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   3271篇
  免费   285篇
  国内免费   16篇
耳鼻咽喉   36篇
儿科学   58篇
妇产科学   47篇
基础医学   498篇
口腔科学   472篇
临床医学   316篇
内科学   708篇
皮肤病学   45篇
神经病学   324篇
特种医学   59篇
外科学   303篇
综合类   7篇
预防医学   122篇
眼科学   61篇
药学   171篇
中国医学   8篇
肿瘤学   337篇
  2023年   33篇
  2022年   66篇
  2021年   85篇
  2020年   67篇
  2019年   175篇
  2018年   214篇
  2017年   254篇
  2016年   72篇
  2015年   81篇
  2014年   101篇
  2013年   134篇
  2012年   219篇
  2011年   227篇
  2010年   115篇
  2009年   90篇
  2008年   168篇
  2007年   157篇
  2006年   134篇
  2005年   129篇
  2004年   106篇
  2003年   123篇
  2002年   116篇
  2001年   80篇
  2000年   81篇
  1999年   66篇
  1998年   31篇
  1997年   31篇
  1996年   35篇
  1995年   20篇
  1994年   22篇
  1993年   11篇
  1992年   35篇
  1991年   34篇
  1990年   27篇
  1989年   27篇
  1988年   22篇
  1987年   22篇
  1986年   15篇
  1985年   15篇
  1984年   12篇
  1983年   25篇
  1982年   9篇
  1979年   12篇
  1977年   5篇
  1976年   6篇
  1975年   4篇
  1974年   11篇
  1973年   13篇
  1972年   8篇
  1967年   5篇
排序方式: 共有3572条查询结果,搜索用时 15 毫秒
51.
The present study had three objectives: (a) to characterize the functional capacity of patients with PD, (b) to assess the relationship between the physical fitness components of functional capacity with clinical characteristics and disease severity, and (c) to compare the physical fitness components of functional capacity with clinical characteristics according to disease severity. The study included 54 patients with idiopathic PD who were distributed into two groups according to PD severity: unilateral group (n=35); and bilateral group (n=19). All patients underwent psychiatric assessment by means of the Hoehn and Yahr (HY) staging of PD, the Unified Parkinson's Disease Rating Scale (UPDRS), the Hospital Anxiety and Depression Scale (HADS-A and HADS-D, respectively), and The Mini-Mental State Examination (MMSE). The physical fitness components of functional capacity were evaluated over a 2-day period, using recommendations by the American Alliance for Health, Physical Education, Recreation and Dance, and the Berg Balance Scale (BBS). Pearson correlation coefficients and multiple regressions were calculated to test the correlation between functional capacity and clinical characteristics, and to predict clinical scores from physical performance, respectively. Clinical variables and physical component data were compared between groups using analysis of variance to determine the effects of disease severity. Patients with advanced disease showed low levels of functional capacity. Interestingly, patients with good functional capacity in one of the physical fitness components also showed good capacities in the other components. Disease severity is a major factor affecting functional capacity and clinical characteristics. Medical providers should take disease severity into consideration when prescribing physical activity for PD patients, since the relationship between functional capacity and clinical characteristics is dependent on disease severity.  相似文献   
52.
53.
The role of adipose tissue insulin resistance in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) remains unclear. To evaluate this, we measured in 207 patients with NAFLD (age = 51 ± 1, body mass index = 34.1 ± 0.3 kg/m(2) ) and 22 controls without NAFLD (no NAFLD) adipose tissue insulin resistance by means of a validated index (Adipo-IR(i) = plasma free fatty acids [FFA] x insulin [FPI] concentration) and as the suppression of plasma FFA during an oral glucose tolerance test and by a low-dose insulin infusion. We also explored the relationship between adipose tissue insulin resistance with metabolic and histological parameters by dividing them based on quartiles of adipose tissue insulin resistance (Adipo-IR(i) quartiles: Q1 = more sensitive; Q4 = more insulin resistant). Hepatic insulin resistance, measured as an index derived from endogenous glucose production x FPI (HIRi), and muscle insulin sensitivity, were assessed during a euglycemic insulin clamp with 3-[(3) H] glucose. Liver fat was measured by magnetic resonance imaging and spectroscopy, and a liver biopsy was performed to assess liver histology. Compared to patients without steatosis, patients with NAFLD were insulin resistant at the level of adipose tissue, liver, and skeletal muscle and had higher plasma aspartate aminotransferase and alanine aminotransferase, triglycerides, and lower high-density lipoprotein cholesterol and adiponectin levels (all P < 0.01). Metabolic parameters, hepatic insulin resistance, and liver fibrosis (but not necroinflammation) deteriorated as quartiles of adipose tissue insulin resistance worsened (all P < 0.01). CONCLUSION: Adipose tissue insulin resistance plays a key role in the development of metabolic and histological abnormalities of obese patients with NAFLD. Treatment strategies targeting adipose tissue insulin resistance (e.g., weight loss and thiazolidinediones) may be of value in this population.  相似文献   
54.
Context The biphasic ontogeny of serum gonadotrophins observed in normal children also exists in girls with gonadal dysgenesis, although with higher levels. However, limited data exist in prepubertal boys with anorchia. Objective To investigate whether the existence of testicular tissue is required for gonadotrophin downregulation in boys. Secondarily, we analysed the prevalence of high gonadotrophins and its diagnostic value to assess the presence or absence of testes in childhood. Study design In a retrospective, semi‐longitudinal study, we compared serum gonadotrophin levels in 35 boys with anorchia aged 0–18 years, in 29 bilaterally cryptorchid boys with abdominal testes and in 236 normal boys. Results In anorchid boys, follicle stimulating hormone (FSH) and luteinizing hormone (LH) were abnormally high in the first months after birth, then decreased progressively. LH decreased more readily than FSH and dropped to normal values in up to 70% of anorchid patients before the usual age of pubertal onset, when both gonadotrophins increased again to very high levels. In cryptorchid boys, FSH was elevated in a significantly (P < 0·0001) lower proportion of cases. Below the age of 6 years, FSH below 2 IU/l ruled out anorchia and LH above 5 IU/l confirmed anorchia with high accuracy. Between 6 and 11 years, FSH or LH levels above 5 IU/l were highly specific for the absence of testes. Conclusions The U‐shaped pattern of serum gonadotrophins observed in normal males from birth to puberty was also found in anorchid boys, but with gonadotrophin levels considerably elevated. Serum gonadotrophin levels may normalize in anorchid boys during late childhood only to rise again at puberty. The presence of testicular tissue results in restrain of gonadotrophin secretion in most patients, even if the testes are cryptorchid.  相似文献   
55.
The fetal lung is affected by maternal diabetes. Nuclear receptor PPARα regulates nitric oxide (NO) overproduction in different tissues. We aimed to determine whether fetal lung PPARα expression is altered by maternal diabetes, and if there are gender-dependent changes in PPARα regulation of NO production in the fetal lung. Fetal lungs from control and diabetic rats were explanted on day 21 of gestation and evaluated for PPARα expression and NO production. Fetuses were injected with the PPARα ligand LTB(4) on days 19, 20 and 21, and the fetal lung explanted on day 21 to evaluate PPARα and the inducible isoform of NO synthase (iNOS). Besides, pregnant rats were fed with olive oil- and safflower oil-supplemented diets, enriched in PPAR ligands, for evaluation of fetal lung NO production and PPARα expression. We found reduced PPARα concentrations only in the lung from male fetuses from the diabetic group when compared to controls, although maternal diabetes led to NO overproduction in both male and female fetal lungs. Fetal activation of PPARα led to changes in lung PPARα expression only in female fetuses, although this treatment increased iNOS expression in both male and female fetuses in the diabetic group. Diets supplemented with olive oil and not with safflower oil led to a reduction in NO production in male and female fetal lungs. In conclusion, there are gender-dependent changes in PPARα expression and signaling in the fetal lung from diabetic rats, although PPARα activation prevents maternal diabetes-induced lung NO overproduction in both male and female fetuses.  相似文献   
56.
Objective: To determine number, species of Candida and Candida resistance to antifungal therapy according to the metabolic control state and the associated salivary changes in patients with type 2 diabetes mellitus (DM2).

