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   186篇
  免费   121篇
  国内免费   2篇
  2024年   1篇
  2023年   16篇
  2022年   17篇
  2021年   29篇
  2020年   25篇
  2019年   22篇
  2018年   23篇
  2017年   24篇
  2016年   14篇
  2015年   21篇
  2014年   27篇
  2013年   25篇
  2012年   8篇
  2011年   7篇
  2010年   5篇
  2009年   5篇
  2008年   6篇
  2007年   2篇
  2006年   4篇
  2005年   8篇
  2004年   2篇
  2003年   4篇
  2002年   3篇
  2001年   1篇
  2000年   2篇
  1998年   2篇
  1996年   1篇
  1991年   1篇
  1985年   2篇
  1983年   1篇
  1971年   1篇
排序方式: 共有309条查询结果,搜索用时 15 毫秒
31.
摘要 目的:研究不同体质量指数(BMI)对腹腔镜结直肠癌切除术患者临床疗效和远期预后的影响。方法:将从2014年1月~2016年1月于我院接受腹腔镜结直肠癌切除术治疗的110例患者纳入研究。将所有受试者根据BMI的差异分作正常组(18.6 kg/m2≦BMI<23.0 kg/m2)35例、超重组(23.0 kg/m2≦BMI<25.0 kg/m2)53例、肥胖组(BMI≧25.0 kg/m2)22例。分析三组患者各项基线资料,临床疗效,术后并发症发生情况,远期预后等方面的差异。结果:三组患者各项基线资料比较差异均不明显(均P>0.05)。肥胖组手术时长为(268.01±36.14)min,均明显高于正常组、超重组的(211.73±30.56)min、(224.12±34.87)min(均P<0.05);三组术中失血量、肛门排气时间以及住院康复时间对比均不明显(均P>0.05)。三组患者术后肺部感染、下肢静脉血栓、切口感染以及吻合口出血发生率对比均不明显(均P>0.05)。正常组5年生存率为45.71%(16/35),超重组5年生存率为47.17%(25/53),肥胖组5年生存率为45.45%(10/22),三组比较差异无统计学意义(均P>0.05)。结论:不同BMI对腹腔镜结直肠癌切除术患者的手术时长具有一定影响,但和远期预后无关,值得临床重点关注。  相似文献   
32.
目的:探讨肝癌乙型肝炎病毒(HBV)感染患者根治性切除术后采用恩替卡韦抗病毒治疗的临床疗效及安全性。方法:收集2015年1月-2017年8月在我院行根治性切除术的肝癌HBV感染患者279例为研究对象,以血清HBV-DNA载量10~5 copies/ml为界限,分为高病毒复制组128例,低病毒复制组151例,按照随机数字表法将高病毒复制组分为高-治疗组64例、高-对照组64例,将低病毒复制组分为低-治疗组76例、低-对照组75例。高-治疗组和低-治疗组术后给予恩替卡韦0.5 mg/d,高-对照组和低-对照组未行抗病毒治疗。比较手术前、术后7 d各组的血清HBV-DNA水平,血清白蛋白(ALB)、谷丙转氨酶(ALT)、前白蛋白(PA),以及术后并发症的发生情况。结果:高-治疗组、高-对照组、低-治疗组、低-对照组术后血清ALB、PA均较治疗前降低,血清ALT均较治疗前升高,且高-治疗组或低-治疗组术后血清ALB、PA均高于高-对照组或低-对照组,血清ALT水平均低于高-对照组或低-对照组,差异均有统计学意义(P0.05);高-治疗组或低-治疗组术后血清HBV-DNA水平均低于治疗前,且均低于同期高-对照组或低-对照组,差异均有统计学意义(P0.05)。高-治疗组与高-对照组、低-治疗组与低-对照组患者术后并发症发生率均无统计学差异(P0.05)。结论:恩替卡韦能显著改善肝癌HBV感染患者术后的血清HBV-DNA载量水平和肝功能,安全性高,值得临床推广。  相似文献   
33.
