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   928篇
  免费   73篇
  国内免费   2篇
耳鼻咽喉   36篇
儿科学   49篇
妇产科学   15篇
基础医学   90篇
口腔科学   16篇
临床医学   60篇
内科学   257篇
皮肤病学   14篇
神经病学   58篇
特种医学   29篇
外科学   307篇
综合类   10篇
预防医学   7篇
眼科学   15篇
药学   20篇
肿瘤学   20篇
  2024年   1篇
  2023年   8篇
  2022年   14篇
  2021年   25篇
  2020年   16篇
  2019年   27篇
  2018年   27篇
  2017年   28篇
  2016年   35篇
  2015年   49篇
  2014年   49篇
  2013年   74篇
  2012年   69篇
  2011年   66篇
  2010年   44篇
  2009年   51篇
  2008年   61篇
  2007年   63篇
  2006年   63篇
  2005年   59篇
  2004年   57篇
  2003年   35篇
  2002年   60篇
  2001年   11篇
  2000年   2篇
  1999年   2篇
  1998年   2篇
  1997年   3篇
  1996年   1篇
  1971年   1篇
排序方式: 共有1003条查询结果,搜索用时 15 毫秒
101.

Purpose

To evaluate the efficacy of two level pedicle substraction osteotomies (PSOs) planned preoperatively with a computer software, in the patients with severe fixed sagittal plane deformities.

Methods

In the literature, there are studies indicating that two level PSOs may be required in severe cases. However, the results of two level PSOs preoperatively planned with computer software-assistance have not yet been reported in the English literature. Severe fixed sagittal plane deformities of 11 patients are described. Preoperative surgical planning was done with the aid of a computer software. Two level PSOs were indicated after the process. After the application of the indicated surgical technique, clinical and radiological results were evaluated in the preoperative, the early postoperative periods and during the last follow-up.

Results

The mean sagittal vertical axis was found as 190.5 (range 161–220) mm in the preoperative period, 23.5 (range ?27 to 61) mm in the early postoperative period (P < 0.001) (87.7 % correction) and 34.5 (range ?3 to 55) mm during the last follow-up (P < 0.001). The mean pelvic tilt (PT) significantly decreased from 38.3° (range 21°–63°) preoperatively to 23.8° (range 18°–42°) postoperatively (P = 0.008) and to 27.5° (range 17°–42°) during the last follow-up (P = 0.042). The mean lumbar lordosis (LL) was 2.8° (range ?29° to 20°) preoperatively, ?35.6° (range ?54° to 23°) early postoperatively (P < 0.001) and ?33.6° (range ?52° to 20°) during the last follow-up (P < 0.001). The average amount of bleeding was 5345 (range 2600–7415) ml.

