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1.
Composite laminate structures remain an important family of materials used in cutting-edge industrial areas. Building efficient numerical modeling tools for high-frequency wave propagation in order to represent ultrasonic testing experiments of these materials remains a major challenge. In particular, incorporating attenuation phenomena within anisotropic plies, and thin intermediate isotropic layers between the plies often represent significant obstacles for standard numerical approaches. In our work, we address both issues by proposing a systematic study of the fully discrete propagators associated to the Kelvin-Voigt, Maxwell, and Zener models, and by incorporating effective transmission conditions between plies using the mortar element method. We illustrate the soundness of our approach by proposing intermediate one-dimensional and two-dimensional numerical evidence, and we apply it to a more realistic configuration of a curved laminate composite structure in a three-dimensional setting.  相似文献   
2.
The integration of computer theory and practice in higher vocational colleges is the necessary condition to realize the train- ing of professional talents and improve the comprehensive quality of skilled talents. It is also the problem that needs to be solved first in the teaching of computer major in higher vocational colleges. This paper firstly introduces the definition and connotation of the integration of computer theory and practice, discusses on its construction objectives and basic concepts, then analyzes the con- struction value of the integration of computer theory and practice, including the contents of employment, professional teaching, cur- riculum supporting and qualification examination, finally discusses on the construction scheme of the training room of the integra- tion of computer theory and practice, and gives the objective evaluation of the construction results, hoping to effectively improve the level of the integration of computer theory and practice, and achieve the sustainable development of teaching.  相似文献   
3.
该研究将室温等离子(ARTP)诱变与微生物微滴培养(MMC)技术应用于几丁质脱乙酰基酶(CDA)高产菌株的诱变选育,构建高产CDA菌株的诱变及高通量筛选方法。结果表明,经过4轮的ARTP诱变及MMC筛选,从200个不同的液滴中共筛选出5个发酵产酶明显提升的液滴,并通过进一步的平板筛选、24-深孔板复筛,获得了17株产酶提高300%以上的诱变菌株。通过对比分析17株高产菌株产CDA的能力,确定了1株最佳CDA高产菌株B4,其CDA最大产量比出发菌株提高了3.15倍,发酵产酶总量达到419.11 U/mL,为原始菌种的3.90倍。该研究为CDA高产菌株的诱变选育及高通量筛选提供了借鉴。  相似文献   
4.
刘斌 《现代矿业》2018,34(11):156-158
职业性噪声聋是指人们在工作中长期接触生产性噪声而形成的一种进行性感音性听觉障碍。职业性噪声聋患者与其接触噪声的时间、强度,特别是噪声作业工龄有极大关系。以某地下开采矿山为例,采用移动式隔声室对该矿井下凿岩机的工作噪声进行治理,并对移动式隔声室的具体技术参数和功能进行了探讨。现场实践表明:使用移动式隔声室后能够有效降低现场作业人员的噪声伤害,对于地下开采矿山噪声防控具有一定的借鉴价值。  相似文献   
5.
Proposing efficient numerical modeling tools for high-frequency wave propagation in realistic configurations, such as the one appearing in ultrasonic testing experiments, is a major challenge, especially in the perspective of inversion loops or parametric studies. We propose a numerical methodology addressing this challenge and based upon the combination of the spectral finite element method and the mortar element method. From a prior decomposition of the scene of interest into “macro-elements,” we show how one can improve the performances of the standard finite element procedures in terms of memory footprint and computational load. Additionally, using this decomposition, we are able to efficiently reconstruct important modeling features on-the-fly, such as orientations of anisotropic materials or splitting directions of perfectly matched layers formulations, altogether in a robust and efficient manner. We believe that this strategy is particularly suitable for parametric studies and sensitivity analysis. We illustrate our strategy by simulating the propagation of an ultrasonic wave into an immersed and curved anisotropic laminate 3D specimen flawed with an internal circular delamination of varying size, thus showing the efficiency and the robustness of our approach.  相似文献   
6.
