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21.
Complex coacervation is a phenomenon of phase separation that may occur in a solution of positively and negatively charged polyions. The resulting two phases are distinguished by the total concentration of both polyions, with the concentrated phase often containing vesicular structures composed of the two polyelectrolytes. We have used this phenomenon in an attempt to-prepare a hemoglobin-based red blood cell analog. Hemoglobin-containing coacervate vesicles have been prepared from gelatin A and the polyanionic carbohydrates acacia, pectin, or dextranstilfate. Hemoglobin seems to be anchored into the vesicle walls through interaction of its polyanion binding site with the negatively charged residues on the carbohydrates. Oxygen binding by the immobilized HbA is reversible and cooperative, with p50 values at 20 degrees C of 2.8, 6, and 24 mm Hg for the acacia- (pH 7.5), pectin- (pH 6.6), and dextransulfate-(pH 6.6) derived coacervates. Kinetic studies on CO binding show that the rate of CO uptake by the coacervates (t((1/2)) = 13-27 ms at 0.5 mM CO) is similar to that of human erythrocytes.The HbA-containing coacervates slowly dissolve in isotonic salt solutions (145 mM NaCl, pH 7.4), but they can be stabilized by treatment with glutaraldehyde. Oxygen binding by HbA incorporated into the stabilized coacervates derived from dextran sulfate is very similar to oxy gen binding by human red blood cells: p50 = 26 mm Hg and n = 1.89 at 37 degrees C in isotonic salt. These results show how a novel approach, based on an old concept, has led to the preparation of immobilized HbA, with functional properties similar to those of intraerythrocytic HbA. 相似文献
22.
Endocytosis of lactate dehydrogenase isoenzyme M4 in rats in vivo. Experiments with enzyme labelled with O-(4-diazo-3,5-di[125I]iodobenzoyl)sucrose. 总被引:3,自引:3,他引:0
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A S De Jong A M Duursma J M Bouma M Gruber A Brouwer D L Knook 《The Biochemical journal》1982,202(3):655-660
1. Pig lactate dehydrogenase isoenzyme M4 was labelled with O-(4-diazo-3,5-di[125I]iodobenzoyl)sucrose and injected intravenously into rats. Previous work has shown that this label does not influence the clearance of the enzyme (half-life about 26 min) and that it is retained within the lysosomes for several hours after endocytosis and breakdown of the protein [De Jong, Bouma & Gruber (1981) Biochem. J. 198, 45--51]. 2. The distribution of the radioactivity over a large number of tissues was determined 2 h after injection. A high percentage of the injected dose was found in liver (41%), spleen (10%) and bone including marrow (21%). 3. Autoradiography indicated uptake of the enzyme mainly by Kupffer cells of the liver, by spleen macrophages and by bone marrow macrophages. 4. Liver cells were isolated 1 h after injection of the enzyme. Kupffer cells, endothelial cells and parenchymal cells were found to endocytose the enzyme at rates corresponding to 4230, 35 and 25 ml of plasma/day per g of cell protein, respectively. 5. Previous injection of carbon particles greatly reduced the uptake of the enzyme by liver and spleen, but the uptake by bone marrow was not significantly changed. 相似文献
23.
D. W. Sundstrom H. E. Klei R. W. Coughlin G. J. Biederman C. A. Brouwer 《Biotechnology and bioengineering》1981,23(3):473-485
The production of sugars by enzymatic hydrolysis of cellulose is a multistep process which includes conversion of the intermediate cellobiose to glucose by β-glucosidase. Aside from its role as an intermediate, cellobiose inhibits the endoglucanase components of typical cellulase enzyme systems. Because these enzyme systems often contain insufficient concentrations of β-glucosidase to prevent accumulation of inhibitory cellobiose, this research investigated the use of supplemental immobilized β-glucosidase to increase yield of glucose. Immobilized β-glucosidase from Aspergillus phoenicis was produced by sorption at controlled-pore alumina with about 90% activity retention. The product lost only about 10% of the original activity during an on-stream reaction period of 500 hr with cellobiose as substrate; maximum activity occurred near pH 3.5 and the apparent activation energy was about 11 kcal/mol. The immobilized β-glucosidase was used together with Trichoderma reesei cellulase to hydrolyze cellulosic materials, such as Solka Floc, corn stove and exploded wood. Increased yields of glucose and greater conversions of cellobiose of glucose were observed when the reaction systems contained supplemental immobilized β-glucosidase. 相似文献
24.
25.
