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   236篇
  免费   30篇
  2024年   1篇
  2023年   8篇
  2022年   9篇
  2021年   11篇
  2020年   9篇
  2019年   9篇
  2018年   15篇
  2017年   1篇
  2016年   7篇
  2015年   11篇
  2014年   17篇
  2013年   29篇
  2012年   15篇
  2011年   10篇
  2010年   7篇
  2009年   5篇
  2008年   14篇
  2007年   12篇
  2006年   8篇
  2005年   4篇
  2004年   1篇
  2003年   9篇
  2002年   3篇
  2001年   5篇
  2000年   5篇
  1999年   2篇
  1998年   3篇
  1997年   1篇
  1996年   2篇
  1995年   4篇
  1994年   1篇
  1992年   2篇
  1991年   2篇
  1989年   2篇
  1988年   1篇
  1986年   1篇
  1984年   3篇
  1983年   2篇
  1982年   4篇
  1980年   1篇
  1978年   2篇
  1977年   3篇
  1976年   2篇
  1975年   1篇
  1974年   2篇
排序方式: 共有266条查询结果,搜索用时 203 毫秒
31.
A novel technique is reported for softening plant tissues while retaining their shape by impregnating them with macerating enzymes under reduced pressure after defrosting the frozen plants. Samples were removed immediately from the enzyme solution after the freeze-infusion treatment, and the hardness was measured. Six enzymes and three enzymes were respectively chosen from 18 commercial enzymes for softening burdock roots and bamboo shoots. The tissue degradation due to impregnation of the tissues with the enzymes and the reaction time were investigated. Burdock roots and bamboo shoots were progressively softened during the reaction: the hardness reached 1.0×104 N/m2 or less. The water-soluble dietary fiber contents increased as a result of the freeze-infusion treatment. This softening technique, which retained the food shape, could enhance the production of food products for elderly persons and those under nursing care. Foods produced by this method can replace current minced and liquid dietary components.  相似文献   
32.
目的:探讨定坤丹联合益母草冲剂治疗孕妇流产后月经失调的临床效果。方法:选取2016年1月-2016年12月我院接受药物流产终止妊娠的妇女120例为研究对象,根据数字随机表法将其随机分为研究组和对照组,每组60例。研究组在妊娠囊排出宫腔后开始服益母草冲剂,1包/次,3次/日,服用2周后加服定坤丹,1丸/次,2次/日,持续服用到月经恢复正常。对照组在同一时间段期间服用益母草冲剂。对比两组患者腹痛消失时间和月经恢复正常时间、恢复正常月经后月经周期、月经量以及治疗有效率。结果:对照组和研究组腹痛消失时间分别为7.62±1.33 d、3.17±0.76 d,月经恢复正常时间分别为69.62±8.45 d、43.21±6.65 d,研究组均显著短于对照组(P0.05)。患者月经恢复后,对照组中有42例正常,研究组有54例正常,研究组月经周期时间正常率显著高于对照组(P0.05)。对照组中月经量有45例正常,研究组中月经量有54例正常,两组月经量比较,研究组月经量正常率显著高于对照组(P0.05)。对照组中痊愈39例,研究组中痊愈51例,研究组治疗有效率显著高于对照组(P0.05)。结论:定坤丹联合益母草冲剂治疗孕妇流产后月经失调临床疗效明显优于单用益母草冲剂治疗。  相似文献   
33.
