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   22394篇
  免费   1129篇
  国内免费   205篇
耳鼻咽喉   585篇
儿科学   1342篇
妇产科学   597篇
基础医学   1961篇
口腔科学   1097篇
临床医学   1688篇
内科学   4220篇
皮肤病学   581篇
神经病学   1350篇
特种医学   1111篇
外国民族医学   2篇
外科学   4481篇
综合类   542篇
现状与发展   1篇
一般理论   7篇
预防医学   934篇
眼科学   660篇
药学   1320篇
  4篇
中国医学   235篇
肿瘤学   1010篇
  2024年   21篇
  2023年   234篇
  2022年   338篇
  2021年   621篇
  2020年   413篇
  2019年   493篇
  2018年   699篇
  2017年   635篇
  2016年   769篇
  2015年   746篇
  2014年   1002篇
  2013年   1244篇
  2012年   1526篇
  2011年   1556篇
  2010年   905篇
  2009年   605篇
  2008年   1238篇
  2007年   1293篇
  2006年   1283篇
  2005年   1248篇
  2004年   1319篇
  2003年   1292篇
  2002年   1136篇
  2001年   745篇
  2000年   721篇
  1999年   467篇
  1998年   180篇
  1997年   140篇
  1996年   119篇
  1995年   65篇
  1994年   64篇
  1993年   50篇
  1992年   60篇
  1991年   60篇
  1990年   36篇
  1989年   51篇
  1988年   41篇
  1987年   30篇
  1986年   37篇
  1985年   23篇
  1984年   23篇
  1983年   13篇
  1982年   15篇
  1981年   12篇
  1980年   12篇
  1979年   20篇
  1978年   11篇
  1974年   12篇
  1973年   11篇
  1972年   12篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.

Purpose

To assess the role of E-cadherin as prognostic biomarker in upper tract urothelial carcinoma (UTUC) in a large multi-institutional cohort of patients.

Methods

Immunohistochemistry technique was used to evaluate E-cadherin expression in 678 patients with unilateral, sporadic UTUC treated with RNU. E-cadherin expression was considered decreased if 10 % or more cells had decreased expression (<90 %).

Results

Decreased E-cadherin expression was observed in 353 patients (52.1 %) and was associated with advanced pathological stage (P < 0.001), higher grade (P < 0.001), lymph node metastasis (P = 0.006), lymphovascular invasion (P < 0.001), concomitant carcinoma in situ (P < 0.001), multifocality (P = 0.004), tumor necrosis (P = 0.020) and sessile architecture (P < 0.001). Within a median follow-up of 30 months (interquartile range 15–57), 171 patients (25.4 %) experienced disease recurrence and 150 (21.9 %) died from UTUC. In univariable analyses, decreased E-cadherin expression was significantly associated with worse recurrence-free survival (P < 0.001) and cancer-specific survival CSS (P = 0.006); however, in multivariable analyses, it was not (P = 0.74 and 0.84, respectively). The lack of independent prognostic value of E-cadherin remained true in all subgroup analyses.