Ingeborg A. Brouwer Johanna M. Geleijnse Veronique M. Klaasen Liesbeth A. Smit Erik J. Giltay Janette de Goede Annemieke C. Heijboer Daan Kromhout Martijn B. Katan 《PloS one》2013,8(12)
Background
Alpha linolenic acid (ALA) is the major omega-3 fatty acid in the diet. Evidence on health effects of ALA is not conclusive, but some observational studies found an increased risk of prostate cancer with higher intake of ALA. We examined the effect of ALA supplementation on serum concentrations of prostate-specific antigen (PSA), a biomarker for prostate cancer.Methods
The Alpha Omega Trial (ClinicalTrials.gov Identifier: ) was a double-blind, placebo-controlled trial of ALA and the fish fatty acids eicosapentanoic acid (EPA) and docosahexanoic acid (DHA) on the recurrence of cardiovascular disease, using a 2×2 factorial design. Blood was collected at the start and the end of the intervention period. The present analysis included 1622 patients with a history of a myocardial infarction, aged 60–80 years with an initial PSA concentration <4 ng/mL. They received either 2 g per day of ALA or placebo in margarine spreads for 40 months. T-tests and logistic regression were used to assess the effects of ALA supplementation on changes in serum PSA (both continuously and as a dichotomous outcome, cut-off point: >4 ng/mL). NCT00127452Findings
Mean serum PSA increased by 0.42 ng/mL on placebo (n = 815) and by 0.52 ng/mL on ALA (n = 807), a difference of 0.10 (95% confidence interval: −0.02 to 0.22) ng/mL (P = 0·12). The odds ratio for PSA rising above 4 ng/mL on ALA versus placebo was 1.15 (95% CI: 0.84–1.58).Interpretation
An additional amount of 2 g of ALA per day increased PSA by 0.10 ng/mL, but the confidence interval ranged from −0.02 to 0.22 ng/mL and included no effect. Therefore, more studies are needed to establish whether or not ALA intake has a clinically significant effect on PSA or prostate cancer.Trial registration information
ClinicalTrials.gov; Identifier: . URL: http://www.clinicaltrials.gov/ct2/show/ NCT00127452. NCT00127452相似文献26.
Candy Kumps Annelies Fieuw Pieter Mestdagh Bj?rn Menten Steve Lefever Filip Pattyn Sara De Brouwer Tom Sante Johannes Hubertus Schulte Alexander Schramm Nadine Van Roy Tom Van Maerken Rosa Noguera Valérie Combaret Christine Devalck Frank Westermann Geneviève Laureys Angelika Eggert Jo Vandesompele Katleen De Preter Frank Speleman 《PloS one》2013,8(1)
Neuroblastoma is an embryonic tumor arising from immature sympathetic nervous system cells. Recurrent genomic alterations include MYCN and ALK amplification as well as recurrent patterns of gains and losses of whole or large partial chromosome segments. A recent whole genome sequencing effort yielded no frequently recurring mutations in genes other than those affecting ALK. However, the study further stresses the importance of DNA copy number alterations in this disease, in particular for genes implicated in neuritogenesis. Here we provide additional evidence for the importance of focal DNA copy number gains and losses, which are predominantly observed in MYCN amplified tumors. A focal 5 kb gain encompassing the MYCN regulated miR-17∼92 cluster as sole gene was detected in a neuroblastoma cell line and further analyses of the array CGH data set demonstrated enrichment for other MYCN target genes in focal gains and amplifications. Next we applied an integrated genomics analysis to prioritize MYCN down regulated genes mediated by MYCN driven miRNAs within regions of focal heterozygous or homozygous deletion. We identified RGS5, a negative regulator of G-protein signaling implicated in vascular normalization, invasion and metastasis, targeted by a focal homozygous deletion, as a new MYCN target gene, down regulated through MYCN activated miRNAs. In addition, we expand the miR-17∼92 regulatory network controlling TGFß signaling in neuroblastoma with the ring finger protein 11 encoding gene RNF11, which was previously shown to be targeted by the miR-17∼92 member miR-19b. Taken together, our data indicate that focal DNA copy number imbalances in neuroblastoma (1) target genes that are implicated in MYCN signaling, possibly selected to reinforce MYCN oncogene addiction and (2) serve as a resource for identifying new molecular targets for treatment. 相似文献
27.
