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51.
Pathological and microbiological studies were conducted on lesions in the lungs of 194 calves from mass rearing facilities. Macroscopically, the lesions were classified into six forms: nonlesion, atelectasis, mild pneumonia, moderate pneumonia, advanced pneumonia, and advanced pneumonia accompanied with abscess. Histopathological examination revealed bronchopneumonia in most of the calves. Lesions more advanced than moderate pneumonia were complicated with desquamation, severe exudation, and necrosis. Bacteriologically, Pasteurella sp. was isolated often in combination with Staphylococcus sp. from about a half of the atelectatic cases. With the development of pneumonic lesions, Pasteurella sp. was isolated at a high frequency in combination with Haemophilus sp., Streptococcus sp., and Corynebacterium sp. Prominent necrosis was more often seen in cases with Pasteurella haemolytica isolated than in cases with only Pasteurella multocida isolated. Mycoplasma sp. and Ureaplasma sp. were isolated from distinctly pneumonic lesions. Advanced pneumonic lesions were observed in many calves over 30 days of age. The importance of environmental and managerial improvement was also emphasized, since calf pneumonia tended to break out in facilities under unsatisfactory conditions in the present work. 相似文献
52.
Masayoshi Ono John W. Perry Takami Oka 《In vitro cellular & developmental biology. Plant》1981,17(2):121-128
Summary Cortisol was previously shown to elicit a concentration-dependent inhibition of α-lactalbumin accumulation in midpregnant
mouse mammary gland cultured in medium containing optimal concentrations of 5 μg/ml prolactin and insulin. In contrast, casein
accumulation under these conditions was progressively stimulated by addition of increasing amounts of cortisol (Ono, M.; Oka,
T. Cell 19: 473–480; 1980). In the present study we found that in the presence of a suboptimal concentration of 0.5 μg/ml
prolactin, 2.8×10−9
M to 2.8×10−7
M cortisol stimulated α-lactalbumin accumulation. Furthermore, higher concentrations of cortisol produced a smaller inhibition
of α-lactalbumin accumulation as compared to that obtained in cultures containing 5 μg/ml prolactin. The maximal increase
in α-lactalbumin accumulation attained in the presence of 1.4×10−8
M cortisol, 0.5 μg/ml prolactin, and insulin was comparable to that observed in culture containing 5 μg/ml prolactin and insulin.
Similar results were obtained in a cortisol concentration-response study of α-lactalbumin accumulation in cultures containing
a suboptimal concentration of 0.5 μg/ml human placental lactogen. Measurement of the rate of α-lactalbumin synthesis in cultured
tissue indicated that the opposing effects of low and high concentrations of cortisol on α-lactalbumin accumulation involved
an alteration in the rate of synthesis of the milk protein. In contrast to α-lactalbumin, the synthesis of casein was stimulated
in a concentration-dependent manner by addition of cortisol that acted synergistically with either 0.5 μg/ml or 5 μg/ml prolactin.
The maximal increases were obtained in the presence of 2.8×10−6
M cortisol. These results indicated that the action of cortisol on α-lactalbumin accumulation can be modulated by the concentration,
of prolactin and suggest that the interplay between cortisol and prolactin in regulation of α-lactalbumin synthesis may be
different from that involved in casein synthesis. 相似文献
53.
Stereochemistry of the biomimetic reduction of α-keto esters with NAD(P)H-model compounds has been investigated. The model compound with the R-configuration reduces the α-keto esters to the (R)-α-hydroxy esters, whereas (S)-α-hydroxy esters are afforded by the reduction with the S-configurational model compounds. It has been concluded that pro-R and -S hydrogens of the model compounds with R- and S-configuration, respectively, contribute predominantly to the reduction. 相似文献
54.
alpha-Chymotrypsin [EC 3.4.21.1] catalyzed the syntheses of peptide bonds with various N-acylated amino acids or peptides having aromatic or hydrophobic amino acid residues at the C-terminal position as carboxyl components, and amino acid derivatives, peptides or their derivatives as amine components. A neutral pH was most efficient and quite high concentrations of alpha-chymotrypsin and starting materials were required for synthesis. Four amine components, hydrophobic or bulky amino acid residues were useful at the N-terminal position. Stereospecificity was also observed at the N-terminal position of amine components. Peptide synthesis was not usually seen when the products were soluble in the reaction mixture. This could be partly overcome by increasing the concentration of either the carboxyl or the amine component to more than ten times that of the other. 相似文献
55.
Twenty-seven isolates of citrate-positive variants of Escherichia coli were obtained from domestic pigeons, pigs, cattle, and horses. With the exception of citrate utilization, all isolates closely resembled typical E. coli in their biochemical reactions. These isolates were multiply resistant to antibiotics in in vitro susceptibility tests. Transfer experiments of multiple-drug resistance to the E. coli K-12 strain showed that all citrate-positive isolates from domestic pigeons, pigs, and cattle, resistant to three or more drugs, carried R plasmids showing temperature-sensitive transfer. 相似文献
56.
