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891.
Zhenglong Yang Kangyu Fu Jing Yu Peiting Zhou Zhihao Cheng 《Journal of fluorescence》2018,28(4):905-911
A colorimetric and fluorescent indicator based on cinnamamide group-containing rhodamine derivative was synthesized for the detection of Hg2+. The rhodamine B and cinnamamide were connected via ethylenediamine as a bridging molecule through a condensation reaction to obtain a colorimetric and fluorescent indicator for the detection of Hg2+ in H2O-EtOH (4:1, v/v). The indicator was excellent in the selectivity of Hg2+ and was almost unaffected by other common ions such as Na+, K+, Mg2+, Fe3+, Cu2+, Zn2+, Cr3+. The Hg2+-containing aqueous solution turned from colorless to red within 7 min after the addition of the indicator, and had an absorption peak at 564 nm in UV-vis, which implies a significant colorimetric phenomenon. Their characteristic peaks varied with the Hg2+ content, and they reached a linear relationship at low concentrations. The binding stoichiometry proved to be 1:1. The lowest detection limit was 4.1?×?10?7 mol/L, ranging from acidic to neutral. 相似文献
892.
本文基于第一性原理方法研究了Y,Zr,Nb在Sn位掺杂SnO_2的键长变化、稳定性、能带结构以及态密度.结果表明:Y,Zr,Nb在Sn位掺杂SnO_2使附近的键长发生改变,改变量最大是Y掺杂SnO_2体系;掺杂体系的杂质替换能都为负值,表明体系为稳定结构;掺杂使SnO_2能级增多,能较好的调节带隙值;而Y掺杂SnO_2体系价带顶端有一条能级越过了费米线表明该体系呈现出半导体的特征;同时,Y,Zr,Nb掺杂SnO_2使导带底端的能级出现分离;在低能区的态密度仍主要由Sn、O的s轨道贡献;在高能区态密度的掺杂体系出现sp杂化的现象; Zr掺杂SnO_2的态密度能量向低能区移动. 相似文献
893.
研制了一套能够同时测量线缆皮线和芯线感应电流的试验系统,研究自然闪电条件下敷地线缆的耦合问题。结果表明:不同位置处的线缆皮线感应电流波形基本一致,但幅值存在一定差异,说明感应电流空间分布不均匀; 所测线缆芯线和皮线感应电流的时域波形和频谱比较相似,能量集中在1 kHz~1 MHz之间; 正负地闪芯线感应电压波形均为单一脉冲型,波形持续时间10~49 μs; 正地闪线缆感应电压的幅值范围及幅值平均值都大于负地闪相应结果,说明正地闪产生的线缆耦合作用大于负地闪; 不同雷电过程的线缆感应电压幅值与磁感应强度有较小的相关性,而同一雷电过程则基本成线性关系; 正地闪线缆感应电压波形持续时间、半峰值宽度、10%~90%上升时间的范围及均值都比负地闪的要大。 相似文献
894.
MgB_2材料具备临界转变温度较高、相干长度大、临界电流和临界磁场高等优点,被认为有替代Nb基超导材料的潜力.研究了不同温度下以化学气相沉积法制备的硼(B)薄膜的微观结构.实验结果表明:较低温度沉积的B先驱薄膜为无定形B膜,可以与Mg蒸气反应生成MgB_2超导薄膜;当沉积温度高于550?C时,所得硼薄膜为晶型薄膜;以晶型硼薄膜为先驱膜在镁蒸气中退火,不能生成硼化镁超导薄膜.利用晶型B膜的这一特点,成功制备了以晶型硼薄膜为介质层的硼化镁超导约瑟夫森结. 相似文献
895.
Excited‐state hydrogen bond strengthening of coumarin 153 in ethanol solvent: a TDDFT study 下载免费PDF全文
Jinmei Xu Junsheng Chen Shunle Dong Aiping Fu Hongliang Li Tianshu Chu 《Journal of Physical Organic Chemistry》2016,29(6):305-311
So far, coumarin dyes have been extensively studied with various means to understand their photophysical behaviors and photochemical properties. Here, our performing time‐dependent density functional theory calculation is aimed at exploring the excited‐state hydrogen bonding dynamics of coumarin 153 (C153) in protic ethanol (EtOH) solvent. The calculated results suggest that the excited‐state hydrogen bond C?O?H?O between C?O group and O?H group in the C153‐EtOH complex is strengthened, and the S0 → S1 transition of the complex corresponds to the highest occupied molecular orbital (HOMO) hopping to the lowest unoccupied molecular orbital (LUMO). The excited‐state hydrogen bond strengthening has been further confirmed by its larger binding energy in the S1 state than in the S0 state. In addition, because of the formation of the hydrogen bond C?O?H?O, a red shift of about 7 nm occurs in the electronic spectra of the C153‐EtOH complex, which is in good accordance with the experiment result. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
896.
