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   3926篇
  免费   208篇
  国内免费   18篇
耳鼻咽喉   81篇
儿科学   69篇
妇产科学   85篇
基础医学   525篇
口腔科学   48篇
临床医学   237篇
内科学   1164篇
皮肤病学   88篇
神经病学   189篇
特种医学   112篇
外科学   755篇
综合类   11篇
预防医学   65篇
眼科学   52篇
药学   231篇
中国医学   6篇
肿瘤学   434篇
  2023年   21篇
  2022年   39篇
  2021年   82篇
  2020年   43篇
  2019年   49篇
  2018年   61篇
  2017年   57篇
  2016年   75篇
  2015年   78篇
  2014年   102篇
  2013年   110篇
  2012年   186篇
  2011年   229篇
  2010年   107篇
  2009年   106篇
  2008年   198篇
  2007年   189篇
  2006年   200篇
  2005年   195篇
  2004年   164篇
  2003年   176篇
  2002年   158篇
  2001年   136篇
  2000年   145篇
  1999年   132篇
  1998年   54篇
  1997年   48篇
  1996年   36篇
  1995年   37篇
  1994年   27篇
  1993年   30篇
  1992年   89篇
  1991年   94篇
  1990年   80篇
  1989年   82篇
  1988年   65篇
  1987年   52篇
  1986年   53篇
  1985年   51篇
  1984年   29篇
  1983年   43篇
  1982年   16篇
  1981年   19篇
  1980年   13篇
  1979年   20篇
  1975年   19篇
  1971年   14篇
  1970年   17篇
  1969年   22篇
  1968年   16篇
排序方式: 共有4152条查询结果,搜索用时 15 毫秒
41.
This longitudinal study aimed to identify risk factors for the incidence and progression of radiographic knee osteoarthritis (OA). We examined the inhabitants of Miyagawa village aged ≥65 years every two years between 1997 and 2007. Anteroposterior radiographs of both knees were graded for OA using the Kellgren-Lawrence (K/L) grading system. Knee OA was defined as grade ≥2. We recorded the incidence of knee OA among participants in whom both knees changed from K/L grades 0 or 1 to ≥2 over a four-year follow-up period. We also recorded the progression of knee OA using this threshold among patients in whom one or both knees changed from K/L grades 2 or 3 to any higher grade over the follow-up period. Baseline data obtained from standard questionnaires, physical findings and X-rays included age, gender, body mass index (BMI), osteoporosis, Heberden’s nodes, knee range of motion (ROM), knee pain and cigarette smoking. The rates of incidence and progression of knee OA among 360 participants (241 women, 119 men) who fulfilled the study criteria were 4.0 and 6.0% per year, respectively. Female gender (odds ratio [OR] 2.849, 95% confidence interval [CI] 1.170–6.944) and high BMI (OR 1.243, 95% CI 1.095–1.411) were significantly associated with the incidence of knee OA, and restricted knee ROM (OR 0.941, 95% CI 0.892–0.992) was significantly associated with knee OA progression. Patients with a low knee ROM relative to grade of radiographic knee OA require more careful follow-up than those with a higher ROM.  相似文献   
42.
目的:评价冠状动脉内多普勒超声测量冠脉血流速度的应用价值。材料和方法:利用冠状动脉内多普勒血流钢丝(FloWire) 测量21 例冠状动脉狭窄患者和12 例正常冠状动脉的血流速度。结果:左前降支冠脉狭窄远端的平均最大血流速度(APV) 、舒张期最大血流速度(DPV) 和舒张期与收缩期流速比值(DSVR) 均显著低于正常组测值。结论:应用冠脉内多普勒超声技术可评价正常和冠脉狭窄病变患者的冠脉血流速度,这为定量研究冠脉血流动力学提供了新方法。  相似文献   
43.
Acute lung injury is a frequent and serious complication in patients with acute aortic dissection (AAD). Elevated neutrophil elastase has been reported to be one of the major determinants occurring in AAD. On admission, we administered sivelestat sodium hydrate, a neutrophil elastase inhibitor, to 11 patients with AAD who were medically treated to prevent lung injury. We compared their clinical course with that of 12 patients of control group in which sivelestat was not used prophylacticaly. Although there were 5 patients (42%) who suffered from respiratory failure and needed mechanical ventilation in the control group, no one needed intubation in the sivelestat group. Our study suggested that sivelestat sodium hydrate could be effective in preventing intubation due to respiratory failure. Further prospective study is necessary to evaluate prophylactic administration of sivelestat sodium hydrate in AAD.  相似文献   
44.
BACKGROUND: We evaluated the importance and mechanism of graft and host accommodation in hamster-to-rat cardiac xenotransplantation models. METHODS: To evaluate graft accommodation, accommodated hamster grafts (Group 2) were transplanted to na?ve host rats treated with FK506, and compared with na?ve hamster grafts (Group 1). To evaluate host accommodation, three groups were evaluated: naive hamster hearts were transplanted to na?ve hosts treated with FK506 (Group 3: 0.5 mg/kg, Group 4: 1.0 mg/kg) and splenectomy, and compared with accommodating hosts (Group 5) with FK506 0.5 mg/kg and splenectomy. We examined graft survival, histopathology, antihamster antibodies and B-1 cells in blood. RESULTS: Graft survival in Group 2 (3.4+/-0.9 days) was not significantly different from that in Group 1 (2.8+/-0.4 days). Graft survival in Groups 4 and 5 (>30 days) was significantly prolonged compared with that in Group 3 (6.0+/-0.7 days). Histopathology of Groups 1-3 showed humoral rejection, whereas Groups 4 and 5 showed normal histology and expression of protective genes. In Groups 1-3, antihamster immunoglobulin (Ig) M and B-1 cells increased significantly compared to Groups 4 and 5, where IgM and B-1 cells remained low or were reduced. CONCLUSIONS: Host accommodation was more important than graft accommodation. Accommodating grafts expressing protective genes were rejected with an elevation of both IgM and B-1 cells. In accommodated hosts, both IgM and B-1 cells decreased, suggesting that B-1 cells may be responsible for the production of antihamster antibodies. These results suggest that sufficient suppression of B-1 cells, resulting in decreased titers of antihamster antibodies, may play an important role in host accommodation.  相似文献   
45.
Symptoms of thoracolumbar junction disc herniation.   总被引:9,自引:0,他引:9  
Y Tokuhashi  H Matsuzaki  Y Uematsu  H Oda 《Spine》2001,26(22):E512-E518
STUDY DESIGN: A retrospective clinical review of patients with thoracolumbar junction disc herniation. OBJECTIVES: To evaluate the clinical features of thoracolumbar junction disc herniation and to prepare a chart for the level diagnosis in the neurologic findings and symptoms. SUMMARY OF BACKGROUND DATA: Thoracolumbar junction disc herniations show a variety of signs and symptoms because of the complexity of the upper and lower neurons of the spinal cord, cauda equina, and nerve roots. Furthermore, much is still unknown about thoracolumbar junction disc herniations because of their rare frequency. METHODS: The clinical features of 26 patients who had undergone operations for single disc herniations at T10-T11 through L2-L3 were investigated. Affected levels were as follows: 2 patients with disc herniation at T10-T11 disc, 4 patients at T11-T12, 3 patients at T12-L1, 6 patients at L1-L2, and 11 patients at L2-L3. The level of disc space of interest was confirmed with whole-spine plain roentgenograms. The caudal end of the cord was judged by magnetic resonance imaging and computed tomographic myelogram. RESULTS: Two patients with T10-T11 disc herniation showed moderate lower extremity weakness, increased patellar tendon reflex, and sensory disturbance of the entire lower extremities. Three of four patients with T11-T12 disc herniation experienced lower extremity weakness, and three patients had accentuated patellar tendon reflex. Sensory disturbance was observed in the anterolateral aspect of the thigh in one patient and on the entire leg in three patients. Bowel and bladder dysfunction was noted in three patients. In the T12-L1 disc herniation group (n = 3), muscle weakness and atrophy below the leg were advanced, and bowel and bladder dysfunction were also noted. Two of these three patients had bilateral drop foot, and one patient had unilateral drop foot; sensory disturbance was noted in the sole or foot and around the circumference of the anus, and the patellar tendon reflex and Achilles tendon reflex were absent. All six patients with L1-L2 disc herniation showed severe thigh pain and sensory disturbance at the anterior aspect or lateral aspect of the thigh. On the other hand, there were no clear signs of lower extremity weakness, muscle atrophy, deep tendon reflex, or bowel and bladder dysfunction in these patients. In the L2-L3 disc herniation group (n = 11), all patients had severe thigh pain and sensory disturbance of the anterior aspect or the lateral aspect of the thigh. Weakness in the quadriceps was noted in five patients and weakness in the tibialis anterior in two patients. Decreased or absence of patellar tendon reflex was observed in nine patients. Five patients had positive straight leg raising test results, and eight patients showed positive femoral nerve stretch test results. CONCLUSION: Among thoracolumbar junction disc herniations, T10-T11 and T11-T12 disc herniations were considered upper neuron disorders, T12-L1 disc herniations were considered lower neuron disorders, L1-L2 disc herniations were considered mild disorders of the cauda equina and radiculopathy, and L2-L3 disc herniations were considered radiculopathy. These findings had relatively distinct differences among herniated disc levels.  相似文献   
46.

