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1.
First appearing in 2000, and with 20,000 copies sold as it entered its sixth printing in 2004, Richard Trudgen's Why Warriors Lie down and Die is a minor publishing phenomenon. Although scholarly forums have generally ignored the book, Christian media outlets, the popular press and neo‐conservative political activists have enthusiastically received and promoted it. An examination of the merits of Why Warriors Lie down and Die suggests that its popularity is only partly explained by original observations or insights on the part of the author. The most important explanation, and implication, of the book's remarkable take‐up lies in the opportune way in which it corresponds with now ascendant neo‐conservative political perspectives on indigenous policy. 相似文献
2.
Prolactin binding activity was studied in suspensions of cells which had been enzymatically dissociated from R3230AC mammary tumors, 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumors and lactating rat mammary glands. Prolactin bound specifically with high affinity (apparent binding affinity = 4.0 X 10(9) M-1) to R3230AC tumor cells. Hormone binding at room temperature was proportional to cell number and increased with time of incubation up to 120-180 min. Prolactin binding to R3230AC tumor cells from diabetic animals was reduced by about 50%. Specific prolactin binding activity was also demonstrated in preparations of cells from DMBA-induced tumors and lactating mammary gland. The levels of hormone binding in both dissociated cells and subcellular particles prepared from these tissues varied as follows: DMBA-induced tumors > lactating mammary gland > R3230AC mammary adenocarcinoma. 相似文献
3.
Directed mutagenesis of the dicyclohexylcarbodiimide-reactive carboxyl residues in beta-subunit of F1-ATPase of Escherichia coli 总被引:1,自引:0,他引:1
Previous studies in which dicyclohexylcarbodiimide (DCCD) was used to inactivate F1-ATPase enzymes have suggested that two glutamate residues in the beta-subunit are essential for catalysis. In the Escherichia coli F1-ATPase, these are residues beta-Glu-181 and beta-Glu-192. Oligonucleotide-directed mutagenesis was used to change these residues to beta-Gln-181 and beta-Gln-192. The beta-Gln-181 mutation produced strong impairment of oxidative phosphorylation in vivo and also of ATPase and ATP-driven proton-pumping activities in membranes assayed in vitro. A low level of each activity was detected and an F1-ATPase appeared to be assembled normally on the membranes. Therefore, it is suggested that the carboxyl side chain at residue beta-181 is important, although not absolutely required, for catalysis in both directions on E. coli F1-ATPase. The beta-Gln-192 mutation produced partial inhibition of oxidative phosphorylation in vivo and membrane ATPase activity was reduced by 78%. These results contrast with the complete or near-complete inactivation seen when E. coli F1-ATPase is reacted with DCCD and imply that DCCD-inactivation is attributable more to the attachment of the bulky DCCD molecule than to the derivatization of the carboxyl side chain of residue beta-Glu-192. M. Ohtsubo and colleagues (Biochem. Biophys. Res. Commun. (1987) 146, 705-710) described mutagenesis of the F1-beta-subunit of thermophilic bacterium PS3. Mutations (Glu----Gln) of the residues homologous to Glu-181 and Glu-192 of E. coli F1-beta-subunit both caused total inhibition of ATPase activity. Therefore, there was a marked difference in results obtained when the same residues were modified in the PS3 and E. coli F1-beta-subunits. 相似文献
4.
