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   2440篇
  免费   124篇
  国内免费   3篇
耳鼻咽喉   10篇
儿科学   76篇
妇产科学   34篇
基础医学   384篇
口腔科学   23篇
临床医学   230篇
内科学   391篇
皮肤病学   72篇
神经病学   205篇
特种医学   149篇
外科学   445篇
综合类   17篇
一般理论   1篇
预防医学   187篇
眼科学   21篇
药学   143篇
中国医学   3篇
肿瘤学   176篇
  2023年   10篇
  2022年   11篇
  2021年   26篇
  2020年   9篇
  2019年   23篇
  2018年   30篇
  2017年   29篇
  2016年   32篇
  2015年   48篇
  2014年   58篇
  2013年   92篇
  2012年   103篇
  2011年   131篇
  2010年   88篇
  2009年   92篇
  2008年   140篇
  2007年   149篇
  2006年   158篇
  2005年   163篇
  2004年   140篇
  2003年   149篇
  2002年   156篇
  2001年   56篇
  2000年   45篇
  1999年   54篇
  1998年   30篇
  1997年   39篇
  1996年   23篇
  1995年   13篇
  1994年   21篇
  1993年   17篇
  1992年   23篇
  1991年   21篇
  1990年   22篇
  1989年   22篇
  1988年   19篇
  1987年   15篇
  1986年   28篇
  1985年   16篇
  1984年   12篇
  1980年   9篇
  1979年   13篇
  1975年   10篇
  1974年   8篇
  1973年   11篇
  1972年   12篇
  1969年   10篇
  1968年   10篇
  1967年   10篇
  1966年   8篇
排序方式: 共有2567条查询结果,搜索用时 15 毫秒
21.
Purpose

Posterior instrumentation is the state-of-the-art surgical treatment for fractures of the thoracic and lumbar spine. Options for pedicle screw placement comprise open or minimally invasive techniques. Open instrumentation causes large approach related muscle detachment, which minimally invasive techniques aim to reduce. However, concerns of accurate pedicle screw placement are still a matter of debate. Beside neurological complications due to pedicle screw malplacement, also affection of the facet joints and thus motion dependent pain is known as a complication. The aim of this study was to assess accuracy of pedicle screw placement concerning facet joint violation (FJV) after open- and minimally invasive posterior instrumentation.

Methods

A retrospective data analysis of postoperative computer tomographic scans of 219 patients (1124 pedicle screws) was conducted. A total of 116 patients underwent open screw insertion (634 screws) and 103 patients underwent minimally invasive, percutaneous screw insertion (490 screws).

Results

In the lumbar spine (segments L3, L4, L5), there were significantly more and higher grade (open = 0.55 vs. percutaneous = 1.2; p = 0.001) FJV’s after percutaneously compared to openly inserted screws. In the thoracic spine, no significant difference concerning rate and grade of FJV was found (p > 0.56).

Conclusion

FJV is more likely to occur in percutaneously placed pedicle screws. Additionally, higher grade FJV’s occur after percutaneous instrumentation. However, in the thoracic spine we didn’t find a significant difference between open and percutaneous technique. Our results suggest a precise consideration concerning surgical technique according to the fractured vertebrae in the light of the individual anatomic structures in the preop CT.