BackgroundAs overall cancer survival continues to improve, the incidence of metastatic lesions to the bone continues to increase. The subsequent skeletal related events that can occur with osseous metastasis can be debilitating. Complete and impending pathologic femur fractures are common with patients often requiring operative fixation. However, the efficacy of an intramedullary nail construct, on providing stability, continue to be debated. Therefore, the purpose of this study was to utilize a synthetic femur model to determine 1) how proximal femur defect size and cortical breach impact femur load to failure (strength) and stiffness, and 2) and how the utilization of an IMN, in a prophylactic fashion, subsequently alters the overall strength and stiffness of the proximal femur.MethodsA total of 21 synthetic femur models were divided into four groups: 1) intact (no defect), 2) 2 cm defect, 3) 2.5 cm defect, and 4) 4 cm defect. An IMN was inserted in half of the femur specimens that had a defect present. This procedure was performed using standard antegrade technique. Specimens were mechanically tested in offset torsion. Force-displacement curves were utilized to determine each constructs load to failure and overall torsional stiffness. The ultimate load to failure and construct stiffness of the synthetic femurs with defects were compared to the intact synthetic femur, while the femurs with the placement of the IMN were directly compared to the synthetic femurs with matching defect size.ResultsThe size of the defect invertedly correlated with the load the failure and overall stiffness. There was no difference in load to failure or overall stiffness when comparing intact models with no defect and the 2 cm defect group (p=0.98, p=0.43). The 2.5 cm, and 4.5 cm defect groups demonstrated significant difference in both load to failure and overall stiffness when compared to intact models with results demonstrating 1313 N (95% CI: 874-1752 N; p<0.001) and 104 N/mm (95% CI: 98-110 N/mm; p=0.03) in the 2.5 cm defect models, and 512 N (95% CI: 390-634 N, p<0.001) and 21 N/mm (95% CI: 9-33 N/mm, p<0.001) in the models with a 4 cm defect. Compared to the groups with defects, the placement an IMN increased overall stiffness in the 2.5 cm defect group (125 N/mm; 95% CI:114-136 N/mm; p=0.003), but not load to failure (p=0.91). In the 4 cm defect group, there was a significant increase in load to failure (1067 N; 95% CI: 835-1300 N; p=0.002) and overall stiffness (57 N/mm; 95% CI:46-69 N/mm; p=0.001).ConclusionProphylactic IMN fixation significantly improved failure load and overall stiffness in the group with the largest cortical defects, but still demonstrated a failure loads less than 50% of the intact model. This investigation suggests that a cortical breach causes a loss of strength that is not completely restored by intramedullary fixation. Level of Evidence: II  相似文献   
34.
To express human papillomavirus (HPV) L 1 capsid protein in the recombinant strain of Shigella and study the potential of a live attenuated Shigella-based HPV prophylactic vaccine in preventing HPV infection, the icsA/virG fragment of Shigella-based prokaryotic expression plasmid pHS3199 was constructed. HPV type 16 L1 (HPV16L1) gene was inserted into plasmid pHS3199 to form the pHS3199-HPV16L1 construct, and pHS3199-HPV 16L1 was electroporated into a live attenuated Shigella strain sh42. Western blotting analysis showed that HPV 16L 1 could be expressed stably in the recombinant strain sh42-HPV 16L 1. Sereny test results were negative, which showed that the sh42-HPV16L1 lost virulence. However, the attenuated recombinant strain partially maintained the invasive property as indicated by the HeLa cell infection assay. Specific IgG, IgA antibody against HPV16L1 virus-like particles (VLPs) were detected in the sera, intestinal lavage and vaginal lavage from animals immunized by sh42-HPV 16L1. The number of antibodysecreting cells in the spleen and draining lymph nodes were increased significantly compared with the control group. Sera from immunized animals inhibited mufine hemagglutination induced by HPV 16L1 VLPs, which indicated that the candidate vaccine could stimulate an efficient immune response in guinea pig's mucosal sites. This may be an effective strategy for the development of an HPV prophylactic oral vaccine.  相似文献   
35.
