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961.
Guntupalli R Sorokulova I Krumnow A Pustovyy O Olsen E Vodyanoy V 《Biosensors & bioelectronics》2008,24(1):151-154
Staphylococcus aureus (S. aureus)-specific bacteriophage was used as a probe for detection of methicillin-resistant S. aureus (MRSA) in aqueous solution using a novel optical method. Biorecognition phage monolayers transferred to glass substrates using Langmuir-Blodgett (LB) technique were exposed individually to MRSA in solution at logarithmic concentrations ranging from 10(6) to 10(9)cfu/ml, and observed for real-time binding using a CytoVivatrade mark optical light microscope system. Results indicate that LB monolayers possessed high levels of elasticity (K), measuring 22 and 29mN/m for 10(9) and 10(11)pfu/ml phage concentrations, respectively. Near-instantaneous MRSA-phage binding produced 33+/-5%, 10+/-1%, 1.1+/-0.1%, and 0.09+/-0.01% coverage of the substrate that directly correlated to a decrease in MRSA concentrations of 10(9), 10(8), 10(7), and 10(6)cfu/ml. The exclusive selectivity of phage monolayers was verified with Salmonella enterica subsp. enterica serovar typhimurium (S. typhimurium) and Bacillus subtilis. 相似文献
962.
963.
Summary. N-alkyl-β-alanine oligomers (β-peptoids) with α-chiral side chains [(R)- or (S)-1-(phenylethyl)amino groups] were synthesized and analyzed by CD spectroscopy. These chiral β-peptoid homomers exhibited
chain-length-dependent and solvent-dependent ellipticity, strongly indicating the presence of a secondary structure in solution.
The CD behaviour was only slightly temperature-dependent upon heating, as also previously observed for stable α-peptoid helices
containing the same type of side chains. Thus, the data presented here comprise the first evidence for a chain length-dependent
secondary folding of compounds with this novel peptidomimetic backbone design. In addition, applicability of a novel hyphenated
technique, HPLC-SPE-NMR/MS, for analysis of crude SPPS reaction products was demonstrated.
Authors’ address: Dr. C. A. Olsen, Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen,
Universitetsparken 2, DK-2100 Copenhagen, Denmark; Present address: The Scripps Research Institute 相似文献
964.
Michael Hauschild Stig Irving Olsen Erik Hansen Anders Schmidt 《The International Journal of Life Cycle Assessment》2008,13(7):547-554
Background, aim and scope Land filling of materials with content of toxic metals or highly persistent organic compounds has posed a problem for life
cycle assessment (LCA) practitioners for many years. The slow release from the landfill entails a dilution in time, which
is dramatic compared to other emissions occurring in the life cycle, and with its focus on the emitted mass, LCA is poorly
equipped to handle this difference. As a consequence, the long-term emissions from landfills occurring over thousands of years
are often disregarded, which is unacceptable to many stakeholders considering the quantities of toxic substances that can
be present. On the other hand, inclusion of all future emissions (over thousands of years) in the inventories potentially
dominates all other impacts from the product system. The paper aims to present a pragmatic approach to address this dilemma.
Materials and methods Two new impact categories are introduced representing the stored ecotoxicity and stored human toxicity of the contaminants
remaining in the landfill after a ‘foreseeable’ time period of 100 years. The impact scores are calculated using the normal
characterisation factors for the ecotoxicity and human toxicity impact categories, and they represent the toxicity potentials
of what remains in the landfill after 100 years (hence the term ‘stored’ (eco)toxicity). Normalisation references are developed
for the stored toxicity categories based on Danish figures to support comparison with indicator scores for the conventional
environmental impact categories. In contrast to the scores for the conventional impact categories, it is uncertain to what
extent the stored toxicity scores represent emissions, which will occur at all. Guidance is given on how to reflect this uncertainty
in the weighting and interpretation of the scores.
Results and discussion In landfills and road constructions used to deposit residuals from incinerators, less than 1% of the content of metals is
leached within the first 100 years. The stored toxicity scores are therefore much higher than the conventional impact scores
that represent the actual emissions. Several examples are given illustrating the use and potential significance of the stored
toxicity categories.