WeiPing Liu ZhiHong Li JiangJun He XiaoDong Tang Gang Lian Zhu An JianJun Chang Han Chen QingHao Chen XiongJun Chen ZhiJun Chen BaoQun Cui XianChao Du ChangBo Fu Lin Gan Bing Guo GuoZhu He Alexander Heger SuQing Hou HanXiong Huang Ning Huang BaoLu Jia LiYang Jiang Shigeru Kubono JianMin Li KuoAng Li Tao Li YunJu Li Maria Lugaro XiaoBing Luo HongYi Ma ShaoBo Ma DongMing Mei YongZhong Qian JiuChang Qin Jie Ren YangPing Shen Jun Su LiangTing Sun WanPeng Tan Isao Tanihata Shuo Wang Peng Wang YouBao Wang Qi Wu ShiWei Xu ShengQuan Yan LiTao Yang Yao Yang XiangQing Yu Qian Yue Sheng Zeng HuanYu Zhang Hui Zhang LiYong Zhang NingTao Zhang QiWei Zhang Tao Zhang XiaoPeng Zhang XueZhen Zhang ZiMing Zhang Wei Zhao Zuo Zhao Chao Zhou JUNA Collaboration 《中国科学:物理学 力学 天文学(英文版)》2016,59(4):642001
Jinping Underground laboratory for Nuclear Astrophysics(JUNA) will take the advantage of the ultra-low background of CJPL lab and high current accelerator based on an ECR source and a highly sensitive detector to directly study for the first time a number of crucial reactions occurring at their relevant stellar energies during the evolution of hydrostatic stars. In its first phase, JUNA aims at the direct measurements of~(25)Mg(p,γ)~(26)Al,~(19)F(p,α)~(16)O,~(13)C(α,n)~(16)O and ~(12)C(α,γ)~(16)O reactions. The experimental setup,which includes an accelerator system with high stability and high intensity, a detector system, and a shielding material with low background, will be established during the above research. The current progress of JUNA will be given. 相似文献
897.
We describe in this paper the synthesis and the characterization of Li4Ti5O12-reduced graphene oxide (LTO-RGO) composite and demonstrate their use as hybrid supercapacitor, which is consist of an LTO negative electrode and activate carbon (AC) positive electrode. The LTO-RGO composites were synthesized using a simple, one-step process, in which lithium sources and titanium sources were dissolved in a graphene oxide (GO) suspension and then thermal treated in N2. The lithium-ion battery with LTO-RGO composite anode electrode revealed higher discharge capacity (167 mAh g?1 at 0.2 C) and better capacity retention (67%) than the one with pure LTO. Meanwhile, compared with the AC//LTO supercapacitor, the AC//LTO-RGO hybrid supercapacitor exhibits higher energy density and power density. Results show that the LTO-RGO composite is a very promising anode material for hybrid supercapacitor. 相似文献
898.
Han Fu K. V. Reich B. I. Shklovskii 《Journal of Experimental and Theoretical Physics》2016,122(3):456-471
This mini-review is dedicated to the 85th birthday of Prof. L.V. Keldysh, from whom we have learned so much. In this paper, we study the potential and electron density depth profiles in surface accumulation layers in crystals with a large and nonlinear dielectric response such as SrTiO3 (STO) in the cases of planar, spherical, and cylindrical geometries. The electron gas can be created by applying an induction D0 to the STO surface. We describe the lattice dielectric response of STO using the Landau–Ginzburg free energy expansion and employ the Thomas–Fermi (TF) approximation for the electron gas. For the planar geometry, we arrive at the electron density profile n(x) ∝ (x + d)–12/7, where d ∝ D0–12/7. We extend our results to overlapping electron gases in GTO/STO/GTO heterojunctions and electron gases created by spill-out from NSTO (heavily n-type doped STO) layers into STO. Generalization of our approach to a spherical donor cluster creating a big TF atom with electrons in STO brings us to the problem of supercharged nuclei. It is known that for an atom with a nuclear charge Ze where Z > 170, electrons collapse onto the nucleus, resulting in a net charge Zn < Z. Here, instead of relativistic physics, the collapse is caused by the nonlinear dielectric response. Electrons collapse into the charged spherical donor cluster with radius R when its total charge number Z exceeds the critical value Zc ≈ R/a, where a is the lattice constant. The net charge eZn grows with Z until Z exceeds Z* ≈ (R/a)9/7. After this point, the charge number of the compact core Zn remains ≈ Z*, with the rest Z* electrons forming a sparse TF atom with it. We extend our studies of collapse to the case of long cylindrical clusters as well. 相似文献
899.
Carbon black (N234) and silica (Vulksail N) with a silane coupling agent Si-69 were chosen as reinforcing fillers in butyl rubber (IIR). The rheological behavior of the IIR compounds and the dynamic mechanical properties of IIR vulcanizates were investigated with a rubber processing analyzer and dynamic mechanical analysis (DMA) to examine the filler dispersion in the rubber matrix and the interaction between filler and matrix. The data indicated that the N234 filled IIR compounds had more filler networks than those filled with silica. Filler networks first appeared at 30 phr N234 and 45 phr silica with silane coupling agent Si-69. The interaction between N234 and IIR was far stronger than that between silica and IIR. However, the silica Vulksail N filled IIR had better wet-grip and lower rolling resistance compared to the carbon black-filled IIR should IIR be chosen as a substitute of styrene-butadiene rubber (SBR) in tire tread. The reinforcing factor, R, R (related to the difference in tan d peak height at Tg for the filled and nonfilled rubbers), also demonstrated that the N234-IIR interaction was stronger than for the silica. IIR with 30 phr N234 exhibited the largest tensile strength, 20.1 MPa, for those vulcanizates examined. The tensile and tear strengths of N234 filled IIR were higher than those of IIR with similar amounts of silica. Thus, it was concluded that N234 is a more active reinforcing filler in IIR than silica (Vulksail N) even with a silane coupling agent (Si-69). 相似文献
900.