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91.
S Bowman D Lawson D Basham D Brown T Chillingworth C M Churcher A Craig R M Davies K Devlin T Feltwell S Gentles R Gwilliam N Hamlin D Harris S Holroyd T Hornsby P Horrocks K Jagels B Jassal S Kyes J McLean S Moule K Mungall L Murphy K Oliver M A Quail M A Rajandream S Rutter J Skelton R Squares S Squares J E Sulston S Whitehead J R Woodward C Newbold B G Barrell 《Nature》1999,400(6744):532-538
Analysis of Plasmodium falciparum chromosome 3, and comparison with chromosome 2, highlights novel features of chromosome organization and gene structure. The sub-telomeric regions of chromosome 3 show a conserved order of features, including repetitive DNA sequences, members of multigene families involved in pathogenesis and antigenic variation, a number of conserved pseudogenes, and several genes of unknown function. A putative centromere has been identified that has a core region of about 2 kilobases with an extremely high (adenine + thymidine) composition and arrays of tandem repeats. We have predicted 215 protein-coding genes and two transfer RNA genes in the 1,060,106-base-pair chromosome sequence. The predicted protein-coding genes can be divided into three main classes: 52.6% are not spliced, 45.1% have a large exon with short additional 5' or 3' exons, and 2.3% have a multiple exon structure more typical of higher eukaryotes. 相似文献
92.
Type-2 Cu sites are found in all the major branches of life and are often involved in the catalysis of oxygen species. Four
type-2 Cu protein families are selected as model systems for review: amine oxidases, Cu monooxygenases, nitrite reductase/multicopper
oxidase, and CuZn superoxide dismutase. For each model protein, the availability of multiple crystal structures and detailed
enzymological studies provides a detailed molecular view of the type-2 Cu site and delineation of the mechanistic role of
the Cu in biological function. Comparison of these model proteins leads to the identification of common properties of the
Cu sites and insight into the evolution of the trinuclear active site found in multicopper oxidases.
Received 6 July 2007; accepted 18 July 2007 相似文献
93.
R B Murphy 《Experientia》1978,34(2):188-189
Insulin is unaffected by pressures of 48,000 b in the solid state at room temperature, as elucidated both by spectroscopic measurements and bioassay. Its compression curve is reversible. The presence of water does not alter this property. Of a number of other proteins investigated insulin appears to be unique with regard to its pressure stability. The relative rigidity of the molecule combined with its small size may account for some of these properties. 相似文献
94.
Genetically effective and adult population sizes of the Apache silverspot butterfly ( Speyeria nokomiis apacheana ) from the Great Basin of North America were tracked from 1991 to 1997. Speyeria nokomis inhabits mesic habitats in the Great Basin, and its recent declines in abundance have raised concerns about its future persistence. Adult population size estimates determined from mark-recapture methods ranged from 100 to 1900 individuals from 1993 through 1997. Genetically effective population sizes based on temporal changes in allozyme frequencies ranged from less tha 1 individual to 20 individuals between 1991 and 1995. Despite these small annual estimates, it is likely that gene flow resulted in overestimation of genetically effective population sizes. These reusuts, combined with observations in the field, suggest that suitable but vacan habitat patches be maintained for potential recolonization by S. n. apacheana. 相似文献
95.
Radio telemetry was used to study habitat use of breeding male sage grouse ( Centrocercus urophasianus ) at a lek in northeastern Utah during 1983 and 1984. Objectives were to determine if grouse day-use areas differed significantly in sagebrush characteristics from adjacent nonuse areas and to establish a simplified method for use by land managers in identifying grouse use areas. We determined that male grouse used areas of greatest sagebrush height and cover. Our methods provide a means for land managers to identify habitat associated with a lek that is suitable for male sage grouse day use in the event sagebrush alteration is planned within 3 km of a lek. 相似文献
96.
Evidence is presented indicating that Lichanura roseofusca and Lichanura trivirgata are conspecific. Data include the report of an intermediate specimen from El Arco, Baja California Norte, a site midway between the previously known peninsular ranges of the two species; captive hybridization provides additional support for the conclusion. 相似文献
97.
