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1.
In the adult dog liver cytosol we identified four glutathione S-transferase (GST) subunits, Yd1 (Mr 26,000), Yd2 (Mr 27,000), Yd3 (Mr 28,000), and Ydf (Mr 27,400), and purified GST forms comprising Yd1, Yd2, and Yd3, to apparent homogeneity. Unlike rat transferases the enzyme activity toward 1,2-dichloro-4-nitrobenzene (DCNB) was not retained on the affinity column. Thus the DCNB-active enzyme, GST YdfYdf, from the flow-through fraction of the affinity column was also purified to homogeneity by gel filtration, DE52 chromatography, chromatofocusing, and hydroxylapatite column chromatography. Immunoblot analysis of dog GSTs revealed that the subunits Yd1, Yd2, and Yd3 belong to the pi, alpha, and mu class, respectively. On the contrary, Ydf had no reactivity with antibodies raised against any of the three classes of GST. Each subunit, Yd1, Yd2, Yd3, and Ydf, was distinguishable by its own retention time on reverse-phase high performance liquid chromatography. N-terminal amino acid sequences of the dog GSTS Yd1Yd1 and Yd3Yd3 revealed a high degree of homology to the pi and mu class transferases from rat, human, and mouse, respectively, while the N terminus of Yd2Yd2 is blocked. N-terminal amino acid sequences of GST YdfYdf showed no homology to any of the three classes of GST. The most significant property noted of GST YdfYdf is the high specific activity toward DCNB, exceeding by 1 order of magnitude the corresponding values for the known mu class GSTs. The present results strongly suggest that dog GST YdfYdf is a unique enzyme distinct from the hitherto characterized GST isozymes.  相似文献   
2.
N-Acetyl-L-glutamate has been examined with regard to its ability to activate carbamoyl phosphate synthetase I (EC 6.3.4.16). Substance(s) inhibitory to carbamoyl phosphate synthetase, present even in the partially purified preparation of rat liver extracts, interfered with the measurement of acetylglutamate. In the experiments using chelating agents, metals were apparently involved in this inhibition. When the partially purified preparation of liver extract was placed on a Chelex 100 column, the inhibitor was eliminated and accurate measurements of acetylglutamate content could be made. Evidence supporting the validity of this improved method is given. A significant difference was observed between acetylglutamate levels determined by the present method and by the one using aminoacylase I (N-acylamino acid amidohydrolase, EC 3.5.1.14) to hydrolyze acetylglutamate followed by assay of the glutamate generated. We searched for the presence of glutamate derivatives other than acetylglutamate. When impure tissue preparations containing acetylglutamate were treated with a commercial preparation of aminoacylase, there was an excess amount of glutamate apparently derived from compounds other than acetylglutamate. This can lead to an overestimation of the tissue levels of acetylglutamate.  相似文献   
3.
This study monitored deposition and decomposition of cattle dung in a grazed young Chamaecyparis obtusa (an evergreen conifer) plantation in southwestern Japan, as a part of exploring the impacts of livestock in the forest grazing system. Animals defecated 10–19 times hd−1 day−1, producing feces of 2.2–3.5 kg DM and 33–73 g N per animal per day. The DM and N concentrations of feces ranged from 157–207 g DM kg−1 and 14.8−23.1 g (kg DM)−1, respectively. Occurrence of defecation was spatially heterogeneous, with feces being concentrated mainly on areas for resting (forest roads, ridges and valleys) and moving (forest roads and along fence lines). Decomposition of dung pats was considerably slow, showing the rates of 1.37–3.05 mg DM (g DM)−1 day−1 as DM loss. Decomposition was further slower on the basis of N release, 0.51–1.63 mg N (g N)−1 day−1, resulting in steadily increased N concentrations of dung pats with time after deposition. The results show that introduction of livestock into a forest (i.e., forest grazing) may limit nutrient availability to plants, by redistributing nutrients into areas with no vegetation (bare land and streams) and by establishing a large N pool as feces due to an imbalance between deposition and slow release, though further studies are necessary for investigating the occurrence of slow dung decomposition in other forest situations.  相似文献   
4.
5.
In vivo biologic effects of the polymorphonuclear leukocyte-inhibitory factor (PIF) of Bordetella pertussis were tested by using two experimentally induced inflammatory processes in mice. The intravenous injection of a partially purified extract from phase I bacteria strongly inhibited the glycogen-induced peritoneal infiltration of polymorphonuclear leukocytes (PMN) and the Arthus reactions, whereas little inhibitory activity was found in the extract from phase III bacteria. The activity was localized in the outer membrane of phase I bacteria, as was the in vitro PIF activity, and the two activities gave the same behavior in DEAE-cellulose chromatography. Therefore the observed suppression of inflammatory processes in mice is probably due to the inhibitory action of PIF on the function of PMN in vivo.  相似文献   
6.
To investigate the immunosuppressive effects of glutarimide antibiotics including a new antibiotic named epiderstatin, we tested these antibiotics for inhibition of the blastogenesis of mouse spleen cells induced by mitogen stimulation (concanavalin A or lipopolysaccharide). The inhibitory activity was measured by colorimetric MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay. Among the glutarimide antibiotics tested, epiderstatin and acetoxycycloheximide especially strongly inhibited the blastogenesis of mouse spleen cells induced by concanavalin A and lipopolysaccharide, however, selectivity between T and B lymphocytes was not observed.  相似文献   
7.
Endogenous danger signals released from necrotic cells contribute to retinal inflammation. We have now investigated the effects of necrotic cell extracts prepared from ARPE-19 human retinal pigment epithelial cells (ANCE) on the release of proinflammatory cytokines and chemokines by healthy ARPE-19 cells. ANCE were prepared by subjection of ARPE-19 cells to freeze-thaw cycles. The release of various cytokines and chemokines from ARPE-19 cells was measured with a multiplex assay system or enzyme-linked immunosorbent assays. The expression of interleukin (IL)–1α and the phosphorylation and degradation of the endogenous nuclear factor–κB (NF-κB) inhibitor IκB-α were examined by immunoblot analysis. Among the various cytokines and chemokines examined, we found that ANCE markedly stimulated the release of the proinflammatory cytokine IL-6 and the chemokines IL-8 and monocyte chemoattractant protein (MCP)–1 by ARPE-19 cells. ANCE-induced IL-6, IL-8, and MCP-1 release was inhibited by IL-1 receptor antagonist and by an IKK2 inhibitor (a blocker of NF-κB signaling) in a concentration-dependent manner, but was not affected by a pan-caspase inhibitor (Z-VAD-FMK). Recombinant IL-1α also induced the secretion of IL-6, IL-8, and MCP-1 from ARPE-19 cells, and IL-1α was detected in ANCE. Furthermore, ANCE induced the phosphorylation and degradation of IκB-α in ARPE-19 cells. Our findings thus suggest that IL-1α is an important danger signal that is released from necrotic retinal pigment epithelial cells and triggers proinflammatory cytokine and chemokine secretion from intact cells in a manner dependent on NF-κB signaling. IL-1α is therefore a potential therapeutic target for amelioration of sterile inflammation in the retina.  相似文献   
8.

