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251.
针对露天矿炮区工作面中穿爆作业不规律导致爆破效果不佳现象,通过在胜利露天矿进行爆破试验得到实测数据,利用分形理论中分维数与爆破破碎块度的关系,计算出异位孔连续装药结构岩石爆破破碎块度的分维区间,与其设计孔爆破破碎块度分维区间进行对比分析,对异位孔爆破破碎块度分维区间进行优化,利用工程实测方法与分形理论相结合找到最佳的爆破参数,以达到不规则作业面最佳爆破效果. 相似文献
252.
Lanlan Jiang Xinhuan Zhou Yongchen Song Yu Liu Mingjun Yang Minghao Yu 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2014,88(12):2214-2219
The objective of this study was to understand fluid heat and mass transfer processes in porous media with different pore structures. High-resolution Magnetic Resonance Imaging was used to measure fluid flow velocity and temperature maps in porous media. Firstly, three orthogonal velocity components (V x , V y , and V z ) of single phase flow measurement were evaluated. The flow distribution in porous media is rather heterogeneous, and it is consistent with heterogeneous pore structure, and the velocity in large pore is high. Then we presented initial results from the extension of this work to two-phase flow. The CO2 channeling phenomena were obvious. And the CO2 velocity was calculated from saturation of water. Finally, the linearity relationship between temperature and the MRI parameter was determined for porous media, and we measured the temperature distribution of water saturated porous media. The study provides useful data for heat and mass process during CO2 storage. 相似文献
253.
Towards Molecular Construction Platforms: Synthesis of a Metallotricyclic Spirane Based on Bis(2,2′:6′,2“‐Terpyridine)RuII Connectivity 下载免费PDF全文
Dr. Ting‐Zheng Xie Kai Guo Mingjun Huang Dr. Xiaocun Lu Sheng‐Yun Liao Rajarshi Sarkar Dr. Charles N. Moorefield Prof. Stephen Z. D. Cheng Prof. Chrys Wesdemiotis Prof. George R. Newkome 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(36):11291-11294
The design and construction of the first multicomponent stepwise assembly of a <tpy‐RuII‐tpy>‐based (tpy=terpyridine), three‐dimensional, propeller‐shaped trismacrocycle, 8 , are reported. Key steps in the synthesis involve the preparation of a hexaterpyridinyl triptycene and its reaction with dimeric, 60°‐directional, bisterpyridine‐RuII building blocks. Characterization includes ESI‐ and ESI‐TWIM‐MS and TEM, along with 1D and 2D 1H NMR spectroscopy. 相似文献
254.
Dr. Xianghe Meng Xingyu Zhang Qingxiong Liu Dr. Zhengyang Zhou Dr. Xingxing Jiang Prof. Yonggang Wang Prof. Zheshuai Lin Prof. Mingjun Xia 《Angewandte Chemie (International ed. in English)》2023,62(1):e202214848
Nonlinear optical (NLO) crystal, which simultaneously exhibits strong second-harmonic-generation (SHG) response and desired optical anisotropy, is a core optical material accessible to the modern optoelectronics. Accompanied by strong SHG effect in a NLO crystal, a contradictory problem of overlarge birefringence is ignored, leading to low frequency doubling efficiency and poor beam quality. Herein, a series of rare earth cyanurates RE5(C3N3O3)(OH)12 (RE=Y, Yb, Lu) were successfully characterized by 3D electron diffraction technique. Based on a “three birds with one stone” strategy, they enable the simultaneous fulfillment of strong SHG responses (2.5–4.2× KH2PO4), short UV cutoff (ca. 220 nm) and applicable birefringence (ca. 0.15 at 800 nm) by the introduction of rare earth coordination control of π-conjugated (C3N3O3)3− anions. These findings provide high-performance short-wavelength NLO materials and highlight the exploration of cyanurates as a new research area. 相似文献
255.
Bidentate inhibitors of protein tyrosine phosphatase 1B (PTP1B) are considered as a group of ideal inhibitors with high binding potential and high selectivity in treating type II diabetes. In this paper, the binding models of five bidentate inhibitors to PTP1B, TCPTP, and SHP-2 were investigated and compared by using molecular dynamics (MD) simulations and free energy calculations. The binding free energies were computed using the Molecular Mechanics/Poisson-Boltzmann Surface Area (MM/PBSA) methodology. The calculation results show that the predicted free energies of the complexes are well consistent with the experimental data. The Molecular Mechanics/Generalized Born Surface Area (MM/GBSA) free energy decomposition analysis indicates that the residues ARG24, ARG254, and GLN262 in the second binding site of PTP1B are essential for the high selectivity of inhibitors. Furthermore, the residue PHE182 close to the active site is also important for the selectivity and the binding affinity of the inhibitors. According to our analysis, it can be concluded that in most cases the polarity of the portion of the inhibitor that binds to the second binding site of the protein is positive to the affinity of the inhibitors while negative to the selectivity of the inhibitors. We expect that the information we obtained here can help to develop potential PTP1B inhibitors with more promising specificity. 相似文献
256.