J Weber R S Lee E Grell J G Wise A E Senior 《The Journal of biological chemistry》1992,267(3):1712-1718
1) Using a combination of site-directed mutagenesis and fluorescence spectroscopy we have studied the location and function of residue beta Y331 in the catalytic site of Escherichia coli F1-ATPase. The fluorescent analog lin-benzo-ADP was used as a catalytic-site probe, and was found to bind to three sites in normal F1, with Kd1 = 0.20 microM and Kd2,3 = 5.5 microM. lin-Benzo-ATP was a good substrate for hydrolysis. 2) The mutants investigated were beta Y331F, L, A and E. kcat/KM for ATP hydrolysis in purified F1 was reduced according to the series Y greater than or equal to F greater than L greater than A greater than E, with E being severely impaired; concomitant decreases in binding affinity for lin-benzo-ADP were seen. 3) Fluorescence properties of lin-benzo-ADP bound to F1 differed widely, depending on the residue present at position beta 331. Red shifts of excitation and emission spectra occurred with F and L residues, but not with Y, A, or E. There was strong quenching of fluorescence with wild-type (Y), partial quenching with A, and no quenching with F, L, or E. 4) We conclude that (a) the environment around the bound adenine moiety in the catalytic site is nonpolar, (b) residue beta 331 is part of the adenine-binding subdomain and when tyrosine is the residue, the phenolic hydroxyl makes direct interaction with the fluorophore, (c) an aromatic residue is not absolutely required at position beta 331 for catalytic function, but an increase in polarity leads to functional impairment, and (d) in terms of fluorescence response of bound lin-benzo-ADP all three catalytic sites behaved the same. 5) F1 from mutant beta Y297F bound lin-benzo-ADP with the same fluorescence and binding characteristics as normal F1, and catalytic properties were similar to normal. Therefore, there was no reason to conclude that residue beta Y297 is involved in binding the adenine moiety of ATP. 相似文献
5.
D R Bielefeld R M Senior S Y Yu 《Biochemical and biophysical research communications》1975,67(4):1553-1559
A new, highly sensitive and specific assay for elastolytic activity is described which employs insoluble elastin randomly labeled with [14C]. The substrate was prepared by labeling amino groups of the protein in vitro with [14C] methyl groups by reductive alkylation. The substrate was used to quantitate elastolytic activity from human leukocytes and to compare leukocytic elastase with pancreatic elastase. Purified human leukocytic elastase was approximately one-fourth as active as pancreatic elastase. Similar difference between leukocytic elastase and pancreatic elastase activities was found when the enzymes were tested against succinyl-L-alanyl-L-alanyl-L-alanine-p-nitroanilide, but not when t-BOC-L-alanine-p-nitrophenyl ester was used. 相似文献
6.
D. E. Zamboulis J. M. Senior P. D. Clegg J. A. Gallagher S. D. Carter P. I. Milner 《Purinergic signalling》2013,9(3):383-393
Purinergic pathways are considered important in pain transmission, and P2X receptors are a key part of this system which has received little attention in the horse. The aim of this study was to identify and characterise the distribution of P2X receptor subtypes in the equine digit and associated vasculature and nervous tissue, including peripheral nerves, dorsal root ganglia and cervical spinal cord, using PCR, Western blot analysis and immunohistochemistry. mRNA signal for most of the tested P2X receptor subunits (P2X1–5, 7) was detected in all sampled equine tissues, whereas P2X6 receptor subunit was predominantly expressed in the dorsal root ganglia and spinal cord. Western blot analysis validated the specificity of P2X1–3, 7 antibodies, and these were used in immunohistochemistry studies. P2X1–3, 7 receptor subunits were found in smooth muscle cells in the palmar digital artery and vein with the exception of the P2X3 subunit that was present only in the vein. However, endothelial cells in the palmar digital artery and vein were positive only for P2X2 and P2X3 receptor subunits. Neurons and nerve fibres in the peripheral and central nervous system were positive for P2X1–3 receptor subunits, whereas glial cells were positive for P2X7 and P2X1 and 2 receptor subunits. This previously unreported distribution of P2X subtypes may suggest important tissue specific roles in physiological and pathological processes. 相似文献
7.
