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排序方式: 共有1212条查询结果,搜索用时 31 毫秒
1.
阶梯形修理复合材料层合板拉伸性能研究   总被引:1,自引:0,他引:1  
为获得不同参数对阶梯形修理结构拉伸力学性能的影响,本文开展了试验研究.针对铺层数目为8层的复合材料层合板,分别研究了阶梯数目为2个、4个和8个的无附加层的情况.另外针对4个阶梯的情况,研究了附加层数目的影响.作为对比,对相同修理区大小情况下的斜切形挖补修理结构也进行了测试.结果显示,对阶梯形修理结构,拉伸强度随阶梯数目的增加而增加,当阶梯数目由2个增加到8个时,修理接头的强度恢复率由36%增加到67%.通过引入附加层能够有效的提高修理结构的强度,但随着附加层的引入以及附加层数目的增加,修理结构强度的分散性变大.阶梯形修理和斜切形挖补修理的对比显示,相同修理面积的情况下,由于斜切形挖补修理能够提供更加均匀的胶膜应力分布,斜切形挖补的修理效率要高于阶梯形修理,相比4个阶梯的阶梯形修理,斜切形挖补修理强度能够提高25%.最后,根据修理接头表面各点的应力/应变分布规律,获得了拉伸载荷作用下修理接头的失效机理和失效过程.  相似文献   
2.
We plan the manpower supply for aircraft line maintenance, taking into account two types of stochastic incidents: manpower demands for a flight and the number of aircraft needing to be serviced at one time. The problem is solved to find the shift and maintenance group combinations best suited for the given airline. The optimal aircraft maintenance certification for a crew is also analyzed to improve the entire manpower structure. In addition, the addition of temporary manpower required for actual daily operations is also considered as a part of understanding the total manpower utilized in actual operations. An integrated method including scenario generation and a stochastic model is developed to deal with the problem. Finally, we perform a case study based on operating data obtained from a major airline in Taiwan. The results and findings are compared with the airline’s current manpower plan in the discussion, and suggestions for improvement are made.  相似文献   
3.
In this paper, we extend the Bonferroni mean (BM) operator with the picture fuzzy numbers (PFNs) to propose novel picture fuzzy aggregation operators and demonstrate their application to multicriteria decision making (MCDM). On the basis of the algebraic operational rules of PFNs and BM, we introduce some aggregation operators: the picture fuzzy Bonferroni mean, the picture fuzzy normalized weighted Bonferroni mean, and the picture fuzzy ordered weighted Bonferroni mean. Then, a new picture fuzzy MCDM method is proposed with the help of the proposed operators. Lastly, a practical application of proposed model is given to verify the developed model and related results of the proposed model is compared with the results of the existing models to indicate its applicability.  相似文献   
4.
The number of receptors expressed by cells plays an important role in controlling cell signaling events, thus determining its behaviour, state and fate. Current methods of quantifying receptors on cells are either laborious or do not maintain the cells in their native form. Here, a method integrating highly sensitive bioluminescence, high precision microfluidics and small footprint of lensfree optics is developed to quantify cell surface receptors. This method is safe to use, less laborious, and faster than the conventional radiolabelling and near field scanning methods. It is also more sensitive than fluorescence based assays and is ideal for high throughput screening. In quantifying β1 adrenergic receptors expressed on the surface of H9c2 cardiomyocytes, this method yields receptor numbers from 3.12 × 105 to 9.36 × 105 receptors/cell which are comparable with current methods. This can serve as a very good platform for rapid quantification of receptor numbers in ligand/drug binding and receptor characterization studies, which is an important part of pharmaceutical and biological research.  相似文献   
5.
A methodology is proposed to reduce the cost and capital intensity of small-scale chemical processes by creating new opportunities for economies of numbers through standardizing the equipment designs across multiple processes. We depart from asynchronous design of single-processes and adopt a common-functionality based simultaneous design of multiple processes that use similar unit operations. A generalized cost function is used to appropriately balance the trade-offs between economies of scale and economies of numbers. An optimization-based framework for design standardization is developed and illustrated using two case studies. The first involves the simultaneous synthesis of methanol and ammonia processes, and the second addresses the optimal synthesis of multi-column natural gas liquid (NGL) fractionation processes for different natural gas sources. We observe that considerable reduction in capital intensity of small-scale processes is possible through equipment standardization.  相似文献   
6.
