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171.
A novel C
2-symmetric ring-fluorinated hemin, 13,17-bis(2-carboxyethyl)-2,8,12,18-tetramethyl-3,7-difluoroporphyrinatoiron(III), has
been synthesized and was incorporated into sperm whale apomyoglobin to investigate protein-induced rhombic perturbations on
the electronic structure of the active site of myoglobin (Mb) using 19F NMR spectroscopy. NMR signals for 19F atoms introduced as substituents on the present heme in ferrous low-spin and high-spin and ferric low-spin complexes have
been observed and their shifts sharply reflect not only the electronic nature of the heme iron, but also in-plane asymmetry
of the heme electronic structure. The two-fold symmetric electronic structure of the ring-fluorinated hemin is clearly manifested
in the 19F and 1H NMR spectra of its dicyano complex. The chemical equivalence of the two fluorine atoms of the heme is removed in the active
site of myoglobin and the splitting of the two 19F NMR signals provides a quantitative probe for characterizing the rhombic perturbation of the heme electronic structure induced
by the heme-protein interaction. The in-plane asymmetry of heme electronic structures in carbonmonoxy and deoxy Mbs have been
analyzed for the first time on the basis of the shift difference between the two 19F NMR signals of the heme and is interpreted in terms of iron-ligand binding and/or the orbital ground state of the heme.
A potential utility of 19F NMR, combined with the use of a symmetric fluorinated hemin, in characterizing the heme electronic structure of myoglobin
in a variety of iron oxidation, spin, and ligation states, is presented.
Received: 23 December 1999 / Accepted: 3 April 2000 相似文献
172.
When the cells of the newly isolated marine bacterium, Vibrio alginolyticus, were inoculated on to an inorganic packing material in biofilter, and a load of ammonia of 2.4–22.5 g-N kg–1dry packing material was introduced continuously under non-sterile conditions, the average amount of NH3removed exceeded 85% over 61-d operation. The maximum removal capacity and the complete removal capacity were 22.8 g-N kg–1dry packing material dand 18.6 g-N kg–1dry packing material d, respectively, which were about four times larger than those obtained in autotrophic nitrifying sludge inoculated on the same packing material. 相似文献
173.
We found several juvenile hormone-responsive cDNAs in the bean bug, Riptortus clavatus, by using mRNA differential display (Hirai et al., 1998). One of them, a juvenile hormone-repressible cDNA, JR-3, was cloned, sequenced, characterized and identified as a transferrin (RcTf). RcTf cDNA encoded 652 amino acids with a calculated molecular weight of 71,453 Da. The deduced amino acid sequence showed significant homology with the transferin genes of several insects, Manduca sexta (43% identity), Blaberus discoidalis (43%), Aedes aegypti (43%), Drosophila melanogaster (36%), Sarcophaga peregrina (36%) and the human (25%). Antiserum was prepared by using recombinant RcTf protein expressed in Escherichia coli as an antigen. The antiserum reacted specifically with both the recombinant protein and the native protein from the bugs, with sizes of 70 and 75 kDa, respectively. The 75 kDa protein was partially purified from hemolymph of diapausing female bugs and the first ten amino acids were found to be identical to that of RcTf cDNA, indicating that the 75 kDa protein is RcTf. The tissue distribution of RcTf in the bug was examined by Western blot analysis. In diapausing animals, RcTf was detected in the fat body, hemolymph and ovary but not in the gut. In the post-diapause stage, RcTf was also detected in eggs, in addition to the fat body and ovary. These results indicate that RcTf is incorporated into the oocytes during vitellogenesis, and suggest that it may provide iron for the developing embryos. 相似文献
174.
Kazuyoshi Masuda Shunji Nagata Koichiro Hirano Yasushi Takagishi Hidematsu Hirai 《生物化学与生物物理学报:疾病的分子基础》1993,1182(2):128-132
This study was carried out to clarify the reason for elevation of serum α-fetoprotein (AFP) level of nude mice bearing hepatoma cells after treatment with monoclonal antibodies (MoAbs) to AFP. MoAbs to AFP showed no effect on the cumulative amounts of AFP secreted from human hepatoma cell line, HuH-7, in vitro. However, the treatment of nude mice bearing HuH-7N cells (HuH-7 xenograft) with MoAbs to AFP led to elevation of the serum AFP level in spite of the fact that the growth curve of HuH-7N cells was similar to that for PBS treatment. This apparent elevation of the serum AFP level is thought to be due to the slow elimination of AFP-MoAb immune complexes with little lattice structure from circulation, but not the enhancement of AFP secretion of HuH-7N cells. Thus, when using a MoAb alone or MoAb-drug conjugate, the serum AFP level should only be cautiously used as a tumor marker for evaluating the targeting immunotherapy. 相似文献
175.
