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   4315篇
  免费   177篇
  国内免费   23篇
耳鼻咽喉   217篇
儿科学   119篇
妇产科学   124篇
基础医学   501篇
口腔科学   16篇
临床医学   342篇
内科学   1229篇
皮肤病学   70篇
神经病学   358篇
特种医学   81篇
外科学   455篇
综合类   34篇
一般理论   2篇
预防医学   231篇
眼科学   122篇
药学   405篇
中国医学   2篇
肿瘤学   207篇
  2023年   25篇
  2022年   144篇
  2021年   249篇
  2020年   70篇
  2019年   91篇
  2018年   128篇
  2017年   97篇
  2016年   85篇
  2015年   95篇
  2014年   140篇
  2013年   215篇
  2012年   327篇
  2011年   378篇
  2010年   178篇
  2009年   135篇
  2008年   262篇
  2007年   291篇
  2006年   301篇
  2005年   303篇
  2004年   281篇
  2003年   240篇
  2002年   216篇
  2001年   21篇
  2000年   19篇
  1999年   14篇
  1998年   23篇
  1997年   15篇
  1996年   14篇
  1995年   8篇
  1994年   14篇
  1993年   11篇
  1992年   11篇
  1991年   10篇
  1990年   5篇
  1989年   8篇
  1988年   6篇
  1987年   6篇
  1986年   7篇
  1985年   8篇
  1984年   5篇
  1983年   6篇
  1982年   9篇
  1980年   6篇
  1978年   5篇
  1977年   9篇
  1975年   3篇
  1971年   2篇
  1967年   2篇
  1966年   2篇
  1961年   2篇
排序方式: 共有4515条查询结果,搜索用时 31 毫秒
31.
Botanicals in Postmenopausal Osteoporosis   总被引:1,自引:0,他引:1  
Osteoporosis is a systemic bone disease characterized by reduced bone mass and the deterioration of bone microarchitecture leading to bone fragility and an increased risk of fractures. Conventional anti-osteoporotic pharmaceutics are effective in the treatment and prophylaxis of osteoporosis, however they are associated with various side effects that push many women into seeking botanicals as an alternative therapy. Traditional folk medicine is a rich source of bioactive compounds waiting for discovery and investigation that might be used in those patients, and therefore botanicals have recently received increasing attention. The aim of this review of literature is to present the comprehensive information about plant-derived compounds that might be used to maintain bone health in perimenopausal and postmenopausal females.  相似文献   
32.
The occurrence of childhood obesity is influenced by both genetic and epigenetic factors. FTO (FTO alpha-ketoglutarate dependent dioxygenase) is a gene of well-established connection with adiposity, while a protooncogene PLAG1 (PLAG1 zinc finger) has been only recently linked to this condition. We performed a cross-sectional study on a cohort of 16 obese (aged 6.6–17.7) and 10 healthy (aged 11.4–16.9) children. The aim was to evaluate the relationship between methylation and expression of the aforementioned genes and the presence of obesity as well as alterations in anthropometric measurements (including waist circumference (WC), body fat (BF_kg) and body fat percent (BF_%)), metabolic parameters (lipid profile, blood glucose and insulin levels, presence of insulin resistance) and blood pressure. Expression and methylation were measured in peripheral blood mononuclear cells using a microarray technique and a method based on restriction enzymes, respectively. Multiple regression models were constructed to adjust for the possible influence of age and sex on the investigated associations. We showed significantly increased expression of the FTO gene in obese children and in patients with documented insulin resistance. Higher FTO expression was also associated with an increase in WC, BF_kg, and BF_% as well as higher fasting concentration of free fatty acids (FFA). FTO methylation correlated positively with WC and BF_kg. Increase in PLAG1 expression was associated with higher BF%. Our results indicate that the FTO gene is likely to play an important role in the development of childhood adiposity together with coexisting impairment of glucose-lipid metabolism.  相似文献   
33.
