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41.
42.
PBAMO的非等温结晶行为研究 总被引:1,自引:1,他引:0
用差示扫描量热仪(DSC)研究了聚3,3-二叠氮甲基氧杂丁环(PBAMO)在匀速降温过程中的结晶行为,结晶峰峰顶温度随降温速率的变化符合一阶指数衰减规律,结晶度在降温速率为2 ℃·min-1时达到最大,降温速率为5 ℃·min-1时,结晶速率达到最大.用Ozawa公式研究了非等温结晶行为,得到的Ozawa指数随温度的升高而增大,分为三个区域: (1) 温度小于14 ℃,Ozawa指数小于3; (2) 温度介于14~18 ℃,Ozawa指数介于3~4.12; (3) 温度高于18 ℃,Ozawa指数接近5.根据Kissinger公式计算得到的结晶活化能为59.37 kJ·mol-1. 相似文献
43.
从恒速升温速率下的DSC曲线峰温计算含能材料放热分解反应动力学参数的理论和数值方法(英) 总被引:2,自引:1,他引:1
根据Kooij公式和van't Hoff公式,从恒速升温速率下的DSC曲线峰温导出了计算含能材料放热分解反应动力学参数的两个数学表达式,提出了计算相应动力学参数的数值方法.对1,3,5-三硝基-1,3,5-三氮杂环己酮-2(Keto-RDX),由导出的两个表达式、Kissinger法、Ozawa法、Tang法、Hu-Gao-Zhang法、非线性等转化率积分法(NL-INT)所得的活化能E值彼此接近,表明Kooij's公式中的a值取0.5,van't Hoff公式的b值取0.003,可得到合理的动力学参数. 相似文献
44.
探讨D-柠檬烯(D-limonene)对大鼠酒精性肝损伤脂质代谢紊乱的保护作用及可能作用机制,利用持续酒精灌胃的方法建立大鼠酒精肝损伤模型,分为A、B、C、D、E、F、G共7 组。A组为空白对照组,每日给予蒸馏水灌胃,前2 周8 mL/(kg·d),后4 周12 mL/(kg·d);B组为酒精模型组,每日灌胃体积分数为50%的乙醇,前2 周8 mL/(kg·d),后4 周12 mL/(kg·d);C、D、E组分别为D-柠檬烯低、中、高剂量组,每日分别灌胃D-柠檬烯100、200、400 mL/(kg·d),其中D-柠檬烯与A、B组等量的50%的乙醇混合后灌胃;F组为水和D-柠檬烯空白高剂量组,每日给予D-柠檬烯400 mL/(kg·d);G组为甘利欣药物对照组,灌胃量200 mL/(kg·d)。HE染色和电镜观察肝组织形态结构和肝组织超微结构的变化,测定血清谷丙转氨酶(alanine transaminase,ALT)、谷草转氨酶(aspartate transaminase,AST)、碱性磷酸酶(phosoporic acid,ALP)、胆碱酯酶(cholinesterase,CHE)、甘油三酯(triglyceride,TG)、胆固醇(cholesterol,CHO)、低密度脂蛋白胆固醇(low densitylipoprotein-cholesterol,LDL-C)水平。结果电镜下观察到A组肝细胞结构正常,核呈圆形或椭圆,线粒体形态正常。B组肝细胞次级溶酶体数量增加,线粒体形状不规则,脂滴多。C组可见少量脂滴,高尔基体正常,线粒体清楚。D组少量脂滴,胆小管有内容物,线粒体正常。E组线粒体高尔基体正常,少量脂滴,核圆。F组细胞器无异常,少量脂滴。G组少量脂滴,偶见溶酶,体线粒体正常。B组大鼠血清ALT、AST、ALP、CHE、TG、CHO、LDL-C均高于空白对照组,差异显著(P<0.05);F组大鼠血清所测各指标与空白对照组无明显差异;而D-柠檬烯低、中、高剂量干预组和酒精模型组比较,血清所测各指标水平均有不同程度地降低,其中D-柠檬烯中、高剂量干预组血清所测各指标水平明显低于酒精模型组,差异显著(P<0.05)。结论:过量酒精摄入引起的肝组织超微结构病理损伤与升高血清ALP、CHE、ALT、AST、TG、CHO、LDL-C水平,在D-柠檬烯干预下有所减轻和降低。因此,D-柠檬烯可调节过量酒精摄入造成的脂质代谢紊乱。 相似文献
45.