Purpose

To determine whether the width of the retinal artery (RA) trajectory was associated with the presence of a macular hole (MH).

Methods

A retrospective cross sectional case-control study was performed. The fundus photographs were rotated 90 degrees, and the coordinates of the best fit curve of the RA trajectory were determined automatically based on these plots using the ImageJ program. The converted coordinates were fit to a second degree polynomial (ax2/100 + bx + c) equation. The width and steepness of the RA trajectory, “a”, of the eyes with a MH eye were compared to that of the fellow eyes.

Results

One hundred and ten eyes of 55 consecutive patients (30 women) with a unilateral MH and healthy fellow eyes were analyzed. The mean age was 64.9 years (range 47-81 years). The constant ‘a’ was significantly smaller in eyes with a MH than that of the fellow eyes (0.379 ± 0.094 vs 0.416 ± 0.121, P = 0.001, paired t test), indicating that the RA trajectory was wider in the MH eyes than in the fellow eyes. There was a significant correlation between the axial length and ‘a’ of the RA trajectory in the MH eyes (R = 0.273, P = 0.044) and in the fellow eyes (R = 0.356, P = 0.008; Spearman’s rank correlation coefficient).

Conclusions

Because eyes with a MH have a significantly wider and flatter RA trajectory, there may be greater traction on the fovea which is located between the RA arches. The causative role of this finding is still unclear.  相似文献   
9.
10.
Metabolism of 32-hydroxy-24,25-dihydrolanosterol (lanost-8-ene-3 beta,32-diol), a posturated intermediate of the 14 alpha-demethylation (removal of C-32) of 24,25-dihydrolanosterol (lanost-8-en-3 beta-ol), by a reconstituted system consisting of yeast cytochrome P-450 which catalyzes lanosterol 14 alpha-demethylation (cytochrome P-45014DM) (Yoshida, Y., and Aoyama, Y. (1984) J. Biol. Chem. 259, 1655-1660 and Aoyama, Y., Yoshida, Y., and Sato, R. (1984) J. Biol. Chem. 259, 1661-1666) and NADPH-cytochrome P-450 reductase was studied. The reconstituted system converted both 32-hydroxy-24,25-dihydrolanosterol and 24,25-dihydrolanosterol to 4,4-dimethyl-5 alpha-cholesta-8,14-dien-3 beta-ol, the 14 alpha-demethylated product of the latter. The metabolism of these compounds was inhibited by a low concentration of ketoconazole which is a potent cytochrome P-45014DM inhibitor. Affinity of cytochrome P-45014DM for 32-hydroxy-24,25-dihydrolanosterol was about 20 times higher than for 24,25-dihydrolanosterol and the cytochrome metabolized the former about 4 times faster than the latter under the experimental conditions. Spectral analysis suggested that the 32-hydroxyl group of 32-hydroxy-24,25-dihydrolanosterol interacted with the heme iron of the oxidized cytochrome and this interaction might support the high affinity of this compound for the cytochrome. These lines of evidence indicate that 32-hydroxy-24,25-dihydrolanosterol is the intermediate of the 14 alpha-demethylation of 24,25-dihydrolanosterol by cytochrome P-45014DM. It is also clear that the cytochrome catalyzes further metabolism of the 32-hydroxylated intermediate to the 14 alpha-demethylated product with higher efficiency than the 32-hydroxylation of the substrate. Cytochrome P-45014DM is thus classified as lanosterol C14-C32 lyase.  相似文献   
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