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   1440篇
  免费   126篇
  国内免费   11篇
耳鼻咽喉   9篇
儿科学   50篇
妇产科学   41篇
基础医学   160篇
口腔科学   37篇
临床医学   120篇
内科学   307篇
皮肤病学   13篇
神经病学   235篇
特种医学   97篇
外科学   177篇
综合类   16篇
预防医学   83篇
眼科学   9篇
药学   104篇
中国医学   1篇
肿瘤学   118篇
  2022年   12篇
  2021年   18篇
  2020年   12篇
  2019年   30篇
  2018年   27篇
  2017年   19篇
  2016年   32篇
  2015年   34篇
  2014年   54篇
  2013年   43篇
  2012年   62篇
  2011年   68篇
  2010年   46篇
  2009年   50篇
  2008年   59篇
  2007年   90篇
  2006年   65篇
  2005年   50篇
  2004年   48篇
  2003年   56篇
  2002年   36篇
  2001年   24篇
  2000年   19篇
  1999年   36篇
  1998年   40篇
  1997年   23篇
  1996年   28篇
  1995年   25篇
  1994年   15篇
  1993年   13篇
  1992年   16篇
  1991年   13篇
  1990年   19篇
  1989年   20篇
  1988年   28篇
  1987年   26篇
  1986年   20篇
  1985年   16篇
  1984年   16篇
  1982年   11篇
  1981年   17篇
  1980年   14篇
  1979年   15篇
  1978年   11篇
  1977年   10篇
  1976年   14篇
  1974年   12篇
  1972年   10篇
  1970年   9篇
  1969年   12篇
排序方式: 共有1577条查询结果,搜索用时 15 毫秒
11.
Summary We hypothesized that combining clinical risk factors (CRF) with the heel stiffness index (SI) measured via quantitative ultrasound (QUS) would improve the detection of women both at low and high risk for hip fracture. Categorizing women by risk score improved the specificity of detection to 42.4%, versus 33.8% using CRF alone and 38.4% using the SI alone. This combined CRF-SI score could be used wherever and whenever DXA is not readily accessible. Introduction and hypothesis Several strategies have been proposed to identify women at high risk for osteoporosis-related fractures; we wanted to investigate whether combining clinical risk factors (CRF) and heel QUS parameters could provide a more accurate tool to identify women at both low and high risk for hip fracture than either CRF or QUS alone. Methods We pooled two Caucasian cohorts, EPIDOS and SEMOF, into a large database named “EPISEM”, in which 12,064 women, 70 to 100 years old, were analyzed. Amongst all the CRF available in EPISEM, we used only the ones which were statistically significant in a Cox multivariate model. Then, we constructed a risk score, by combining the QUS-derived heel stiffness index (SI) and the following seven CRF: patient age, body mass index (BMI), fracture history, fall history, diabetes history, chair-test results, and past estrogen treatment. Results Using the composite SI-CRF score, 42% of the women who did not report a hip fracture were found to be at low risk at baseline, and 57% of those who subsequently sustained a fracture were at high risk. Using the SI alone, corresponding percentages were 38% and 52%; using CRF alone, 34% and 53%. The number of subjects in the intermediate group was reduced from 5,400 (including 112 hip fractures) and 5,032 (including 111 hip fractures) to 4549 (including 100 including fractures) for the CRF and QUS alone versus the combination score. Conclusions Combining clinical risk factors to heel bone ultrasound appears to correctly identify more women at low risk for hip fracture than either the stiffness index or the CRF alone; it improves the detection of women both at low and high risk.  相似文献   
12.
OBJECTIVE: In 4-10% of cases of renal cell carcinoma (RCC), involvement of the inferior vena cava (IVC) is present. IVC involvement may be due to either a pure thrombus or tumor extension. This study indicates that there is no significant difference in survival rates between patients with thrombus and those with infiltration of the IVC. MATERIAL AND METHODS: The records of 84 patients who presented to our institution with RCC and IVC involvement and received surgical treatment between July 1973 and June 2006 were examined. The postoperative observation period was 120 months. Statistical analysis was performed using the Kaplan-Meier method and the log-rank test. RESULTS: Sixty-one patients demonstrated thrombus involvement of the IVC, while the remaining 23 exhibited infiltration. Over the observation period, an average survival time of 64.0 months was observed. The median survival time was 35.2 months. No significant difference in survival rates was observed between patients with thrombus and those with malignant infiltration of the IVC. CONCLUSIONS: It is stated in the contemporary literature that IVC infiltration is an important prognostic factor in cases of RCC. This study indicates that there is no significant difference in survival rates between patients with thrombus and those with infiltration of the IVC. Lymph node metastases and undifferentiated RCC remain the only important prognostic factors that have a significant influence on the general survival of a patient.  相似文献   