目的:探讨手辅助腹腔镜手术(hand-assisted laparoscopic surgery,HALS)与全腹腔镜手术(laparoscopic surgery,LAP)用于直肠癌根治术患者的临床疗效及其对血清炎性因子水平的影响。方法:选取2013年3月~2018年3月在我院行直肠癌根治术的患者61例进行回顾性分析,按照手术方式不同分为手辅助腹腔镜手术组(HALS组)和全腹腔镜手术组(LAP组)。比较两组患者的手术相关指标、术后恢复指标和治疗前后血清炎性因子水平的变化。结果:HALS组的手术时间、术中出血量和副损伤显著低于LAP组(P0.05),两组中转开腹率相比无统计学差异(P0.05);两组患者术后肠功能恢复时间、进食时间、下床时间和住院时间比较均无显著性差异(P0.05);两组患者术后1 h和术后1 d血清白细胞介素-10(interleukin-10, IL-10)、C-反应蛋白(C reactive protein,CRP)和α肿瘤坏死因子(Tumor Necrosis Factor-α,TNF-α)水平均较术前显著升高,且HALS组显著低于LAP组(P0.05),术后1 w血清IL-10、CRP和TNF-α水平与术前相比无统计学差异(P0.05)。结论:HALS直肠癌根治术对患者的手术创伤小,炎性反应轻,且不影响患者的预后,利于患者的康复。  相似文献   
34.
目的:探讨宫腔镜下采取子宫内膜电切术联合刮宫术对于治疗多发性子宫内膜息肉(EMP)患者的临床效果。方法:选取2012年6月至2014年3月在我院确诊为EMP的患者100例,随机平均分为两组,研究组采取宫腔镜下子宫内膜电切术联合刮宫术治疗,对照组单纯采取宫腔镜下子宫内膜电切术治疗。观察两组患者术中出血量、手术时间、一年内子宫息肉的复发率及子宫异常出血的发病率。结果:两组术中出血量、手术时间及子宫息肉复发率比较差异无统计学意义(P0.05)。研究组子宫异常出血发病率低于对照组,差异有统计学意义(P0.05)。结论:宫腔镜下电切术联合刮宫术对于治疗EMP的效果更佳,可降低子宫异常出血发病率,安全有效,值得临床进一步推广。  相似文献   
35.
The mandibular condyle is considered a good model for developing cancellous bone because of its rapid growth and high rate of remodeling. The aim of the present study was to analyze the simultaneous changes in microarchitecture and mineralization of cancellous bone during development in a three-dimensional fashion. Eight mandibular condyles of pigs aged 8 weeks prepartum to 108 weeks postpartum were scanned using microCT with an isotropic spatial resolution of 10 microm. The number of trabeculae decreased during development, whereas both the trabecular thickness and the distance between the trabeculae increased. The bone surface to volume ratio decreased during development, possibly limiting the amount of (re)modeling. Both the mean degree of mineralization and intratrabecular differences in mineralization between the surfaces and cores of trabecular elements increased during development. The trabecular surfaces were more highly mineralized in the older condyles compared to the younger ones. Together with the observed decrease in the relative size of trabecular surface, this finding suggests a decrease in (re)modeling activity during development. In accordance with the general growth and development of the pig, it was concluded that most developmental changes in cancellous bone occur until the age of 40 weeks postpartum.  相似文献   
36.
In the context of osteoporosis, evaluation of bone fracture risk and improved design of epiphyseal bone implants rely on accurate knowledge of the mechanical properties of trabecular bone. A multi-axial loading chamber was designed, built and applied to explore the compressive multi-axial yield and strength properties of human trabecular bone from different anatomical locations. A thorough experimental protocol was elaborated for extraction of cylindrical bone samples, assessment of their morphology by micro-computed tomography and application of different mechanical tests: torsion, uni-axial traction, uni-axial compression and multi-axial compression. A total of 128 bone samples were processed through the protocol and subjected to one of the mechanical tests up to yield and failure. The elastic data were analyzed using a tensorial fabric–elasticity relationship, while the yield and strength data were analyzed with fabric-based, conewise generalized Hill criteria. For each loading mode and more importantly for the combined results, strong relationships were demonstrated between volume fraction, fabric and the elastic, yield and strength properties of human trabecular bone. Despite the reviewed limitations, the obtained results will help improve the simulation of the damage behavior of human bones and bone-implant systems using the finite element method.  相似文献   
37.