BackgroundThe aim of this study was to assess the analgesic efficacy of sufentanil in dressings after surgical treatment of burn wounds.Patients and methodsTwenty adult patients, who underwent surgical treatment of third–degree burn wounds under general anesthesia, were included. Two of the patients underwent surgery twice. During surgery, patients received 50–100 μg fentanyl every 20–30 min and, after surgery, patients received 100 mg ketoprofen twice daily. Additionally, ten patients (group 1) received 50 μg sufentanil added to the burn wound dressings soaked in octenidine and phenoxyethanol while 10 patients (group 2) received 25 μg sufentanil added to the same dressings. The rescue analgesic, which was administered when pain intensified, was 5 mg subcutaneous morphine. Plasma sufentanil concentrations were assayed at 1, 2, 3, and 6 h after surgery completion and when pain was reported, along with pain intensity evaluation.ResultsSufentanil was not detected in the serum of any patients. Rescue morphine was given during the postoperative period (24 h) in one patient in group 1 (who underwent surgery twice) and three patients in group 2. The mean sufentanil concentration in dressings was higher in group 1 (0.13 ± 0.03) than group 2 (0.06 ± 0.03 μg/mL; p < 0.001). The group 1 patient who received rescue morphine had a sufentanil concentration of 0.10 μg/mL, which was the lowest concentration in group 1. Group 2 patients who received rescue morphine had sufentanil concentrations of at least two–fold lower (0.03–0.05 μg/mL). No adverse effects were observed.ConclusionsSufentanil in dressings after burn wound surgery provides effective and safe analgesia and the sufentanil concentration in dressings should be ≥0.10 μg/mL in a solution of octenidine and phenoxyethanol.  相似文献   
34.
35.
High-risk combinations of recipient and graft characteristics are poorly defined for liver retransplantation (reLT) in the current era. We aimed to develop a risk model for survival after reLT using data from the European Liver Transplantation Registry, followed by internal and external validation. From 2006 to 2016, 85 067 liver transplants were recorded, including 5581 reLTs (6.6%). The final model included seven predictors of graft survival: recipient age, model for end-stage liver disease score, indication for reLT, recipient hospitalization, time between primary liver transplantation and reLT, donor age, and cold ischemia time. By assigning points to each variable in proportion to their hazard ratio, a simplified risk score was created ranging 0–10. Low-risk (0–3), medium-risk (4–5), and high-risk (6–10) groups were identified with significantly different 5-year survival rates ranging 56.9% (95% CI 52.8–60.7%), 46.3% (95% CI 41.1–51.4%), and 32.1% (95% CI 23.5–41.0%), respectively (< 0.001). External validation showed that the expected survival rates were closely aligned with the observed mortality probabilities. The Retransplantation Risk Score identifies high-risk combinations of recipient- and graft-related factors prognostic for long-term graft survival after reLT. This tool may serve as a guidance for clinical decision-making on liver acceptance for reLT.  相似文献   
36.
Full-left-full-right split liver transplantation (FSLT) for adult recipients, may increase the availability of liver grafts, reduce waitlist time, and benefit recipients with below-average body weight. However, FSLT may lead to impaired graft and patient survival. This study aims to assess outcomes after FSLT. Five databases were searched to identify studies concerning FSLT. Incidences of complications, graft- and patient survival were assessed. Discrete data were pooled with random-effect models. Graft and patient survival after FSLT were compared with whole liver transplantation (WLT) according to the inverse variance method. Vascular complications were reported in 25/273 patients after FSLT (Pooled proportion: 6.9%, 95%CI: 3.1–10.7%, I2: 36%). Biliary complications were reported in 84/308 patients after FSLT (Pooled proportion: 25.6%, 95%CI: 19–32%, I2: 44%). Pooled proportions of graft and patient survival after 3 years follow-up were 72.8% (95%CI: 67.2–78.5, = 231) and 77.3% (95%CI: 66.7–85.8, = 331), respectively. Compared with WLT, FSLT was associated with increased graft loss (pooled HR: 2.12, 95%CI: 1.24–3.61, = 0.006, = 189) and patient mortality (pooled HR: 1.81, 95%CI: 1.17–2.81, = 0.008, = 289). FSLT was associated with high incidences of vascular and biliary complications. Nevertheless, long-term patient and graft survival appear acceptable and justify transplant benefit in selected patients.  相似文献   
37.
