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   4410篇
  免费   253篇
  国内免费   50篇
耳鼻咽喉   13篇
儿科学   124篇
妇产科学   30篇
基础医学   617篇
口腔科学   86篇
临床医学   270篇
内科学   1209篇
皮肤病学   23篇
神经病学   423篇
特种医学   181篇
外科学   812篇
综合类   19篇
预防医学   82篇
眼科学   30篇
药学   224篇
中国医学   6篇
肿瘤学   564篇
  2023年   39篇
  2022年   67篇
  2021年   134篇
  2020年   71篇
  2019年   85篇
  2018年   143篇
  2017年   89篇
  2016年   128篇
  2015年   133篇
  2014年   177篇
  2013年   193篇
  2012年   373篇
  2011年   368篇
  2010年   188篇
  2009年   161篇
  2008年   270篇
  2007年   311篇
  2006年   277篇
  2005年   225篇
  2004年   238篇
  2003年   264篇
  2002年   210篇
  2001年   52篇
  2000年   64篇
  1999年   56篇
  1998年   63篇
  1997年   40篇
  1996年   37篇
  1995年   35篇
  1994年   23篇
  1993年   29篇
  1992年   36篇
  1991年   9篇
  1990年   9篇
  1989年   14篇
  1988年   12篇
  1987年   14篇
  1986年   3篇
  1985年   8篇
  1984年   13篇
  1983年   11篇
  1982年   6篇
  1981年   3篇
  1977年   4篇
  1976年   6篇
  1975年   3篇
  1969年   3篇
  1968年   2篇
  1967年   2篇
  1966年   2篇
排序方式: 共有4713条查询结果,搜索用时 11 毫秒
101.

Background

Two-dimensional imaging is not adequate for evaluating ossification of the posterior longitudinal ligament (OPLL). This study was designed to evaluate the accuracy of a novel computed tomography (CT)-based three-dimensional (3D) analysis method that we had devised to measure volume changes in OPLL.

Subjects and methods

Twenty OPLL patients (12 male and 8 female; mean age 63.6 years) who were being followed conservatively were examined twice with an interval of at least 1 year between the two scans. The mean interval was 22 (range 12–45) months. A 3D model was created with DICOM data from CT images, using the MIMICS® software to calculate the volume. The mean ossification volume was determined from two measurements. Since ossification size varies widely, evaluation of change in volume is generally affected by the original size. Therefore, the change in ossification volume between the first and second CT examinations was calculated as the annual rate of progression.

Results

The type of OPLL was classified as continuous in 3 patients, segmented in 3, and mixed in 14. The mean ossification volume was 1,831.68 mm3 at the first examination and 1,928.31 mm3 at the second, showing a significant mean increase in ossification volume. The mean annual rate of lesion increase was 3.33 % (range 0.08–7.79 %).

Conclusion

The 3D method used allowed detailed OPLL classification and quantification of change in the ossified volume. Thus, this method appears to be very useful for quantitative evaluation of OPLL with only minimal measurement error.  相似文献   
102.

Background

Pre- and postoperative knee kinematics in unicompartmental knee arthroplasty (UKA) can be theoretically related to clinical outcome and longevity after UKA with regard to ligament function and the degree of arthritic changes. However, the preoperative knee kinematics of patients indicated for UKA remain to be elucidated, and it is also unclear whether the preoperative kinematics can be maintained by the UKA procedure. The objective of this study was to examine the in vivo pre- and postoperative three-dimensional knee kinematics in UKA while referencing the normal knee kinematics reported in our previous study.

Methods

We analyzed the knee kinematics in 17 knees (14 patients) undergoing UKA via a three-dimensional to two-dimensional registration technique employing femoral condylar translation and femoral axial rotation. The pre- and postoperative knee kinematics during squat motion were evaluated in the same subjects, employing consistent evaluation parameters.

Results

On average, both pre- and postoperative knee kinematics in the range 10–100° of knee flexion demonstrated near-consistent femoral external rotation and anterior translation of the medial condyle and posterior translation of the lateral condyle. However, the mean femoral external rotation angle and the posterior translation of the lateral condyle postoperatively were significantly smaller than the values observed preoperatively.

