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   38498篇
  免费   1733篇
  国内免费   302篇
耳鼻咽喉   295篇
儿科学   724篇
妇产科学   429篇
基础医学   5123篇
口腔科学   1059篇
临床医学   2231篇
内科学   9444篇
皮肤病学   955篇
神经病学   2785篇
特种医学   1311篇
外科学   6834篇
综合类   160篇
一般理论   1篇
预防医学   1045篇
眼科学   800篇
药学   2260篇
中国医学   128篇
肿瘤学   4949篇
  2023年   211篇
  2022年   557篇
  2021年   908篇
  2020年   462篇
  2019年   668篇
  2018年   898篇
  2017年   679篇
  2016年   801篇
  2015年   835篇
  2014年   1117篇
  2013年   1431篇
  2012年   2321篇
  2011年   2692篇
  2010年   1537篇
  2009年   1259篇
  2008年   2320篇
  2007年   2546篇
  2006年   2390篇
  2005年   2550篇
  2004年   2486篇
  2003年   2477篇
  2002年   2479篇
  2001年   478篇
  2000年   407篇
  1999年   532篇
  1998年   598篇
  1997年   477篇
  1996年   448篇
  1995年   398篇
  1994年   350篇
  1993年   318篇
  1992年   307篇
  1991年   267篇
  1990年   269篇
  1989年   240篇
  1988年   198篇
  1987年   181篇
  1986年   175篇
  1985年   145篇
  1984年   148篇
  1983年   117篇
  1982年   95篇
  1981年   98篇
  1980年   93篇
  1979年   84篇
  1978年   53篇
  1977年   42篇
  1976年   34篇
  1975年   42篇
  1973年   36篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.

Background

Preoperative traction for hip fractures is of no benefit in semi-urgent surgery. However, its efficacy has not been assessed in cases in which emergency surgery was not possible. We evaluated the efficacy of preoperative skin traction for hip fractures in a level II trauma center in Japan where many patients undergo delayed surgery.

Methods

We undertook a randomized controlled trial. Eighty-one patients were randomized to be treated with skin traction (41 patients), or bed rest (40 patients). Preoperative pain was assessed by use of a visual analogue scale and the number of analgesics required. Fracture reduction was measured on the basis of leg-length and neck–shaft angle discrepancies on the radiograph on admission, a day before surgery, and after surgery.

Results

The mean time from admission to surgery was 7.5 days. Pain decreased markedly on the day after admission in both the traction and no-traction groups. No significant difference was found during the preoperative waiting period between the groups in either pain score or number of analgesics taken. No significant difference was found in radiographic data either before or after surgery, and satisfactory reduction was achieved after surgery irrespective of the use of skin traction.

Conclusions

In our single-institution prospective randomized controlled trial, preoperative skin traction for patients with hip fracture had no effect on pain relief before surgery or reduction of fracture displacement during surgery, irrespective of preoperative waiting time.  相似文献   
992.
993.
Bone marrow‐derived stromal cells (BMSCs) contain mesenchymal stem cells that are capable of forming various mesenchymal tissues. We hypothesized that BMSCs and β‐tricalcium phosphate (β‐TCP) composites would promote the remodeling of large‐sized autologous devitalized bone grafts; therefore, the aim of this study was to evaluate the effects of the composites on the remodeling of autologous devitalized bone grafts. Autologous BMSCs cultured in culture medium containing dexamethasone (10?7 M) were loaded into porous β‐TCP granules under low‐pressure. Theses BMSC/TCP composites were put into the bone marrow cavity of autologous heat‐treated bone (femoral diaphysis, 65‐mm long, 100°C, 30 min) and put back to the harvest site. In the contralateral side, β‐TCP without BMSC were used in the same manner as the opposite side as the control. Treatment with the BMSC/TCP composites resulted in a significant increase in thickness, bone mineral density, and matured bone volume of the cortical bone at the center of the graft compared to the control. Histological analysis showed matured regenerated bone in the BMSC loaded group. These results indicate that BMSC/TCP composites facilitated bone regeneration and maturation at the graft site of large‐sized devitalized bone. This method could potentially be applied for clinical use in the reconstruction of large bone defects such as those associated with bone tumors. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1308–1316, 2013
  相似文献   
994.
We conducted the prospective randomized controlled trial to test that continuous femoral nerve block (CFNB) improves attainment of 120° knee flexion compared to continuous epidural analgesia (CEA). Sixty-six patients scheduled for unilateral total knee arthroplasty were randomized into two groups; infusion of ropivacaine 0.15% into CEA or CFNB to third postoperative days. We studied the time required to attain 120° knee flexion, variations in thigh and calf circumferences around the treated knee, pain scores, rehabilitation milestones, the need for adjuvant analgesics, and side effects. CFNB patients attained earlier knee flexion to 120°, lower variations in thigh and calf circumferences, less pain during rehabilitation, and less need for adjuvant analgesics. CFNB is a better pain management strategy that accelerates knee flexion rehabilitation.  相似文献   
995.
996.

