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131.
The concept of ecosystem services (ESs) is a relatively new scientific methodology, offering a possible approach to the prevention of ecological problems caused by human action and to the resolution of conflicts arising from land-use questions. Since ESs were launched as a major conceptual tool in the Millennium Ecosystem Assessment (MA, 2005), interest in them has been increasing. Despite the scientific as well as economic and political enthusiasm for the ES approach, only few case studies have as yet been published. We studied the interface between ESs and landscape planning in Forest Lapland, in northern Finland. In the article, we present a methodology and various databases which can be used in applied research on ESs. We classify the ESs offered by various biotopes of the study area, and examine the effects of different land-use forms on the provision of ESs. On the basis of our results, we suggest possible uses of the European CORINE land cover database in case studies.  相似文献   
132.
Many successful invasions have taken place in systems where harmful disturbance has changed habitat conditions. However, less attention has been paid to the role of habitat restoration, which modifies habitats and thus also has the potential to facilitate invasions. We examined whether in‐stream habitat restorations have the potential to either facilitate or resist invasion by two widely introduced non‐native stream salmonids, Salvelinus fontinalis Mitchill and Oncorhynchus mykiss Walbaum, in Finland. A physical habitat simulation system was used to calculate whether the habitat area for the target species increased or decreased following the restorations. For comparison, we also reported results for four native stream fish species. The simulations showed that the restored streams provided the highest amount of usable habitat area for the native species, particularly for Salmo salar L. and Gottus gobio L. However, it was interesting to note that the restorations significantly increased habitat quality for the two non‐native species, especially at low flows. Nevertheless, the non‐native species had the lowest amount of usable habitat area overall. The modeling results indicated that not only habitat destruction but also habitat restoration could contribute to the spread of non‐native species. Fisheries and wildlife managers should be aware of the possibility, when restoring habitats in order to preserve native ecosystems, that non‐native species could manage to gain a foothold in restored habitats and use them as population sources for further spread. Knowing the widespread negative effect of non‐native species, this risk should not be underestimated.  相似文献   
133.
Soil fungal communities underneath willow canopies that had established on the forefront of a receding glacier were analyzed by cloning the polymerase chain reaction (PCR)-amplified partial small subunit (18S) of the ribosomal (rRNA) genes. Congruence between two sets of fungus-specific primers targeting the same gene region was analyzed by comparisons of inferred neighbor-joining topologies. The importance of chimeric sequences was evaluated by Chimera Check (Ribosomal Database Project) and by data reanalyses after omission of potentially chimeric regions at the 5'- and 3'-ends of the cloned amplicons. Diverse communities of fungi representing Ascomycota, Basidiomycota, Chytridiomycota, and Zygomycota were detected. Ectomycorrhizal fungi comprised a major component in the early plant communities in primary successional ecosystems, as both primer sets frequently detected basidiomycetes (Russulaceae and Thelephoraceae) forming mycorrhizal symbioses. Various ascomycetes (Ophiostomatales, Pezizales, and Sordariales) of uncertain function dominated the clone libraries amplified from the willow canopy soil with one set of primers, whereas the clone libraries of the amplicons generated with the second primer set were dominated by basidiomycetes. Accordingly, primer bias is an important factor in fungal community analyses using DNA extracted from environmental samples. A large proportion (>30%) of the cloned sequences were concluded to be chimeric based on their changing positions in inferred phylogenies after omission of possibly chimeric data. Many chimeric sequences were positioned basal to existing classes of fungi, suggesting that PCR artifacts may cause frequent discovery of new, higher level taxa (order, class) in direct PCR analyses. Longer extension times during the PCR amplification and a smaller number of PCR cycles are necessary precautions to allow collection of reliable environmental sequence data.  相似文献   
134.
Hyperforin and adhyperforin contribute to the antidepressant effects of Hypericum perforatum. The involvement of branched-chain amino acids in the biosynthesis of hyperforin and adhyperforin was demonstrated in H. perforatum shoot cultures. L-[U-(13)C(5)]Valine and L-[U-(13)C(6)]isoleucine, upon administration to the shoot cultures, were incorporated into acyl side chain of hyperforin and adhyperforin, respectively. Feeding the shoot cultures with unlabelled L-isoleucine at a concentration of 2mM induced a 3.7-fold increase in the production of adhyperforin. The addition of 3mM L-threonine, a precursor of isoleucine, stimulated a 2.0-fold increase in the accumulation of adhyperforin. The administration of L-valine at concentrations of 0-5mM had no stimulating effect on the hyperforin production in H. perforatum shoot cultures.  相似文献   
135.
Gammaherpesviruses are important pathogens whose lifelong survival in the host depends critically on their capacity to establish and reactivate from latency, processes regulated by both viral genes and the host immune response. Previous work has demonstrated that gamma interferon (IFN-gamma) is a key regulator of chronic infection with murine gammaherpesvirus 68 (gammaHV68), a virus that establishes latent infection in B lymphocytes, macrophages, and dendritic cells. In mice deficient in IFN-gamma or the IFN-gamma receptor, gammaHV68 gene expression is altered during chronic infection, and peritoneal cells explanted from these mice reactivate more efficiently ex vivo than cells derived from wild-type mice. Furthermore, treatment with IFN-gamma inhibits reactivation of gammaHV68 from latently infected wild-type peritoneal cells, and depletion of IFN-gamma from wild-type mice increases the efficiency of reactivation of explanted peritoneal cells. These profound effects of IFN-gamma on chronic gammaHV68 latency and reactivation raise the question of which cells respond to IFN-gamma to control chronic gammaHV68 infection. Here, we show that IFN-gamma inhibited reactivation of peritoneal cells and spleen cells harvested from mice lacking B lymphocytes, but not wild-type spleen cells, suggesting that IFN-gamma may inhibit reactivation in a cell type-specific manner. To directly test this hypothesis, we expressed the diphtheria toxin receptor specifically on either B lymphocytes or macrophages and used diphtheria toxin treatment to deplete these specific cells in vivo and in vitro after establishing latency. We demonstrate that macrophages, but not B cells, are responsive to IFN-gamma-mediated suppression of gammaHV68 reactivation. These data indicate that the regulation of gammaherpesvirus latency by IFN-gamma is cell type specific and raise the possibility that cell type-specific immune deficiency may alter latency in distinct and important ways.  相似文献   
136.
