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   647篇
  免费   29篇
  国内免费   3篇
耳鼻咽喉   3篇
儿科学   81篇
妇产科学   17篇
基础医学   96篇
口腔科学   32篇
临床医学   45篇
内科学   113篇
皮肤病学   10篇
神经病学   28篇
特种医学   7篇
外科学   72篇
综合类   9篇
预防医学   43篇
眼科学   33篇
药学   46篇
中国医学   5篇
肿瘤学   39篇
  2023年   8篇
  2022年   22篇
  2021年   27篇
  2020年   13篇
  2019年   22篇
  2018年   32篇
  2017年   16篇
  2016年   18篇
  2015年   13篇
  2014年   33篇
  2013年   45篇
  2012年   60篇
  2011年   49篇
  2010年   38篇
  2009年   25篇
  2008年   37篇
  2007年   27篇
  2006年   30篇
  2005年   34篇
  2004年   30篇
  2003年   38篇
  2002年   34篇
  2001年   2篇
  2000年   5篇
  1999年   3篇
  1998年   4篇
  1996年   3篇
  1995年   4篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1991年   1篇
  1988年   1篇
  1983年   1篇
  1970年   1篇
排序方式: 共有679条查询结果,搜索用时 15 毫秒
1.
OBJECTIVE: Surgical-site infection (SSI) is a serious and costly complication following coronary artery bypass graft (CABG). We analyzed surgical factors, microbiology, and complications at a 608-bed community teaching hospital to identify opportunities for prevention. METHODS: All patients undergoing CABG procedures from June 1997 through December 2000 were analyzed. Hospital records and postdischarge surveillance data were reviewed for demographics, surgical information, timing and classification of infection, microbiology, and bacteremic events. RESULTS: Of 3,443 patients undergoing CABG, sternal SSI developed in 122 (3.5%); 71 (58.2%) were classified as superficial SSI and 51 (41.8%) as deep SSI. Surgical antimicrobial prophylaxis was employed in all cases. On average, infection occurred 21.5 days (range, 4 to 315) after CABG. Most cases were diagnosed on readmission (59%); 20 cases (16%) were identified by postdischarge surveillance. Microbiological data were positive in 109 (89.3%), with a single pathogen implicated in most (86.2%). Gram-positive cocci were most frequently recovered (81%); gram-negative bacilli (17%), gram-positive bacilli (1%), and yeast (1%) were less common. Staphylococcus aureus was the most frequently isolated pathogen (49%). Bacteremia was noted in 22 instances (18%). It was significantly associated with deep SSI (P =. 002) and identified only in S. aureus cases. CONCLUSIONS: SSI complicated 3.5% of the procedures. S. aureus was implicated in most of the cases and was significantly associated with deep SSI. It was the only pathogen associated with secondary bacteremia. In addition to standard guidelines, targeted methods against S. aureus should help reduce the overall rate of SSI.  相似文献   
2.
Work-related repetitive motion disorders are costly. Immunohistochemical changes in bones resulting from repetitive reaching and grasping in 17 rats were examined. After 3-6 weeks, numbers of ED1+ macrophages and osteoclasts increased at periosteal surfaces of sites of muscle and interosseous membrane attachment and metaphyses of reach and nonreach forelimbs. These findings indicate pathological overloading leading to inflammation and subsequent bone resorption. INTRODUCTION: Sixty-five percent of all occupational illnesses in U.S. private industry are attributed to musculoskeletal disorders arising from the performance of repeated motion, yet the precise mechanisms of tissue pathophysiology have yet to be determined for work-related musculoskeletal disorders. This study investigates changes in upper extremity bone tissues resulting from performance of a voluntary highly repetitive, negligible force reaching and grasping task in rats. MATERIALS AND METHODS: Seventeen rats reached an average of 8.3 times/minute for 45-mg food pellets for 2 h/day, 3 days/week for up to 12 weeks. Seven rats served as normal or trained controls. Radius, ulna, humerus, and scapula were collected bilaterally as follows: radius and ulna at 0, 3, 4, 5, 6, and 12 weeks and humerus and scapula at 0, 4, and 6 weeks. Bones were examined for ED1-immunoreactive mononuclear cells and osteoclasts. Double-labeling immunohistochemistry was performed for ED1 (monocyte/macrophage lineage cell marker) and TRACP (osteoclast marker) to confirm that ED1+ multinucleated cells were osteoclasts. Differences in the number of ED1+ cells over time were analyzed by ANOVA. RESULTS: Between 3 and 6 weeks of task performance, the number of ED1+ mononuclear cells and osteoclasts increased significantly at the periosteal surfaces of the distal radius and ulna of the reach and nonreach limbs compared with control rats. These cells also increased at periosteal surfaces of humerus and scapula of both forelimbs by 4-6 weeks. These cellular increases were greatest at muscle attachments and metaphyseal regions, but they were also present at some interosseous membrane attachments. The number of ED1+ cells decreased to control levels in radius and ulna by 12 weeks. CONCLUSIONS: Increases in ED1+ mononuclear cells and osteoclasts indicate that highly repetitive, negligible force reaching causes pathological overloading of bone leading to inflammation and osteolysis of periosteal bone tissues.  相似文献   
3.
4.
