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491.
492.
The glucosyltransferase Lgt1 is one of three glucosylating toxins of Legionella pneumophila, the causative agent of Legionnaires disease. It acts through specific glucosylation of a serine residue (S53) in the eukaryotic elongation factor 1A and belongs to type A glycosyltransferases. High-resolution crystal structures of Lgt1 show an elongated shape of the protein, with the binding site for uridine disphosphate glucose at the bottom of a deep cleft. Lgt1 shows only a low sequence identity with other type A glycosyltransferases, and structural conservation is limited to a central folding core that is usually observed within this family of proteins. Domains and protrusions added to the core motif represent determinants for the specific recognition and binding of the target. Manual docking experiments based on the crystal structures of toxin and target protein suggest an obvious mode of binding to the target that allows for efficient transfer of a glucose moiety. 相似文献
493.
494.
Summary Based on a revision of large recent collections housed at the Natural History Museum (London), Tel Aviv University and in the private collection of Yu. Verves and L. Khrokalo (Kyiv, Ukraine), new distributional data and an updated list with comments of 28 species of Middle Eastern Sarcophagidae of the subtribe Pterellina are presented. Seventeen of them are recorded for Israel, 11 for Egypt, four for Iran, two each for the Palestinian Authority, Saudi Arabia and Turkey, and one each for Jordan and the UAE. No data are known for the territories of Bahrain, Cyprus, Iraq, Kuwait, Lebanon, Oman, Qatar, Syria and Yemen. Twelve species new to science are described, including nine from Israel (Chaetapodacra montana n. sp., Eremasiomyia bicolor n. sp., E. deserta n. sp., E. fuscata n. sp., Protomiltogramma bidentata n. sp., P. serrata n. sp., Pterella hermonica n. sp., P. indigens n. sp., P. zefatica n. sp.), two from Egypt (Chaetapodacra griseola n. sp., Eremasiomyia alba n. sp.) and one from Saudi Arabia (Protomiltogramma arabica n. sp.). The male of Eremasiomyia nigra Rohdendorf, 1935 is described for the first time. One new combination of specific name is proposed ? Protomiltogramma immunita (Villeneuve, 1923), n. comb. Original keys for the identification of genera and species are proposed. An annotated list of all world genera and species and compiled data on larval habits of Pterellina are included. 相似文献
495.
Yury B. Yurov 《Journal of molecular biology》1980,136(3):339-342
Autoradiography of replicating DNA molecules isolated from individual human cells shows that the rate of DNA replication fork movement within a single cell varies from 0.2 to 1.2 μm/min with an average value of 0.5 to 0.6 μm/min. These data suggest that replication forks move at substantially different rates in different parts of the genome within a single cell. 相似文献
496.
Elena V. Artyukova Marina M. Kozyrenko Peter G. Gorovoy Yury N. Zhuravlev 《Genetica》2009,137(2):201-212
Microbiota decussata Kom. (Cupressaceae) is a subalpine species endemic to the Sikhote Alin Mountains with populations scattered throughout the
range. We used sequence data for four noncoding regions of chloroplast DNA to characterize the genetic diversity in populations
sampled from different parts of M. decussata natural range. No variation was observed in the trnT–trnF region, whereas the trnH–psbA, trnS–trnfM, and trnS–trnG regions showed polymorphisms. At the species level, we found a low nucleotide diversity (π = 0.0009) and high haplotype diversity
(h = 0.981) as well as high differentiation (ΦST = 0.420). N
ST and G
ST values suggested the existence of a phylogeographic structure in M. decussata. The observed patterns of diversity could be explained in part by ecological features of the species and its long-term persistence
throughout the range with population expansion, successive fragmentation and isolation. 相似文献
497.
Dmitry Kaluzhny Anna ShchyolkinaMichael Livshits Yury LysovOlga Borisova 《Biophysical chemistry》2009
Human genome is shown to be enriched with (GT)n stretches of lengths from 8 to 20 dinucleotides. Low temperature (T ≤ 10 °C) conformations of d(GT)n oligonucleotides (n = 7, 8, 12, 16, 20) were studied by means of circular dichroism (CD), thermal melting, ethidium bromide (EtBr) probing and single nucleotide substitutions. Rotational relaxation times for EtBr:d(GT)n complexes confirmed a monomolecular state of the oligonucleotides. CD spectra indicated involvement of all guanines of d(GT)8 and d(GT)16 in G-quartets, while dT(GT)7, d(GT)12 and d(GT)20 were shown to be only partially ordered. The schemes of the d(GT)8 and d(GT)16 folds are suggested. 相似文献
498.
Leon V. Backinowsky Yury E. Tsvetkov Nikolay F. Balan Narguiz E. Byramova Nikolay K. Kochetkov 《Carbohydrate research》1980,85(2):209-221
The reaction of sugar 1,2-thio-orthoesters in the d-gluco, d-galacto, d-manno, and l-rhamno series with primary and secondary trityl ethers of monosaccharides, in the presence of triphenylmethylium perchlorate as catalyst, affords, stereospecifically, derivatives of 1,2-trans-disaccharides in good yields. 4-Trityl ethers of benzyl 2-acetamido-3,6-di-O-acetyl-2-deoxy-α-d-glucopyranoside and methyl 2,3,6-tri-O-benzoyl-α-d-galactopyranoside exhibit low reactivity in glycosylation by thio-orthoesters. A reaction scheme for the glycosylation is discussed. 相似文献
499.
Herman Ehrlich Yury N. Elkin Alexandr A. Artoukov Valentin A. Stonik Peter P. Safronov Vasily V. Bazhenov Denis V. Kurek Valery P. Varlamov Ren�� Born Heike Meissner Gert Richter 《Marine biotechnology (New York, N.Y.)》2011,13(3):402-410
Unique skeletal formations of marine invertebrates, including representatives of Echinodermata, have the unique potential to serve as templates for bio-inspired materials chemistry, biomimetics, and materials science. The sand dollar Scaphechinus mirabilis (Agassiz, 1983) is widely distributed in the northwest of the Pacific Ocean from southern Japan to the Aleutian Islands. This animal is the main source of naphtochinone-based substances. These compounds have recently drawn medical attention for their use as cardiological and ophthalmological drugs. Unfortunately, after extraction of the naphtochinones, the residual skeletons and spines of the sand dollars were usually discarded. Here, we report the first method for the preparation of nanostructurally organized spines of S. mirabilis, using a simple enzymatic and hydrogen peroxide-based treatment. Application of this method opens the way for development of non-wasteful environmentally clean technology of sand dollars as well-known industrial marine invertebrates. 相似文献
500.
The energy of interaction of a spermine molecule with the A - and B -forms of DNA has been calculated, assuming that the molecule of spermine is fixed in the narrow groove of the DNA helix with the formation of hydrogen bonds between the amino groups of spermine and the phosphate groups of DNA. The atom–atom potentials method was used. Optimal structures for the A-DNA–spermine and B-DNA–spermine complexes are suggested. It is shown that, in agreement with the experimental data, the interaction of the spermine molecule with the A -DNA is energetically more favorable than that with the B -DNA. Two main factors are responsible for this: (1) the distance between neighboring phosphates of the chain in A -DNA (which is about 1 Å less than that in B -DNA) corresponds better to the distance between the amino groups of the propyl part of spermine; and (2) the orientation of phosphate groups in A -DNA inside the groove is preferable for complex formation with spermine to the outside groove arrangement of the phosphates in B -DNA. These conclusions are further confirmed by the calculations for DNA–propane diamine complexes. 相似文献