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71.
72.
Characterization of glycoconjugates in the bovine endometrium and chorion by lectin histochemistry 总被引:1,自引:0,他引:1
Lectin binding patterns were examined on normal bovine endometrium and bovine placentomes during four stages of pregnancy using 13 biotinylated lectins. Lectin binding intensity increased in early pregnancy for many lectins, whereas binding to fucosyl residues decreased. Persistence of strong lectin binding later in pregnancy usually was limited to the arcade and intercotyledonary trophoblastic cells. Binding of some lectins to cell surfaces was prominent, particularly in early pregnancy. A few lectins were excellent markers for binucleate trophoblastic cells. These distinctive surface and binucleate cell binding patterns on placentomes and endometrial epithelium are useful markers of trophoblastic cell-endometrial epithelial cell surface interactions and of binucleate cell differentiation. 相似文献
73.
Kristiane Søreng Michael J Munson Christopher A Lamb Gunnveig T Bjørndal Serhiy Pankiv Sven R Carlsson Sharon A Tooze Anne Simonsen 《EMBO reports》2018,19(4)
Trafficking of mammalian ATG9A between the Golgi apparatus, endosomes and peripheral ATG9A compartments is important for autophagosome biogenesis. Here, we show that the membrane remodelling protein SNX18, previously identified as a positive regulator of autophagy, regulates ATG9A trafficking from recycling endosomes. ATG9A is recruited to SNX18‐induced tubules generated from recycling endosomes and accumulates in juxtanuclear recycling endosomes in cells lacking SNX18. Binding of SNX18 to Dynamin‐2 is important for ATG9A trafficking from recycling endosomes and for formation of ATG16L1‐ and WIPI2‐positive autophagosome precursor membranes. We propose a model where upon autophagy induction, SNX18 recruits Dynamin‐2 to induce budding of ATG9A and ATG16L1 containing membranes from recycling endosomes that traffic to sites of autophagosome formation. 相似文献
74.
75.
Characterization of a transposon Tn916-generated mutant of Haemophilus ducreyi 35000 defective in lipooligosaccharide biosynthesis. 总被引:2,自引:0,他引:2 下载免费PDF全文
B W Gibson A A Campagnari W Melaugh N J Phillips M A Apicella S Grass J Wang K L Palmer R S Munson Jr 《Journal of bacteriology》1997,179(16):5062-5071
To define the role of the surface lipooligosaccharide (LOS) of Haemophilus ducreyi in the pathogenesis of chancroid, Tn916 mutants of H. ducreyi 35000 defective in expression of the murine monoclonal antibody (MAb) 3F11 epitope on H. ducreyi LOS were identified by immunologic screening. One mutant, designated 1381, has an LOS which lacks the MAb 3F11 epitope and migrates with an increased mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The gene disrupted by the Tn916 element in strain 1381 was identified by cloning the sequences flanking the Tn916 element. The sequences were then used to probe a lambda DASHII genomic library. In strain 1381, Tn916 interrupts a gene which encodes an open reading frame (ORF) with an Mr of 40,246. This ORF has homology to the product of the rfaK gene of Escherichia coli. The major LOS glycoform produced by strain 1381 was analyzed by using a combination of mass spectrometry, linkage and composition analysis, and 1H nuclear magnetic resonance spectroscopy. The major LOS species was found to terminate in a single glucose attached to the heptose (L-glycero-D-manno-heptose, or Hep) trisaccharide core. In the wild-type strain 35000, glucose serves as the acceptor for the addition of the D-glycero-D-manno-heptose (or DDHep), which extends to form the mature branch of the H. ducreyi LOS. This mature oligosaccharide is in turn partially capped by the addition of sialic acid (NeuAc), i.e., NeuAc2 alpha-->3Gal beta1-->4GlcNAc beta1-->3Gal beta1-->4DDHep alpha1-->6Glc beta1 (W. Melaugh et al., Biochemistry 33:13070-13078, 1994). Since this LOS terminates prior to the addition of the branch DD-heptose, this gene is likely to encode the D-glycero-D-manno-heptosyltransferase. Strain 1381 exhibits a significant reduction in adherence to and invasion of primary human keratinocytes. This defect was complemented by the cloned heptosyltransferase gene, indicating that the terminal portion of the LOS oligosaccharide plays an important role in adherence to human keratinocytes. 相似文献
76.
