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排序方式: 共有329条查询结果,搜索用时 15 毫秒
1.
Globin synthesis on reticulocyte membrane-bound ribosomes 总被引:1,自引:0,他引:1
W R Woodward S D Adamson H M McQueen J W Larson S M Estvanik P Wilairat E Herbert 《The Journal of biological chemistry》1973,248(5):1556-1561
2.
3.
Introduction: A glacial acetic acid wash performed retrospectively or prospectively on visibly bloodstained cervical ThinPrep® specimens can reduce the unsatisfactory rate and increase the number of diagnostic epithelial cells. This study was undertaken to determine which specimens are most likely to benefit from a prospective glacial acetic acid wash. Methods: Bloodstained ThinPrep® specimens selected for routine lysing prior to processing were macroscopically assessed and scored based on the level of blood present (+ to +++). Both unlysed and lysed slides were prepared from each specimen and microscopically examined. Results: Fifty‐eight specimens (32 scored +, 12 ++ and 14+++) were assessed. Three unlysed slides prepared from the ++ specimens and 12 from +++ specimens were evaluated as unsatisfactory due to excessive blood and inadequate numbers of squamous cells. In contrast, only one of the unlysed slides from the 32 + specimens was considered to be unsatisfactory. Almost all the lysed slides were satisfactory and generally more cellular than the unlysed slides. Abnormal cells were found in four cases (both unlysed and lysed paired slides). Discussion: Although the acetic acid wash increases cellularity of bloodstained ThinPrep® specimens, prospectively lysing all bloodstained specimens is an unnecessary procedure. Lysing only very heavily bloodstained specimens prior to processing will reduce laboratory workload, costs and the possibility of specimen mix up. Occasionally a retrospective wash may be required but screening staff should be aware that although blood may be present on an unlysed ThinPrep® slide, a lysed slide should not be requested unless there are insufficient numbers of squamous cells present. 相似文献
4.
The influence of changing temperature on the life history of Daphniopsis ephemeralis 总被引:1,自引:0,他引:1
We present evidence which suggests that for Daphniopsis ephemeralischanges in water temperature may directly cue changes in sexratio, ephippial and parthenogenetic egg production and indirectlydetermine female body size. Field data suggested that over anannual cycle, a population of D. ephemeralis comprised animalswith three distinct life history phases. The first was madeup of exephippial females which hatched in the fall. They produceda second group made up of large parthenogenetic females whichcould produce more than one overwintering generation. In thespring these parthenogenetic females gave rise to a third lifehistory phase which comprised males and small ephippial females.Field enclosure experiments suggested that the small size ofspring females was not related to predation. Laboratory experimentssuggested that ephippial egg production at small body sizeswas associated with increasing temperature. Theseexperiments also suggested that the fall reproductive pattern(parthenogenetic eggs and large body sizes) was associated withdecreasing temperatures. We conclude that directionalityof seasonal temperature change may be the prime factor responsiblefor D. ephemeralis life history changes observed in the field. 相似文献
5.
Hardies SC; Martin SL; Voliva CF; Hutchison CA d; Edgell MH 《Molecular biology and evolution》1986,3(2):109-125
6.
