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   7504篇
  免费   354篇
  国内免费   49篇
耳鼻咽喉   43篇
儿科学   125篇
妇产科学   50篇
基础医学   874篇
口腔科学   158篇
临床医学   436篇
内科学   2211篇
皮肤病学   77篇
神经病学   606篇
特种医学   432篇
外科学   1452篇
综合类   24篇
预防医学   168篇
眼科学   47篇
药学   329篇
中国医学   18篇
肿瘤学   857篇
  2023年   55篇
  2022年   107篇
  2021年   218篇
  2020年   110篇
  2019年   145篇
  2018年   198篇
  2017年   145篇
  2016年   216篇
  2015年   228篇
  2014年   261篇
  2013年   314篇
  2012年   500篇
  2011年   537篇
  2010年   312篇
  2009年   251篇
  2008年   443篇
  2007年   434篇
  2006年   471篇
  2005年   436篇
  2004年   454篇
  2003年   430篇
  2002年   375篇
  2001年   107篇
  2000年   93篇
  1999年   122篇
  1998年   95篇
  1997年   87篇
  1996年   84篇
  1995年   80篇
  1994年   44篇
  1993年   58篇
  1992年   65篇
  1991年   34篇
  1990年   41篇
  1989年   42篇
  1988年   29篇
  1987年   28篇
  1986年   22篇
  1985年   20篇
  1984年   27篇
  1983年   18篇
  1982年   12篇
  1981年   15篇
  1979年   12篇
  1978年   10篇
  1974年   10篇
  1973年   10篇
  1972年   12篇
  1969年   11篇
  1968年   10篇
排序方式: 共有7907条查询结果,搜索用时 15 毫秒
61.
In this study, we clinically and radiographically evaluated open reduction with shortening of the femur in children more than 1 year old with refractory congenital dislocation of the hip. In 19 children (aged 1–4 years), 22 joints were operated on. The patients were followed-up for an average of 8.7 years (range, 2–13 years). Functional results were satisfactory in all joints, and differences in limb length were not significant. Radiographically, good results (grades I and II) were obtained in 16 of the 22 joints, according to Severin's criteria. This surgical procedure may be indispensable for treating refractory congenital dislocation of the hip in children over 1 year old. Received for publication on May 2, 1997; accepted June 3, 1998  相似文献   
62.

Purpose

Several video-assisted and robotic surgery techniques have been reported for resection of the thyroid and parathyroid glands. Our institute has started performing endoscopic thyroidectomy using the Lap-protector and E·Z-access system, referred to as E·Z-access using video-assisted neck surgery (EZ-VANS). In this report, we evaluate the safety and efficacy of this technique.

Methods

From January 2007 to September 2014, 110 patients underwent resection of a primary thyroid tumor, 73 who underwent a cervical collar incision (the Open group) and 37 underwent EZ-VANS (the EZ-VANS group).

Results

The average operating time was 159 and 172 min in the Open group and EZ-VANS group, respectively; the amount of blood loss was 46.5 and 54.7 ml, respectively; and the length of hospital stay after surgery was 4.3 and 5.2 days, respectively, with no significant differences observed between the two groups. The learning curve for the EZ-VANS technique was shorter than for open surgery.

Conclusions

We confirmed that the EZ-VANS technique is a safe and useful method for resection of benign and early malignant thyroid tumors.
  相似文献   
63.
Islet cell transplantation (ICTx) is one of the most effective treatments for type 1 diabetes and is less invasive compared to whole organ transplantation. The US has been the leader in the research and clinical applications of ICTx for the last 40 years. ICTx requires complex procedures, including pancreas procurement and preservation; pancreas digestion; islet purification; and transplantation. Even with the dramatic progresses in each of the procedures listed above, there are still challenges to make ICTx the standard therapy. These challenges are: (1) obtaining enough islets from a single donor and (2) preventing graft loss due to allogenic rejection and recurrence of autoimmune islet destruction. A new preservation strategy for pancreata and pancreatic ducts using ET-Kyoto solution as well as a new islet purification method using iodixanol has substantially improved islet yields. Continuous research to improve the efficacy of islet isolation will solve the issue of obtaining enough islets from a single donor. Immunological tolerance is an ideal solution for the issue of rejection and autoimmune recurrence and a regulatory T cell strategy seems promising. Moreover, the SUITO index is a simple and powerful tool to assess engrafted islet mass and is, therefore, useful for evaluating the efficacy of new immunosuppressant strategies. Once ICTx becomes a standard treatment, the donor shortage will become the next challenge. Marginal or living donor islet transplantations could help alleviate this issue; however, bio-artificial islet transplantation with animal islets could be the ultimate solution.  相似文献   
64.

