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   6415篇
  免费   351篇
  国内免费   8篇
耳鼻咽喉   38篇
儿科学   130篇
妇产科学   35篇
基础医学   848篇
口腔科学   185篇
临床医学   535篇
内科学   1042篇
皮肤病学   158篇
神经病学   542篇
特种医学   267篇
外科学   856篇
综合类   21篇
预防医学   1226篇
眼科学   145篇
药学   388篇
中国医学   4篇
肿瘤学   354篇
  2022年   51篇
  2021年   103篇
  2020年   49篇
  2019年   63篇
  2018年   90篇
  2017年   87篇
  2016年   107篇
  2015年   126篇
  2014年   148篇
  2013年   201篇
  2012年   349篇
  2011年   365篇
  2010年   212篇
  2009年   237篇
  2008年   328篇
  2007年   347篇
  2006年   297篇
  2005年   289篇
  2004年   302篇
  2003年   290篇
  2002年   232篇
  2001年   111篇
  2000年   134篇
  1999年   102篇
  1998年   59篇
  1997年   64篇
  1996年   107篇
  1995年   222篇
  1994年   214篇
  1993年   183篇
  1992年   210篇
  1991年   191篇
  1990年   130篇
  1989年   56篇
  1988年   48篇
  1987年   64篇
  1986年   60篇
  1985年   45篇
  1984年   36篇
  1983年   32篇
  1982年   21篇
  1981年   24篇
  1980年   24篇
  1979年   30篇
  1978年   27篇
  1977年   26篇
  1975年   25篇
  1974年   20篇
  1973年   25篇
  1971年   18篇
排序方式: 共有6774条查询结果,搜索用时 15 毫秒
81.
BackgroundAddition of vitamin E to polyethylene is theorized to reduce the potential for oxidative wear in acetabular components. This paper presents a multicenter prospective cohort study that reports on outcomes from use of a Vitamin E–infused highly cross-linked polyethylene acetabular cup.MethodsPatients were recruited across nine medical institutions. Clinical outcome measures recorded were the Harris Hip Score, visual analogue score for pain and satisfaction. Evidence of implant loosening or osteolysis was collected radiologically. Cup survival and reasons for revision in relevant cases were also recorded. Data collection was undertaken preoperatively, at 6-12 weeks, 6 months, 1 year, 2 years, and 5 years. A total of 675 patients were recruited, with 450 cases available at final review. Data regarding cup survival was available to 8 years and 9 months postoperatively.ResultsImprovements in both the Harris Hip Score and visual analogue score for pain and satisfaction were recorded at all time points, with these being maintained through the length of follow-up. In total, 89% of cups were implanted within the Lewinnek safe zone. A lucent line was identified in one case, with no evidence of acetabular osteolysis observed throughout the follow-up period. Cup survival was 98.9% at 8 years and 9 months. No revisions for aseptic loosening were observed.ConclusionsThe use of a vitamin E–infused polyethylene acetabular cup demonstrates reassuring patient-reported outcomes, radiological measures, and cup survival at medium to long-term follow-up.  相似文献   
82.
The number of patients returning to dialysis after graft failure increases. Surprisingly, little is known about the clinical and immunological outcomes of this cohort. We retrospectively analyzed 254 patients after kidney allograft loss between 1997 and 2017 and report clinical outcomes such as mortality, relisting, retransplantations, transplant nephrectomies, and immunization status. Of the 254 patients, 49% had died 5 years after graft loss, while 27% were relisted, 14% were on dialysis and not relisted, and only 11% were retransplanted 5 years after graft loss. In the complete observational period, 111/254 (43.7%) patients were relisted. Of these, 72.1% of patients were under 55 years of age at time of graft loss and only 13.5% of patients were ≥65 years. Age at graft loss was associated with relisting in a logistic regression analysis. In the complete observational period, 42 patients (16.5%) were retransplanted. Only 4 of those (9.5%) were ≥65 years at time of graft loss. Nephrectomy had no impact on survival, relisting, or development of dnDSA. Patients after allograft loss have a high overall mortality. Immunization contributes to long waiting times. Only a very limited number of patients are retransplanted especially when ≥65 years at time of graft loss.  相似文献   
83.
