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1.
TQFR-3000型同步牵引发电机在考虑电压电流的限制条件下,为了充分利用柴油机的功率,同步牵引发电机外特性曲线和功率曲线应该保持在理想状态。而同步牵引发电机所拥有的自然外特性曲线,无法使柴油机保持恒定功率。通过对TQFR-3000型同步牵引发电机的外特性曲线进行分析并调节,使同步牵引发电机的外特性曲线和功率曲线达到理想状态。 相似文献
2.
为解决对称密码中s盒和非线性布尔函数(NBF)在实现密码专用处理器时采用异构化设计导致的资源浪费问题,提出一种类AESs盒和NBF的可重构电路结构方法。分析s盒问题中的原有非线性布尔函数模块(NBFM),4-4、6-4的s盒电路能够提供更好的适配性,但不能很好地支持8-8的s盒电路。基于塔域分解理论,论证不同的类AESs盒电路差异在于输入前后的转换矩阵。采用混合基的方法将类AESs盒电路分解成GF (16)上的各个运算模块,并推导出模块比特级别表达式,在具体适配运算模块时采取门级实现、NBFM适配实现或对NBFM进行改进3种方案,实现类AESs盒和NBF的可重构电路。实验结果表明,该方法在不影响原有NBF功能的基础上,利用4个NBFM与22.7%的s盒电路面积即可实现一个完整的类AESs盒电路。 相似文献
3.
Wireless Sensor Network is considered as the intermediate layer in the paradigm of Internet of things (IoT) and its effectiveness depends on the mode of deployment without sacrificing the performance and energy efficiency. WSN provides ubiquitous access to location, the status of different entities of the environment and data acquisition for long term IoT monitoring. Achieving the high performance of the WSN-IoT network remains to be a real challenge since the deployment of these networks in the large area consumes more power which in turn degrades the performance of the networks. So, developing the robust and QoS (quality of services) aware energy-efficient routing protocol for WSN assisted IoT devices needs its brighter light of research to enhance the network lifetime. This paper proposed a Hybrid Energy Efficient Learning Protocol (HELP). The proposed protocol leverages the multi-tier adaptive framework to minimize energy consumption. HELP works in a two-tier mechanism in which it integrates the powerful Extreme Learning Machines for clustering framework and employs the zonal based optimization technique which works on hybrid Whale-dragonfly algorithms to achieve high QoS parameters. The proposed framework uses the sub-area division algorithm to divide the network area into different zones. Extreme learning machines (ELM) which are employed in this framework categories the Zone's Cluster Head (ZCH) based on distance and energy. After categorizing the zone's cluster head, the optimal routing path for an energy-efficient data transfer will be selected based on the new hybrid whale-swarm algorithms. The extensive simulations were carried out using OMNET++-Python user-defined plugins by injecting the dynamic mobility models in networks to make it a more realistic environment. Furthermore, the effectiveness of the proposed HELP is examined against the existing protocols such as LEACH, M-LEACH, SEP, EACRP and SEEP and results show the proposed framework has outperformed other techniques in terms of QoS parameters such as network lifetime, energy, latency. 相似文献
4.
Tanzila Saba Mirza Naveed Shahzad Sonia Iqbal Amjad Rehman Ibrahim Abunadi 《计算机、材料和连续体(英文)》2022,71(3):4785-4801
Many countries developed and increased greenery in their country sights to attract international tourists. This planning is now significantly contributing to their economy. The next task is to facilitate the tourists by sufficient arrangements and providing a green and clean environment; it is only possible if an upcoming number of tourists’ arrivals are accurately predicted. But accurate prediction is not easy as empirical evidence shows that the tourists’ arrival data often contains linear, nonlinear, and seasonal patterns. The traditional model, like the seasonal autoregressive fractional integrated moving average (SARFIMA), handles seasonal trends with seasonality. In contrast, the artificial neural network (ANN) model deals better with nonlinear time series. To get a better forecasting result, this study combines the merits of the SARFIMA and the ANN models and the purpose of the hybrid SARFIMA-ANN model. Then, we have used the proposed model to predict the tourists’ arrival in New Zealand, Australia, and London. Empirical results showed that the proposed hybrid model outperforms in predicting tourists’ arrival compared to the traditional SARFIMA and ANN models. Moreover, these results can be generalized to predict tourists’ arrival in any country or region with a complicated data pattern. 相似文献
5.
通过浸泡实验和电化学测试研究了Mg-4.0Zn-0.2Mn-0.2Ca(质量分数)微细管的体外降解行为与腐蚀机理。结果表明,退火处理可以提高微细管的耐腐蚀性。长期浸泡实验表明腐蚀过程相对均匀,退火微细管在Hank''s溶液中的腐蚀速率约为0.30 mm/a。在浸泡初期,退火管材表面生成Mg(OH)2,形成保护膜,阻碍腐蚀进行。虽然Mg(OH)2膜上形成的羟基磷灰石(HA)可以进一步降低腐蚀速率,但是镁基体中粗大的第二相会增强电偶腐蚀效应,并且生成的大量氢气,从而破坏HA膜,使腐蚀继续进行。 相似文献
6.
