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   427篇
  免费   9篇
  国内免费   5篇
耳鼻咽喉   15篇
儿科学   20篇
妇产科学   10篇
基础医学   20篇
口腔科学   28篇
临床医学   33篇
内科学   129篇
皮肤病学   4篇
神经病学   16篇
特种医学   10篇
外科学   110篇
综合类   3篇
预防医学   8篇
眼科学   17篇
药学   12篇
中国医学   2篇
肿瘤学   4篇
  2023年   2篇
  2022年   4篇
  2021年   10篇
  2020年   6篇
  2019年   10篇
  2018年   10篇
  2017年   6篇
  2016年   12篇
  2015年   20篇
  2014年   26篇
  2013年   27篇
  2012年   25篇
  2011年   38篇
  2010年   20篇
  2009年   14篇
  2008年   30篇
  2007年   44篇
  2006年   40篇
  2005年   26篇
  2004年   21篇
  2003年   18篇
  2002年   13篇
  2001年   2篇
  2000年   1篇
  1999年   1篇
  1998年   1篇
  1997年   2篇
  1995年   5篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1991年   2篇
  1988年   1篇
  1981年   1篇
排序方式: 共有441条查询结果,搜索用时 0 毫秒
51.
The correlation of coronary artery disease (CAD) with pro-oxidant/antioxidant balance and oxidative DNA damage was investigated.Seventy-seven patients with CAD and 44 healthy individuals as control were included in this study. The comparative ratios of ubiquinol-10/ubiquinone-10, 8-hydroxy-2''-deoxyguanosine/deoxyguanosine and the level of MDA measured by HPLC and the activities of GPX and SOD by colorimetric approach in blood samples obtained from patients with CAD were unraveled.8-OHdG/dG ratios, serum MDA level and GPX activity were found significantly elevated level in serum of CAD patients compared to control group. The SOD activity was observed in stable levels in CAD patients. Ubiquinol-10/ubiquinone-10 ratio was significantly lower in patients with CAD than the controls.The positive correlation was observed between 8-OHdG/dG ratios in both MDA levels and GPX activity, while the significant negative correlation was seemed between the ratio of 8-OHdG/dG and ubiquinol-10/ ubiquinone-10 as well as MDA levels and ubiquinol-10/ ubiquinone-10 ratio.We conclude that, both the disruption of pro-oxidant/antioxidant balance and oxidative stress in DNA may play an important role in the pathogenesis of coronary artery disease.  相似文献   
52.
53.
BACKGROUND AND OBJECTIVE: Acute pancreatitis is an important and fatal disease with high mortality and morbidity. Although the pathogenesis of acute pancreatitis is poorly understood, there are many studies that suggest the role for oxygen free radicals (OFRs) in the development of pancreatitis and its complications and show beneficial effects of scavenger treatment. In the present study, we aimed to investigate whether Egb761, the standardized extract of gingko biloba, restrains the generation of OFRs and ameliorates the histopathologic findings of acute pancreatitis. MATERIALS AND METHODS: Sixty male Sprague Dawley rats were randomly assigned to one of the following experimental groups. In early and late pancreatitis and treatment groups, acute pancreatitis was induced by retrograde infusion of 3% sodium taurocholate. In treatment groups, 100 mg/kg Egb 761 was given intraperitoneally (IP) 24 h and immediately before induction of pancreatitis. Sham-operated rats received isotonic saline instead of sodium taurocholate. After observation times of 3.5 and 12 h, the pancreas was removed for light microscopy and determination of malondialdehyde (MDA) levels as a marker for OFRs-induced lipid peroxidation. Serum samples also were obtained for amylase and lipase levels. RESULTS: There was no significant difference in control and sham-operated groups in terms of histopathologic findings and serum enzyme levels. The tissue concentrations of MDA and serum enzyme levels were significantly elevated in early and late treatment groups as compared with the control group. The treatment with Egb 761 caused significant decrease in serum amylase and lipase levels and histopathologic scores as compared with early and late pancreatitis groups. CONCLUSIONS: Prophylactic application of Egb761 exerts highly beneficial influence on the course of acute pancreatitis, and this seems to be related to the oxygen radical scavenger effect of Egb761.  相似文献   
54.
