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401.
Rapid detection of genetic contamination is critical in mouse studies involving inbred strains. During a Quantitative Trait Locus (QTL) study using simple sequence length polymorphism (SSLP) markers, we noticed heterozygosity at some loci of a commercially available inbred C57BL/6N mouse strain, suggesting a contamination by another mouse strain. A panel of 100 single-nucleotide polymorphism (SNP) markers was used to confirm and specify the genetic contamination suspected. Retrospective analyses demonstrated that the contamination took place as early as autumn 2003 and has persisted ever since at a fairly constant level. Contaminating alleles most probably originated from a DBA strain. Our data demonstrate the suitability of SNP markers for rapid detection and identification of the source of genetic contamination. Further, our results show the importance of a state-of-the-art genetic monitoring of the authenticity of murine inbred strains. 相似文献
402.
403.
Behaviour of granular starches in low-pressure glow plasma 总被引:1,自引:0,他引:1
Cheng-yi Lii Chia-ding Liao Leszek Stobinski Piotr Tomasik 《Carbohydrate polymers》2002,49(4):1894-507
Granular starches of nine botanical origins were exposed to low-pressure glow plasma generated in the air from either a high voltage DC supply or an AC inductor. Experiments with low energy air-plasma (10−2 Torr) and starches provided insight into some details of their surface structure. Starches were partly oxidized to carboxylic starches and partly depolymerized. Their affinity to plasma depended on their botanical origin. The structure of starch granules seemed to be a crucial factor, which determined the behaviour of starches in plasma. Lipids and/or proteins stabilized polysaccharides to plasma being preferentially decomposed. 相似文献
404.
405.
Glycerate kinase (GK; EC 2.7.1.31) from maize (Zea mays L.) leaves was purified by a sequence of ammonium-sulfate precipitations and chromatography on diethylaminoethyl-cellulose, hydroxyapatite, Sephadex G-75SF and dye ligand (Green A) columns. The purest preparation was almost 1300-fold enriched and had a specific activity of 68 mol · min-1 · (mg protein) -1. The enzyme was a monomer of a relative molecular mass (Mr) of 44 kDa (kdalton) as determined by gel filtration, electrophoresis in dissociating conditions and by immunoblots. The enzyme was only weakly recognized by polyclonal antibodies against purified spinach GK, indicating substantial differences in molecular structure of the two proteins. Highly reducing conditions stabilized GK activity and were required for activation of crude leaf enzyme. The enzyme had a broad pH optimum of 6.8–8.5, and formed 3-phosphoglycerate and ADP as reaction products. Apparent K
ms for D-glycerate and Mg-ATP were 0.11 and 0.25 mM, respectively. The enzyme was strongly affected by a number of phosphoesters, especially by 3-phosphoglycerate (K
i= 0.36 mM), fructose bisphosphates and nucleoside bisphosphates. Inhibition by 3-phosphoglycerate was competitive to Mg-ATP and noncompetitive to D-glycerate. Pyruvate was found noncompetitive to D-glycerate (K
is=4 mM). The ratio of stromal concentration of Mg-ATP to phosphoesters, particularly to 3-phosphoglycerate, may be of importance in the regulation of GK during C4-photosynthesis.Abbreviations DEAE
diethylaminoethyl
- kDa
kdalton
- GAP-DH
glyceraldehyde phosphate dehydrogenase
- GK
glycerate kinase
- LDH
lactate dehydrogenase
- 2-ME
2-mercaptoethanol
- Mr
relative molecular mass
- PEP
phosphoenolpyruvate
- PGA(PK)
phosphoglycerate (phosphokinase)
- PK
pyruvate kinase
- SDS-PAGE
sodium dodecyl sulfatepolyacrylamide gel electrophoresis 相似文献
406.
407.
