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排序方式: 共有339条查询结果,搜索用时 15 毫秒
31.
Masahiro Uchida Shuji Hanai Naoya Uematsu Kazunobu Sawamoto Hideyuki Okano Masanao Miwa Kazuhiko Uchida 《The Journal of biological chemistry》2002,277(8):6696-6702
Poly(ADP-ribose) polymerase (PARP) may play important roles in nuclear events such as cell cycle, cell proliferation, and maintenance of chromosomal stability. However, the exact biological role played by PARP or how PARP is involved in these cellular functions is still unclear. To elucidate the biological functions of PARP in vivo, we have constructed transgenic flies that overexpress Drosophila PARP in the developing eye primordia. These flies showed mild roughening of the normally smooth ommatidial lattice and tissue polarity disruption caused by improper rotation and chirality of the ommatidia. To clarify how this phenotypical change was induced, here we analyzed transgenic flies overexpressing PARP in the developing eye, embryo, and adult in detail. PARP mRNA level and the phenotype were enhanced in flies carrying more copies of the transgene. Developing eyes from third instar larvae were analyzed by using the neural cell marker to examine the involvement of PARP in cell fate. Morphological disorder of non-neuronal accessory cells was observed in PARP transgenic flies. Interestingly, overexpression of PARP did not interfere with the cell cycle or apoptosis, but it did disrupt the organization of cytoskeletal F-actin, resulting in aberrant cell and tissue morphology. Furthermore, heat-induced PARP expression disrupted organization of cytoskeletal F-actin in embryos and tissue polarity in adult flies. Because these phenotypes closely resembled mutants or transgenic flies of the tissue polarity genes, genetic interaction of PARP with known tissue polarity genes was examined. Transgenic flies expressing either PARP or RhoA GTPase in the eye were crossed, and co-expression of PARP suppressed the effect of RhoA GTPase. Our results indicate that PARP may play a role in cytoskeletal or cytoplasmic events in developmental processes of Drosophila. 相似文献
32.
It has been demonstrated that Saccharomyces cerevisiae Vam6p/Vps39p plays a critical role in the tethering steps of vacuolar membrane fusion by facilitating guanine nucleotide exchange on small guanosine triphosphatase (GTPase) Vam4p/Ypt7p. We report here the identification and characterization of a novel protein in Aspergillus nidulans, AvaB, that exhibits similarity to Vam6p/Vps39p and plays a critical role in vacuolar morphogenesis in A. nidulans. AvaB is comprised of 1058 amino acids with amino-terminal citron homology (CNH) and central clathrin homology (CLH) domains, as observed for other Vam6p/Vps39p family proteins. Disruption of avaB in A. nidulans resulted in the fragmentation of vacuoles and reduced growth rate under various growth conditions, implying its importance in maintaining vacuolar morphology and function. Yeast two-hybrid analysis demonstrated the interaction of AvaB with AvaA, a Vam4p/Ypt7p homolog in A. nidulans, as well as the homooligomer formation of AvaB, suggesting that AvaB performs its function through hetero- or homophilic protein-protein interactions. 相似文献
33.
Phylogenetic relationships of the three lygosomine skink genera occurring both in the Old World and the New World (Mabuya, Scincella and Sphenomorphus) were inferred from mitochondrial DNA sequence of 12S and 16S rRNA genes. Results strongly suggested the non-monophyly for any of these three genera. Within the Mabuya group, Asian members appear to have diverged first, leaving the Neotropical and the Afro-Malagasy Mabuya as sister groups. These relationships, together with the absence of extant or fossil representatives of the Mabuya group from North America, strongly suggest the trans-Atlantic dispersals of Mabuya from Africa to Neotropics. Our results also indicated a closer affinity of the New World Scincella with the New World Sphenomorphus than with the Old World Scincella. Such relationships suggest the trans-Beringian dispersal of the common ancestor from Asia and its subsequent divergence into the North American Scincella and the Neotropical Sphenomorphus. 相似文献
34.
