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   1210篇
  免费   95篇
  国内免费   8篇
耳鼻咽喉   9篇
儿科学   69篇
妇产科学   35篇
基础医学   174篇
口腔科学   18篇
临床医学   106篇
内科学   328篇
皮肤病学   26篇
神经病学   95篇
特种医学   16篇
外科学   89篇
综合类   10篇
预防医学   119篇
眼科学   23篇
药学   118篇
中国医学   8篇
肿瘤学   70篇
  2023年   21篇
  2022年   12篇
  2021年   156篇
  2020年   54篇
  2019年   67篇
  2018年   74篇
  2017年   45篇
  2016年   54篇
  2015年   62篇
  2014年   52篇
  2013年   75篇
  2012年   109篇
  2011年   124篇
  2010年   43篇
  2009年   30篇
  2008年   54篇
  2007年   70篇
  2006年   40篇
  2005年   41篇
  2004年   39篇
  2003年   30篇
  2002年   30篇
  2001年   1篇
  1999年   3篇
  1998年   4篇
  1997年   4篇
  1996年   1篇
  1993年   2篇
  1989年   2篇
  1988年   1篇
  1986年   1篇
  1985年   1篇
  1984年   2篇
  1981年   2篇
  1980年   1篇
  1978年   2篇
  1977年   1篇
  1975年   2篇
  1973年   1篇
排序方式: 共有1313条查询结果,搜索用时 31 毫秒
1.
2.
Hepatocellular carcinoma (HCC) is the most frequent primary liver cancer and presents together with cirrhosis in most cases. In addition to commonly recognized risk factors for HCC development, such as hepatitis B virus/hepatitis C virus infection, age and alcohol/tobacco consumption, there are nutritional risk factors also related to HCC development including high intake of saturated fats derived from red meat, type of cooking (generation of heterocyclic amines) and contamination of foods with aflatoxins. On the contrary, protective nutritional factors include diets rich in fiber, fruits and vegetables, n-3 polyunsaturated fatty acids and coffee. While the patient is being evaluated for staging and treatment of HCC, special attention should be paid to nutritional support, including proper nutritional assessment and therapy by a multidisciplinary team. It must be considered that these patients usually develop HCC on top of long-lasting cirrhosis, and therefore they could present with severe malnutrition. Cirrhosis-related complications should be properly addressed and considered for nutritional care. In addition to traditional methods, functional testing, phase angle and computed tomography scan derived skeletal muscle index-L3 are among the most useful tools for nutritional assessment. Nutritional therapy should be centered on providing enough energy and protein to manage the increased requirements of both cirrhosis and cancer. Supplementation with branched-chain amino acids is also recommended as it improves response to treatment, nutritional status and survival, and finally physical exercise must be encouraged and adapted to individual needs.  相似文献   
3.
Uvea     
  相似文献   
4.
OBJECTIVE: The primary goal of this study was to evaluate the validity of the North American-European Consensus Committee (NAECC) definition for acute respiratory distress syndrome (ARDS) in pediatric patients. A secondary aim was to evaluate the threshold value for the PaO2/FiO2 ratio, used to determine which pediatric patients have ARDS. DESIGN: Retrospective cohort study. SETTING: Pediatric intensive care unit. PATIENTS: Pediatric intensive care unit patients who required mechanical ventilation, died, and underwent autopsy between January 1, 1996, and December 31, 2002 (n = 34). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Clinical and chest radiograph information was collected retrospectively through chart review using a standardized data collection tool. Data included the criteria specified in the NAECC definition of ARDS and demographic information. We calculated the sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratio of clinical diagnosis of ARDS compared with a pathologic diagnosis. The threshold value of PaO2/FiO2 was identified by plotting receiver operating characteristics curves and comparing the areas under the curves. The NAECC definition yielded a sensitivity of 80.7% (95% confidence interval 60-92%), specificity of 71.4% (95% confidence interval 30-95), positive predictive value of 91.3% (95% confidence interval 70-98), negative predictive value of 50.0% (95% confidence interval 20-78), and likelihood ratio of 2.82. A PaO2/FiO2 <150 had a slightly higher (but not significantly different) specificity for ARDS than a value >200 (71% vs. 86%, p = .15) without changing sensitivity. CONCLUSIONS: Our study suggests the need for further research with larger number of children to identify an optimal Pao2/Fio2 threshold for identifying ARDS in this population.  相似文献   
5.