An evaluation of the utility of SSR loci as molecular markers in maize (Zea mays L.): comparisons with data from RFLPS and pedigree 总被引:8,自引:0,他引:8
J. S. C. Smith E. C. L. Chin H. Shu O. S. Smith S. J. Wall M. L. Senior S. E. Mitchell S. Kresovich J. Ziegle 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(1-2):163-173
The utility of 131 simple sequence repeat (SSR) loci to characterize and identify maize inbred lines, validate pedigree,
and show associations among inbred lines was evaluated using a set of 58 inbred lines and four hybrids. Thirteen sets of inbred
parent-progeny triplet pedigrees together with four hybrids and their parental lines were used to quantify incidences of scoring
that departed from expectations based upon simple Mendelian inheritance. Results were compared to those obtained using 80
restriction fragment length polymorphism (RFLP) probes. Over all inbred triplets, 2.2% of SSRs and 3.6% of RFLP loci resulted
in profiles that were scored as having segregated in a non-Mendelian fashion. Polymorphic index content (PIC, a measure of
discrimination ability) values ranged from 0.06 to 0.91 for SSRs and from 0.10 to 0.84 for RFLPs. Mean values for PIC for
SSRs and RFLPs were similar, approximately 0.62. However, PIC values for nine SSRs exceeded the maximum PIC for RFLPs. Di-repeats
gave the highest mean PIC scores for SSRs but this class of repeats can result in “stutter” bands that complicate accurate
genotyping. Associations among inbreds were similar for SSR and RFLP data, closely approximating expectations from known pedigrees.
SSR technology presents the potential advantages of reliability, reproducibility, discrimination, standardization and cost
effectiveness over RFLPs. SSR profiles can be readily interpreted in terms of alleles at mapped loci across a broad range
of maize germ plasm. Consequently, SSRs represent the optimum approach for the identification and pedigree validation of maize
genotypes compared to other currently available methods.
Received: 15 January 1997 / Accepted: 28 February 1997 相似文献
8.
By use of the radiolabelled substrates sodium [1–14 C] acetate, sodium [2–14 C] acetate, NaH14 CO3 and 14 CH3 OH, three of the possible methanogenic pathways in fermenting refuse were confirmed. Due to the absence of a methanol pool, however, the relative contribution of each could not be determined. Circumstantial evidence for an operative trimethylamine pathway was gained but not confirmed whilst preliminary attempts to stimulate methanogenesis in refuse by supplementation with mono-and dimethylamine proved unsuccessful. 相似文献
9.
1. The effects of the hypoglycaemic compound pent-4-enoic acid, and of four structurally related non-hypoglycaemic compounds (pent-2-enoic acid, pentanoic acid, cyclopropanecarboxylic acid and cyclobutanecarboxylic acid), on several reactions in rat liver mitochondria were determined. 2. The use of manometric techniques for measurements of oxidations and of phosphorylation is critically discussed. 3. Pent-4-enoic acid and pentanoic acid uncoupled oxidative phosphorylation at low concentrations, but usually by not more than about 50%. 4. All the compounds, except cyclobutanecarboxylic acid, strongly inhibited the oxidation of pyruvate and 2-oxoglutarate, but the oxidations of succinate, citrate and 3-hydroxybutyrate were not strongly inhibited. 5. All the compounds, except cyclobutanecarboxylic acid, inhibited decarboxylation of [1-(14)C]pyruvate with ferricyanide as electron acceptor. 6. All the compounds, except pent-2-enoic acid, caused mitochondrial swelling after a time-lag. 相似文献
10.
Aqueous solutions of poly-L -tyrosine were studied by potentiometric titrations, light-scattering measurements, and infrared spectroscopy in order to characterize the conformational changes the macromolecules exhibit when the hydrogen-ion concentration of the solutions is varied. It was found that when the pH of the system at 25°C is lowered from a value of about 13 the poly-L -tyrosine molecules undergo a random-coil to β-structure conformation change at pH 11.5. It appears, that under the experimental conditions used, the formation of the β structure is an intramolecular process which involves the folding of the polymer backbone into several hairpins of antiparallel β structure. On further lowering of the pH of the solutions aggregation (pH 11.35) and subsequently precipitation (pH 11.2) takes place. Since the apparent pK of the polymer does not show a drastic change during the random-coil to β-structure conformation change, it was concluded, that the therinodynamic driving force for this conformation change is mainly due to the electrostatic effect of the partially charged side chains of the poly-L -tyrosine molecules. 相似文献