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   1446篇
  免费   68篇
  国内免费   7篇
耳鼻咽喉   4篇
儿科学   43篇
妇产科学   33篇
基础医学   140篇
口腔科学   42篇
临床医学   73篇
内科学   341篇
皮肤病学   53篇
神经病学   112篇
特种医学   81篇
外科学   294篇
综合类   3篇
预防医学   71篇
眼科学   16篇
药学   97篇
中国医学   1篇
肿瘤学   117篇
  2024年   3篇
  2023年   8篇
  2022年   21篇
  2021年   34篇
  2020年   20篇
  2019年   31篇
  2018年   25篇
  2017年   30篇
  2016年   33篇
  2015年   50篇
  2014年   57篇
  2013年   58篇
  2012年   113篇
  2011年   116篇
  2010年   64篇
  2009年   53篇
  2008年   104篇
  2007年   80篇
  2006年   105篇
  2005年   76篇
  2004年   82篇
  2003年   91篇
  2002年   79篇
  2001年   11篇
  2000年   14篇
  1999年   18篇
  1998年   28篇
  1997年   25篇
  1996年   10篇
  1995年   12篇
  1994年   7篇
  1993年   12篇
  1992年   9篇
  1991年   8篇
  1990年   6篇
  1989年   5篇
  1988年   4篇
  1987年   1篇
  1986年   1篇
  1985年   2篇
  1984年   3篇
  1983年   1篇
  1981年   1篇
  1980年   1篇
  1979年   2篇
  1978年   2篇
  1977年   3篇
  1975年   1篇
  1968年   1篇
排序方式: 共有1521条查询结果,搜索用时 15 毫秒
21.
22.

Objective

The purpose of this cross-sectional study was to evaluate the association between loss of attachment (LA) which is clinical index of periodontitis and bone mineral density (BMD) of the lumbar vertebrae and femur measured with dual energy X-ray absorptiometry (DXA) in Japanese community-dwelling postmenopausal women.

Subjects and methods

Subjects were 347 women aged 55–74. The oral cavity was divided into 6 areas according to the WHO's method for the determination of the clinical attachment level score (CALscore); the LA was measured at 6 sites using a WHO probe in 17, 16, 11, 26, 27, 37, 36, 31, 46, and 47, and the values were recorded in mm. Then, we assessed BMD of the lumbar vertebrae (L2–L4) and femur (femoral neck, proximal part) by DXA. Based on these data, analysis of covariance was used to estimate relation between periodontitis and systemic BMD status excluding effect of age. Multiple linear regression analysis was used to estimate relation between periodontitis and BMD adjusted for 17 variables.

Results

Significant differences were observed in the mean value between the mean CALscore = 0 and CALscore ≥ 1 groups in the Z value in lumbar vertebrate (106.9 ± 18.7 vs. 102.3 ± 1.0, p < 0.05, t-test). Multiple regression analysis was conducted using the mean LA as dependent variable. Lumbar vertebral BMD (regression coefficient: B = −1.039 ± 0.379, p = 0.007), femoral neck BMD (B = −1.332 ± 0.627, p = 0.034), and proximal femoral BMD (B = −1.329 ± 0.536, p = 0.014) all exhibited a significant negative correlation with the mean LA.