Activation of two signal-transduction systems in hepatocytes by glucagon 总被引:26,自引:0,他引:26
The ability of glucagon to stimulate glycogen breakdown in liver played a key part in the classic identification of cyclic AMP and hormonally stimulated adenylate cyclase. But several observations indicate that glucagon can exert effects independent of elevating intracellular cAMP concentrations. These effects are probably mediated by an elevation of the intracellular concentration of free Ca2+ although the mechanism by which this occurs is unknown. We show here that glucagon, at the low concentrations found physiologically, causes both a breakdown of inositol phospholipids and the production of inositol phosphates. Indeed, we show that the glucagon analogue, (1-N-alpha-trinitrophenylhistidine,12-homoarginine)glucagon (TH-glucagon), which does not activate adenylate cyclase or cause any increase in cAMP in hepatocytes yet can fully stimulate glycogenolysis, gluconeogenesis and urea synthesis, stimulates the production of inositol phosphates. This stimulation of inositol phospholipid metabolism by low concentrations of glucagon provides a mechanism whereby glucagon can exert cAMP-independent actions on target cells. We suggest that hepatocytes possess two distinct receptors for glucagon, a GR-1 receptor coupled to stimulate inositol phospholipid breakdown and a GR-2 receptor coupled to stimulate adenylate cyclase activity. 相似文献
98.
99.
Jing Wang XiaoYun Wu ZiMing Chen ZhaoPing Yue Wei Ma ShanYuan Chen Heng Xiao Robert W. Murphy YaPing Zhang RuiGuang Zan Jing Luo 《科学通报(英文版)》2013,58(31):3738-3746
The phylogenetic relationships of European and African Barbus and their West Asian relatives in Cyprininae remain largely unresolved. Consequently, little is known about the drivers of their evolution, including the possible association of uplifting of the Qinghai-Tibetan Plateau (QTP) with the early divergence of the subfamily. We use complete sequence data of the mitochondrial DNA gene encoding the protein cytochrome b (Cytb) to hypothesize the phylogeny of 85 species belonging to 47 genera in the Cyprininae plus 6 species from the Leuciscinae. We employ 6 other species from Cypriniformes as outgroup taxa and estimate divergence times. Our results indicate that European Barbus sensu stricto lineage including Aulopyge shares a common ancestor with specialized and highly specialized schizothoracins and the genera Cyprinion and Scaphiodonichtys. The common ancestor appears to have originated in the Qinghai-Tibetan Plateau (QTP) region about 19.4–17.8 Ma. Barbus sensu stricto lineage appears to have originated about 16.6–15.5 Ma. Small to medium sized African Barbus sensu lato appear to have had an Oriental origin about 19.1–15.3 Ma and are closely related to Asian Puntius. West Asian Carasobarbus lineage including large African Barbus sensu lato might have originated about 9.94 Ma, also in Oriental Realm and has a close relationship to Asian Neolissochilus and Tor. The large-sized Barbus sensu lato appear to have diverged from Carasobarbus about 7.7 Ma. Finally, the Cyprininae appear to have radiated rapidly into nine lineages and many sublineages from about 27.8 to 17.8 Ma, close to the time of the second-stage tectonic movements of the QTP. Our analyses provide evidence that the uplifting of the QTP drove early diversification of the Cyprininae. Our extensive sampling of species involving all of the important areas results in clear evolutionary scenario for the Cyprininae. 相似文献
100.
Gregori G Ravasio A Murphy CD Schaar K Baird A Bell AR Benuzzi-Mounaix A Bingham R Constantin C Drake RP Edwards M Everson ET Gregory CD Kuramitsu Y Lau W Mithen J Niemann C Park HS Remington BA Reville B Robinson AP Ryutov DD Sakawa Y Yang S Woolsey NC Koenig M Miniati F 《Nature》2012,481(7382):480-483
The standard model for the origin of galactic magnetic fields is through the amplification of seed fields via dynamo or turbulent processes to the level consistent with present observations. Although other mechanisms may also operate, currents from misaligned pressure and temperature gradients (the Biermann battery process) inevitably accompany the formation of galaxies in the absence of a primordial field. Driven by geometrical asymmetries in shocks associated with the collapse of protogalactic structures, the Biermann battery is believed to generate tiny seed fields to a level of about 10(-21)?gauss (refs 7, 8). With the advent of high-power laser systems in the past two decades, a new area of research has opened in which, using simple scaling relations, astrophysical environments can effectively be reproduced in the laboratory. Here we report the results of an experiment that produced seed magnetic fields by the Biermann battery effect. We show that these results can be scaled to the intergalactic medium, where turbulence, acting on timescales of around 700 million years, can amplify the seed fields sufficiently to affect galaxy evolution. 相似文献