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81.
C. Gontrand A. Merabet S. Krieger-Kaddour C. Dubois J. P. Vallard 《Journal of Electronic Materials》1993,22(1):135-141
The codiffusion of implanted boron and arsenic during rapid thermal annealing in a polysilicon/monocrystalline silicon system
used for high speed bipolar integrated circuit technology has been investigated. Such a process allows a uniformly high concentration
in the emitter regions. It induces a very shallow emitter-base junction depth for an n-p-n transistor. On the contrary, in
p-n-p configuration, when the arsenic dose is lower than the boron dose, boron deeply penetrates the single-crystal silicon,
causing problems for fabricating shallow junctions. The rapid thermal annealing-induced redistribution of arsenic and boron
implanted at various implant doses in a 380 nm low-pressure chemical vapor deposition (LPCVD) polysilicon layer has been studied
by secondary ion mass spectroscopy measurements. A strong lowering of the minority dopant diffusion in the polysilicon film
is observed due to the high concentration of the other dopant. This effect is mainly related to grain boundary trap saturation
while the electric field issued from dopant activation in the fastly recrystallized amorphous layer due to arsenic implantation
in the upper region of the LPCVD film has a lesser effect. Transmission electron microscopy measurements show that recrystallization
extends deeper than the amorphous layer, which is responsible for the increase of grain size. Sheet resistance measurements
have been performed as an approach to the electrical behavior for these structures. 相似文献
82.
83.
Soroosh Sharifi‐Asl Fernando A. Soto Tara Foroozan Mohammad Asadi Yifei Yuan Ramasubramonian Deivanayagam Ramin Rojaee Boao Song Xuanxuan Bi Khalil Amine Jun Lu Amin Salehi‐khojin Perla B. Balbuena Reza Shahbazian‐Yassar 《Advanced functional materials》2019,29(23)
LiCoO2 is a prime example of widely used cathodes that suffer from the structural/thermal instability issues that lead to the release of their lattice oxygen under nonequilibrium conditions and safety concerns in Li‐ion batteries. Here, it is shown that an atomically thin layer of reduced graphene oxide can suppress oxygen release from LixCoO2 particles and improve their structural stability. Electrochemical cycling, differential electrochemical mass spectroscopy, differential scanning calorimetry, and in situ heating transmission electron microscopy are performed to characterize the effectiveness of the graphene‐coating on the abusive tolerance of LixCoO2. Electrochemical cycling mass spectroscopy results suggest that oxygen release is hindered at high cutoff voltage cycling when the cathode is coated with reduced graphene oxide. Thermal analysis, in situ heating transmission electron microscopy, and electron energy loss spectroscopy results show that the reduction of Co species from the graphene‐coated samples is delayed when compared with bare cathodes. Finally, density functional theory and ab initio molecular dynamics calculations show that the rGO layers could suppress O2 formation more effectively due to the strong C? Ocathode bond formation at the interface of rGO/LCO where low coordination oxygens exist. This investigation uncovers a reliable approach for hindering the oxygen release reaction and improving the thermal stability of battery cathodes. 相似文献
84.
用透射电子显微镜(TEM)和X射线双晶衍射仪(DCXRD)对在Si(111)衬底上生长的InGaN/GaN多量子阱(MQW)LED外延材料的微结构进行了观察和分析.从TEM高分辨像观察到,在Si和AlN界面处未形成SixNy非晶层,在GaN/AlN界面附近的GaN上有堆垛层错存在,多量子阱的阱(InGaN)和垒(GaN)界面明锐、厚度均匀;TEM和DCXRD进一步分析表明MQW附近n型GaN的位错密度为10acm-2量级,其中多数为b=1/3〈112-0〉的刃位错. 相似文献
85.