Discussion

Although the patterns of preoperative knee motion were similar to those seen in normal knees, the magnitude of this motion varied widely between patients, so it was not necessarily representative of normal knees. These variations may be due to the varying degrees of arthritic changes caused by osteoarthritis. Although the patterns of knee kinematics were largely maintained by the UKA procedure, the causes of the significant reductions in the magnitude of motion upon performing the UKA procedure should be investigated in subsequent studies with a larger number of patients.  相似文献   
103.
104.
The objective of this study was to record the clinical course of osteoporosis over time in Japanese women. We hypothesized that successful control of acute pain associated with osteoporosis will allow better treatment for health-related problems. To confirm this working hypothesis, we developed the Japan Questionnaire for Osteoporotic Pain (JQ22) to measure health status associated with osteoporosis. We examined the validity and reliability of the JQ22 compared with the current gold standard scale for back pain, the Roland Morris questionnaire (RDQ). A total of 125 women who were more than 65 years old, had an acute back pain episode, and had a fragile vertebral fracture confirmed by X-ray and clinical signs, participated in this study. The psychometric analyses for validity and reliability were tested for the JQ22 and the RDQ. The time course up to 6 weeks was observed by investigating both changes in pain characteristics and its influence on related activities and social participation. Cronbach’s alpha coefficient was 0.979 and 0.919 for the JQ22 and RDQ, respectively. The Akaike Information Criterion (AIC) indicated that the JQ22 items were separated into four domains, which were sequentially arranged at the baseline and subsequently changed. This structure reflected osteoporotic back characteristics covering a range from pain to social activities. The JQ22 was shown to be a valid and reliable scale for patient-based measurement of osteoporotic back pain. It also revealed both changes in pain characteristics and the influence of pain on related activities and participation.  相似文献   
105.
106.

Background

Downstream activation through receptor tyrosine kinases (RTKs) plays important roles in carcinogenesis. In this study, we assessed the clinical involvement of Axl, an RTK, and its ligand, Gas6, in surgically treated lung adenocarcinoma.

Methods

Axl and Gas6 mRNA and protein expression levels were quantified using quantitative real-time polymerase chain reaction and immunohistochemistry, respectively, in completely resected lung adenocarcinoma tissues (n = 88) and were evaluated for correlation with clinicopathologic features and patient survival.

Results

Higher expressions of Axl mRNA/protein and Gas6 protein were significantly related to worse clinicopathological features and prognosis (5-year overall survival rates: Axl mRNA low: 72.3 %, high: 49.7 %, P = 0.047; Axl protein low: 77.5 %, high: 38.6 %, P < 0.001; and Gas6 protein low: 70.5 %, high: 48 %, P = 0.042). On the contrary, higher Gas6 mRNA expression was related to better clinicopathological features and prognosis (5-year overall survival rates: Gas6 mRNA low: 59.2 %, high: 81.8 %, P = 0.054). Multivariate analysis suggests that high Axl mRNA expression may be an independent factor for poor patient prognosis (P = 0.04).

Conclusions

In lung adenocarcinoma, Axl and Gas6 expression levels were associated with tumor advancement and patient survival, thus rendering them as reliable biomarkers and potential targets for treatment of lung adenocarcinoma.
  相似文献   
107.
This report describes case series of the femoral head fractures associated with fracture-dislocation of the hip joint to evaluate the mid- and long-term outcomes and to highlight the surgical technique of fixation of the femoral head from the posterior trochanteric flip osteotomy approach. Twelve patients (6 men and 6 women) with dislocated femoral head fractures (mean age at the time of injury, 56 years; range, 23–80) were followed up for mean period of 9.7 years (range, 5–20). All dislocations were reduced within less than 6 h after the injury. The type of femoral head fracture was classified according to the Pipkin classification on radiographs and CT. Five patients were classified as type I, 2 as type II, 2 as type III, and 3 as type IV. The clinical and radiological outcomes were assessed by Thompson and Epstein’s regimen. Excluding 2 patients with Pipkin type III, the outcome of 9 patients was excellent/good, and poor in 1. The latter patient sustained Pipkin type IV and developed osteoarthritis 1 year after surgery and consequently required total hip arthroplasty. We conclude that small fragment of the femoral head less than 1 cm can be removed, while larger fragments should be fixed by bioabsorbable screws or pins in all types of femoral head fractures. In Pipkin type IV fractures, surgeons should always take anatomical reduction in the acetabulum into consideration during surgery.  相似文献   
108.