Conclusions and perspectives The methodology to calculate stored human and ecotoxicity is a simple and pragmatic approach to address LCA’s problem of treating
the slow long-term emissions at very low concentrations appropriately. The problem resides in the inventory analysis and the
impact assessment, and the methodology circumvents the problem by converting it into a weighting and interpretation issue
accommodating the value-based discussion of how to weight potential effects in the far future.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
Michael HauschildEmail: |
965.
Spina bifida, or failure of the vertebrae to close at the midline, is a common congenital malformation in humans that is often synonymous with neural tube defects (NTDs). However, it is likely that other etiologies exist. Genetic disruption of platelet-derived growth factor receptor (PDGFR) alpha results in spina bifida, but the underlying mechanism has not been identified. To elucidate the cause of this birth defect in PDGFRalpha mutant embryos, we examined the developmental processes involved in vertebrae formation. Exposure of chick embryos to the PDGFR inhibitor imatinib mesylate resulted in spina bifida in the absence of NTDs. We next examined embryos with a tissue-specific deletion of the receptor. We found that loss of the receptor from chondrocytes did not recapitulate the spina bifida phenotype. By contrast, loss of the receptor from all sclerotome and dermatome derivatives or disruption of PDGFRalpha-driven phosphatidyl-inositol 3' kinase (PI3K) activity resulted in spina bifida. Furthermore, we identified a migration defect in the sclerotome as the cause of the abnormal vertebral development. We found that primary cells from these mice exhibited defects in PAK1 activation and paxillin localization. Taken together, these results indicate that PDGFRalpha downstream effectors, especially PI3K, are essential for cell migration of a somite-derived dorsal mesenchyme and disruption of receptor signaling in these cells leads to spina bifida. 相似文献
966.
Mertins P Eberl HC Renkawitz J Olsen JV Tremblay ML Mann M Ullrich A Daub H 《Molecular & cellular proteomics : MCP》2008,7(9):1763-1777
Because of their antagonistic catalytic functions, protein-tyrosine phosphatases (PTPs) and protein-tyrosine kinases act together to control phosphotyrosine-mediated signaling processes in mammalian cells. However, unlike for protein-tyrosine kinases, little is known about the cellular substrate specificity of many PTPs because of the lack of appropriate methods for the systematic and detailed analysis of cellular PTP function. Even for the most intensely studied, prototypic family member PTP1B many of its physiological functions cannot be explained by its known substrates. To gain better insights into cellular PTP1B function, we used quantitative MS to monitor alterations in the global tyrosine phosphorylation of PTP1B-deficient mouse embryonic fibroblasts in comparison with their wild-type counterparts. In total, we quantified 124 proteins containing 301 phosphotyrosine sites under basal, epidermal growth factor-, or platelet-derived growth factor-stimulated conditions. A subset of 18 proteins was found to harbor hyperphosphorylated phosphotyrosine sites in knock-out cells and was functionally linked to PTP1B. Among these proteins, regulators of cell motility and adhesion are overrepresented, such as cortactin, lipoma-preferred partner, ZO-1, or p120ctn. In addition, regulators of proliferation like p62DOK or p120RasGAP also showed increased cellular tyrosine phosphorylation. Physical interactions of these proteins with PTP1B were further demonstrated by using phosphatase-inactive substrate-trapping mutants in a parallel MS-based analysis. Our results correlate well with the described phenotype of PTP1B-deficient fibroblasts that is characterized by an increase in motility and reduced cell proliferation. The presented study provides a broad overview about phosphotyrosine signaling processes in mouse fibroblasts and, supported by the identification of various new potential substrate proteins, indicates a central role of PTP1B within cellular signaling networks. Importantly the MS-based strategies described here are entirely generic and can be used to address the poorly understood aspects of cellular PTP function. 相似文献
967.