  相似文献   
22.
The outcome of 33 total hip arthroplasties using an acetabular reinforcement ring with hook for osteoarthritis associated with developmental dysplasia of the hip was reevaluated after a minimal follow-up of 10 years (average, 10.8 years). Most cases comprised Crowe type II (22 hips) and type III (7 hips) dysplasia. The mean D'Aubigné score increased from 7 to 15 points. Three revisions (9%) were performed for aseptic loosening, 2 of them had a structural autograft. None of the unrevised 30 acetabular reconstructions showed definite radiographic signs of loosening. These results compare favorably with the literature and the acetabular reinforcement ring with hook presents a versatile tool for acetabular bone stock deficiencies.  相似文献   
23.
Signaling through the epidermal growth factor receptor (EGFR) by ligands such as epidermal growth factor (EGF), transforming growth factor α (TGFA), and amphiregulin (AREG) has been reported to have effects on skeletal growth. The role of betacellulin (BTC), another EGFR ligand, in skeletal development and bone metabolism is unknown. In previous experiments, transgenic mice overexpressing BTC ubiquitously under the control of the chicken β‐actin promoter (BTC‐tg) exhibited stunted growth and disproportionately sized long bones. In this study, we performed a detailed phenotypic analysis of BTC‐tg mice at 3, 6, and 9 wk of age. Osteoblastic cells from transgenic mice showed strong expression of BTC as determined by Western blots and by immunohistochemistry on bone sections. In femurs of male and female BTC‐tg mice, we found reduced longitudinal bone growth and a pronounced increase in total volumetric BMD. The increased femoral BMD was mainly caused by augmented endocortical bone apposition and subsequent cortical bone thickening. In contrast, vertebral BMD was reduced in BTC‐tg mice of both sexes. An overall similar phenotype was found in 6‐mo‐old BTC‐tg mice. The increase in cortical bone mass in the appendicular skeleton of BTC‐tg mice was largely blocked when they were crossed into the EgfrWa5 background characterized by a dominant negative EGFR. Our study showed that overexpression of BTC results in an EGFR‐dependent upregulation of cortical bone mass in the appendicular skeleton of mice, uncovering a potential novel anabolic pathway for cortical bone.  相似文献   
24.
25.
The Spine Study Group (AG WS) of the German Trauma Association (DGU) presents its second prospective Internet-based multicenter study (MCS II) for the treatment of thoracic and lumbar spinal injuries. This second part of the study report focuses on the surgical treatment, course of treatment, and radiological findings in a study population of 865 patients. A total of 158 (18,3%) thoracic, 595 (68,8%) thoracolumbar, and 112 (12,9%) lumbar spine injuries were treated. Of these, 733 patients received operative treatment (OP group). Fifty-two patients were treated non-operatively and 69 patients were treated with kyphoplasty/vertebroplasty without additional instrumentation (Plasty group). In the OP group, 380 (51.8%) patients were instrumented from a posterior (dorsal) position, 34 (4.6%) from an anterior (ventral) position, and 319 (43.5%) cases with a combined posteroanterior procedure. Angular stable internal spine fixator systems were used in 86–97% of the cases for posterior and/or combined posteroanterior procedures. For anterior procedures, angular stable plate systems were used in a majority of cases (51.1%) for the instrumentation of mainly one or two segment lesions (72.7%). In 188 cases (53,3%), vertebral body replacement implants (cages) were used and were mainly implanted via endoscopic approaches (67,4%) to the thoracic spine and/or the thoracolumbar junction. The average operating time was 152 min in posterior-, 208 min in anterior-, and 298 min in combined postero-anterior procedures (p<0,001). The average blood loss was highest in combined operations, measuring 959 ml vs. 650 ml in posterior vs. 534 ml in anterior operations (p<0,001). Computer-assisted intraoperative navigation systems were used in 95 cases. At the time of hospital admission, 58,7% of the patients had spinal canal narrowing of an average of 36% (5–95%) at the level of their injury. The average spinal canal narrowing in patients with a complete spinal cord injury (Frankel/ASIA A) was calculated to be 70%, vs. 50% in patients with incomplete neurologic deficits (Frankel/ASIA B–D), and 20% in patients without neurologic deficits (Frankel/ASIS E; p<0,001). The average procedure in the plasty treatment subgroup was 50 min (18–145 min) to address one (n=59) or two (n=10) injured vertebral bodies. In patients with nonoperative treatment mainly three-point-corsets (n=36) were administered for a duration of 6–12 weeks. During their hospital stay 93 of 195 (44,7%) patients with initial neurologic deficits improved at least one Frankel/ASIA grade until the day of discharge. Two patients (0,2%) showed a neurologic deterioration. The highest rate of complete spinal cord injury (n=36, 23%) was associated with thoracic spine injuries. Nine (1%) patients died during the initial course of treatment. A total of 105 (14,3%) cases with intraoperative (n=56) and/or postoperative complications (n=69) were registered. The most common intraoperative complication was bleeding (n=35, 4,8%). A higher relative frequency of intraoperative complications was noticed in combined (n=34, 10,7%) vs. isolated posterior (n=22, 5,9%; p=0,021) procedures. The most common postoperative complication was associated with wound healing problems in 14 (1,9%) patients. Except in the non-operative treatment subgroup, a correction of the posttraumatic measured radiological deformity was achieved to a different extent within every treatment subgroup. There were no statistically significant differences between the postoperative radiological results of the treatment subgroups (dorsal vs. combination), taking into consideration the influence of relevant parameters such as different fracture types, patient age, and the amount of posttraumatic deformity (p=0,34, ANOVA).  相似文献   
26.

Background.

The aim of this study was to test the validity of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire, Core Module (QLQ‐C30) and Head and Neck Module (QLQ‐H&N35) for patients who have undergone surgery due to laryngeal cancer.

Methods.