Objective

To assess the value of applying MultiVane to liver T2-weighted imaging (T2WI) compared with conventional T2WIs with emphasis on detection of focal liver lesions.

Materials and Methods

Seventy-eight patients (43 men and 35 women) with 86 hepatic lesions and 20 pancreatico-biliary diseases underwent MRI including T2WIs acquired using breath-hold (BH), respiratory-triggered (RT), and MultiVane technique at 3T. Two reviewers evaluated each T2WI with respect to artefacts, organ sharpness, and conspicuity of intrahepatic vessels, hilar duct, and main lesion using five-point scales, and made pairwise comparisons between T2WI sequences for these categories. Diagnostic accuracy (Az) and sensitivity for hepatic lesion detection were evaluated using alternative free-response receiver operating characteristic analysis.

Results

MultiVane T2WI was significantly better than BH-T2WI or RT-T2WI for organ sharpness and conspicuity of intrahepatic vessels and main lesion in both separate reviews and pairwise comparisons (p < 0.001). With regard to motion artefacts, MultiVane T2WI or BH-T2WI was better than RT-T2WI (p < 0.001). Conspicuity of hilar duct was better with BH-T2WI than with MultiVane T2WI (p = 0.030) or RT-T2WI (p < 0.001). For detection of 86 hepatic lesions, sensitivity (mean, 97.7%) of MultiVane T2WI was significantly higher than that of BH-T2WI (mean, 89.5%) (p = 0.008) or RT-T2WI (mean, 84.9%) (p = 0.001).

Conclusion

Applying the MultiVane technique to T2WI of the liver is a promising approach to improving image quality that results in increased detection of focal liver lesions compared with conventional T2WI.  相似文献   
65.
Purpose  Patient-controlled epidural analgesia (PCEA) was developed for use after surgery for thoracic esophageal cancer to relieve wound pain, introduce early rehabilitation, and provide an uneventful postoperative recovery. Methods  This retrospective study investigated 22 patients who underwent esophageal surgery to determine the efficacy of postoperative management with PCEA. In the PCEA group (n = 12), patients had two epidural catheters inserted to cover both the thoracic and abdominal incision with a patient-controlled bolus capability. Results  Postoperative mechanical ventilation was administered in all cases in the control group (n = 10). On the other hand, this was only necessary in two patients in the PCEA group. The amount of time the patients stayed in the intensive care unit and the hospital was significantly shorter in the PCEA group than in the control group (P < 0.001 and P < 0.01, respectively). Respiratory complications occurred in four patients in the control group, and none in the PCEA group. The mean number of supplemental analgesics administered for breakthrough pain until the 7th postoperative day was 5.5 in the control group, and 1.3 in the PCEA group (P < 0.001). Conclusions  Early rehabilitation is facilitated with intensive PCEA, while it also improves postoperative management and reduces hospitalization after esophageal surgery.  相似文献   
66.
BACKGROUND CONTEXT: Although posterior lumbar interbody fusion (PLIF) for degenerative lumbar diseases is routine, there are few reports on double-level PLIF. PURPOSE: To evaluate the clinical outcomes of double-level PLIF. STUDY DESIGN/SETTING: A retrospective study of operated cases in Gifu, Japan. PATIENT SAMPLE: Nineteen patients (8 men and 11 women, 59.5+/-10.2 years) who underwent double-level PLIF between 1996 and 2001. OUTCOME MEASURES: Operation time, blood loss, complications, the Japanese Orthopaedic Association (JOA) score for back pain and lumbar sagittal alignment were evaluated. METHODS: Patients were examined retrospectively at follow-ups of 3.6+/-1.7 years. Primary diseases were spondylolisthesis, spinal canal stenosis, degenerative scoliosis and herniated intervertebral disc. Fusion areas were L3 to L5 in 15 cases and L4 to S1 in 4 cases. RESULTS: The mean JOA score increased from an initial score of 12.9+/-3.5 to 21.3+/-4.9 at the final follow-up. There was a positive correlation (R=0.718, p<.001) between the increase in lordotic angle and the increase in the JOA score. Several parameters suggested that the surgical invasiveness was not minimal. CONCLUSION: Double-level PLIF provided satisfactory results and preserved lumbar spine lordosis.  相似文献   
67.
The incidence and characteristics of microbleeds in hemodialysis (HD) patients were investigated to elucidate the clinical significance with T(2)(*)-weighted gradient-echo magnetic resonance (MR) imaging. The 57 patients with chronic renal failure maintained by HD had no previous history of stroke. The control group consisted of 53 patients without previous history of stroke or chronic renal failure. The incidence and the number of microbleeds were assessed in the HD and control groups. The findings of microbleeds with T(2)(*)-weighted gradient-echo MR imaging were compared with those of T(1)- and T(2)-weighted MR imaging in HD patients. The incidence of microbleeds was significantly greater in the HD patients compared with the control patients. T(2)(*)-weighted gradient-echo imaging revealed a total of 44 microbleeds in 11 HD patients. T(2)-weighted imaging demonstrated 13 of 44 microbleeds as hyperintensity, whereas T(1)-weighted imaging demonstrated 12 lesions as hypointensity. T(2)- and T(1)-weighted imagings did not demonstrate any findings in 31 and 32 lesions, respectively. T(2)(*)-weighted gradient-echo MR imaging is effective to detect microbleeds which may be a predictor of intracerebral hemorrhage in HD patients and should be included in the protocol for the study of cerebrovascular disease, because T(2)- and T(1)-weighted MR imaging recognizes microbleeds as lacunar infarction.  相似文献   
68.
PURPOSE: To evaluate the efficacy of hand-assisted laparoscopic radical nephrectomy (HALRN) in patients with localized stage T(1)/T(2) renal-cell carcinoma, we analyzed the clinical results of our patients treated in this way. PATIENTS AND METHODS: From March 1999 to March 2003, a total of 96 patients aged 28 to 86 years (mean 61 years) with clinical stage T(1)/T(2)N(0)M(0), pathologically confirmed renal-cell carcinoma underwent HALRN. The outcomes were compared with those of open radical nephrectomy, which was performed in 86 patients from November 1991 to February 1999 in our institution. Kaplan-Meier analysis was used to analyze survival. RESULTS: Ten patients (10.4%) had perioperative complications. During a mean follow-up of 25 months (range 6-54 months), no patients died of the cancer, although three patients had metastatic disease. The 4-year disease- free and overall survival rates were 88% and 100%, respectively. Seventy-eight patients who underwent open radical nephrectomy were followed for 38 to 156 months (median 86 months). Seventy-three survived without any recurrent disease, five survived with metastasis, and no patient died of metastatic disease. The 4-year disease-free and overall survival rates were 93% and 100%, respectively. CONCLUSIONS: Hand-assisted laparoscopic surgical management of T(1)/T(2) renal-cell carcinoma is feasible and safe. At our institution, HALRN confers long-term oncologic effectiveness equivalent to that of open radical nephrectomy.  相似文献   
69.

