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   24847篇
  免费   1749篇
  国内免费   210篇
耳鼻咽喉   483篇
儿科学   398篇
妇产科学   455篇
基础医学   3518篇
口腔科学   576篇
临床医学   2156篇
内科学   5092篇
皮肤病学   707篇
神经病学   1596篇
特种医学   1354篇
外科学   3293篇
综合类   778篇
现状与发展   1篇
一般理论   14篇
预防医学   1162篇
眼科学   837篇
药学   2040篇
中国医学   253篇
肿瘤学   2093篇
  2023年   182篇
  2022年   265篇
  2021年   949篇
  2020年   512篇
  2019年   681篇
  2018年   823篇
  2017年   618篇
  2016年   810篇
  2015年   1076篇
  2014年   1272篇
  2013年   1354篇
  2012年   2145篇
  2011年   2054篇
  2010年   1167篇
  2009年   1042篇
  2008年   1478篇
  2007年   1407篇
  2006年   1335篇
  2005年   1261篇
  2004年   987篇
  2003年   829篇
  2002年   653篇
  2001年   536篇
  2000年   516篇
  1999年   421篇
  1998年   153篇
  1997年   125篇
  1996年   83篇
  1995年   89篇
  1994年   87篇
  1993年   71篇
  1992年   162篇
  1991年   173篇
  1990年   140篇
  1989年   133篇
  1988年   119篇
  1987年   140篇
  1986年   108篇
  1985年   99篇
  1984年   74篇
  1983年   71篇
  1982年   39篇
  1979年   62篇
  1977年   39篇
  1975年   38篇
  1974年   39篇
  1973年   36篇
  1972年   37篇
  1970年   35篇
  1969年   40篇
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
991.
Idiopathic hypertrophic spinal pachymeningitis (IHSP) is a chronic, progressive, inflammatory disorder characterized by marked fibrosis of the spinal dura mater with unknown etiology. According to the location of the lesion, it might induce neurologic deficits by compression of spinal cord and nerve root. A 58-year old female with a 3-year history of progressive weakness in both lower extremities was referred to our institute. Spinal computed tomography (CT) scan showed an osteolytic lesion involving base of the C6 spinous process with adjacent epidural mass. Magnetic resonance imaging (MRI) revealed an epidural mass involving dorsal aspect of cervical spinal canal from C5 to C7 level, with low signal intensity on T1 and T2 weighted images and non-enhancement on T1 weighted-enhanced images. We decided to undertake surgical exploration. At the operation field, there was yellow colored, thickened fibrous tissue over the dura mater. The lesion was removed totally, and decompression of spinal cord was achieved. Symptoms improved partially after the operation. Histopathologically, fibrotic pachymeninges with scanty inflammatory cells was revealed, which was compatible with diagnosis of idiopathic hypertrophic pachymeningitis. Six months after operation, motor power grade of both lower extremities was normal on physical examination. However, the patient still complained of mild weakness in the right lower extremity. Although the nature of IHSP is generally indolent, decompressive surgery should be considered for the patient with definite or progressive neurologic symptoms in order to prevent further deterioration. In addition, IHSP can present as an osteolytic lesion. Differential diagnosis with neoplastic disease, including giant cell tumor, is important.  相似文献   
992.

Objective

The purpose of this study was to evaluate the differences in sagittal spinopelvic alignment between lumbar degenerative spondylolisthesis (DSPL) and degenerative spinal stenosis (DSS).

Methods

Seventy patients with DSPL and 72 patients with DSS who were treated with lumbar interbody fusion surgery were included in this study. The following spinopelvic parameters were measured on whole spine lateral radiographs in a standing position : pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis angle (LL), L4-S1 segmental lumbar angle (SLL), thoracic kyphosis (TK), and sagittal vertical axis from the C7 plumb line (SVA). Two groups were subdivided by SVA value, respectively. Normal SVA subgroup and positive SVA subgroup were divided as SVA value (<50 mm and ≥50 mm). Spinopelvic parameters/PI ratios were assessed and compared between the groups.

Results

The PI of DSPL was significantly greater than that of DSS (p=0.000). The SVA of DSPL was significantly greater than that of DSS (p=0.001). In sub-group analysis between the positive (34.3%) and normal SVA (65.7%), there were significant differences in LL/PI and SLL/PI (p<0.05) in the DSPL group. In sub-group analysis between the positive (12.5%) and normal SVA (87.5%), there were significant differences in PT/PI, SS/PI, LL/PI and SLL/PI ratios (p<0.05) in the DSS group.

