关于中国近代史上限的几点思考     

严亚明 《青海师专学报》2002,22(3):28-32

“近代”一词有两种含义，指时间或社会发展形态。中国史学界“近代”、“现代”说法的指称对象虽渐趋一致，但实际教学、科研中，二者相混，难以硬性规范。“近代”应明确为指半殖民地半封建社会史，其上限以鸦片战争为标志，但只具相对意义，近代史时段－鸦片战争至中华人民共和国成立，亦不能作僵化理解，应根据具体研究对象来确定研究的时空范围，淡化“上限”概念，拓展中国近代史研究视野，在理为 宏大的历史时空中考察中国近代社会历史的走向，将是中国近代史学科新的突破和发展的契机。  相似文献   

关于一个平面1-集的不规则性     

买买提艾力·喀迪尔 《喀什师范学院学报》2011,32(6):13-14,35

一个S-集必定是不规则集,除非S是整数.但S是整数的时候这个S-集可能是规则的,也可能是不规则的.为此,利用上密度和下密度来证明一个平面1-集的不规则性.  相似文献   

开采上保护层效果检验技术研究     

张志勇  徐传田 《淮南职业技术学院学报》2011,(3):1-3

煤与瓦斯突出严重影响了矿井安全生产,开采保护层是最有效、最经济的防治措施;通过对海孜矿上保护层开采效果研究,结果表明：开采前后瓦斯压力及含量降低明显,卸压区内瓦斯抽采率可达33.2%;卸压区内煤层透气性系数比未卸压区的增大三倍;相似模拟实验表明9煤的膨胀率为8.1‰,综合分析确定开采上保护层后对9煤起到了明显的卸压保护作用,研究结果为相似条件下保护层开采提供了参考。  相似文献   

赤水河上游墨头鱼年龄与生长研究     

赵海涛  王剑伟  刘丽  胡思玉  陈永祥 《毕节学院学报》2011,29(4):106-111

对赤水河上游国家级鱼类保护区内的墨头鱼标本进行了年龄鉴定,渔获物的年龄结构由0～8龄共9个龄组组成,以低龄个体为主,2～5龄个体占83.07%。体长和体质量呈幂函数关系且幂指数接近3,属于匀速生长类型,因此用Von Bertalanffy方程描述其生长特性,相关生长参数分别为:渐近体长L∞=323.0227mm,渐近体质量W∞=824.7102g,k=0.1781,t0=-1.4655龄。体质量生长拐点年龄Ti=4.77龄,对应体长、体质量分别为Lt=333.14mm,Wt=746.06g。由于捕获物中以低龄个体为主,呈现小型化趋势,建议将其捕捞年龄确定为5龄以保护核心区内的墨头鱼资源。  相似文献   

Concreteness fading in learning secondary school physics concepts     

《Learning and Instruction》2022

Concreteness fading has been proposed as a general instructional approach to support learning of abstract mathematics and science concepts. Accordingly, organizing external knowledge representations in a three-step concrete-to-idealized sequence should be more beneficial than the reverse, concreteness introduction, sequence. So far, evidence for the benefits of concreteness fading come mainly from studies investigating learning of basic mathematics concepts. Studies on learning natural science concepts are scarce and have not implemented the full three-step-sequence. In an experimental classroom study (N = 70), we compared concreteness fading and concreteness introduction in high school science education about electromagnetic induction using a detailed assessment. Furthermore, we explored whether these sequences differentially affect the use of the different representations during instruction. Both sequences were equally effective and there were no differences in using the representations. We discuss why our results question the proposed advantages of concreteness fading and highlight conceptual differences and learning goals across domains.  相似文献   

基于消除江西新办地方高校发展的成长上限的管理对策研究     

史术光  贾仁安 《科技广场》2011,(8):71-74

高校扩招十年以来,中国高等教育进入了新的历史阶段,同时在高校扩招发展的过程中出现了一系列的发展上限问题。本文基于系统动力学基模分析的方法,在充分分析江西新办地方高校发展的成长上限基模的基础上,根据系统动力学成长上限基模消除理论,构建消除影响两地旅游合作发展上限的对策基模,提出相应的管理对策。  相似文献   

Clinical implications of exercise immunology     

David C. Nieman 《运动与健康科学(英文)》2012,1(1):12-17

Maintaining leanness and a physically active lifestyle during adulthood reduces systemic inflammation, an underlying factor in multiple chronic diseases. The anti-inflammatory influence of near-daily physical activity in lowering C-reactive protein, total blood leukocytes, interleukin-6, and other inflammatory cytokines may play a key role in lowering risk of cardiovascular disease, certain types of cancer, type 2 diabetes, sarcopenia, and dementia. Moderate exercise training causes favorable perturbations in immunity and a reduction in incidence of upper respiratory tract infection (URTI). During each bout of moderate exercise, an enhanced recirculation of immunoglobulins, neutrophils, and natural killer cells occurs that persists for up to 3-h post-exercise. This exercise-induced surge in immune cells from the innate immune system is transient but improves overall surveillance against pathogens. As moderate exercise continues on a near-daily basis for 12–15 weeks, the number of symptoms days with URTI is decreased 25%–50% compared to randomized sedentary controls. Epidemiologic and animal studies support this inverse relationship between URTI risk and increased physical activity.  相似文献   

矿井复杂通风网络的三角形与星形变换解法     

刘兴杜 《北京工业职业技术学院学报》2004,3(4):45-48,52

把复杂电路中三角形与星形联接等效变换原理引入矿井复杂通风网络的研究,导出解复杂风网的等效变换公式,并运用成功.以往的解算基本上是迭代逼近法,本法则解决了复杂风网风量自然分配的直接计算问题,因而过程简便,同时也使矿井复杂通风网络的化简成为现实.该方法除了适用矿井通风外,还有可能适用于其它领域相关的解算.  相似文献   

Gender diversity in senior management,strategic change,and firm performance: Examining the mediating nature of strategic change in high tech firms     

《Research Policy》2019,48(7):1681-1693

Only recently have enough women joined senior leadership positions in high tech firms for research on senior management gender diversity in high tech industries to be possible. We propose that senior management gender diversity fosters strategic change in high tech firms, especially under conditions where alliance formation intensity and top management team (TMT) educational background diversity are high, because the breadth of opportunity and knowledge associated with these conditions facilitates implementation of new ideas. Results show that both inter-organizational strategic alliance formation intensity and TMT educational background diversity positively moderate the relationship between senior management gender diversity and strategic change. We also find support for a moderated mediation model whereby a gender-diverse senior management positively impacts strategic change, which ultimately improves firm performance when the firm exhibits high alliance formation intensity and has a TMT that is diverse across educational background.  相似文献   

一类广义隐拟向量变分不等式解的存在性问题     

赵佃波  何中全  李克勤 《宜宾学院学报》2008,8(6)

本文研究了Hausdorff空间中一类广义隐拟向量变分不等式问题（GIVQ1）,利用不动点定理得到了解的存在性定理,给出了（GIVQI）若干推论．  相似文献