首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   408篇
  免费   36篇
  2022年   2篇
  2021年   5篇
  2020年   8篇
  2019年   2篇
  2018年   7篇
  2017年   2篇
  2016年   9篇
  2015年   20篇
  2014年   10篇
  2013年   16篇
  2012年   24篇
  2011年   21篇
  2010年   14篇
  2009年   16篇
  2008年   22篇
  2007年   15篇
  2006年   18篇
  2005年   18篇
  2004年   23篇
  2003年   29篇
  2002年   15篇
  2001年   16篇
  2000年   18篇
  1999年   12篇
  1998年   8篇
  1997年   9篇
  1996年   9篇
  1994年   4篇
  1993年   6篇
  1992年   6篇
  1991年   3篇
  1990年   3篇
  1989年   9篇
  1988年   6篇
  1987年   5篇
  1986年   3篇
  1985年   3篇
  1984年   3篇
  1983年   2篇
  1982年   4篇
  1981年   2篇
  1980年   2篇
  1976年   1篇
  1975年   1篇
  1974年   3篇
  1973年   1篇
  1971年   2篇
  1969年   1篇
  1968年   1篇
  1960年   1篇
排序方式: 共有444条查询结果,搜索用时 15 毫秒
111.
Indoleamine 2,3-dioxygenase activity in the supernatant fractions (30,000g, 30 min) from various tissues of mice increased almost linearly after a single intraperitoneal administration of bacterial lipopolysaccharide (5 to 20 μg/mouse). The most prominent effect was observed in the lung, where both specific and total enzyme activities increased 40 to 80-fold during the first 24 h. Significant (10- to 20-fold) stimulation was also observed in the seminal vesicle, coagulating gland, colon, and caecum, and severalfold in the trachea, stomach, heart, small intestine, and spleen. Lipid A fraction, the biologically active unit in the lipopolysaccharide complex, was as active as the lipopolysaccharide preparations from either Escherichia coli or Salmonella S and R mutant strains, whereas the polysaccharide fraction was inactive under identical experimental conditions. When mice were pretreated with a series of daily injections of bacterial lipopolysaccharide, enzyme induction was no longer evident, indicating that tolerance to this agent had developed and that enzyme induction was caused by lipopolysaccharide but not by possible contaminants in the preparations. The enzyme activities from normal and lipopolysaccharide-treated mice were exclusively found in the soluble fractions of mouse lung homogenates. Other enzyme activities in the lung such as lysosomal (acid phosphatase), microsomal (prostaglandin cyclooxygenase), mitochondrial (monoamine oxidase and superoxide dismutase), and soluble enzyme activities (lipooxygenase and superoxide dismutase) were not significantly altered by this treatment. This increase in the enzyme activity with the lipopolysaccharide treatment was abolished with a simultaneous administration of cycloheximide or actinomycin D, and an immunological analysis with antibody for mouse enzyme (rabbit IgG) demonstrated that the observed increment of the enzyme activity was essentially due to an increase in the enzyme protein.  相似文献   
112.
Summary The role of various iron chelators on the multiplication of mouse hybridoma cells in an albumin-free, transferrin-deficient defined medium was investigated. Fe(III)-dihydroxyethylglycine, Fe(III)-glycylglycine, Fe(III)-ethylenediamine-N,N′-dipropionic acid, or Fe(III)-iminodiacetic acid supported the excellent growth of the cells. In addition, the growth of the iron-starved cells, which had been preincubated in a protein-, iron- and chelator-free defined medium, restored rapidly when the medium was supplemented with holotransfeerrin, ferric iron, and chelator compared to that when supplemented with holotransferin, but without iron and chelator. The results suggest that such chelators modulate a progression of transferrn cycle in the presence of transferin and ferric iron. An alternative explantation is that there is a decrease in generation of iron-catalyzed free radicals.  相似文献   
113.
Fucosylated haptoglobin (Fuc-Hpt) and Mac-2 binding protein (Mac-2 bp) are identified as cancer biomarkers, based on the results from a glyco-proteomic analysis. Recently, we reported that these glyco-biomarkers were associated with liver fibrosis and/or ballooning hepatocytes in patients with nonalcoholic fatty liver disease (NAFLD). We evaluated the ability of these glycoproteins to estimate liver fibrosis in 317 patients with chronic hepatitis C. We measured the serum Fuc-Hpt and Mac-2 bp levels using a lectin-antibody ELISA and ELISA, respectively. The serum levels of both Fuc-Hpt and Mac-2 bp increased with the progression of liver fibrosis. The multivariate analysis revealed that Mac-2 bp was an independent factor associated with moderate liver fibrosis (F ≥ 2). In contrast, Fuc-Hpt was an independent factor associated with advanced liver fibrosis (F ≥ 3). In terms of evaluating liver fibrosis, the serum levels of these glycomarkers were correlated with well-known liver fibrosis indexes, such as the aspartate aminotransferase to platelet ratio index (APRI) and Fibrosis-4 (FIB4) index. An assay that combined the APRI or FIB4 index and the Fuc-Hpt or Mac-2 bp levels increased the AUC value for diagnosing hepatic fibrosis. Interestingly, the cumulative incidence of hepatocellular carcinoma (HCC) was significantly higher in the patients with elevated serum levels of Fuc-Hpt and Mac-2 bp. In conclusion, both Fuc-Hpt and Mac-2 bp could be useful glyco-biomarkers of liver fibrosis and predictors of HCC in patients with chronic hepatitis C.  相似文献   
114.
115.