Understanding how wheat (Triticum aestivum L.) plants under high temperature (HT) regulate lipid composition is critical to developing climate‐resilient varieties. We measured 165 glycerolipids and sterol derivatives under optimum and high day and night temperatures in wheat leaves using electrospray ionization‐tandem mass spectrometry. Levels of polar lipid fatty acyl chain unsaturation were lower in both heat‐tolerant genotype Ventnor and susceptible genotype Karl 92 under HT, compared with optimum temperature. The lower unsaturation was predominantly because of lower levels of 18:3 acyl chains and higher levels of 18:1 and 16:0 acyl chains. Levels of 18:3‐containing triacylglycerols increased threefold/more under HT, consistent with their possible role in sequestering fatty acids during membrane lipid remodelling. Phospholipids containing odd‐numbered or oxidized acyl chains accumulated in leaves under HT. Sterol glycosides (SG) and 16:0‐acylated sterol glycosides (ASG) were higher under HT than optimum temperatures. Ventnor had lower amounts of phospholipids with oxidized acyl chains under HT and higher amounts of SG and 16:0‐ASG than Karl 92. Taken together, the data demonstrate that wheat leaf lipid composition is altered by HT, in which some lipids are particularly responsive to HT, and that two wheat genotypes, chosen for their differing physiological responses to HT, differ in lipid profile under HT.  相似文献   
36.
在生长均匀的茶园喷施氰戊菊酯(fenvalerate),采摘施药后2 h和1 h、2 h、3 h、5 h、7 h、9 h、14 h、21天的茶树鲜叶加工成绿茶,用气相色谱法测定成茶、茶汤和茶渣中反式氰戊菊酯和顺式氰戊菊酯的含量,研究了氰戊菊酯在成茶、茶汤中的残留动态。结果表明:反式氰戊菊酯和顺式氰戊菊酯在成茶中的残留水平随施药间隔天数的增加呈下降趋势,20 mL/667 m2施药剂量下,分别由施药当天2 h的9.40 mg/kg和17.51 mg/kg减小到第21天的1.07 mg/kg和1.53 mg/kg,消解幅度为88.62%和91.26%,40 mL/667 m2施药剂量下,分别由施药当天2 h的20.37 mg/kg和38.67 mg/kg减小到第21天的1.94 mg/kg和3.06 mg/kg,消解幅度为90.49%和92.09%。茶汤中氰戊菊酯含量(y)与成茶中氰戊菊酯含量(x)呈二项式函数关系,反式氰戊菊酯的函数关系为y=-0.0007x2 0.0242x,顺式氰戊菊酯的函数关系为y=-0.0002x2 0.0114x。按我国标准饮茶摄入的氰戊菊酯占每日允许摄入量的0.049%,足以达到保护人体健康水平的要求。而按欧盟的标准,饮茶摄入的氰戊菊酯占每日允许摄入量的0.0019%,即在10-5水平上,这样的风险水平已接近对非阈效应化学物质的风险控制水平(10-6)。  相似文献   
37.
大肠杆菌表达的病毒样颗粒疫苗   总被引:1,自引:0,他引:1  
重组病毒样颗粒是病毒衣壳蛋白外源表达的重要形式,形态结构与天然病毒高度相似,位于纳米尺度的大小易于被免疫系统识别,可激发机体产生保护性免疫反应,且不含有病毒基因,因此,是一种理想的疫苗形式,也是基于结构进行疫苗设计的重要结构载体。目前已上市的乙型肝炎疫苗、人乳头瘤病毒疫苗和戊型肝炎疫苗等基因工程疫苗均采用病毒样颗粒形式。大肠杆菌表达系统被广泛用于基因工程药物的生产,具有安全性好、生产周期短、易于放大生产等优点,在病毒样颗粒疫苗应用上具有良好前景。本文综述了利用大肠杆菌研制戊型肝炎疫苗和人乳头瘤病毒疫苗的进展,特别是这些病毒样颗粒疫苗的表达及组装、表位结构特征和临床试验结果。  相似文献   
38.
