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   7452篇
  免费   387篇
  国内免费   37篇
耳鼻咽喉   32篇
儿科学   160篇
妇产科学   67篇
基础医学   1309篇
口腔科学   266篇
临床医学   508篇
内科学   1546篇
皮肤病学   229篇
神经病学   845篇
特种医学   449篇
外科学   997篇
综合类   43篇
一般理论   2篇
预防医学   267篇
眼科学   99篇
药学   555篇
中国医学   11篇
肿瘤学   491篇
  2022年   36篇
  2021年   61篇
  2020年   72篇
  2019年   91篇
  2018年   113篇
  2017年   97篇
  2016年   111篇
  2015年   154篇
  2014年   242篇
  2013年   294篇
  2012年   396篇
  2011年   417篇
  2010年   305篇
  2009年   286篇
  2008年   427篇
  2007年   475篇
  2006年   477篇
  2005年   496篇
  2004年   469篇
  2003年   488篇
  2002年   495篇
  2001年   98篇
  2000年   87篇
  1999年   134篇
  1998年   130篇
  1997年   100篇
  1996年   88篇
  1995年   78篇
  1994年   71篇
  1993年   57篇
  1992年   56篇
  1991年   52篇
  1990年   44篇
  1989年   39篇
  1988年   33篇
  1987年   56篇
  1986年   31篇
  1985年   44篇
  1984年   30篇
  1983年   33篇
  1982年   41篇
  1981年   34篇
  1980年   36篇
  1978年   38篇
  1977年   30篇
  1976年   40篇
  1975年   27篇
  1974年   40篇
  1973年   31篇
  1970年   30篇
排序方式: 共有7876条查询结果,搜索用时 15 毫秒
91.

A prospective study of 1,017 patients who received MIOM during spine surgery procedures between March 2000 and December 2005. To determine the sensitivity and specificity of MIOM techniques used to monitor spinal cord and nerve roots function during spine surgery. MIOM has become a widely used method of monitoring neural function during spine surgery. Several techniques only monitor either ascending or descending pathways and thus may not provide sensitive or specific results. MIOM aims to monitor both ascending and descending pathways therefore giving immediate feedback information regarding any neurological deficits during the operation. Intraoperative sensory spinal and cortical evoked potentials, combined with monitoring of EMG and motor evoked potentials recorded from the spinal cord and muscles elicited by electrical motor cortex, spinal cord, cauda equina and nerve root stimulation, was evaluated and compared with post-operative clinical neurological changes. One thousand and seventeen consecutive patients underwent a total of 4,731 h of MIOM to evaluate any neural deficits that may have occurred during spine surgery. Of these, 935 were true negative cases, 8 were false negative cases, 66 were true positive cases and 8 were false positive cases, resulting in a sensitivity of 89% and a specificity of 99%. Based on the results of this study, MIOM is an effective method of monitoring the spinal cord functional integrity during spine surgery and therefore can lead to reduction of neurological deficit and consequently improve postoperative results.

