全文获取类型
收费全文 | 398篇 |
免费 | 29篇 |
专业分类
427篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 9篇 |
2021年 | 10篇 |
2020年 | 5篇 |
2019年 | 8篇 |
2018年 | 4篇 |
2017年 | 8篇 |
2016年 | 13篇 |
2015年 | 19篇 |
2014年 | 21篇 |
2013年 | 20篇 |
2012年 | 45篇 |
2011年 | 33篇 |
2010年 | 30篇 |
2009年 | 14篇 |
2008年 | 29篇 |
2007年 | 26篇 |
2006年 | 27篇 |
2005年 | 20篇 |
2004年 | 30篇 |
2003年 | 18篇 |
2002年 | 18篇 |
2001年 | 3篇 |
1999年 | 4篇 |
1997年 | 3篇 |
1985年 | 1篇 |
1938年 | 1篇 |
1934年 | 1篇 |
1929年 | 2篇 |
1918年 | 1篇 |
排序方式: 共有427条查询结果,搜索用时 15 毫秒
81.
Elisabeth M. Meulenbroek Diana Wouters Sacha Zeerleder 《Journal of visualized experiments : JoVE》2014,(83)
Antibodies against red blood cells (RBCs) can lead to complement activation resulting in an accelerated clearance via complement receptors in the liver (extravascular hemolysis) or leading to intravascular lysis of RBCs. Alloantibodies (e.g. ABO) or autoantibodies to RBC antigens (as seen in autoimmune hemolytic anemia, AIHA) leading to complement activation are potentially harmful and can be - especially when leading to intravascular lysis - fatal1. Currently, complement activation due to (auto)-antibodies on RBCs is assessed in vitro by using the Coombs test reflecting complement deposition on RBC or by a nonquantitative hemolytic assay reflecting RBC lysis1-4. However, to assess the efficacy of complement inhibitors, it is mandatory to have quantitative techniques. Here we describe two such techniques. First, an assay to detect C3 and C4 deposition on red blood cells that is induced by antibodies in patient serum is presented. For this, FACS analysis is used with fluorescently labeled anti-C3 or anti-C4 antibodies. Next, a quantitative hemolytic assay is described. In this assay, complement-mediated hemolysis induced by patient serum is measured making use of spectrophotometric detection of the released hemoglobin. Both of these assays are very reproducible and quantitative, facilitating studies of antibody-induced complement activation. 相似文献
82.
A DIGE analysis of developing poplar leaves subjected to ozone reveals major changes in carbon metabolism 总被引:4,自引:0,他引:4
Bohler S Bagard M Oufir M Planchon S Hoffmann L Jolivet Y Hausman JF Dizengremel P Renaut J 《Proteomics》2007,7(10):1584-1599
Tropospheric ozone pollution is described as having major negative effects on plants, compromising plant survival. Carbon metabolism is especially affected. In the present work, the effects of chronic ozone exposure were evaluated at the proteomic level in developing leaves of young poplar plants exposed to 120 ppb of ozone for 35 days. Soluble proteins (excluding intrinsic membrane proteins) were extracted from leaves after 3, 14 and 35 days of ozone exposure, as well as 10 days after a recovery period. Proteins (pI 4 to 7) were analyzed by 2-D DIGE experiments, followed by MALDI-TOF-TOF identification. Additional observations were obtained on growth, lesion formation, and leaf pigments analysis. Although treated plants showed large necrotic spots and chlorosis in mature leaves, growth decreased only slightly and plant height was not affected. The number of abscised leaves was higher in treated plants, but new leaf formation was not affected. A decrease in chlorophylls and lutein contents was recorded. A large number of proteins involved in carbon metabolism were identified. In particular, proteins associated with the Calvin cycle and electron transport in the chloroplast were down-regulated. In contrast, proteins associated with glucose catabolism increased in response to ozone exposure. Other identified enzymes are associated with protein folding, nitrogen metabolism and oxidoreductase activity. 相似文献
83.
Direct detection of soil-bound prions 总被引:1,自引:0,他引:1
Scrapie and chronic wasting disease are contagious prion diseases affecting sheep and cervids, respectively. Studies have indicated that horizontal transmission is important in sustaining these epidemics, and that environmental contamination plays an important role in this. In the perspective of detecting prions in soil samples from the field by more direct methods than animal-based bioassays, we have developed a novel immuno-based approach that visualises in situ the major component (PrP(Sc)) of prions sorbed onto agricultural soil particles. Importantly, the protocol needs no extraction of the protein from soil. Using a cell-based assay of infectivity, we also report that samples of agricultural soil, or quartz sand, acquire prion infectivity after exposure to whole brain homogenates from prion-infected mice. Our data provide further support to the notion that prion-exposed soils retain infectivity, as recently determined in Syrian hamsters intracerebrally or orally challenged with contaminated soils. The cell approach of the potential infectivity of contaminated soil is faster and cheaper than classical animal-based bioassays. Although it suffers from limitations, e.g. it can currently test only a few mouse prion strains, the cell model can nevertheless be applied in its present form to understand how soil composition influences infectivity, and to test prion-inactivating procedures. 相似文献
84.
