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   3298篇
  免费   151篇
  国内免费   7篇
耳鼻咽喉   39篇
儿科学   132篇
妇产科学   51篇
基础医学   421篇
口腔科学   38篇
临床医学   242篇
内科学   752篇
皮肤病学   72篇
神经病学   417篇
特种医学   186篇
外科学   489篇
综合类   10篇
一般理论   1篇
预防医学   213篇
眼科学   36篇
药学   198篇
中国医学   15篇
肿瘤学   144篇
  2023年   21篇
  2021年   43篇
  2020年   25篇
  2019年   52篇
  2018年   60篇
  2017年   43篇
  2016年   70篇
  2015年   85篇
  2014年   88篇
  2013年   126篇
  2012年   184篇
  2011年   166篇
  2010年   100篇
  2009年   96篇
  2008年   151篇
  2007年   175篇
  2006年   154篇
  2005年   144篇
  2004年   141篇
  2003年   132篇
  2002年   104篇
  2001年   112篇
  2000年   99篇
  1999年   91篇
  1998年   17篇
  1997年   23篇
  1996年   17篇
  1995年   17篇
  1992年   47篇
  1991年   52篇
  1990年   47篇
  1989年   44篇
  1988年   36篇
  1987年   50篇
  1986年   41篇
  1985年   51篇
  1984年   30篇
  1983年   32篇
  1982年   25篇
  1981年   35篇
  1979年   40篇
  1978年   27篇
  1976年   16篇
  1975年   19篇
  1974年   30篇
  1973年   32篇
  1972年   18篇
  1971年   26篇
  1970年   22篇
  1967年   19篇
排序方式: 共有3456条查询结果,搜索用时 31 毫秒
1.
2.
3.

Background

Nursing care insurance funds are supposed to deliver preventive services in nursing homes. The strengthening of cognitive resources is considered as one field of action.

Aim

The preventive effectiveness of physical activity on cognitive performance in nursing home residents shall be evaluated.

Methods

A systematic search was carried out in the databases MEDLINE, the Cochrane Library, EMBASE, CINAHL, PsycINFO and PEDro. Results were combined in random-effects meta-analyses.

Results

Taking into account 13 primary studies, it was shown that those participating in physical activity showed statistically significant greater cognitive performance compared to controls (SMD = 0.43, 95% CI 0.20–0.66, p = 00002). Subgroup analyses suggest that nursing home residents with different cognitive impairments might benefit from long-lasting physical activity interventions. Due to the high risk of bias in included studies, the results must be interpreted with caution.

Conclusion

Physical activity might be effective in the inpatient care setting. Further studies with longer intervention periods are required.
  相似文献   
4.
Purpose

Psychosomatic symptoms and mental health problems are highly prevalent in multimorbid elderly people challenging general practitioners to differentiate between normal stress and psychopathological conditions. The 4DSQ is a Dutch questionnaire developed to detect anxiety, depression, somatization, and distress in primary care. This study aims to analyze measurement equivalence between a German version and the original Dutch instrument.

Methods

A Dutch and a German sample of multimorbid elderly people, matched by gender and age, were analyzed. Equivalence of scale structures was assessed by confirmatory factor analysis (CFA). To evaluate measurement equivalence across languages, differential item functioning (DIF) was analyzed using Mantel–Haenszel method and hybrid ordinal logistic regression analysis. Differential test functioning (DTF) was assessed using Rasch analysis.

Results

A total of 185 German and 185 Dutch participants completed the questionnaire. The CFA confirmed one-factor models for all scales of both 4DSQ versions. Nine items in three scales were flagged with DIF. The anxiety scale showed to be free of DIF. DTF analysis revealed negligible scale impact of DIF.

Conclusions

The German 4DSQ demonstrated measurement equivalence to the original Dutch instrument. Hence, it can be considered a valid questionnaire for the screening for mental health problems in primary care.

