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21.
Accumulation of the proteolytic marker peptide ubiquitin in the trophoblast of mammalian blastocysts
Sutovsky P Motlik J Neuber E Pavlok A Schatten G Palecek J Hyttel P Adebayo OT Adwan K Alberio R Bagis H Bataineh Z Bjerregaard B Bodo S Bryja V Carrington M Couf M de la Fuente R Diblik J Esner M Forejt J Fulka J Geussova G Gjorret JO Libik M Hampl A Hassane MS Houshmand M Hozak P Jezova M Kania G Kanka J Kandil OM Kishimoto T Klima J Kohoutek J Kopska T Kubelka M Lapathitis G Laurincik J Lefevre B Mihalik J Novakova M Oko R Omelka R Owiny D Pachernik J Pacholikova J Peknicova J Pesty A 《Cloning and stem cells》2001,3(3):157-161
Ubiquitination is a universal protein degradation pathway in which the molecules of 8.5-kDa proteolytic peptide ubiquitin are covalently attached to the epsilon-amino group of the substrate's lysine residues. Little is known about the importance of this highly conserved mechanism for protein recycling in mammalian gametogenesis and fertilization. The data obtained by the students and faculty of the international training course Window to the Zygote 2000 demonstrate the accumulation of ubiquitin-cross-reactive structures in the trophoblast, but not in the inner cell mass of the expanding bovine and mouse blastocysts. This observation suggests that a major burst of ubiquitin-dependent proteolysis occurs in the trophoblast of mammalian peri-implantation embryos. This event may be important for the success of blastocyst hatching, differentiation of embryonic stem cells into soma and germ line, and/or implantation in both naturally conceived and reconstructed mammalian embryos. 相似文献
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G.M. Langdon M. Bruix A. Gálvez E. Valdivia M. Maqueda M. Rico 《Journal of biomolecular NMR》1998,12(1):173-175
The bacteriocin AS-48 is a cationic peptide (7149 Da) having a broad antimicrobial spectrum, encoded by the 68 kb conjugative plasmid pMB2 from Enterococcus faecalis S-48. It is a unique peptide since it has a cyclic structure, which is achieved by the formation of a tail–head peptide bond after ribosomal synthesis (Gálvez et al., 1989; Martínez-Bueno et al., 1994; Samyn et al., 1994). Preliminary CD and calorimetric studies (data not shown) pointed towards a highly helical and very stable three dimensional structure.All the information gathered until now indicates that the target of AS-48 is the cytoplasmic membrane in which it opens channels or pores, leading to dissipation of the proton motive force and cell death, which in some cases is also followed by bacterial lysis (Gálvez et al., 1991). This peptide is a suitable tool for studying protein–membrane interactions, and it also offers promising perspectives for biotechnological applications.Knowledge of the 3D structure of AS-48 is a first step in the conduct of further structure–function studies. Here we report the complete1 H NMR assignment of its proton resonances together with the resulting secondary structure pattern as prerequisites for the determination of a high-resolution 3D solution structure. 相似文献
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In the nurse plant syndrome, or nurse association, seedlings (beneficiaries) are associated with adult shrubs/trees (benefactors).
This phenomenon has been documented in several regions of the planet. Abiotic stress amelioration (one mechanism of facilitation)
is one of the causes of this association. Most of the studies addressing the nurse syndrome have been conducted on spatial
scales of a few hectares and have focused on only one or a few species. Moreover, there is an almost complete lack of studies
addressing the incidence and characteristics of the nurse phenomenon in the arid Andes of South America. We undertook a first
approximation to the study of facilitation in these ecosystems. The study was conducted at local and regional scales and involved
the assessment of the spatial distribution of juveniles (seedlings and saplings) of 51 populations of 16 shrub and 12 cactus
species in relation to shrub cover at 20 localities of the Prepuna (subtropical Andes of Bolivia and Argentina, 20–26°S).
In terms of spatial distribution, the juveniles of most of the populations of shrubs studied were distributed both under the
shrubs and in open spaces, thereby showing an apparent indifference to microhabitat. Globose and opuntioid cacti were preferentially
distributed below the canopies of shrubs and were usually more associated with the dominant shrub species, which stood out
as better potential nurses. The pattern was consistent throughout the region, including the more mesic and arid localities.
The fact that Prepuna woody species are capable of establishing in open spaces would confer this region a greater resilience.
Our findings further suggest that community dynamics in arid and semi-arid environments are more variable than previously
thought. 相似文献
27.