N-glycolyl GM1 ganglioside as a receptor for simian virus 40   总被引:1,自引:0,他引:1       下载免费PDF全文
Carbohydrate microarrays have emerged as powerful tools in analyses of microbe-host interactions. Using a microarray with 190 sequence-defined oligosaccharides in the form of natural glycolipids and neoglycolipids representative of diverse mammalian glycans, we examined interactions of simian virus 40 (SV40) with potential carbohydrate receptors. While the results confirmed the high specificity of SV40 for the ganglioside GM1, they also revealed that N-glycolyl GM1 ganglioside [GM1(Gc)], which is characteristic of simian species and many other nonhuman mammals, is a better ligand than the N-acetyl analog [GM1(Ac)] found in mammals, including humans. After supplementing glycolipid-deficient GM95 cells with GM1(Ac) and GM1(Gc) gangliosides and the corresponding neoglycolipids with phosphatidylethanolamine lipid groups, it was found that GM1(Gc) analogs conferred better virus binding and infectivity. Moreover, we visualized the interaction of NeuGc with VP1 protein of SV40 by molecular modeling and identified a conformation for GM1(Gc) ganglioside in complex with the virus VP1 pentamer that is compatible with its presentation as a membrane receptor. Our results open the way not only to detailed studies of SV40 infection in relation to receptor expression in host cells but also to the monitoring of changes that may occur with time in receptor usage by the virus.  相似文献   
137.
138.
Streptococci have been considered to lack the classical SOS response, defined by increased mutation after UV exposure and regulation by LexA. Here we report the identification of a potential self-regulated SOS mutagenesis gene cassette in the Streptococcaceae family. Exposure to UV light was found to increase mutations to antibiotic resistance in Streptococcus uberis cultures. The mutational spectra revealed mainly G:C-->A:T transitions, and Northern analyses demonstrated increased expression of a Y-family DNA polymerase resembling UmuC under DNA-damaging conditions. In the absence of the Y-family polymerase, S. uberis cells were sensitive to UV light and to mitomycin C. Furthermore, the UV-induced mutagenesis was almost completely abolished in cells deficient in the Y-family polymerase. The gene encoding the Y-family polymerase was localized in a four-gene operon including two hypothetical genes and a gene encoding a HdiR homolog. Electrophoretic mobility shift assays demonstrated that S. uberis HdiR binds specifically to an inverted repeat sequence in the promoter region of the four-gene operon. Database searches revealed conservation of the gene cassette in several Streptococcus species, including at least one genome each of Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus mitis, Streptococcus sanguinis, and Streptococcus thermophilus strains. In addition, the umuC operon was localized in several mobile DNA elements of Streptococcus and Lactococcus species. We conclude that the hdiR-umuC-ORF3-ORF4 operon represents a novel gene cassette capable of mediating SOS mutagenesis among members of the Streptococcaceae.  相似文献   
139.
In Finland (population 5 million) the organised Pap screening programme for preventing cervical cancer has been in action already for 45 years. Women aged 30 to 64 are targeted (N 1.25 million) and the screening interval is five years. The programme invites women seven times in a lifetime; the attendance rate per one screening invitational round is 73%. The programme has affected markedly the cervical cancer rates in our country. During the decennia of its action there has been about 80% decrease in the age-adjusted cervical cancer incidence and mortality rates. The current age-standardised incidence rate is 4 and mortality rate 1 per 100,000 woman-years. In the current article we describe the organisational aspects of the programme; and pay attention to renovation of the programme taken place during the last decade when novel technological alternatives have been started to be used as the screening tests. By expanding the coverage and compliance of screening we still expect to increase the impact of the programme. Same time, efforts are needed to avoid overuse of services due to spontaneous screening, in order to decrease potential adverse effects and improve overall cost-effectiveness. A large-scale public health policy trial on Human papillomavirus (HPV) screening is on-going. Cross-sectional information available thus far suggests promising results. Follow-up of cancer rates after screening episodes are still required to evaluate optimal screening policies (e.g., screening intervals by age groups, and starting and stopping ages). We propose speeding up the use of modern technological alternatives in organised screening programmes.  相似文献   
140.
Improved ways to cleave peptide chains at engineered sites easily and specifically would form useful tools for biochemical research. Uses of such methods include the activation or inactivation of enzymes or the removal of tags for enhancement of recombinant protein expression or tags used for purification of recombinant proteins. In this work we show by gel electrophoresis and mass spectroscopy that salts of Co(II) and Cu(II) can be used to cleave fusion proteins specifically at sites where sequences of His residues have been introduced by protein engineering. The His residues could be either consecutive or spaced with other amino acids in between. The cleavage reaction required the presence of low concentrations of ascorbate and in the case of Cu(II) also hydrogen peroxide. The amount of metal ions required for cleavage was very low; in the case of Cu(II) only one to two molar equivalents of Cu(II) to protein was required. In the case of Co(II), 10 molar equivalents gave optimal cleavage. The reaction occurred within minutes, at a wide pH range, and efficiently at temperatures ranging from 0 degrees C to 70 degrees C. The work described here can also have implications for understanding protein stability in vitro and in vivo.  相似文献   
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