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61.
甲醇与碳酸二甲酯共沸液的分离研究进展 总被引:8,自引:0,他引:8
综述了DMC-CH_3OH二元共沸液的各种分离方法。讨论了共沸精馏和萃取精馏的工艺流程。 相似文献
62.
63.
通过对制冷压缩机功耗的模拟和对实际运行数据的分析,比较了乙烯装置中的复迭多级制冷系统和混合冷剂制冷系统的用能状况,分析了混合冷剂制冷的优点和不足。采用AspenPlus10.2软件模拟的结果表明,采用混合冷剂制冷技术的丙烯-混合冷剂复迭制冷系统比传统的丙烯-乙烯复迭制冷系统节省功耗4.3GJ/h,制冷压缩机损系数则从47.6%减小到43.3%,而系统效率由25.0%提高到26.6%。虽混合冷剂在换热过程中出现的气液两相流,会在一定程度上抵消其在热力学效率上的优势,但混合制冷技术用于乙烯装置仍可降低能耗、提高热力学效率。 相似文献
64.
聚乙烯接枝改性及其与铝的粘结性 总被引:8,自引:0,他引:8
聚乙烯在过氧化二异丙苯存在下分别与丙烯酸,顺丁烯酸酐,顺丁烯二酸,顺丁烯二酸钠,丙烯酸羧丙酯,甲基丙烯酸环丙酯等单体熔融挤出,产物的红外光谱表明聚乙烯不同程度地接了各种极性基团。 相似文献
65.
本文采用了与常规(容量法)相反的方法测定球铁中的镁,并克服了其它方法的弊端,进一步找到了在工业上分析镁的适宜条件。 相似文献
66.
María Jos García Carlos Lucena Francisco Javier Romera 《International journal of molecular sciences》2021,22(9)
Iron (Fe) and phosphorus (P) are two essential elements for plant growth. Both elements are abundant in soils but with poor availability for plants, which favor their acquisition by developing morphological and physiological responses in their roots. Although the regulation of the genes related to these responses is not totally known, ethylene (ET) and nitric oxide (NO) have been involved in the activation of both Fe-related and P-related genes. The common involvement of ET and NO suggests that they must act in conjunction with other specific signals, more closely related to each deficiency. Among the specific signals involved in the regulation of Fe- or P-related genes have been proposed Fe-peptides (or Fe ion itself) and microRNAs, like miR399 (P), moving through the phloem. These Fe- or P-related phloem signals could interact with ET/NO and confer specificity to the responses to each deficiency, avoiding the induction of the specific responses when ET/NO increase due to other nutrient deficiencies or stresses. Besides the specificity conferred by these signals, ET itself could confer specificity to the responses to Fe- or P-deficiency by acting through different signaling pathways in each case. Given the above considerations, there are preliminary results suggesting that ET could regulate different nutrient responses by acting both in conjunction with other signals and through different signaling pathways. Because of the close relationship among these two elements, a better knowledge of the physiological and molecular basis of their interaction is necessary to improve their nutrition and to avoid the problems associated with their misuse. As examples of this interaction, it is known that Fe chlorosis can be induced, under certain circumstances, by a P over- fertilization. On the other hand, Fe oxides can have a role in the immobilization of P in soils. Qualitative and quantitative assessment of the dynamic of known Fe- and P-related genes expression, selected ad hoc and involved in each of these deficiencies, would allow us to get a profound knowledge of the processes that regulate the responses to both deficiencies. The better knowledge of the regulation by ET of the responses to these deficiencies is necessary to properly understand the interactions between Fe and P. This will allow the obtention of more efficient varieties in the absorption of P and Fe, and the use of more rational management techniques for P and Fe fertilization. This will contribute to minimize the environmental impacts caused by the use of P and Fe fertilizers (Fe chelates) in agriculture and to adjust the costs for farmers, due to the high prices and/or scarcity of Fe and P fertilizers. This review aims to summarize the latest advances in the knowledge about Fe and P deficiency responses, analyzing the similarities and differences among them and considering the interactions among their main regulators, including some hormones (ethylene) and signaling substances (NO and GSNO) as well as other P- and Fe-related signals. 相似文献
67.
Hormone signaling plays a pivotal role in plant–microbe interactions. There are three major phytohormones in plant defense: salicylic acid (SA), jasmonic acid (JA), and ethylene (ET). The activation and trade-off of signaling between these three hormones likely determines the strength of plant defense in response to pathogens. Here, we describe the allocation of hormonal signaling in Brassica napus against the fungal pathogen Leptosphaeria maculans. Three B. napus genotypes (Westar, Surpass400, and 01-23-2-1) were inoculated with two L. maculans isolates (H75 8-1 and H77 7-2), subsequently exhibiting three levels of resistance: susceptible, intermediate, and resistant. Quantitative analyses suggest that the early activation of some SA-responsive genes, including WRKY70 and NPR1, contribute to an effective defense against L. maculans. The co-expression among factors responding to SA/ET/JA was also observed in the late stage of infection. The results of conjugated SA measurement also support that early SA activation plays a crucial role in durable resistance. Our results demonstrate the relationship between the onset patterns of certain hormone regulators and the effectiveness of the defense of B. napus against L. maculans. 相似文献
68.
在反应温度为45~75℃,NY 健化剂浓度为0.093mol/L,水比为6~10的反应条件下,对均相催化水合法合成乙二醇动力学进行了研究。测定了反应速率常数及反应过程中溶液 pH 值的变化。依据实验结果,提出了反应机理,建立了反应动力学方程,并利用 Levenberg-Marquardt 方法回归了动力学参数。研究结果表明:在 NY 催化剂存在下,均相催化水合法合成乙二醇反应对环氧乙烷浓度是一级反应,其表观活化能为71113.8 J/mol 和指前因子3.05×10~9 min~(-1)。相对直接水合法而言,NY 催化剂降低了反应的活化能,大大提高了反应速度。 相似文献
69.
Synthesis of Dimethyl Carbonate from Methanol and Carbon dioxide using Potassium Methoxide as Catalyst under Mild Conditions 总被引:2,自引:0,他引:2
Pd-supported on WO3–ZrO2 (W/Zr atomic ratio=0.2) calcined at 1073 K was found to be highly active and selective for gas-phase oxidation of ethylene to acetic acid in the presence of water at 423 K and 0.6 MPa. Contact time dependence demonstrated that acetic acid is formed via acetaldehyde formed by a Wacker-type reaction, not through ethanol by hydration of ethylene. 相似文献
70.
The solubility parameter of poly(ethylene oxide) at 25°C has been determined using the method developed by DiPaola-Baranyi and Guillet, by the extrapolation of the values of the interaction parameter χ, at high temperatures, ranging from 70°–90°, 90°–110° and 110°–130°C down to 25°C. The values of the solubility parameter obtained, depending on the temperature ranges employed, are 9.8, 9.9 and 10.1, respectively. 相似文献