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61.
目的研究激光熔化沉积Al Si10Mg铝合金的成形特性及力学性能。方法以颗粒度45~105μm的Al Si10Mg粉末为材料,6061铝合金为基板,利用光纤激光器在充氩舱内分别进行单层单道、竖直薄壁单墙体与倾斜薄壁墙体的成形试验。测试单墙体的抗拉强度与延伸率,并通过扫描电子显微镜和光学显微镜对微观组织形貌进行分析。结果单层单道沉积层高度与激光扫描速度负相关,与送粉速度成线性正相关;而沉积层宽度与扫描速度负相关,与激光功率正相关。沉积单墙体时,沉积前10层最不稳定,墙体厚度低于后续层的厚度。为了使沉积过程稳定,墙体不塌陷,通过激光功率在前20层左右逐层递减,成功制备出250层(高10cm)以上的单墙体。工艺选取合适时,AlSi10Mg具有良好的成形能力,激光头角度保持竖直不变,墙体倾角60°以下可以稳定沉积。制备沉积态Al Si10Mg气孔率约3%,抗拉强度250MPa左右,延伸率5%以上,抗拉强度高于成分相似的ZL104铸件25%。微观组织内Al-Si共晶细小,没有针片状共晶组织,并且组织沿沉积方向呈现周期性变化。结论 Al Si10Mg在激光熔化沉积时具有良好的成形能力,沉积态的组织强度高于铸态组织强度。优化后的工艺可以稳定沉积制备下圆上方的变截面薄壁样件。 相似文献
62.
利用选区激光熔化成形技术制备了纯AlSi10Mg合金及碳纳米管(carbon nanotubes,CNTs)-AlSi10Mg复合材料。当添加CNTs含量为0.05%(质量分数)时具有一定增强效果,但随着CNTs添加量增大,复合材料性能却因为缺陷的增加而明显下降。木实验利用纳米CT技术对纯合金及CNTs(0.5%)-AlSi10Mg复合材料进行缺陷的三维重构。结果表明,添加0.5%的CNTs后,成形缺陷体积所占比例由12%增加至46%;气孔型缺陷数量明显增加,并且等效直径相对较大。CNTs在粉体中的团聚及对气体的吸附作用是两种类型缺陷增加的根本原因。 相似文献
63.
64.
用微波等离子体炬(MPT)为激发光源,氩气为等离子体工作气体,用气动雾化迚样,研究了微波等离子体炬原子发射光谱法(MPT-AES)测定抚顺环境样品中的重金属元素Pb,Cd,Cr,Cu,Mn的方法。考察了各微量元素的分析谱线,载气流量,工作气流量和微波向前功率对元素Pb,Cd,Cr,Cu,Mn的发射强度的影响,分析了酸浓度及共存离子对其测定的影响,得到了测量不同金属离子的最佳工作条件,在最佳条件下测量元素Pb,Cd,Cr,Cu,Mn的检出限分别为22.9,5.7,30.7,3.6,6.0 ng·mL-1,精密度分别为5.97%,4.92%,1.24%,1.54%,1.87%,加标回收率在84.6%-104.0%之间。 相似文献
65.
66.
Cloud computing infrastructures provide vast processing power and host a diverse set of computing workloads, ranging from service-oriented deployments to high-performance computing (HPC) applications. As HPC applications scale to a large number of VMs, providing near-native network I/O performance to each peer VM is an important challenge. In this paper we present Xen2MX, a paravirtual interconnection framework over generic Ethernet, binary compatible with Myrinet/MX and wire compatible with MXoE. Xen2MX combines the zero-copy characteristics of Open-MX with Xen's memory sharing techniques. Experimental evaluation of our prototype implementation shows that Xen2MX is able to achieve nearly the same raw performance as Open-MX running in a non-virtualized environment. On the latency front, Xen2MX performs as close as 96% to the case where virtualization layers are not present. Regarding throughput, Xen2MX saturates a 10 Gbps link, achieving 1159 MB/s, compared to 1192 MB/s of the non-virtualized case. Scales efficiently with the number of VMs, saturating the link for even smaller messages when 40 single-core VMs put pressure on the network adapters. 相似文献
67.
