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471.
介绍了一种双正激电路的软开关拓扑,分析了其软开关的工作原理,推导了实现软开关的关键技术参数的计算公式并采用该技术开发了1.8kW的充电电源。 相似文献
472.
Colin Robinson 《Small Wars & Insurgencies》2017,28(2):385-400
The search continues for methods to improve security for development in Sub-Saharan Africa. One of the important actors in this security arena is Sub-Saharan African governments’ armies. Much of their capability to meet security challenge depends on how militarily professional they are. The wave of democratic evolution in Africa since 1990 also affected military professionalism. This article reviews three models for assessing how democratisation might affect military professionalism in Sub-Saharan Africa, with special attention to post-conflict states. This should make it possible to decide which analytical methods are most appropriate to measure military professionalism in the particular circumstances of Sub-Saharan African post-conflict democratisation. Depending upon the particular nation-state in question, this decision on analytical methods may be useful for other Sub-Saharan states as well. 相似文献
473.
针对纤维织物复合材料的组分材料体分比测定问题,提出一种基于显微CT图像的测定方法。该方法可以通过不同尺度的显微CT图像分别测定全局纤维体分比、局部纤维体分比和纤维束体分比参数,还可以为难以用常规物理实验测定体分比的复合材料组分材料体积分数测定提供解决方案。以E-Glass/Epoxy纤维织物复合材料为研究对象,对比ASTM D3171 Procedure G、扫描电镜实验和显微CT实验三种测定法的测量值,结果证明了显微CT实验测定法的可行性和合理性。针对扫描电镜图像和显微CT图像,分别给出了相应的图像处理方法,为获得正确的组分材料分割结果提供了技术保证。显微CT实验测定方法可以广泛应用于复合材料组分材料体分比的测定。 相似文献
474.
475.
为研究掺砂率对高庙子膨润土一砂混合型缓冲/回填材料液塑限的影响,利用液塑限联合测定仪进行了试验研究,并运用最小二乘法对混合物液塑限试验数据进行了分析。试验结果表明膨润土一砂混合物的可塑性、液塑限值和塑性指数均随掺砂率的增大而降低。对试验结果进行分析,得到了考虑掺砂率影响的混合物液塑限经验公式。混合物的液塑限并不是随掺砂率增大成比例降低,而是液限的实测值小于理论值,塑限的实测值大于理论值。得到的不同掺砂率的膨润土一砂混合型缓冲/回填材料液塑限试验数据可为高放废物深地质处置库建设提供科学依据。 相似文献
476.
利用TRNSYS软件对重庆夏季建筑屋顶太阳能光电热一体化系统进行瞬态模拟分析计算,得到系统瞬时发电量与一段时间内累计发电量,光电热模块瞬时进出水温度与太阳能平板集热器瞬时进出水温度,系统一段时间内光电热模块累计有效得热量与一段时间内太阳能平板集热器累计有效得热量,系统的光电转换效率、光热转换效率以及太阳能综合利用效率。结果表明,建筑屋顶太阳能光电热一体化系统是重庆地区建筑太阳能光电热一体化系统适宜的型式。 相似文献
477.
478.
Small countries may not be able to afford all force elements (army, navy, air-force) operated by larger countries and certainly cannot afford all sub-elements (aircraft carriers, submarines, etc). This paper provides a framework for a small country to analyse its force structure, examining the influence of objectives, international co-operation, funding and technological constraints, and uncertainty. We analyse when a small country may choose to retain a balanced structure (with each force element) and when it may choose to drop one or more elements. The issues are illustrated with the decision by the New Zealand government over whether to retain a strike aircraft capacity. 相似文献
479.
Michael W. Chinworth 《Defence and Peace Economics》2013,24(2):369-401
Defense budgets in Japan have been complicated compromises from numerous inputs ‐ including threat perceptions, domestic industrial/technological base development, support for the bilateral security treaty with the United States and internal bureaucratic politics ‐ but with the fall of the former Soviet Union, the clearest justification for higher spending disappeared. Double‐digit defense spending increases that were common in the 1980s have been replaced by annual increases lower than present inflation rates, resulting in negative real growth in the country's defense budget. Domestic economic problems and consistent government pressures for smaller budgets have further slowed annual growth in total spending and have contributed to lower procurement budgets. As a result, the domestic Japanese defense industry is facing far more constrained conditions from the growth years of a decade before. Government policymakers are examining Japan's regional security environment as well as its alliance with the United States to determine the appropriate course for the country to take in the coming years. The formal security treaty with the United States is likely to remain a major element of government positions, but other aspects of the country's overall security posture are open to debate. Perceptions of a reduced threat environment are fueling additional pressures for defense budget cuts. The domestic defense industry seeks means to assure its survival in domestic defense markets in this constrained environment. Expansion into overseas markets to offset declining domestic markets is an option that currently is constrained by policy restrictions on arms exports. Industry is advocating re‐examination of those policies and unlike earlier years, government appears willing to respond positively but cautiously to this lobbying. 相似文献
480.
Martin Schönteich 《African Security Review》2013,22(4):34-44
In recent international armed conflicts private security contractors (PSCs) have played an ever increasing role and military advisors and tribunals are facing the dilemma of assessing the primary and secondary status of PSCs under international humanitarian law. In this article the misconception that PSCs are necessarily mercenaries will be dispelled. The possibility that PSCs might be categorised as combatants or civilians will then be explored. The conclusion is that where they are incorporated into the armed forces of a state, PSCs might attain combatant status. However, given that states are reluctant to formally incorporate PSCs into their armed forces, they will most likely remain essentially civilian. Their degree of participation in hostilities will determine whether they retain their immunity under international humanitarian law from attack and prosecution (as civilians) or whether they are rendered unlawful belligerents. 相似文献