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W. J. T. Kimber 《BMJ (Clinical research ed.)》1946,1(4455):813-814
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Summary Fluorescein-conjugated lectins were used to examine the reappearance of glycoproteins on the surface of 8-cell mouse embryos after treatment with proteolytic enzymes. Embryos were decompacted in calcium free medium, treated with various proteases and the process of recompaction monitored. The most effective enzymes in delaying recompaction were subtilopeptidase A and proteinase K at 1 mg/ml; the initiation of recompaction was delayed by about 5 h and 90% recompaction by 14–18 h. Papain and -chymotrypsin were only effective in the absence of calcium. The reappearance of receptors for fluorescein-conjugated Con-A, MPA, RCA-I, FBP, BSL-II and DBA was examined photometrically at 0,8–10 and 17–18 h after proteinase K treatment. There was an increase in binding of MPA, RCA-I, FBP and BSL-II in control embryos during the period of the experiment, between approx. 61 and 80 h post coitum in which embryos passed from the 8-cell stage to the 16–32 cell stage. Con-A binding remained the same and that of DBA decreased. By the time that 50% of enzyme treated embryos had recompacted (8–10 h) binding of Con-A was similar to control embryos. Binding of FBP had almost reached control levels while that of BSL-II, DBA, RCA-I and MPA had reached 60–85% of control levels. When embryos were fully compact (17–18 h) Con-A, FBP and DBA were bound in equal or slightly greater amounts to enzyme treated as to control embryos, and receptors for BSL-II, MPA and RCA-I had recovered almost to control levels. The results clearly show that the recovery of glycoproteins on the surface of 8–16 cell embryos parallels recompaction, providing further evidence for the role of these molecules in compaction. 相似文献
4.
New hybrids with d genome wheat relatives 总被引:3,自引:0,他引:3
The cytology of nine new D genome hybrids involving Triticum syriacum, Triticum ventricosum, Triticum cyclindricum, Triticum juvenale, Triticum crassum, Triticum tauschii and Triticum aestivum is described. The calculation of numerical values of the relative affinity and the patterns of chromosome pairing indicate that the D genome in T. syriacum and T. juvenale may have been substantially modified and that of T. crassum somewhat modified from that of the diploid progenitor, T. tauschii. 相似文献
5.
1-Chloromethylpyrene: a reference skin sensitizer and genotoxin 总被引:2,自引:0,他引:2
J Ashby J E Gallagher M Kohan H Tinwell I Kimber D Paton R D Callander I Chouroulinkov 《Mutation research》1990,243(4):281-289
1-Chloromethylpyrene (1-CMP) has been evaluated as a model mutagen and toxin related to the ultimate electrophiles derived from benzo[a]pyrene and 1-nitropyrene. It was mutagenic to Salmonella (greater than 100 pg/plate) and exceptionally reactive to DNA when assessed by the 32P-postlabelling technique. 1-CMP was inactive in a mouse bone micronucleus assay when administered by gavage, probably due to hydrolysis, whose kinetics have been studied (t1/2 approximately 23 min at 37 degrees C). However, as expected, it was a potent skin toxin as determined by its activity as a mitogen to mouse skin and its contact allergenicity, as determined using the local lymph node proliferative assay. It is concluded that 1-CMP will probably be a potent human skin carcinogen and contact allergen. 相似文献
6.
Monosodium glutamate (MSG) is added to many processed foods at significant levels for flavor enhancement. It is also naturally occurring at high levels in some foods. The enantiomeric composition of free glutamate in foods was examined and all foods analyzed were found to contain D -glutamate. The relative percent of D -glutamate in the food products studied depended on the origin of the glutamate. Foods to which MSG was added by the manufacturer had a high total level of MSG but a lower relative percentage of the D -enantiomer (usually less than 0.8%). In comparison, fermented foods tend to have high relative levels of D -glutamate but a lower total amount of the amino acid. The relative percent of D -glutamate in nonfermented foods containing no added MSG was also found to be low compared to fermented products. In some cases the percent D -glutamate could be related to the relative amounts of other food ingredients such as cheese. © 1994 Wiley-Liss, Inc. 相似文献
7.
Several polyploid species in the genus Triticum contain a U genome derived from the diploid T. umbellulatum. In these species, the U genome is considered to be unmodified from the diploid based on chromosome pairing analysis, and it is referred to as pivotal. The additional genome(s) are considered to be modified, and they are thus referred to as differential genomes. The M genome derived from the diploid T. comosum is found in many U genome polyploids. In this study, we cloned three repetitive DNA sequences found primarily in the U genome and two repetitive DNA sequences found primarily in the M genome. We used these to monitor variation for these sequences in a large set of species containing U and M genomes. Investigation of sympatric and allopatric accessions of polyploid species did not show repetitive DNA similarities among sympatric species. This result does not support the idea that the polyploid species are continually exchanging genetic information through introgression. However, it is also possible that repetitive DNA is not a suitable means of addressing the question of introgression. The U genomes of both diploid and polyploid U genome species were similar regarding hybridization patterns observed with U genome probes. Much more variation was found both among diploid T. comosum accessions and polyploids containing M genomes. The observed variation supports the cytogenetic evidence that the M genome is more variable than the U genome. It also raises the possibility that the differential nature of the M genome may be due to variation within the diploid T. comosum, as well as among polyploid M genome species and accessions. 相似文献
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9.
Helminthosporium maydis T Toxin Decreased Calcium Transport into Mitochondria of Susceptible Corn 总被引:7,自引:6,他引:1
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The effects of purified Helminthosporium maydis T (HmT) toxin on active Ca2+ transport into isolated mitochondria and microsomal vesicles were compared for a susceptible (T) and a resistant (N) strain of corn (Zea mays). ATP, malate, NADH, or succinate could drive 45Ca2+ transport into mitochondria of corn roots. Ca2+ uptake was dependent on the proton electrochemical gradient generated by the redox substrates or the reversible ATP synthetase, as oligomycin inhibited ATP-driven Ca2+ uptake while KCN inhibited transport driven by the redox substrates. Purified native HmT toxin completely inhibited Ca2+ transport into T mitochondria at 5 to 10 nanograms per milliliter while transport into N mitochondria was decreased slightly by 100 nanograms per milliliter toxin. Malate-driven Ca2+ transport in T mitochondria was frequently more inhibited by 5 nanograms per milliliter toxin than succinate or ATP-driven Ca2+ uptake. However, ATP-dependent Ca2+ uptake into microsomal vesicles from either N or T corn was not inhibited by 100 nanograms per milliliter toxin. Similarly, toxin had no effect on proton gradient formation ([14C]methylamine accumulation) in microsomal vesicles. These results show that mitochondrial and not microsomal membrane is a primary site of HmT toxin action. HmT toxin may inhibit formation of or dissipate the electrochemical proton gradient generated by substrate-driven electron transport or the mitochondrial ATPase, after interacting with a component(s) of the mitochondrial membrane in susceptible corn. 相似文献
10.
By the Giemsa C-banding of six rye (Secale cereale) trisomics and by crossing them to translocation tester stocks it was possible to identify the trisomics and the tester stocks so that their correspondence to the wheat homoeologous groups could be established. The Heines Hellkorn trisomics 1/23, 4/11, 4/9, 1/19, 1/21 and 3/23 were found to correspond to Sears' Chinese Spring/Imperial additions E, G, C, A, F and D respectively. These additions most probably correspond to the wheat homoeologous groups 1, 3, 4, 5, 6 and 7. 相似文献