Fabiani E Stadler AM Madern D Koza MM Tehei M Hirai M Zaccai G 《European biophysics journal : EBJ》2009,38(2):237-244
Changes of molecular dynamics in the α-to-β transition associated with amyloid fibril formation were explored on apomyoglobin
(ApoMb) as a model system. Circular dichroism, neutron and X-ray scattering experiments were performed as a function of temperature
on the protein, at different solvent conditions. A significant change in molecular dynamics was observed at the α-to-β transition
at about 55°C, indicating a more resilient high temperature β structure phase. A similar effect at approximately the same temperature was observed in holo-myoglobin,
associated with partial unfolding and protein aggregation. A study in a wide temperature range between 20 and 360 K revealed
that a dynamical transition at about 200 K for motions in the 50 ps time scale exists also for a hydrated powder of heat-denatured
aggregated ApoMb. 相似文献
176.
177.
Saneyoshi Ueno Yuriko Taguchi Nobuhiro Tomaru Yoshihiko Tsumura 《Conservation Genetics》2009,10(5):1477-1485
Fagus crenata Blume is widely distributed throughout Japanese cool-temperate deciduous broad-leaved forests, but there are two divergent
groups of populations in areas with contrasting winter climates separated by Japan’s Central Mountain Range. To facilitate
investigations of adaptive genetic differentiation of the species using potentially functional genes, we have collected Expressed
Sequence Tags and developed Simple Sequence Repeat markers using a cDNA library constructed from cambium and surrounding tissues.
In total, 270 primer pairs were designed, and 87 of the corresponding loci showed polymorphism in 16 individuals, with 2–21
alleles per locus and expected heterozygosities ranging from 0.06 to 0.97. EST-SSR markers developed in the present study
will be useful for genomic analyses of F. crenata populations. 相似文献
178.
GM1 epitope tetrasaccharide was synthesized by a condensation of sialyl-alpha(2-3)-gal acceptor and gal-beta(1-3)-GalN donor in a highly efficient manner. After introduction of mercaptohexanol to the tetrasaccharide, it was coupled to maleimide-activated KLH carrier protein to give the desired GM1 epitope-KLH conjugate. 相似文献
179.
l-Aspartyl l-amino acid methyl ester was synthesized using a mutant of a thermostable leucine aminopeptidase from Streptomyces cinnamoneus, D198 K SSAP, obtained in previously. A peptide of high-intensity sweetener, l-aspartyl-l-phenylalanine methyl ester, was selected as a model for demonstrating the synthesis of l-aspartyl l-amino acid methyl ester. The hydrolytic activities of D198 K SSAP toward l-aspartyl-l-phenylalanine and its methyl ester were, respectively, 74-fold and fourfold higher than those of wild type. Similarly, the
initial rate of the enzyme for l-aspartyl-l-phenylalanine methyl ester synthesis was over fivefold higher than that of wild-type SSAP in 90% methanol (v/v) in a one-pot
reaction. Furthermore, other l-aspartyl l-amino acid methyl esters were synthesized efficiently using D198 K SSAP. Results show that the substitution of Asp198 of
SSAP with Lys is effective for synthesizing l-aspartyl l-amino acid methyl ester. 相似文献
180.
Suzuki T Sugiyama K Hirai H Ito H Morita T Dohra H Murata T Usui T Tateno H Hirabayashi J Kobayashi Y Kawagishi H 《Glycobiology》2012,22(5):616-629
A lectin was purified from the mushroom Hygrophorus russula by affinity chromatography on a Sephadex G-50 column and BioAssist S cation exchange chromatography and designated H. russula lectin (HRL). The results of sodium dodecyl sulfate-polyaclylamidegel electrophoresis, gel filtration and matrix-assisted laser desorption ionization time-of-flight mass spectrometry of HRL indicated that it was composed of four identical 18.5?kDa subunits with no S-S linkage. Isoelectric focusing of the lectin showed bands near pI 6.40. The complete sequence of 175 amino acid residues was determined by amino acid sequencing of intact or enzyme-digested HRL. The sequence showed homology with Grifola frondosa lectin. The cDNA of HRL was cloned from RNA extracted from the mushroom. The open reading frame of the cDNA consisted of 528?bp encoding 176 amino acids. In hemagglutination inhibition assay, α1-6 mannobiose was the strongest inhibitor and isomaltose, Glcα1-6Glc, was the second strongest one, among mono- and oligosaccharides tested. Frontal affinity chromatography indicated that HRL had the highest affinity for Manα1-6(Manα1-3)Manβ1-4GlcNAcβ1-4GlcNAc, and non-reducing terminal Manα1-6 was essential for the binding of HRL to carbohydrate chains. The sugar-binding specificity of HRL was also analyzed by using BIAcore. The result from the analysis exhibited positive correlations with that of the hemagglutination inhibition assay. All the results suggested that HRL recognized the α1-6 linkage of mannose and glucose, especially the Manα1-6 bond. HRL showed a mitogenic activity against spleen lymph cells of an F344 rat. Furthermore, an enzyme-linked immunosorbent assay showed strong binding of HRL to human immunodeficiency virus type-1 gp120. 相似文献