Site-1 protease (S1P) is a proprotein convertase with essential functions in lipid homeostasis and unfolded protein response pathways. We previously studied a mouse model of cartilage-specific knock-out of S1P in chondroprogenitor cells. These mice exhibited a defective cartilage matrix devoid of type II collagen protein (Col II) and displayed chondrodysplasia with no endochondral bone formation even though the molecular program for endochondral bone development appeared intact. To gain insights into S1P function, we generated and studied a mouse model in which S1P is ablated in postnatal chondrocytes. Postnatal ablation of S1P results in chondrodysplasia. However, unlike early embryonic ablations, the growth plates of these mice exhibit a lack of Ihh, PTHrP-R, and Col10 expression indicating a loss of chondrocyte hypertrophic differentiation and thus disruption of the molecular program required for endochondral bone development. S1P ablation results in rapid growth plate disruption due to intracellular Col II entrapment concomitant with loss of chondrocyte hypertrophy suggesting that these two processes are related. Entrapment of Col II in the chondrocytes of the prospective secondary ossification center precludes its development. Trabecular bone formation is dramatically diminished in the primary spongiosa and is eventually lost. The primary growth plate is eradicated by apoptosis but is gradually replaced by a fully functional new growth plate from progenitor stem cells capable of supporting new bone growth. Our study thus demonstrates that S1P has fundamental roles in the preservation of postnatal growth plate through chondrocyte differentiation and Col II deposition and functions to couple growth plate maturation to trabecular bone development in growing mice.  相似文献   
38.
Several studies have shown the presence of fibroblast-like cells in the stromal fraction of different tissues with a high proliferative and differentiation potential. Platelet alpha granules contain growth factors released into the environment during activation. The effects of different supplements for culture medium (human serum, bovine serum and platelet lysate) on cultured human fibroblast-like cells from bone marrow, adipose tissue, trabecular bone and dental pulp have been compared. Expression of typical stromal and hematopoietic markers was analyzed and proliferative rates were determined. Flow cytofluorometry showed a homogenous pattern in serial-passaged cells, with a high level of stromal cell-associated markers (CD13, CD90, CD105). The presence of platelet lysate in culture media increased the number of cell generations obtained regardless of cell source. This effect was serum-dependent. Cell-based therapies can benefit by the use of products from human origin for “ex vivo” expansion of multipotent cells.  相似文献   
39.
The ability to predict trabecular failure using microstructure-based computational models would greatly facilitate study of trabecular structure–function relations, multiaxial strength, and tissue remodeling. We hypothesized that high-resolution finite element models of trabecular bone that include cortical-like strength asymmetry at the tissue level, could predict apparent level failure of trabecular bone for multiple loading modes. A bilinear constitutive model with asymmetric tissue yield strains in tension and compression was applied to simulate failure in high-resolution finite element models of seven bovine tibial specimens. Tissue modulus was reduced by 95% when tissue principal strains exceeded the tissue yield strains. Linear models were first calibrated for effective tissue modulus against specimen-specific experimental measures of apparent modulus, producing effective tissue moduli of (mean±S.D.) 18.7±3.4 GPa. Next, a parameter study was performed on a single specimen to estimate the tissue level tensile and compressive yield strains. These values, 0.60% strain in tension and 1.01% strain in compression, were then used in non-linear analyses of all seven specimens to predict failure for apparent tensile, compressive, and shear loading. When compared to apparent yield properties previously measured for the same type of bone, the model predictions of both the stresses and strains at failure were not statistically different for any loading case (p>0.15). Use of symmetric tissue strengths could not match the experimental data. These findings establish that, once effective tissue modulus is calibrated and uniform but asymmetric tissue failure strains are used, the resulting models can capture the apparent strength behavior to an outstanding level of accuracy. As such, these computational models have reached a level of fidelity that qualifies them as surrogates for destructive mechanical testing of real specimens.  相似文献   
40.
Nucleotide modifications to microRNAs or their precursors can influence their processing and/or activity. A challenge to their analysis is the lack of independent references for the termini generated by primary processing; typically, these are empirically assigned as the most abundant mapped reads. Mirtrons offer such an independent measure since these microRNA hairpins are defined by splicing. Consequently, mirtron-derived reads that deviate from splice sites reflect modification following primary processing. Analysis in Drosophila revealed multiple modification patterns, including select alterations of 5' termini, many 3' resection events, and unexpectedly abundant 3' untemplated monouridylation. Resections occur on mature AGO1-loaded species, whereas uridylation occurs on pre-miRNAs but is compatible with dicing and AGO1 loading. Strikingly, we found many mirtrons whose modified reads are more abundant than those produced by primary processing. In some cases, these abundant modified reads matched the genome owing to fortuitous uridines in downstream flanking exons, thus highlighting the value of an independent reference for the primary-processed sequence. We could further extend the principle of abundant and preferred uridylation of mirtrons, relative to canonical pre-miRNAs, to Caenorhabditis elegans, mouse, and human. Finally, we found that 3' resection occurs broadly across AGO1-loaded canonical miRNA and star species. Altogether, these findings substantially broaden the complexity of terminal modification pathways acting upon small regulatory RNAs.  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