Conclusion

Although a statistically significant correction was obtained, the mean PT and PI–LL value could not be restored in physiological limits during the last follow-up. Thus, two level PSOs performed after computer software (surgimap) assisted preoperative planning failed to correct severe fixed sagittal plane deformities. Besides, this procedure is of possible risks for major complications such as a result of excessive bleeding. We recommend that two level PSOs should be rarely indicated, but preferred as an alternative technique only in the most severe cases.
  相似文献   
102.
103.
104.
105.
Replacement of iron with cobalt(III) selectively introduces a deep trap in the folding-energy landscape of the heme protein cytochrome c. Remarkably, neither the protein structure nor the folding thermodynamics is perturbed by this metal-ion substitution, as shown by data from spectroscopic and x-ray diffraction experiments. Through kinetics measurements, we have found parallel folding pathways involving several different misligated Co(III) species, and, as these folding intermediates persist for several hours under certain conditions, we have been able to elucidate fully their spectroscopic properties. The results, along with an analysis of the fluorescence energy-transfer kinetics during refolding, show that rapidly equilibrating populations of compact and extended polypeptide conformations are present until all molecules have reached the native structure. These measurements provide direct evidence that collapsed denatured structures are not substantially more stable than extended conformations of cytochrome c.  相似文献   
106.
Calciphylaxis may be considered a small vessel vasculopathy which is generaly associated with end-stage renal disease and hyperparathyroidism. The precise pathogenesis of the disease is not known. It needs sensitizers and challengers to occur. Steroids and immunosuppressive drugs including methotrexate are among those challenger agents. Calciphylaxis in collagen vascular diseases is rare. Only one case in rheumatoid arthritis was recently reported. Here we describe a case of calciphylaxis associated with active rheumatoid arthritis. This patient had active disease despite treatment of steroids and methotrexate for a long time. She died shortly after the diagnosis of calciphylaxis due to sepsis.  相似文献   
107.
First Turkish experience with the MicroMed DeBakey VAD   总被引:1,自引:0,他引:1  
Mechanical bridging to cardiac transplantation with a ventricular assist device may be a life-saving procedure for patients with end-stage heart failure. Here we report our 3 cases of patients implanted with the MicroMed DeBakey VAD (ventricular assist device). Three male patients, aged 37, 41, and 40, had end-stage left heart failure due to idiopathic cardiomyopathy and were listed for cardiac transplantation. They had progressive hemodynamic deterioration. Although Patient 1 underwent surgery, after device implantation, for bowel necrosis caused by thromboemboli of unknown origin, heart transplantation was performed 70 days after implantation. Pump thrombosis occurred in Patient 2 on the 120th day. Outflow graft ligation was performed because the patient refused a pump exchange. This patient died on the 25th day after ligation and the 145th day after ventricular assist device implantation. A heparin-coated version of the device was implanted in Patient 3, whose preoperative profound biventricular failure had been improved by inotropic medication and intra-aortic balloon pump support. Successful heart transplantation was performed 161 days after implantation. These are the 1st implantations of a left ventricular assist device in Turkey. From these cases, we have learned that the DeBakey VAD supplies adequate blood flow during the bridging period and, due to its simplicity, portability, and low infection rate, enables discharge of the patient from the hospital. However, preoperative psychological evaluation and postoperative psychological support are important for a successful bridging procedure, as is close observation of coagulation and of pump operation.  相似文献   
108.
OBJECTIVE: We investigated the level of homocysteine (HCY) and its relation with vitamin B12, folate and oxidative stress in patients with beta-thalassaemia major. MATERIAL AND METHODS: Plasma HCY, methionine, advanced oxidation protein products (AOPP) and serum vitamin B12, folate, ferritin and total antioxidant capacity (TAC) were determined in 32 thalassaemic patients and 27 control subjects. RESULTS: HCY (6.44+/-0.44 versus 8.71+/-0.57 micromol/L), methionine (12.57+/-1.8 versus 22.2+/-3.8 micromol/L), folate (9.14+/-0.48 versus 15.38+/-0.71 nmol/L) and TAC (0.34+/-0.03 versus 0.56+/-0.03 mmol/L) significantly decreased in thalassaemic patients, whereas AOPP (20.26+/-1.8 versus 11.30+/-0.2 micromol/L) and ferritin (3481.0+/-512 versus 46.9+/-4.6 ng/mL) significantly increased. Vitamin B12 levels were similar in both groups (259.1+/-16.6 versus 228.9+/-7.4 pmol/L). CONCLUSIONS: These findings suggest that increased and uncompensated oxidative stress may lead to an increment in HCY catabolism in thalassaemic patients.  相似文献   
109.
The aim of this study was to investigate the relationship between established risk factors and segmental localization of coronary artery disease. A total of 2760 patients who underwent coronary angiography were enrolled into the study. Coronary angiographic segmental evaluation was performed according to the scheme of American Heart Association. Patients were classified into 2 groups (group 1: normal coronary artery segments, group 2: coronary artery segments with coronary artery disease). Smoking was highly related with left main coronary artery disease (odds ratio = 7.5; P = .005). Diabetes mellitus and male sex increased the risk of atherosclerosis in all coronary vasculature (odds ratio = 2.7-2.2; P < .001-P < .001). Hypertension was correlated with distal coronary artery (odds ratio = 1.4; P < .001) and family history with distal circumflex lesions (odds ratio = 4.5; P = .005) High triglyceride levels were associated with right coronary artery lesions (odds ratio = 1.00; P =.03). The effect of advanced age was small (odds ratio = 1.08; P < .001). Risk factors may be predictive for segmental localization.  相似文献   
110.
We have studied 918 chromosomes for mutations leading to beta-thalassemia and sickle cell anemia, which are the two most frequently found monogenic disorders in Antalya, Turkey. Three hundred and seventy-seven postnatal and 82 prenatal cases were studied between 2000 and May 2003 in our center using reverse dot blot hybridization (RDBH) with 22 probes specific for Mediterranean populations. In this study, IVSI-110 (G-->A) appeared to be the most common mutation with an occurrence rate of 44.4% among the 16 different mutations found to be associated with beta-thalassemia. Heterozygosity for IVSI-110 was the most prevalent combination, whereas 34 of our 377 postnatal cases showed homozygosity for this mutation, a genotype leading to beta-thalassemia major. The total percentage of postnatal patients clinically diagnosed as beta-thalassemia major was 18.6%, whereas 5% of the cases were diagnosed clinically as beta-thalassemia intermedia. One new Hb variant, Hb Antalya, and one new mutation, Cod 3 (+T) were found. HbS accounted for 10.3% of all mutations; homozygosity was found in 1.9% of all cases. Of the 82 cases analysed prenatally for beta-globin gene mutations and by cytogenetic techniques for possible chromosomal abnormalities, 21 fetuses were found to be affected with beta-globin gene mutations. One of these fetuses was also found to have a 45,X karyotype, and 1 had a 46,XY/47,XY,+22 karyotype. Quite a high rate of consanguineous marriages in Antalya (35.17%) renders mutation screening, genetic counseling, and educational programs held by our Thalassemia Unit essential. This study was the first to be performed specifically in our region where hemoglobinopathies are most frequent as a consequence of migrations of racially and culturally distinct groups to the area in the distant past.  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