  相似文献   
92.
High dose rate brachytherapy of localized prostate cancer   总被引:3,自引:0,他引:3  
OBJECTIVE: We evaluated the safety and efficacy of high dose rate (HDR) brachytherapy using Iridium-192 (Ir 192) and 3D conformal external beam radiotherapy in patients with localized prostate cancer. METHODS: A total of 444 patients with localized prostate cancer underwent combined radiotherapy with interstitial Ir 192 and 3D conformal external beam radiotherapy between December 1992 and March 2001. The 230 patients, treated between December 1992 and December 1997 were analyzed. All patients underwent laparoscopic pelvic lymph node dissection to exclude patients with lymphatic involvement. Ir 192 was delivered twice with a 1-week interval in HDR remote control technique. The interstitial dose from December 1992 to December 1993 was 10Gy, after December 1993 the dose was reduced to 9Gy per treatment session. The interstitial application was followed by external beam radiation of 45Gy for cT1-cT2 and 50.4Gy for cT3 tumor (40Gy from December 1992 to December 1993). Progression was defined as biochemical failure according to ASTRO criteria, e.g. three consecutive PSA rises following the PSA nadir. RESULTS: The median PSA value decreased from 12.8 to 0.93ng/ml 12 months after treatment. Median PSA value was 0.47 after 24 months, 0.30ng/ml after 36 months and 0.18ng/ml after 60 months. 68% of the biopsies were negative 24 months after therapy. Progression-free rate was 100% for cT1 tumors, 75% for cT2 and 60% for stage-cT3 on 5-year follow-up. Five-year overall survival was 93%, 5-year disease-specific survival was 98%. Initial PSA value <10ng/ml, low stage and low grade were significantly related to 5-year progression-free survival. CONCLUSIONS: Combined HDR brachytherapy with Ir 192 is an alternative treatment option especially for patients with cT3 prostate cancer. Initial PSA value, stage and grade, are important prognostic factors.  相似文献   
93.
Background To our best knowledge, Panton–Valentine leucocidin (PVL)-positive methicillin-sensitive Staphylococcus aureus (MSSA) has not been described yet as cause for severe pyomyositis. Case report We present a 23-year-old apparently healthy male patient without any typical predisposing findings who developed severe pyomyositis secondary to an operated pilonidal cyst. In the follow-up, the patient showed signs of immunocompromisation. The causative agent for purulent infection of multiple muscles was a MSSA strain harbouring PVL toxin. Results In the reported case, aggressive antibiotic and surgical treatment with additional application of immunoglobulins has lead to recovery from the disease without relapse. Conclusions PVL-positive S. aureus are associated with skin diseases, multiple abscesses and often complicated by severe sepsis and necrotising pneumonia. Under such circumstances, the mortality rate can reach up to 75%. In addition, the PVL toxin can cause immunocompromisation and might be therefore involved in the aetiology of pyomyositis. Aggressive antibiotic and surgical treatment with additional application of immunoglobulins is recommended for treatment.  相似文献   
94.
The impact of chronological age on longitudinal body growth from early childhood through adolescence using detailed anthropometric methods has not yet been studied in children with chronic kidney disease (CKD). We have evaluated growth failure by measuring four components of linear growth: body height (HT), sitting height (SHT), arm length (AL) and leg length (LL). Data were prospectively collected for up to 7 years on 190 boys (3–21 years old) with congenital or hereditary CKD (all had developed at least stage 2 CKD by the age of 10 years). Patients showed the most severe growth failure in early childhood, followed by an acceleration in growth in pre-puberty, a slowing-down of growth at puberty, as expected, and thereafter a late speeding-up of growth until early adulthood. This pattern was observed irrespective of the degree of CKD and different treatment modalities, such as conservative treatment, recombinant human growth hormone (rhGH) therapy or transplantation. LL showed the most dynamic growth changes of all the parameters evaluated and emerged as the best indicator of statural growth in children with CKD. A specific age-dependent pattern of physical growth was identified in pediatric male CKD patients. This growth pattern should be considered in the evaluation of individual growth and the assessment of treatment efficacy such as rhGH therapy.  相似文献   
95.
A lot of new implant devices for spine surgery are coming onto the market, in which vertebral screws play a fundamental role. The new screws developed for surgery of spine deformities have to be compared to established systems. A biomechanical in vitro study was designed to assess the bone–screw interface fixation strength of seven different screws used for correction of scoliosis in spine surgery. The objectives of the current study were twofold: (1) to evaluate the initial strength at the bone–screw interface of newly developed vertebral screws (Universal Spine System II) compared to established systems (product comparison) and (2) to evaluate the influence of screw design, screw diameter, screw length and bone mineral density on pullout strength. Fifty-six calf vertebral bodies were instrumented with seven different screws (USS II anterior 8.0 mm, USS II posterior 6.2 mm, KASS 6.25 mm, USS II anterior 6.2 mm, USS II posterior 5.2 mm, USS 6.0 mm, USS 5.0 mm). Bone mineral density (BMD) was determined by quantitative computed tomography (QCT). Failure in axial pullout was tested using a displacement-controlled universal test machine. USS II anterior 8.0 mm showed higher pullout strength than all other screws. The difference constituted a tendency (P = 0.108) when compared to USS II posterior 6.2 mm (+19%) and was significant in comparison to the other screws (+30 to +55%, P < 0.002). USS II posterior 6.2 mm showed significantly higher pullout strength than USS 5.0 mm (+30%, P = 0.014). The other screws did not differ significantly in pullout strength. Pullout strength correlated significantly with BMD (P = 0.0015) and vertebral body width/screw length (P < 0.001). The newly developed screws for spine surgery (USS II) show higher pullout strength when compared to established systems. Screw design had no significant influence on pullout force in vertebral body screws, but outer diameter of the screw, screw length and BMD are good predictors of pullout resistance.  相似文献   
96.
Abstract Objective: To define the diagnostic accuracy of clinical examination in patients with impaired consciousness or endotracheal intubation to detect pelvic ring fractures and to identify those with severe bleeding. Methods: Included in this prospective data collection with retrolective data analysis were a consecutive series of blunt trauma victims with either a Glasgow Coma Scale ≤ 13 or tracheal intubation. Clinical examination comprised testing for stability of the iliac wings. Results: From 784 subjects (injury severity score 23.3 ± 17.4) 93 patients (11.9%) were found to have a pelvic ring fracture. Clinical instability of the pelvic ring was found in 42 patients. There was only one false positive. Fifty-two fractures could not be identified by clinical examination, including nine fractures (17%) that required surgical fracture stabilization (sensitivity of clinical examination 44.1%). Seventeen fractures (18.3%) were associated with a blood loss larger than 20% of circulating blood volume. Sixteen of those were identified by clinical instability of the pelvic ring (sensitivity 94.1%, specificity 97.0%, positive predictive value 38.1%, negative predictive value 99.9%). Conclusions: Clinical examination for stability of the pelvis in this selected group of patients missed a significant number of pelvic ring fractures including fractures that require surgical stabilization. The finding of a clinically unstable identifies most of the patients with the pelvic ring fracture being a major source of bleeding. A stable pelvis makes pelvic ring fracture as being the source of bleeding quite unlikely.  相似文献   
97.
The major limitation in adult-to-adult living donor liver transplantation (LDLT) is an adequate graft size with special regard to the safety of the donor. Only 20% of the evaluated donors are suitable to donate the right liver, depending mainly on the critical remnant liver volume. We report 2 cases of adult-to-adult LDLT using dual grafts. In the first case we implanted a left lateral lobe together with a left lobe; in the second case we used a left lateral and a right lobe. Dual graft LDLT solves the problem of graft-size insufficiency and avoids critical right lobectomy in the donor. This procedure can be safely performed and opens up the possibility of LDLT to even more families in the Western world.  相似文献   
98.
BACKGROUND: The required erythropoiesis-stimulating agent (ESA) dose varies when correcting anaemia in chronic kidney disease (CKD) patients. This analysis was performed to identify the prevalence of and factors associated with ESA hyporesponsiveness. METHODS: This analysis was a post hoc evaluation of epoetin alfa dosage requirements in a subgroup of patients from the Effect of early Correction of Anemia on the Progression of CKD study. The patients in this subgroup were randomly assigned to the high haemoglobin target group (14-15 g/dl for men and 13-14 g/dl for women) and completed a 4-month haemoglobin stabilization phase with complete epoetin dosage data. The relationship of demographics, disease characteristics and laboratory measures with epoetin dosage were evaluated using Pearson's correlation, association measures and analysis of covariance (ANCOVA) models. RESULTS: Of the 93 patients evaluated in this subgroup analysis, 14 (15%) were hyporesponsive to epoetin (maximum dosage >100 IU/kg/week during stabilization). An ANCOVA analysis showed that 52% of the observed variability in epoetin dosage at completion of the stabilization phase could be accounted for by diabetes as the primary cause of kidney disease, angiotensin-converting enzyme (ACE) inhibitor/angiotensin receptor blocker (ARB) use, proteinuria, transferrin saturation, age, pre-treatment haemoglobin, geographical region, serum iron and body mass index (BMI). Unidentified patient characteristics accounted for an additional 16% of the dosage variance. CONCLUSIONS: Older age, higher BMI, anaemia, ACE inhibitor/ARB use and diabetes as the primary cause of kidney disease are associated with increased epoetin requirements when normalizing haemoglobin in anaemic CKD patients.  相似文献   
99.

