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   2739篇
  免费   123篇
  国内免费   23篇
耳鼻咽喉   80篇
儿科学   180篇
妇产科学   169篇
基础医学   180篇
口腔科学   168篇
临床医学   179篇
内科学   468篇
皮肤病学   58篇
神经病学   254篇
特种医学   103篇
外科学   740篇
综合类   22篇
一般理论   1篇
预防医学   45篇
眼科学   65篇
药学   82篇
肿瘤学   91篇
  2024年   3篇
  2023年   32篇
  2022年   63篇
  2021年   110篇
  2020年   78篇
  2019年   86篇
  2018年   104篇
  2017年   95篇
  2016年   125篇
  2015年   145篇
  2014年   141篇
  2013年   166篇
  2012年   224篇
  2011年   226篇
  2010年   123篇
  2009年   106篇
  2008年   176篇
  2007年   186篇
  2006年   161篇
  2005年   127篇
  2004年   102篇
  2003年   68篇
  2002年   81篇
  2001年   27篇
  2000年   30篇
  1999年   21篇
  1998年   8篇
  1997年   10篇
  1996年   7篇
  1995年   14篇
  1994年   3篇
  1993年   5篇
  1992年   8篇
  1991年   5篇
  1990年   5篇
  1989年   2篇
  1988年   2篇
  1987年   3篇
  1986年   3篇
  1985年   1篇
  1984年   2篇
  1968年   1篇
排序方式: 共有2885条查询结果,搜索用时 0 毫秒
81.
Disruption of the integrity of nasal alar subunit as a result of previous ablative surgery or trauma may cause severe retraction or notching. This article presents a technique of successful reconstruction of the severely retracted alar margin due to prior ablative surgery or trauma by utilizing a turn-in flap brought from the nasal skin adjacent to the alar defect for inner lining, an auricular cartilage graft for alar margin support and a two-stage nasolabial flap for skin coverage.  相似文献   
82.
International Urology and Nephrology - We aimed to investigate the relationship between Vitamin D level and quality of life in patients undergoing peritoneal dialysis as renal replacement therapy....  相似文献   
83.
The purpose of this study is to investigate the effects of L-arginine on spermatological parameters, seminal plasma nitric oxide levels and arginase enzyme activities. Fertile rams that are 2–3 years old and weighing 50–60 kg were used as material. The semen was collected by artificial vagina at 1st, 4th, 24th, 48th, 72nd, 96th and 120th hours for the control group before L-arginine administration. For treatment groups, L-arginine was administered intraperitoneally at a dose of 5 mg kg−1 bw−1 and semen was collected at the time point described for the control group. Spermatological characteristics of semen samples (semen volume, pH, sperm motility, concentration and abnormal sperm rate), seminal plasma nitric oxide levels and arginase enzyme activities were determined. Increased seminal plasma nitric oxide level (p < .01), seminal plasma arginase activity (p < .01), semen volume (p < .05), semen mass activity (p < .05), sperm motility (p < .05) and concentration (p < .01) and decreased abnormal sperm rate (p < .05 and p < .01) were observed by L-arginine administration. In conclusion, it may be concluded that L-arginine application in rams during the breeding season may have positive effects on rams' reproductive performance.  相似文献   
84.
A review of the literature indicated that sirtuin-1 expression, a regulator of nitric oxide bioavailability in erectile dysfunction (ED) after melatonin therapy, has not yet been investigated. The objective of this study was to evaluate the protective effects of melatonin for erectile function with sirtuin-1 protein expression in type 1 diabetic rat models. Fifty male Sprague Dawley rats were placed into five groups. Except for those in the control group (C), each animal received a single dose (60 mg/kg) of streptozotocin to induce diabetes. The animals were placed into the diabetes (D) group, insulin (I) group (6 U/kg/day), melatonin (Mel) group (10 mg kg−1 day−1) and combined treatment (I + Mel) group. Ten weeks later, the serum testosterone levels, intracavernosal pressure (ICP), mean arterial pressure (MAP), malondialdehyde (MDA), cyclic guanosine monophosphate (c-GMP), 8-hydroxydeoxyguanosine (8-OHdG), nitric oxide synthase (NOS), caspase-3 activity, sirtuin-1 and endothelial nitric oxide synthase (eNOS) protein expression and histological findings were assessed. The mean ICP/MAP ratio for the D group was lower than the mean ratios for the other groups. The treatment groups, particularly the I + Mel group, exhibited lower 8-OHdG and MDA levels and caspase-3 activity than the D group. The sirtuin-1 and eNOS expression and cavernosal tissue (CT) histology seemed to have been preserved by the melatonin and/or insulin therapy. These results were indicative of a profound protective effect of melatonin by the activation of sirtuin-1 protein expression against hyperglycemia-induced oxidative CT injury.  相似文献   
85.
46,XX testicular disorder of sex development (46,XX TDSD) is a relatively rare condition characterised by the presence of testicular tissue with 46,XX karyotype. The present study aims to reveal the phenotype to genotype correlation in a series of sex-determining region Y (SRY)-positive 46,XX TDSD cases. We present the clinical findings, hormone profiles and genetic test results of six patients with SRY-positive 46,XX TDSD and give the details and follow-up findings of our three of previously published patients. All patients presented common characteristics such as azoospermia, hypergonadotropic hypogonadism and an SRY gene translocated on the terminal part of the short arm of one of the X chromosomes. Mean ± standard deviation (SD) height of the patients was 164.78 ± 8.0 cm. Five patients had decreased secondary sexual characteristics, and three patients had gynaecomastia with varying degrees. Five of the seven patients revealed a translocation between protein kinase X (PRKX) and inverted protein kinase Y (PRKY) genes, and the remaining two patients showed a translocation between the pseudoautosomal region 1 (PAR1) of X chromosome and the differential region of Y chromosome. X chromosome inactivation (XCI) analysis results demonstrated random and skewed XCI in 5 cases and 1 case, respectively. In brief, we delineate the phenotypic spectrum of patients with SRY-positive 46,XX TDSD and the underlying mechanisms of Xp;Yp translocations.  相似文献   
86.