Conclusion

Patients with lumbar degenerative spondylolisthesis have the propensity for sagittal imbalance and higher pelvic incidence compared with those with degenerative spinal stenosis. Sagittal imbalance in patients with DSPL is significantly correlated with the loss of lumbar lordosis, especially loss of segmental lumbar lordosis.  相似文献   
993.
994.

Background

Glioblastoma (GBM) is the most life-threatening primary brain tumour. Especially in elderly patients, a poorer outcome is noticeable. Until now, the effectiveness of the conventional active treatment has been controversial. The purpose of this study is to find the optimal treatment for elderly patients with newly diagnosed GBM.

Method

The authors retrospectively reviewed 301 patients who were diagnosed with GBM at a single centre from January 2006 to December 2010. All patients were divided into younger and elderly groups based on the cut-off age of 65 years, and the treatment outcome was analysed.

Results

Of 301 patients, 67 (23.3 %) patients were 65 years old or older, and 234 (77.7 %) patients were younger than 65 years. In the elderly group, 49 patients received surgical resection and 18 patients received biopsy. Forty-seven patients (70.1 %) underwent concomitant chemoradiotherapy (CCRT) and 38 patients (56.7 %) underwent adjuvant temozolomide (TMZ) chemotherapy. The median overall survival (OS) of elderly patients was 12.0 months and the progression-free survival (PFS) was 8.5 months. The median OS of elderly patients who underwent CCRT and adjuvant TMZ chemotherapy increased to 16.2 months. On the multivariate analysis, tumour infiltration (p?=?0.005), and resection (p?=?0.001) were significant independent prognostic factors in elderly patients. The grade 3 or 4 complication rate was not statistically different between the younger group (n?=?22, 9.4 %) and the elderly group (n?=?8, 12 %).

Conclusion

Elderly patients diagnosed with GBM had a survival benefit and a low complication rate with the conventional treatment. Therefore, elderly patients should be encouraged to receive the conventional active treatment.  相似文献   
995.

Background

Although the majority of patients with minimal acute subdural hematomas (aSDHs) can be managed conservatively, some require delayed aSDH evacuation due to hematoma enlargement. This study was designed to determine the risk factors associated with delayed hematoma enlargement leading to surgery in patients with aSDHs who did not initially require surgical intervention.

Methods

From 2002 to 2012, 98 patients were treated for nonoperative aSDHs following mild head injury (Glasgow Coma Scale scores of 13–15). The outcome variables were radiographic evidence of SDH enlargement on serially obtained computed tomography (CT) images and later surgical evacuation. Univariate and multivariate analyses were applied to both the demographic and initial radiographic features to identify risk factors for SDH progression and surgery.

Results

Overall, 64 patients (65 %) revealed minimal SDH or spontaneous hematoma resolution (conservative group) with conservative management at their last follow-up CT scan. The remaining 34 patients (35 %) received delayed hematoma evacuation (delayed surgery group) a median of 17 days after the head trauma. There were no significant differences between the two groups for baseline characteristics, including age, injury type, degree of brain atrophy, prior history of antithrombotic drugs, and coagulopathy. The presence of cerebral contusions and subarachnoid hemorrhages was more common in the conservative group (p?=?0.003 and p?=?0.003, respectively). On multivariate analysis, hematoma volume (p?=?0.01, odds ratio [OR]?=?1.094, 95 % confidence interval [CI]?=?1.021–1.173) and degree of midline shift (p?=?0.01, OR?=?1.433, 95 % CI?=?1.088–1.888) on the initial CT scan were independently associated with delayed hematoma evacuation.

Conclusions

A critical proportion of patients with minimal aSDHs occurring after mild head injury can progress over several weeks and require hematoma evacuation. Especially patients with a large initial SDH volume and accompanying midline shift require careful monitoring of hematoma progression.  相似文献   
996.

Aim

The aim of the present study was to determine (1) whether successful intraoperative electromyography monitoring for lateral spread response (LSR) is possible with partial neuromuscular blockade (NMB) in subjects undergoing microvascular decompression (MVD) for hemifacial spasm and (2) the adequate level of NMB to achieve that goal.

