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991.
将TiNb2O7的前驱体在不同温度(400℃、800℃、900℃、1000℃和1100℃)煅烧,用固相合成法制备TiNb2O7负极材料并对其样品进行了TG-DSC、XRD和SEM表征和电化学性能测试。结果表明:在900℃煅烧前驱体,锐钛矿与Nb2O5反应的主要产物为Ti2Nb10O29。Ti2Nb10O29与金红石反应生成了TiNb2O7,生成纯单斜相TiNb2O7的最佳条件为在1100℃煅烧6 h。TiNb2O7负极材料在0.2C电流密度时初始容量为278.4 mAh/g,初始库伦效率为82.9%。TiNb2O7具有良好的倍率容量,在1C循环100次后容量保持率为89%。 相似文献
992.
Weihua Chen Xixue Zhang Liwei Mi Chuntai Liu Jianmin Zhang Shizhong Cui Xiangming Feng Yuliang Cao Changyu Shen 《Advanced materials (Deerfield Beach, Fla.)》2019,31(8)
Sodium‐ion batteries (SIBs) have gained tremendous interest for grid scale energy storage system and power energy batteries. However, the current researches of anode for SIBs still face the critical issues of low areal capacity, limited cycle life, and low initial coulombic efficiency for practical application perspective. To solve this issue, a kind of hierarchical 3D carbon‐networks/Fe7S8/graphene (CFG) is designed and synthesized as freestanding anode, which is constructed with Fe7S8 microparticles well‐welded on 3D‐crosslinked carbon‐networks and embedded in highly conductive graphene film, via a facile and scalable synthetic method. The as‐prepared freestanding electrode CFG represents high areal capacity (2.12 mAh cm?2 at 0.25 mA cm?2) and excellent cycle stability of 5000 cycles (0.0095% capacity decay per cycle). The assembled all‐flexible sodium‐ion battery delivers remarkable performance (high areal capacity of 1.42 mAh cm?2 at 0.3 mA cm?2 and superior energy density of 144 Wh kg?1), which are very close to the requirement of practical application. This work not only enlightens the material design and electrode engineering, but also provides a new kind of freestanding high energy density anode with great potential application prospective for SIBs. 相似文献
993.
Graphene, a star 2D material, has attracted much attention because of its unique properties including linear electronic dispersion, massless carriers, and ultrahigh carrier mobility (104–105 cm2 V?1 s?1). However, its zero bandgap greatly impedes its application in the semiconductor industry. Opening the zero bandgap has become an unresolved worldwide problem. Here, a novel and stable 2D Ruddlesden–Popper‐type layered chalcogenide perovskite semiconductor Ca3Sn2S7 is found based on first‐principles GW calculations, which exhibits excellent electronic, optical, and transport properties, as well as soft and isotropic mechanical characteristics. Surprisingly, it has a graphene‐like linear electronic dispersion, small carrier effective mass (0.04 m0), ultrahigh room‐temperature carrier mobility (6.7 × 104 cm2 V?1 s?1), Fermi velocity (3 × 105 m s?1), and optical absorption coefficient (105 cm?1). Particularly, it has a direct quasi‐particle bandgap of 0.5 eV, which realizes the dream of opening the graphene bandgap in a new way. These results guarantee its application in infrared optoelectronic and high‐speed electronic devices. 相似文献
994.
995.
Haorui Shen Fulai Qi Hucheng Li Pei Tang Xuning Gao Shan Yang Zichen Hu Zhuangnan Li Jun Tan Shuo Bai Feng Li 《Advanced functional materials》2021,31(48):2103309
Lithium dendrites caused by nonuniform Li+ flux leads to the capacity fade and short-circuit hazard of lithium metal batteries. The solid electrolyte interface (SEI) is critical to the uniformity of Li+ flux. Here, an ultrafast preparation of uniform and vertical Cu7S4 nano-flake arrays (Cu7S4 NFAs) on the Cu substrate is reported. These arrays can largely improve the lithiophilicity of the anode and form Li2S-enriched SEI due to the electrochemical reduction of Cu7S4 NFAs with lithium. A further statistical analysis suggests that the SEI, with a higher content of Li2S, is more effective to inhibit the formation of lithium dendrites and yields less dead lithium. A quite stable coulombic efficiency of 98.6% can be maintained for 400 cycles at 1 mA cm–2. Furthermore, at negative to positive electrode capacity ratio of 1.5 (N/P = 1.5), the full battery of Li@Cu7S4 NFAs||S shows 83% capacity retention after 100 cycles at 1 C, much higher than that of Li@Cu||S (33%). The findings demonstrate that high Li2S content in the SEI is crucial for the dendrite inhibition to achieve better electrochemical performance. 相似文献
996.
The effect of temperature on product formation during the sulphonation of indigo with concentrated sulphuric acid and 30 % fuming sulphuric acid was studied with the aid of high performance liquid chromatographic (HPLC) analysis. Trisulphoindigo was prepared by the sulphonation of indigo with concentrated sulphuric acid at 160°C. The di- and tetra-sulphoindigo side products formed during the reaction were removed by preparative HPLC to yield a product of high chromatographic purity. The trisulphoindigo content of the food dye FD & C Blue No. 2 and the purity of commercially available trisulphoindigo were determined by HPLC analysis. 相似文献
997.
Lipids of canola seedcoats (Brassica napus L. andB. rapa L.) were prepared by surface washing and by complete extraction of seed coats with toluene. The major fatty acyl-containing
triacylglycerols, wax esters and free fatty acids were separated by thin-layer chromatography prior to transesterification
and analysis by gas-liquid chromatography. The proportion of C18∶1n−7 to C18∶1n−9 was higher in the extracted lipids than
in the surface-washed lipids for all three classes. 相似文献
998.
重要的半合成头孢菌素中间体--7-ADCA 总被引:4,自引:0,他引:4
7-氨基-3-去乙酰氧基头孢烷酸(7-ADCA)是以青霉素G为原料,经氧化、扩环重排、裂解3步反应制得.目前用于裂解反应的固定化酰化酶技术日益成熟,因而化学法裂解的生产工艺已逐渐被淘汰.世界上主要生产厂家有荷兰GIST公司、美国TEVA公司、意大利DOBFA公司、台湾骏祥公司和印度LUPIN公司等.国内华北制药倍达公司开发了酶法生产7-ADCA的工艺,并建立了250t/a的生产能力,产品质量与进口产品相当.我国7-AD-CA年需求量约900t,而生产能力不足300t/a.国内企业应改进回收工艺、降低生产成本、实现规模化生产,以改变市场依赖进口的局面. 相似文献
999.
以4-氟-2-硝基甲苯为原料,经聚合、还原、缩合得到标题化合物,总收率20.3%。该方法步骤少、操作简便、收率较高,具有工业应用价值。 相似文献
1000.
In contrast to previous claims, the addition of niobia to catalysts containing vanadia supported on titania resulted in much enhanced activity for low-temperature SCR of NO with NH3 only at low vanadia loadings. Niobia promoted catalysts could also be demonstrated to show higher selectivities to N2, especially at high temperatures and low vanadia loading. This enhancement of the activity cannot be explained only on the basis of the observation that niobia stabilized the surface area of the catalyst: calculations of the activation energy suggest that a different mechanism of the reaction may be at work at low vanadia loadings. 相似文献