Involvement of the mutated M protein in altered budding polarity of a pantropic mutant, F1-R, of Sendai virus. 总被引:4,自引:2,他引:2 下载免费PDF全文
Wild-type Sendai virus buds at the apical plasma membrane domain of polarized epithelial MDCK cells, whereas a pantropic mutant, F1-R, buds at both the apical and basolateral domains. In F1-R-infected cells, polarized protein transport and the microtubule network are impaired. It has been suggested that the mutated F and/or M proteins in F1-R are responsible for these changes (M. Tashiro, J. T. Seto, H.-D. Klenk, and R. Rott, J. Virol. 67:5902-5910, 1993). To clarify which gene or mutation(s) was responsible for the microtubule disruption which leads to altered budding of F1-R, MDCK cell lines containing the M gene of either the wild type or F1-R were established. When wild-type M protein was expressed at a level corresponding to that synthesized in virus-infected cells, cellular polarity and the integrity of the microtubules were affected to some extent. On the other hand, expression of the mutated F1-R M protein resulted in the formation of giant cells about 40 times larger than normal MDCK cells. Under these conditions, the effects on the microtubule network were enhanced. The microtubules were disrupted and polarized protein transport was impaired as indicated by the nonpolarized secretion of gp80, a host cell glycoprotein normally secreted from the apical domain, and bipolar budding of wild-type and F1-R Sendai viruses. The mutated F glycoprotein of F1-R was transported bipolarly in cells expressing the F1-R M protein, whereas it was transported predominantly to the apical domain when expressed alone or in cells coexpressing the wild-type M protein. These findings indicate that the M protein of F1-R is involved in the disruption of the microtubular network, leading to impairment of cellular polarity, bipolar transport of the F glycoprotein, and bipolar budding of the virus. 相似文献
7.
Predator-induced bottom-up effects in oligotrophic systems 总被引:1,自引:1,他引:0
Five treatments (replication n=2) were applied to mesocosms in an oligotrophic lake (TP=6–10 µg 1-1) to assess the effects of fish on planktonic communities. The treatments were: (1) high fish (30 kg ha–1
Lepomis auritus, Linnaeus), (2) low fish (10 kg ha–1), (3) high removal of zooplankton, (4) low removal of zooplankton and (5) control. Total phosphorus, chlorophyll a, zooplankton biomass, and species richness decreased from high fish > low fish > control > low removal > high removal treatments. The fish treatments were dominated by crustacean zooplankton, while rotifers outnumbered the other zooplankters in the removal treatments. Calculations of zooplankton grazing rates suggested that clearance rates seldom exceeded 2% of the enclosure volume d–1 and were unlikely to have had much influence on phytoplankton biomass. Calculations from a phosphorus bioenergetics model revealed that when fish were present, their excretion rates were higher than the rates ascribed to zooplankton. Diet analysis showed that the fish derived most of their energy from the benthos and periphyton, and that fish excretion and egestion made significant contributions to the very oligotrophic pelagic phosphorus pool. In the absence of fish, zooplankton excretion was highest in the control treatments and lowest in the zooplankton removal treatments. Our results suggest that in oligotrophic systems, planktivorous fish can be significant sources of phosphorus and that fish and zooplankton induced nutrient cycling have significant impacts on planktonic community structure. 相似文献
8.
A major difference between the divergence patterns within the lines-1 families in mice and voles 总被引:3,自引:0,他引:3
Vanlerberghe F; Bonhomme F; Hutchison CA d; Edgell MH 《Molecular biology and evolution》1993,10(4):719-731
L1 retroposons are represented in mice by subfamilies of interspersed
sequences of varied abundance. Previous analyses have indicated that
subfamilies are generated by duplicative transposition of a small number of
members of the L1 family, the progeny of which then become a major
component of the murine L1 population, and are not due to any active
processes generating homology within preexisting groups of elements in a
particular species. In mice, more than a third of the L1 elements belong to
a clade that became active approximately 5 Mya and whose elements are >
or = 95% identical. We have collected sequence information from 13 L1
elements isolated from two species of voles (Rodentia: Microtinae: Microtus
and Arvicola) and have found that divergence within the vole L1 population
is quite different from that in mice, in that there is no abundant
subfamily of homologous elements. Individual L1 elements from voles are
very divergent from one another and belong to a clade that began a period
of elevated duplicative transposition approximately 13 Mya. Sequence
analyses of portions of these divergent L1 elements (approximately 250 bp
each) gave no evidence for concerted evolution having acted on the vole L1
elements since the split of the two vole lineages approximately 3.5 Mya;
that is, the observed interspecific divergence (6.7%-24.7%) is not larger
than the intraspecific divergence (7.9%-27.2%), and phylogenetic analyses
showed no clustering into Arvicola and Microtus clades.
相似文献
9.
