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   527篇
  免费   35篇
  国内免费   4篇
耳鼻咽喉   19篇
儿科学   7篇
妇产科学   5篇
基础医学   42篇
口腔科学   9篇
临床医学   40篇
内科学   99篇
皮肤病学   2篇
神经病学   30篇
特种医学   24篇
外国民族医学   1篇
外科学   140篇
综合类   17篇
预防医学   44篇
眼科学   7篇
药学   26篇
中国医学   8篇
肿瘤学   46篇
  2023年   8篇
  2022年   17篇
  2021年   18篇
  2020年   9篇
  2019年   24篇
  2018年   13篇
  2017年   13篇
  2016年   25篇
  2015年   18篇
  2014年   26篇
  2013年   38篇
  2012年   31篇
  2011年   32篇
  2010年   15篇
  2009年   16篇
  2008年   33篇
  2007年   25篇
  2006年   21篇
  2005年   24篇
  2004年   19篇
  2003年   23篇
  2002年   31篇
  2001年   20篇
  2000年   18篇
  1999年   3篇
  1998年   3篇
  1997年   4篇
  1996年   3篇
  1995年   2篇
  1994年   1篇
  1992年   3篇
  1991年   3篇
  1990年   4篇
  1989年   3篇
  1988年   3篇
  1987年   3篇
  1986年   3篇
  1985年   2篇
  1984年   2篇
  1983年   1篇
  1982年   2篇
  1979年   1篇
  1977年   1篇
  1965年   1篇
  1936年   1篇
排序方式: 共有566条查询结果,搜索用时 15 毫秒
91.
Five plants (Myrtus communis, Apium graveolens, Matricaria chamomilla, Withania somnifera and Achillea santolina) grown in Iraq were assessed for their anti-inflammatory activity on intact rats by measuring the suppression of carrageenan-induced paw edema produced by 1/10 of the intraperitoneal LD50 doses for the respective 80% ethanol extracts. Acetylsalicylic acid was used as the standard drug. Results showed that the plants possessed varying degrees of anti-inflammatory activity and were classified in the following descending order of activity: W. somnifera greater than A. graveolens greater than A. santolina greater than M. chamomilla greater than M. communis.  相似文献   
92.
International Urology and Nephrology - The Metabolic equivalent of task (MET) score is used in patients’ preoperative functional capacity assessment. It is commonly thought that patients with...  相似文献   
93.
94.
The presence of cervical lymph node metastasis in patients with head and neck cancer is associated with an unfavorable prognosis. Reports vary as to whether various conventional radiographic studies, such as computed tomography (CT) and magnetic resonance imaging, confer an advantage over physical examination in the patient without clinical findings of cervical metastasis (N0). Positron emission tomography (PET) is a functional imaging modality that has recently been used for head and neck neoplasms. The use of PET in the evaluation of the N0-staged neck in 14 consecutive patients with squamous cell carcinoma (SCC) of the upper aerodigestive tract is reported. Seven patients (50%) undergoing 13 neck dissections had pathologic evidence of disease. PET scans were positive in five patients with pathologically confirmed cervical metastasis. PET scans were negative in seven patients (11 neck dissections) with no pathologic evidence of disease. PET scans were positive for unilateral cervical metastasis in two of three patients with involvement of a single lymph node. PET scans were positive in two of three patients with more than two lymph nodes involved. PET had an accuracy of 100% in the eight patients with SCC of the oral cavity. In patients with oropharyngeal or hypopharyngeal carcinoma PET localized cervical metastasis in two of four patients with neck metastasis. In the patient with an N0-staged neck on clinical examination, PET was found to have an overall sensitivity of 78%, specificity of 100%, positive predictive value of 100%, negative predictive value of 88%, and accuracy of 92%. CT demonstrated sensitivity of 57%, specificity of 90%, positive predictive value of 80%, negative predictive value of 75%, and accuracy of 76%. PET showed a trend in increased accuracy (P= 0.11) over CT. PET appears to be a promising diagnostic aid that may be applied when evaluating the N0-staged neck, especially for SCC of the oral cavity.  相似文献   
95.