The population growth and biomass production of the pitcher-plant (Sarracenia purpurea L.) inquiline, Habrotocha rosa Donner
(Rotifera: Bdelloidea), its consumption by other pitcher-plant inqulines, and its excretion of phosphorus (PO4–P) and nitrogen
(NO3–N and NH4–N), were investigated in laboratory experiments. Observed population growth and production rate of H. rosa
were higher at pH 4 (2.3 rotifers d-1) than at pH 3 (1.3 rotifers d-1), 5 (1.9 rotifers d-1), or 6 (0.8 rotifers d-1). Populations
of H. rosa are an abundant and reliable food source for larvae of the dipteran inqulines Wyeomyia smithii (Coq.) and Blaesoxipha
fletcheri (Aldrich) that co-occur with H. rosa in S. purpurea pitchers. Abundance of H. rosa within a pitcher is negatively
associated with abundance of dipteran larvae, and these larvae consume rotifers in direct proportion to rotifer density (Type
I functional response). Habrotrocha rosa may also account for the majority of the plant's supply of N and P. An average population
of rotifers in the field (∼400 per pitcher) can excrete ∼5.2 μg NO3-N, ∼3.91 μg NH4-N, and ∼18.4 μg PO4–P per day into a single
leaf, and excretion rate is independent of water pH. Over the six-month growing season of pitcher-plants in Massachusetts,
U.S.A., we estimate that rotifers could supply 8.8–43 mg of N and 18.2–88 mg of P. These values far exceed the amount of N
and P previously estimated to be supplied annually to the plants through insect capture or rainfall.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
408.
Marek Jasionowski Leszek ankiewicz Wiesaw Wiczk Elwira Gwizdaa Zbigniew Grzonka 《Letters in Peptide Science》1998,5(5-6):371-374
Conformational features of the neuropeptide pituitary adenylate cyclase activating polypeptide (1–27) (PACAP(1–27)) and its shorter fragments (1–5), (7–11) and (14–27) were studied by circular dichroism (CD) and fluorescence spectroscopy. The obtained CD spectra revealed that only PACAP(1–27) and the fragment (14–27) possess some content of an organized structure – the -helix. This C-terminal, helical part of the peptides is important for receptor binding as it provides a stable structure that can reside in the ordered lipid region of the receptor site in the membrane, while the primary biological function of the hormone resides in the N-terminal, disordered part. Fluorescence studies have revealed that the tyrosine residue located in the helical region of PACAP has a higher quantum yield and a longer average lifetime than the tyrosine in the N-terminus, probably due to a shielding effect of the hydrophobic cluster around Tyr22. 相似文献
409.
PCR amplification of cDNA prepared from poly(A)+ RNA from aerial parts of Arabidopsis thaliana, using degenerate nucleotide primers based on conserved regions between the large and small subunits of ADP-glucose pyrophosphorylase (AGP), yielded four different cDNAs of ca. 550 nucleotides each. Based on derived amino acid sequences, the identities between the clones varied from 49 to 69%. Sequence comparison to previously published cDNAs for AGP from various species and tissues has revealed that three of the amplified cDNAs (ApL1, ApL2 and ApL3) correspond to the large subunit of AGP, and one cDNA (ApS) encodes the small subunit of AGP. Both ApL1 and ApS were subsequently found to be present in a cDNA library made from Arabidopsis leaves. All four PCR products are encoded by single genes, as found by genomic Southern analysis. 相似文献
410.
Stable co-transformation of maize protoplasts with gusA and neo genes 总被引:10,自引:0,他引:10
Leszek A. Lyznik Randy D. Ryan Steven W. Ritchie Thomas K. Hodges 《Plant molecular biology》1989,13(2):151-161
An efficient co-transformation protocol using polyethylene glycol was developed for Zea mays L. (cv. A188 × BMS) protoplasts isolated from suspension culture cells. Co-transformation was accomplished by using plasmid constructions containing -glucuronidase (gusA) or neomycin phosphotransferase (neo) gene coding sequences; both were under control of the CaMV 35S promoter. Protoplast culture and transformation conditions were optimized to assure efficient recovery of transformed cells. The overall efficiency of transformation was 1 × 10–4 (calculated per viable protoplast plated). Among kanamycin-resistant lines, 50% showed a high level of GUS activity (above one unit). Southern blot hybridization confirmed the presence of numerous gusA and neo coding sequences in the maize genome. In two analyzed lines, integrated sequences appeared to be organized in tandem head-to-tail repeats. Results also indicated that the integrated sequences were partially methylated. 相似文献