以纳米管钛酸为前驱体,采用水热法制备了Pt掺杂TiO2样品.水热反应过程中,纳米管钛酸表面羟基与氯铂酸发生酸碱中和反应,导致反应后pH值升高;在130°C开始纳米管钛酸晶体结构由正交晶系转变为锐钛矿相TiO2.表面化学组成分析表明,掺杂的Pt主要以+2价形式存在.以丙烯为模型污染物,评价样品的可见光(λ≥420nm)光催化活性.结果表明,Pt-TiO2具有明显的可见光光催化降解丙烯的活性,其中160°C水热处理制得的Pt-TiO2活性最高.最后讨论了低温水热法Pt掺杂的形成机理及Pt-TiO2具有可见光响应的原因. 相似文献
257.
In this study,a numerical model is developed to investigate the hydrate dissociation and gas production in porous media by depressurization.A series of simulation runs are conducted to study the impacts of permeability characteristics,including permeability reduction exponent,absolute permeability,hydrate accumulation habits and hydrate saturation,sand average grain size and irreducible water saturation.The effects of the distribution of hydrate in porous media are examined by adapting conceptual models of hydrate accumulation habits into simulations to govern the evolution of permeability with hydrate decomposition,which is also compared with the conventional reservoir permeability model,i.e.Corey model.The simulations show that the hydrate dissociation rate increases with the decrease of permeability reduction exponent,hydrate saturation and the sand average grain size.Compared with the conceptual models of hydrate accumulation habits,our simulations indicate that Corey model overpredicts the gas production and the performance of hydrate coating models is superior to that of hydrate filling models in gas production,which behavior does follow by the order of capillary coating>pore coating>pore filling>capillary filling.From the analysis of t1/2,some interesting results are suggested as follows:(1) there is a "switch" value(the"switch"absolute permeability) for laboratory-scale hydrate dissociation in porous media,the absolute permeability has almost no influence on the gas production behavior when the permeability exceeds the "switch" value.In this study,the "switch" value of absolute permeability can be estimated to be between 10 and 50 md.(2) An optimum value of initial effective water saturation Sw,e exists where hydrate dissociation rate reaches the maximum and the optimum value largely coincides with the value of irreducible water saturation S wr,e.For the case of Sw,Swr,e,there are different control mechanisms dominating the process of hydrate dissociation and gas production. 相似文献
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260.
用超临界CO_2制备微孔聚苯乙烯/热致液晶聚合物原位复合材料 总被引:4,自引:0,他引:4
微孔聚合物是80年代初发明的一种新型多孔材料,其特征为:泡孔直径1~10 μm,泡孔密度109~1012cells/cm3,相对密度0.05~0.95.具有缺口冲击强度高、韧性高、比强度高、疲劳寿命长、热稳定性高、介电常数低和导热系数低等优异性能.同时,制备微孔聚合物使用无公害、易回收的CO2和N2替代对臭氧层有害的氯氟烃(氟利昂)和易燃的碳氢化合物等作为发泡剂,是一种新型绿色材料[1].在微孔聚合物中使用超临界流体是90年代初提出的新方法[2~4],可缩短加工时间,同时制得泡孔直径更小、泡孔密度更大的微孔材料.目前研究中,对聚合物多相体系的研究报道很少,只有HIPS[5]、PE/iPP[6]和PVC/木纤维复合材料[7]等少数体系的报道,而聚合物多相体系的研究是材料科学的主要研究领域.可以预见,加入少量第二组分的共混物为基体的微孔材料可以达到更为优异的性能.本工作选择聚苯乙烯与热致液晶聚合物的原位复合材料为研究对象,采用超临界CO2快速降压法[3]制备微孔材料.在前期工作中,报道了该材料是一种综合了液晶聚合物的高强度和聚苯乙烯微孔材料轻质、高抗冲、保温隔音性能的具有仿生结构的新型复合材料[8].本文在此基础上,进一步研究热致液晶聚合物的加入对微孔结构的影响以及界面相容剂在微孔成型中的作用. 相似文献