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   475篇
  免费   15篇
  国内免费   68篇
耳鼻咽喉   11篇
儿科学   14篇
妇产科学   21篇
基础医学   47篇
口腔科学   11篇
临床医学   84篇
内科学   82篇
皮肤病学   3篇
神经病学   24篇
特种医学   70篇
外科学   61篇
综合类   18篇
预防医学   11篇
眼科学   3篇
药学   65篇
中国医学   1篇
肿瘤学   32篇
  2023年   5篇
  2022年   10篇
  2021年   9篇
  2020年   9篇
  2019年   10篇
  2018年   7篇
  2017年   6篇
  2016年   9篇
  2015年   10篇
  2014年   15篇
  2013年   22篇
  2012年   22篇
  2011年   20篇
  2010年   16篇
  2009年   18篇
  2008年   28篇
  2007年   75篇
  2006年   24篇
  2005年   29篇
  2004年   13篇
  2003年   12篇
  2002年   16篇
  2001年   10篇
  2000年   12篇
  1999年   10篇
  1998年   18篇
  1997年   17篇
  1996年   18篇
  1995年   15篇
  1994年   4篇
  1993年   6篇
  1992年   3篇
  1991年   6篇
  1990年   5篇
  1989年   13篇
  1988年   9篇
  1987年   6篇
  1986年   3篇
  1985年   1篇
  1984年   3篇
  1983年   1篇
  1980年   3篇
  1978年   2篇
  1977年   5篇
  1976年   1篇
  1975年   1篇
  1973年   1篇
排序方式: 共有558条查询结果,搜索用时 0 毫秒
31.
In this study we reviewed 20 patients with laryngeal squamous cell carcinoma to evaluate the oxidant and antioxidant status on tissue level. Superoxide Dismutase (SOD) and Catalase levels, two important antioxidant enzymes, and Malondialdehyde (MDA) levels, a valuable index of lipid peroxidation, were compared in cancerous and normal tissues of the patients. In cancerous tissue SOD activities were significantly lower than in the normal tissue, while there was no significant difference in MDA levels and Catalase activities. It was also observed that SOD activities significantly decreased as the histopathologic malignancy grades increased in cancerous tissue. These changes in oxidant and antioxidant status in carcinomatous tissue of the larynx are considered to be of great interest.  相似文献   
32.
33.
BACKGROUND: Mesenteric ischemia-reperfusion (I/R) is a well-known event causing both local and remote organ injuries, including the lungs. Recently, several studies indicated that activated leukocyte-endothelial cell interactions play an important role in the mechanisms of these injuries. As a natural inhibitor of serine proteases, antithrombin was shown previously to attenuate the tissue damage after local I/R in several organ systems. Here, we examined the effects of antithrombin on pulmonary injury after mesenteric I/R. METHODS: Wistar albino rats underwent median laparotomy and were randomized into 3 groups: (1) sham-operated control (n = 12), (2) 60 minutes of mesenteric ischemia and 3 hours of reperfusion (n = 12), and (3) antithrombin-pretreated (250 U/kg) group before the I/R (n = 12). At the end of reperfusion, animals were killed and neutrophil sequestration, myeloperoxidase (MPO) activity, and Evans blue dye extravasation in the lung parenchyma were assessed and compared. RESULTS: There was a statistically significant increase in the quantity of Evans blue dye concentration, leukocyte sequestration, and MPO activity in the I/R group when compared with the control group. The pretreatment of animals with antithrombin significantly decreased the pulmonary injury characterized by increased Evans blue dye extravasation, leukocyte sequestration, and MPO activity. CONCLUSION: The data of the present study suggest that mesenteric ischemia and reperfusion induces pulmonary injury characterized by activated neutrophil sequestration and increased microvascular leakage in the lungs. A significant attenuation of intestinal I/R-related lung injury with the use of antithrombin concentrate warrants further studies to elucidate the potential role of this natural serine protease inhibitor in clinical settings.  相似文献   
34.