A protein discovered within inner mitochondrial membranes (IMM), designated as the mitochondrial ryanodine receptor (mRyR), has been recognized recently as a modulator of Ca2+ fluxes in mitochondria. The present study provides fundamental pharmacological and electrophysiological properties of this mRyR. Rat cardiac IMM fused to lipid bilayers revealed the presence of a mitochondrial channel with gating characteristics similar to those of classical sarcoplasmic reticulum RyR (SR-RyR), but a variety of other mitochondrial channels obstructed clean recordings. Mitochondrial vesicles were thus solubilized and subjected to sucrose sedimentation to obtain mRyR-enriched fractions. Reconstitution of sucrose-purified fractions into lipid bilayers yielded Cs+-conducting, Ca2+-sensitive, large conductance (500-800 pS) channels with signature properties of SR-RyRs. Cytosolic Ca2+ increased the bursting frequency and mean open time of the channel. Micromolar concentrations of ryanodine induced the appearance of subconductance states or inhibited channel activity altogether, while Imperatoxin A (IpTxa), a specific activator of RyRs, reversibly induced the appearance of distinct subconductance states. Remarkably, the cardiac mRyR displayed a Ca2+ dependence of [3H]ryanodine binding curve similar to skeletal RyR (RyR1), not cardiac RyR (RyR2). Overall, the mRyR displayed elemental attributes that are present in single channel lipid bilayer recordings of SR-RyRs, although some exquisite differences were also noted. These results therefore provide the first direct evidence that a unique RyR occurs in mitochondrial membranes. 相似文献
28.
Ricardo A. Scrosati Amanda S. Knox Nelson Valdivia Markus Molis 《Helgoland Marine Research》2011,65(2):91-102
Environmental stress affects species richness and diversity in communities, but the precise form of the relationship is unclear.
We tested an environmental stress model (ESM) that predicts a unimodal pattern for total richness and diversity in local communities
across the full stress gradient where a regional biota can occur. In 2008, we measured richness and diversity (considering
all macrobenthic species) across the entire intertidal range on three rocky shores on Helgoland Island, Germany. Intertidal
elevation is known to be positively related to abiotic stress. Since Helgoland is between the northern and southern biogeographic
boundaries for the cold-temperate NE Atlantic intertidal biota, it exhibits low stress levels for this biota at low elevations
and high stress at high elevations because of long (>6 h) emersion times. Thus, we predicted a unimodal trend for richness
and diversity across elevation. On all three shores, richness increased from high to middle elevations, but remained similar
between middle and low elevations. Diversity followed the same trend on one shore and different trends (although also non-unimodal)
on the other two. Evenness explained the trend differences between richness and diversity. Overall, our study yielded little
support for the ESM. Reasons for richness and diversity not decreasing at low elevations may be related to influences of mostly
subtidal species, Helgoland’s intertidal range, or sampling resolution. Our study also suggests that the ESM must be developed
further to differentiate between richness and diversity. We offer recommendations to improve future ESM research using intertidal
systems. 相似文献
29.
Molecular Ecology Resources Primer Development Consortium Austin JD Bertin A Bórquez JP Cárdenas L Cardoza TB Chapman F De Sousa AC De Souza AP Douglas KC Ellwood SR Ferriol M Garmendia A Gouin N Hargrove J Jasti M Keränen I Knott KE Konec M Kuitunen K Lima MP Linde CC Merle H Oliva ME Pérez M Saarinen E Samollow PB Scarpassa VM Segura I Smith L Trontelj P Valdivia IM Wallwork H Wellenreuther M 《Molecular ecology resources》2011,11(4):757-758
This article documents the addition of 111 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Acipenser oxyrinchus desotoi, Anopheles nuneztovari sensu lato, Asellus aquaticus, Calopteryx splendens, Calopteryx virgo, Centaurea aspera, Centaurea seridis, Chilina dombeyana, Proctoeces cf. lintoni and Pyrenophora teres f. teres. 相似文献
30.
R.?Fernández-Pacheco M.?R.?IbarraEmail author J.?G.?Valdivia C.?Marquina D.?Serrate M.?S.?Romero M.?Gutiérrez J.?Arbiol 《NanoBioTechnology》2005,1(3):300-303
Bioferrofluids obtained from carbon coated iron nanoparticles are promising candidates for magnetic drug delivery. The carbon
cages render the particles biocompatible, and provide a good support for drug adsorption. We propose a method in which gold
plated permanent magnets are implanted directly in the affected organ, close to the tumour, by endoscopic techniques. The
bioferrofluid charged with the chemotherapeutic agent is injected and the particles attracted to the magnet, then desorption
of the drug takes place at the tumoral region. This method seems to be more promising, costless and effective than that based
on the application of external magnetic fields. Preliminary results of drug adsorption and a preclinical experimental animal
model are described. 相似文献