  相似文献   
5.
6.
7.
Diabetes mellitus (DM) is associated with an increased risk of mild cognitive impairment, dementia and stroke. The association between DM and dementia appears to be stronger for vascular cognitive impairment than for Alzheimer’s disease, suggesting cerebrovascular disease may be an important factor in cognitive impairment in DM. Although the exact mechanisms by which DM affects the brain remain unclear, changes to brain vasculature, disturbances of cerebral insulin signaling, insulin resistance, glucose toxicity, oxidative stress, accumulation of advanced glycation end products, hypoglycemic episodes, and alterations in amyloid metabolism may all be involved. Cognitive impairment and dementia associated with DM may also be mediated via vascular risk factors, in particular brain ischemia, the occurrence of which can have an additive or synergistic effect with concomitant neurodegenerative processes. To date, no drug has been approved for the treatment of vascular dementia and there are no specific pharmacological treatments for preventing or reducing cognitive decline in patients with DM. Most focus has been on tighter management of vascular risk factors, although evidence of reduced cognitive decline through reducing blood pressure, lipid-lowering or tighter glycemic control is inconclusive. Tailored, multimodal therapies may be required to reduce the risk of cognitive dysfunction and decline in patients with DM. The use of pleiotropic drugs with multimodal mechanisms of action (e.g., cerebrolysin, Actovegin) may have a role in the treatment of cognitive dysfunction and their use may warrant further investigation in diabetic populations.  相似文献   
8.

Background

The primary aim of this study was to evaluate the prevalence of vitamin D deficiency and secondary hyperparathyroidism after Roux-en-Y gastric bypass. Secondly, we have tried to assess predictors for vitamin D deficiency.

Methods

Five hundred thirty-seven patients who underwent primary Roux-en-Y gastric bypass surgery between 1993 and 2003 at the Örebro University Hospital and Uppsala University Hospital were eligible for the study. Patients were asked to provide a blood sample between November 2009 and June 2010 and to complete a questionnaire about their postoperative health status. Serum values of 25-OH vitamin D, parathyroid hormone (PTH), alkaline phosphatase (ALP) and calcium were determined.

Results

Follow-up was completed in 293 patients, of which 83 % were female, with an age of 49?±?9.9 years after a median time of 11?±?2.8 years. Vitamin D, PTH and albumin-corrected calcium values were 42?±?20.4 nmol/L, 89.1?±?52.7 ng/L and 2.3?±?0.1 mmol/L, respectively. Of all patients, 65 % were vitamin D deficient, i.e. 25-OH vitamin D <50 nmol/L, and 69 % had PTH above the upper normal reference range, i.e. >73 ng/L. Vitamin D was inversely correlated with PTH levels (p?<?0.001) and positively correlated with calcium (p?=?0.016). Vitamin D did not correlate with ALP. The only factor found to predict vitamin D deficiency was high preoperative body mass index (BMI) (p?=?0.008), whereas gender, age, time after surgery and BMI at follow-up did not.

