全文获取类型
收费全文 | 111篇 |
免费 | 14篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 10篇 |
2014年 | 4篇 |
2013年 | 8篇 |
2012年 | 4篇 |
2011年 | 6篇 |
2010年 | 5篇 |
2009年 | 10篇 |
2008年 | 13篇 |
2007年 | 7篇 |
2006年 | 4篇 |
2005年 | 3篇 |
2004年 | 4篇 |
2003年 | 1篇 |
2002年 | 7篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1981年 | 1篇 |
1976年 | 2篇 |
排序方式: 共有125条查询结果,搜索用时 15 毫秒
1.
2.
Summary The Upper Santonian to Lower CampanianLacazina Limestone consists of massive, often amalgamated beds of packstones and grainstones which were deposited in a shallow marine
environment. The most abundant skeletal components are miliolid foraminifera, echinoderm, bivalve and bryozoan fragments,
peloids and sparse red algae. Small, solitary corals only occur sporadically. Hermatypic corals, sponges and green algae are
missing. The series which reaches thicknesses between 60 m and 160 m, was sampled at intervals of 0.5 m at five localities.
The petrographic features throughout the series are mainly a product of changing depositional energy. The limestones are well
cemented. Diagenesis is characterized by a transition from marine phreatic to burial cementation. Syntaxial and blocky calcite
cements predominate over early acicular to bladed and microgranular cements.
The faunal association within theLacazina Limestone exhibits features typical for temperate water i.e.foramol carbonates. On the other hand, oxygen (δ18O =-1.7 to −6.3 ‰ PDB) and carbon (δ13C to 3.0‰ PDB) isotope values of diagentically unaltered bivalve shells indicate warm surface waters corresponding better
to the palaeogeographical situation of theLacazina Limestone. Nutrient-surplus is proposed as a limiting factor preventing the development of reefs and finally ofchlorozoan sediments.
In the sense of sequence stratigraphy, theLacazina Limestone is interpreted to contain transgressive and highstand systems tracts. This interpretation fits well into theHaq-Vail-curve. The series shows no visible high-frequency cyclicity in the field. Several cycles were found by means of principle
component analysis and spectral analysis. Their relationships to the Milankovitch spectrum are discussed.
The ammonite fauna of the unit and of preceding sediments (late Coniacian to early Campanian) is described and some inoceramids
are figured. They permit—for the first time—the exact dating of theLacazina Limestone in the Basco-Cantabrian Basin (BCB) and throw light on a prominent faunal change at the Coniacian/Santonian boundary.
The Cenomanian to Coniacian ammonite faunas which were dominated by endemic Tethyan pseudoceratitic faunas are replaced by
cosmopolitan species dominated by Madagascan elements. This drastic change permits speculations about the installation of
a new oceanic current system in the Santonian. 相似文献
3.
Emma J. Gagen Harald Huber Travis Meador Kai-Uwe Hinrichs Michael Thomm 《Applied and environmental microbiology》2013,79(20):6400-6406
The uncultured miscellaneous crenarchaeotic group (MCG) archaea comprise one of the most abundant microbial groups in the Earth''s subsurface environment. However, very little information is available regarding the lifestyle, physiology, and factors controlling the distribution of members of this group. We established a novel method using both cultivation and molecular techniques, including a pre-PCR propidium monoazide treatment, to investigate viable members of the MCG in vitro. Enrichment cultures prepared from estuarine sediment were provided with one of a variety of carbon substrates or cultivation conditions and incubated for 3 weeks. Compared with the samples from time zero, there was an order-of-magnitude increase in the number of MCG 16S rRNA genes in almost all cultures, indicating that MCG archaea are amenable to in vitro cultivation. None of the tested substrates or conditions significantly stimulated growth of MCG archaea more than the basal medium alone; however, glycerol (0.02%) had a significantly inhibitory effect (P < 0.05). Diversity analysis of populations resulting from four culture treatments (basal medium, addition of amino acids, H2-CO2 as the gas phase, or initial aerobic conditions) revealed that the majority of viable MCG archaea were affiliated with the MCG-8 and MCG-4 clusters. There were no significant differences in MCG diversity between these treatments, also indicating that some members of MCG-4 and MCG-8 are tolerant of initially oxic conditions. The methods outlined here will be useful for further investigation of MCG archaea and comparison of substrates and cultivation conditions that influence their growth in vitro. 相似文献
4.