In this study, we retrospectively analysed data from 877 patients who had 1204 embryo transfer procedures following in-vitro fertilization (IVF) at Midland Fertility Services, UK, between January 1991 and December 1995 to investigate the factors contributing to failure of embryo transfer at first attempt and the impact of immediate retransfer of retained embryos on the treatment outcome. Embryos were significantly more likely to be retained when the embryo transfer catheter was contaminated with mucus (3.3 versus 17.8%, P = 0.000001) or blood (3.3 versus 12%, P = 0.00001) and when the transfer procedure was difficult compared with when it was easy (20.3 versus 0.8%, P = 0.00001). There was no significant difference in the clinical pregnancy rate between those who had all their embryos transferred at the first attempt (24.7%) and those who required more than one attempt (23.2%). The types of embryo transfer catheter used in the unit did not show any difference in terms of embryo retention. Although we recommend aspiration of cervical mucus in order to reduce the rate of retained embryos, there is no evidence from our study to suggest that pregnancy rate is compromised when embryos are retained, provided they are discovered and immediately retransferred into the uterine cavity. Immediate retransfer is more convenient to the patients and reduces the laboratory workload without compromising the treatment outcome.   相似文献   
96.
The effect of laughter therapy on the plasma levels of renin, angiotensinogen, and prorenin was investigated in patients with type 2 diabetes. In the diabetic patients, the mean plasma renin concentrations were 24.6+/-12.1 ng/ml/h in the first observation (at the beginning of laughter therapy), 8.2+/-3.4 ng/ml/h in the second observation (three months after the beginning of laughter therapy) and 7.7+/-1.7 ng/ml/h in the third observation (six months after the beginning of laughter therapy). The mean plasma angiotensinogen concentrations in the 1st, 2nd and 3rd observations were 0.19+/-0.08, 0.47+/-0.12, 0.42+/-0.14 microg/ml, respectively. The mean plasma prorenin concentrations in the 1st, 2nd and 3rd observations during the laughter therapy were 195.1+/-66.2, 193.4+/-88.2 and 170.7+/-52.5 pg/ml, respectively. Plasma renin concentrations were significantly decreased (p<0.05) by the therapy. Subnormal concentrations of plasma angiotensinogen were found in the 1st observation and increased significantly (p<0.05) to the normal range after the therapy. Plasma prorenin concentration only slightly changed during the laughter therapy. Other biochemical parameters remained unchanged during the laughter therapy. These results indicated that a long-term laughter therapy changed the plasma components of renin-angiotensin system in patients with diabetes. Thus, laughter therapy can be used as non-pharmacological treatment for the prevention of diabetic microvascular complications.  相似文献   
97.
Welding accidents have resulted in over 50 admissions to the Royal Adelaide Hospital in the last 5 years. Our attention was drawn to the significance of workplace welding accidents when a patient died from 80% burns sustained while welding an empty 44 gallon drum in 2006. Our study performed in conjunction with Workcover and Safework SA revealed that welding empty drums has caused many similar accidents resulting in significant morbidity and mortality throughout Australia each year. To date there is only one report in the literature1 referring to this issue. Welding accidents result in significant time lost to work and financial cost to society. We describe our audit of burns sustained while welding and pay particular attention to oil, petrol and diesel drum explosions. Given their potentially avoidable nature, greater public and workplace awareness must be raised to reduce the tragic consequences of these accidents.  相似文献   
98.