Conclusion

In UTUC patients treated with RNU, decreased E-cadherin expression is associated with features of biologically and clinically aggressive disease and worse outcome in univariable, but not multivariable, analyses. If E-cadherin’s association with factors of advanced disease is confirmed on UTUC biopsy specimens, it could be used to help in the clinical decision-making regarding kidney-sparing approaches and/or neo-adjuvant chemotherapy.
  相似文献   
992.
Toll-like receptors (TLRs) belonging to pattern recognition receptors are involved in maintaining testicular and epididymal immune homeostasis. The purpose of the current study was to investigate TLR4 expression in rat testis and epididymis throughout postnatal development. Weak staining was detected in peritubular myoid cells and immature Sertoli cells while no staining was observed in gonocytes during prepubertal period. However, TLR4 expression began to appear in spermatocytes in pubertal period and gradually increased in spermatids. An intense staining was observed in steps 5–19 spermatids in post pubertal and mature periods. Similarly, TLR4 expression in the testes steadily increased from pubertal period to mature period. Puberty also caused a significant increase in TLR4 expression in epididymis. TLR4 expression in cauda epididymis was lower as compared to those of other epididymal segments. The majority of epididymal epithelial cells exhibited apical TLR4 expression, whereas basal cells showed intense intracytoplasmic immunoreaction. We detected an intense staining in epididymal smooth muscle cells. The expression levels of TLR4 showed dynamic changes in both spermatogenic cells, and entire testicular and epididymal tissues during postnatal development. These results suggest that TLR4 expression contributes not only to inflammation but also to the development of spermatogenic cells.  相似文献   
993.
Acquired deficiency of anticoagulant proteins, due to loss in the urine, has been proposed as one of the major thrombogenic alterations in nephrotic syndrome (NS). Protein Z (PZ) is a single-chain vitamin K-dependent glycoprotein. Low PZ levels are reported to be a risk factor for thrombosis. The aim of this study was to investigate protein Z and other natural anticoagulant levels in children with NS. Thirty children aged between 1.5 and 12 years with NS (Groups I and II) and 19 age-and-sex-matched healthy controls (Group III) were enrolled into the study. Patients were divided into two groups: Group I (proteinuria >40 mg/m2/hr) and Group II (patients in remission). Plasma PZ levels in Group I were significantly lower than Group II (p=0.009) and group III (p=0.018). Plasma levels of AT III for Group I were significantly lower than for Groups II and III (p=0.009, p=0.005, respectively). Protein C levels in Group I were higher than in Group II and Group III (p=0.002, p=0.000, respectively). Protein Z levels positively correlated with serum total protein and albumin levels (p=0.003, p=0.003, respectively) and negatively with the degree of proteinuria (p=0.000). Protein Z levels were positively correlated with AT III (r=0.037, p=0.04). Along with the other coagulation abnormalities, decreased protein Z may contribute to increased risk of thromboembolic complications in children with NS. The negative correlation between proteinuria and PZ level suggests the possibility of renal PZ loss. Further studies are needed to investigate the mechanism and role of decreased PZ in NS.  相似文献   
994.
Lipoma arborescens is a rare intraarticular lesion, mainly affecting the knee. A fourteen-year-old girl presented with a slow-growing painless mass in the right knee, of a six-year history. There were no limitations in the movements of the knee. Magnetic resonance imaging (MRI) revealed multiple lesions showing villous lipomatous proliferation of the synovium in the supra- and retropatellar regions and effusion in the knee joint. The mass was excised with arthrotomy and synovectomy and a histopathologic diagnosis of lipoma arborescens was made. Two years postoperatively, and when the right knee was completely asymptomatic, she developed a similar mass in the suprapatellar region of the left knee. An MRI scan showed a mass lesion in the supra- and retropatellar regions, effusion in the knee joint, and a synovial cyst in the popliteal fossa. Again, arthrotomy and synovectomy were performed and the histopathologic diagnosis was lipoma arborescens. This case differs from simultaneously involved knees in that lipoma arborescens in the contralateral knee developed two years after the initial operation.  相似文献   
995.

Background

Fat mass and obesity-associated protein (FTO) gene expression is known to correlate with obesity. Our aim was to investigate the FTO gene expression in paired omental and subcutaneous human adipose tissues from morbid and obese patients. To understand the role of CD68-positive macrophages in adipose tissues, the correlation with adiposity parameters such as adipocyte diameter and adipocyte radius was also measured. Drug and adiposity correlations were also analyzed.

Methods

Paired omental and subcutaneous adipose tissue were excised during elective surgery from morbidly obese (n?=?9) and obese (n?=?5) patients. FTO expressions were determined by quantitative PCR. Tissue sections were analyzed for their CD68 protein expressions by immunuhistochemistry.

Results

Omental and subcutaneous adipose tissue FTO gene expression levels were not found to differ significantly among morbidly obese and obese study groups. Serum aspartate aminotransferase e and alanine transaminase levels were found to be in negative correlation with subcutaneous fat tissue FTO expression rate. Antidiabetic drug use was found to be in correlation with adiposity. Both subcutaneous and omental fat cell diameters were found to have correlation with antidiabetic drug use. Omental fat cell diameter was found to enlarge together with omental CD68 protein expression. Subcutaneous macrophage number decreased while omental fat cell radius increased. Omental macrophage number was found in correlation with subcutaneous macrophage number.

Conclusions

Antidiabetic therapy was found to increase adiposity in omental and subcutaneous fat. Further research is needed with larger samples to explore the exact role of FTO in obesity.  相似文献   
996.
The functional recovery of a replanted body part is as important as its viability. We compared four instruments frequently used for the evaluation of hand function after digital replantation. The functional results of 17 patients at least one year after replantation of a total digital amputation between 2004 and 2007 were evaluated according to the Tamai, Ipsen, Chen and Disabilities of the Arm, Shoulder and Hand questionnaires. Scores of each patient for each test were calculated and intra-individual comparisons were made. Correlation was significant at the 0.05 level (two tailed) for all tests. A high correlation (>0.71) was found between the Ipsen, Tamai and DASH tests. The Chen test had a moderate correlation with the other tests. We determined that Ipsen, Tamai and DASH tests have similar effectiveness in assessing hand function after replantation.  相似文献   
997.