46.
在热红外光谱区域,假设非同温平面混合像元的发射率为r-emissivity,那么它的辐射温度是随波长变化的.以典型的由土壤和植被组成的非同温平面混合像元为例,分析了非同温对其辐射温度的影响,并给出体现辐射温度变化的可能的方法.利用模拟的热红外高光谱数据对该方法进行了验证,验证结果表明,该方法能够较好地刻画非同温平面混合像元辐射温度随波长的变化,提高了非同温平面混合像元r-emissivity的反演精度. 相似文献
47.
Zenon Sarbak 《Catalysis Today》2001,65(2-4):293-299
In the search for the active catalysts of hydrodesulfurization reaction, an attempt was made to use zeolites as supports. A series of NaLaX, Mo/NaLaX and NiMo/NaLaX as well as NaLaY, Mo/NaLaY and NiMo/NaLaY catalysts was prepared and their performance in this reaction was studied. It was shown that crystalline structure of the lanthana forms of the above zeolites only little collapsed after ion-exchange and impregnation with active Mo and NiMo components. The NiMo catalysts supported on the zeolites studied were found active in thiophene hydrodesulfurization. The catalysts with lanthana after the first step of ion exchange were the most active. 相似文献
48.
The energy consumption during dewatering and carboxyl concentrations on the surfaces of six different coals were examined. Three stages of dewatering were investigated based on the energy consumption. The water in the spaces between coal particles and large pores, water in progressively smaller capillaries and pores, water clusters around the functional groups, and water directly absorbed by oxygen functional groups were subsequently removed with increasing energy consumption. The moisture present in three forms was significantly affected by carboxyl concentrations. In the first and second stages, the energy consumption at the same residual moisture content was closely related to the carboxyl concentrations. Even at the same ratio of moisture content to carboxyl concentration, energy consumption increased with an increase in carboxyl concentration on coal surface in the second stage. 相似文献
49.
《国际聚合物材料杂志》2012,61(6):322-335
Thermal degradation kinetics of solid-state D-sucrose and D-glucose were studied using differential thermal analysis (DTA) and thermogravimetric analysis (TGA) techniques. The melting and decomposition process of the two sugars were displayed as endothermic peaks on the DTA curve under nonisothermal conditions. It was noticed that the melting peak temperature of D-glucose was lower than that of the other sugar. For the decomposition processes, the opposite occurred. The decomposition kinetic parameters, such as the decomposition activation energy (Ed) and the frequency factor (Ko), were calculated by employing different approximations. The relative stability of the studied sugars was determined. Molecular mechanics (MM) calculations showed that the optimal geometric structure (OMG) of D-sucrose was at least three orders of magnitude more stable than the molecular geometric (MG) structure. These calculations indicate that the potential energy (PE (kcal mol?1)) of the OMG is about three (1.142 × 103) orders of magnitude lower than the MG structure of the same sugar. So, optimizing the geometry of the molecular structure (OMG) is very important for understanding the stability of this sugar. 相似文献
50.
Non-isothermal TG/DTG measurements are widely used to determine kinetic parameters of oxidation and gasification of carbons, e.g. by multi-heating rate methods. Thereby it is important to avoid spurious effects due to diffusion limitations. In this work, TG/DTG experiments with activated carbon were conducted under isothermal and non-isothermal conditions. The agreement of the experimental results with results of simulations based on the intrinsic kinetics, pore diffusion and external diffusion in/to the sample (crucible) is very good. The simulations show that mass transfer has an unwanted influence on TG measurements, if the concentration of the gaseous reactant (O2 and CO2) is too low and/or the heating rate is too high. Based on literature data, the simulation was extended to blast furnace coke with a very low reactivity and to highly reactive coke from pyrolysis of miscanthussinensis. The simulations and theoretical considerations lead to a criterion to exclude the influence of mass transfer on TG measurements a priori. This criterion is valid for combustion as well as for gasification with steam or carbon dioxide. 相似文献