87.
88.
89.
Therapeutic delays in cases of external incarcerated hernias typically result in increasing morbidity, mortality, and health expenditures. We investigated the diagnostic role of blood fibrinogen level, white blood count (WBC), mean platelet volume (MPV), and platelet distribution width (PDW) in patients with incarcerated hernia. Two groups, each containing 100 patients, were studied. Group A underwent elective, and group B underwent incarcerated and urgent external hernia repair. We observed high fibrinogen and WBC levels but low MPV and PDW values for patients in group B. Contrary to our expectations, we found lower MPV and PDW values in the complicated group than in the elective group. The morbidity rate and cost burden were higher in group B, and the results were statistically significant. Early operation should be recommended for patients with incarcerated external hernias if their fibrinogen and WBC levels are high.Key words: Incarcerated external hernia, Fibrinogen, Complete blood countExternal strangulated hernia is one of the most common causes of intestinal obstruction especially in the elderly. Delay in treatment may be dangerous.1 Andrews found that the need of bowel resection rate was 27% and the mortality rate was 21% when diagnosis was delayed more than 48 hours; whereas these rates were 7% and 1.4% when diagnosis was obtained in the first 24 hours.2 In addition to increased morbidity and mortality rates, a delay in the treatment of strangulated external hernias is associated with extended hospital stays and an increased need for intensive care, thereby resulting in increased health costs. Of course, clinical signs and symptoms are the most important evidences in diagnosis of incarcerated hernias. In order to make correct diagnosis, we also have powerful weapons such as radiologic imaging methods. However, these clinical and radiologic evidences show complications, especially intestinal perforation due to incarceration. Awareness of probable complications is essential. In this regard, we sometimes need simple methods to alert us. The white blood count (WBC), mean platelet volume (MPV), platelet distribution width (PDW), and blood fibrinogen level have been shown to be valuable predictive parameters for ischemic events in different parts of the body.39 There are probable ischemic tissues and organs in incarcerated hernia sac. So, in this study, we aimed to investigate the effectiveness of these simple blood tests in diagnosis. Generally, there is no problem in diagnosis, but sometimes the delay in treatment results in additional morbidity such as a need for bowel resection.  相似文献   
90.
Many techniques are described for the ligation of a difficult cystic duct (CD). The aim of this study is to assess the effectiveness and safety of stapling of a difficult CD in acute cholecystitis using Endo-GIA. From January 2008 to June 2012, 1441 patients with cholelithiasis underwent laparoscopic cholecystectomy (LC) at the Department of General Surgery, Haydarpasa Numune Education and Research Hospital. Of these, 19 (0.62%) were identified as having a difficult CD and were ligated using an Endo-GIA stapler. All patients were successfully treated with a laparoscopic approach. The length of hospital stay was 3.4 days. There were umbilical wound infections in 4 patients (21%). The length of follow-up ranged from 1.0 to 50.4 months. In conclusion, Endo-GIA is a safe and easy treatment method for patients with a dilated and difficult CD. The cystic artery should be isolated and ligated if possible before firing the Endo-GIA stapler. If isolation and stapling are not possible, fibrin sealant can be applied to avoid bleeding. The vascular Endo-GIA can be applied in a large CD, but for acute cholecystitis with an edematous CD, the Endo-GIA roticulator 4.8 or 3.5 stapler is preferred.Key words: Cholecystectomy, Endo-GIA, Acute cholecystitis, StaplerAfter the introduction of laparoscopic cholecystectomy (LC) in 1987,1 LC replaced open cholecystectomy as the gold standard for the treatment of cholelithiasis in international guidelines.2 LC was initially considered to be contraindicated for acute gallbladder inflammation, but it is currently a common procedure for acute cholecystitis.Some of the difficult situations a surgeon is likely to face during the performance of a laparoscopic cholecystectomy include anatomic anomalies such as a sessile gallbladder or short cystic duct and pathologic entities such as an empyema, Mirizzi syndrome, or a frozen Calot''s triangle secondary to infection and fibrosis.3It is suggested that laparoscopic surgery should be carried out within 72 hours from the onset of the symptoms because after that time there are higher rates of conversion to open procedures, increased risks of complications, and longer operative times.46 The generally accepted procedure in patients whose symptoms started 72 hours before admission is to “cool down” the patient with appropriate medical therapy and to perform LC after a period of 6 to 12 weeks.7,8 This approach aims to avoid a potentially more difficult cholecystectomy during an emergency admission and to avoid the difficulties of access to an emergency room.9,10 However, more than 20% of patients may fail to respond to conservative treatment and require an urgent and rather more difficult cholecystectomy, and a further 25% of patients will require readmission with a severe acute complication of cholelithiasis while awaiting a cholecystectomy.11,12 The scar formation, distortion, and organized adhesions around the gallbladder occurring secondary to the chronic inflammation in Calot''s triangle make the dissection difficult. The cystic duct (CD) is sometimes edematous, fibrous, or enlarged owing to inflammation and adhesions in acute cholecystitis and may be difficult to manage. Several methods were proposed for ligating the CD, including titanium or absorbable endoclip, endoloop, tie, ultrasonic or bipolar sealer, and the Endo-GIA stapler (Covidien, Mansfield, Massachusetts).1319This study proposes an effective, safe, and easy procedure for the stapling of dilated or difficult CD using the Endo-GIA.  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