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951.
952.
The effect of crystal structure on the thermal reactivity of CL-20 and its C4-bonded explosives 总被引:1,自引:0,他引:1
Qi-Long Yan Svatopluk Zeman Roman Svoboda Ahmed Elbeih Jiří Málek 《Journal of Thermal Analysis and Calorimetry》2013,112(2):837-849
The critical temperature and mechanism functions for thermal decomposition of ε-CL-20, RS-ε-CL-20, α-CL-20, ε-CL-20/C4, and RS-ε-CL-20/C4 were evaluated based on non-isothermal TG data. A two-step mechanism has been found for thermal decomposition of α-CL-20, ε-CL-20/C4, and RS-ε-CL-20/C4, where the initial step is partly controlled by crystal structure of CL-20. The more reasonable mean activation energies could be obtained after peak separation for each individual steps. In fact, the activation energy for the post integrated process is almost equivalent with that of the second step, indicating that the total activation energy at the main decomposition process is dominated by thermolysis of CL-20 molecular. Besides, it has been found that the decomposition of C4 matrix does not affect the decomposition of normal ε-CL-20, resulting in identical activation energy and reaction model. However, the interaction between the C4 matrix and RS-ε-CL-20 is significant especially at the initial stage, where the activation energy of RS-ε-CL-20/C4 was overestimated before peak separation, while the activation energy for the second step due to thermolysis of CL-20 molecular is underestimated. The first decomposition step for α-CL-20, ε-CL-20/C4, and RS-ε-CL-20/C4 could be considered as autocatalytic process (AC model), whereas the second as JMA model, which is also applicable to that of pure ε-CL-20 and RS-ε-CL-20. Moreover, The critical temperatures of thermal explosion (T b) are obtained as 205.6, 205.5, 209.4, 214.4, and 227.5 °C for α-CL-20, ε-CL-20, RS-ε-CL-20, ε-CL-20/C4, and RS-ε-CL-20/C4, respectively. It proves that the C4 matrix could stabilize ε-CL-20 while the crystal form of CL-20 has little effect on its thermal stability. 相似文献
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Bingjing Ye Huyuan Feng Jihua Zhao Jian Fang Weiguo Shen 《Journal of Thermal Analysis and Calorimetry》2013,111(3):1731-1736
Microcalorimetric techniques had been used to study the influence of different physicochemical parameters on microbial growth in different permafrosts on the Tibetan plateau. The total heat evolution of the permafrost samples amended with glucose, Q T , the values of microbial growth rate constant, k, and the heat output power, P t , were calculated from the power–time (P–t) curves. It is observed that the same coverage vegetation show similar P–t curves, which strongly suggest that the permafrost microorganisms of the homology vegetation coverage have similar structures of community. Furthermore, the vegetation degradation turns out to have significant influence, that is, the better the status of vegetation is, the higher the values of k, CFU and Q T are. 相似文献
954.
Roman Svoboda Pavel Čičmanec Jiří Málek 《Journal of Thermal Analysis and Calorimetry》2013,114(1):285-293
The applicability of the Kissinger equation for the evaluation of apparent activation energy corresponding to glass transition kinetics is examined. Theoretically simulated data based on the generally accepted Tool–Narayanaswamy–Moynihan model were used to represent relevant cases of structural relaxation behavior. The values of the apparent activation energy determined by the Kissinger equation were, despite the linearity of the dependencies, in major disagreement with the original values of ?h * used for the simulation of the source data. Furthermore, a large dependence of the ?h Kis * evaluation (performed using the Kissinger equation) on the thermal history of the glass was found. The latter represents an unacceptable systematic error in the methodology, implying the incorrectness of the Kissinger equation usage for the evaluation of “glass transition activation energy”. This study addresses the currently widespread (incorrect) usage of the Kissinger equation for the above-mentioned purpose. 相似文献
955.
Hui Wang Rui Luo Shijun Liao Julian Key Shan Ji Rongfang Wang 《Journal of Solid State Electrochemistry》2013,17(7):2009-2015
Pt nanoparticles deposited on a low-cost, surfacial, carbonized palygorskite (Pt/C-PLS) prepared by carbonizing sucrose were evaluated as a methanol oxidation catalyst for direct methanol fuel cells. Transmission electron microscopy and Fourier transfrom infrared spectrophotometry analyses revealed that carbon was formed on the surface of PLS and that free silica presented in the C-PLS support. The catalytic activity of methanol oxidation of Pt/C-PLS was higher than that of Pt/C, and the former catalyst had better CO tolerance. 相似文献
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采用简单的热解-硫化两步法成功制备了一种新型的富氮掺杂碳空心纳米笼(NC)负载双元金属硫化物纳米颗粒(CoNixSy)的复合材料 CoNixSy/NC。该策略以丁二酮肟镍为镍源,增加了活性位点,同时前驱体 ZIF-8@Ni-ZIF-67的核壳结构为空心碳纳米笼的构建提供了可能性。这种独特的负载多金属硫化物纳米颗粒的中空结构使CoNixSy/NC作为电极材料时具有更多的活性位点、更高的导电性和结构稳定性,从而使其具有较高的比容量(1 A·g-1时比容量为629.2 F·g-1),优异的循环稳定性(1 A·g-1下1 000次循环测试后容量保持率为93.4%)。当将其进一步组装成对称超级电容器后,在1 A·g-1下可提供207.2 F·g-1的比电容,1 000圈循环稳定后的容量保持率为85.36%。 相似文献