Wen‐Jing Ding Xiao‐Fang Wu Jia‐Sheng Zhong Jin‐Zhi Wan 《International Journal of Food Science & Technology》2014,49(7):1773-1779
This study explored the stability and degradation products of aloin A under varying pH, temperature and light conditions usually encountered in processing. The stability of aloin A was significantly affected by temperature and pH. The content of aloin A decreased by more than 90% within 12 h at 50 °C and within 6 h at 70 °C, respectively. A significant decrease in stability was also observed at higher pHs. At pH 8.0, less than 2% of aloin A remained within 12 h. However, aloin A exhibited good stability at acidic pH levels with 94% remaining at pH 2.0 for 14 days. Light exerted no influence on the stability during the experimental period (14 days). Aloe‐emodin, elgonica‐dimers A and B were characterised as major degradation products of aloin A at pH 5.0 or below, and elgonica‐dimers were mainly formed at 4 °C as well. 10‐hydroxyaloins A and B were found under any condition except at pH 2.0 and 3.0, and they were mainly formed under high temperature, neutral‐basic and any light conditions. 相似文献
68.
69.
《Drug development and industrial pharmacy》2013,39(10):1195-1200
ABSTRACTThe purpose of this investigation was to compare the bioavailability of three coenzyme Q10 (CoQ10) formulations in dogs using an open, randomized, multiple-dose crossover design. The formulations included a powder-filled capsule (A, control) and two soft gelatin formulations (Q-Gel ® as the water-miscible form of CoQ10, B and Q-Nol?as the water-miscible form of ubiquinol, the reduced form of CoQ10, C). Formulations were evaluated in pairs, allowing a washout period of 14 days prior to crossing over. Blood samples were collected from each animal prior to dosing to determine the endogenous plasma CoQ10 concentrations. Serial blood samples were collected for 72 hr and plasma CoQ10 concentrations were determined by high-performance liquid chromatography. Plasma concentration–time profiles were corrected for endogenous CoQ10 concentrations. Results showed that the relative bioavailabilities of formulations B and C were approximately 3.6 and 6.2-fold higher than that of control formulation A. The AUC(µg. hr/mL)±SD, Cmax(µg/mL)±SD, and Tmax(hr)± SD for formulations A, B, and C were 1.695±0.06, 6.097±0.08, and 10.510±0.10; 0.096±0.035, 0.169±0.038, and 0.402±0.102; and 4.2±1.48, 4.1±1.57, and 4.5±0.58, respectively. While no significant differences were observed between Tmax values of the three formulations, the AUC and Cmax values for formulations B and C were significantly higher than those of the control (p<0.05). The present investigation demonstrates that soft gelatin capsules containing water-miscible CoQ10 formulations B (Q-Gel®) and C (Q-Nol?) are superior to powder-filled formulations with regard to their biopharmaceutical characteristics. 相似文献
70.
《Journal of Nuclear Science and Technology》2013,50(12):1056-1062
Mesocarbon microbeads (MCMBs) heat-treated at 1,273 and 3,073 K were irradiated with an electron beam current density ~1.34μA/cm2 of 0.5–1.5 MeV for 0–600 s, and the irradiated MCMBs were examined as anode materials for secondary lithium-ion batteries. Charge capacity of both materials irradiated for short time within 100 s became larger than that before irradiation. Improvement of discharge capacity of MCMB annealed at 3,073 K was achieved by irradiation with 0.5 and 1.5 MeV electrons for 600 s. Good performance of cyclical discharge of MCMB annealed at 3,073 K was also attained by the irradiation with 0.5–1.5 MeV electrons for 600 s. 相似文献