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   2115篇
  免费   173篇
  国内免费   4篇
耳鼻咽喉   14篇
儿科学   120篇
妇产科学   23篇
基础医学   268篇
口腔科学   63篇
临床医学   239篇
内科学   410篇
皮肤病学   64篇
神经病学   128篇
特种医学   128篇
外科学   348篇
综合类   40篇
一般理论   2篇
预防医学   137篇
眼科学   96篇
药学   94篇
中国医学   2篇
肿瘤学   116篇
  2021年   23篇
  2020年   17篇
  2019年   30篇
  2018年   42篇
  2017年   41篇
  2016年   31篇
  2015年   38篇
  2014年   43篇
  2013年   63篇
  2012年   97篇
  2011年   108篇
  2010年   82篇
  2009年   58篇
  2008年   95篇
  2007年   80篇
  2006年   97篇
  2005年   76篇
  2004年   57篇
  2003年   63篇
  2002年   61篇
  2001年   53篇
  2000年   50篇
  1999年   65篇
  1998年   33篇
  1997年   42篇
  1996年   43篇
  1995年   38篇
  1994年   28篇
  1993年   42篇
  1992年   45篇
  1991年   39篇
  1990年   44篇
  1989年   46篇
  1988年   42篇
  1987年   33篇
  1986年   31篇
  1985年   28篇
  1984年   26篇
  1983年   17篇
  1982年   21篇
  1981年   24篇
  1980年   22篇
  1979年   28篇
  1978年   30篇
  1977年   17篇
  1976年   23篇
  1975年   16篇
  1974年   23篇
  1969年   17篇
  1968年   19篇
排序方式: 共有2292条查询结果,搜索用时 15 毫秒
1.
Cidofovir is an acyclic nucleoside phosphonate with broad-spectrum activity against DNA viruses, including human papilloma virus (HPV). However, data on the efficacy of cidofovir in an immunosuppressive setting remain contradictory. We report for the first time on the promotion of the healing of recalcitrant warts in a patient with myelodysplastic syndrome with intravenous cidofovir treatment.  相似文献   
2.
3.
Motor vehicle rollover and static stability: an exposure study.   总被引:1,自引:0,他引:1       下载免费PDF全文
OBJECTIVES: This study examined vehicle rollovers in terms of site-specific exposure and speeds of vehicles of varying stability. METHODS: Fifty-one rollover sites in two states were visited at the same time of day and day of week as the rollover. A sample of vehicles moving in the same direction as the rollover were observed, and vehicle-specific data were obtained from identification numbers. RESULTS: Low stability, exacerbated by the addition of passengers, increased the risk of rollover. Speed was not correlated with stability and is not a confounder. CONCLUSIONS: Rollovers could be substantially reduced if motor vehicles were manufactured with a static stability of 1.2 or greater.  相似文献   
4.
5.
To understand the potential early responses of human bone and the calcium endocrine system to spaceflight, we studied 8 healthy men, aged 35-44 years before, during, and after bed rest in a -6 degrees head-down tilt model for microgravity. Based on a novel single-dose labeling schedule, average rates of bone formation in the iliac crest were reduced in 6, unchanged in 1, and increased in 1 following the bed rest period. The decrease was greatest for subjects whose daily walking miles were highest (r = -0.762, p less than 0.05, n = 7). Before a measurable increase in ionized serum calcium the sixth bed rest day, there was increased excretion of urinary calcium and sodium, evident the first 2 bed-rest days and parallel for the entire week (r = 0.92, p less than 0.001). Reduced excretion of phosphorus and 3', 5' cyclic adenosine monophosphate on the first and second bed rest days was followed by an increase in serum phosphorus by the sixth bed rest day. Depressed serum concentrations of parathyroid hormone and 1,25-dihydroxyvitamin D were manifest by the sixth and seventh bed rest days. The similarity of the response of bone and the calcium endocrine system of healthy men after only 7 days to results of longer term bed rest studies emphasizes the responsiveness of the adult human skeleton to biomechanical stimuli induced by changes in activity and/or position.  相似文献   
6.
Nasal septal deformity is a frequent clinical entity, and septoplasty comprises one of the most common procedures performed by otolaryngologists today. Its efficacy seems intuitive, however the literature reveals relatively few papers confirming its utility. In this study, all patients undergoing septal reconstruction (excluding septorhinoplasty) at three major teaching hospitals in Vancouver during the years 1988 to 1990 were reviewed retrospectively in a two-pronged study. Information was collected concerning symptoms, physical findings and surgical technique. In the second phase, patients were contacted by telephone in a blinded fashion. Data was collected concerning patient satisfaction regarding various parameters including initial and ultimate symptom resolution, acceptance of nasal packing and postoperative complications. The following conclusions may be drawn: 1) Septoplasty was successful in relieving nasal obstruction in 70.5% of patients. 2) Turbinate surgery including outfracturing appears to significantly improve the outcome of surgery. 3) Rhinitis, including allergy, congestion, postnasal drip and rhinorrhea did not significantly affect success in relieving nasal obstruction. 4) Nasal packing did not significantly affect the outcome, but was the most frequently complained of aspect of the surgery. Therefore, we do not feel nasal packing is necessary.  相似文献   
7.