Background

The primary abnormal manifestation in immunoglobulin A nephropathy (IgAN) is recurring bouts of hematuria with or without proteinuria. Although immunohistochemical analysis of renal biopsy tissue remains the gold standard not only for diagnosis but also for evaluating the activity of IgAN, new sensitive and reasonably specific noninvasive tests are emerging to guide therapeutic strategy applicable to all stages of IgAN. The present study examined serum levels of galactose-deficient IgA1 (Gd-IgA1) and its immune complex (IgA/IgG-IC) as noninvasive markers for the disease activity.

Methods

We enrolled 50 IgAN patients (male 40 %, median age 37 years) showing complete or partial clinical remission after steroid pulse therapy with tonsillectomy (TSP) whose clinical data and serum could be followed up for 3–5 years.

Results

Cross-sectional analysis revealed that the degree of hematuria and proteinuria were significantly associated with levels of Gd-IgA1 and levels of IgA/IgG-IC. Longitudinal analysis further showed that from the group of 44 patients with heavy hematuria before TSP, 31 patients showed complete disappearance of hematuria (group A), but the remaining patients did not (group B). Although the levels of Gd-IgA1 and IgA/IgG-IC in the two groups before TSP were similar, percentage decrease of Gd-IgA1 and IgA/IgG-IC levels in group A was significantly higher than in group B.

