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101.
Generation of DNA-free Escherichia coli cells by 2-aminopurine requires mismatch repair and nonmethylated DNA 下载免费PDF全文
Undirected mismatch repair initiated by the incorporation of the base analog 2-aminopurine kills DNA-methylation-deficient Escherichia coli dam cells by DNA double-strand breakage. Subsequently, the chromosomal DNA is totally degraded, resulting in DNA-free cells. 相似文献
102.
Minagawa A Takaku H Shibata HS Ishii R Takagi M Yokoyama S Nashimoto M 《Biochemical and biophysical research communications》2006,345(1):385-393
There exists a significant difference in pre-tRNA preference among prokaryotic tRNase Zs. This is an enigma, because pre-tRNAs should form the common L-shaped structure and tRNase Zs should form the common structure based on the alphabeta/betaalpha-fold. To address this issue, we examined six different eubacterial and archaeal tRNase Zs including two newly isolated tRNase Zs for cleavage of 18 different pre-tRNA substrates. Two Thermotoga maritima, one Thermus thermophilus, one Bacillus subtilis, one Thermoplasma acidophilum, and one Pyrobaculum aerophilum enzymes were tested. To our surprise, the newly isolated proteins T. maritima and T. thermophilus showed the weak tRNase Z activity, even though their primary amino acid sequences are, on the whole, quite different from those of the typical tRNase Zs. We confirmed that substrate recognition ability is quite different among those tRNase Zs. In addition, we found that the optimal conditions as a whole differ significantly among the enzymes. From these results, we provided several clues to solve the enigma by showing the potential importance of the 74th-76th nucleotide sequence of pre-tRNA, the flexible arm length of tRNase Z, the divalent metal ion species, and the histidine corresponding His222 in T. maritima tRNase Z. 相似文献
103.
Arakaki N Nishihama T Kohda A Owaki H Kuramoto Y Abe R Kita T Suenaga M Himeda T Kuwajima M Shibata H Higuti T 《Biochimica et biophysica acta》2006,1760(9):1364-1372
We found that a mouse homolog of human DNA polymerase delta interacting protein 38, referred to as Mitogenin I in this paper, and mitochondrial single-stranded DNA-binding protein (mtSSB), identified as upregulated genes in the heart of mice with juvenile visceral steatosis, play a role in the regulation of mitochondrial morphology. We demonstrated that overexpression of Mitogenin I or mtSSB increased elongated or fragmented mitochondria in mouse C2C12 myoblast cells, respectively. On the other hand, the silencing of Mitogenin I or mtSSB by RNA interference led to an increase in fragmented or elongated mitochondria in the cells, respectively, suggesting that Mitogenin I and mtSSB are involved in the processes of mitochondrial fusion and fission, respectively. In addition, we showed that the silencing of Mitogenin I resulted in an increase in the number of trypan blue-positive cells and the silencing of mtSSB resulted in an enhancement of the sensitivity of the cells to apoptotic stimulation by etoposide. The present results demonstrated that these proteins play a role in cell survival. 相似文献
104.
Cytochemical localization of adenylate cyclase activity in the theca folliculi of the mouse graafian follicle 总被引:1,自引:0,他引:1
Summary The adenylate cyclase activity in the theca folliculi of the mouse Graafian follicle was investigated using the electron microscopic cytochemistry. Deposits of reaction product are recognized on the plasma membrane of the fibroblast, theca cell and transitional cell from the fibroblast-like cell to the theca cell (partially or incompletely differentiated theca cell) after incubation with adenylyl-imidodiphosphate (AMP-PNP) as an effective substrate for adenylate cyclase. This fact indicates that these cells have the receptor on the plasma membrane, and the adenylate cyclase-cyclic AMP system is important for the steroid secretion or the collagen fiber production. It is difficult to clarify by this method the relationship between the adenylate cyclase activity and the functional differentiation of the theca cell.Supported by a grant from the Japanese Educational ministry 相似文献
105.
Schönenberger J von Balthazar M Takahashi M Xiao X Crane PR Herendeen PS 《Annals of botany》2012,109(5):921-936
Background and Aims
Ericales are a major group of extant asterid angiosperms that are well represented in the Late Cretaceous fossil record, mainly by flowers, fruits and seeds. Exceptionally well preserved fossil flowers, here described as Glandulocalyx upatoiensis gen. & sp. nov., from the Santonian of Georgia, USA, yield new detailed evidence of floral structure in one of these early members of Ericales and provide a secure basis for comparison with extant taxa.Methods
The floral structure of several fossil specimens was studied by scanning electron microscopy (SEM), light microscopy of microtome thin sections and synchrotron-radiation X-ray tomographic microscopy (SRXTM). For direct comparisons with flowers of extant Ericales, selected floral features of Actinidiaceae and Clethraceae were studied with SEM.Key Results
Flowers of G. upatoiensis have five sepals with quincuncial aestivation, five free petals with quincuncial aestivation, 20–28 stamens arranged in a single series, extrorse anther orientation in the bud, ventral anther attachment and a tricarpellate, syncarpous ovary with three free styles and numerous small ovules on axile, protruding-diffuse and pendant placentae. The calyx is characterized by a conspicuous indumentum of large, densely arranged, multicellular and possibly glandular trichomes.Conclusions
Comparison with extant taxa provides clear evidence for a relationship with core Ericales comprised of the extant families Actinidiaceae, Roridulaceae, Sarraceniaceae, Clethraceae, Cyrillaceae and Ericaceae. Within this group, the most marked similarities are with extant Actinidiaceae and, to a lesser degree, with Clethraceae. More detailed analyses of the relationships of Glandulocalyx and other Ericales from the Late Cretaceous will require an improved understanding of the morphological features that diagnose particular extant groups defined on the basis of molecular data. 相似文献106.
