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   1295127篇
  免费   87276篇
  国内免费   3669篇
耳鼻咽喉   16546篇
儿科学   44081篇
妇产科学   35887篇
基础医学   184433篇
口腔科学   35785篇
临床医学   116204篇
内科学   251040篇
皮肤病学   29270篇
神经病学   101760篇
特种医学   52660篇
外国民族医学   391篇
外科学   193976篇
综合类   26356篇
现状与发展   2篇
一般理论   520篇
预防医学   101520篇
眼科学   29181篇
药学   92764篇
  7篇
中国医学   2392篇
肿瘤学   71297篇
  2019年   9883篇
  2018年   16747篇
  2017年   14143篇
  2016年   14913篇
  2015年   17957篇
  2014年   22588篇
  2013年   30999篇
  2012年   46724篇
  2011年   44729篇
  2010年   26034篇
  2009年   26168篇
  2008年   39694篇
  2007年   42557篇
  2006年   42823篇
  2005年   49090篇
  2004年   49214篇
  2003年   43603篇
  2002年   37703篇
  2001年   51444篇
  2000年   50276篇
  1999年   45959篇
  1998年   13514篇
  1997年   11797篇
  1996年   11720篇
  1995年   11217篇
  1994年   10356篇
  1993年   9695篇
  1992年   38134篇
  1991年   37576篇
  1990年   37124篇
  1989年   35715篇
  1988年   32672篇
  1987年   32666篇
  1986年   30523篇
  1985年   29136篇
  1984年   21818篇
  1983年   18317篇
  1982年   10770篇
  1979年   20296篇
  1978年   14430篇
  1977年   12129篇
  1976年   11310篇
  1975年   12464篇
  1974年   15110篇
  1973年   14291篇
  1972年   13345篇
  1971年   12518篇
  1970年   11644篇
  1969年   10853篇
  1968年   10053篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
BACKGROUND Hidradenitis suppurativa (HS) is a difficult disease to treat. Surgery may be curative, but just like cancer surgery, it must be complete to effect a cure. Preoperative imaging of hidradenitis lesions is therefore of interest.
OBJECTIVE The objective was to study the ultrasound characteristics of hidradenitis and compare these to the clinical findings.
MATERIALS AND METHODS Real-time compound imaging ultrasound systems were used (Philips HDI 5000 and iU22) to visualize HS lesions in seven patients and regional controls images from eight healthy volunteers.
RESULTS Hidradenitis-related features were identified: various fluid collections, increased dermal thickness (mean±SD, 3.3±1.0 mm vs. 1.4±0.3 mm for controls) and lower echogenicity of the skin. In comparison with clinical examination, we were able to identify both subclinical lesions and subclinical extension of lesions into clinically normal looking paralesional skin. Hair follicles appeared distended.
CONCLUSION A number of HS features can be identified by ultrasound. These features include both actual lesions and possible predisposing factors such as skin thickness and hair follicle morphology. Ultrasonography can identify the true extent of lesions in HS, which may be of use in the preoperative planning.  相似文献   
992.
993.
994.
Prenatal sonographic features of the rare anomaly of complete duplication of the urinary bladder and urethra are described in this case report. A coronal scan of the fetal pelvis at 29 weeks of gestation revealed two pyriform cystic structures. The umbilical arteries coursed around both of them. They emptied independently of each other. Postnatally the newborn had two vulvae, two anal openings, two bladders and two uteri.  相似文献   
995.
