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排序方式: 共有645条查询结果,搜索用时 31 毫秒
121.
122.
Erzébeth Elékés Dorothee Jakobs F. Ulrich Schade 《FEMS immunology and medical microbiology》1993,6(1):13-20
Abstract The effects of several inhibitors of lipoxygenases were investigated in murine spleen cell cultures activated with endotoxin (lipopolysaccharide) It was found that these inhibitors interfere with the proliferative response of the cultures. Indomethacin, a specific cyclooxygenase inhibitor, had no such effect. Endotoxin induced the synthesis of tumour necrosis factor α in spleen cells which was prevented by treatment with a lipoxygenase inhibitor. The inhibition of the mitogenic effect of endotoxin could be reversed by addition of 13-hydroxyoctadecadienoic acid. This was not the case with leukotriene B4 and C4 or 15-hydroxyeicosatetraenoic acid. In contrast, these substances had inhibitory effects on the mitogenicity of spleen cells. It is suggested that 13-hydroxyoctadecadienoic acid is involved in the development of the mitogenic reaction, possibly on the level of tumour necrosis factor α production of macrophages present in the cultures. 相似文献
123.
Summary The mglB gene of Salmonella typhimurium LT2 coding for the galactose-binding protein (GBP) was sequenced. We compared the deduced amino acid sequence with the GBP sequence of Escherichia coli K12. The mature proteins differ in only 19 of 309 amino acid residues, corresponding to 94% homology. Analysis of the mglB control region by promoter-probe vectors revealed that two promoters, P1 and P2, constitute the mgl control region (P
mgl
). P1 and P2 function in a synergistic way. P1 is the main promoter of the operon; its activity is 20 times the activity of P2. Both promoters are activated by the cyclic adenosine monophosphate catabolite activator protein (cAMP/CAP) complex. While P1 is inactive in the absence of the cAMP/CAP complex, there is residual activity of P2 under these conditions. Studies on the inducibility of the mglBAEC operon using multicopy plasmid promoter-probe vectors were hampered by the titration of the mgl repressor resulting in a partially constitutive expression of the mgl operon. The results indicate that only P1 is responding to induction by D-fucose. A weak promoter, P
D
, within the P1 region but divergent to it was found. P
D
is neither stimulated by the cAMP/CAP complex nor by D-fucose. We cloned the gene located downstream to P
D
and found it to strongly repress the expression of the mgl operon. We termed this gene mglD. The presence of D-fucose abolished the repression caused by the plasmid-encoded mglD gene product.Abbreviations IPTG
isopropyl-1-thic--D-galatopyranoside
- ONPG
2-nitrophenyl--D-galatopyranoside
- XG
5-bromo-4-chloro-3-indolyl--D-galatopyranoside
- Kanr
Kanamycin resistance 相似文献
124.
Breitenbach Romy Silbernagl Dorothee Toepel Jörg Sturm Heinz Broughton William J. Sassaki Guilherme L. Gorbushina Anna A. 《Extremophiles : life under extreme conditions》2018,22(2):165-175
Extremophiles - Melanised cell walls and extracellular polymeric matrices protect rock-inhabiting microcolonial fungi from hostile environmental conditions. How extracellular polymeric substances... 相似文献
125.
126.
Abstract: The rat 5-hydroxytryptamine2C (5-HT2C ) receptor was identified as N -glycosylated polypeptide of 60-kDa apparent molecular mass using antibodies against its putative third and fourth (C-terminal) cytoplasmic domain. To show that the polypeptides detected on western blots and by immunoprecipitation represent the 5-HT2C receptor, binding studies of the 5-HT2C ligand [3 H]-mesulergine to immunoprecipitates from extracts of pig choroid plexus were performed. We demonstrate the presence of a signal sequence that was cleaved off during membrane insertion resulting in a 38-kDa polypeptide. During further maturation, the receptor was N -glycosylated at two sites via a 48-kDa intermediate. This intermediate was far more abundant in choroid plexus than in hippocampus and may represent an intracellular receptor reserve. After transfection of 5-HT2C cDNAs into cultured cells, polypeptides were observed that differed from the ones found in vivo due to abnormal N -glycosylation and possibly other alterations depending on the system used. Thus the 5-HT2C receptor expressed in cell lines may also differ in function from the receptor in its native tissue. 相似文献
127.
