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991.
The metabolism of testosterone and dihydrotestosterone was studied in slices and cell fractions of mouse kidney. When testosterone was used as substrate, very little metabolism to dihydrotestosterone occurred suggesting very low 5α-reductase activity. When dihydrotestosterone was substrate, it was rapidly converted to 5α-androstane-3α, 17β-diol by a potent 3-keto-reductase. Ninety-five percent of this latter enzyme is located in cytosol and it requires NADPH as cofactor. The 3-keto-reductase may exist in two molecular forms which can be separated by polyacrylamide gel electrophoresis. Form A and B have mean molecular radii which correspond to molecular weights of 38, 700 and 28, 700, respectively. Sufficient 3-keto-reductase activity is present in cytosol at 0°C to reduce physiological concentrations (2×10?9 M) of dihydrotestosterone without the addition of cofactor. 3-Keto-reductase activity is higher in intact male than in castrate male or female mice and increases with androgen treatment.From these studies we conclude: (a) The virtual absence of 5α-reductase in mouse kidney is consistent with the thesis that testosterone rather than dihydrotestosterone may be the intracellular androgen in this organ. (b) Kinetic studies which depend upon the uptake and retention of dihydrotestosterone by receptor proteins may be difficult to interpret due to rapid metabolism of ligand. 相似文献
992.
Irene Bartolozzi Tiberio Daddi Carlo Punta Andrea Fiorati Fabio Iraldo 《Journal of Industrial Ecology》2020,24(1):101-115
The use of nanostructured materials has been recently proposed in the field of environmental nanoremediation. This approach consists in using nanomaterials not directly, but as building blocks for the design of nano‐porous micro‐dimensional systems, overcoming the eco‐ and health‐toxicology risks generally associated with the use of nano‐sized technologies. Herein we report the use of life cycle assessment (LCA) as an eco‐design tool for optimizing the production of cellulose nanosponges (CNS), nanostructured materials recently developed for water remediation purposes. LCA was applied from the acquisition of raw materials to the synthesis of CNS (from cradle‐to‐gate), considering three production systems, from the lab‐level to a modeled scale‐up system. The lab‐scale LCA identified the main environmental hotspots, namely the energy‐consuming steps and the final purification of the material (washing step). In a second lab‐scale production, an improvement action could be implemented, switching the washing solvent from methanol to water and decreasing the washing temperature. A second LCA showed a reduced contribution to the impacts from the materials, while the global impacts remained within the same order of magnitude. A simulated scale‐up of the process allowed to optimize the energy‐consuming steps and the water consumption, through internal recycling. A third LCA assessed the resulting benefits and a decrease in the global impacts by two orders of magnitude. Our study contributes to the discussion of LCA community, providing a focus on the importance of scaling‐up of emerging technologies, namely nanostructured porous materials, highlighting the benefits of a LCA based approach since the very beginning of product design (eco‐design). 相似文献
993.
Background and Purpose
The impact of traumatic brain injury (TBI) on the pathogenesis of Alzheimer disease (AD) is still controversial. The aim of our retrospective autopsy study was to assess the impact of TBE and ApoE allele frequency on the development of AD. 相似文献994.
Katja M. Kanninen Alexandra Grubman Jodi Meyerowitz Clare Duncan Jiang-Li Tan Sarah J. Parker Peter J. Crouch Brett M. Paterson James L. Hickey Paul S. Donnelly Irene Volitakis Imke Tammen David N. Palmer Anthony R. White 《PloS one》2013,8(3)
Mutations in the CLN6 gene cause a variant late infantile form of neuronal ceroid lipofuscinosis (NCL; Batten disease). CLN6 loss leads to disease clinically characterized by vision impairment, motor and cognitive dysfunction, and seizures. Accumulating evidence suggests that alterations in metal homeostasis and cellular signaling pathways are implicated in several neurodegenerative and developmental disorders, yet little is known about their role in the NCLs. To explore the disease mechanisms of CLN6 NCL, metal concentrations and expression of proteins implicated in cellular signaling pathways were assessed in brain tissue from South Hampshire and Merino CLN6 sheep. Analyses revealed increased zinc and manganese concentrations in affected sheep brain in those regions where neuroinflammation and neurodegeneration first occur. Synaptic proteins, the metal-binding protein metallothionein, and the Akt/GSK3 and ERK/MAPK cellular signaling pathways were also altered. These results demonstrate that altered metal concentrations, synaptic protein changes, and aberrant modulation of cellular signaling pathways are characteristic features in the CLN6 ovine form of NCL. 相似文献
995.
