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91.
Nishiyama T Kobori T Arai K Ogura K Ohnuma T Ishii K Hayashi K Hiratsuka A 《Archives of biochemistry and biophysics》2006,454(1):72-79
Glucuronidation is a major metabolic pathway in the biotransformation of many xenobiotics and endogeneous compounds. There have been many studies on the formation of O-, N- or S-glucuronides and identification of the UDP-glucuronosyltransferase (UGT) isoforms responsible for the formation of these glucuronides. However, there is no information available on which UGT isoform(s) catalyzes C-glucuronidation. In the present study, 16 human UGTs (UGTs 1A1, 1A3, 1A4, 1A5, 1A6, 1A7, 1A8, 1A9, 1A10, 2B4, 2B7, 2B10, 2B11, 2B15, 2B17 and 2B28) were cloned and expressed in baculovirus-infected insect cells and investigated to determine their C-glucuronidating activity toward phenylbutazone (PB). Among the UGT isoforms investigated, only UGT1A9 catalyzed PB C-glucuronidation. Human liver and kidney microsomes, which are well known to express UGT1A9, had C-glucuronidating activity toward PB. However, the jejunum, which did not express UGT1A9, had no C-glucuronidating activity. These results demonstrate for the first time that PB C-glucuronidation is catalyzed by only UGT1A9. 相似文献
92.
Chemical lesions of the brain stem region containing glycinergic omnipause neurons (OPNs) cause saccade slowing with no change
in latency. To explore the mechanisms responsible for this deficit, simulation studies were performed with a conductance-based
model of premotor excitatory burst neurons (EBNs) that incorporated multiple membrane channels, including the T-type calcium
channel. The peak speed of a normal saccade was determined by the T- and NMDA currents in EBNs after the OPNs shut off. After
OPN lesions, the model made slow saccades, because the EBN activity was lower than normal due to a reduced T-current (caused
by the loss of hyperpolarization), and a reduced NMDA current (caused by a reduced glycine concentration around the receptors).
Thus, we propose that two biophysical mechanisms are responsible for saccade slowing after OPN lesions: reduced T-current
and reduced NMDA current, both of which are caused by the loss of glycine from OPNs.
Action Editor: Karen Sigvardt 相似文献
93.
Hirofumi Sakamoto Tomomi Kuboi Takahiko Nagakura Sayako Hayashi Fumio Hoshi Kenichiro Mutoh Kiyotaka Watanabe Koichi Orino 《Biometals》2009,22(5):793-802
Ferritin-binding proteins (FBPs) such as anti-ferritin antibody, α-2-macroglobulin, apolipoprotein B are expected to interact
with circulating ferritin to eliminate it from circulation. However, we found that feline serum more strongly inhibits the
detection of canine liver ferritin by immunoassay than its apoferritin; putative FBPs probably conceal ferritin epitopes detected
by anti-ferritin antibodies. After complex formation between affinity-purified FBPs and canine liver ferritin, co-immunoprecipitates
of the complex by anti-bovine spleen ferritin antibody were found to contain autoantibodies (IgG, IgM, and IgA) to ferritin
by immunoblot analysis with antibodies specific for feline IgG, IgM, and IgA. On the other hand, affinity-purified samples
did not show any inhibitory effect in the ferritin immunoassay. This result shows that feline serum has another FBP, which
inhibits ferritin immunoassays, but not anti-ferritin autoantibody. A feline FBP was partially purified from feline serum
by (NH4)2SO4 fractionation (33–50%), gel filtration chromatography, and anion exchange chromatography. After binding of the partially
purified sample with canine liver ferritin coupled-Sepharose gel, the FBP was separated and purified from complexes formed
in a native-PAGE gel. SDS–PAGE analysis showed that the purified FBP is a homomultimer composed of 31 kDa monomeric subunits
connected by intermolecular disulfide bonds. Detection of feline liver ferritin by immunoassay was inhibited by FBP in a dose-dependent
manner. The purified protein molecules appeared to be conglomerate of pentraxin-like molecules by its electron micrographic
appearance. These results demonstrate that feline serum contains a novel FBP as inhibitory factor of ferritin immunoassay
with different molecular properties from those of other mammalian FBPs, in addition to auto-antibodies (IgG, IgM, and IgA)
to ferritin. 相似文献
94.