We characterized the resistance of the common bean cv. Jolanda to Clover yellow vein virus no. 30 (ClYVV). After inoculation, the virus was detected in neither inoculated nor upper leaves, suggesting that the resistance operates at either the viral replication or cell-to-cell movement level. To analyze the mechanism of resistance, we developed a green fluorescent protein (GFP)-tagged ClYVV, and monitored GFP fluorescence at sites of infection on ClYVV-inoculated leaves. No GFP fluorescence was detected in Jolanda, whereas its expression in single cells and spread on inoculated leaves were observed clearly in susceptible cultivars. ClYVV-introduced Jolanda cells were found to be still viable; therefore, it is unlikely that the restriction of multiplication was due to rapid cell death. Genetic analysis indicated that a single recessive locus controlled the resistant phenotype of Jolanda. We designated this locus desc (determinant of susceptibility to ClYVV). Meanwhile, a spontaneous mutant virus that overcomes the resistance (ClYVV-Br) was isolated. Inoculation assays using chimeric viruses suggested that a viral genome-linked protein (VPg) might be the avirulence determinant. The resistance mechanism may be associated with the role of VPg in the viral infection cycle. 相似文献
35.
Zhang MR Maeda J Furutsuka K Yoshida Y Ogawa M Suhara T Suzuki K 《Bioorganic & medicinal chemistry letters》2003,13(2):201-204
We synthesized and evaluated N-(5-fluoro-2-phenoxyphenyl)-N-(2-[(18)F]fluoromethyl-5-methoxybenzyl)acetamide ([(18)F]-FMDAA1106) and N-(5-fluoro-2-phenoxyphenyl)-N-(2-[(18)F]fluoroethyl-5-methoxybenzyl)acetamide ([(18)F]FEDAA1106) as two potent radioligands for peripheral benzodiazepine receptors (PBR). [(18)F]FMDAA1106 and [(18)F]FEDAA1106 were respectively synthesized by fluoroalkylation of the desmethyl precursor DAA1123 with [(18)F]FCH(2)I and [(18)F]FCH(2)CH(2)Br. Ex vivo autoradiograms of [(18)F]FMDAA1106 and [(18)F]FEDAA1106 binding sites in the rat brains revealed that a high radioactivity was present in the olfactory bulb, the highest PBR density region in the brain. 相似文献
36.
The orotidine-5′-phosphate decarboxylase gene of Saccharomyces exiguus Yp74L-3 was cloned as a DNA fragment complementing a ura4 mutation of this yeast. The coding region of the gene is 807 bp in length, and represents 68.7% similarity to the corresponding
gene of S. cerevisiae (URA3). The cloned URA4 gene was shown to be located on the 790-kbp Chromosome (chr) VIII of S. exiguus Yp74L-3. The neighbor-joining phylogenetic tree based on the orotidine-5′-phosphate decarboxylase coding sequences indicates
that S. exiguus Yp74L-3 is closely related to Kluyveromyces yeasts, as well as to a S. cerevisiae laboratory strain.
Received: 4 February 2000 / Accepted: 3 July 2000 相似文献
37.
38.
Foragers of the Japanese honeybee (Apis cerana japonica) were attracted by flowers of an oriental orchid (Cymbidium floribundum) and were observed to carry the pollinia on their scutella. After the removal of pollinia from the flowers, their labial color changed from white to reddish brown. Both artificial removal of pollinia and ethrel treatment of the flowers also induced this labial color change. Labia in color-changed flowers showed a decreased reflectance of wavelengths less than 670 nm compared to control intact flower. Both reflectance irradiance spectra and ultraviolet photographs showed that only the nectar guide in white (unchanged) flowers reflected ultraviolet light, and that this reflectance decreased with labial color change. Dual choice experiments showed that the honeybee foragers preferentially visited flowers having white labia rather than reddish brown. We suggest that Japanese honeybees discriminate between the floral phases of C. floribundum using color vision. 相似文献
39.
Synthesis of 9-β-d-glucopyranosyl-adenine-6′-phosphate is described. The method developed here involves the process of condensation of base (chloromercuri-6-benzamidopurine) (I) with phosphorylated sugar (2,3,4-tri-O-acetyl-6-diphenylphosphoryl-α-d-glucopyranosyl bromide) (II). This reaction gives crystalline 6-benzamido-9-(2′,3′,4′-tri-O-acetyl-6′-diphenylphosphoryl-β-d-glucopyranosyl)-purine (III) in high yield, which is converted to the desired nucleotide by alkaline hydrolysis. 相似文献