OBJECTIVE: Breast-feeding is associated with better child development outcomes, but uncertainty remains primarily due to the close relationship between breast-feeding and socioeconomic status. This study assesses the issue in a low socioeconomic status sample where breast-feeding was close to universal. METHODS: Seven hundred eighty-four Chilean children were followed longitudinally from infancy. All but four were initially breastfed, 40% nursed beyond 12 months, and infant growth was normal. Child development was assessed at 5(1/2) years by a cognitive, language, and motor test battery. The duration of breast-feeding as the sole milk source was analyzed as a continuous variable, adjusting for a comprehensive set of background factors. RESULTS: The relationship between breast-feeding and most 5(1/2)-year developmental outcomes was nonlinear, with poorer outcome for periods of breast-feeding as the sole milk source for <2 months or >8 months--statistically significant for language, motor, and one comprehensive cognitive test, with a suggestive trend for IQ. CONCLUSIONS: The observed nonlinear relationships showed that breast-feeding as the sole milk source for <2 months or >8 months, compared with 2-8 months, was associated with poorer development in this sample. The latter finding requires replication in other samples where long breast-feeding is common and socioeconomic status is relatively homogeneous.  相似文献   
6.
Computarized tomography allows proper identification and evaluation of stage in the majority patients with periampullary tumors. However, 30% of peritoneal metastases cannot be seen in image studies. The aim of the present study was to evaluate the role of laparoscopy with laparoscopic ultrasound in the staging process of pancreatic and ampullary tumor. Diagnostic laparoscopy was performed on 20 patients included in the study Mean age was 58.35 +/- 13.4 years. Twelve were males and eight females. In two patients, laparoscopy showed peritoneal metastases and ultrasound did not show extrapancreatic involvement. In five patients, there was vascular invasion without metastases. In three patients, both peritoneal metastases and vascular invasion were found, and in five there was neither vascular invasion nor metastasis. Laparoscopic findings were confirmed in a but one patient. In 14 of the 16 patients In whom peritoneal lavage was performed, microscopic exam showed a sufficient number of cells to make a diagnosis. We concluded that laparoscopy with ultrasound is useful in staging of patients with duodeno-bilio-pancreatic malignancies.  相似文献   
7.
Patients with end-stage kidney disease, treated with renal transplantation, are at increased risk of cardio-vascular disease (CVD) and cardio-vascular mortality. They are also characterized by an atherogenic dyslipidemia. Alterations of the fatty acids (FA) profile contribute to increased cardio-vascular risk in the general population. In the current study we test the hypothesis that kidney transplantation is associated with ab-normalities in FA profile. FA profile was analysed by gas chromatography–mass spectrometry in 198 renal transplant recipients, and 48 control subjects. The most profound differences between renal transplant patients and controls were related to the content of branched chain FA, monounsaturated FA, and n-6 polyunsaturated FA, respectively. The FA profile significantly separated the patients from the controls in the principal component analysis (PCA). The abnormalities of FA profile showed a tendency for normalization in long-term kidney recipients, as compared to patients with recent transplants. The n-3 PUFA content demonstrated a strong inverse association with the presence of inflammation. Most profound alterations of the FA profile were observed in patients with impaired graft function (glomerular filtration rate < 45 mL/min). The study demonstrated significant disorders of the FA profile in kidney transplant recipients, that might contribute to cardio-vascular risk in this vulnerable patient population.  相似文献   
8.
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   
9.
Zika virus, influenza, and Ebola have called attention to the ways in which infectious disease outbreaks can severely – and at times uniquely – affect the health interests of pregnant women and their offspring. These examples also highlight the critical need to proactively consider pregnant women and their offspring in vaccine research and response efforts to combat emerging and re-emerging infectious diseases. Historically, pregnant women and their offspring have been largely excluded from research agendas and investment strategies for vaccines against epidemic threats, which in turn can lead to exclusion from future vaccine campaigns amidst outbreaks. This state of affairs is profoundly unjust to pregnant women and their offspring, and deeply problematic from the standpoint of public health. To ensure that the needs of pregnant women and their offspring are fairly addressed, new approaches to public health preparedness, vaccine research and development, and vaccine delivery are required. This Guidance offers 22 concrete recommendations that provide a roadmap for the ethically responsible, socially just, and respectful inclusion of the interests of pregnant women in the development and deployment of vaccines against emerging pathogens. The Guidance was developed by the Pregnancy Research Ethics for Vaccines, Epidemics, and New Technologies (PREVENT) Working Group – a multidisciplinary, international team of 17 experts specializing in bioethics, maternal immunization, maternal-fetal medicine, obstetrics, pediatrics, philosophy, public health, and vaccine research and policy – in consultation with a variety of external experts and stakeholders.  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