AIM: The aim of this study was to evaluate the effectiveness of diuretic injection for the measurement of differential renal function (DRF) with technetium-99m dimercaptosuccinic acid (Tc-99m DMSA) scintigraphy in patients with a dilated pelvis. MATERIALS AND METHODS: A total of 46 patients who were referred for both technetium-99m-L,L-ethylenedicysteine (Tc-99m L,L-EC) and Tc-99m DMSA imaging and found to have a dilated collecting system on Tc-99m EC scintigraphy were studied. Four to 5 hours after intravenous injection of Tc-99m DMSA, imaging was performed in the supine position, and posterior, anterior, left and right lateral, and left and right posterior oblique views were taken. After this study, furosemide was administered intravenously and 30 minutes later, additional images in the anterior and posterior views were obtained. RESULTS: The kidneys were evaluated into 2 groups. Group 1 comprised 12 kidneys that had an obstructive curve pattern on Tc-99m EC scans. Group 2 comprised 34 kidneys that had a nonobstructive dilated renogram curve pattern. DRF of the kidneys in each patient were calculated, and the values obtained from the standard and diuretic DMSA scans were compared with each other for all patients and each group. Considering all the patients, the values of mean DRF on both standard and diuretic DMSA images were 55.4%+/-21.2% and 55.4%+/-21.5%, respectively. There were no significant differences between DRF values of each kidney obtained by the 2 methods. When we compared the DRF values in groups 1 and 2, there were again no significant differences. In group 1, the values of mean DRF on standard and diuretic images were 51.7%+/-13.7% and 51.6%+/-13.9%, respectively, and in group 2, the values of mean DRF were 56.7%+/-23.4% and 56.7%+/-23.6%, respectively. CONCLUSION: In view of our study, diuretic administration seems to be an unnecessary intervention because it has no effect on the accuracy of DRF measurements using DMSA scintigraphy in patients with a dilated collecting system whether it is obstructed or not.  相似文献   
35.
Castleman's disease is a rare, benign disease of unknown cause that induces reactive lymph node hyperplasia, most commonly in the mediastinum. It has 2 histologic subtypes: hyaline vascular and plasma cellular. A definitive diagnosis necessitates tissue biopsy. A specimen may be even misdiagnosed as lymphoma in frozen section. Surgery is the treatment of choice for the solitary form, whereas chemotherapy, radiotherapy, and steroids are proposed for the multicentric type. A neck mass diagnosed as Castleman's disease in a 48-year-old woman is reported.  相似文献   
36.
Acute renal failure (ARF) is a cause of high morbidity and mortality associated with long hospital stay, and expensive treatment. The initial approach to patients with ARF should be focused on preventing future injury to the kidney. Two hundred eighty-three ARF patients, treated from January 1996 to June 2002, were retrospectively investigated for their etiology, clinic features, and laboratory characteristics, as well as treatment results and mortality rate. The mean age was 52.3 +/- 18.7 years. Patients with hospital-acquired ARF comprised 38.8% of the sample. Renal causes (60%) were responsible for most ARF patients. They were medical (63.95%), surgical (23.67%), and obstetric (12.4%) causes. Twenty-five percent of patients with ARF had multiple etiologies. Hemolysis elevated liver enzymes low platelets (HELLP) syndrome was seen in the most of the obstetric-related ARF cases. Signs of hypervolemia were present in approximately 50% of the cases. Oliguric patients comprised 59.7% of the sample, and the mean time to oliguria was 5.2 +/- 4.1 days. The necessity of dialysis was greater in oliguric patients (42.6%) and the ratio of complete/partial improvement (82.2%) was greater among non-oligoanuric patients. However, there was no significant difference between mortality rates. Irreversible renal insufficiency did not develop in the non-oliguric cases. Also, 7.4% of ARF patients died, with the main causes being infection (31.8%) and cardiovascular events (27.2%). Medical problems are important in the etiology of ARF as well as obstetric cases. The mortality rate was low in our cases, a situation that may be explained by medical causes being of importance in the etiology. We are of the opinion that early referral of patients to a nephrologist and following treatment in the nephrology clinic may positively affect the outcome.  相似文献   
37.
