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41.
The alcohol dehydrogenase (Adh) region from five planitibia subgroup
species of Hawaiian picture-wing Drosophila has been cloned. A total of 15
kb of DNA in and around the Adh gene has been compared among the five
species. Genetic distances were calculated to determine evolutionary
relationships. These distances agree with previous distances determined by
protein polymorphism and DNA hybridization techniques and can be
interpreted in terms of specific island colonization and speciation
(founder) events over the past 5 Myr. Examination of the restriction maps
of the cloned Adh region from the five species shows many instances of
small deletions, insertion of a transposable element in D. heteroneura, and
the existence of a highly variable region on the 3' side of the Adh gene.
Clustering relationships and rates of DNA change are calculated and
compared with the relationship found for other species of Drosophila.
相似文献
42.
43.
The epidermis of barley leaves is a dynamic intermediary storage compartment of carbohydrates, amino acids and nitrate 总被引:1,自引:0,他引:1
Sugars, amino acids and nitrate were measured in the epidermis of barley seedlings and compared with whole leaf levels. I. Under all conditions, concentrations of glucose and fructose were lower in the epidermis than in the remaining leaf tissues; levels were lowest at the end of the dark period (0.2–1.4 m M ) and increased under conditions of inhibited assimilate export (3–6 m M ). 2. Epidermal sucrose concentrations were very low (« 0.2 m M ) even in excised leaves which had accumulated assimilates. 3. Similar to the sugars, amino acids were also less concentrated in the epidermis than in whole leaf extracts. However, the amino acid profiles showed cell type-specific differences. 4. Nitrate was accumulated in the epidermis. The epidermal pool decreased during nitrate starvation. Since no nitrate reductase activity was associated with the epidermis, nitrate was mobilised from the epidermis and metabolized presumably in the mesophyll. These results suggest that the epidermis functions as a regulated intermediary storage compartment of the leaves and that stored substances are readily available for remobilisation. 相似文献
44.
Hugo G. Hilton Paul J. Norman Neda Nemat-Gorgani Ana Goyos Jill A. Hollenbach Brenna M. Henn Christopher R. Gignoux Lisbeth A. Guethlein Peter Parham 《PLoS genetics》2015,11(8)
Modulating natural killer cell functions in human immunity and reproduction are diverse interactions between the killer cell immunoglobulin-like receptors (KIR) of Natural Killer (NK) cells and HLA class I ligands on the surface of tissue cells. Dominant interactions are between KIR2DL1 and the C2 epitope of HLA-C and between KIR2DL2/3 and the C1 epitope of HLA-C. KhoeSan hunter-gatherers of Southern Africa represent the earliest population divergence known and are the most genetically diverse indigenous people, qualities reflected in their KIR and HLA genes. Of the ten KhoeSan KIR2DL1 alleles, KIR2DL1*022 and KIR2DL1*026 likely originated in the KhoeSan, and later were transmitted at low frequency to the neighboring Zulus through gene flow. These alleles arose by point mutation from other KhoeSan KIR2DL1 alleles that are more widespread globally. Mutation of KIR2DL1*001 gave rise to KIR2DL1*022, causing loss of C2 recognition and gain of C1 recognition. This makes KIR2DL1*022 a more avid and specific C1 receptor than any KIR2DL2/3 allotype. Mutation of KIR2DL1*012 gave rise to KIR2DL1*026, causing premature termination of translation at the end of the transmembrane domain. This makes KIR2DL1*026 a membrane-associated receptor that lacks both a cytoplasmic tail and signaling function. At higher frequencies than their parental allotypes, the combined effect of the KhoeSan-specific KIR2DL1*022 and KIR2DL1*026 is to reduce the frequency of strong inhibitory C2 receptors and increase the frequency of strong inhibitory C1 receptors. Because interaction of KIR2DL1 with C2 is associated with risk of pregnancy disorder, these functional changes are potentially advantageous. Whereas all other KhoeSan KIR2DL1 alleles are present on a wide diversity of centromeric KIR haplotypes, KIR2DL1*026 is present on a single KIR haplotype and KIR2DL1*022 is present on two very similar haplotypes. The high linkage disequilibrium across their haplotypes is consistent with a recent emergence for these KIR2DL1 alleles that have distinctive functions. 相似文献
45.
Jill A. Hollenbach Martha B. Ladner Koy Saeteurn Kent D. Taylor Ling Mei Talin Haritunians Dermot P. B. McGovern Henry A. Erlich Jerome I. Rotter Elizabeth A. Trachtenberg 《Immunogenetics》2009,61(10):663-671
In the present study, we investigated the relationship between the KIR loci and the genes encoding their HLA ligands and genetic
susceptibility to Crohn’s disease (CD). Analyses of the interactions between KIR3DL1, KIR2DL1, KIR2DL2, and KIR2DL3 with their
respective HLA ligands indicate that there is a protective effect for KIR2DL2 in the absence of its HLA ligand C1. Given that
KIR2DL2 and KIR2DL3 segregate as alleles, we compared their genotypic distributions to expectations under Hardy–Weinberg Equilibrium
(HWE) with regard to the HLA ligand C1 status. While all the genotypic distributions conform to expectations under HWE in
controls, in C2 ligand homozygous cases there is significant deviation from HWE, with a reduction of KIR2DL2, KIR2DL3 heterozygotes.
