-19 00:00:00
abstract::The Ca2+ + Mg2+-activated ATPase of the sarcoplasmic reticulum is responsible for the active Ca2+ transport of this membrane system, the key feature of which is the formation of an energy-rich phosphorylated transport enzyme (EP) and its conversion. To understand the Ca2+-transport mechanism, it is essential to clarif...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/290271a0
更新日期:1981-03-19 00:00:00
abstract::The identical structure of two racially distinct alpha 1-globin alleles and the high degree of homology between the alpha 1- and alpha 2-globin loci indicate that mechanisms exist for suppression of allelic polymorphisms and for exchange of genetic information within the alpha-globin gene complex. ...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/290026a0
更新日期:1981-03-05 00:00:00