95.
Takuya Sugahara Keiko Ueno-Shuto Eriko Watanabe Kenichiro Kitamura Ai Mizuno Mary Ann Suico 《Experimental cell research》2009,315(19):3294-24
Epithelial sodium channel (ENaC) is a heteromultimeric Na+ channel at the apical membrane in the kidney, colon, and lung. Because ENaC plays a crucial role in regulating Na+ absorption and extracellular fluid volume, its dysregulation causes severe phenotypes including hypertension, hypokalemia, and airway obstruction. Despite the importance of ENaC, its protein quality control mechanism remains less established. Here we firstly show the role of calreticulin (CRT), a lectin-like molecular chaperone in the endoplasmic reticulum (ER), on the regulation of ENaC. Overexpression and knockdown analyses clearly indicated that CRT positively affects the expression of each ENaC subunit (α, β and γ). CRT overexpression also up-regulated the cell surface expression of α-, β- and γ-ENaC. Moreover, we found that CRT directly interacts with each ENaC subunit. Although CRT knockdown did not affect the de novo synthesis of ENaC subunits, CRT overexpression decreased α-, β- and γ-ENaC expression in the detergent (RIPA)-insoluble fraction, suggesting that CRT enhanced the solubility of ENaC subunits. Consistent with the increased intracellular and cell surface expression of ENaC subunits, increased channel activity of ENaC was also observed upon overexpression of CRT. Our study thus identifies CRT as an ER chaperone that regulates ENaC expression and function. 相似文献
96.
Ayumi Ikeda Esteban C. Gabazza John Morser Ichiro Imoto Mikihito Kuroda Corina N. D'Alessandro-Gabazza Kenichiro Hara Daniel Boveda Ruiz Paloma Gil Bernabe Masaki Katsurahara Masaaki Toda Yoshinao Kobayashi Yutaka Yano Yasuhiro Sumida Koji Suzuki Osamu Taguchi Yoshiyuki Takei 《Helicobacter》2009,14(2):147-155
Thrombin-activatable fibrinolysis inhibitor (TAFI) plays a role in the regulation of coagulation and inflammation. In addition to inhibiting the fibrinolytic system, TAFI may also regulate the bradykinin and complement systems. We hypothesized that TAFI also plays a role in defense mechanisms of the gastric mucosa during Helicobacter pylori infection. This study comprised 65 patients with gastroduodenal disorders: 41 patients with H. pylori infection, 13 without, and 11 patients with cured H. pylori infection. The gastric intramucosal concentrations of TAFI were measured by enzyme immunoassay. The gastric levels of TAFI and plasminogen activator inhibitor-1 were significantly increased in patients with H. pylori compared to those without infection or cured H. pylori . The presence of TAFI was detected in gastric mucosal epithelial cells. The concentration of TAFI was correlated with the degree of gastric mucosal atrophy, inflammation, and disease activity. These results show that TAFI is present in the gastric mucosa and that it may play a role in the pathogenesis of H. pylori infection-associated gastroduodenal disorders. 相似文献
97.
Shen Z Crotti TN McHugh KP Matsuzaki K Gravallese EM Bierbaum BE Goldring SR 《Arthritis research & therapy》2006,8(3):R70-10
Prosthetic wear debris-induced peri-implant osteolysis is a major cause of aseptic loosening after total joint replacement.
In this condition, wear particles released from the implant components induce a granulomatous inflammatory reaction at the
interface between implant and adjacent bone, leading to progressive bone resorption and loss of fixation. The present study
was undertaken to characterize definitively the phenotype of osteoclast-like cells associated with regions of peri-implant
focal bone resorption and to compare the phenotypic features of these cells with those of mononucleated and multinucleated
cells associated with polyethylene wear particles. Peri-implant tissues were obtained from patients undergoing hip revision
surgery for aseptic loosening after total joint replacement. Cells were examined for the expression of several markers associated
with the osteoclast phenotype using immunohistochemistry, histochemistry, and/or in situ hybridization. CD68 protein, a marker expressed by multiple macrophage lineage cell types, was detected in mononucleated
and multinucleated cells associated with polyethylene particles and the bone surface. Cathepsin K and tartrate-resistant acid
phosphatase were expressed highly in both mononucleated and multinucleated cells associated with the bone surface. Levels
of expression were much lower in cells associated with polyethylene particles. High levels of β3 integrin protein were detected in cells in contact with bone. Multinucleated cells associated with polyethylene particles
exhibited faint positive staining. Calcitonin receptor mRNA expression was detected solely in multinucleated cells present
in resorption lacunae on the bone surface and was absent in cells associated with polyethylene particles. Our findings provide
further evidence that cells expressing the full repertoire of osteoclast phenotypic markers are involved in the pathogenesis
of peri-implant osteolysis after total joint replacement. They also demonstrate that foreign body giant cells, although believed
to be phenotypically and functionally distinct from osteoclasts, express many osteoclast-associated genes and gene products.