Purpose

Cardiac surgery for the patients with advanced liver cirrhosis is still challenging. High mortality has been reported in the literature. We evaluate the clinical outcome of cardiac surgery in patients with advanced liver cirrhosis.

Methods

Patients with advanced liver cirrhosis who underwent cardiac surgery between October 1999 and April 2009 were reviewed. The severity of liver cirrhosis was assessed using Child-Pugh class, Child-Pugh score, and MELD score. Advanced liver cirrhosis was defined as Child-Pugh class B or C. Cardiopulmonary bypass (CPB) was carried out at higher flow rate (2.4–3.2 L/min/m2), and hematocrit (25–30 %). Moderate and more tricuspid regurgitation were aggressively treated. Dilutional ultrafiltration was performed at the termination of CPB.

Results

Eighteen patients (mean age 70 years, male:female = 14:4) were identified. Twelve patients had hepatitis virus infection and 6 cases were alcohol-related. Fourteen patients were graded as Child-Pugh class B and 4 in class C. Seventeen patients underwent cardiac surgery with the use of cardiopulmonary bypass, and 1 patient underwent off-pump coronary artery bypass surgery. The overall mortality rate was 17 % (3 of 18). The cause of death was liver failure, esophageal variceal bleeding and bacteremia. The mortality of redo surgery was high (50 %). The incidence of postoperative liver failure was 11 % (2 of 18). Child-Pugh class or score was not correlated with hospital mortality. MELD score was significantly higher in hospital mortality (10.8 ± 4.0 vs. 17.3 ± 2.1, p = 0.001).

Conclusions

Although the mortality of redo surgery was high, cardiac surgery could be safely performed in selected patients with advanced liver cirrhosis.  相似文献   
109.
Objective:To develop surgical stents for cone-beam computed tomography (CBCT) 3-dimensional (3D) image-based stent-guided orthodontic miniscrew implantation and to evaluate its accuracy.Materials and Methods:Ten surgical stents were fabricated with stereolithographic appliances (SLAs) according to 3D CBCT image-based virtual implantation plans. Thirty self-drilling miniscrews were implanted at two to three positions on each side of the maxillary or mandibular posterior arches in three phantoms: 20 guided by 10 surgical stents in two phantoms (stent group) and 10 guided freehand in one phantom (freehand group). Six parameters (mesiodistal and vertical deviations at the corona and apex and mesiodistal and vertical angular deviations) were measured to compare variations between the groups.Results:No root damage was found in the stent group, whereas four of 10 miniscrews contacted with roots in the freehand group. In the stent group, deviations in the mesiodistal and vertical directions were 0.15 ± 0.09 and 0.19 ± 0.19 mm at the corona, respectively, and 0.28 ± 0.23 and 0.33 ± 0.25 mm at the apex, respectively; angular deviations in the mesiodistal and vertical directions were 1.47° ± 0.92° and 2.13° ± 1.48°, respectively. In the freehand group, the corresponding results were 0.48 ± 0.46 mm and 0.94 ± 0.87 mm (corona), 0.81 ± 0.61 mm and 0.78 ± 0.49 mm (apex), and 7.49° ± 6.09° and 6.31° ± 3.82°. Significant differences were found in all six parameters between the two groups (Student''s t-test, P < .05).Conclusions:3D CBCT image-based SLA-fabricated surgical stents can provide a safe and accurate method for miniscrew implantation.  相似文献   
110.
This article describes the foundation of a psychoanalytic institute in Japan and how its creation was based on the experience of training at the William Alanson White Institute. The process of starting a new institute is compared to the stages of growing plants, including planting seeds, sprouting, pruning, and transplanting. Creating an “ideal” institute requires a belief in education, the ability to find joy in relating to colleagues, and a capacity to deal with the evaluation process and with healthy tensions among subgroups.  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