All primary condylar total knee replacement arthroplasties (TKAs) performed from 1977 to 1984 at the authors' institution were divided into two groups based on the use of continuous passive motion (CPM) in the immediate postoperative period. The control group consisted of 73 patients who were treated with 95 TKAs without postoperative CPM. The average age was 65.4 years. The study group consisted of 38 patients who had 51 TKAs in which CPM was used postoperatively. The mean patient age was 62.8 years. The most common diagnoses in both groups were osteoarthritis and rheumatoid arthritis. Range of motion (ROM) was recorded preoperatively, at discharge, at three months, one year, two years, and at the last follow-up visit. There were no statistically significant differences in the ROM between the two groups at any of these time periods. At two years, the mean flexion and extension in the study group were 99 degrees and -4 degrees, respectively, compared to 103 degrees and -5 degrees in the control group. The average hospital stay was 11.2 days in the study group, whereas it was 15.1 days in control group. In the control group, there was one superficial infection, no deep infections, and four pulmonary emboli compared with three superficial infections, two deep infections, and no pulmonary emboli in the study group. There was no difference in the transfusion requirements between the two groups. CPM is advocated by the authors to help achieve discharge ROM earlier, but the protocol has been changed to begin CPM on the second postoperative day to allow the wound to stabilize.  相似文献   
8.
The receptor tyrosine kinase (RTK) Ret is activated by the formation of a complex consisting of ligands such as glial cell line-derived neurotrophic factor (GDNF) and glycerophosphatidylinositol-anchored coreceptors termed GFRalphas. During activation, Ret translocates into lipid rafts, which is critical for functional responses to GDNF. We found that Ret was rapidly ubiquitinated and degraded in sympathetic neurons when activated with GDNF, but, unlike other RTKs that are trafficked to lysosomes for degradation, Ret was degraded predominantly by the proteasome. After GDNF stimulation, the majority of ubiquitinated Ret was located outside of lipid rafts and Ret was lost predominantly from nonraft membrane domains. Consistent with the predominance of Ret degradation outside of rafts, disruption of lipid rafts in neurons did not alter either the GDNF-dependent ubiquitination or degradation of Ret. GDNF-mediated survival of sympathetic neurons was inhibited by lipid raft depletion, and this inhibitory effect of raft disruption on GDNF-mediated survival was reversed if Ret degradation was blocked via proteasome inhibition. Therefore, lipid rafts sequester Ret away from the degradation machinery located in nonraft membrane domains, such as Cbl family E3 ligases, thereby sustaining Ret signaling.  相似文献   
9.
10.
Background Cosmetic changes are to be expected after radiotherapy for skin tumours. Objectives This study aimed to answer the questions: How frequent are cosmetic changes after soft X‐ray therapy? Do treatment parameters, tumour thickness, localization and size of the irradiated field have a major influence? Were patients irritated by the visual appearance of the irradiated field? Methods In total, 2474 examinations of 1149 irradiated fields were performed. Results Hypopigmentation was found in 64.7% of examinations more than 90 days after therapy, teleangiectases in 43.1%, erythema in 24.8%, and hyperpigmentation in 16.8%. The frequency of hypopigmentation, teleangiectases and hyperpigmentation increased with time from X‐ray exposure; more than 4 years after therapy hypopigmentation was diagnosed in 91.8% and teleangiectases in 82.2% of examinations. Total dose, the time–dose–fractionation factor (TDF), field size and dose per fraction were significantly related to the frequency of cosmetic changes. Incidence rates of cosmetic changes differed by less than 15% if different treatment conditions were compared: thicker vs. thinner tumours, larger vs. smaller fields, higher vs. lower total doses, doses per fraction, and TDF. Frequencies of hypopigmentation, teleangiectases, erythema and hyperpigmentation differed by more than 15% between some localizations on the head. Women reported irritation by the visual appearance of the irradiated field in 12.6% of 1116 interviews, and men in 4.4% of 1284 interviews. Conclusions Cosmetic changes after soft X‐ray therapy are relatively frequent. Treatment parameters, tumour thickness and field size have only a minor influence. Few patients, but more women than men, were irritated by the visual appearance of the irradiated field.  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