Yara Koréissi-Dembélé Nadia Fanou-Fogny Diego Moretti Stephan Schuth Romain A. M. Dossa Ines Egli Michael B. Zimmermann Inge D. Brouwer 《PloS one》2013,8(10)
Low iron and high phytic acid content make fonio based meals a poor source of bioavailable iron. Phytic acid degradation in fonio porridge using whole grain cereals as phytase source and effect on iron bioavailability when added to iron fortified fonio meals were investigated. Grains, nuts and seeds collected in Mali markets were screened for phytic acid and phytase activity. We performed an iron absorption study in Beninese women (n = 16), using non-dephytinised fonio porridge (FFP) and dephytinised fonio porridge (FWFP; 75% fonio-25% wheat), each fortified with 57Fe or 58Fe labeled FeSO4. Iron absorption was quantified by measuring the erythrocyte incorporation of stable iron isotopes. Phytic acid varied from 0.39 (bambara nut) to 4.26 g/100 g DM (pumpkin seed), with oilseeds values higher than grains and nuts. Phytase activity ranged from 0.17±1.61 (fonio) to 2.9±1.3 phytase unit (PU) per g (whole wheat). Phytic acid was almost completely degraded in FWFP after 60 min of incubation (pH≈5.0, 50°C). Phytate∶iron molar ratios decreased from 23.7∶1 in FFP to 2.7∶1 in FWFP. Iron fortification further reduced phytate∶iron molar ratio to 1.9∶1 in FFP and 0.3∶1 in FWFP, respectively. Geometric mean (95% CI) iron absorption significantly increased from 2.6% (0.8–7.8) in FFP to 8.3% (3.8–17.9) in FWFP (P<0.0001). Dephytinisation of fonio porridge with intrinsic wheat phytase increased fractional iron absorption 3.2 times, suggesting it could be a possible strategy to decrease PA in cereal-based porridges. 相似文献
28.
Margreet J. Oosterkamp Teun Veuskens Flávia Talarico Saia Sander A. B. Weelink Lynne A. Goodwin Hajnalka E. Daligault David C. Bruce John C. Detter Roxanne Tapia Cliff S. Han Miriam L. Land Loren J. Hauser Alette A. M. Langenhoff Jan Gerritse Willem J. H. van Berkel Dietmar H. Pieper Howard Junca Hauke Smidt Gosse Schraa Mark Davids Peter J. Schaap Caroline M. Plugge Alfons J. M. Stams 《PloS one》2013,8(6)
The genomes of the Betaproteobacteria Alicycliphilus denitrificans strains BC and K601T have been sequenced to get insight into the physiology of the two strains. Strain BC degrades benzene with chlorate as electron acceptor. The cyclohexanol-degrading denitrifying strain K601T is not able to use chlorate as electron acceptor, while strain BC cannot degrade cyclohexanol. The 16S rRNA sequences of strains BC and K601T are identical and the fatty acid methyl ester patterns of the strains are similar. Basic Local Alignment Search Tool (BLAST) analysis of predicted open reading frames of both strains showed most hits with Acidovorax sp. JS42, a bacterium that degrades nitro-aromatics. The genomes include strain-specific plasmids (pAlide201 in strain K601T and pAlide01 and pAlide02 in strain BC). Key genes of chlorate reduction in strain BC were located on a 120 kb megaplasmid (pAlide01), which was absent in strain K601T. Genes involved in cyclohexanol degradation were only found in strain K601T. Benzene and toluene are degraded via oxygenase-mediated pathways in both strains. Genes involved in the meta-cleavage pathway of catechol are present in the genomes of both strains. Strain BC also contains all genes of the ortho-cleavage pathway. The large number of mono- and dioxygenase genes in the genomes suggests that the two strains have a broader substrate range than known thus far. 相似文献
29.
Mitotic catastrophe is an oncosuppressive mechanism that senses mitotic failure leading to cell death or senescence. As such, it protects against aneuploidy and genetic instability, and its induction in cancer cells by exogenous agents is currently seen as a promising therapeutic end point. Apoptin, a small protein from Chicken Anemia Virus (CAV), is known for its ability to selectively induce cell death in human tumor cells. Here, we show that apoptin triggers p53-independent abnormal spindle formation in osteosarcoma cells. Approximately 50% of apoptin-positive cells displayed non-bipolar spindles, a 10-fold increase as compared to control cells. Besides, tumor cells expressing apoptin are greatly limited in their progress through anaphase and telophase, and a significant drop in mitotic cells past the meta-to-anaphase transition is observed. Time-lapse microscopy showed that mitotic osteosarcoma cells expressing apoptin displayed aberrant mitotic figures and/or had a prolonged cycling time during mitosis. Importantly, all dividing cells expressing apoptin eventually underwent cell death either during mitosis or during the following interphase. We infer that apoptin can efficiently trigger cell death in dividing human tumor cells through induction of mitotic catastrophe. However, the killing activity of apoptin is not only confined to dividing cells, as the CAV-derived protein is also able to trigger caspase-3 activation and apoptosis in non-mitotic cancer cells. 相似文献
30.
Farsani Seyed Mohammad Jazaeri Jebbink Maarten F Deijs Martin Canuti Marta van Dort Karel A Bakker Margreet Grady Bart PX Prins Maria van Hemert Formijn J Kootstra Neeltje A van der Hoek Lia 《Virology journal》2013,10(1):1-7