Nicole Sommer Tina Junne Kai-Uwe Kalies Martin Spiess Enno Hartmann 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》2013,1833(12):3104-3111
Membrane protein insertion and topogenesis generally occur at the Sec61 translocon in the endoplasmic reticulum membrane. During this process, membrane spanning segments may adopt two distinct orientations with either their N- or C-terminus translocated into the ER lumen. While different topogenic determinants in membrane proteins, such as flanking charges, polypeptide folding, and hydrophobicity, have been identified, it is not well understood how the translocon and/or associated components decode them. Here we present evidence that the translocon-associated protein (TRAP) complex is involved in membrane protein topogenesis in vivo. Small interfering RNA (siRNA)-mediated silencing of the TRAP complex in HeLa cells enhanced the topology effect of mutating the flanking charges of a signal-anchor, but not of increasing signal hydrophobicity. The results suggest a role of the TRAP complex in moderating the ‘positive-inside’ rule. 相似文献
5.
Oliver G. Bosch Michael Wagner Frank Jessen Kai-Uwe Kühn Alexius Joe Erich Seifritz Wolfgang Maier Hans-Jürgen Biersack Boris B. Quednow 《PloS one》2013,8(4)
Introduction
3,4-Methylenedioxymethamphetamine (MDMA, “ecstasy”) is a recreational club drug with supposed neurotoxic effects selectively on the serotonin system. MDMA users consistently exhibit memory dysfunction but there is an ongoing debate if these deficits are induced mainly by alterations in the prefrontal or mediotemporal cortex, especially the hippocampus. Thus, we investigated the relation of verbal memory deficits with alterations of regional cerebral brain glucose metabolism (rMRGlu) in recreational MDMA users.Methods
Brain glucose metabolism in rest was assessed using 2-deoxy-2-(18F)fluoro-D-glucose positron emission tomography (18FDG PET) in 19 male recreational users of MDMA and 19 male drug-naïve controls. 18FDG PET data were correlated with memory performance assessed with a German version of the Rey Auditory Verbal Learning Test.Results
As previously shown, MDMA users showed significant impairment in verbal declarative memory performance. PET scans revealed significantly decreased rMRGlu in the bilateral dorsolateral prefrontal and inferior parietal cortex, bilateral thalamus, right hippocampus, right precuneus, right cerebellum, and pons (at the level of raphe nuclei) of MDMA users. Among MDMA users, learning and recall were positively correlated with rMRGlu predominantly in bilateral frontal and parietal brain regions, while recognition was additionally related to rMRGlu in the right mediotemporal and bihemispheric lateral temporal cortex. Moreover, cumulative lifetime dose of MDMA was negatively correlated with rMRGlu in the left dorsolateral and bilateral orbital and medial PFC, left inferior parietal and right lateral temporal cortex.Conclusions
Verbal learning and recall deficits of recreational MDMA users are correlated with glucose hypometabolism in prefrontal and parietal cortex, while word recognition was additionally correlated with mediotemporal hypometabolism. We conclude that memory deficits of MDMA users arise from combined fronto-parieto-mediotemporal dysfunction. 相似文献6.
7.