 As it is suggested that the androgen receptor mechanism is required for prostatic development, we attempted to determine the appearance, expression and distribution of the androgen receptor in embryonic, infantile and pubertal human prostate. Using mono- and polyclonal antibodies and a digoxigenin-labeled 713 bp riboprobe, the androgen receptor expression in paraffin sections of fetal, infantile, and pubertal prostates was studied at the protein and RNA level. Under highly standardized conditions, application of the polyclonal antibodies resulted in a weak cytoplasmic and nuclear labeling of the epithelium of fetal glands. No immunoreaction was obtained with monoclonal antibodies. Applying the polyclonal antibody to pubertal and adult specimens, immunoreactivity of the androgen receptor was positive in nuclei of adluminal and basal epithelial cells, in interstitial and vascular smooth muscle cells and vascular endothelium, whereas ganglionic cells and enteroendocrine cells were negative. In situ hybridization with the digoxigenin-labeled riboprobe gave clear positive results already in epithelium of very young fetal specimens. A semiquantitative visual evaluation of in situ hybridizations showed that intermediate intensity of expression was increased in pubertal and adult specimens, whereas strong expression was reduced in prostatic epithelium. Conclusions: The essential findings are: (1) an early expression of androgen receptor mRNA in the fetal prostate; (2) no immunoreaction of monoclonal antibodies against the androgen receptor in the same specimens, (3) a decrease of androgen receptor mRNA expression, but increase in immunoreactivity of the androgen receptor protein with the onset of glandular maturation during puberty. Accepted: 29 September 1997  相似文献   
84.
A wide spectrum of protocols is available for rehabilitation after anterior cruciate ligament reconstruction, and little agreement exists on the specifics of strengthening exercises or the sequence of activities. In this article, we discuss the current rehabilitative techniques used at the Mayo Clinic for athletes who have undergone anterior cruciate ligament reconstruction. These techniques are based on established principles of rehabilitation, clinical experience, and new information about the related biomechanics of the knee. An illustrative case reflects the benefits of this rehabilitation program, which lasts up to 1 year and is divided into five stages. The early stages focus on protected mobilization and a strengthening program that emphasizes closed rather than open kinetic chain exercises. Later, neuromuscular-proprioceptive training and sport-specific agility training redevelop the reaction time and the "coordination engrams" necessary for athletic competition. High-quality surgical care and a closely supervised rehabilitation program, based on kinesiologic and biomechanical factors as they pertain to the anterior cruciate ligament, are necessary for a successful outcome.  相似文献   
85.
Known mutagens and carcinogens in the diet were compiled and the risk of cancer was estimated on the basis of average exposure levels in Switzerland and carcinogenic potencies from rodent bioassays. The analysis showed that, except for alcohol, the sum of all known dietary carcinogens could only explain a few percent of the cancer deaths attributed by epidemiologists to dietary factors. The discrepancy was explained by a “carcinogenicity” of excess macronutrients. This hypothesis was based on an evaluation of dietary restriction experiments in rats and mice, where a dramatic reducing effect on spontaneous tumour formation was seen. From these experiments, a "carcinogenic potency" was deduced for food in excess (TD50 approximately 16 g/kg per day). Overnutrition in Switzerland was converted into excess food intake and the cancer risk estimated on the basis of the TD50 value. The resulting risk of 60,000 cases per one million lives would allow to explain by overnutrition almost all "diet-related" cancer deaths in humans.  相似文献   
86.
87.
88.
89.
90.
Lutz S 《Modern healthcare》1993,23(30):49, 51-42, 54
  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