The fucosylated ABH antigens, which constitute the molecular basis for the ABO blood group system, are also expressed in salivary secretions and gastrointestinal epithelia in individuals of positive secretor status; however, the biological function of the ABO blood group system is unknown. Gastric mucosa biopsies of 41 Rhesus monkeys originating from Southern Asia were analyzed by immunohistochemistry. A majority of these animals were found to be of blood group B and weak-secretor phenotype (i.e., expressing both Lewis a and Lewis b antigens), which are also common in South Asian human populations. A selected group of ten monkeys was inoculated with Helicobacter pylori and studied for changes in gastric mucosal glycosylation during a 10-month period. We observed a loss in mucosal fucosylation and concurrent induction and time-dependent dynamics in gastric mucosal sialylation (carbohydrate marker of inflammation), which affect H. pylori adhesion targets and thus modulate host-bacterial interactions. Of particular relevance, gastric mucosal density of H. pylori, gastritis, and sialylation were all higher in secretor individuals compared to weak-secretors, the latter being apparently "protected." These results demonstrate that the secretor status plays an intrinsic role in resistance to H. pylori infection and suggest that the fucosylated secretor ABH antigens constitute interactive members of the human and primate mucosal innate immune system. 相似文献
968.
Ostenfeld MS Høyer-Hansen M Bastholm L Fehrenbacher N Olsen OD Groth-Pedersen L Puustinen P Kirkegaard-Sørensen T Nylandsted J Farkas T Jäättelä M 《Autophagy》2008,4(4):487-499
A sigma-2 receptor ligand siramesine induces lysosomal leakage and cathepsin-dependent death of cancer cells in vitro and displays potent anti-cancer activity in vivo. The mechanism by which siramesine destabilizes lysosomes is, however, unknown. Here, we show that siramesine induces a rapid rise in the lysosomal pH that is followed by lysosomal leakage and dysfunction. The rapid accumulation of siramesine into cancer cell lysosomes, its ability to destabilize isolated lysosomes, and its chemical structure as an amphiphilic amine indicate that it is a lysosomotropic detergent. Notably, siramesine triggers also a substantial Atg6- and Atg7-dependent accumulation of autophagosomes that is associated with a rapid and sustained inhibition of mammalian target of rapamycin complex 1 (mTORC1; an inhibitor of autophagy). Siramesine fails, however, to increase the degradation rate of long-lived proteins. Thus, the massive accumulation of autophagosomes is likely to be due to a combined effect of activation of autophagy signaling and decreased autophagosome turnover. Importantly, pharmacological and RNA interference-based inhibition of autophagosome formation further sensitizes cancer cells to siramesine-induced cytotoxicity. These data identify siramesine as a lysosomotropic detergent that triggers cell death via a direct destabilization of lysosomes and cytoprotection by inducing the accumulation of autophagosomes. Threrefore, the combination of siramesine with inhibitors of autophagosome formation appears as a promising approach for future cancer therapy. 相似文献
969.
RNA interference of the BMPR-IB gene blocks BMP-2-induced osteogenic gene expression in human bone cells 总被引:1,自引:0,他引:1
We have previously shown that human bone cells express bone morphogenetic protein receptor-IB (BMPR-IB). However, little is known about the precise role of this receptor in the response of osteoblastic genes to the BMP in these cells. To determine BMPR-IB-dependent osteoblastic gene expression, the present study examined the effects of BMPR-IB knockdown on BMP-induced osteoblast-associated genes. BMPR-IB mRNA and protein were markedly suppressed by transfection of cells with BMPR-IB siRNA. Using three different bone cell samples, BMP-2 stimulation of alkaline phosphatase (ALP), osteocalcin (OC), distal-less homeobox-5 (Dlx5) and core binding factor alpha-1 (Cbfa1) was found to be specifically and significantly reduced in the BMPR-IB siRNA-transfected cultures compared with that of control cultures. Our study has provided evidence that BMPR-IB-dependent signaling plays a crucial role in BMP-2 up-regulation of the ALP, OC, Dlx5 and Cbfa1 genes in bone cells, suggesting a pivotal role of this receptor in BMP-2-induced osteoblast differentiation in vitro. These findings thus suggest the possibility that BMPR-IB could be a therapeutic target for enhancing bone regeneration in vivo. 相似文献
970.
Ubc9 sumoylation regulates SUMO target discrimination 总被引:1,自引:0,他引:1
Knipscheer P Flotho A Klug H Olsen JV van Dijk WJ Fish A Johnson ES Mann M Sixma TK Pichler A 《Molecular cell》2008,32(3):371-382