Carcinoma of the oral cavity constitutes approximately 40% of overall malignant tumours in India, with an incidence of about 56,000 cases per year. Radiation responses in oral cancer cells by cytology have not been extensively studied. 102 patients with squamous cell carcinoma of the oral cavity treated by fractionated radiotherapy were studied. Serial scrape smears were taken from each tumour before and after irradiation. The abnormal nuclear counts per 1000 malignant cells were 1.6 and 14.1(p<0.001) for micronucleation, 0.9 and 5.5 (p<0.001) for nuclear budding, 7.6 and 28.1(p<0.001) for binucleation and 2.4 and 11.7(p<0.001) for multinucleation respectively. The study showed a significant rise in radiation induced cytological responses. In addition, radiation changes observed included abnormal and incomplete divisions of a nucleus, fibroblast like appearance cells, and enlargement of nuclear size as well as cytoplasmic granulation. These changes may have an important role to play in understanding the mechanism of cell killing after radiotherapy.  相似文献   
5.
India has the second highest number of cases of sickle cell disease (SCD) and affects the most socioeconomically disadvantaged communities living in a horizontal belt from Gujarat to Odisha state. Despite high prevalence, information about cerebral hemodynamics among children with SCD in India remains scarcely described.We performed transcranial Doppler (TCD) to assess cerebral hemodynamics among Indian children with SCD and evaluated their association with clinical and hematological parameters.Children aged 3-18years, diagnosed with SCD living in Raipur in Chhattisgarh and Ahmedabad in Gujarat state were recruited. TCD was performed to obtain flow velocities from middle cerebral (MCA), intracranial internal carotid (ICA) and basilar artery. Associations were evaluated between timed-average-mean-maximum velocities (TAMMV) and various clinical and hematological parameters.Our prospective study included 62 consecutive children with known SCD. Mean ± SD age of the study population was 9.8 ± 3.9 years and 31 (50%) were male. Mean ± SD hemoglobin was 8.64 ± 1.34 Gm/dL while the mean HbSS ± SD was 70.25 ± 15.27%. While 6 (9.6%) children had suffered from stroke during previous 2 years, 7 (11%) demonstrated abnormal TAMMV. Higher HbSS level along with history of iron chelation therapy, blood transfusion and/or stroke showed a trend towards having higher TAMMV.Stroke and cerebral hemodynamic alterations are common among Indian children with SCD. Larger studies with detailed neuroimaging and genetic evaluations are needed for better understanding, characterization, risk stratification as well as optimization of the timing of blood transfusion to reduce physical disabilities among Indian children with SCD.  相似文献   
6.
Objectives:To assess the null hypothesis that there is no difference in the rate of dental development and the occurrence of selected developmental anomalies related to shape, number, structure, and position of teeth between subjects with impacted mandibular canines and those with normally erupted canines.Materials and Methods:Pretreatment records of 42 subjects diagnosed with mandibular canines impaction (impaction group: IG) were compared with those of 84 subjects serving as a control reference sample (control group: CG). Independent t-tests were used to compare mean dental ages between the groups. Intergroup differences in distribution of subjects based on the rate of dental development and occurrence of selected dental anomalies were assessed using χ2 tests. Odds of late, normal, and early developers and various categories of developmental anomalies between the IG and the CG were evaluated in terms of odds ratios.Results:Mean dental age for the IG was lower than that for the CG in general. Specifically, this was true for girls (P < .05). Differences in the distribution of the subjects based on the rate of dental development and occurrence of positional anomalies also reached statistical significance (P < .05). The IG showed a higher frequency of late developers and positional anomalies compared with controls (odds ratios 3.00 and 2.82, respectively; P < .05).Conclusions:The null hypothesis was rejected. We identified close association of female subjects in the IG with retarded dental development compared with the female orthodontic patients. Increased frequency of positional developmental anomalies was also remarkable in the IG.  相似文献   
7.
8.
9.
10.

Objectives

Fractures of facial bones in children are relatively uncommon although both children and adults are subjected to similar types of injuries. This study aims to evaluate the epidemiology of facial bone fractures among children under 14 years, their management and outcome.

Materials and Methods

This retrospective study included maxillofacial injuries treated in 112 children under 14 years admitted due to maxillofacial injuries during the period from 2001 to 2011.

Results

Of them ten (8.93 %) were below 5 years, 44 (39.29 %) between 6 and 10 years and 58 (51.78 %) between 11 and 14 years of age. Male to female ratio was 1.8:1. Fall from a height was the most common etiology. The most common jaw involved in the fracture was the mandible. Conservative management was done in 83.04 % of cases and open reduction and internal fixation was performed in 16.96 % of cases. Five (4.46 %) cases accounted for post-operative wound infection.

Conclusion

Fracture of the mandible is the most common maxillofacial injury in children, most often caused by fall from a height. The osteogenic potential of the mandible in children leads to conservative management of these fractures. Opportunities for prevention of maxillofacial trauma should be taken into consideration by parents and care takers.  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