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   251篇
  免费   20篇
耳鼻咽喉   1篇
儿科学   4篇
妇产科学   6篇
基础医学   29篇
临床医学   20篇
内科学   62篇
神经病学   24篇
特种医学   8篇
外科学   42篇
综合类   2篇
预防医学   47篇
药学   11篇
中国医学   2篇
肿瘤学   13篇
  2022年   7篇
  2021年   11篇
  2020年   3篇
  2019年   6篇
  2018年   5篇
  2017年   3篇
  2016年   9篇
  2015年   6篇
  2014年   4篇
  2013年   9篇
  2012年   14篇
  2011年   12篇
  2010年   8篇
  2009年   10篇
  2008年   19篇
  2007年   13篇
  2006年   17篇
  2005年   6篇
  2004年   15篇
  2003年   9篇
  2002年   4篇
  2001年   1篇
  2000年   5篇
  1997年   2篇
  1993年   2篇
  1992年   3篇
  1991年   7篇
  1990年   7篇
  1989年   7篇
  1988年   4篇
  1987年   6篇
  1986年   5篇
  1985年   4篇
  1984年   5篇
  1983年   1篇
  1982年   1篇
  1981年   2篇
  1980年   1篇
  1979年   7篇
  1977年   1篇
  1975年   1篇
  1974年   2篇
  1973年   1篇
  1972年   1篇
  1968年   2篇
  1966年   2篇
  1965年   1篇
排序方式: 共有271条查询结果,搜索用时 15 毫秒
1.
The purpose of this study was to use a meta-analytical technique to examine the efficacy of surgical repair of pectus excavatum on pulmonary function. Studies were retrieved via computerized literature searches, cross-referencing from original and review articles. Inclusion criteria were as follows: (1) reporting quantitative measures of preoperative and postoperative pulmonary function; (2) published in the English language; (3) indexed between January 1960 and September 2005; (4) reporting the duration between which preoperative and postoperative assessments were conducted; and (5) describing the pulmonary assessment procedures. The titles and abstracts of potentially relevant articles were reviewed to determine whether they met the criteria for inclusion. Twelve studies representing 313 pectus excavatum patients met the inclusion criteria and were used for the meta-analysis. Random-effects modeling yielded a mean weighted effect size (ES) for pulmonary function which was statistically nonsignificant (ES=0.08, 95% CI=-0.20 to 0.35; P=0.58). The findings of the present study indicated that surgical repair of pectus excavatum does not significantly improve pulmonary function. These findings, however, may be a result of testing pulmonary function under conditions in which pectus excavatum does not manifest itself.  相似文献   
2.
B Iványi  G Mohácsi  S Sonkodi  J Ormos 《Orvosi hetilap》1992,133(38):2431-2434
IgG lambda type of monoclonal gammopathy and thin basement membrane nephropathy were established in a middle-aged man examined because of persistent haematuria, lambda light-chain proteinuria and moderately diminished renal function. A 10% level of plasmocytosis was verified by bone-marrow aspiration. The more than 6-year follow-up showed the gammopathy to be benign. The thin basement membrane nephropathy was verified by electronmicroscopic analysis of renal tissue obtained by percutaneous renal biopsy: lamina densa of the glomerular capillaries thinned to 30-100 nm. In spite of the usually good outcome of thin basement membrane nephropathy, in this case it was accompanied by glomerular sclerosis, subsequent destruction of nephrons, hypertensive vascular alterations and a clinical deterioration of the renal function after 4 years. A rebiopsy excluded the possible complications (amyloidosis, non-amyloid immunoglobulin nephropathy, cylinder nephropathy, etc) of light-chain proteinuria.  相似文献   
3.
The authors examined the possible role of HPL in the onset of labour. The HPL level of the maternal vein, the umbilical cord vein and artery was compared in vaginal mature (n = 16) and premature (n = 52) deliveries. The HPL concentration was also examined in mature (n = 18) and premature (n = 18) deliveries performed by caesarean section prior to the onset of labour. The results showed that: the serum HPL level in the maternal vein, the umbilical cord vein and artery was lower during the 33rd-36th and the 40th weeks in cases of vaginal delivery compared to elective caesarean section; The artery/vein ratio decreases during labour (A/V X 100 value), indicating that HPL metabolism in the fetus decreases during regular labour pains; The onset of premature labour and delivery was associated with lower HPL levels compared to normal pregnancy. The authors assume that the lower HPL level found in cases of vaginal delivery may be due to reduced placental perfusion, but they do not exclude the possible association of lower HPL concentrations in cases of premature delivery.  相似文献   
4.