Yurong Cheng Yong Li Nora Scherer Franziska Grundner-Culemann Terho Lehtimki Binisha H. Mishra Olli T. Raitakari Matthias Nauck Kai-Uwe Eckardt Peggy Sekula Ulla T. Schultheiss 《PLoS genetics》2022,18(4)
Osteopontin (OPN), encoded by SPP1, is a phosphorylated glycoprotein predominantly synthesized in kidney tissue. Increased OPN mRNA and protein expression correlates with proteinuria, reduced creatinine clearance, and kidney fibrosis in animal models of kidney disease. But its genetic underpinnings are incompletely understood. We therefore conducted a genome-wide association study (GWAS) of OPN in a European chronic kidney disease (CKD) population. Using data from participants of the German Chronic Kidney Disease (GCKD) study (N = 4,897), a GWAS (minor allele frequency [MAF]≥1%) and aggregated variant testing (AVT, MAF<1%) of ELISA-quantified serum OPN, adjusted for age, sex, estimated glomerular filtration rate (eGFR), and urinary albumin-to-creatinine ratio (UACR) was conducted. In the project, GCKD participants had a mean age of 60 years (SD 12), median eGFR of 46 mL/min/1.73m2 (p25: 37, p75: 57) and median UACR of 50 mg/g (p25: 9, p75: 383). GWAS revealed 3 loci (p<5.0E-08), two of which replicated in the population-based Young Finns Study (YFS) cohort (p<1.67E-03): rs10011284, upstream of SPP1 encoding the OPN protein and related to OPN production, and rs4253311, mapping into KLKB1 encoding prekallikrein (PK), which is processed to kallikrein (KAL) implicated through the kinin-kallikrein system (KKS) in blood pressure control, inflammation, blood coagulation, cancer, and cardiovascular disease. The SPP1 gene was also identified by AVT (p = 2.5E-8), comprising 7 splice-site and missense variants. Among others, downstream analyses revealed colocalization of the OPN association signal at SPP1 with expression in pancreas tissue, and at KLKB1 with various plasma proteins in trans, and with phenotypes (bone disorder, deep venous thrombosis) in human tissue. In summary, this GWAS of OPN levels revealed two replicated associations. The KLKB1 locus connects the function of OPN with PK, suggestive of possible further post-translation processing of OPN. Further studies are needed to elucidate the complex role of OPN within human (patho)physiology. 相似文献
8.
9.
As a step towards developing a biosensor which can detect airborne protease droplets, a biosensor which had previously been developed to detect protease in solution is shown to be capable of detecting different concentrations of protease in liquid films on the sensor surface in air. The biosensor measured impedance change due to proteolytic digestion of its gelatin coating. In saturated air there was a rise in impedance, with a loss in weight of the gelatin, in proportion to collagenase concentration. The addition of glycerol to the gelatin caused a lower impedance response and smaller loss in weight. A critical thickness of the gelatin layer prior to a more rapid change in the rate of impedance was noted, with and without the addition of glycerol. In low air humidity (40%), with gelatin, all collagenase concentrations produced a very similar rapid increase in impedance. However, with glycerol-enhanced gelatin, there was a clear distinction between the extent of impedance change with different collagenase concentrations. The application of these findings for use in the field of bioaerosol sampling is discussed. 相似文献
10.
Phylogenetic and Metabolic Diversity of Planctomycetes from Anaerobic, Sulfide- and Sulfur-Rich Zodletone Spring, Oklahoma 下载免费PDF全文
Mostafa S. Elshahed Noha H. Youssef Qingwei Luo Fares Z. Najar Bruce A. Roe Tracy M. Sisk Solveig I. Bühring Kai-Uwe Hinrichs Lee R. Krumholz 《Applied microbiology》2007,73(15):4707-4716
We investigated the phylogenetic diversity and metabolic capabilities of members of the phylum Planctomycetes in the anaerobic, sulfide-saturated sediments of a mesophilic spring (Zodletone Spring) in southwestern Oklahoma. Culture-independent analyses of 16S rRNA gene sequences generated using Planctomycetes-biased primer pairs suggested that an extremely diverse community of Planctomycetes is present at the spring. Although sequences that are phylogenetically affiliated with cultured heterotrophic Planctomycetes were identified, the majority of the sequences belonged to several globally distributed, as-yet-uncultured Planctomycetes lineages. Using complex organic media (aqueous extracts of the spring sediments and rumen fluid), we isolated two novel strains that belonged to the Pirellula-Rhodopirellula-Blastopirellula clade within the Planctomycetes. The two strains had identical 16S rRNA gene sequences, and their closest relatives were isolates from Kiel Fjord (Germany), Keauhou Beach (HI), a marine aquarium, and tissues of marine organisms (Aplysina sp. sponges and postlarvae of the giant tiger prawn Penaeus monodon). The closest recognized cultured relative of strain Zi62 was Blastopirellula marina (93.9% sequence similarity). Detailed characterization of strain Zi62 revealed its ability to reduce elemental sulfur to sulfide under anaerobic conditions, as well as its ability to produce acids from sugars; both characteristics may potentially allow strain Zi62 to survive and grow in the anaerobic, sulfide- and sulfur-rich environment at the spring source. Overall, this work indicates that anaerobic metabolic abilities are widely distributed among all major Planctomycetes lineages and suggests carbohydrate fermentation and sulfur reduction as possible mechanisms employed by heterotrophic Planctomycetes for growth and survival under anaerobic conditions. 相似文献