13.
ObjectiveTo evaluate pain and disability at the time of knee replacement surgery for osteoarthritis.MethodsIn this multicenter cross-sectional study, 299 patients at 12 orthopedic surgery centers in Lyon, France were evaluated on the day before knee replacement surgery. Pain severity was assessed on a visual analog scale (VAS) and function using the Lequesne index and the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC).ResultsThere were 207 women and 92 men with a mean age of 73 years. Mean (±SD) VAS pain score upon walking was 55.8 ± 24 mm. Compared to patients with very severe disability (Lequesne index > 12), those with mild-to-severe disability (Lequesne index  12) were more likely to be older than 70 years (odds ratio [OR], 2.85; 95% confidence interval [95%CI], 1.25–5) and male (OR, 2.5; 95%CI, 1.3–5); they were less likely to have a body mass index > 27 kg/m2 (OR, 2.2; 95%CI, 1.3–3.3) and to engage in sporting activities (OR, 3.3; 95%CI, 1.4–10).ConclusionPatients about to undergo knee replacement surgery had high levels of pain and disability, with little variation across centers. Nevertheless, the severity of pain and disability may depend in part on age, gender, body mass index, and sporting activities, which probably influence the decision to perform knee replacement surgery.  相似文献   
14.
Background The optimal strategy for incorporating lymphatic mapping and sentinel lymph node biopsy into the management of breast cancer patients receiving neoadjuvant chemotherapy remains controversial. Previous studies of sentinel node biopsy performed following neoadjuvant chemotherapy have largely reported on patients whose prechemotherapy, pathologic axillary nodal status was unknown. We report findings using a novel comprehensive approach to axillary management of node-positive-patients receiving neoadjuvant chemotherapy. Methods We evaluated 54 consecutive breast cancer patients with biopsy-proven axillary nodal metastases at the time of diagnosis that underwent lymphatic mapping with nodal biopsy as well as concomitant axillary lymph node dissection after receiving neoadjuvant chemotherapy. All cases were treated at a single comprehensive cancer center between 2001 and 2005. Results The sentinel node identification rate after delivery of neoadjuvant chemotherapy was 98%. Thirty-six patients (66%) had residual axillary metastases (including eight patients that had undergone resection of metastatic sentinel nodes at the time of diagnosis), and in 12 cases (31%) the residual metastatic disease was limited to the sentinel lymph node. The final, post-neoadjuvant chemotherapy sentinel node was falsely negative in three cases (8.6%). The negative final sentinel node accurately identified patients with no residual axillary disease in 17 cases (32%). Conclusions Sentinel lymph node biopsy performed after the delivery of neoadjuvant chemotherapy in patients with documented nodal disease at presentation accurately identified cases that may have been downstaged to node-negative status and can spare this subset of patients (32%) from experiencing the morbidity of an axillary dissection.  相似文献   
15.
Surgery is still a main therapeutic option in breast cancer treatment. Nowadays, methods of resection and reconstruction vary according to different tumors and patients. This review presents and discusses standards of care and arising questions on how radical primary breast cancer surgery should be according to different clinical situations. In most early breast cancer patients, breast conservation is the method of choice. The discussion on resection margins is still controversial as different studies show conflicting results. Modified radical mastectomy is the standard in locally advanced breast cancer patients, although there are different promising approaches to spare skin or even the nipple-areola complex. A sentinel node biopsy is the standard of care in clinically node-negative invasive breast cancer patients, whereas the significance of axillary lymphonodectomy seems to be questioned through a number of different findings. Although there are interesting findings to modify surgical approaches in very young or elderly breast cancer patients, it will always be an individualized approach if we do not adhere to current guidelines. Up to date, there are no special surgical procedures in BRCA mutation carriers or patients of high-risk families.  相似文献   
16.