A total of 323 patients from 6 different centers in Germany who had been operated on completed the QLQ‐C30 and the QLQ‐H&N35 in addition to being surveyed in a personal interview.

Results.

Multitrait scaling analysis confirmed the proposed scale structure of both questionnaires. Cronbach's alpha of the QLQ‐C30 scales ranged from 0.64 (Cognitive Functioning) to 0.94 (Global Health Status); the alpha of the QLQ‐H&N35 ranged from 0.55 (Speech) to 0.90 (Sexuality). Known‐groups comparisons showed multiple differences in sociodemographic and clinical variables.

Conclusion.

It can be concluded that the QLQ‐H&N35, in conjunction with the QLQ‐C30, is a reliable instrument that is able to differentiate between diverse groups of patients with laryngeal cancer after surgery. © 2008 Wiley Periodicals, Inc. Head Neck, 2009  相似文献   
27.
BACKGROUND: High-dose chemotherapy followed by autologous blood stem cell transplantation induces remission of plasma cell dyscrasia in patients with AL amyloidosis. The impact of this treatment on the glomerular amyloid mass is still unknown. METHODS: In the present study, the quantity of the renal amyloid mass before and more than 3 years after high-dose melphalan treatment and autologous blood stem cell transplantation was assessed in two patients. At the time of the second renal biopsy, both patients were in complete remission without detectable serum and urinary monoclonal IgA-lambda and a normal percentage of plasma cells in the bone marrow. RESULTS: In both patients with biopsy-proven AL amyloidosis, urinary protein excretion decreased from 7 g/24 h to <2 g/24 h more than 3 years after autologous blood stem cell transplantation. In contrast, glomerular amyloid deposits persisted, as shown in the second biopsy. CONCLUSION: Despite complete remission of the plasma cell dyscrasia and improvement of glomerular permeability, the amount of glomerular amyloid mass did not regress.  相似文献   
28.
Microsurgical management of the diabetic foot   总被引:1,自引:0,他引:1  
Allthough there has been dramatic progress in limb salvage in recent decades, management of nonhealing wounds in diabetic patients continues to present a dilemma for the reconstructive surgeon. However, the acceptance of free-flap resurfacing of diabetic foot ulcers has increased in recent years. This study reviews 10 microvascular free muscle flaps in nine patients over a mean follow-up period of 44 months. Five patients had evidence of peripheral vascular disease. There was one flap loss, and nine flaps were transferred successfully. No perioperative mortality was encountered. The operations required a long, costly hospitalization (average hospital stay was 40 days). Seven of eight patients whose flaps survived had complications related to the free-flap recipient site. These seven patients underwent 20 secondary surgical procedures due to arterial and venous thrombosis, partial necrosis of the skin grafts, minor local infections, and gangrene or necrosis of the remaining toes. In three patients, progressive ischemic necrosis of the remaining toes, with total survival of the flap, was attributed to a microvascular steal phenomenon. However, all eight patients whose flaps survived subsequently ambulated on their flaps. The study demonstrates that microvascular surgery may result in functional lower-extremity salvage in diabetic patients with foot wounds that are not treatable by local flaps or skin grafts, and are destined for amputation.  相似文献   
29.

OBJECTIVE

To assess the pathological features of Gleason score 6 prostate cancers after radical prostatectomy in the low (<4 ng/mL) and intermediate range of prostate‐specific antigen level (4–10 ng/mL), as such prostate cancers are considered to be well differentiated tumours with a low risk for recurrence after therapy.

PATIENTS AND METHODS

In all, 1354 patients with T1c prostate cancer and PSA levels of <10.0 ng/mL had a radical retropubic prostatectomy. Patients with Gleason score 6 tumours were divided into two groups, those with PSA levels of <4 and 4.0–10.0 ng/mL. Extracapsular extension, positive surgical margins, biochemical recurrence (BCR) and mean time to BCR were evaluated.

RESULTS

Of the 1354 patients, there were 437 (32.3%) with Gleason score 6 prostate cancers. Patients in the low PSA group had less extraprostatic disease than those with a higher level (5.9% vs 14.5%) and both groups had an almost equal proportion of positive surgical margins (9.4% vs 11.0%). In the low PSA group there was statistically significantly shorter BCR than in the high PSA group, with a mean time to BCR of 1.7 vs 3.1 years.

CONCLUSIONS

These results show a statistically significantly higher rate of extraprostatic disease and earlier BCR in men with a high than a low PSA level even in Gleason score 6 prostate cancer. As the rate of BCR and extracapsular extension are significantly related to prostate cancer mortality, these findings further support the concept of screening using low PSA levels.  相似文献   
30.
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