Michael W. Hess Irene Mittermann Christian Luschnig Rudolf Valenta 《Histochemistry and cell biology》1995,104(6):443-451
Actin was demonstrated for the first time at the EM level in the generative cell of mature angiosperm pollen by using immuno-gold labelling of high-pressure frozen and freeze-substitutedLedebouria socialis Roth anthers. In addition, profilin, an actin-monomer binding protein, is shown to coexist in the generative cell. We attribute the detection of actin and profilin to the applied cryomethods which yield a much better preservation of ultrastructure and antigenicity of delicate cytoskeletal constituents than conventional fixation techniques. Actin labelling was observed within the cytoplasm of the generative cell and became especially clear in close vicinity to microtubular bundles. Filamentous structures congruent with the actin labelling patterns do occur, but are not a frequent feature. Profilin was localised throughout the cytoplasm.Abbreviations Ac Acetone
BSA
bovine serum albumin
-
CFS
calf fetal serum
-
CGA
chicken gizzard actin
-
EA
Epon-Araldite
-
E-PTA
ethanolic phosphotungstic acid
-
FG
fish gelatine
-
GC
generative cell
-
LR
LR white
-
mAb
monoclonal antibody
-
Os
osmium tetroxide
-
Pb
lead-staining
-
PBS
phosphate-buffered saline
-
UA
uranyl acetate 相似文献
996.
997.
998.
Matteo Ramazzotti Irene Stefanini Monica Di Paola Carlotta De Filippo Lisa Rizzetto Luisa Berná Leonardo Dapporto Damariz Rivero Noemi Tocci Tobias Weil Marcello S. Lenucci Paolo Lionetti Duccio Cavalieri 《Environmental microbiology》2019,21(1):50-71
The quest to discover the variety of ecological niches inhabited by Saccharomyces cerevisiae has led to research in areas as diverse as wineries, oak trees and insect guts. The discovery of fungal communities in the human gastrointestinal tract suggested the host's gut as a potential reservoir for yeast adaptation. Here, we report the existence of yeast populations associated with the human gut (HG) that differ from those isolated from other human body sites. Phylogenetic analysis on 12 microsatellite loci and 1715 combined CDSs from whole-genome sequencing revealed three subclusters of HG strains with further evidence of clonal colonization within the host's gut. The presence of such subclusters was supported by other genomic features, such as copy number variation, absence/introgressions of CDSs and relative polymorphism frequency. Functional analysis of CDSs specific of the different subclusters suggested possible alterations in cell wall composition and sporulation features. The phenotypic analysis combined with immunological profiling of these strains further showed that sporulation was related with strain-specific genomic characteristics in the immune recognition pattern. We conclude that both genetic and environmental factors involved in cell wall remodelling and sporulation are the main drivers of adaptation in S. cerevisiae populations in the human gut. 相似文献
999.
Gene transfer, expression and inheritance of pRSV-rainbow trout-GH cDNA in the common carp, Cyprinus carpio (Linnaeus) 总被引:3,自引:0,他引:3
Peijung Zhang Mohammad Hayat Christopher Joyce Lucia Irene Gonzalez-Villaseor C. M. Lin Rex A. Dunham Thomas T. Chen Dennis A. Powers 《Molecular reproduction and development》1990,25(1):3-13
A recombinant plasmid containing the Rous sarcoma virus-long terminal repeat (RSV-LTR) promoter linked to rainbow trout (Salmo gairdneri) growth hormone (GH) cDNA was microinjected into fertilized carp eggs. Genomic DNA extracted from pectoral fin of individual presumptive transgenic fish was analyzed by dot blot and Southern blot hybridization, using the RSV-LTR and/or the GH cDNA sequences as probes. Out of 365 presumptive transgenic fish analyzed, 20 individuals were found to contain pRSV-rtGH-cDNA sequence in the genomic DNA. Expression of the trout GH polypeptide was detected by immunobinding assay in the red blood cells of nine transgenic fish tested. The level of expression, however, varied among the transgenics and could not be correlated with exogenous DNA copy number. Although there was considerable variation in the sizes of the transgenic fish, those microinjected during the one-cell stage were (P less than 0.05) 22% larger, on the average, than their sibling controls. A randomly selected fraction of the progeny derived from crosses between transgenic males and non-transgenic females inherited the foreign DNA. These transgenic progeny grew faster (P less than 0.05) than their non-transgenic siblings. 相似文献
1000.
Marke E. Swanson Thomas E. Hughes Irene St Denny Dennis S. France James R. Paterniti Jr Carlo Tapparelli Patrick Gfeller Kurt Bürki 《Transgenic research》1992,1(3):142-147
To examine the consequences of increased apolipoprotein A-I production on cholesterol and lipoprotein metabolism, we have
produced two lines of transgenic rats; one expressing moderate and one very high levels of human apolipoprotein A-I. The rats
were produced by microinjection of a 13 kbp DNA fragment containing the human apolipoprotein A-I gene plus 10 kbp of its 5′
flanking sequence and 1 kbp of its 3′ flanking sequence. Both lines of transgenic rats express human apolipoprotein A-I mRNA
in liver and human apolipoprotein A-I in plasma. Sera from these rats contain significantly higher levels of total apolipoprotein
A-I, high density lipoprotein cholesterol and phospholipid than sera from non-transgenic littermates. Transgenic rats expressing
high levels of human apolipoprotein A-I have reduced levels of serum rat apolipoprotein A-I suggesting a mechanism exists
to down-regulate apolipoprotein A-I production. These transgenic rats provide a unique animal model to examine the effects
of increased apolipoprotein A-I production on lipid and lipoprotein metabolism. 相似文献