Purpose

The increasing detection of adrenal tumors and the availability of a more sophisticated biochemical work-up leading to rising numbers of sub-clinical Conn’s and Cushing’s syndromes coincide with a rising number of adrenalectomies worldwide. The aim of our study was to report a single institution’s experience with adrenal surgery.

Methods

We report data of 528 adrenalectomies, operated at our institution before and after the onset of minimally invasive endoscopic surgery (1986–1994, 1995–2008). Gender, age, indication, imaging, surgical approach, operating time, histology, tumor size, hospital stay, and complications were analyzed retrospectively.

Results

A total of 478 patients underwent adrenal surgery during the time observed. The average number of yearly adrenalectomies increased from 14 to 21 (p?=?0.001) after the onset of laparoscopic surgery. Imaging techniques showed a significant shift towards magnetic resonance imaging (p?<?0.001) and preoperative assessment of tumor size was significantly correlated to malignancy: 10.8?% (11/102) and 42?% (21/50) of tumors measuring 4–6?cm and ≥6 cm, respectively, were malignant in the final histology report (p?<?0.001). Patients operated by minimally invasive endoscopy were significantly younger (mean 49.4?years, p?=?0.046), had significantly shorter operating times (mean 118?min, p?<?0.001), had shorter hospital stays (mean 7.1?days, p?<?0.001), and had less complications (6.9?%, p?=?0.004) compared to patients resected through open procedures.

