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   2727篇
  免费   127篇
  国内免费   24篇
耳鼻咽喉   79篇
儿科学   181篇
妇产科学   169篇
基础医学   178篇
口腔科学   161篇
临床医学   184篇
内科学   477篇
皮肤病学   58篇
神经病学   256篇
特种医学   89篇
外科学   741篇
综合类   25篇
一般理论   1篇
预防医学   46篇
眼科学   63篇
药学   81篇
肿瘤学   89篇
  2024年   2篇
  2023年   27篇
  2022年   50篇
  2021年   108篇
  2020年   78篇
  2019年   89篇
  2018年   106篇
  2017年   97篇
  2016年   126篇
  2015年   146篇
  2014年   142篇
  2013年   169篇
  2012年   230篇
  2011年   225篇
  2010年   121篇
  2009年   109篇
  2008年   169篇
  2007年   186篇
  2006年   167篇
  2005年   132篇
  2004年   99篇
  2003年   66篇
  2002年   83篇
  2001年   25篇
  2000年   31篇
  1999年   20篇
  1998年   8篇
  1997年   10篇
  1996年   6篇
  1995年   14篇
  1994年   3篇
  1993年   5篇
  1992年   8篇
  1991年   4篇
  1990年   4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
排序方式: 共有2878条查询结果,搜索用时 312 毫秒
121.
Pulmonary artery aneurysm (PAA) is a rare entity with fatal complications. Its silent course contributes to large aneurysms with compression symptoms. We present a 39-year-old female idiopathic pulmonary arterial hypertension patient with a giant PAA causing severe pulmonary regurgitation (PR) and symptomatic left main coronary artery compression (LMCA). Since she had a failed LMCA stenting attempt, she underwent surgery. A valve-sparing David-like pulmonary trunk reconstruction and coronary artery bypass were performed. This case illustrates that David-like reconstruction procedure can be applied to the PAA with severe PR.  相似文献   
122.
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   
123.
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   
124.
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   
125.

Purpose

The purpose of this study was to evaluate our clinical experience with ceramic-on-ceramic cementless total hip arthroplasty (THA) and complications after an average follow-up of more than eight years.

Methods

From January 2001 to December 2008, 540 THA with ceramic-on-ceramic bearings were performed in 448 patients (92 bilateral, 54 of which were operated simultaneously) with a mean age 49.9 years (range 18–84) by a senior surgeon. Pre-operative aetiological reasons were developmental dysplasia of the hip (DDH) in 205 hips, degenerative arthritis in 157 hips, avascular necrosis in 51 hips, rheumatoid diseases in 40 hips, posttraumatic arthritis in 40 hips, other reasons in 25 hips and revision surgery in 22 hips. Patients were evaluated with Harris hip score (HSS), and radiological findings of acetabular and femoral component loosening or osteolysis with ceramic bearing related complications like squeaking, liner and head fractures were recorded.

Result

The average duration of follow-up time was 8.2 years (range, five to 13.2). The main Harris hip score increased from 42.4 points preoperatively to 94.9 points at the time of last follow-up. We had one fracture of the ceramic head, 11 clicking and four squeaking; one of them was revised because of terrible squeaking due to acetabular liner fracture, the other three were seldom audible from the outside and followed conservatively. We did not observed loosening or osteolysis due to ceramic bearings at the time of the final follow-up.

Conclusion

Our study has demonstrated that ceramic-on-ceramic bearings can be used safely in different etiological problems. Incidences of noisy hips are becoming less frequent.  相似文献   
126.
127.
128.
129.

Background:

In subungual exostosis surgery, repair of the damaged nail bed and surgical excision of the mass without damaging the nail bed is important. The ideal method of surgery is still unclear. This study is done to qualify the effects of different surgical methods on outcome measures in different types of subungual exostosis.

Materials and Methods:

Fifteen patients, operated with a diagnosis of subungual exostosis between January 2008 and June 2012, were evaluated. Protruded masses were excised with a dorsal surgical approach after the removal of the nail bed and nonprotruded masses were excised through a“fish-mouth” type of incision.

Results:

The mean age of the patients in protruded subungual exostosis group was 17.3 years (range 13-22 years) and this group consisting of seven female and two male patients. The patients were followed up for a mean of 14.1 ± 4.8 months. The mean age of the patients in the nonprotruded subungual exostosis group was 14.6 years (range 13-16 years) and consisting of six female patients. The patients were followed up for a mean of 11.6 ± 2.9 months. The results were positively affected by changing the surgical approach depending on whether or not the exostosis is protruded from the nail bed. All patients had healthy toe nails in the postoperative period without any signs of recurrence.

Conclusions:

In patients with a protruded subungual exostosis, the mass should be removed by a dorsal approach with the removal of the nail and injury to the nail bed should be repaired. In patients with a nonprotruded subungual exostosis, the mass should be excised through a “fish-mouth” type incision at the toe tip without an iatrogenic damage.  相似文献   
130.
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   
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