Parkinson’s disease (PD) is an age-related neurodegenerative ailment that affects dopamine-producing neurons in a specific area of the brain called the substantia nigra of the ventral midbrain. It is clinically characterized by movement disorder and marked with unusual synaptic protein alpha-synuclein accumulation in the brain. To date, only a few Food and Drug Administration (FDA) approved drugs are available on the market for the treatment of PD. Nonetheless, these drugs show parasympathomimetic related adverse events and remarkably higher toxicity; hence, it is important to find more efficacious molecules to treat PD. In our study, We chosen 22 natural compounds as inhibitors that potentially block the alpha-synuclein clump—the pathological hallmark of PD—and provide new avenues for its treatment. Most of these molecules exhibited good pharmacokinetic behaviors, making them decisively favorable drug candidates to cure PD. Molecular docking studies were performed to investigate the binding interactions between natural compounds and alpha-synuclein as anti-Parkinson drug targets. Among the examined compounds, curcumin and piperine emerged as promising phytochemicals with the highest binding affinity, key residual stable bindings and showed a good inhibitory features. Thus, the present study indicates that curcumin and piperine hold the potential to be developed as treatment options against PD. Experimental validations are needed for insights into their mechanism of action and potential clinical application. 相似文献
7.
Renal cell carcinoma (RCC) has a poor prognosis due to limited diagnosis and treatment. Thus, it is necessary to find novel prognostic biomarkers and therapeutic targets. The aberrant expression of microRNAs plays an important role in RCC oncogenesis. Tissue inhibitors of metalloproteinase 3 (TIMP3) acts as a downstream target of miR-181b. The aim of this study was to understand the role and molecular mechanism of miR-181b in RCC oncogenesis. The results showed that miR-181b expression was significantly higher in RCC tumour tissues, especially in those with significant invasion or metastasis. miR-181b overexpression promoted proliferation and migration of the RCC cell line 786-O, while miR-181b knockdown had the opposite effect. In addition, miR-181b was inversely correlated with TIMP3 expression in RCC tumour tissues. miR-181b overexpression reduced TIMP3 expression in RCC cell line 786-O or OS-RC-2, while miR-181b knockdown had the inverse effect. Mechanistically, a luciferase reporter assay confirmed the binding sites of miR-181b on the 3’-UTR of TIMP3, confirming the targeting effect of miR-181b on TIMP3. Overall, miR-181b promotes the development and progression of RCC by targeting TIMP3 expression, indicating the potential use of miR-181b in the diagnosis and treatment of RCC. 相似文献
8.
工业机器人执行接触性作业任务时,通常需要稳定控制接触力,比如在磨抛过程中,不平稳的法向接触力容易影响表面质量。为解决力跟踪控制时法向控制速度易超调和不确定环境造成法向接触力不平稳的问题,提出一种基于模型预测控制的工业机器人曲面跟踪方法。首先,根据工件模型几何信息计算出末端工具的运动轨迹,再结合机器人当前位姿求解末端工具的笛卡儿速度;然后,建立末端工具与工件接触时的状态空间模型,并依据末端工具的姿态变化对法向阻尼系数进行在线调节;最后,根据实时力信号的反馈,利用模型预测控制算法对法向速度进行修正,实现曲面恒力跟踪。基于Staubli TX90工业机器人,在末端工具姿态不变和姿态改变的情况下分别进行了曲面跟踪实验,结果显示法向接触力波动范围分别为±1 N和±2 N,方差分别为0.038 1 N2和0.105 9 N2,能够达到较好的力跟踪效果。 相似文献
9.
针对过渡曲面加工表面质量往往比普通曲面更难控制的特殊性,开展与过渡面适应的速度规划、加工轨迹的局部优化等研究来改善过渡面的表面质量,并通过运动参数可视化来预测过渡面的加工质量。在一定变化范围内,使空间曲率、挠率具有连续性的连续程序段属于一个区间,以建立过渡面的刀具轨迹“同速区间”。在同速区间内建立弧长参数化、拟合递推式Akima样条曲线,实现刀具轨迹的局部优化。通过数控模拟软件采集运动参数(速度、加速度及电流等),生成的插补文件导入自主开发的运动参数可视化软件,形成可视化图以此来预估加工表面质量。分别对可乐瓶底与变曲率曲面的过渡面进行同速区间规划与轨迹优化,得到了优化前后的可视化图。进一步,验证预估表面质量的有效性,通过对变曲率过渡面和五指山零件实际加工,验证了加工表面质量提高与否与可视化图好坏的一致性。因此建立过渡面同速区间及运动参数可视化,以实现过渡面的质量预估及提升效果。 相似文献
10.
针对电力系统故障导致的电压暂降通过电-气耦合设备对系统造成多次影响的问题,提出了一种缓减电压暂降影响的电-气综合能源系统储气装置选址定容方法。分析了电力系统发生电压暂降事件对电-气综合能源系统的影响;基于灵敏度分析提出了天然气系统储气装置选址方法;综合考虑投资成本与效益,以安装储气装置后效益的最大值为目标函数,确定储气装置最佳配置方案。通过对由IEEE 14节点电力系统和11节点天然气系统构成的电-气综合能源系统进行算例分析,验证了该缓减方法的正确性与有效性。 相似文献