KIR2DL2, KIR2DL3 heterozygosity is the only genotypic combination that confers protection from CD. In addition to the protective
effect (OR = 0.44, CI = 0.22–0.87; p = 0.018) observed in C2 ligand homozygotes, the KIR2DL2, KIR2DL3 genotype is predisposing (OR = 1.34, CI = 1.03–4.53; p = 0.031) in the presence of C1 ligand. A test for trend of HLA class I C ligand group genotypes with KIR2DL2, KIR2DL3 heterozygosity
in cases and controls indicates that C1, C2 ligand group heterozygotes have an intermediate effect on predisposition. These
results show for the first time that disease susceptibility may be related to heterozygosity at a specific KIR locus, and
that HLA ligand genotype influences the relative effect of the KIR genotype. 相似文献
46.
Wagner Vital Gustavo Lazzaro Rezende Leonardo Abreu Jorge Moraes Francisco JA Lemos Itabajara da Silva VazJr Carlos Logullo 《BMC developmental biology》2010,10(1):25
Background
The mosquito A. aegypti is vector of dengue and other viruses. New methods of vector control are needed and can be achieved by a better understanding of the life cycle of this insect. Embryogenesis is a part of A. aegypty life cycle that is poorly understood. In insects in general and in mosquitoes in particular energetic metabolism is well studied during oogenesis, when the oocyte exhibits fast growth, accumulating carbohydrates, lipids and proteins that will meet the regulatory and metabolic needs of the developing embryo. On the other hand, events related with energetic metabolism during A. aegypti embryogenesis are unknown. 相似文献47.
目的 制备一种新型的心肌急性缺血再灌注损伤模型,以探讨一种更符合临床实际需求的实验方法.方法 将20只雌性SD(Sprague-Dawley)大鼠随机分成2组(对照组、实验组),采用结扎主动脉根部引起心肌缺血5min再灌注30 min建立心肌急性缺血再灌注模型;通过应用透射电镜观察心肌细胞超微结构的改变,同时检测心肌组织匀浆丙二醛(Maleic Dialdehyde,MDA)含量、超氧化物歧化酶(Superoxide Dismutase,SOD)活力.结果 透射电镜下超微结构显示实验组较对照组明显加重了心肌组织结构和线粒体的损害;实验组心肌组织MDA明显高于对照组(P<0.01),而SOD明显低于对照组(P<0.01).结论 本实验成功建立了方法简便、易于操作、取材范围广泛的心肌缺血再灌注损伤模型,为心肌缺血再灌注损伤研究提供了一种更为可行的模型. 相似文献
48.
Paul W. Hollenbach Aaron N. Nguyen Helen Brady Michelle Williams Yuhong Ning Normand Richard Leslie Krushel Sharon L. Aukerman Carla Heise Kyle J. MacBeth 《PloS one》2010,5(2)
Background
The cytidine nucleoside analogs azacitidine (AZA) and decitabine (DAC) are used for the treatment of patients with myelodysplastic syndromes and acute myeloid leukemia (AML). Few non-clinical studies have directly compared the mechanisms of action of these agents in a head-to-head fashion, and the agents are often viewed as mechanistically similar DNA hypomethylating agents. To better understand the similarities and differences in mechanisms of these drugs, we compared their in vitro effects on several end points in human AML cell lines.Methodology/Principal Findings
Both drugs effected DNA methyltransferase 1 depletion, DNA hypomethylation, and DNA damage induction, with DAC showing equivalent activity at concentrations 2- to 10-fold lower than AZA. At concentrations above 1 µM, AZA had a greater effect than DAC on reducing cell viability. Both drugs increased the sub-G1 fraction and apoptosis markers, with AZA decreasing all cell cycle phases and DAC causing an increase in G2-M. Total protein synthesis was reduced only by AZA, and drug-modulated gene expression profiles were largely non-overlapping.Conclusions/Significance
These data demonstrate shared mechanisms of action of AZA and DAC on DNA-mediated markers of activity, but distinctly different effects in their actions on cell viability, protein synthesis, cell cycle, and gene expression. The differential effects of AZA may be mediated by RNA incorporation, as the distribution of AZA in nucleic acid of KG-1a cells was 65∶35, RNA∶DNA. 相似文献49.
Huang W Zhang P Zuckett JF Wang L Woolfrey J Song Y Jia ZJ Clizbe LA Su T Tran K Huang B Wong P Sinha U Park G Reed A Malinowski J Hollenbach SJ Scarborough RM Zhu BY 《Bioorganic & medicinal chemistry letters》2003,13(3):561-566
A series of benzoxazinone derivatives was designed and synthesized as factor Xa inhibitors. We demonstrated that the naphthyl moiety in the aniline-based compounds 1 and 2 can be replaced with benzene-fused heterobicycles and biaryls to give factor Xa inhibitors with improved trypsin selectivity. The P4 modifications lead to monoamidines which are moderately active. The benzoxazinones 41-45 are potent against factor Xa, retain the improved trypsin selectivity of the corresponding aniline-based compounds, and show strong antithrombotic effect dose responsively. 相似文献
50.