However, the levels and patterns of expression of these genes in the two cell types differ. We speculate that, in addition
to the role of cytokines and growth factors, the substrate with which these cells interact plays a critical role in their
differential phenotypic and functional properties. 相似文献
98.
Study on immunocapture-chemiluminescence assay of lipase activity in a biological sample. 总被引:1,自引:0,他引:1
Tomoko Ichibangase Chie Hamabe Yoshihito Ohba Naoya Kishikawa Kenichiro Nakashima Yuzo Kayamori Dongchon Kang Naotaka Hamasaki Naotaka Kuroda 《Luminescence》2006,21(1):62-66
A new approach for the determination of lipase (triacylglycerol lipase, EC.3.1.1.3) activity in a biological sample was investigated by combining an immunocapture technique with a chemiluminescence (CL) assay method in order to eliminate interference with CL detection. The proposed method consists of an immunocapture step to trap lipase and a subsequent step for CL detection of the activity of the captured lipase. The CL detection is based on the luminol-hydrogen peroxide (H(2)O(2))-horseradish peroxidase (HRP) reaction and utilizes a proenhancer substrate [a lauric acid ester of 2-(4-hydroxyphenyl)-4,5-diphenylimidazole (HDI)] which liberates an active enhancer, HDI, by enzymatic hydrolysis. A polyclonal antibody prepared with porcine pancreas lipase was used for the immunocapture. The proposed immunocapture-CL method effectively eliminated the interference with the CL reaction from biological components and enabled the determination of spiked porcine pancreas lipase activity in serum samples in the range 0.41-1.1 U(HDI) (1 U(HDI) corresponds to the amount which liberates 1 pmol HDI/min at 37 degrees C from the substrate). The method was further applied to the assay of the activity for human pancreas lipase in serum and the results showed good correlation (r = 0.871) with those by the conventional colorimetric method. 相似文献
99.
Shimatani K 《Journal of molecular evolution》1999,49(6):810-813
Nucleotide diversity may be decreased when a different DNA sequence type appears in a population. This undesirable property
in a genetic diversity index is demonstrated by mathematical examples. The possibility of this phenomenon in natural populations
is briefly discussed.
Received: 21 June 1999 / Accepted: 27 July 1999 相似文献
100.
It has previously been demonstrated that the addition of cork tissue to cell suspension cultures of Sophora flavescens stimulates the production of sophoraflavanone G, most of which has been recovered from the added cork tissue. In the present study, it was found that two precursors of sophoraflavanone G, 8-prenylnaringenin (sophoraflavanone B) and leachianone G, both of which have never been detected either in cultured cells or in the original plants, also accumulated in the added cork tissue. Thirteen minor flavonoids including three prenylated flavonoids, in addition to 8-prenylnaringenin and leachianone G, were isolated from the cork tissue co-incubated with S. flavescens cells. The new compounds flavescenones A, B and C, were determined to be (3R)-5, 7, 2'-trihydroxy-6-gamma, gamma-dimethylallyl-4', 5'-methylenedioxyisoflavanone; 5, 7, 2'-trihydroxy-6-gamma, gamma-dimethylallyl-4', 5'-methylenedioxyisoflavone and 2-[2',4'-dihydroxy-3'-(gamma-hydroxymethyl-gamma-methylallyl)phenyl]-5,6-methylenedioxybenzofuran, respectively, by means of spectroscopic analyses that included 2D-NMR techniques. 相似文献