Conclusion

Although adrenalectomy rates increased and minimally invasive endoscopic surgery reduced hospital stay and complications at our institution, the yearly number of procedures was still low with often high surgical complexity. We therefore believe that adrenal surgery remains a highly specialized procedure that should preferably be performed at endocrine surgery centers.  相似文献   
17.
Strahlentherapie und Onkologie - The purpose of the present study was to evaluate the clinical outcome of CT-guided high-dose-rate brachytherapy (CT-HDRBT) in patients with unresectable...  相似文献   
18.
Femoral vein occlusion is not a common complication even after repeated hernia repair. We describe a case of a 14-year-old boy with a visible and soft, yet irreducible, mass below the inguinal ligament after 3 previous inguinal hernia repairs and heart catheterization in infancy. Further examination showed dilated venous collaterals, bypassing an occluded common femoral vein via the testicular sheaths and across the pelvic floor. We discuss etiology, diagnostic pitfalls, therapeutic options, and possible future complications, with a literature review.  相似文献   
19.
RATIONALE: Hip fractures can be separated into cervical and trochanteric fractures. Trochanteric fractures have been associated with up to twice the short-term mortality of cervical fractures in the elderly. There is also evidence suggesting that the mechanisms are different. Evidence from the literature remains limited on the predictive power of bone mineral density (BMD) and quantitative ultrasounds (QUS) for both types of hip fractures. METHODS: 5703 elderly women aged 75 years or more, who were recruited from the voting lists in the EPIDOS study, and had baseline calcaneal ultrasounds (QUS) and DXA measurements at the hip and the whole body, were analyzed in this paper. Among those, 192 hip fractures occurred during an average follow-up of 4 years, 108 cervical and 84 trochanteric fractures. RESULTS: Femoral neck, trochanteric and whole body BMD were able to predict trochanteric hip fracture (RR's and 95% CI were, respectively, 3.2 (2.4-4.2); 4.8 (3.5-6.6); and 2.8 (2.2-3.6)) more accurately than cervical fractures (respectively, 2.1 (1.7-2.7); 2.3 (1.8-3.0); 1.2 (1.0-1.6)). All ultrasound parameters, SOS, BUA, and stiffness index (SI) were significant predictors of trochanteric (RR's respectively 3.0 (2.2-4.1), 2.5(2.0-3.1), and 3.5(2.6-4.7)) but not cervical fractures. After adjustment for femoral neck or trochanteric BMD ultrasound parameters were still significant predictors of trochanteric fracture, and stiffness tended to be a better predictor of trochanteric fractures than either BUA or SOS with a relative risk of 2.25 (1.6-3.1). CONCLUSIONS: A significant decrease of all bone measurements, BMD and QUS, was highly predictive of trochanteric fractures, whereas a decrease of femoral neck and trochanteric BMD were only associated with a slight increase in cervical fracture risk and a low total body BMD or QUS parameters were not significant predictors of cervical fractures. In women who sustained a hip fracture, the decrease of BMD and QUS values increases the risk of trochanteric fracture as compared to cervical fracture. Trochanteric fractures were mostly a consequence of a generalized low BMD and QUS, whereas other parameters might be involved in cervical fractures.  相似文献   
20.
The adequacy of retrograde delivery of cardioplegic solution to the right ventricle and interventricular septum is controversial. To address this issue quantitatively, we infused blood cardioplegic solution labeled with radioactive microspheres (15 microns diameter) into the coronary sinus (n = 8 dogs) at a pressure of 51 +/- 1 mm Hg (mean +/- standard error of the mean) to be compared with the same quantity of labeled cardioplegic solution (20 ml/kg) delivered through the aorta (n = 6 dogs) at 97 +/- 7 mm Hg. Both methods of delivery produced cardiac arrest, but retrograde infusion required a significantly longer time to complete the infusion (6.2 +/- 0.8 minutes versus 1.5 +/- 0.1 minutes, p less than 0.01). Greater than 99% of the microspheres passing through the vasculature of the left ventricle were trapped in the left ventricular myocardium with antegrade infusion, and the distribution of the cardioplegic solution was uniform. Antegrade delivery (cardioplegic flow x infusion time) averaged approximately 3.0 to 4.0 ml/gm, except at the apex, where delivery averaged approximately 2.0 ml/gm. With retrograde infusion, 93% of the microspheres perfusing the left ventricle were trapped and delivery of the cardioplegic solution was not uniform. In the anterolateral free wall, delivery of cardioplegic solution averaged between 1.5 and 2.9 ml/gm (p less than 0.001 compared with antegrade) and only 0.6 to 0.8 ml/gm in the posteroseptal region of the basal left ventricle (p less than 0.001 compared with the antegrade group and anterolateral samples of the retrograde group). In the middle portion of the right ventricle, antegrade trapping of microspheres was 99% and delivery of cardioplegic solution averaged approximately 2.0 ml/gm. With retrograde delivery, only 16.5% (range 11.8% to 26.0%) of the microspheres passing through the right ventricular vasculature were trapped in the right ventricular myocardium, which indicates that substantial shunting had occurred. Corrected for the high shunt fraction, retrograde delivery of cardioplegic solution to the middle portion of the right ventricle averaged only 0.5 ml/gm (p less than 0.01). Retrograde delivery to the atrial septum and right atrium was also low. Because retrograde delivery of cardioplegic solution was markedly nonuniform, we conclude that inadequate cardioplegic delivery to the middle portion of the right ventricle and posteroseptal portion of the left ventricle could result with cardioplegic infusion through the coronary sinus.  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