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《Cell reports》2020,30(1):153-163.e5
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Isolation and characterization of a type II restriction endonuclease from Streptococcus thermophilus
The alpha-toxin (phospholipase C) of Clostridium perfringens has been reported to contain catalytically essential zinc ions. We report here that histidine residues are essential for the co-ordination of these ion(s). Incubation of alpha toxin with diethylpyrocarbonate, a histidine modifying reagent, did not result in the loss of phospholipase C activity unless the protein was first incubated with EDTA, suggesting that zinc ions normally protect the susceptible histidine residues. When the amino acid sequences of three phospholipase C's were aligned, essential zinc binding histidine residues in the non-toxic B. cereus phospholipase C were found in similar positions in the toxic C. perfringens enzyme and the weakly toxic C. bifermentans phospholipase C. 相似文献
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The daily activity of the slug Arion lusitanicus was studied using time‐lapse video analysis in the laboratory. Under constant temperature (18°C) and 16–h photoperiod, the activity of slugs was measured in half‐hourly periods as locomotor activity, feeding or resting. Track lengths were determined using image analysis. Locomotion of A. lusitanicus was greatest at 5:30, 1.5 h after sunrise, and at 20:30, 1 h after sunset; least locomotor activity occurred between 13:00 and 14:00. The mean distance travelled by A. lusitanicus in 24 h was 10.8 m. The largest slug was the most active and the smallest the least. Slugs spent 68% of 24 hours resting, mainly under artificial shelter traps, 27% in locomotion and 4% feeding. Feeding occurred mainly during the hours of dakness (76%). All categories of behaviour investigated varied greatly between individuals and also between times of day. Homing to artificial shelters and other roost sites was regularly observed within 24 h (41%), but decreased considerably thereafter. The behavioural patterns proved to be in agreement with those found in a previous field investigation and are therefore also discussed with a view to their importance in pest control. 相似文献
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Helmut Tr?ster Wolfgang Kissel Michael F. Trendelenburg Ansgar Hofmann 《Molecular & general genetics : MGG》1989,217(2-3):533-535
Summary Eight representative recombinant background clones of λEMBL3 were analysed usingKpnI,BamHI,SalI,EcoRI andHindIII digestion. We found that λEMBL3 carries its own left arm in theBamHI cloning site. In this way, recombinant molecules were found to be generated which can grow onEscherichia coli strain NM539. In all cases analysed, the left arm DNA was inserted in a head to tail orientation. Seven clones carried a
restoredBamHI site at thecos site-BamHI site connection. In the region where the inserted left arm and the right arm were ligated,BamHI cloning produces a large palindromic sequence consisting of two polylinkers. ThisBamHI site was incompletely cleaved in all cases analysed. We assume that a part of the λ DNA molecule in this region shows a
cruciform structure prohibiting recognition or cleavage of this site by restriction endonucleaseBamHI. 相似文献
7.
Basidiomycetous fungi, two saprophytes and three mycorrhizal, were used to assess the specificity of DNA hybridization for
distinguishing genera from one another. Interspecific comparisons were done with several isolates of mycorrhizal fungi,Laccaria bicolor andL. laccata, collected from diverse geographical sites. The DNAs were digested with four restriction nucleases and separated by gel electrophoresis
into patterns of DNA fragments called restriction fragment length polymorphisms (RFLPs). The RFLPs were hybridized with a
radioactively-labeled DNA probe encoding Basidiomycetous ribosomal RNA genes. The five genera were discernable using both
unprobed and probed RFLPs. Hybridization of probe DNA with RFLPs was isolate-specific for all nine Laccaria isolates examined.
The reclassification of aL. bicolor isolate is supported, demonstrating that hybridization of RFLPs offers an additional tool for taxonomy of ectomycorrhizal
fungi. The method may have field application for distinguishing known isolates if their DNA fingerprints are previously ascertained
and are distinct from RFLPs of indigenous organisms. 相似文献
8.
Mitochondrial DNA polymorphism in native Philippine cattle based on restriction endonuclease cleavage patterns 总被引:4,自引:0,他引:4
Tomomasa Watanabe Joseph S. Masangkay Shigeharu Wakana Naruya Saitou Takeshi Tomita 《Biochemical genetics》1989,27(7-8):431-438
An analysis of patterns of cleavage of mtDNA by restriction endonucleases was performed for nine individuals from the Philippine
population of native cattle. MtDNA polymorphisms were detected in the restriction patterns generated by the following six
enzymes,BamHI,BglII,EcoRV,HindIII,PstI, andScaI. The restriction patterns showing polymorphisms were distributed nonrandomly among the nine individuals examined from the
Philippine population of native cattle, indicating the existence of two separate types of mtDNA. These two types of mtDNA
are very different from each other, at the level of subspecies. Since the native Philippine cattle are considered to represent
an admixture of European and Indian cattle, the two types of mtDNA must be derived from the mtDNAs of both varieties. The
polymorphic sites in mtDNA have been located on a restriction map, and the nucleotide substitutions at some of the sites have
also been estimated. 相似文献
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K Machaca M M Compton 《Biology of the cell / under the auspices of the European Cell Biology Organization》1992,76(1):15-22
In the current study the internucleosomal DNA cleavage activity associated with apoptosis was investigated in avian thymocytes. Thymocyte nuclear proteins from glucocorticoid-treated chickens were incubated with chicken red blood cell (cRBC) nuclei, and DNA degradation was analyzed by agarose gel electrophoresis and fluorescence-activated flow cytometry. The thymocyte nuclear extract contained an endonuclease activity that degraded cRBC chromatin at internucleosomal sites as detected by agarose gel electrophoresis. Flow cytometry analysis of cRBC nuclei that were treated with thymocyte nuclear proteins demonstrated a loss of cellular DNA as a function of the amount of added nuclease activity. Furthermore, it was demonstrated that the thymocyte nuclear extract contained a nuclease activity that was capable of degrading radiolabelled naked 32P-DNA into acid soluble DNA fragments. All three assay methods demonstrate that the thymocyte nuclease activity can be inhibited by EDTA, zinc ions and the nuclease inhibitor aurintricarboxylic acid. Based on the analysis of cofactor requirement of this nuclease activity and its susceptibility to inhibitors, the endonuclease activity present in avian apoptotic thymocytes appears to be identical to the mammalian counterpart. 相似文献