Conflicting results are to be found in the literature on the relationship between the M235T polymorphism of the angiotensinogen (AGT) gene and hypertension. The controversy may be due to insufficient numbers of subjects, the variability of the inclusion criteria and the different genotype analysis methods used. We have experienced that the most frequently used, original polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method involves significant uncertainties when the TT genotype is determined, independently of the restriction digestion. To make the determination more accurate, we improved the PCR by designing a new antisense primer containing only one mismatch instead of the two in the original protocol and also by adding DMSO to the PCR reaction mixture. The original and our improved methods were compared by using DNA from 123 patients: parallel determinations resulted in values of 33 MM, 90 MT and 0 TT with the original method and of 33 MM, 56 MT and 34 TT with the improved RFLP protocol. In summary, a plausible explanation for some of the conflicting data published on AGT M235T polymorphism may be that inaccuracies arose during the determination of the genotype.  相似文献   
5.
Summary Ultrastructural features of muscle spindles were studied in biopsy material from 100 patients suffering from classical rheumatoid arthritis. Thickening of the outer capsule, increased amount of extracellular ground substance within the inner capsule, and marked thickening of the basement membrane of capillary blood vessels supplying the muscle spindles were observed. Chronic inflammatory cells and macrophages were present within the spindles. Changes affecting the intrafusal muscle fibres were also seen. They were manifest as atrophy and degeneration of the intrafusal muscle fibres, absence of the specialised junctional complexes, and of the intercellular bridges, microladders and satellite cells. It is suggested that the changes affecting the intrafusal muscle fibres are probably secondary. Damage to the myelinated nerves was present, while the sensory and motor nerve endings were well preserved.Temporary Research Fellow the Rotterdam Centre for Rheumatic Disease Present address: Division of Pathology, Department of Obstetrics and Gynaecology, University of Chicago, Chicago, Illinois 60637, USA  相似文献   
6.
Endothelial nitric oxide synthase (eNOS) is regulated by phosphorylation of Ser(1177) and Thr(495), which affects NO bioavailability. Cigarette smoke disturbs the eNOS-cGMP-NO pathway and causes decreased NO production. Here the authors investigated the acute effects of cigarette smoke on eNOS phosphorylation, focusing on protein kinases (PKs). Endothelial cell culture was concentration- and time-dependently treated first with cigarette smoke buffer (CSB), then with reduced glutathione (GSH) or various PK inhibitors (H-89, LY-294002, Ro-318425, and ruboxistaurin). eNOS, phospho-Ser(1177)-eNOS, phospho-Thr(495)-eNOS, Akt(PKB), and phospho-Akt protein levels were determined by Western blot. CSB increased the phosphorylation of eNOS at Ser(1177) and more at Thr(495) in a concentration- and time-dependent manner (p < .01, p < .05 versus control, respectively) and resulted in the dissociation of the active dimeric form of eNOS (p < .05). GSH decreased the phosphorylation of eNOS at both sites (p < .05 versus CSB without GSH) and prevented the decrease of dimer eNOS level. CSB treatment also decreased the level of phospho-Ser(473)-Akt (p < .05 versus control). Inhibition of PKA by H-89 did not affect CSB-induced phosphorylation, whereas the PKB inhibitor LY-294002 enhanced it at Ser(1117). The PKC blockers Ro-318425 and ruboxistaurin augmented the CSB-induced phosphorylation at Ser(1177) but decreased phosphorylation at Thr(495) (p < .05 versus CSB). Cigarette smoke causes a disruption of the enzymatically active eNOS dimers and shifts the eNOS phosphorylation to an inhibitory state. Both effects might lead to reduced NO bioavailability. The shift of the eNOS phosphorylation pattern to an inhibitory state seems to be independent of the PKA and phosphoinositol 3-kinase (PI3-K)/Akt pathways, whereas PKC appears to play a key role.  相似文献   
7.
The authors analyse the histopathological features and clinical behaviour of 325 superficial (Ta, T1) tumours of 232 patients with bladder cancer. Each of the tumours was treated by TUR using differentiating resection technique and multiple cold biopsy was performed in 197 patients. The recurrence and progression of superficial tumours are examined during the 3-192 months follow up time. It is stressed the role of incomplete TUR in the "recurrence" (tumour persistence). The opinion of the authors is, that superficial bladder tumours can not be considered a homogen group, there are significant differences between Ta and T1 stage in recurrence, neoplastic progression and histopathological features as well.  相似文献   
8.