OBJECTIVE: Research results showed that Chlamydia pneumoniae infection is related to atherosclerosis. C. pneumoniae infection may exacerbate atherogenesis. We investigated the presence of this microorganism for patients who underwent carotid endarterectomy and evaluated clinical values of C. pneumoniae infection on carotid stenosis. METHODS: Twenty patients with carotid stenosis were enrolled in this prospective study between 1997 and 1999. The patients were observed on whether they were positive or negative in four C. pneumoniae measures, namely; IgA titers, IgG titers, presence of electron microscopy, and immunocytochemistry in the endarterectomy specimens. Possible clinical findings for atherosclerosis were also observed of Chlamydial measures such as the percentage of carotid stenosis, cholesterol and triglyceride levels, smoking status, symptomatic or non-transient ischaemic attack or stroke, previous ischaemic event, calcification at surgery, ulceration on angiographies, ulceration at surgery and hypertension were included in this evaluation. RESULTS: Specific C. pneumoniae IgG were detected as positive in 9 (45%) of 20 patient samples. These patients were regarded as having chronic Chlamydia pneumoniae infection. None of the patients were positive for IgA antibody. This result demonstrated no evidence of reinfection. Immunocytochemistry and electron microscopy were positive in 7 (35%) of the 20 patients and correlated with positive serological results. The proportion of previous ischaemic events, calcification at surgery, ulceration on angiography, and ulceration at surgery were found significantly higher ( p < 0.05 ) for patients who are positive for chlamydial measures than those who are negative. CONCLUSION: The results of this study demonstrated an association between C. pneumoniae to atherosclerosis. The proportion of patients who are positive for Chlamydia measures (IgG titers, electron microscopy, and immunocytochemistry) is significantly higher for those who were positive for each of these clinical variables (PIE, CALCI, U1, and U2) than who were negative. We emphasise, the higher incidence in clinical variables of PIE, CALCI, U1, and U2 in Chlamydia measures positive group may support the association of C. pneumoniae with atherosclerotic events.  相似文献   
55.
56.
Acquired pseudoaneurysm of the left ventricle is a rare disorder that usually ofvccurs after transmural myocardial infarction or after cardiac surgery. Pseudoaneurysms are usually detected because of symptoms; less often incidentally. Here we present a case of pseudoaneurysm as a result of unknown etiology causing myocardial bridging like image at angiography.  相似文献   
57.
It is unclear why some species become successful invaders whilst others fail, and whether invasive success depends on pre-adaptations already present in the native range or on characters evolving de-novo after introduction. Ants are among the worst invasive pests, with Lasius neglectus and its rapid spread through Europe and Asia as the most recent example of a pest ant that may become a global problem. Here, we present the first integrated study on behavior, morphology, population genetics, chemical recognition and parasite load of L. neglectus and its non-invasive sister species L. turcicus. We find that L. neglectus expresses the same supercolonial syndrome as other invasive ants, a social system that is characterized by mating without dispersal and large networks of cooperating nests rather than smaller mutually hostile colonies. We conclude that the invasive success of L. neglectus relies on a combination of parasite-release following introduction and pre-adaptations in mating system, body-size, queen number and recognition efficiency that evolved long before introduction. Our results challenge the notion that supercolonial organization is an inevitable consequence of low genetic variation for chemical recognition cues in small invasive founder populations. We infer that low variation and limited volatility in cuticular hydrocarbon profiles already existed in the native range in combination with low dispersal and a highly viscous population structure. Human transport to relatively disturbed urban areas thus became the decisive factor to induce parasite release, a well established general promoter of invasiveness in non-social animals and plants, but understudied in invasive social insects.  相似文献   
58.
59.
60.
BACKGROUND: Serum gamma-glutamyl transferase (GGT) activity, an enzyme responsible for the extracellular catabolism of antioxidant glutathione, may directly take part in atherogenesis and evolve as a potential biochemical risk indicator of cardiovascular morbidity and mortality. An important characteristic of coronary artery ectasia (CAE) is the fact that in 85% of the cases, atherosclerotic coronary disease accompanies it. The relation between CAE and serum GGT activity has not been studied so far. Hence, we decided to investigate the serum GGT level in patients with CAE. METHODS: We measured serum GGT activity in 88 consecutive patients (48 males) with isolated CAE and 86 patients with coronary artery disease (CAD) and 84 controls. CAE was defined as being without any stenotic lesions with a visual assessment of the coronary arteries showing a luminal dilatation 1.5-fold or more of the adjacent normal coronary segments. Four subgroups were created in accordance with the CAE extension in coronary arteries. RESULTS: There were no statistically significant differences in serum GGT activity among CAE and CAD groups. Serum GGT activity was found significantly increased in patients in both CAE and CAD groups, compared with those in control group (P<0.001, P<0.001, respectively). According to the CAE severity, there were no statistically significant differences in CAE among these subgroups. CONCLUSION: We have shown for the first time that patients with CAE have higher serum GGT activity compared with controls with normal coronary angiograms. Hence, serum GGT activity can be used as a follow-up marker in patients with CAE.  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