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   3602篇
  免费   238篇
  国内免费   38篇
耳鼻咽喉   50篇
儿科学   126篇
妇产科学   172篇
基础医学   348篇
口腔科学   134篇
临床医学   303篇
内科学   596篇
皮肤病学   91篇
神经病学   162篇
特种医学   131篇
外国民族医学   2篇
外科学   699篇
综合类   82篇
一般理论   7篇
预防医学   261篇
眼科学   101篇
药学   360篇
中国医学   38篇
肿瘤学   215篇
  2023年   43篇
  2022年   107篇
  2021年   185篇
  2020年   122篇
  2019年   179篇
  2018年   211篇
  2017年   123篇
  2016年   141篇
  2015年   128篇
  2014年   154篇
  2013年   233篇
  2012年   287篇
  2011年   334篇
  2010年   179篇
  2009年   123篇
  2008年   198篇
  2007年   152篇
  2006年   160篇
  2005年   130篇
  2004年   130篇
  2003年   93篇
  2002年   84篇
  2001年   39篇
  2000年   16篇
  1999年   18篇
  1998年   27篇
  1997年   20篇
  1996年   15篇
  1995年   8篇
  1994年   16篇
  1993年   11篇
  1992年   18篇
  1991年   24篇
  1990年   19篇
  1989年   11篇
  1988年   7篇
  1987年   13篇
  1985年   10篇
  1984年   16篇
  1983年   7篇
  1982年   9篇
  1981年   6篇
  1980年   5篇
  1979年   4篇
  1978年   6篇
  1976年   9篇
  1974年   4篇
  1973年   4篇
  1972年   6篇
  1966年   5篇
排序方式: 共有3878条查询结果,搜索用时 31 毫秒
1.
Background and purpose — Total ankle arthroplasties (TAAs) have larger revision rates than hip and knee implants. We examined the survival rates of our primary TAAs, and what different factors, including the cause of arthritis, affect the success and/or revision rate.Patients and methods — From 2004 to 2016, 322 primary Hintegra TAAs were implanted: the 2nd generation implant from 2004 until mid-2007 and the 3rd generation from late 2007 to 2016. A Cox proportional hazards model evaluated sex, age, primary diagnosis, and implant generation, pre- and postoperative angles and implant position as risk factors for revision.Results — 60 implants (19%) were revised, the majority (n = 34) due to loosening. The 5-year survival rate (95% CI) was 75% (69–82) and the 10-year survival rate was 68% (60–77). There was a reduced risk of revision, per degree of increased postoperative medial distal tibial angle at 0.84 (0.72–0.98) and preoperative talus angle at 0.95 (0.90–1.00), indicating that varus ankles may have a larger revision rate. Generation of implant, sex, primary diagnosis, and most pre- and postoperative radiological angles did not statistically affect revision risk.Interpretation — Our revision rates are slightly above registry rates and well above those of the developer. Most were revised due to loosening; no difference was demonstrated with the 2 generations of implant used. Learning curve and a low threshold for revision could explain the high revision rate.

Arthritis in the ankle often develops earlier than in the hip or knee, and 70% have a traumatic etiology (Saltzman et al. 2005, Brown et al. 2006). Total ankle arthroplasty (TAA) can be indicated for severe arthritis in the ankle joint, but the anatomical preconditions, like a small surface area and high stress from compression and torque (Bouguecha et al. 2011, Kakkar and Siddique 2011), makes it less durable than hip and knee prosthetics. The Hintegra TAA, a 3-component mobile bearing, uncemented implant (Hintermann et al. 2004) is widely used and results from the development center demonstrate survival rates of 94% and 84% after 5 and 10 years’ follow-up (Barg et al. 2013). This is considerably more than the survival rates from national registries. Labek et al. (2011) demonstrated that development centers report only half of the revision rate that can be found in the few existing national registers. In a systematic review of primary Agility total ankle arthroplasty (DePuy Synthes Orthopedics, Warsaw, IN, USA), the author (Roukis 2012) found that the incidence of complications increased from 7% to 12%, in studies where the inventor was excluded. Similar results were found by Prissel and Roukis (2013), who found an increased incidence of complications from 6% to 13% in studies where the inventor or faculty consultants were excluded. These studies indicated the risk of selection (inventor) and publication (conflict of interest) bias.Planning and surgical technique, including significant experience, are mandatory for a successful outcome. The better result from development centers may reflect, besides the above-mentioned bias, that there is a long learning curve and that the indication for revision surgery varies.We examined the survival rates of primary Hintegra TAAs performed at Hvidovre Hospital, with revision rate as outcome. We report primary diagnosis for primary TAA and examine whether sex, generation of the implant, preoperative angles and implant position affect the revision rate.  相似文献   
2.
We study the image formation of vibro-acoustography systems based on a concave sector array transducer taking into account depth-of-field effects. The system point-spread function (PSF) is defined in terms of the acoustic emission of a point-target in response to the dynamic radiation stress of ultrasound. The PSF on the focal plane and the axis of the transducer are presented. To extend the obtained PSF to the 3D-space, we assume it is a separable function in the axial direction and the focal plane of the transducer. In this model, an image is formed through the 3D convolution of the PSF with an object function. Experimental vibro-acoustography images of a breast phantom with lesion-like inclusions were compared with simulated images. Results show that the experimental images are in good agreement with the proposed model.  相似文献   
3.
4.