Vital statistics on the breeding through successive generations were presented for the cynomolgus monkey colony of NIH, Tokyo. The results of this retrospective survey clearly demonstrated the third (F2) and the fourth (F3) generations could be bred and reared successfully by the indoor caged-breeding system in which either individual timed-mating or group mating procedure was adopted. Several important and difficult problems involved in the production of successive generations of the cynomolgus monkey by our breeding system were discussed from the standpoint of laboratory animal science.  相似文献   
116.
Summary We describe a genetic polymorphism of human lymphocyte cytosol major polypeptide with mol. wt. 64,000, detected in peripheral blood lymphocytes by high resolution two-dimensional electrophoresis. Three different electrophoretic types (1-1, 2-1, 2-2) of the polypeptide have been identified. Family and population studies indicate that the three phenotypes of the polypeptide are determined by two common alleles at a single autosomal locus. The polypeptide occurs in the cytosol and is predominent in peripheral blood lymphocytes, B-lymphoblastoid cells, T-lymphoblastoid cells, lymph node, and spleen. The polypeptide has not been detected in HeLa cells, fibroblasts, erythrocytes, serum, and cerebrum. Traces of the polypeptide exist in liver, kidney, and skeletal muscle. It is proposed that the polypeptide and its locus be temporarily designated lymphocyte cytosol 64K polypeptide (LC64K polypeptide) andLC64P, respectively. In a Japanese population, the gene frequencies ofLC64P 1 andLC64P 2 were 0.936 and 0.064, respectively. The data suggest thatLC64P is a new locus, product of which shows genetic polymorphism and is associated with the function and/or the structure of lymphocytes.  相似文献   
117.
The circadian rhythm of gastric content, serum alkaline phosphatase (alk.P.), serum lipids, body weight (wt), relative (rel.) liver wt, cellular structures (by light- and electron-microscopy), mitotic activity of hepatocytes, glycogen content, protein and lipids in liver was studied in 180 male Sprague-Dawley rats orally treated at 0830-1030 with 50 mg/kg phenobarbital (PB) for 7 days. Thereafter, five PB-treated males and five controls each were studied at 4-hr intervals at 0600, 1000, 1400, 1800, 2200 and 0200 on 3 consecutive days. The lighting schedule in the colony was 12:12 = light/dark (light from 0600 to 1800). Following the rhythm of gastric emptying, the rel. liver wt showed a clear circadian rhythm with a peak at 0800. The rel. liver wt was raised in PB-treated rats at all times of the day. The circadian rhythm of cellular structures was closely related to the hepatic glycogen content which exhibited a clear rhythm with the peak also at 0800, but lowered values were found in PB-treated rats. The mitotic activity of hepatocytes was significantly increased in PB-treated rats but displayed the same circadian rhythm as controls with peaks at noon and troughs at midnight. The well-known hypertrophy of the smooth endoplasmic reticulum in PB-treated rats was not found at 0600, but was fully developed at 1400 and 2200. PB-treatment increased significantly the liver content of cholesterol, triglycerides and phospholipids. Liver cholesterol showed a clear circadian rhythm with peaks at 1800. No rhythm of liver protein, triglycerides and phospholipids was observed. In serum, levels of cholesterol were significantly elevated, those of triglycerides and alk.P. significantly lowered, while those of phospholipids were not affected by the treatment. The three serum lipids, alk.P. and beta-lipoprotein exhibited a clear circadian rhythm, while serum glucose and non-esterified fatty acids did not.  相似文献   
118.
119.
Interstitial cells of Cajal in the myenteric plexus region (ICC-MyP) form a network and generate basal pacemaking electrical activity. This morphological feature leads us to believe that these cells may be essential for the coordinating actions of gastrointestinal (GI) motility. We aim to propose a new method for functional assessment of ICC electrical activity and its network. Field potentials in a 1 mm2 region were simultaneously measured using an 8 × 8 microelectrode array (MEA) with a polar distance of 150 μm. The extracellular solution contained nifedipine and tetrodotoxin (TTX) to suppress activities of smooth muscle cells and neurons, respectively. We compared spatial electrical activities between ileal muscle preparations from wild-type (WT) and W/Wv mice. In spatio-temporal analyses, basal electrical activities were well synchronized with a propagation delay in WT, while those in W/Wv were small in amplitude and irregular in occurrence. The power spectrum in WT had a prominent peak corresponding to the frequency of ICC-MyP pacemaker activity, while that of W/Wv lacked it. Consequently, the ratio of the spectral power in 9.4–27.0 cpm was significantly larger in WT than in W/Wv. In conclusion, MEA measurements demonstrated that the network-forming ICC-MyP not only generates but also coordinates basal electrical activities. Disorders of GI motility based on morphological and functional impairments of ICC network with the range of several hundreds of micrometers, could be uncovered in future extensive studies.  相似文献   
120.
Monocyte chemoattractant protein-1 (MCP-1) is a chemokine that plays a critical role in the recruitment and activation of leukocytes. Here, we describe that multinuclear osteoclast formation was significantly inhibited in cells derived from MCP-1-deficient mice. MCP-1 has been implicated in the regulation of osteoclast cell-cell fusion; however defects of multinuclear osteoclast formation in the cells from mice deficient in DC-STAMP, a seven transmembrane receptor essential for osteoclast cell-cell fusion, was not rescued by recombinant MCP-1. The lack of MCP-1 in osteoclasts resulted in a down-regulation of DC-STAMP, NFATc1, and cathepsin K, all of which were highly expressed in normal osteoclasts, suggesting that osteoclast differentiation was inhibited in MCP-1-deficient cells. MCP-1 alone did not induce osteoclastogenesis, however, the inhibition of osteoclastogenesis in MCP-1-deficient cells was restored by addition of recombinant MCP-1, indicating that osteoclastogenesis was regulated in an autocrine/paracrine manner by MCP-1 under the stimulation of RANKL in osteoclasts.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号