Materials and methods: Samples of non-stimulated saliva were collected from 52 patients with DM2. Salivary pH was measured and cultured on Sabouraud glucose agar and the values of CFU/ml were calculated. The species were presumptively identified using CHROMagar Candida® plates, and identification was confirmed by polymerase chain reaction (PCR). C. albicans isolates were cultured on SGA tetracycline agar with nystatin and fluconazole diffusion disks to measure susceptibility.

Results: Sixty six percent of the yeasts isolated were Candida albicans, followed by C. glabrata (20.7%). In patients with decompensated DM2, there was an inverse association between HbA1c value and salivary pH. At higher levels of salivary acidification, a greater diversity and quantity of yeasts of the genus Candida were observed. With nystatin, higher inhibition was observed at lower pH.

Conclusions: The antifungal therapies could be more effective if it consider, qualitative salivary characteristics as pH, that could determine the susceptibility of species of Candida to at least to nystatin, which is the most used antifungal for treatment to oral candidiasis in patients with DM2.  相似文献   
57.
58.

Background

Among the strategies to increase the number of lung transplants, ex vivo lung perfusion (EVLP) represents a novel technique to expand the donor pool.

Methods

Data from donors referred to our center were retrospectively analyzed to identify grafts that could potentially be potentially reconditioned by EVLP and for comparison with those obtained by clinical application of EVLP program in our center.

Results

Among 75 rejected lungs, 23 organs have been identified as potentially treatable with EVLP with a hypothetic increase of lung transplant activity of 53%. After the introduction of the EVLP program in our center, lung transplantation with reconditioned grafts was performed in 7 (23%) patients with a 30% increase in transplant procedures.

Conclusion

Although less than expected, EVLP increased the number of lungs suitable for transplantation.  相似文献   
59.

Introduction

Hepatic artery stenosis (HAS) is an important complication after liver transplantation. However, studies are not conclusive in terms of definition, incidence, best treatment, and timing of intervention. The aim of this study was to evaluate the incidence of SSHA that occurred in a single center over the past 12 years, pointing out diagnostic and therapeutic strategies.

Methods

The incidence of HAS was reviewed in 258 liver transplant recipients between January 1999 and December 2011. All patients underwent Doppler ultrasound (DUS) at fixed times. Multidetector computed tomographic angiography (MDCTA) was performed to confirm the DUS findings.

Results

HAS occurred in 23 cases (9.3%). In all cases diagnosis was performed by DUS resulting in a sensitivity of 100% and a specificity of 99.6%. Based on DUS and MDCTA data integration, in 10 cases we adopted the “wait and see” strategy, whereas 13 patients underwent interventional radiology techniques.

Conclusion

DUS monitoring is efficacious in the diagnosis of HAS after liver transplantation. Interventional radiology procedures are safe and efficacious.  相似文献   
60.
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