BACKGROUND: Wireless pH studies can offer prolonged pH monitoring, which may potentially facilitate the diagnosis and management of patients with gastroesophageal reflux disease (GERD). The aim of the present study was to evaluate the detection rate of abnormal esophageal acid exposure using prolonged pH monitoring in patients with suspected or refractory GERD symptoms. METHODS: Patients undergoing prolonged ambulatory pH studies for the evaluation of GERD-related symptoms were assessed. Patients with a known diagnosis of GERD were tested on medical therapy, while patients with suspected GERD were tested off therapy. The wireless pH capsules were placed during upper endoscopy 6 cm above the squamocolumnar junction. RESULTS: One hundred ninety-one patients underwent a total of 198 pH studies. Fifty ambulatory pH studies (25%) were excluded from the analysis: 27 patients (14%) had insufficient data capture (less than 18 h on at least one day of monitoring), 15 patients had premature capsule release (7%), seven were repeat studies (3.5%) and one had intolerable pain requiring capsule removal (0.5%). There were 115 patients undergoing pH studies who were off medication, and 33 patients were on therapy. For the two groups of patients, results were as follows: 32 (28%) and 22 (67%) patients with normal studies on both days; 58 (50%) and five (15%) patients with abnormal studies on both days; 18 (16%) and three (9%) patients with abnormal studies on day 1 only; and seven (6%) and three (9%) patients with abnormal studies on day 2 only, respectively. CONCLUSIONS: Prolonged 48 h pH monitoring can detect more abnormal esophageal acid exposure but is associated with a significant rate of incomplete studies.  相似文献   
996.
Hepatic encephalopathy is a reversible state of altered cognition that may occur in patients with acute or chronic liver disease or porto-systemic shunt, and in which known neurological or psychiatric signs may develop. Nitrogenated substances from intestinal digestion reach the brain without being cleared by their passage through the liver due to the presence of porto-systemic shunt. We report two cases of patients with porto-systemic shunt diagnosed with recurrent chronic hepatic encephalopathy refractory to conventional medical treatment. They were satisfactorily treated with shunt embolization using interventionist radiology techniques.  相似文献   
997.
BACKGROUND: An objective of exercise-based cardiac rehabilitation is improvement in patient-reported outcomes such as health-related quality of life as well as anxiety and depressive symptoms. There are no direct comparisons of the effectiveness of inpatient and outpatient exercise-based cardiac rehabilitation programmes on patient-reported outcomes. METHODS: In this non-randomized study we collected patient-reported outcomes data with the MacNew Heart Disease health-related quality of life questionnaire and the Hospital Anxiety and Depression Scale at baseline, 1 month and again 3 months after admission to exercise-based cardiac rehabilitation in a cohort of 216 consecutive patients enrolled either in a 4-week inpatient exercise-based cardiac rehabilitation (n=62) or a 3-month outpatient exercise-based cardiac rehabilitation (n=87) and in a usual care group (n=67) to document the natural course in patient-reported outcome variables without exercise-based cardiac rehabilitation. RESULTS: Although MacNew health-related quality of life scores improved more with inpatient than outpatient exercise-based cardiac rehabilitation by month 1, the improvement was still significant in both groups at month 3 and also in the usual care group when compared to baseline. The health-related quality of life scores in the inpatient group, however, decreased between month 1 and 3 whereas they continued to improve in the outpatient group. The significant reduction in both anxiety and depressive symptoms in both exercise-based cardiac rehabilitation groups by month 1 was maintained at month 3 only with outpatient exercise-based cardiac rehabilitation. No significant changes over the 3 months were observed in the usual care group. CONCLUSION: Significant improvements of 1-month patient-reported outcomes are achieved in patients attending inpatient as well as outpatient exercise-based cardiac rehabilitation when compared with no exercise-based cardiac rehabilitation. In contrast to inpatient exercise-based cardiac rehabilitation, however, outpatient exercise-based cardiac rehabilitation leads to a further improvement of patient-reported outcomes. These results suggest that, if patients have to be admitted for inpatient exercise-based cardiac rehabilitation, this programme should be followed by an outpatient exercise-based cardiac rehabilitation to further improve and stabilize these patient-reported outcome variables.  相似文献   
998.
