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51.
Re-localization of nuclear DNA helicase II during the growth period of bovine oocytes 总被引:2,自引:2,他引:0
Nuclear DNA helicase II (NDH II) is the bovine homolog of human RNA helicase A. The aim of this study was to compare NDH II
localization between somatic cells (bovine embryonal fibroblasts) and female germ cells (oocytes), with the main focus on
the dynamic changes in the redistribution of NDH II during the growth phase of the bovine oocytes. The fine granular staining
of NDH II was spread in the whole nucleoplasm of fibroblasts, excluding the reticulated nucleoli. In contrast, the large reticulated
nucleoli of the growing oocytes isolated from early antral follicles exhibited strong positivity for NDH II together with
the immunostaining signals of upstream binding factor (UBF) and RNA polymerase I subunit (PAF53), documenting the high synthetic
activity of these nucleoli. At the time of termination of oocyte growth, NDH II was preferentially located at the nucleolar
periphery together with proteins of fibrillar centres. In fully grown oocytes, NDH II was still present in the thin periphery
shell around the compact nucleolar core. The semiquantitative RT-PCR revealed that the average signal of NDH II mRNA in fully
grown oocytes was only at 40% level in comparison with growing oocytes. Western blot analysis further confirmed that a 140 kD
NDH II protein was abundant in growing oocytes, while the signal was substantially weaker in fully grown oocytes. The significant
decrease in NDH II gene expression and in NDH II mRNA translation correlates with a termination of the oocyte growth. Altogether,
the results demonstrate that NDH II expression parallels the activity of ribosomal RNA biosynthesis in the bovine growing
oocytes. 相似文献
52.
Purified bovine heart cytochrome c oxidase (CcO) has been extracted from aqueous solution into hexane in the presence of phospholipids and calcium ions. In extracts, CcO is in the so-called "slow" form and probably situated in reverse micelles. At low water:phospholipid molar ratios, electron transfer from reduced heme a and Cu(A) to the catalytic center is inhibited and both heme a3 and Cu(B) remain in the oxidized state. The rate of binding of cyanide to heme a3 in this oxidized catalytic center is, however, dependent on the redox state of heme a and Cu(A). When heme a and Cu(A) are reduced, the rate is increased 20-fold compared to the rate when these two centers are oxidized. The enhanced rate of binding of cyanide to heme a3 is explained by the destabilization of an intrinsic ligand, located at the catalytic site, that is triggered by the reduction of heme a and Cu(A). 相似文献
53.
Oxovanadium(IV) complexes of the polyalcohols sorbitol, galactitol, and mannitol, of stoichiometry Na(2)[VO(L)(2)].H(2)O, were obtained from aqueous alkaline solutions. They were characterized by elemental analysis, infrared and UV-vis spectroscopies, thermoanalytical (thermogravimetric and differential thermal analysis) data, and magnetic susceptibility measurements. The biological activities of the complexes on the proliferation, differentiation, and glucose consumption were tested on osteoblast-like cells (MC3T3E1 osteoblastic mouse calvaria-derived cells and UMR106 rat osteosarcoma-derived cells) in culture. The three complexes exerted a biphasic effect on cell proliferation, being slight stimulating agents at low concentrations and inhibitory in the range of 25-100 microM. All the complexes inhibited cell differentiation in tumor osteoblasts. Their effects on glucose consumption were also discussed. The free ligands did not show any effect on the studied biological parameters. 相似文献
54.
55.
56.
Krishnamoorthy G Sehgal PK Mandal AB Sadulla S 《Journal of enzyme inhibition and medicinal chemistry》2012,27(3):451-457
We report the detailed studies on the inhibitory effect of tannic acid (TA) on Clostridium histolyticum collagenase (ChC) activity against degradation of extracellular matrix component of collagen. The TA treated collagen exhibited 64% resistance against collagenolytic hydrolysis by ChC, whereas direct interaction of TA with ChC exhibited 99% inhibition against degradation of collagen and the inhibition was found to be concentration dependant. The kinetic inhibition of ChC has been deduced from the extent of hydrolysis of N-[3-(2-furyl) acryloyl]-Leu-Gly-Pro-Ala (FALGPA). This data provides a selective competitive mode of inhibition on ChC activity seems to be influenced strongly by the nature and structure of TA. TA showed inhibitor activity against the ChC by molecular docking method. This result demonstrated that TA containing digalloyl radical possess the ability to inhibit the ChC. The inhibition of ChC in gaining new insight into the mechanism of stabilization of collagen by TA is discussed. 相似文献
57.
Ali NA Gaughan AA Orosz CG Baran CP McMaken S Wang Y Eubank TD Hunter M Lichtenberger FJ Flavahan NA Lawler J Marsh CB 《PloS one》2008,3(4):e1914
Latency Associated Peptide (LAP) binds TGF-beta1, forming a latent complex. Currently, LAP is presumed to function only as a sequestering agent for active TGF-beta1. Previous work shows that LAP can induce epithelial cell migration, but effects on leukocytes have not been reported. Because of the multiplicity of immunologic processes in which TGF-beta1 plays a role, we hypothesized that LAP could function independently to modulate immune responses. In separate experiments we found that LAP promoted chemotaxis of human monocytes and blocked inflammation in vivo in a murine model of the delayed-type hypersensitivity response (DTHR). These effects did not involve TGF-beta1 activity. Further studies revealed that disruption of specific LAP-thrombospondin-1 (TSP-1) interactions prevented LAP-induced responses. The effect of LAP on DTH inhibition depended on IL-10. These data support a novel role for LAP in regulating monocyte trafficking and immune modulation. 相似文献
58.
We have developed a model of the tetrameric ryanodine receptor--the calcium channel of the sarcoplasmic reticulum. The model accurately describes published experimental data on channel activity at various concentrations of Ca2+, caffeine and quercetin. The proposed mechanisms involve allosteric regulation of Ca2+ affinity by both caffeine and quercetin, and the existence of two independent, A- and I-gates controlled by Ca2+ binding to an activating and an inhibitory module of the receptor. There are four different configurations of the receptor that affect ligand binding to the activation module, but not to the inhibition module. Consequently, there are four kinetic modes for the A-gate and one mode for the I-gate. At a certain moment, the receptor can be in any of the four possible conformations with equal probability. By fitting the data we are able to derive ligand affinities and Hill coefficients, to describe the observation that quercetin is an activating agent stronger than caffeine, and that caffeine and quercetin activate the channel at very low Ca2+ concentration (approximately 10(-11) M). We predict that the activation regime at saturating caffeine or quercetin should present four distinct regions at increasing Ca2+, corresponding to the four different gating modes. Another interesting prediction is the enlargement of the activity domain toward higher Ca2+ concentrations in the presence of caffeine or quercetin. 相似文献
59.
60.
Maria C. Apella Roxana Totaro Enrique J. Baran 《Biological trace element research》1993,37(2-3):293-299
The superoxide-dismutase-like activity of a series of divalent metal saccharinates of general stoichiometry [MII(Sac)2(H2O)4]·2H2O (with MII=Mn,Fe,Co,Ni,Cu,Zn) has been investigated using the nitroblue tetrazolium O
2
−
reduction assay. The results show that all these complexes possess the capability to dismutate the superoxide anion generated
in the xanthine/xanthine oxidase system. Interestingly, the greatest activity is shown by the corresponding copper complex.
The results are discussed and compared with those obtained for native superoxide dismutase, which was tested under the same
experimental conditions.
Dedicated to Prof. Pedro J. Aymonino on the occasion of his 65th birthday. 相似文献