A role for nuclear PTEN in neuronal differentiation.   总被引:14,自引:0,他引:14  
Mutations of phosphatase and tensin homolog deleted on chromosome 10 (PTEN), a protein and lipid phosphatase, have been associated with gliomas, macrocephaly, and mental deficiencies. We have assessed PTEN's role in the nervous system and find that PTEN is expressed in mouse brain late in development, starting at approximately postnatal day 0. In adult brain, PTEN is preferentially expressed in neurons and is especially evident in Purkinje neurons, olfactory mitral neurons, and large pyramidal neurons. To analyze the function of PTEN in neuronal differentiation, we used two well established model systems-pheochromocytoma cells and cultured CNS stem cells. PTEN is expressed during neurotrophin-induced differentiation and is detected in both the nucleus and cytoplasm. Suppression of PTEN levels with antisense oligonucleotides does not block initiation of neuronal differentiation. Instead, PTEN antisense leads to death of the resulting, immature neurons, probably during neurite extension. In contrast, PTEN is not required for astrocytic differentiation. These observations indicate that PTEN acts at multiple sites in the cell, regulating the transition of differentiating neuroblasts to postmitotic neurons.  相似文献   
99.
Frequent consumption of sports and energy drinks among athletes is of concern due to its detrimental impact on oral health. The present study aimed to assess sports and energy drink consumption, oral health status and impacts on daily activities and sports performance among elite athletes from Pakistan. Data regarding socio-demographic characteristics, sports and energy drink consumption, oral health and hygiene practices, self-reported oral health and psychosocial and performance impact was assessed using a self-administered, structured questionnaire followed by clinical oral examination by a single, experienced dentist. A total of 104 athletes, a majority of whom were male (80.8%), participated in the study. Around two third of the participants reported consumption of sports and energy drinks, energy gels or bars at least once a week, the commonest being Sting. Despite good oral hygiene practices, the athletes generally had poor oral health with high prevalence of dental caries (63.5%), gingivitis (46.1%), irreversible periodontitis (26.9%) and erosive tooth wear (21.2%). More than a quarter (28.8%) of the athletes rated their oral health as fair—very poor. Four in five athletes (80%) also experienced at least one oral problem with negative impacts on daily activities (64.4%) and participation training and sports performance (36.5%). Regression analyses revealed a significant association between periodontal disease and impact on both daily activities and sports performance. To our knowledge, this is the first study reporting that high-prevalence sports and energy drink consumption and oral problems among elite athletes from Pakistan has a negative impact on daily activities and sports performance. These findings may have important implications for oral health education programs, and the need to create awareness among the athletes regarding the use of sports and energy drinks, as well as regular oral health screening of athletes to minimize the impact on performance.  相似文献   
100.
The surge in plastic waste production has forced researchers to work on practically feasible recovery processes. Pyrolysis is a promising and intriguing option for the recycling of plastic waste. Developing a model that simulates the pyrolysis of high-density polyethylene (HDPE) as the most common polymer is important in determining the impact of operational parameters on system behavior. The type and amount of primary products of pyrolysis, such as oil, gas, and waxes, can be predicted statistically using a multiple linear regression model (MLRM) in R software. To the best of our knowledge, the statistical estimation of kinetic rate constants for pyrolysis of high-density plastic through MLRM analysis using R software has never been reported in the literature. In this study, the temperature-dependent rate constants were fixed experimentally at 420 °C. The rate constants with differences of 0.02, 0.03, and 0.04 from empirically set values were analyzed for pyrolysis of HDPE using MLRM in R software. The added variable plots, scatter plots, and 3D plots demonstrated a good correlation between the dependent and predictor variables. The possible changes in the final products were also analyzed by applying a second-order differential equation solver (SODES) in MATLAB version R2020a. The outcomes of experimentally fixed-rate constants revealed an oil yield of 73% to 74%. The oil yield increased to 78% with a difference of 0.03 from the experimentally fixed rate constants, but light wax, heavy wax, and carbon black decreased. The increased oil and gas yield with reduced byproducts verifies the high significance of the conducted statistical analysis. The statistically predicted kinetic rate constants can be used to enhance the oil yield at an industrial scale.  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