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991.
992.
采用红外吸收法测定钢中碳含量,对影响测定结果不确定度的各个因素如测量重复性、标准物质校准仪器的变动性、标准物质示值的不确定度、天平称量的不确定度、仪器分辨率引起的不确定度分量进行了评定,计算了相对合成标准不确定度和扩展不确定度。评定结果表明,在多次校准的前提下,标准物质校准仪器的变动性和标准物质示值的不确定度对总不确定度影响最大,其次是测量重复性。所以,在测定中应特别注意标准物质的选择和标准物质对仪器校准的变动性。 相似文献
993.
994.
995.
ABSTRACTThe corrosion of steels in clay soils is of interest for buried steel infrastructure. To obtain better information about the early corrosion effects, mild steel coupons were exposed for 3, 6 and 13 months in finely graded clay soil at different moisture contents and with different degrees of compression to simulate compaction. It was found that the maximum corrosion mass loss and pit depths occurred at a soil moisture content of 17–18?wt-% for all exposures and levels of compaction, corresponding to around 0.65 degree of saturation. These values are broadly consistent with earlier findings for non-clay soils. For exposures of 3 months corrosion was predominantly localised but subsequently became more uniform. This was shown to be consistent with good compaction of the soil against the steel surface. Poorly compacted lumpy clays, however, showed larger areas of localised corrosion and relatively greater corrosion mass loss and deeper pitting. 相似文献
996.
The experimental results show that the nature of formation of the structure of the surface layer in the weld edges influences the depth of the porous surface layer, the intensity and extent of adsorption capacity of contaminants and, correspondingly, the thermally activated process of solid-phase interaction ahead of the front of the solidified pool and the level of defectiveness (porosity) in the welded joint. 相似文献
997.
碳酸锂溶解度在工业结晶生产中是十分重要的基础数据。采用浸入式红外探头和拉曼探头在线监测溶液体系中CO32-和碳酸锂的特征峰峰强的变化,依据Lambert-Beer定律得出溶液体系中实时在线测定碳酸锂的溶解度。通过在线测定,测得碳酸锂在氯化钠-氯化钾溶液(cNaCl=0.446 6 mol/L,cKCl=0.015 8 mol/L)中的溶解度高于在水中的溶解度值。实验测试出的水中碳酸锂的溶解度数据还能与Van′t Hoff方程较好地关联,进一步测算碳酸锂在其他温度下水中的溶解度值。此外,该方法测定的碳酸锂在水中的溶解度数据比文献值中采用重量分析法测试出的溶解度数据偏小,是因为测试装置不同造成的。 相似文献
998.
Optimization of room-temperature TCR of polycrystalline La0.9-xSrxK0.1MnO3 ceramics by Sr adjustment
Hongjiang Li Kaili Chu Xingrui Pu Xiaohan Yu Xiaoli Guan Shuaizhao Jin Xiang Liu 《Ceramics International》2021,47(1):94-101
High-density La0.9-xSrxK0.1MnO3 ceramics (LSKMO, A-site = La, Sr and K, 0 ≤ x ≤ 0.25) are successfully fabricated by using facile sol-gel method. Electrical properties are performed by using combination of phenomenological percolation (PP) model, double exchange (DE) mechanism, and Jahn-Teller (JT) effect. Moreover, X-ray diffraction and scanning electron microscopy are employed to analyze the structure and morphology of LSKMO ceramics. Valence states and ionic stoichiometry are assessed by using X-ray photoemission spectrometry. Results reveal that Sr2+ ions, substituting La3+ ions, significantly influenced DE mechanism and JT effect. In addition, Sr-doping plays essential role in improving electrical properties of LSKMO ceramics. At optimal doping content of x = 0.09, peak temperature coefficient of resistance (TCR) of the resistivity is found to be 11.56% K?1 at 297.15 K, which is optimal TCR for A-site K-occupied perovskite manganese oxides. These results confirm that polycrystalline LSKMO ceramics render high room-temperature TCR values due to Sr-doping. 相似文献
999.
以聚砜(PSF)为原料,N,N‐二甲基甲酰胺(DMF)为溶剂,4,4'-二氨基二苯砜(DDS)和均苯四甲酸二酐(PMDA)为添加物,在聚砜铸膜液中“原位合成”聚酰胺酸(PAA),采用浸没沉淀相转化法制备高水通量PSF超滤膜。使用傅里叶变换红外光谱仪(ATR-FTIR)和X射线光电子能谱分析(XPS)对膜表面化学组成进行分析,结果表明成功在膜表面引入PAA。膜的荷电性、水接触角、保湿性和水通量等性能测试表明,改性膜具有良好的保湿性和水渗透性。在0.1 MPa的运行压力下,改性膜的纯水通量和牛血清白蛋白(BSA)截留率均高于纯PSF超滤膜,纯水通量从221.39 L/(m2·h)增加至406.57 L/(m2·h),截留率从75.75%增加到96.14%;在0.01~0.1 MPa的运行压力范围内,改性膜水通量均高于纯PSF超滤膜。。 相似文献
1000.
We developed an Internal Model Control (IMC) algorithm for drying a thin textile fabric, continuously passing through an electric infrared dryer, based on a reduced linear model of the drying dynamics. This model relates the controlled variables, the humidity and temperature of the web at the dryer outlet, to the manipulated variables, the electrical power supplied to the sources and the web speed through the dryer, and also to changes in the initial humidity of the web at the dryer inlet. The control algorithm was first tested by simulation using the model in regulation mode, and in set-point tracking mode, to vary the manipulated variables so as to maintain the controlled variables at their respective set-points when the inlet web temperature and humidity were changed. The performance under simulated operational conditions was compared to that of a conventional feedback proportional-integral (PI) controller coupled with a feedforward control. The IMC controller was then tested directly in regulation mode using a pilot scale infrared dryer, acting simultaneously on the manipulated variables, the emitter power and the web speed, to control the fabric temperature and humidity at the dryer outlet. The experimental results were compared with those from the above feedback-feedforward controller, on the pilot scale dryer. The results have indicated that the closed-loop stability of the process is assured simply by choosing a stable IMC controller. Also, such a controller does not require the design of specific compensators for the strong interactions between variables of the drying process. 相似文献