Conclusion

A significant negative correlation was observed between periodontal disease and truncal bone BMD in this study.  相似文献   
23.
24.
25.
Day-service, commuting service for elderly people requiring care at home, is one healthcare option in Japan. To date, however, there exist no studies that have examined the effects of day-service use on health outcomes in Japan. The objective of the present longitudinal study was to determine whether there is an association between day-service use and various physical and mental health outcomes in elderly people requiring care. The subjects were 61 elderly persons who required between 25 and 49 min of assistance per day and used long-term care insurance. Measurements included demographic characteristics, activities of daily living, frequency of day-service use, body weight, height, grip strength, thigh muscle volume, degree of depression (Geriatric Depression Scale), the mini-mental state examination, and serum albumin and blood hemoglobin levels in the baseline and follow-up surveys two years later. In the day-service user group, the mean changes in serum albumin concentrations using day-service once, twice and three < or = times/week were -0.2, -0.3, and 0 g/dl, respectively, and the mean changes in blood hemoglobin were -0.7, -0.5, and 0.2 g/dl, respectively. The two-year change in serum albumin concentrations was less (p = 0.024) in subjects using day-service "three < or = times" (0 g/dl) than "twice" (-0.3 g/dl). The two-year change in blood hemoglobin was also less (p = 0.043) in subjects using day-service "three < or = times" (0.2 g/dl) than "twice" (-0.5 g/dl). The present study has shown that frequent use of day-service is useful in maintaining general nutritional status in elderly people.  相似文献   
26.
We report the first case of a teenage patient with chromosome 22q11.2 deletion syndrome who died of overwhelming postsplenectomy infection (OPSI) by Streptococcus pneumoniae despite appropriate prevention by pneumococcal vaccine. He had congenital heart disease and underwent several surgeries. Immunodeficiency had not been noticed clinically. Two years prior to death, splenectomy was performed for a drug-resistant idiopathic thrombocytopenic purpura and he was immunized with 23-valent pneumococcal polysaccharide vaccine (PPV23) 4 months after splenectomy. He died suddenly after a mild flu-like symptom. Autopsy was performed and OPSI was diagnosed. Blood culture was positive for S. pneumoniae. This isolated S. pneumoniae strain was serotypically un-typable by polyvalent serum agglutination test. On the contrary, multilocus sequence typing followed by DNA sequencing indicated the molecular serotype as 10A. Additional testing using monovalent and factor-specific sera confirmed the strain as serotype 10A. Ultrastructural observation of this S. pneumoniae strain showed that the polysaccharide capsule was thin and sparse. We speculate that the abnormal morphology of the capsule may have accounted for the polyvalent serum agglutination failure and may possibly be associated with severity of OPSI observed in this case. Chromosome 22q11.2 deletion syndrome is associated with certain immunodeficiency, especially susceptible to S. pneumoniae infections; however, fatal OPSI has not been reported. In addition to vaccination, prophylactic antibiotics may be necessary for these patients who are at risk of immunodeficiency.  相似文献   
27.
Information on obstructive sleep apnea-hypopnea syndrome (OSAHS) in Japan has been limited. The purposes of this clinical study were to evaluate the demographic characteristics of Japanese OSAHS patients and to assess how demographic factors are associated with OSAHS severity. We analyzed 3,659 OSAHS patients who underwent polysomnographic evaluation between January 2000 and December 2004 at 11 hospitals in Niigata Prefecture, Japan. Data consisted of apnea-hypopnea index (AHI) and demographic characteristics, including sex, age, and body-mass index, for statistical analysis. Levels of obesity were classified according to the WHO criteria. The male-to-female patient ratio for OSAHS was 4.6, and male patients presented more severe OSAHS than female patients. High AHI and a high proportion of moderate to serious OSAHS (AHI > or = 15) were found among the patients in their 30s, as well as female patients in their 70s and male patients in their 80s. The AHI and the proportion of moderate-to-serious OSAHS (AHI > or = 15) were greater in patients classified as underweight than in normal weight patients. In conclusion, there is a higher male predominance in the prevalence of OSAHS, and in both sexes, the results suggest different pathophysiological mechanisms of deteriorating OSAHS between adults under age 55 and adults 55 years or over. In addition, underweight patients exhibit more severe OSAHS than normal weight patients.  相似文献   
28.
Fluoride and abrasives in toothpastes may cause corrosion and deterioration of the titanium used for implants and other prostheses. The purpose of this study was to investigate how the presence or absence and types of fluoride and abrasives affected the titanium surface texture. Brushing with toothpastes was performed on pure-titanium discs using an abrasive testing machine. Unprocessed titanium discs without brushing were used as control samples. Surface roughness, color, and gloss of titanium were measured and the differences compared with the control were analyzed. Additionally, titanium surfaces and abrasives in toothpastes were observed using a scanning electron microscope to compare the surface texture of each sample. Some toothpastes (abrasive+) significantly increased the difference in surface roughness, color, and gloss, compared with ultrapure water. Toothpaste (fluoride+/abrasive+) that had many polygonal abrasive particles led to the largest color differences and exhibited notable scratches and a larger number of contaminant- or corrosion-like black spots. In contrast, brushing with toothpaste without fluoride or abrasives (fluoride−/abrasive−) caused little change to the titanium surface. These results suggest that both fluoride and abrasives in toothpaste used for brushing may be factors that affect surface texture and corrosion resistance of titanium.  相似文献   
29.
Previously we proposed a new analysis of natural killing activity, for comparison, employing an individual effector/ target cell ratio according to the peripheral number of effector cells. Using this analysis, we studied natural killing activities in chronic liver diseases and hepatocellular carcinoma (HCC). The activity in chronic persistent hepatitis remained nearly at the level of the nonactivated state, but that was significantly elevated in chronic active hepatitis. The activity in liver cirrhosis (LC) of Child's A or B grade was at the level of a nonactivated or reduced-activity state, while LC patients with impaired general conditions showed significantly elevated activities. In HCC, each of which was accompanied by LC in our cases, the activity appeared to be associated with the progression of HCC. Thus, natural killing activity showed a close relationship with the condition of chronic liver diseases.  相似文献   
30.
Background: It has been hypothesized that β‐3 adrenergic receptor and peroxisome proliferator‐activated receptor gamma (PPARγ) might have gene–environmental and gene–gene interactions in periodontal disease. The purpose of this study is to elucidate the interaction between β‐3 adrenergic receptor and PPARγ gene polymorphism with periodontal disease. Methods: Three hundred thirty‐two postmenopausal females were enrolled, and their serum high‐sensitivity C‐reactive protein (hsCRP) and hemoglobin A1c (HbA1c) were examined. β‐3 adrenergic receptor and PPARγ genotypes were then determined. An oral examination was performed. The number of remaining teeth was counted, and the probing depth (PD) and clinical attachment level (CAL) were measured. Prevalence‐rate ratios (PRRs) were calculated by multiple Poisson regression analyses to evaluate the relationship among periodontal disease markers, such as the number of sites with CAL 4 to 5 or ≥6 mm or PD 4 to 5 or ≥6 mm, and β‐3 adrenergic receptor polymorphisms, PPARγ polymorphisms, and the interaction term adjusted by age, hsCRP, and HbA1c, after converting the number of remaining teeth (n) to an offset variable. Results: In the participants with body mass index (BMI) ≥25, PRRs of β‐3 adrenergic receptor genotype (Trp/Arg and Arg/Arg) for periodontal disease markers were 0.13 to 0.70 (P <0.0001 to 0.74), those of PPARγ genotype (Pro/Pro) were 0.66 to 3.14 (P = 0.01 to 0.68), and those of the interaction term for the two genotypes were 1.69 to 12.61 (P <0.0001 to 0.33). However, in the participants with BMI <25, a constant tendency was not observed. Conclusion: The results confirmed a positive relationship between the interaction term for β‐3 adrenergic receptor genotype and PPARγ genotype and various periodontal markers in obese elderly females.  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