S. B. Chaplin M. M. Munson S. T. Knuth 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(3):197-203
The effect of various activity regimes on metabolism of pigeon pectoralis was examined by measurement of blood lactate following
exercise, total lactate dehydrogenase activity of pectoral muscle, and proportions of specific isoenzymes of pectoral muscle
lactate dehydrogenase. Sprint-trained birds had the highest pectoral muscle lactate dehydrogenase activity (1409 IU · g−1 wet tissue), while endurance-trained birds had the highest peak lactate levels (287 mg · dl−1, extrapolated from decay curves) and fastest half-time of the lactate response (4.8 min) following exercise, but the lowest
lactate dehydrogenase activity (115 IU · g−1 wet tissue). Immobilization of one wing for 3 weeks following endurance training produced a marked increase in lactate dehydrogenase
activity of the immobilized muscle, compared to that in the contralateral pectoralis and endurance-trained muscle. Aerobic
forms of the lactate dehydrogenase enzyme (that favor conversion of lactate to pyruvate) predominated in pectoral muscle of
endurance-trained birds, while cage-confined birds exhibited primarily the anaerobic isoenzymes. These results demonstrate
that conversion of pectoral muscle lactate dehydrogenase isoenzymes, total lactate dehydrogenase activity, and half-time of
lactate response after exercise is dependent on activity regime in pigeons. In this respect, pigeon pectoral muscle responds
to training and disuse in a manner similar to that of mammalian skeletal muscle.
Accepted: 10 September 1996 相似文献
77.
What makes a protein a protein? Hydrophobic core designs that specify stability and structural properties. 总被引:10,自引:8,他引:2 下载免费PDF全文
M. Munson S. Balasubramanian K. G. Fleming A. D. Nagi R. O'Brien J. M. Sturtevant L. Regan 《Protein science : a publication of the Protein Society》1996,5(8):1584-1593
Here we describe how the systematic redesign of a protein's hydrophobic core alters its structure and stability. We have repacked the hydrophobic core of the four-helix-bundle protein, Rop, with altered packing patterns and various side chain shapes and sizes. Several designs reproduce the structure and native-like properties of the wild-type, while increasing the thermal stability. Other designs, either with similar sizes but different shapes, or with decreased sizes of the packing residues, destabilize the protein. Finally, overpacking the core with the larger side chains causes a loss of native-like structure. These results allow us to further define the roles of tight residue packing and the burial of hydrophobic surface area in the construction of native-like proteins. 相似文献
78.
Linkers that connect repeating secondary structures fall into conformational classes based on distance and main-chain torsion clustering. A data set of 300 unique protein chains with low pairwise sequence identity was clustered into only a few groups representing the preferred motifs. The linkers of two to eight residues for the nonredundant data set are designated H-Ln-H, H-Ln-E, E-Ln-H, E-Ln-E, where n is the length, H stands for alpha-helices, and E for beta-strands. Most of the clusters identified here corroborate earlier findings. However, 19 new clusters are identified in this paper, with many of them having seven and eight residue linkers. In our first analysis, the secondary structures flanking the linkers are both interacting and noninteracting and there is no precise angle of orientation between them. A second analysis was performed on a set of proteins with restricted orientations for the flanking elements, namely, mainly alpha class of proteins with orthogonal architecture. Two definite clusters are identified, one corresponding to linkers of orthogonal helices and the other to linkers of antiparallel helices. Loops forming binding sites or involved in catalytic activity are important determinants of the function of proteins. Although the structural conservation of the residues around the catalytic triad of serine proteases has been studied widely, there has not been a systematic analysis of the conformation of the loops that contain them. Residues of the catalytic triad reside in the linkers of beta-strands, with varying lengths of more than eight residues. Here, we analyze the structural conservation of such linkers by superposition, and observe a conserved structural feature of the linkers incorporating each of the three residues of the catalytic triad. 相似文献
79.
80.
Diversity of the outer membrane protein P2 gene from major clones of Haemophilus influenzae type b 总被引:13,自引:1,他引:12
In previous studies, it has been demonstrated that outer membrane protein P2 from Haemophilus influenzae type b has porin activity and that antibody directed against P2 is protective in an infant rat bacteraemic model. Outer membrane protein subtyping has been employed to subclassify type b Haemophilus isolates. Strain MinnA has the outer membrane protein subtype 1H and is representative of the dominant clonal group of disease-producing isolates in the United States. In the present study, the P2 gene from strain MinnA was employed to probe EcoRI- and Pvull-digested chromosomal DNA from 24 Haemophilus influenzae type b isolates representative of the common outer membrane protein subtype groups observed throughout the world. Restriction fragment length polymorphisms were identified for the members of the outer membrane protein subtype 3L group, but not for the other subtypes examined. The P2 gene from each of four prototype isolates was then cloned, sequenced and compared to the previously reported sequence of the strain MinnA gene. The P2 gene from each of two isolates with the outer membrane protein subtype 3L was identical to the MinnA P2 sequence. The P2 gene from a subtype 2L isolate differed by a single nucleotide and the gene from a subtype 6U isolate differed by 13 nucleotides. Thus, the P2 protein is highly conserved among type b isolates. 相似文献