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   1952篇
  免费   64篇
  国内免费   79篇
耳鼻咽喉   12篇
儿科学   85篇
妇产科学   42篇
基础医学   152篇
口腔科学   40篇
临床医学   192篇
内科学   474篇
皮肤病学   49篇
神经病学   78篇
特种医学   265篇
外科学   377篇
综合类   34篇
预防医学   119篇
眼科学   28篇
药学   77篇
中国医学   11篇
肿瘤学   60篇
  2023年   13篇
  2022年   10篇
  2021年   29篇
  2020年   15篇
  2019年   36篇
  2018年   50篇
  2017年   18篇
  2016年   34篇
  2015年   34篇
  2014年   33篇
  2013年   52篇
  2012年   64篇
  2011年   75篇
  2010年   89篇
  2009年   89篇
  2008年   55篇
  2007年   116篇
  2006年   78篇
  2005年   81篇
  2004年   54篇
  2003年   61篇
  2002年   43篇
  2001年   47篇
  2000年   59篇
  1999年   32篇
  1998年   83篇
  1997年   75篇
  1996年   64篇
  1995年   56篇
  1994年   49篇
  1993年   46篇
  1992年   33篇
  1991年   24篇
  1990年   30篇
  1989年   46篇
  1988年   41篇
  1987年   36篇
  1986年   33篇
  1985年   28篇
  1984年   25篇
  1983年   14篇
  1982年   19篇
  1981年   12篇
  1980年   13篇
  1979年   16篇
  1978年   7篇
  1977年   19篇
  1976年   13篇
  1975年   13篇
  1968年   5篇
排序方式: 共有2095条查询结果,搜索用时 0 毫秒
31.
32.
To determine the prevalence of thyroid hormone abnormalities and generalized resistance to thyroid hormone in a population of children with attention deficit hyperactivity disorder (ADHD) as compared to reference ranges determined from a control population and hence to determine if routine thyroid hormone screening in children with non-familial ADHD is indicated.

Method:


Children attending the State Child Development Centre in Perth, Western Australia with ADHD, as defined by the Diagnostic and Statistical Manual of Mental Disorders (fourth edition) provided the study population. The control population consisted of 353 normal children with a history of allergy in whom radioallergosorbent (RAST) testing was being performed.

Results:


The prevalence of thyroid hormone abnormalities in the study population was 2.3% (95% CI 0.6%, 5.7%). There were no cases of generalized resistance to thyroid hormone. The prevalence of thyroid hormone abnormalities in the general population of children and adolescents has been reported to vary between 1 and 3.7%.

Conclusion:


Routine thyroid hormone screening is not indicated in children with non-familial ADHD.  相似文献   
33.
Auricular infections caused by high ear piercing in adolescents   总被引:1,自引:0,他引:1  
  相似文献   
34.
Since the development of coronary heart disease (CAD) is affected by a specific pattern of plasma high density lipoprotein (HDL) effects it may be useful to know whether this occurs already in childhood. In this study we evaluated particle size distribution of HDL by gradient gel electrophoresis and the determination of cholesterol esterification rate (FERHDL) in plasma depleted of apo B lipoproteins in 221 children (108 boys and 113 girls) aged 4 months to 20 years. Total plasma- (TC), low-density lipoprotein- (LDL-C) and HDL- (HDL-C) cholesterol, HDL unesterified cholesterol (HDL-UC) and plasma triglycerides (TG) were also measured. There were no significant gender and age differences with respect to the plasma TC, LDL-TC and TG but concentration of HDL-TC increased with age. Post-pubertal girls had significantly higher relative concentrations of HDL2b compared to boys (30.4% vs 17.2%), while HDL3b,c was lower in post-pubertal girls (8.7% vs. 16.5 %). FERHDL correlated inversely with HDL2b and positively with HDL3b,c particles and was significantly higher in boys of the post-pubertal group compared to girls (16.9%/h vs 12.5%/h). While in girls there was a positive correlation between age and HDL-C, HDL-UC and the relative concentration of HDL2b no significant correlation were observed in boys. In girls the increase in TC showed a significant correlation with a simultaneous increase in HDL-C, HDL-UC and HDL2b. In boys TC correlated significantly with changes in TG only. When HDL2b and HDL3b,c cholesterol levels are calculated from HDL-C concentration and per cent distribution the differences between males and females are further emphasized. These data indicate that HDL particle size distribution is age- and gender-dependent.  相似文献   
35.
Persistent hyperinsulinemic hypoglycaemia of infancy (PHHI) is the most frequent cause of hypoglycaemia in infancy. Clinical presentation is heterogeneous, with variable onset of hypoglycaemia and response to diazoxide, and presence of sporadic or familial forms. Underlying histopathological lesions can be focal or diffuse. Focal lesions are characterised by focal hyperplasia of pancreatic islet-like cells, whereas diffuse lesions implicate the whole pancreas. The distinction between the two forms is important because surgical treatment and genetic counselling are radically different. Focal lesions correspond to somatic defects which are totally cured by limited pancreatic resection, whereas diffuse lesions require a subtotal pancreatectomy exposing to high risk of diabetes mellitus. Diffuse lesions are due to functional abnormalities involving several genes and different transmission forms. Recessively inherited PHHI have been attributed to homozygote mutations for the beta-cell sulfonylurea receptor (SUR1) or the inward-rectifying potassium-channel (Kir6.2) genes. Dominantly inherited PHHI can implicate the glucokinase gene, particularly when PHHI is associated with diabetes, the glutamate dehydrogenase gene when hyperammonaemia is associated, or another locus.  相似文献   
36.
37.
The aims were to determine the median survival and prognostic factors of patients with central nervous system (CNS) metastases managed with whole‐brain radiation therapy (WBRT), and to explore selection criteria in recently published clinical trials using aggressive interventions in CNS metastases. A retrospective audit was performed on patients managed with WBRT for CNS metastases. Potential prognostic factors were recorded and analysed for their association with survival duration. The proportion of patients with these factors was also compared with those of patients managed under three recently reported studies investigating aggressive interventions, such as radiosurgery and chemotherapy for CNS metastases. Seventy‐three patients were treated with WBRT for cerebral metastases over a 12‐month period. The median survival of the population was 3.4 months (95% confidence interval: 2.7–4.1), with 6‐ and 12‐month survival rates of 30 and 18%, respectively. Significant prognostic factors for prolonged median survival were Eastern Cooperative Oncology Group status 0–2 (P = 0.015), Medical Research Council neurological functional status 0–1 (P = 0.006), and Recursive Partitioning Analysis Class 2 versus Class 3 (P = 0.020). On multivariate analysis, younger patient age (P = 0.02) and better performance status (P < 0.01) were associated with improved outcome. When comparing these characteristics with selected published studies, our study cohort demonstrated a higher proportion of patients with poor performance status, a greater number of metastases per patient and a higher incidence of extracranial disease. This reflects the selected nature of patients in these published studies. Central nervous system metastases confer a poor prognosis and, for the majority of patients, aggressive interventions are unlikely to improve survival. The use of potentially toxic and expensive treatments should be reserved for those few in whom these studies have shown a potential benefit.  相似文献   
38.
39.
异一枝蒿酮酸的结构   总被引:3,自引:0,他引:3  
从新疆一枝蒿(Artemisia rupestris L.)中分得一个新成分,命名为异一枝蒿酮酸(isorupestonic acid),根据光谱(IR,UV,MS.NMR),X-ray晶体衍射及CD谱分析,确定其结构及绝对构型。并经X-ray晶体衍射及CD谱分析修正了一枝蒿酮酸的绝对构型。  相似文献   
40.
BackgroundThe coronavirus disease 2019 (COVID-19) pandemic has affected care for diseases like cancer. The aim was to evaluate the impact of COVID-19 on waiting times for diagnosis and treatment of prostate cancer (PC), as well as the possible effect on the treatment results in PC patients undergoing radical prostatectomy.MethodsWe compared the results of 497 patients who underwent biopsy prior to the COVID-19 pandemic (1 January–31 December 2019) with those of 290 patients biopsied during the COVID-19 pandemic (1 January–31 December 2020). Demographic data, tumour characteristics, type of treatment and diagnosis times were comparable. Prostate specific antigen (PSA) levels were recorded at consultation prior to biopsy and after treatment. Mann-Whitney and chi-square tests were used to compare continuous variables and percentages, respectively.ResultsIn 2020, there were fewer urology consultations (35,160 vs. 40,225 in 2019). The median PSA in 2020 was significantly higher (14.3 vs. 9.9 ng/dL in 2019). In 2019, 53.1% (N=264) of the biopsies were positive for cancer vs. 47.2% (N=137) in 2020 (P=0.104). In 2020, more patients presented with metastatic disease (7.3% vs. 1.9%, P=0.009). Also, in 2020 there was a longer waiting time for prostate biopsy (42.1 vs. 35.3 days in 2019, P=0.019). A total of 132 patients underwent laparoscopic radical prostatectomy (LARP). The median time until surgery was similar in both years (71.9 vs. 58.29 days). During 2020, a higher percentage of patients had ISUP grade 4 in the surgical specimen (34.3% vs. 17.5%, P=0.07). Furthermore, a higher percentage of aggressive (pT3) tumours were diagnosed (37.2% vs. 27.2%, P=0.08), and the percentage of patients with involvement of surgical margins was also higher (48.6% vs. 29.3%, P=0.027). There were no differences between the groups in terms of biochemical recurrence or persistent PSA at one year (P=0.711).ConclusionsDelayed biopsy during the COVID-19 period did not appear to adversely impact biopsy results. Patients biopsied in 2020 had higher PSA, possibly due to proper triaging. A higher rate of adverse pathology outcomes was observed in patients undergoing radical prostatectomy during the pandemic, probably due to understaging of the biopsy. This study serves to raise awareness of the risk of deterioration of care of PC patients due to possible underdiagnosis.  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