M Kawaichi C Oka R Reeves M Kinoshita T Honjo 《The Journal of biological chemistry》1991,266(27):18387-18394
We have constructed a plasmid, pLTR100, which contains human interleukin 2 receptor light (IL-2R L) chain cDNA in the inverted orientation relative to the upstream SV40 promoter. The cDNA segment is flanked by the immunoglobulin gene recombination signal sequences so that the cDNA segment can invert and the human IL-2R L chain is subsequently expressed under the control of the SV40 promoter. A murine pre-B cell line, 38B9, transfected with pLTR100 began to express the human IL-2R L chain on the cell surface. The frequency of human IL-2R L chain positive cells increased almost linearly up to 50% for 60 days of culture after transfection. Southern blot analysis and sequencing of the DNA fragments at the recombination junction confirmed that the cDNA segment was inverted in a signal sequence-dependent manner by the variable-diversity-joining recombination process. Transgenic mice bearing the recombination substrate DNA similar to pLTR100 expressed the human IL-2 L chain in the spleen, thymus, and bone marrow, but not in the other tissues examined at the detectable level. Both IgM- and CD3-positive cells expressed the human IL-2R L chain, indicating that this artificial DNA can serve as a substrate for recombination both in B- and T-cells and that another DNA segment may be necessary to confer the cell-type specificity on the substrate DNA. 相似文献
57.
H Katagiri T Asano Y Shibasaki J L Lin K Tsukuda H Ishihara Y Akanuma F Takaku Y Oka 《The Journal of biological chemistry》1991,266(12):7769-7773
GLUT1 glucose transporter cDNA was modified to introduce a single amino acid substitution of leucine for tryptophan 412, a putative cytochalasin B photo-affinity labeling site. Although the mutated transporter was expressed into plasma membranes of Chinese hamster ovary cells, glucose transport activity of the mutated transporter was observed to be only 15-30% of that of the wild-type GLUT1 when glucose transport activity was assessed by 2-deoxyglucose uptake at 0.1-10 mM concentrations. Analysis of glucose uptake kinetics depict that a mutation induced a 3-fold decrease in turnover number and a 2.5-fold increase in Km compared with the wild-type GLUT1. Importantly, cytochalasin B labeling was not abolished but decreased by 40%, and cytochalasin B binding was also decreased. In addition, the results obtained with side-specific glucose analogs suggested that the outer glucose binding site of the mutant appeared intact but the inner binding site was modulated. These results indicate 1) tryptophan 412 is not a cytochalasin B labeling site(s), although this residue is located in or close to the inner glucose binding site of the GLUT1 glucose transporter, 2) substitution of leucine for tryptophan 412 decreases the intrinsic activity of GLUT1 glucose transporter, which is definable as the turnover number/Km, to approximately 15% of that of the wild-type. 相似文献
58.
59.
A J Conley S E Graham-Lorence M Kagimoto M C Lorence B A Murry K Oka D Sanders J I Mason 《Biochimica et biophysica acta》1992,1130(1):75-77
We describe the isolation and characterization of a cDNA encoding the complete porcine neonatal testis 17 alpha-hydroxylase/C-17,20-lyase cytochrome P-450. The deduced amino acid sequence is 509 amino acids in length. 相似文献
60.
Coated pits and asialoglycoprotein receptors redistribute to the substratum during hepatocyte adhesion to galactoside surfaces 总被引:1,自引:0,他引:1
Rat hepatocytes bind in a sugar-specific and concentration-dependent manner to flat polyacrylamide matrices containing covalently attached galactosyl (Gal) groups. Previous studies (Weigel, P.H., J. Cell Biol. 87, 855, 1980) concluded that binding was likely mediated by the asialoglycoprotein receptor. Here we confirm that adhesion is mediated by this receptor, since cell binding is inhibited by antireceptor antibody and a threshold binding response is also observed when hepatocytes adhere to surfaces coated with asialoorosomucoid, a ligand for this receptor. Cells that had bound to a Gal surface and were then sheared from the surface left a membrane patch behind on the substratum. The cytoplasmic side of these plasma membrane patches was visualized on the substratum by indirect immunofluorescence using antireceptor antibody or anticlathrin antibody. The density of punctate coated pits, visualized with the latter antibody, was enriched in a circular membrane region of about 4 microns 2 area that mediated cell binding. This zone also contained concentrated receptors, although the staining pattern with antireceptor antibody was more uniform and less punctate. The results show that both asialoglycoprotein receptors and coated pits are redistributed at the substratum interface on hepatocytes bound to Gal surfaces. 相似文献