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   3464篇
  免费   484篇
  国内免费   4篇
耳鼻咽喉   9篇
儿科学   121篇
妇产科学   52篇
基础医学   214篇
口腔科学   74篇
临床医学   218篇
内科学   460篇
皮肤病学   18篇
神经病学   108篇
特种医学   202篇
外科学   252篇
综合类   23篇
一般理论   10篇
预防医学   1933篇
眼科学   57篇
药学   67篇
中国医学   1篇
肿瘤学   133篇
  2023年   34篇
  2022年   56篇
  2021年   40篇
  2020年   100篇
  2019年   34篇
  2018年   112篇
  2017年   106篇
  2016年   120篇
  2015年   105篇
  2014年   108篇
  2013年   185篇
  2012年   70篇
  2011年   80篇
  2010年   132篇
  2009年   145篇
  2008年   77篇
  2007年   91篇
  2006年   112篇
  2005年   81篇
  2004年   68篇
  2003年   68篇
  2002年   128篇
  2001年   114篇
  2000年   89篇
  1999年   163篇
  1998年   170篇
  1997年   210篇
  1996年   224篇
  1995年   139篇
  1994年   69篇
  1993年   127篇
  1992年   53篇
  1991年   33篇
  1990年   41篇
  1989年   48篇
  1988年   49篇
  1987年   37篇
  1986年   50篇
  1985年   42篇
  1984年   26篇
  1983年   31篇
  1982年   22篇
  1981年   21篇
  1980年   11篇
  1979年   16篇
  1978年   12篇
  1977年   15篇
  1976年   23篇
  1975年   13篇
  1974年   7篇
排序方式: 共有3952条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Objectives Compare the effect of high doses of inhaled corticosteroids on bone loss in subjects with moderate to severe asthma or mild asthma, and examine the influence of dietary intake on bone metabolism. Design A survey on the effects of corticotherapy and nutrition on bone density was conducted in 74 subjects currently being treated for asthma in the asthma clinic of Hospital Laval (Sainte-Foy, Quebec, Canada). Fifty-eight subjects completed the study (attrition RATE=15%).

Main outcome measures In all subjects expiratory volumes were determined and urinary analysis was conducted for hydroxyproline, calcium, phosphorus, and cortisol levels. Osteocalcin, calcium, phosphorus, cortisol, alkaline phosphatase, and γ-glutamyltransferase levels were measured in blood samples. Bone density of the lumbar spine was determined by means of dual-energy x-ray absorptiometry. Nutrition evaluation was based on a 3-day food diary analyzed using progiciel Nutri 91. The nutritional parameters examined were calcium; phosphorus; magnesium; zinc; vitamins A, C, and D; protein; total fiber; oxalates; energy; caffeine; and alcohol in relation to bone density.

Subjects Thirty-one patients with moderate to severe asthma who had been taking more than 1,000 μg beclomethasone per day or the equivalent for more than 2 years and 27 patients with mild asthma who were taking less than 500 μg beclomethasone per day or the equivalent.

Statistical analyses performed Four factor analysis of variance with hierarchized interactions of four levels, Duncan's test, Pearson correlation coefficients.

Results Blood levels of osteocalcin and protein intake were lower in patients with moderate to severe asthma than in those with mild asthma (P<.05). Significant correlations (P<.02) were observed between bone density and calcium intake (r=.40), phosphorus intake (r=.35), protein intake (r=.30), and serum alkaline phosphatase level (r=−.30). Bone density was not significantly different between the two groups of patients with asthma.

Applications A follow-up of patients with asthma who are taking inhaled corticosteroids is needed to assess bone density, osteocalcin levels, and dietary intakes of calcium. Verify if osteocalcin level decreases over time in patients with moderate to severe asthma, monitor possible modifications in bone density, and verify if the correlation between dietary calcium and bone density is maintained. J Am Diet Assoc. 1997;97:1401–1406.  相似文献   

5.
6.
Sonoelasticity imaging of prostate cancer: in vitro results   总被引:2,自引:0,他引:2  
  相似文献   
7.
8.
Reduced bone mineral density (BMD) was sporadically reported in patients with Marfan syndrome. This may or may not place the Marfan patient at increased risk for bone fracture. In comparing the BMDs of our patients with those reported in the literature, it seemed that agreement between values, and hence the degree of osteoporosis or osteopenia reported, was dependent on the instrumentation used. The objective of this study was to statistically assess this impression. Bone mineral density measurements from our previously published study of 30 adults with Marfan syndrome performed on a Lunar DPXL machine were compared with studies published between 1993–2000 measured using either Lunar or Hologic bone densitometry instruments. The differences of our measurements compared with those made on other Lunar machines were not statistically significant, but did differ significantly with published results from Hologic machines (P < 0.001). Before progress can be made in the assessment of BMD and fracture risk in Marfan patients and in the evidence-based orthopedic management of these patients, standardization of instrumental bone density determinations will be required along with considerations of height, obesity, age, and sex.  相似文献   
9.
10.
Reconstruction of musculoskeletal defects about the knee for tumor   总被引:6,自引:1,他引:5  
One of the most challenging problems of limb salvage is a large tumor involving the knee joint. Since 1970, 79 patients, ranging in age from 14 to 74 years (mean, 27 years), have had reconstruction of the knee after en bloc resection of a primary bone tumor. Sixty-one patients had lesions involving the distal femur, with a mean resection length of 13.5 cm, and 18 patients had lesions involving the proximal tibia, with a mean resection length of 10.5 cm. Thirty-nine patients had malignant lesions, of which osteosarcomas predominated, and 40 patients had benign tumors, of which giant cell tumors were the most prevalent. Reconstruction was done with a custom total knee arthroplasty in 41 patients, a resection arthrodesis in 27, and an allograft in 11. The functional results were graded according to the rating system devised by the Musculoskeletal Tumor Society. of the patients with resection arthroplasty, 70% had a good or excellent rating, although ten required revision. Of the patients with resection arthrodesis, 74% had a good or excellent rating, as did 55% of the patients with osteochondral allografts. When a limb salvage procedure is done, careful consideration must be given to the type of procedure chosen to reconstruct the knee. This decision is based on a number of factors related to the tumor and the patient. Although these various procedures promise functional restoration, the reconstructive procedure should be individualized and designed to meet the needs of the patient.  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