Purpose

The aim of this systematic review is to examine the available clinical evidence in the literature to support mesenchymal stem cell (MSC) treatment strategies in orthopaedics for cartilage defect regeneration.

Methods

The research was performed on the PubMed database considering the English literature from 2002 and using the following key words: cartilage, cartilage repair, mesenchymal stem cells, MSCs, bone marrow concentrate (BMC), bone marrow-derived mesenchymal stem cells, bone marrow stromal cells, adipose-derived mesenchymal stem cells, and synovial-derived mesenchymal stem cells.

Results

The systematic research showed an increasing number of published studies on this topic over time and identified 72 preclinical papers and 18 clinical trials. Among the 18 clinical trials identified focusing on cartilage regeneration, none were randomized, five were comparative, six were case series, and seven were case reports; two concerned the use of adipose-derived MSCs, five the use of BMC, and 11 the use of bone marrow-derived MSCs, with preliminary interesting findings ranging from focal chondral defects to articular osteoarthritis degeneration.

Conclusions

Despite the growing interest in this biological approach for cartilage regeneration, knowledge on this topic is still preliminary, as shown by the prevalence of preclinical studies and the presence of low-quality clinical studies. Many aspects have to be optimized, and randomized controlled trials are needed to support the potential of this biological treatment for cartilage repair and to evaluate advantages and disadvantages with respect to the available treatments.

Level of evidence

IV.  相似文献   
70.
To assess the biventricular response of the clearance rate of carbon-11 acetate as an index of myocardial oxidative metabolism to increase in work-load, dynamic positron emission tomography was performed at rest and during dobutamine infusion in 14 normal subjects. The clearance rate constant (Kmono) of the left ventricular (LV) myocardium increased during dobutamine infusion (0.112±0.020 min–1 vs 0.065±0.015 min–1 at rest) (P<0.001) in proportion to the increase in the pressure-rate product. Kmono in the right ventricular (RV) myocardium also increased (0.080±0.018 min–1 vs 0.034±0.013 min–1 at rest) (P<0.001), with an excellent correlation with the LV Kmono (r=0.920). The fact that the increase in RV Kmono during dobutamine infusion was greater (158%±81%) than that in LV Kmono (79%±39%) (P < 0.005) indicates a greater increase in oxidative metabolism in the RV in response to inotropic stimulation in normal subjects. Correspondence to: N. Tamaki  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