Aim: The aim of the study was to investigate whether salivary mineral content may be associated with bone status in women after menopause. Material and methods: The study group consisted of 125 postmenopausal women aged 64.3 ± 6.9 yr, derived from the epidemiological SilesiaOsteoActive Study. All participants underwent hip and spine bone densitometry using dual energy X-ray absorptiometry, dental examination, and saliva content analysis. Data for salivary pH, copper, calcium, phosphorus, and zinc concentrations were evaluated. Results: Mean femoral neck bone mineral density (BMD) was 0.739 ± 0.118 g/cm2, total hip BMD 0.891 ± 0.14 g/cm2, and spine BMD 0.868 ± 0.14 g/cm2. Salivary pH was significantly lower in women with spinal osteoporosis defined as T-score below ?2.5, compared to individuals with normal BMD (pH: 6.65 ± 0.67 vs 6.96 ± 0.58, p < 0.05). There was a significant though weak inverse correlation between Ca concentration in saliva and femoral neck BMD (r = ?0.23, p < 0.05). Conclusions: High salivary calcium content and low salivary pH may be indicative of low hip and decreased spine BMD, respectively. These associations may reflect demineralization process (calcium redistribution) influencing bone, and a negative effect of acidity on mineral tissues, although causal pathway remains not clear.  相似文献   
38.
Adipose tissue yields adult adipose stem cells (ASCs) in large quantities via less-invasive methods. These cells are of interest owing to their modulating properties and paracrine activities, which can be harnessed in regenerative medicine. Many studies on the use of rat fat tissue in an autologous animal model have been conducted; however, the different locations to obtain stromal vascular fraction of rat fat depots have not been fully characterized. The purpose of the current study was to identify optimal source of ASC from various locations of rat body. Animal experiments in vitro revealed that fat depots from cervical fat are an optimal ASC source. A high ASC yield facilitates subsequent studies on autologous transplantation in rats. The secondary objective was to compare the efficiency of osteoinductive media composition and evaluate of osteogenic potential of ASCs for seeding on scaffolds for bone repair. Scaffolds were assessed in vitro, using rat adipose stem cells and three-dimensional (3D) scaffolds comprising polycaprolactone (PCL) or polycaprolactone covered with tricalcium phosphate (PCL + 5%TCP). Seeded ASCs adhere to the surface and migrate to the scaffolds. Upon staining and determining alkaline phosphatase levels, PCL + 5%TCP scaffolds performed better than PCL scaffolds. Furthermore, growth factors such as BMP2 and FGF2 significantly increased ASC mineralization and induced osteogenesis (p?<?0.05). Our results may help select and develop pre-clinical animal model for confirming the use of ASC, alone or in association with appropriate biomaterials for bone repair.  相似文献   
39.
A study of 73 patients who underwent reoperation for persistent or new complaints following initial lumbar discectomy is presented. 32 patients showed true recurrence of disc herniation (6 on the contralateral side) and 41 at a different level. 14 patients needed 3rd operation. Final results were evaluated using the Functional Economic Rating Scale elaborated by Prolo. Mean score for group operated on twice was 8.1 according to Prolo and 7.1 for group operated on 3 times.  相似文献   
40.
Fluorine and lead were determined by spectroscopic methods in some vegetables harvested in 1988 in two groups of Employees' Gardens in Inowroc?aw ("Transportowiec" and "Irena", distant from the Household Glassworks "Irena" by ca. 500 and 2600 m, respectively). Employees' Gardens "Irena" were divided into 2 belts, in consideration of a vicinal traffic artery. It was found that 42% of the plants harvested in Employees' Gardens "Transportowiec" exhibited excessive contents of fluorine, and 91%--of lead; fluorine contamination of vegetables was, however, slight, except for parsley leaves containing 56.0 mg F per 1 kg dry weight. In the case of Employees' Gardens "Irena", in the I belt (30-40 m from the traffic artery) the level of fluorine was excessive in 8.3% of plants, and that of lead--in 63.6% of plants; in the II belt (80-100 m from the traffic artery) the respective values were 17% for fluorine and 66.6% for lead.  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