Molecular phylogeny and divergence times of drosophilid species 总被引:32,自引:15,他引:17
The phylogenetic relationships and divergence times of 39 drosophilid
species were studied by using the coding region of the Adh gene. Four
genera--Scaptodrosophila, Zaprionus, Drosophila, and Scaptomyza (from
Hawaii)--and three Drosophila subgenera--Drosophila, Engiscaptomyza, and
Sophophora--were included. After conducting statistical analyses of the
nucleotide sequences of the Adh, Adhr (Adh-related gene), and nuclear rRNA
genes and a 905-bp segment of mitochondrial DNA, we used Scaptodrosophila
as the outgroup. The phylogenetic tree obtained showed that the first major
division of drosophilid species occurs between subgenus Sophophora (genus
Drosophila) and the group including subgenera Drosophila and Engiscaptomyza
plus the genera Zaprionus and Scaptomyza. Subgenus Sophophora is then
divided into D. willistoni and the clade of D. obscura and D. melanogaster
species groups. In the other major drosophilid group, Zaprionus first
separates from the other species, and then D. immigrans leaves the
remaining group of species. This remaining group then splits into the D.
repleta group and the Hawaiian drosophilid cluster (Hawaiian Drosophila,
Engiscaptomyza, and Scaptomyza). Engiscaptomyza and Scaptomyza are tightly
clustered. Each of the D. repleta, D. obscura, and D. melanogaster groups
is monophyletic. The splitting of subgenera Drosophila and Sophophora
apparently occurred about 40 Mya, whereas the D. repleta group and the
Hawaiian drosophilid cluster separated about 32 Mya. By contrast, the
splitting of Engiscaptomyza and Scaptomyza occurred only about 11 Mya,
suggesting that Scaptomyza experienced a rapid morphological evolution. The
D. obscura and D. melanogaster groups apparently diverged about 25 Mya.
Many of the D. repleta group species studied here have two functional Adh
genes (Adh-1 and Adh-2), and these duplicated genes can be explained by two
duplication events.
相似文献
10.
A. L. Archibald C. S. Haley J. F. Brown S. Couperwhite H. A. McQueen D. Nicholson W. Coppieters A. Van de Weghe A. Stratil A. K. Winterø M. Fredholm N. J. Larsen V. H. Nielsen D. Milan N. Woloszyn A. Robic M. Dalens J. Riquet J. Gellin J. -C. Caritez G. Burgaud L. Ollivier J. -P. Bidanel M. Vaiman C. Renard H. Geldermann R. Davoli D. Ruyter E. J. M. Verstege M. A. M. Groenen W. Davies B. Høyheim A. Keiserud L. Andersson H. Ellegren M. Johansson L. Marklund J. R. Miller D. V. Anderson Dear E. Signer A. J. Jeffreys C. Moran P. Le Tissier Muladno M. F. Rothschild C. K. Tuggle D. Vaske J. Helm H. -C. Liu A. Rahman T. -P. Yu R. G. Larson C. B. Schmitz 《Mammalian genome》1995,6(3):157-175
A linkage map of the porcine genome has been developed by segregation analysis of 239 genetic markers. Eighty-one of these markers correspond to known genes. Linkage groups have been assigned to all 18 autosomes plus the X Chromosome (Chr). As 69 of the markers on the linkage map have also been mapped physically (by others), there is significant integration of linkage and physical map data. Six informative markers failed to show linkage to these maps. As in other species, the genetic map of the heterogametic sex (male) was significantly shorter (16.5 Morgans) than the genetic map of the homogametic sex (female) (21.5 Morgans). The sex-averaged genetic map of the pig was estimated to be 18 Morgans in length. Mapping information for 61 Type I loci (genes) enhances the contribution of the pig gene map to comparative gene mapping. Because the linkage map incorporates both highly polymorphic Type II loci, predominantly microsatellites, and Type I loci, it will be useful both for large experiments to map quantitative trait loci and for the subsequent isolation of trait genes following a comparative and candidate gene approach. 相似文献