刘菲  杨志平  赵弘  汪辉  贾瑞春 《生物磁学》2012,(28):5509-5512
目的:研究限制输血输液量在肝硬化食管胃底静脉曲张破裂出血患者治疗中的疗效。方法:将98例患者随机分为两组。治疗组(55例)采用限制输血输液量方法进行治疗,同时进行其它常规止血治疗。对照组(43例)采用相对无限制大量输血输液方法治疗,余治疗方法同治疗组。分别观察两组患者24h、48h、72h内出血停止情况和总有效率。结果:治疗组患者24h、48h、72h内出血停止例数和总有效率明显高于对照组患者。P〈0.01。结论:限制输血输液量在治疗肝硬化食管胃底静脉曲张破裂出血中的止血率高,其作用明显优于相对无限制输血输液量对其治疗的疗效。  相似文献   
39.
目的:探讨右关托咪定(dexmedetomidine,DEX)对行全凭静脉麻醉患者靶控输注(target controlled infusion,TCI)丙泊酚用量及拔管期间血流动力学的影响。方法:选择拟于全麻下行经鼻蝶窦垂体瘤切除术的患者30例(ASA I~II级),随机分为两组,每组15例。试验组(D组)给予DEX负荷剂量0.5μg·kg-1,注药时间15rain,继以0.3μg·kg-1·h-1持续输注至修补硬膜时;对照纽(N组)在相同时间给予等容量生理盐水。两组麻醉诱导方法相同,术中以脑电双频指数(bispectral index,BIS)为麻醉深度监测指标,根据BIS值调节丙泊酚血浆靶浓度维持麻醉。记录拔管期间收缩压(SBP)、舒张压(DBP)和心率(HR),并计算心肌氧耗指数(RPP);记录丙泊酚平均用量、用药前后BIS值、呼吸恢复时间、睁眼时间、拔管时间及术中不良反应。结果:①D组给予负荷剂量后,BIS值由(95±3)降至(77±11),差异有统计学意义(P〈0.01)。②与N组相比,D组丙泊酚用量减少28%,差异有统计学意义(P〈0.01)。⑧拔管期间SBP、DBP和HR与入室时比较,D组无明显变化,N组HR显著升高(P〈0.05);D组拔管期间SBP、DBP、HR和RPP明显低于N组(P〈0.05);④两组患者呼吸恢复时间、睁眼时间及拔管时间差异均无统计学意义;⑤两组不良反应(心动过缓、高血压、低血压)的发生率无显著性差异。结论:术中持续静脉输注DEX可减少TCI丙泊酚用量,能使BIS值进一步降低,产生良好镇静效应;同时可有效减轻拔管期间循环变化,降低RPP,减少心肌耗氧量,提高拔管质量。  相似文献   
40.
摘要 目的:观察瑞芬太尼靶控输注对宫颈癌根治术患者麻醉苏醒质量、应激反应及辅助T细胞(Th)1/Th2免疫平衡的影响。方法:按照随机数字表法将2023年1月到2023年6月期间我院接受的120例宫颈癌根治术患者分为舒芬太尼组(n=60,舒芬太尼麻醉)和瑞芬太尼组(n=60,瑞芬太尼麻醉)。对比两组的麻醉苏醒质量、应激反应指标[皮质醇(Cor)、去甲肾上腺素(NE)、血管紧张素1(Ang-1)、血管紧张素2(Ang-2)]、Th1/Th2免疫平衡指标[包括Th1、Th2及调节性T细胞(Treg)、Th1/Th2比值],术后记录不良反应发生情况。结果:与舒芬太尼组相比,瑞芬太尼组的应激呼吸恢复时间、睁眼时间、拔管时间更短(P<0.05)。术后1 d,两组Cor、NE、Ang-1、Ang-2升高,但瑞芬太尼组低于舒芬太尼组(P<0.05)。术后1 d,两组Th1、Treg、Th1/Th2升高,但瑞芬太尼组低于舒芬太尼组;Th2下降,但瑞芬太尼组高于舒芬太尼组(P<0.05)。两组不良反应发生率组间对比未见差异(P>0.05)。结论:瑞芬太尼靶控输注用于宫颈癌根治术患者,可改善麻醉苏醒质量,减轻应激反应,调节Th1/Th2免疫平衡,且不增加不良反应的发生率,效果较好。  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