Background

Severe brain trauma leads to an activation of the immune system. To this date, neither the exact perturbation of the specific immune reaction induced by the traumatic brain injury (TBI), nor the interactions leading to the infiltration of peripheral immune cells into the brain are fully understood.

Patients and methods

Serum was collected from 17 patients with TBI and a long bone fracture, 24 patients with an isolated long bone fracture and from healthy individuals. The effect of the serum on normal human monocytes and T-lymphocytes was tested in vitro by assessing proliferation and expression of surface markers, chemokine receptors and cytokines.

Results

Serum collected from patients with a TBI and a long bone fracture increased the expression of the chemokine receptor CCR4 in monocytes when compared to patients with an isolated long bone fracture. Extending this comparison to T-lymphocytes, the serum from TBI patients induced lower proliferation rates and decreased expression of the pro-inflammatory cytokine TNF-α, while simultaneously increasing the secretion of immune-modulatory cytokines (IL-4, IL-10 and TGF-β) (p < 0.05).

Conclusion

Patients with a TBI release currently unknown soluble factors into the circulating blood that up regulate expression of chemokine receptor CCR4 in peripheral blood monocytes whilst concurrently inducing expression of immunosuppressive cytokines by activated T-lymphocytes.  相似文献   
100.
Navigation technology is a widely available tool in spine surgery and has become a part of clinical routine in many centers. The issue of where and when navigation technology should be used is still an issue of debate. It is the aim of this study to give an overview on the current knowledge concerning the technical capabilities of image-guided approaches and to discuss possible future directions of research and implementation of this technique. Based on a Medline search total of 1,462 publications published until October 2008 were retrieved. The abstracts were scanned manually for relevance to the topics of navigated spine surgery in the cervical spine, the thoracic spine, the lumbar spine, as well as ventral spine surgery, radiation exposure, tumor surgery and cost-effectivity in navigated spine surgery. Papers not contributing to these subjects were deleted resulting in 276 papers that were included in the analysis. Image-guided approaches have been investigated and partially implemented into clinical routine in virtually any field of spine surgery. However, the data available is mostly limited to small clinical series, case reports or retrospective studies. Only two RCTs and one metaanalysis have been retrieved. Concerning the most popular application of image-guided approaches, pedicle screw insertion, the evidence of clinical benefit in the most critical areas, e.g. the thoracic spine, is still lacking. In many other areas of spine surgery, e.g. ventral spine surgery or tumor surgery, image-guided approaches are still in an experimental stage. The technical development of image-guided techniques has reached a high level as the accuracies that can be achieved technically meet the anatomical demands. However, there is evidence that the interaction between the surgeon (‘human factor’) and the navigation system is a source of inaccuracy. It is concluded that more effort needs to be spend to understand this interaction.  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