针对层次分析法(AHP)处理可靠性分配问题时存在的局限性,将直觉梯形模糊数与层次分析法相结合,提出了一种新的数控机床可靠性分配方法。在确定影响机床可靠性分配的重要因素种类及分配原则后,利用层次分析法确定数控机床可靠性分配问题的层次模型和可靠性分配中影响因素的重要性权重。运用直觉梯形模糊数准确表达出模糊信息和专家意见,最终确定子系统在可靠性分配中的分配比例。以一数控机床为例,通过和层次分析法进行对比,证明了该方法的有效性。  相似文献   
7.
磁阻式旋转变压器主要用于伺服控制系统中,针对极槽配合方式选择的问题,将信号绕组极对数引入到正弦绕组匝数计算中,推导出磁阻式旋转变压器定子齿数、信号绕组极对数和转子极对数之间的配合关系,并通过有限元仿真和样机试验验证了极槽配合方式的可行性。由极槽配合方法,信号绕组的极对等于转子极同一个定子可以与不同  相似文献   
8.
The hydrogen (H) diffusion process is a crucial issue related to storage of plutonium safely. In this work, first-principles GGA + U calculation is performed to elucidate the hydriding and diffusion behaviors of an additional H atom (Hi) in “perfect” PuH2+x (0 x 1) matrixes. It finds the value of incorporation energy increases with increasing x. The interaction energies show that an extra Hi atom interacts much further with surrounding host atoms in PuH3 than in other Pu hydride matrixes. The minimum migration paths of a Hi atom in PuH2+x are characterized by the image nudged elastic band (CINEB) method. The Hi atom diffuses in PuH2, PuH2.25, and PuH5 matrixes through directly migrating from an octahedral interstice to its nearest octahedral site with energy barriers of 1.36 eV, 1.15 eV, and 1.59 eV, respectively. Oppositely, the metastable IH-site plays a dominant role for the Hi migration into the O-site in PuH2.75. The diffusion path of the Hi atom in PuH3 is IPu  IH0160  IPU path with the lowest migration energy of 0.72 eV, which concludes the Hi has relatively higher mobility in PuH3. These findings provide detailed insight into how the H atom corrodes the Pu metal by connecting H atom diffusion in PuH2, PuH3, and intermediate compositions, which can be great interest for assisting the development of the new nuclear fuel for next generation reactors.  相似文献   
9.
Integer decisions on stage numbers and feed locations, and global optimality are still challenging for rigorous optimization of distillation processes. In the present article, we propose a smooth penalty function method to address both these problems. The proposed method is based on the relaxation of the integer decision problem into continuous nonlinear programming (NLP) problem by adopting the bypass efficiency model developed by Dowling and Biegler. A smooth penalty term (SPT) is proposed and added to the total annual cost (TAC) function to form a new objective function, namely, the smooth penalty function. Using the new objective function, the problem is initially solved with negative weight coefficients for the SPTs regarding each column section to get an optimum near the global optimum of the SPT. Then, starting from this solution, the problem is solved again iteratively by increasing the values of the weight coefficients until all the stage numbers become integers. The performance of the method is validated by an illustrating problem and in three case studies, including a reactive distillation optimization problem.  相似文献   
10.
Failure mode and effects analysis (FMEA) is a widely used risk assessment tool for defining, identifying and eliminating potential failures or problems in products, process, designs and services. Two critical issues of FMEA are the representation and handling of various types of assessments and the determination of risk priorities of failure modes. Many different approaches have been suggested to enhance the performance of traditional FMEA; however, deficiencies exist in these approaches. In this paper, based on a more effective representation of uncertain information, called D numbers, and an improved grey relational analysis method, grey relational projection (GRP), a new risk priority model is proposed for the risk evaluation in FMEA. In the proposed model, the assessment results of risk factors given by FMEA team members are expressed and modeled by D numbers. The GRP method is used to determine the risk priority order of the failure modes that have been identified. Finally, an illustrative case is provided to demonstrate the effectiveness and practicality of the proposed model.  相似文献   
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