Preclinical cancer vaccine studies must address vaccine safety, immunogenicity, and efficacy, as well as mechanism of vaccine
action. Animal models of vaccines employing human tumor-associated antigen or epitopes (TAA, TAE) differ fundamentally from
those employing tumor-specific antigens or epitopes (TSA, TSE). TSA and TSE vaccines will most likely demonstrate similar
toxicity, immunogenicity, and efficacy in both tumor-bearing animals and patients. In contrast, TAA/TAE immunizations may
have to overcome a host’s immunological tolerance to TAA/TAE expressed not only on tumor, but also on normal tissues; immunity
to TAA/TAE will potentially target normal tissues and thus may induce autoimmunity. Various experimental models for human-derived
TAA/TAE vaccines have been developed. These models include transgenic mice, mice with severe combined immunodeficiency (SCID),
and non-human primates. Recently, unique animal models of TAA/TAE cancer vaccines have been developed, taking advantage of
the discovery of animal tissue antigens with significant sequence homologies to human TAA/TAE. These models mimic perhaps
most closely the situation in cancer patients. 相似文献
128.
Wolfgang Schmitt Stefan Odenbreit Dorothee Heuermann Rainer Haas 《Molecular genetics and genomics : MGG》1995,248(5):563-572
The RecA protein is a key enzyme involved in DNA recombination in bacteria. Using a polymerase chain reaction (PCR) amplification we cloned arecA homolog fromHelicobacter pylori. The gene revealed an open reading frame (ORF) encoding a putative protein of 37.6 kDa showing closest homology to theCampylobacter jejuni RecA (75.5% identity). A putative ribosome binding site and a near-consensus σ70 promoter sequence was found upstream ofrec A. A second ORF, encoding a putative protein with N-terminal sequence homology to prokaryotic and eukaryotic enolases, is located directly downstream ofrecA. Compared to the wild-type strains, isogenicH. pylori recA deletion mutants of strains 69A and NCTC11637 displayed increased sensitivity to ultraviolet light and abolished general homologous recombination. The recombinantH. pylori RecA protein produced inEscherichia coli strain GC6 (recA ?) was 38 kDa in size but inactive in DNA repair, whereas the corresponding protein inH. pylori 69A migrated at the greater apparent molecular weight of approx. 40 kDa in SDS-polyacrylamide gels. However, complementation of theH. pylori mutant using the clonedrecA gene on a shuttle vector resulted in a RecA protein of the original size and fully restored the general functions of the enzyme. These data can be best explained by a modification of RecA inH. pylori which is crucial for its function. The potential modification seems not to occur when the protein is produced inE. coli, giving rise to a smaller but inactive protein. 相似文献
129.
Holger Herlyn 《Organisms Diversity & Evolution》2016,16(4):689-713
Molecular analyses of the last decades helped solving the major open questions on the external and internal phylogenetic relationships of primates. The present review uses these data for the inference of character evolution along the branches of the primate tree. Altogether, more than 200 evolutionary changes in hard and soft tissue anatomy/morphology, behavior, physiology, and protein constitution are presented in the context of their functional relevance and adaptive value. The compilation focuses on primates as a whole and on the higher-ranked primate subtaxa with living representatives: Strepsirhini: Lorisiformes, Galagidae, Lorisidae, Lemuriformes; Haplorhini: Tarsioidea, Anthropoidea, Platyrrhini, Atelidae + Cebidae, Atelidae, Cebidae, Aotinae, Callithrichinae, Cebinae, Pitheciidae, Pithecinae, Catarrhini, Cercopithecoidea, Cercopithecinae, Colobinae, Colobini, and Hominoidea. Within Hominoidea character evolution is traced down to more peripheral branches: Hylobatidae, Hominidae, Pongo, Homininae, Gorilla, Pan + Homo, Pan, and modern humans. Character states in extinct representatives of Plesiadapiformes, Omomyoidea, Propliopithecidae, Hominini, etc. are always taken into account; they are presented in detail whenever character-state distribution in living species is ambiguous or misleading. The taxonomic sample and the characters included combine to a phylogenetic system that illustrates primate evolution and diversity. The data presented additionally provide a detailed picture of the evolutionary steps and trends involved in hominization. Reflections on the frequently underestimated role of polymorphisms in phylogenetic analyses complete the survey. 相似文献
130.
Joshua X. Wang Mizuho Fukunaga-Kalabis Meenhard Herlyn 《Journal of cell communication and signaling》2016,10(3):191-196
In the vertebrate embryo, melanocytes arise from the neural crest, migrate to and colonize the basal layer within the skin and skin appendages. Post-migratory melanocytes are securely attached to the basement membrane, and their morphology, growth, adhesion, and migration are under control of neighboring keratinocytes. Melanoma is a malignant tumor originated from melanocytes or their progenitor cells. During melanocyte transformation and melanoma progression, melanocytes lose their interactions with keratinocytes, resulting in uncontrolled proliferation and invasion of the malignant cells. Melanoma cells at the advanced stages often lack melanocytic features and resemble multipotent progenitors, which are a potential melanocyte reservoir in human skin. In this mini-review, we will summarize findings on cell-cell interactions that are responsible for normal melanocyte homeostasis, stem cell self-renewal, and differentiation. Our ultimate goal is to define molecules and pathways, which are essential for normal cell-cell interactions but deregulated in melanoma formation and progression. 相似文献