用透射电子显微镜对Si衬底生长GaN/InGaN多量子阱材料进行横断面测试,在衬底和缓冲层区域进行高分辨电子显微成像(HRTEM)、电子衍射衬度成像、选区电子衍射成像,在量子阱附近区域进行了双束近似电子衍衬像对其位错特性进行研究;用场发射扫描电子显微镜对饱和KoH溶液腐蚀前后材料成像.结果发现,AIN缓冲层具有多孔结构,高温GaN层位错平均密度达108cm-2,同扫描电子显微镜得到的六角腐蚀坑密度一致,量子阱以下发现大量位错发生90°弯曲,而使穿过量子阱位错密度大大降低.在线位错中,以刃位错居多,其次是混合位错,所观察区域几乎未见螺位错. 相似文献
86.
采用高温热解法 ,以二茂铁 乙二胺有机溶剂为前驱液制备CNx 纳米管过程中 ,改变前驱液配比 ,对 86 0℃ ,不同二茂铁含量条件下制备出的CNx 纳米管进行了产量统计、形貌结构观察和拉曼光谱研究。结果显示 :随着前躯液中二茂铁含量的相对增大 ,不但CNx 纳米管产量随之增加 ,而且产物中“竹节状”结构纳米管相对“中空”结构纳米管的比重也增大 ;拉曼光谱结果进一步证实了由于“竹节状”结构CNx 纳米管的含量或比重增加所带来的纳米管样品整体或平均含氮量的升高而导致的样品结晶有序程度的降低。对单独钴粉和二茂铁催化条件下生成CNx 纳米管的形貌观察进一步证实 :二茂铁在热解法制备“竹节状”结构CNx 纳米管过程中的浮动催化作用显著 ,有利于实现含氮量较高、结构均匀的CNx 纳米管的可控制生长。 相似文献
87.
The age-hardenable Ti–5Fe–5Zr (wt. %, 5Zr) alloy has been consolidated by pulsed electric current sintering, following a β solution treatment, and the results are compared with a Ti–5Fe (0Zr) alloy. The precipitation sequence measured at 640°C ageing is β?+?athermal ω?→?β?+?isothermal ω?→?β?+?α. At the peak hardness isothermal ω phase forms at 20?s of ageing. The Zr addition retards the precipitation kinetics of the α phase; as a result, the α phase nucleates at latest at 300?s ageing in the overaged state. Fe is partitioned into β, while it is depleted from the α phases. There is Zr enrichment near the α/β interface when the α phase precipitates due to a solute drag effect; the growth rate of the α phase in the 5Zr alloy is significantly reduced compared with that in the 0Zr alloy. 相似文献
88.
89.
本文采用高分辨透射电子显微技术对在Si衬底生长的GaN基多量子阱外延材料的位错特征、外延层与衬底的晶体取向关系及界面的结晶形态等微观结构进行了分析和研究.结果表明:Si衬底生长的GaN与衬底有一定的取向关系;材料在MQW附近的穿透位错密度达108 cm-2量级,且多数为刃型位错;样品A的多量子阱下方可见平行于界面方向的... 相似文献
90.
Changzhen Wang Steve Tobin Themis Parodos David J. Smith 《Journal of Electronic Materials》2006,35(6):1192-1196
The microstructure of p-n device structures grown by liquid-phase epitaxy (LPE) on CdZnTe substrates has been evaluated using
transmission electron microscopy (TEM). The devices consisted of thick (∼21-μm) n-type layers and thin (∼1.6-μm) p-type layers,
with final CdTe (∼0.5 μm) passivation layers. Initial observations revealed small defects, both within the n-type layer (doped
with 8×1014/cm3 of In) and also within the p-type layer but at a much reduced level. These defects were not visible, however, in cross-sectional
samples prepared by ion milling with the sample held at liquid nitrogen temperature. Only isolated growth defects were observed
in samples having low indium doping levels (2×1014/cm3). The CdTe passivation layers were generally columnar and polycrystalline, and interfaces with the p-type HgCdTe layers were
uneven. No obvious structural changes were apparent in the region of the CdTe/HgCdTe interfaces as a result of annealing at
250°C. 相似文献