PepSplice: cache-efficient search algorithms for comprehensive identification of tandem mass spectra
Roos FF Jacob R Grossmann J Fischer B Buhmann JM Gruissem W Baginsky S Widmayer P 《Bioinformatics (Oxford, England)》2007,23(22):3016-3023
MOTIVATION: Tandem mass spectrometry allows for high-throughput identification of complex protein samples. Searching tandem mass spectra against sequence databases is the main analysis method nowadays. Since many peptide variations are possible, including them in the search space seems only logical. However, the search space usually grows exponentially with the number of independent variations and may therefore overwhelm computational resources. RESULTS: We provide fast, cache-efficient search algorithms to screen large peptide search spaces including non-tryptic peptides, whole genomes, dozens of posttranslational modifications, unannotated point mutations and even unannotated splice sites. All these search spaces can be screened simultaneously. By optimizing the cache usage, we achieve a calculation speed that closely approaches the limits of the hardware. At the same time, we control the size of the overall search space by limiting the combinations of variations that can co-occur on the same peptide. Using a hypergeometric scoring scheme, we applied these algorithms to a dataset of 1 420 632 spectra. We were able to identify a considerable number of peptide variations within a modest amount of computing time on standard desktop computers. 相似文献
85.
86.
Siezen RJ Francke C Renckens B Boekhorst J Wels M Kleerebezem M van Hijum SA 《Journal of bacteriology》2012,194(1):195-196
There is growing interest in the beneficial effects of Lactobacillus plantarum on human health. The genome of L. plantarum WCFS1, first sequenced in 2001, was resequenced using Solexa technology. We identified 116 nucleotide corrections and improved function prediction for nearly 1,200 proteins, with a focus on metabolic functions and cell surface-associated proteins. 相似文献
87.
Le PT Cheng H Ninkovic S Plewe M Huang X Wang H Bagrodia S Sun S Knighton DR LaFleur Rogers CM Pannifer A Greasley S Dalvie D Zhang E 《Bioorganic & medicinal chemistry letters》2012,22(15):5098-5103
Lead optimization efforts that employed structure base drug design and physicochemical property based optimization leading to the discovery of a novel series of 4-methylpyrido pyrimidinone (MPP) are discussed. Synthesis and profile of 1, a PI3Kα/mTOR dual inhibitor, is highlighted. 相似文献
88.
89.
P Sacha J Jaworowska D Ojdana P Wieczorek S Czaban E Tryniszewska 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》2012,50(2):322-324
The aim of this study was to investigate the prevalence of the aacA4 gene in a population of multidrug resistant strains of P. aeruginosa isolated from bronchial secretions obtained from the Intensive Therapy Unit (ITU). Twelve MDR isolates were tested for antibiotic susceptibility and the presence of the aacA4 gene. In this study, 58.3% of the strains contained (6')-Ib' aminoglycoside acetyltransferase gene. All of the studied strains (aacA4-positive and aacA4-negative) were susceptible only to colistine (100%). Among other antibiotics, the lowest resistance rates were those shown against ceftazidime (14.3% to 20%) and imipenem (28.6% to 40%). Our studies frequently revealed the presence of the aacA4 gene as a factor responsible for resistance; it is probable that other mechanisms of resistance to aminoglycoside antibiotics also occurred. 相似文献
90.
Mutational spectrum of D-bifunctional protein deficiency and structure-based genotype-phenotype analysis 下载免费PDF全文
Ferdinandusse S Ylianttila MS Gloerich J Koski MK Oostheim W Waterham HR Hiltunen JK Wanders RJ Glumoff T 《American journal of human genetics》2006,78(1):112-124
D-bifunctional protein (DBP) deficiency is an autosomal recessive inborn error of peroxisomal fatty acid oxidation. The clinical presentation of DBP deficiency is usually very severe, but a few patients with a relatively mild presentation have been identified. In this article, we report the mutational spectrum of DBP deficiency on the basis of molecular analysis in 110 patients. We identified 61 different mutations by DBP cDNA analysis, 48 of which have not been reported previously. The predicted effects of the different disease-causing amino acid changes on protein structure were determined using the crystal structures of the (3R)-hydroxyacyl-coenzyme A (CoA) dehydrogenase unit of rat DBP and the 2-enoyl-CoA hydratase 2 unit and liganded sterol carrier protein 2-like unit of human DBP. The effects ranged from the replacement of catalytic amino acid residues or residues in direct contact with the substrate or cofactor to disturbances of protein folding or dimerization of the subunits. To study whether there is a genotype-phenotype correlation for DBP deficiency, these structure-based analyses were combined with extensive biochemical analyses of patient material (cultured skin fibroblasts and plasma) and available clinical information on the patients. We found that the effect of the mutations identified in patients with a relatively mild clinical and biochemical presentation was less detrimental to the protein structure than the effect of mutations identified in those with a very severe presentation. These results suggest that the amount of residual DBP activity correlates with the severity of the phenotype. From our data, we conclude that, on the basis of the predicted effect of the mutations on protein structure, a genotype-phenotype correlation exists for DBP deficiency. 相似文献