9.
Thrombospondin-1 (TSP-1) is a known inhibitor of angiogenesis; however, a skeletal muscle phenotype of TSP-1 null mice has not been investigated. The purposes of this study were to compare and contrast TSP-1 null and wild-type mice by examining the following: (1) capillarity in the skeletal and cardiac muscles; (2) fibre type composition and oxidative enzyme activity in the hindlimb; and (3) the consequences of TSP-1 gene deletion for exercise capacity. In TSP-1 null mice, maximal running speed was 11% greater and time to exhaustion during submaximal endurance running was 67% greater compared with wild-type mice. Morphometric analyses revealed that TSP-1 null mice had higher ( P < 0.05) capillarity in the heart and skeletal muscle than wild-type mice, whereas no differences for fibre type composition or oxidative enzyme activity were present between the two groups. Cardiac function, as measured by transthoracic echocardiography, revealed no difference in myocardial contractility but greater left ventricular end-diastolic and systolic dimensions, corresponding to an elevated heart mass in the TSP-1 null mice. The results of this study indicate that TSP-1 is an important endogenous negative regulator of angiogenesis that prevents excessive capillarization in the heart and skeletal muscles. The increased capillarity alone was sufficient to increase ( P < 0.05) exercise capacity. These data demonstrate that the capillary-to-muscle interface is a critical factor that limits oxygen transport during exercise.  相似文献   
10.
Hyperglycemia increases oxidative stress in various tissues and leads to diabetic cardiovascular complication. Dyslipidemia, such as an increase in oxidized low-density lipoprotein (LDL), is well recognized in diabetic patients with hyperglycemia. However, the mechanism by which hyperglycemia causes the increased LDL oxidation remains unclear. Albumin is the most abundant protein in the circulation, and can function as an antioxidant. Therefore, we examined whether glycoxidative modification inhibits the antioxidant activity of albumin to LDL oxidation and clarified the mechanism by which this modification may suppress its antioxidant activity. Human serum albumin (HSA) was incubated in phosphate-buffered saline with and without glucose at 37°C for up to 8 weeks under aerobic conditions (referred to as glycoxidation (goHSA) and oxidation (oHSA), respectively). Metal chelator-treated, nonoxidative HSA (chHSA) and freshly prepared HSA (fHSA) were used as controls. N ε-(carboxymethyl)lysine (CML), a glycoxidative product, was determined by enzyme-linked immunosorbent assay. Oxidation was estimated by measuring the thiols of the HSA molecule. Copper-mediated oxidation of LDL was conducted in the presence or absence of modified HSAs at 37°C for 6 days. Malondialdehyde and negative charge of LDL were measured. To clarify the mechanism of reduced antioxidant activity of HSA, we examined firstly the binding activity of modified HSAs to copper, and secondly the effects of free radical scavengers on the formation of malondialdehyde. CML was formed in goHSA in a time- and concentration-dependent manner. Both goHSA and oHSA significantly decreased the contents of free thiol groups compared to ch- and fHSAs. The antioxidant activity of goHSA to LDL oxidation was the lowest among various modified HSAs. The oHSA showed a moderate decrease in antioxidant activity. The binding activity of go- and oHSAs to copper was lower than that of ch- and fHSAs. The formation of MDA from LDL oxidation in the presence of goHSA was completely inhibited by Tiron (1,2-dihydroxy-3,5-benzenedisulfonic acid) and superoxide dismutase. In contrast, catalase and mannitol had no effect. Our results indicate that in vitro glycoxidation of HSA induced a marked loss of antioxidant activity of this molecule to copper-mediated oxidation of LDL, which may be caused by the generation of superoxide. Received: December 17, 2001 / Accepted: June 28, 2002 Acknowledgments The authors thank Drs. Ryoji Nagai and Seikoh Horiuchi (Department of Biochemistry, Kumamoto University School of Medicine, Kumamoto, Japan) and Drs. Hiroyuki Itabe and Tatsuya Takano (Department of Microbiology and Molecular Pathology, Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Kanagawa, Japan) for kindly supplying antibodies. We also thank Associate Professor Takeo Yamaguchi (Department of Chemistry, Faculty of Science, Fukuoka University) for the ESR experiment and Miss Satoko Nagano for her excellent technical assistance. This work was supported by a Grant-in-Aid from the Ministry of Education, Science, Sports and Culture of Japan (No. 14570171) and in part by funds from the Central Research Institute of Fukuoka University (No. 016004). Correspondence to N. Sakata  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