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   605篇
  免费   56篇
  国内免费   4篇
耳鼻咽喉   7篇
儿科学   14篇
妇产科学   7篇
基础医学   79篇
口腔科学   14篇
临床医学   54篇
内科学   170篇
皮肤病学   9篇
神经病学   21篇
特种医学   23篇
外科学   108篇
综合类   23篇
预防医学   33篇
眼科学   13篇
药学   64篇
中国医学   4篇
肿瘤学   22篇
  2023年   25篇
  2022年   14篇
  2021年   25篇
  2020年   19篇
  2019年   22篇
  2018年   35篇
  2017年   16篇
  2016年   24篇
  2015年   24篇
  2014年   35篇
  2013年   49篇
  2012年   57篇
  2011年   51篇
  2010年   33篇
  2009年   21篇
  2008年   26篇
  2007年   27篇
  2006年   20篇
  2005年   21篇
  2004年   12篇
  2003年   13篇
  2002年   11篇
  2001年   8篇
  2000年   8篇
  1999年   15篇
  1998年   6篇
  1997年   6篇
  1996年   5篇
  1993年   2篇
  1992年   3篇
  1991年   6篇
  1989年   1篇
  1988年   3篇
  1987年   1篇
  1986年   2篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1982年   2篇
  1981年   1篇
  1979年   1篇
  1977年   2篇
  1976年   1篇
  1974年   1篇
  1973年   1篇
  1972年   1篇
  1971年   1篇
  1968年   1篇
  1965年   1篇
  1939年   1篇
排序方式: 共有665条查询结果,搜索用时 629 毫秒
71.
AIM: To investigate the associations of hepatitis B virus (HBV) genotype with HBeAg and anti-HBe status, alanine aminotransferase (ALT) levels and HBV-DNA detection in different groups of HBV-infected patients in southwest Iran. METHODS: A total of 89 HBsAg-positive serum samples were collected from the same number of patients. All sera were then investigated to determine HBV DNA and serological markers. For all the polymerase chain reaction (PCR)-positive samples, biochemical, histopathological assays and genotyping were also performed. RESULTS: Genotype D was the only type of HBV foundin different clinical forms of acute and chronic infections. There was a high prevalence of HBeAg-negative HBV- infected patients with chronic hepatitis (52.7%). Out of 55 patients with chronic hepatitis, seven (12.7%) were diagnosed with cirrhosis. A significant association between the presence of anti-HBe antibody and an increase in ALT level, among either HBeAg-negative (P = 0.01) or HBeAg-positive (P = 0.026) patients, was demonstrated. No significant differences were observed between the clinical outcomes of HBeAg-positive and -negative individuals (P = 0.24). CONCLUSION: Genotype D has been recognized as the only type of HBV found in different clinical forms of HBV infections, including cirrhosis, among the residents of southwest Iran. Anti-HBe possibly plays a role in disease progression in some patients with chronic hepatitis, at least for a period of disease.  相似文献   
72.
Bone morphogenetic proteins (BMPs) play important roles in reproduction including primordial germ cell formation, follicular development, spermatogenesis, and FSH secretion. Dragon, a recently identified glycosylphosphatidylinositol-anchored member of the repulsive guidance molecule family, is also a BMP coreceptor. In the present study, we determined the tissue and cellular localization of Dragon in reproductive organs using immunohistochemistry and in situ hybridization. Among reproductive organs, Dragon was expressed in testis, epididymis, ovary, uterus, and pituitary. In the testis of early postnatal mice, Dragon was found in gonocytes and spermatogonia, whereas in immature testes, Dragon was only weakly expressed in spermatogonia. Interestingly, pregnant mare serum gonadotropin treatment of immature mice robustly induced Dragon production in spermatocytes. In adult testis, Dragon was found in spermatocytes and round spermatids. In the ovary, Dragon was detected exclusively within oocytes and primarily those within secondary follicles. In the pituitary, Dragon-expressing cells overlapped FSH-expressing cells. Dragon was also expressed in a number of cell lines originating from reproductive tissues including Ishikawa, Hela, LbetaT2, MCF-7, and JEG3 cells. Immunocytochemistry and gradient sucrose ultracentrifugation studies showed Dragon was localized in lipid rafts within the plasma membrane. In reproductive cell lines, Dragon expression enhanced signaling of exogenous BMP2 or BMP4. The present studies demonstrate that Dragon expression is dynamically regulated throughout the reproductive tract and that Dragon protein modulates BMP signaling in cells from reproductive tissues. The overlap between Dragon expression and the functional BMP signaling system suggests that Dragon may play a role in mammalian reproduction.  相似文献   
73.

Background

Right ventricular (RV) function using myocardial velocities before and after a coronary artery bypass graft (CABG) is not known.

Methods

Using pulsed wave Doppler tissue imaging, RV function was studied in 35 patients before and after CABG. Patients were followed-up for 1 year after the CABG. Myocardial velocities at the tricuspid annulus at the RV free wall were recorded from the apical 4-chamber views.

Results

Both the systolic and early diastolic tricuspid annular velocities (TAV) were significantly reduced 1 month after CABG (P < .001 for both). During the follow-up period, there was no improvement in the diastolic TAV. The systolic TAV showed no improvement 3 months after CABG but recovered partially 1 year after the CABG (systolic velocities were 11.8, 8.7, 8.7 and 9.7 cm/s, the early diastolic velocities were 11.0, 8.1, 8.1 and 8.2 cm/s before and 1 month, 3 months and 1 year after the CABG, respectively). The systolic and early diastolic velocities of the interventricular septum were unchanged during the follow-up period. Unlike the right ventricle, the mitral annular systolic velocity was unchanged shortly after CABG and showed signs of improvement after 1 year (6.4, 6.9, 6.8 and 7.3 cm/s respectively before and after CABG). Patients underwent dobutamine stress echocardiography (DSE) before and 3 months after the CABG. The systolic TAV increased significantly during the DSE before CABG (11.8 vs 15.8 cm/s, P < .001). However, the increase in systolic TAV was limited during DSE 3 months after CABG (8.7 vs 9.9 cm/s, P < .05).