Fishes typically occupy a species-specific temperature range, with their occupied depth being related to the lake’s temperature profile. When a fish’s preferred temperature range coincides with the thermocline, the location of their preferred thermal habitat is influenced by the rise and fall of internal waves, leading to possible changes in fish depth. These internal waves are common in large, stratified lakes, yet we do not know how they affect the spatial distribution and behavior of freshwater fishes. We conducted nighttime hydroacoustic surveys in a large, deep embayment of a large thermally stratified lake to observe whether pelagic fish respond to vertical oscillations of the thermocline caused by internal waves. The coldwater pelagic fish in our study (primarily cisco, Coregonus artedi) typically occupied a narrow vertical band approximately 5–8 m thick and temperatures between 10.8 ± 0.8–13.6 ± 1.6 °C (fishes sized 106–500 mm), just below the thermocline (centered around 15–17 °C). Importantly, the upper bound of fish depth varied in response to vertical thermocline movements associated with internal waves, suggesting fish respond to changes in their physical environment on timescales commensurate with basin-scale internal wave periods (hours to days), to remain within their preferred thermal habitat. Dissolved-oxygen levels were typically above avoidance thresholds of these fish, thus not likely exerting a strong influence on fish location. Our findings emphasize the need to account for internal waves when designing hydroacoustic and netting surveys, as thermocline movements can influence where fish are located.  相似文献   
7.
随着我国放射诊断学的快速发展,当前许多医院都在购置或使用医用数字化X射线摄影系统(DR)机房建设必须符合国家标准满足临床使用。本文结合日常工作中总结的经验,从DR机房的规划设计、放射防护设施施工、放射防护验收监测方面探讨了DR机房建设过程中的要点,为医院的机房建设提供参考。  相似文献   
8.
The concept of thermal energy storage in building gains a specific importance in the present energy scenario related to energy consumption and indoor thermal comfort. The material used to store the thermal energy which undergoes a phase change referred as PCM and it is considered as a possible solution for reducing energy consumption in the building by storing and releasing heat within a certain temperature range; it raises the building inertia and also stabilizes indoor air temperature fluctuations. The room temperature is controlled by imposing PCM inside the walls. An attempt has been made to compare room air temperature with and without the use of PCM inside the walls of constructed modular building unit. The PCM imposed modular building shows the reduced temperature fluctuations in room, the PCM absorbs and liberates excess heat which is gained from the outer side of the room and maintains constant inner room temperature. The PCM imposed walls of modular building unit have an ability to reduce 10–30% of heat load in comparison with the plain wall. The results showed that reduction in room temperature is about 2–4°C and it has been concluded that the PCM imposed modular building unit has more energy saving opportunities than normal modular building unit.  相似文献   
9.
对三坐标测量机(CMM)的分类和结构形式进行分析,围绕三坐标测量室设计中的选址、起吊方式、暖通空调、地坪、隔振、照明等问题进行探讨.结合设计实践,重点针对待测工件的起吊运输方式,给出相应的解决方案,并分析了各种方案的优缺点.  相似文献   
10.
有效地通风和合理的气流组织对于改善室内空气品质,控制室内污染物浓度,对实现健康建筑、舒适性空调有着重要的意义。室内空调气流组织方式多种多样,对其效果的研究也很多,但是多集中在理论分析,而对气流组织效果的监测方面的研究较少,且监测方法没有一个完成的体系。首先对空调气流组织现场监测和评价方法进行分析,得知现场检测方法多以工程标准,只是对室内气流组织的应用效果进行评价,并不能完全反映气流组织的轨迹特征。其次,为了更好的反映不同时刻空调气流组织的特征,建立气流组织的监测方法,以5m×3m×2.8m的一个典型实验房间为例,利用计算模拟方法,分析不同气流组织形式下温度、风速等衰减特征,为室内气流组织现场智能监测测点布置提供依据。  相似文献   
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