OBJECTIVE: This study's objective was to assess knowledge of phosphorus compared with other nutrients in patients undergoing maintenance dialysis (MD). DESIGN: We compared knowledge of phosphorus vs. other nutrients important to the MD diet (potassium, sodium, and protein) in patients undergoing hemodialysis (HD) and peritoneal dialysis (PD). We further measured gender, age, education level, and functional health literacy to assess correlations in patient nutrient knowledge. Nutrient knowledge was measured using a 25-item Chronic Kidney Disease Knowledge Assessment Tool for Nutrition (CKDKAT-N), and functional health literacy was measured using the short form of the Test of Functional Health Literacy in Adults (S-TOFHLA). SETTING AND PATIENTS: Patients received maintenance outpatient PD or HD at Wisconsin Dialysis, Inc. (Madison, WI). MAIN OUTCOME MEASURE: The main outcome measure was knowledge of phosphorus vs. knowledge of potassium, sodium, and protein. RESULTS: Forty-seven MD patients participated in the study (29 undergoing HD, 18 undergoing PD, 30 males, 17 females, average age of 58.6 (SD, 13.8) years, and average grade level of 1.4 (SD, 2.6) years of post-secondary education). Thirty-five participants had adequate health literacy, 4 had marginal health literacy, and 8 had inadequate health literacy. The CKDKAT-N scores ranged from 6-21 for 25 items, with a mean score of 13 (SD, 2.91). Knowledge of phosphorus compared with knowledge of other nutrients was poor (0.38 vs. 0.72, P = .003). In a comparison of HD vs. PD patient knowledge, both phosphorus (0.37 vs. 0.42, P = .231) and other nutrients (0.69 vs. 0.80, P = .115) were the same. CONCLUSION: Despite regular dietary instruction, patients undergoing MD have a poor knowledge of dietary phosphorus content, compared with knowledge of other nutrients important in chronic kidney disease. Interestingly, there was no difference in nutrition knowledge when comparing PD and HD patients, despite differences in education level and health literacy between groups.  相似文献   
999.
Ligneous periodontitis (LP) is a rare periodontal disease in which plasminogen deficiency and fibrin deposition both play a part, resulting in characteristic gingival enlargement and periodontal breakdown. Recent data suggest that oxidant/antioxidant changes are significant in the pathology of oral diseases. This study examines the gingival histopathology in 2 cases with LP. To examine the antioxidant (AO) status, the activity of the major AOs glutathione (GSH), catalase (CAT), and glutathione S-transferase (GST) and the malondialdehyde (MDA) levels, a product of lipid peroxidation, were measured and compared with healthy control subjects. The histopathologic examination of the gingiva revealed subepithelial fibrin accumulation and irregular extensive downward proliferation of the epithelium. Biochemical analysis showed that the CAT, GST, and MDA levels were higher in LP patients than in the control subjects, and the GSH level was lower. Our preliminary findings show that in LP, the AO capacity of the gingiva changes or decreases and lipid peroxidation increases, which suggests that oxidative stress is involved in the pathology of the periodontal breakdown observed in this disease.  相似文献   
1000.
We have developed a luminol-based assay using intact islets, which allows for quantification of reactive oxygen species (ROS). In addition, an index capable of characterizing metabolic and mitochondrial integrity prior to transplantation was created based on the capacity of islets to respond to high glucose and rotenone (mitochondrial respiratory chain complex I inhibitor) by production of ROS. To validate this assay, lipid peroxidation and antioxidative defense capacity were evaluated by detection of malondialdehyde (MDA) levels and glutathione peroxidase activity (GPx), respectively. Also, flow cytometric analyses of ROS (dihydroethidine), apoptosis (Annexin V, active caspases), necrosis (Topro3), and mitochondrial membrane potential (JC-1) were done in parallel to correlate with changes in luminol-measured ROS. ATP/ADP ratios were quantified by HPLC and the predictive value of ROS measurement on islet functional potency was correlated with capacity to reverse diabetes in a streptozotocin-induced diabetic NOD.scid mouse model as well as in human transplant recipients. Our data demonstrate that levels of ROS in islets correlate with the percentage of apoptotic cells and their functional potency in vivo. The ROS indices following glucose and rotenone exposure are indicative of metabolic potency and mitochondrial integrity and can be used as surrogate markers to evaluate the quality of islets prior to transplantation.  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