We investigated the effects of the antioxidant alphae-tocopherol on early- and late-phase fracture healing in a rat model. Sixty male Sprague-Dawley rats were randomized into two groups. The right tibia of each rat was fractured manually under anaesthesia, and fracture sites fixed with intramedullary Kirschner wires. The alpha-tocopherol group received 20 mg/kg alpha-tocopherol intraperitoneally; the control group received intraperitoneal saline injections. Ten rats from each group were sacrificed on day 15, day 45 and day 60. In the alpha-tocopherol group, malondialdehyde concentrations, a measure of lipid peroxidation associated with oxygen free radicals, were significantly decreased on day 15 and day 45 compared with the control group, but had regained the 15-day value on day 60. On histopathological and radiological assessment, fracture healing on day 60 was significantly more advanced in the alpha-tocopherol group. We conclude that alpha-tocopherol has a positive effect on both early and late-phase fracture healing, and may be beneficial in clinical fracture  相似文献   
38.
Glandular hamartoma of the larynx is an extremely rare lesion, and the number of well-documented and acceptable cases is limited. Presenting symptoms may include changes in voice, eating and activity levels, and respiratory complaints. We report on a 14-month-old infant with this rare clinical entity. Direct laryngoscopy revealed a well-mucosalized, encapsulated, firm, 0.5 cm wide and 2.5 cm long lesion that originated from the right aryepiglottic fold and reached into the nasopharynx. The mass was completely excised endoscopically. Histopathological examination revealed a hamartoma, which was composed of glandular elements, mixed with mesodermal tissues. After endoscopic removal of the hamartoma, the child was relieved of the obstruction.  相似文献   
39.
Background: We studied the effects of weight loss on bone metabolism. Methods: 16 consecutive surgically-treated (14 female, 2 male) morbidly obese patients and 65 obese (53 male, 12 female) medically-treated patients were enrolled in an observational study. Surgical treatment for morbidly obese patients was vertical banded gastroplasty (VBG). Studies were performed prior to and 12 months after the start of treatment. Bone mineral density (BMD), bone turnover markers, sex steroids, calcium excretion and parathyroid hormone measurements were done at each visit. Results: Weight loss was more prominent with surgical than with medical treatments. Bone loss was also pronounced in the surgical treatment group, and occurred at the hip level only (P<0.05). Compared to previously reported studies, where the effects of malabsorptive treatments for obesity on bone metabolism were studied, calcium excretion and parathyroid hormone levels did not change after VBG or medical therapy. For both groups, bone markers indicated an increased bone turnover, evidenced by increased urinary excretion of deoxypyridinoline and serum levels of osteocalcin (P<0.05). Sex steroid measurements revealed a decrease in estradiol levels in the surgical treatment group, but not in medical treatment group. This finding was thought to be secondary to less weight loss in the medical group. Conclusion: Our data indicate that weight loss causes bone loss. The bone loss is independent of the method of weight reduction. However, the mechanism of the bone loss is not clear. It may be explained partly by reduced estradiol levels in female patients. Because the mechanisms of bone disease after weight loss remain unclear, it is difficult to determine the most effective treatment. It is important to detect osteopenia early, before fractures occur. Measuring BMD appears to be the only reliable method for screening.  相似文献   
40.
复方葆春袋泡茶质量标准研究   总被引:3,自引:0,他引:3  
目的:制订复方葆春袋泡茶质量标准。方法:双波长薄层扫描法测定了五味子乙素的量,对淫羊藿,五味子,女贞子进行了薄层色谱鉴别。结果;加样回收率平均为97.15%(RSD=1.2%,n=5),标准曲线r=0.9991,重复性RSD=1.4%(n=6)精密度RSD=2.3%(n=6),结论,方法稳定,可靠,可作为该制剂的质量控制方法之一。  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