Introduction

Because of the shortage of organs available for transplantation, living related sequential transplantation with the use of liver and a kidney from the same donor has emerged as a reasonable therapeutic alternative. However, there is insufficient literature about the complications that living donors experience after simultaneous kidney and liver transplantations.

Methods

From December 2001 to October 2009, 5 living donors provided simultaneous donation of livers and kidneys and 1 living donor donated first her kidney and then her liver. Demographic data of the donors and information concerning the surgery and postoperative observation were collected prospectively.

Results

All of the donors were female. The median age was 27.5 (range, 19–36) years. Indications requiring the simultaneous transplantation of livers and kidneys were primary hyperoxaluria type 1 (PH1) in 5 potential recipients and cirrhosis due to chronic hepatitis B infection and idiopathic chronic renal insufficiency in 1 potential recipient. Four recipients underwent right hepatectomy (segments 5–8) and right nephrectomy; 1 recipient underwent left hepatectomy (segments 2–4) and right nephrectomy; and 1 recipient underwent left lobectomy (segments 2–3) and right nephrectomy. There were no complications except in 1 donor (postoperative ileus). No donor developed hypertension or microalbuminuria.

Conclusions

With the right indications, appropriate preoperative evaluation, meticulous surgical technique, proper postoperative care, and long-term close monitoring to minimize morbidity and mortality risks, liver and kidney donation from the same donor can be considered for simultaneous kidney and liver transplantation.  相似文献   
998.
ObjectiveThe aim of this prospective study was to evaluate pre- and post-treatment MRI and CT findings of osteoid osteoma (OO) patients treated with radiofrequency thermo-ablation (RFTA) and to compare these findings with visual analog scale (VAS) scores.MethodsSixteen patients (4 females and 12 males; mean age of 18.87 ± 8.75 years (range: 8–37)) with OO were examined with CT and MRI, at baseline and at an average of 3 months following the procedure. On pre- and post-procedural CT and MRIs, OO-related findings were recorded. Treatment success was evaluated with VAS scores.ResultsBaseline VAS scores were 8 or 9 and follow-up scores were 0 or 1, indicating no early recurrences.Nidus diameters decreased significantly after the procedure (p = 0.027, p = 0.002, and p = 0.002; and p = 0.001, p = 0.001, p = 0.001 for AP, ML and CC nidus diameters for CT and MRI, respectively).The mean nidus volume were significantly decreased after the procedure (p = 0.001, for CT and MRI).On post-procedural images, cortical thickening, the signal intensity and contrast enhancement of the nidus and the extent of periostitis were significantly decreased (p = 0.019, p = 0.001, p = 0.001 and p = 0.034, respectively). There was no significant change in nidus calcification, perinidal cortical and intramedullary sclerosis, periosteal reaction, bone deformity, bone marrow and soft tissue edema, joint effusion and synovitis after the procedure (p = 0.253, p = 0.062, p = 0.245, p = 1, p = 1, p = 0.429, p = 0.371, p = 0.625, p = 1).ConclusionAlthough the changes in imaging findings may be helpful in early follow-up of OO patients treated with RFTA, these changes alone cannot be used with accuracy in predicting treatment response.Level of EvidenceLevel IV, Therapeutic Study.  相似文献   
999.
Objective: Pseudotumor cerebri (PTC) is a clinical condition characterized by signs and symptoms of increased intracranial pressure, such as headache and papilledema. Our aim was to investigate the etiological and clinical features of pseudotumor cerebri (PTC) in children. Materials and method: We performed a comprehensive analysis of epidemiology, diagnostic work-up, therapy, and clinical follow-up in 42 consecutive patients. Results: Totally 42 patients diagnosed with PTC [27 (64.3%) females and 15 (35.7%) males] were included in the study. The average age of the symptoms onset was 10.79 ± 3.43 years (range from 12 months to 17 years). Obesity was found in eleven (26.2%) of them. Two of the patients had familial mediterranean fever, two of them had posttraumatic PTC. The following diseases were one patient, respectively; mycophenolate mofetil-induced PTC, hypervitaminosis A induced PTC, corticosteroid induced withdrawal due to nephritic syndrome, use of oral contraceptives, Guillain–Barre syndrome, urinary tract infection, varicella-zoster virus infection and dural venous sinus thrombosis associated with otitis media. The most common symptom was headache, recorded in 76.2% of the patients. All patients were treated medically. Three patients in our group also required a ventriculoperitoneal shunt. Conclusion: Pseudotumor cerebri is an avoidable cause of visual loss, both in adults and children. Pre-pubertal obese girls are more common. Medical therapy appeared to be successful in treating pediatric PTC in most patients. Nevertheless, despite adequate treatment, children can rarely experience loss of visual field and acuity; thus, prompt diagnosis and management are important.  相似文献   
1000.
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