Purpose

Curved peri-acetabular osteotomy (CPO) produces excellent clinical results, but the surgical procedure is technically demanding, and severe complications related to the osteotomy have been reported. To provide a safe, accurate surgical procedure, we have developed a novel method for setting the cutting line and direction. We have designed and made a custom cutting guide for individual patients. The purpose of the study was to evaluate the efficacy of this new method and cutting guide.

Methods

The cutting line was designed on a full-scale three-dimensional plaster model made from computed tomography (CT) data for each case. The surface of each plaster model was colour-coded according to the distance from the centre of the femoral head. A custom cutting guide was designed based on this cutting line on the workstation. A titanium custom cutting guide was fabricated using rapid prototyping technology. The cutting guide directed the cutting direction of the osteotome. We evaluated the outcomes for seven consecutive hips in seven patients who underwent CPO using the system between April and December 2011. All peri-operative complications were recorded. The accuracy of the cutting line was evaluated using CT data obtained two weeks after the operation.

Results

There were no major complications related to the osteotomy such as posterior column fracture or intra-articular osteotomy. The actual cutting line corresponded almost exactly to the planned cutting line in all cases.

Conclusions

The colour-coded plaster model and the custom cutting guide were effective for avoiding severe complications associated with a CPO.  相似文献   
997.
The diagnosis and treatment of pituitary macroadenomas with entire hematoma fluid accumulation are problematic. Such lesions are often difficult to completely resect, and recurrence is not uncommon. We present five cases of pituitary macroadenomas entirely composed of hematoma fluid and investigated their histopathology to clarify the mechanism of the hematoma fluid accumulation. Five patients with pituitary adenoma and significant intra-tumor hematoma underwent transsphenoidal resection and were retrospectively reviewed for their clinical status, findings on magnetic resonance imaging (MRI), intraoperative findings, and histopathology. The specific surgical techniques used to address these cases were also reviewed. All patients were diagnosed with nonfunctioning pituitary adenomas by histopathological examination. MRI showed all tumors extended to the cavernous sinus. Histopathology showed tumor tissues were located between the thick granulation tissue and the pseudocapsule of the tumor. The thick granulation tissues were composed of collagenous layers, neovascular vessels, and necrotic red blood cells, indicating repeat hemorrhage from the granulation tissues. The boundary between adenoma and normal pituitary gland was identified during surgical removal in four patients and was not identified in the other patient who showed a recurrence 2 years later. Clinical and histopathological findings indicate hematoma fluid accumulation in the present cases is caused by repeat hemorrhage from the reactive granulation tissues and can be regarded as a chronic encapsulated expanding hematoma. In these cases, the boundary between adenoma and normal pituitary gland should be identified before puncturing the hematoma fluid to minimize the risk of tumor recurrence.  相似文献   
998.
Cytosolic isocitrate dehydrogenase 1 (IDH1) with an R132H mutation in brain tumors loses its enzymatic activity for catalyzing isocitrate to α-ketoglutarate (α-KG) and acquires new activity whereby it converts α-KG to 2-hydroxyglutarate. The IDH1 mutation induces down-regulation of tricarboxylic acid cycle intermediates and up-regulation of lipid metabolism. Sterol regulatory element-binding proteins (SREBPs) regulate not only the synthesis of cholesterol and fatty acids but also acyclin-dependent kinase inhibitor p21 that halts the cell cycle at G1. Here we show that SREBPs were up-regulated in U87 human glioblastoma cells transfected with an IDH1R132H-expression plasmid. Small interfering ribonucleic acid (siRNA) for SREBP1 specifically decreased p21 messenger RNA (mRNA) levels independent of the p53 pathway. In IDH1R132H-expressing U87 cells, phosphorylation of Retinoblastoma (Rb) protein also decreased. We propose that metabolic changes induced by the IDH1 mutation enhance p21 expression via SREBP1 and inhibit phosphorylation of Rb, which slows progressionof the cell cycle and may be associated with non-aggressive features of gliomas with an IDH1 mutation.  相似文献   
999.
1000.
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