The aim of this study was to evaluate the public opinion towards the possible replacement of ration cards by cash payment and to investigate the effect of partial termination of food price subsidy programme on food consumption by families from different income brackets. A purposive sample of 300 families from Alexandria Governorates were interviewed to assess the attitude of the consumer towards the possible termination of current food subsidy programme. After one year, during which the subsidy programme was reduced, a follow up sample of 240 were interviewed. The results show that a large proportion of the families prefer the continuation of the current programme (80-81.2%), meanwhile, around 90% of them believed that subsidized foods do not reach the target group. The data show that subsidized meat and poultry are consumed by high income families while frozen subsidized fish was mostly consumed by poor families. The partial termination of the subsidy programme forced the families to reduce their consumption from sugar, tea, oil, and rice. During the second phase of the study. However the results show that high income families were least affected by the partial termination of the subsidy programme.  相似文献   
5.
为了定量测试脑膜瘤WHO分级法的价值,作者应用倍体分类、增殖指数和S期细胞比率三项参数进行分析,发现这三项指标与WHO分级密切相关。脑膜瘤异形细胞、坏死、核分裂及脑浸润的出现与肿瘤WHO分级增加和肿瘤复发密切相关。这些结果特别对肿瘤的异质性和测量技术差异问题给予小心评价。  相似文献   
6.
Radioimmunoassays (RIAs) have been used to detect the promutagenic lesion O6-methyldeoxyguanosine (O6-MedG) in DNA isolated from the bladder tissues of Egyptian patients presenting with bladder carcinoma and concomitant schistosomiasis (bilharziasis), a parasitic disease known to be associated with the presence of N-nitrosamines in the urine. Alkylation damage was present in the DNA of the majority of the samples (44/46, 96%); 38 samples were of tumour tissue and 8 from uninvolved bladder mucosa. Levels of O6-MedG ranged from undetectable (ND; i.e. less than 0.01 mumol O6-MedG/mol dG) to 0.485 mumol/mol dG with an overall mean of 0.134 +/- 0.10 mumol/mol dG, including the two samples that were below the limit of detection. In contrast, methylation damage was detected in only 4/12 (33%) of the DNA samples from normal bladder tissue of European origin. In these samples levels of O6-MedG ranged from ND to 0.225 mumol/mol dG with an overall mean of 0.046 +/- 0.082 mumol O6-MedG/mol dG. These results confirm that alkylation events can be detected in the DNA of schistosome-infected human bladder tissue. The methylation of uninvolved and tumour tissue DNA to similar extents suggests that the alkylating intermediate may have been present in the urine. These results indicate the need for further investigation to determine whether relationships exist between levels of DNA damage and the prevalence of schistosome infection and/or the extent and type of bacterial infection that frequently accompanies this disease.  相似文献   
7.
Burns during pregnancy: a gloomy outcome   总被引:2,自引:0,他引:2  
The effect of burns on fetal and maternal survival is known to be detrimental. This prospective study describes the performance of pregnant burned patients who were managed and followed up for fetal and maternal outcomes at Ain Shams University's burn unit and Maternity Hospital during the period from October 1995 to September 1996. During the 12-month period, 27 pregnant burned patients were managed. Fetal and maternal mortality correlated with the total body surface area (TBSA) burned, the mortality rate being 63 per cent for both mothers and fetuses in the 25–50 per cent TBSA group. A fetal loss of 56 per cent with no maternal loss were recorded in the 15–25 per cent TBSA group. Experience in dealing with pregnant burned patients proves that early surgical excision and skin grafting, with timely termination of pregnancy are the best lines of treatment. Prevention or minimizing the effects of the burns may be achieved by proper education and guidance of the pregnant woman.  相似文献   
8.
Between 1984 and 1986 six patients with acute respiratory failure (requiring ventilation for at least 3 days) complicating acute pancreatitis were managed on the intensive care unit (median ventilation period 6 days; range 3-41 days). Between 1987 and 1989 nine similar patients were managed (median ventilation period 35 days, range 4-69 days), and a regimen of enteral tobramycin, polymyxin and amphotericin to selectively decontaminate the digestive tract (SDD) was introduced. Five of six patients treated before 1987 had serious infections (three Gram-negative, one fungal), compared with only one of nine patients treated with SDD (P < 0.05). Clinical signs of sepsis were evident for 62% of the pre-SDD period, compared with 39% of the period during SDD therapy (P < 0.001). Systemic antibiotic prescribing was reduced in the SDD group; however, mortality remained unaffected with only two patients surviving pre-SDD and three during SDD treatment. SDD reduces infection rates and sepsis in patients with acute pancreatitis and may help to improve the prognosis of this life-threatening condition.  相似文献   
9.
Carcinoma of the urinary bladder is a common malignancy in many tropical and subtropical countries. There is a well documented sequela of chronic urinary schistosomal infection and bladder cancer associated with schistosomiasis is a major cause of morbidity and mortality in the endemic areas. Experimental bladder cancer can be induced in schistosome-infected animals. Multiple factors have been suggested as causative agents in schistosome-associated bladder carcinogenesis and the N-nitroso compounds appear to be of particular importance. These agents have long been suspected to play a major role in the aetiology of a variety of human cancers. A model for the induction of bladder cancer associated with schistosomiasis is proposed which takes into account the interrelationships between different factors resulting from the infection, especially the role of alkylating agents that can contribute to the induction of this neoplasm.  相似文献   
10.
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