Conclusion

RV function, as assessed by TAV, decreased significantly after CABG and the changes were still evident after 1 year. The response of systolic TAV during DSE was more pronounced before CABG than after CABG.  相似文献   
74.

Background  

To assess clinical utility of computed tomography angiography (CTA) in the diagnosis of chest pain patients presenting to emergency departments (EDs), we conducted a meta-analysis of CTA in patients with suspected acute coronary syndromes (ACSs).  相似文献   
75.
The bone and fat interface is implicated in the pathogenesis of postmenopausal osteoporosis. The association between circulating omentin-1 levels and bone mineral density (BMD) in postmenopausal women has never been assessed. A total of 382 healthy postmenopausal women were randomly selected. Omentin-1, visfatin, adiponectin, the receptor activator of nuclear factor-κB ligand (RANKL), osteoprotegerin, high sensitivity C-reactive protein, degradation products of C-terminal telopeptides of type I collagen, and osteocalcin were measured by highly specific enzyme-linked immunosorbent assay methods. BMD was determined for the lumbar spine (L2-L4) and the proximal femur using dual-energy X-ray absorptiometry. In multivariable-adjusted linear regression, serum omentin-1 levels were inversely correlated with BMD at the lumbar spine (β=-0.11, p=0.020). In multiple regression analyses, serum visfatin and adiponectin levels were not significantly correlated with BMD at different skeletal sites after controlling for age, body mass index, and bone-related markers. However, the highest quartile of adiponectin compared to the lowest quartile, after adjusting for potential confounders, revealed an inverse association with BMD in the lumbar spine (β=-0.19, p=0.010). In conclusion, circulating omentin-1 levels had an inverse correlation with BMD at the lumbar spine in Iranian postmenopausal women. To further understand the role of omentin-1 in bone and mineral metabolism, large-scale longitudinal studies focusing on BMD and osteoporotic fractures are warranted.  相似文献   
76.
77.
The objective of this study was to evaluate the safety of myocardial perfusion scintigraphy with Tc-99 m sestamibi during adenosine stress in patients with recent thrombolytically treated myocardial infarction. Eighty-four patients with thrombolytically treated myocardial infarction, 59 males and 25 females, aged 62·9 ± 8·4, were eligible for myocardial perfusion scintigraphy during adenosine provocation. Exclusion criteria for adenosine stress were hypotension, unstable angina pectoris, cardiac failure, pericarditis and atrioventricular block (AV block) II–III. Adenosine-stress and resting myocardial perfusion scintigraphy was performed 2–5 days after thrombolysis. Scintigraphy at rest was done 24 h after the stress study. Sixty patients (71%) experienced some kind of side-effects during adenosine infusion. The most frequent side-effects were dyspnoea in 43/84 patients (51%) and unspecific chest discomfort in 26/84 patients (31%). During infusion, ST depressions or elevations on ECG were seen in 9 patients (11%), 5 of whom experienced atypical chest discomfort. Five patients (6%) described typical angina but none of them showed electrographic signs of myocardial ischaemia during infusion. Six patients (7%) developed transient AV block I–II. Reversible scintigraphic perfusion defects were seen in 67 patients (79%). No serious complications, such as death, reinfarction or severe arrhythmias, occurred during adenosine infusion or during a 3-day clinical follow-up period. In conclusion, MIBI-SPECT during adenosine stress is a safe diagnostic method that can be performed in most patients early on after thrombolytically treated acute myocardial infarction. Side-effects are common but benign, and not different from those seen in patients with chronic coronary artery disease.  相似文献   
78.
79.
Modification of CAPS-1 for diagnosis of PTSD in Afghan refugees   总被引:1,自引:0,他引:1  
A DSM-III-R based instrument for the assessment of posttraumatic stress disorder (PTSD), the Clinician-Administered PTSD Scale (CAPS-1), was modified to accommodate cultural differences and translated into the Afghan languages Pushto and Farsi (Dari) and administered to 30 Afghan refugees living in the United States. The modified CAPS-1 was found to be practical and reliable. Inter-item correlations were calculated on the frequency and intensity scores for the 17 cardinal symptoms and the eight associated features items of the modified CAPS-1. The four reexperiencing items demonstrated significant independence from the avoidance and arousal symptom clusters. However, the avoidance and arousal symptom clusters were not found to be independent cardinal components of PTSD in our participants. The CAPS-1 criteria for diagnosis of PTSD were met by 50% of the subjects evaluated.  相似文献   
80.
We examined sera from 159 patients with ischemic heart disease and hypertension and from 50 apparently healthy control subjects for content of trace elements, cholesterol, triglyceride, and enzymes. Concentrations of copper, cobalt, cholesterol, and triglyceride were increased in all patients, but calcium was decreased in patients with hypertension, acute myocardial ischemia, and acute myocardial infarction. Also accompanying acute myocardial infarction were decreased concentrations of zinc and iron but increases in nickel, aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase. Magnesium concentration was lower in patients with acute myocardial ischemia. In acute myocardial infarction, the concentrations of copper, zinc, and iron were higher after 21-30 h (as compared with the values at 0-10 h), by which time concentrations of calcium, magnesium, cobalt, and alanine aminotransferase had decreased. The variation in concentration of trace elements in serum from cases of ischemic heart disease and hypertension corresponds to the severity of the disorder.  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