Conclusion

Disease activity of IgAN assessed by hematuria and proteinuria correlated with serum levels and changes of Gd-IgA1 and IgA/IgG-IC. These new noninvasive disease activity markers can be useful for future activity scoring system and guiding therapeutic approaches.  相似文献   
47.
In this study, we examined the effects of overexpression of SIRT1 on IL‐1β‐induced gene expression changes in human chondrocytes to explore a protective role of SIRT1 in human chondrocytes. SIRT1 was overexpressed in human chondrocytes by expression plasmid under stimulation with IL‐1β. SIRT1 was also inhibited by siRNA under stimulation with IL‐1β. Gene expression changes were examined by real‐time PCR. The interaction of SIRT1 and p65 (NF‐κB) were examined by Western blotting. SIRT1, MMP‐13, and ADAMTS‐5 expressions in human cartilage were examined by immunohistochemistry. IL‐1β stimulation significantly up‐regulated MMP‐1, 2, 9, and 13 and ADAMTS‐5. Overexpression of SIRT1 significantly inhibited the up‐regulation of those genes caused by IL‐1β while the inhibition of SIRT1 further increased them. In addition, the overexpression of SIRT1 markedly reduced the IL‐1β‐induced acetylation of p65. SIRT1 expression was clearly detected in the non‐OA cartilage while MMP‐13 and ADAMTS‐5 were undetectable. In contrast, in the OA cartilage, SIRT1 expression was decreased while MMP‐13 and ADAMTS‐5 were increased. Our observations suggested that SIRT1 can play a protective role by suppressing IL‐1β‐induced expressions of cartilage‐degrading enzymes partially through the modulation of the NF‐κB pathway. SIRT1 overexpression might be a new therapeutic approach for OA. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 531–537, 2013  相似文献   
48.
Postoperative superior mesenteric artery syndrome is a rare complication of left nephrectomy. We treated a case of superior mesenteric artery syndrome that occurred 7 days after radical left nephrectomy for renal cell carcinoma. The patient was a 54-year-old Japanese man who presented with gross hematuria. Abdominal computed tomography showed a 3.8 x 3.8 x 5 cm heterogeneous cystic mass in the left kidney. Transperitoneal left radical nephrectomy was performed because renal cell carcinoma was suspected. The patient resumed oral intake 3 days after surgery, but he began vomiting repeatedly from the 7th day after surgery. Gastroduodenography showed an abrupt vertical linear obstruction of the third portion of the duodenum. Superior mesenteric artery syndrome was diagnosed. Conservative therapy (indwelling nasogastric tube, intravenous hyperalimentation and postural changes) was effective.  相似文献   
49.
It is difficult to determine what kind of appropriate operations should be applied for which phase of chronic empyema would be administered, especially for a surgical management. We report that the postoperative outcomes of the treatment should be recommended for chronic empyema with the aid of omental flap transposition. Seven cases of chronic empyema (the averaged age was 66.1 +/- 7.5, 6 males and 1 female) in our hospital were operated during from June 1993 to January 2001. The disease-carrying time was 3 to 16 months and the inflammation findings at the admission were positive in all cases. The cause of chronic empyema was pneumonia (n = 3), plombage for tuberculosis (n = 2), and postlobectomy empyema (n = 2). As the first-stage of treatment for empyema cavity, intrathoracic tube drainage and lavage were performed for all cases. The operative procedures were described as below; one-stage operation with both thoracostomy and omental flap transposition was performed after the first-stage treatment (n = 2), simple thoracostomy (n = 1), and two-stage operation with thoracotomy and omental flap transposition (n = 4). Three of the 4 cases with two-stage operation could be completely treated for 1 month interval. However, the rest one case had not been able to be radically cured, which empyema had been extensively turned for the worse for one month after the two-stage operation. Thoracostomy had been redone, and it took 8 months to be cured. All cases could be finally recovered and discharged. On the priority of treatment for chronic empyema, at first, both thoracic tube drainage and thoracostomy should be performed as a first-stage operation, and if they could not be effective, after the combined inflammation was settled down, then the omental flap transposition should be considered as a two-stage operation.  相似文献   
50.
OBJECTIVE: The objective of this study was to determine whether the quality of life (QOL) in patients who underwent orthotopic bladder replacement after radical cystectomy was affected by the intestinal segment used for the creation of a neobladder. MATERIALS AND METHODS: A total of 52 patients who underwent radical cystectomy for bladder cancer were included in this study; i.e., 24 patients with an ileal neobladder and 28 patients with a sigmoid neobladder. QOL was evaluated using the SF-36 health-related QOL survey and a questionnaire designed to evaluate the continent status. RESULTS: The mean follow-up periods for patients with an ileal and a sigmoid neobladder was 40.2 and 43.1 months, respectively. The SF-36 survey revealed that patients with colon neobladder had a significantly higher score for role-emotional functioning than those with ileal neobladder, while there was no significant difference in the remaining seven scores between patients with ileal and colon neobladders; however, general health and social functioning in patients with both types of neobladder appeared to be significantly lower than those in the general population in the United States. The results of the questionnaire analyzing the continent status were also similar between these two groups, including the desire to urinate, the incidence of both day- and nighttime urinary leakage, the frequency of pad exchange, and the concern of urine odor. CONCLUSIONS: Six of the eight scales concerning health-related QOL were favorable with both patients with ileal and colon neobladders, and the health-related QOL in orthotopic neobladder patients except for role-emotional functioning was not affected by the segment of the intestine used for neobladder construction. Moreover, no significant differences were observed in the QOL associated with continent status between these two groups. Therefore, patients with both types of orthotopic neobladder were generally satisfied with their health-related as well as disease-specific QOL.  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