Conclusions

Vitamin D deficiency and secondary hyperparathyroidism after Roux-en-Y gastric bypass (RYGB) were confirmed in our study because 65 % of patients had vitamin D deficiency, and 69 % had increased PTH levels more than 10 years after surgery. These data are alarming and highlight the need for improved long-term follow-up. Vitamin D deficiency does not seem to progress with time after surgery, possibly due to weight loss. Only preoperative BMI, cutoff point 43 kg/m2, was a predictor of vitamin D deficiency at follow-up. Improved long-term follow-up of patients that undergo RYGB is needed.  相似文献   
9.
Magnetic resonance (MR) imaging has become an essential tool in the evaluation of neonatal encephalopathy. Magnetic resonance-compatible neonatal incubators allow sick neonates to be transported to the MR scanner, and neonatal head coils can improve signal-to-noise ratio, critical for advanced MR imaging techniques. Refinement of conventional imaging techniques include the use of PROPELLER techniques for motion correction. Magnetic resonance spectroscopic imaging and diffusion tensor imaging provide quantitative assessment of both brain development and brain injury in the newborn with respect to metabolite abnormalities and hypoxic-ischemic injury. Knowledge of normal developmental changes in MR spectroscopy metabolite concentration and diffusion tensor metrics is essential to interpret pathological cases. Perfusion MR and functional MR can provide additional physiological information. Both MR spectroscopy and diffusion tensor imaging can provide additional information in the differential of neonatal encephalopathy, including perinatal white matter injury, hypoxic-ischemic brain injury, metabolic disease, infection, and birth injury.  相似文献   
10.
The efficacy of autologous peripheral stem cells given as mobilized whole blood or leukapheresis product for hematopoietic rescue after intensive chemotherapy was studied in 34 consecutive female patients with high-risk breast cancer. All patients received six cycles of chemotherapy regimen EC (epirubicin 150 mg/m2 and cyclophosphamide 1250 mg/m2) at 14-day intervals. In the first cycle, chemotherapy was given on day 1, and 24 h later mobilization of PBPC was started with G-CSF at a dose of 5 microg/kg/day for 13 days. In all other cycles, G-CSF was given at the same dose from day 7. On days 11, 12, and 13, leukaphereses were performed, and whole blood was collected on day 14 (the peak incidence of colony-forming units-granulocyte-macrophage [CFU-GM] burst-forming units-erythrocyte [BFU-E], and colony-forming unit-granulocyte-erythrocyte-macrophage-megakaryocyte [CFU-GEMM]). The second cycle of chemotherapy was started on day 15, and 24 h later, whole blood (collected in the first cycle) was reinfused, and the same was done in the third cycle. In the fourth to sixth chemotherapy cycles, leukapheresis product was used for hematopoietic rescue. The median increment of absolute values in both whole blood and leukapheresis product was as follows: CD34+ cells over baseline was approximately 17.4-fold, CFU-GM was 85.3-fold, BFU-E was 95.9-fold, and CFU-GEMM was 44.2-fold. In the cycles with whole blood support, the mean values of applied progenitors per cycle were CD34+ cells 1.52 x 10(6)/kg, CFU-GM, 1.18 x 10(5)/kg, BFU-E 2.54 x 10(5)/kg, CFU-GEMM 0.31 x 10(5)/kg. In the courses with PBPC support, the mean values of progenitors were CD34+ 2.04 x 10(6)/kg, CFU-GM 1.59 x 10(5)/kg, BFU-E 2.87 x 10(5)/kg, and CFU-GEMM 0.34 x 10(5)/kg. Leukopenia in patients supported with whole blood versus leukapheresed PBPC was as follows: grade 4, 13/6 (38.2%/17.6%), grade 3, 19/23 (55.9%/70.6%), and grade 2, 1/4 (2.9%/11.8%), respectively. Thrombocytopenia was grade 4, 11/6 (32.4%/17.6%), grade 3, 10/7 (29.4%/20.6%), grade 2, 7/13 (20.6%/38.2%), and grade 1, 6/6 (17.6%/17.6%), respectively. The median follow-up analysis was at 24.6 (7-36) months. High-risk patients previously treated with surgery and adjuvant chemotherapy (n = 5) were not evaluated for response. In 21 patients with locally advanced or inflammatory breast carcinoma the response rate (RR) was 94%, CR was 90%, and PR was 15%. No response to therapy was observed in 1 patient. In 8 patients with metastatic disease, RR was 75%, there was no CR, and PR was 75%. Two patients died during therapy. Relapse-free survival (RFS) in the adjuvant group was 23.7 (range 12-36) months and in the group with locally advanced disease was 18.2 (range 7-27) months. In the group with metastatic disease, time to tumor progression (TTP) was 12.1 (range 1-16) months. Mean duration of hospital stay for whole blood reinfusion in the second and third chemotherapy cycles was 6.7 (range 5-8) days and for PBPC in the fourth to sixth cycles was 6.2 (range 4-8) days, which at p < 0.001 was not statistically significant.  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