Kashihara T Nakada T Shimojo H Horiuchi-Hirose M Gomi S Shibazaki T Sheng X Hirose M Hongo M Yamada M 《American journal of physiology. Heart and circulatory physiology》2012,302(8):H1645-H1654
L-type Ca(2+) channels (LTCCs) play an essential role in the excitation-contraction coupling of ventricular myocytes. We previously found that t-tubular (TT) LTCC current density was halved by the activation of protein phosphatase (PP)1 and/or PP2A, whereas surface sarcolemmal (SS) LTCC current density was increased by the inhibition of PP1 and/or PP2A activity in failing ventricular myocytes of mice chronically treated with isoproterenol (ISO mice). In the present study, we examined the possible involvement of inhibitory heterotrimeric G proteins (G(i/o)) in these abnormalities by chronically administrating pertussis toxin (PTX) to ISO mice (ISO + PTX mice). Compared with ISO mice, ISO + PTX mice exhibited significantly higher fractional shortening of the left ventricle. The expression level of Gα(i2) proteins was not altered by the treatment of mice with ISO and/or PTX. ISO + PTX myocytes had normal TT and SS LTCC current densities because they had higher and lower availability and/or open probability of TT and SS LTCCs than ISO myocytes, respectively. A selective PKA inhibitor, H-89, did not affect LTCC current densities in ISO + PTX myocytes. A selective PP2A inhibitor, fostriecin, did not affect SS or TT current density in control or ISO + PTX myocytes but significantly increased TT but not SS LTCC current density in ISO myocytes. These results indicate that chronic receptor-mediated activation of G(i/o) in vivo decreases basal TT LTCC activity by activating PP2A and increases basal SS LTCC activity by inhibiting PP1 without modulating PKA in heart failure. 相似文献
107.
Sekine KT Tomita R Takeuchi S Atsumi G Saitoh H Mizumoto H Kiba A Yamaoka N Nishiguchi M Hikichi Y Kobayashi K 《Molecular plant-microbe interactions : MPMI》2012,25(9):1219-1229
The N' gene of Nicotiana sylvestris and L genes of Capsicum plants confer the resistance response accompanying the hypersensitive response (HR) elicited by tobamovirus coat proteins (CP) but with different viral specificities. Here, we report the identification of the N' gene. We amplified and cloned an N' candidate using polymerase chain reaction primers designed from L gene sequences. The N' candidate gene was a single 4143 base pairs fragment encoding a coiled-coil nucleotide-binding leucine-rich repeat (LRR)-type resistance protein of 1,380 amino acids. The candidate gene induced the HR in response to the coexpression of tobamovirus CP with the identical specificity as reported for N'. Analysis of N'-containing and tobamovirus-susceptible N. tabacum accessions supported the hypothesis that the candidate is the N' gene itself. Chimera analysis between N' and L(3) revealed that their LRR domains determine the spectrum of their tobamovirus CP recognition. Deletion and mutation analyses of N' and L(3) revealed that the conserved sequences in their C-terminal regions have important roles but contribute differentially to the recognition of common avirulence proteins. The results collectively suggest that Nicotiana N' and Capsicum L genes, which most likely evolved from a common ancestor, differentiated in their recognition specificity through changes in the structural requirements for LRR function. 相似文献
108.
K Sato M Ishiai K Toda S Furukoshi A Osakabe H Tachiwana Y Takizawa W Kagawa H Kitao N Dohmae C Obuse H Kimura M Takata H Kurumizaka 《The EMBO journal》2012,31(17):3524-3536
Fanconi anaemia (FA) is a rare hereditary disorder characterized by genomic instability and cancer susceptibility. A key FA protein, FANCD2, is targeted to chromatin with its partner, FANCI, and plays a critical role in DNA crosslink repair. However, the molecular function of chromatin-bound FANCD2-FANCI is still poorly understood. In the present study, we found that FANCD2 possesses nucleosome-assembly activity in vitro. The mobility of histone H3 was reduced in FANCD2-knockdown cells following treatment with an interstrand DNA crosslinker, mitomycin C. Furthermore, cells harbouring FANCD2 mutations that were defective in nucleosome assembly displayed impaired survival upon cisplatin treatment. Although FANCI by itself lacked nucleosome-assembly activity, it significantly stimulated FANCD2-mediated nucleosome assembly. These observations suggest that FANCD2-FANCI may regulate chromatin dynamics during DNA repair. 相似文献
109.
Alkaline phosphatase catalyzes the hydrolysis of phosphomonoesters and is widely used in molecular biology techniques and
clinical diagnostics. We expressed a recombinant alkaline phosphatase of the marine bacterium, Cobetia marina, in Escherichia coli BL21 (DE3). The recombinant protein was purified with a specific activity of 12,700 U/mg protein, which is the highest activity
reported of any bacterial alkaline phosphatase studied to date. The molecular mass of the recombinant protein was 55–60 kDa,
as determined by SDS–PAGE, and was observed to be a dimer by gel filtration analysis. The enzyme was optimally active at 45°C
and the recombinant alkaline phosphatase efficiently hydrolyzed a phosphoric acid ester in luminescent and fluorescent substrates.
Therefore, this enzyme can be considered to be extremely useful as a label conjugated to an antibody. 相似文献
110.
Nishijima N Marusawa H Ueda Y Takahashi K Nasu A Osaki Y Kou T Yazumi S Fujiwara T Tsuchiya S Shimizu K Uemoto S Chiba T 《PloS one》2012,7(4):e35052