Material and methods

A total of 61 patients in whom LSR was monitored during MVD were enrolled in the study. Patients were randomly allocated to two groups: group TOF in which the NMB target was maintenance of two train-of-four (TOF) counts and group T1 in which the NMB target was maintenance of a T1/Tc ratio of 50?% (T1: first twitch height of TOF and Tc: control twitch height). The adductor pollicis brevis muscle was used to monitor TOF responses. The frequency of successful LSR monitoring, defined as successful baseline establishment and maintenance of LSR until surgical decompression, was compared between the two groups.

Results

Of the 61 patients 2 were excluded from the study so that 30 patients in group TOF and 29 patients in group T1 were analyzed. The success rate of LSR monitoring was clinically acceptable and significantly higher in group T1 than in group TOF, i.e. n?=?15 (50.0?%) in group TOF versus n?=?24 (82.8?%) in group T1 (P?=?0.008), corresponding to a 32.8?% higher success rate in group T1 than group TOF (95?% CI: 13.9–51.7?%). Mean vecuronium infusion dose was smaller and mean TOF count was higher in group T1 than group TOF with a TOF count =?2 (1) in group TOF versus 3 (1) in group T1 (P?=?0.003). Mean sevoflurane and remifentanil infusion doses were not different between groups. There was no incidence of spontaneous movement during microscopy in either group.

Conclusion

Maintenance of partial NMB with a target T1/Tc ratio of 50?% resulted in a clinically acceptable success rate of LSR monitoring and surgical condition during MVD. Maintenance of partial NMB with a target T1/Tc ratio of 50?% rather than TOF count of two during LSR monitoring for MVD can therefore be recommended.  相似文献   
997.
998.
999.
Impaired angiogenesis in ischemic tissue is a hallmark of diabetes. Thioredoxin-interacting protein (TXNIP) is an exquisitely glucose-sensitive gene that is overexpressed in diabetes. As TXNIP modulates the activity of the key angiogenic cytokine vascular endothelial growth factor (VEGF), we hypothesized that hyperglycemia-induced dysregulation of TXNIP may play a role in the pathogenesis of impaired angiogenesis in diabetes. In the current study, we report that high glucose–mediated overexpression of TXNIP induces a widespread impairment in endothelial cell (EC) function and survival by reducing VEGF production and sensitivity to VEGF action, findings that are rescued by silencing TXNIP with small interfering RNA. High glucose–induced EC dysfunction was recapitulated in normal glucose conditions by overexpressing either TXNIP or a TXNIP C247S mutant unable to bind thioredoxin, suggesting that TXNIP effects are largely independent of thioredoxin activity. In streptozotocin-induced diabetic mice, TXNIP knockdown to nondiabetic levels rescued diabetes-related impairment of angiogenesis, arteriogenesis, blood flow, and functional recovery in an ischemic hindlimb. These findings were associated with in vivo restoration of VEGF production to nondiabetic levels. These data implicate a critical role for TXNIP in diabetes-related impairment of ischemia-mediated angiogenesis and identify TXNIP as a potential therapeutic target for the vascular complications of diabetes.  相似文献   
1000.

Purpose

The purpose of this study was to characterize the growth rate of sacrococcygeal teratomas (SCTs) and determine its relationship to adverse outcomes.

Methods

A retrospective review of all pathology-confirmed isolated SCT patients evaluated with at least two documented ultrasounds and followed through hospital discharge between 2005 and 2012 was conducted. SCT growth rate was calculated as the difference between tumor volumes on a late- and early-gestation ultrasound divided by the difference in time. Outcomes were death, high-output cardiac failure (HOCF), hydrops, and preterm delivery. Student's t-test, receiver operator characteristics, Fisher's Exact test, and Pearson's correlation were performed.

Results

Of the 28 study subjects, there were 3 in utero demises and 2 neonatal deaths. Significantly faster SCT growth rates were seen in all adverse outcomes, including death (p < 0.0001), HOCF (p = 0.005), and preterm delivery (p = 0.009). There was a significant association with adverse outcomes at > 61 cm3/week (AUC = 0.87, p = 0.001, LR = 4.52). Furthermore, there was an even greater association with death at > 165 cm3/week (AUC = 0.93, p = 0.003, LR = 18.42). Growth rate was directly correlated with the percent of solid tumor (r = 0.60, p = 0.0008).

Conclusion

Faster SCT growth is associated with adverse outcomes. SCT growth rate determined by ultrasound is an effective prognostic indicator for adverse outcomes and easily applied to patient management.  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