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41.
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Identifying and quantifying crop stressors interactions in agroecosystems is necessary to guide sustainable crop management strategies. Over the last 50 years, faba bean cropping area has been declining, partly due to yield instabilities associated with uneven insect pollination and herbivory. Yet, the effect of interactions between pollinators and a key pest, the broad bean beetle Bruchus rufimanus (florivorous and seed predating herbivore) on faba bean yield has not been investigated. Using a factorial cage experiment in the field, we investigated how interactions between two hypothesized stressors, lack of insect pollination by bumblebees and herbivory by the broad bean beetle, affect faba bean yield. Lack of bumblebee pollination reduced bean weight per plant by 15%. Effects of the broad bean beetle differed between the individual plant and the plant‐stand level (i.e., when averaging individual plant level responses at the cage level), likely due to high variation in the level of herbivory among individual plants. At the individual plant level, herbivory increased several yield components but only in the absence of pollinators, possibly due to plant overcompensation and/or pollination by the broad bean beetle. At the plant‐stand level, we found no effect of the broad bean beetle on yield. However, there was a tendency for heavier individual bean weight with bumblebee pollination, but only in the absence of broad bean beetle herbivory, possibly due to a negative effect of the broad bean beetle on the proportion of legitimate flower visits by bumblebees. This is the first experimental evidence of interactive effects between bumblebees and the broad bean beetle on faba bean yield. Our preliminary findings of negative and indirect associations between the broad bean beetle and individual bean weight call for a better acknowledgment of these interactions in the field in order to understand drivers of crop yield variability in faba bean.  相似文献   
43.
The vascular endothelial growth factors VEGFA and VEGFC are crucial regulators of vascular development. They exert their effects by dimerization and activation of the cognate receptors VEGFR2 and VEGFR3. Here, we have used in situ proximity ligation to detect receptor complexes in intact endothelial cells. We show that both VEGFA and VEGFC potently induce formation of VEGFR2/‐3 heterodimers. Receptor heterodimers were found in both developing blood vessels and immature lymphatic structures in embryoid bodies. We present evidence that heterodimers frequently localize to tip cell filopodia. Interestingly, in the presence of VEGFC, heterodimers were enriched in the leading tip cells as compared with trailing stalk cells of growing sprouts. Neutralization of VEGFR3 to prevent heterodimer formation in response to VEGFA decreased the extent of angiogenic sprouting. We conclude that VEGFR2/‐3 heterodimers on angiogenic sprouts induced by VEGFA or VEGFC may serve to positively regulate angiogenic sprouting.  相似文献   
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Procedures and reagents are needed to specifically detect all the macromolecules that are being identified in the course of genome projects. We discuss how this challenge may be met using a set of ligation-based reagents termed padlock probes and proximity ligation probes. These probes include elements with affinity for specific nucleic acid and protein molecules, respectively, along with unique identifier DNA sequence elements that encode the identity of the recognized target molecules. The information content of DNA strands that form in the detection reactions are recorded after amplification, allowing the recognized target molecules to be identified. The procedures permit highly specific solution-phase or localized analyses of large sets of target molecules as required in future molecular analyses.  相似文献   
46.
Synthesis of a novel series of structurally related pyrazoloquinoline nucleosides is described. All the newly synthesized compounds were examined for their in vitro antiviral activity against herpes simplex type-1 as shown by two different bioassays, namely; crystal violet staining or the MTS tetrazolium dye measurement. The acute toxicity (LD50) values of the biologically active compounds were determined.  相似文献   
47.
To study the effect of extracellular acidosis on apoptosis and necrosis during ischemia and reoxygenation, we exposed human post-mitotic NT2-N neurones to oxygen and glucose deprivation (OGD) followed by reoxygenation. In some experiments, pH of the cell medium was lowered to 5.9 during either OGD or reoxygenation or both. Staurosporine, used as a positive control for apoptosis, caused Poly(ADP-ribose)-polymerase (PARP) cleavage and nuclear fragmentation, but no PARP cleavage and little fragmentation were seen after OGD. Low molecular weight DNA fragments were found after staurosporine treatment, but not after OGD. No protective effect of caspase inhibitors was seen after 3 h of OGD and 21 h of reoxygenation, but after 45 h of reoxygenation caspase inhibition induced a modest improvement in 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide (MTT) cleavage. While acidosis during OGD accompanied by neutral medium during reoxygenation protected the neurones (MTT: 228 +/- 117% of neutral medium, p < 0.001), acidosis during reoxygenation only was detrimental (MTT: 38 +/- 25%, p < 0.01). We conclude that apoptotic mechanisms play a minor role after OGD in NT2-N neurones. The effect of acidosis on neuronal survival depends on the timing of acidosis, as acidosis was protective during OGD and detrimental during reoxygenation.  相似文献   
48.
Ten of the 11 known human siglecs or their murine orthologs have been evaluated for their specificity for over 25 synthetic sialosides representing most of the major sequences terminating carbohydrate groups of glycoproteins and glycolipids. Analysis has been performed using a novel multivalent platform comprising biotinylated sialosides bound to a streptavidin-alkaline phosphatase conjugate. Each siglec was found to have a unique specificity for binding 16 different sialoside-streptavidin-alkaline phosphatase probes. The relative affinities of monovalent sialosides were assessed for each siglec in competitive inhibition studies. The quantitative data obtained allows a detailed analysis of each siglec for the relative importance of sialic acid and the penultimate oligosaccharide sequence on binding affinity and specificity. Most remarkable was the finding that myelin-associated glycoprotein (Siglec-4) binds with 500-10,000-fold higher affinity to a series of mono- and di-sialylated derivatives of the O-linked T-antigen (Galbeta(1-3)-GalNAc(alpha)OThr) as compared with alpha-methyl-NeuAc.  相似文献   
49.
Antisense DNA target sites can be selected by the accessibility of the mRNA target. It remains unknown whether a mRNA site that is accessible to an antisense DNA is also a good candidate target site for a siRNA. Here, we reported a parallel analysis of 12 pairs of antisense DNAs and siRNA duplexes for their potency to inhibit reporter luciferase activity in mammalian cells, both of the antisense DNA and siRNA agents in a pair being directed to same site in the mRNA. Five siRNAs and two antisense DNAs turned out to be effective, but the sites targeted by those effective siRNAs and antisense DNAs did not overlap. Our results indicated that effective antisense DNAs and siRNAs have different preferences for target sites in the mRNA.  相似文献   
50.
Primary microcephaly has been mapped to five loci on different chromosomes. We present here the fine mapping of one of the loci, MCPH5, to a region of only 0.58 Mb located at the 1q31.3-1q32.1 junction. A genome scan was performed on five families from the Netherlands and Jordania, with 14 patients affected by microcephaly. A maximum LOD score of 4.78 was found for marker D1S1660 at the MCPH5 locus. Haplotype analysis suggests that the gene causing microcephaly is located between markers D1S3469 and D1S1660, which excludes the previously reported ASPM gene.  相似文献   
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