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481.
Prof. Dr. Yun Gong Tao Wu Jinghua Li Jianbo Qin Xiaoxia Wu Rong Cao 《无机化学与普通化学杂志》2012,638(2):473-481
Eight metal(II) complexes based on imidazo[4, 5‐f]‐1, 10‐phenanthroline (HIMP) and bridging dicarboxylato ligands such as 4, 4′‐biphenyldicarboxylic acid (H2BPDC), 1, 4‐benzenedicarboxylic acid (H2BDC), thiophene‐2, 5‐dicarboxylic acid (H2TDC), and 2, 6‐naphthalenedicarboxylic acid (H2NDC) were hydrothermally synthesized and structurally characterized by single‐crystal X‐ray diffraction. Complexes 1 , 3 , 6 , and 7 are molecular dinuclear metal complexes. Complexes 2 , 4 , and 5 exhibit chain‐like structures. Compound 8 shows a novel 3D architecture, in which ZnII dimers are connected by four NDC2– anions. In the metal(II) complexes, HIMP exhibits a similar chelating coordination mode. Different π ··· π stacking interactions are observed in the complexes. The emission of HIMP is completely quenched in complexes 1 – 4 due to the strong π ··· π stacking interactions in the structures. Complexes 5 – 8 exhibit different photoluminescence properties. Firstly, we quantitatively investigated the effect of the strong HIMP–HIMP stacking interactions on the emission quenching of HIMP in the metal complexes. It was found that a higher extent of π ··· π stacking interactions in the complexes resulted in a higher extent of the emission quenching of HIMP. The introduction of aromatic conjugated carboxylate groups into metal(II)‐HIMP complexes changed the extent of the strong π ··· π stacking interactions in the structures and thus the photoluminescence properties of the complexes. 相似文献
482.
Deng R Huang M Wang J Huang Y Yang J Feng J Wang X 《Computational Biology and Chemistry》2006,30(4):300-302
Phylogenetic Tree Reconstruction (PTreeRec) is a web-based tool for automatic phylogeny inferences from whole-genome sequences, which accepts files of DNA sequences in the FASTA format and allows users to save the output tree file, and displays the inferred tree through an applet in a web browser. PTreeRec involves three basic steps. First, regions of maximal segment pairs (MSPs) based on an all-against-all pairwise comparison of genomes are located. Second, a distance matrix is calculated from MSP scores or coverage. Finally, a phylogenetic tree is reconstructed by the neighbor-joining method. 相似文献
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In this paper, we have established some compact imbedding theorems for some subspaces of W1,p(x)(U) when the underlying domain U is unbounded. The domain we consider is mainly of type RN(N≥2) or RL×Ω(L≥2), where Ω⊂RM is a bounded domain with smooth boundary. 相似文献
485.
Jinghua Yu Ping Dai Fuwei Wan Bo Li Shenguang Ge 《Journal of separation science》2009,32(12):2170-2179
Fenfluramine-imprinted polymer was prepared by self assembly with acrylic amide as functional monomer and ethylene glycol dimethacrylate as crosslinker. The binding characteristics of the imprinted polymer to fenfluramine were evaluated by equilibrium binding experiments and the morphology was studied by SEM. Taking the imprinted polymer as recognition material, using the new 3-p-nitrylphenyl-5-(4′-methyl-2′-sulfonophenylazo)rhodanine (M4NRASP) synthesized by the authors as chemiluminescence reagent, a new highly selective flow injection chemiluminescence sensor for trace fenfluramine with good sensitivity was established which utilized the chemiluminescence reaction between fenfluramine, M4NRASP, and potassium permanganate in hydrochloric acid. The traditional flow-through cell was replaced with a polymethyl methacrylate module, with Y-shaped flow path, through which the above three reactants were injected simultaneously. Under optimum conditions the relative chemiluminescence intensity shows a linear relationship with the concentration of fenfluramine over the range of 5×10–7 to 8×10–6 g/mL with a lower detection limit of 3.4×10–8 g/mL. The relative standard deviation for the determination of 1.0×10–6 g/mL fenfluramine solution was 2.4% (n = 11). This proposed sensor could be satisfactorily applied to the determination of fenfluramine in weight-reducing capsules. 相似文献
486.
在洁净K9玻璃基底上沉积TiO2薄膜,将透射光谱和X射线反射光谱相结合分析获得膜层的厚度和光学常数。X射线反射谱拟合能精确得到膜层的厚度、电子密度及表面和界面粗糙度,其中膜层厚度的数值为透射光谱的分析提供了重要参考。基于Forouhi-Bloomer色散模型拟合膜层透射光谱,得到薄膜折射率和消光系数,理论曲线和实验曲线吻合良好。对于同一样品,两种光谱拟合分析得到的厚度数值非常接近,差值最大为4.9nm,说明两种方法的结合能够提高光学分析结果的可靠性。 相似文献
487.
Meng Zhang Fuwei Wan Shaowei Wang Shenguang Ge Mei Yan Jinghua Yu 《Journal of luminescence》2012,132(4):938-943
A novel flow injection method for detection of l-proline was proposed in the presence of CdTe quantum dots (QDs). This method is based on the enhanced anodic electrochemiluminescence (ECL) emission of CdTe QDs l-proline in aqueous system. CdTe QDs were modified with thioglycolic acid to obtain stable water-soluble QDs and intensive anodic ECL emission in Na2CO3–NaHCO3 buffer solution at an indium tin oxide (ITO) electrode, which was used for the sensitive detection of ECL enhancement using our homemade flow cell. Under the optimal conditions, the ECL intensity was correlated linearly with the concentration of l-proline over the range of 1.0×10?8?1.0×10?4 g mL?1 (r=0.9996) and the detection limit was 5.0×10?9 g mL?1. The relative standard deviation was 1.12% for 6.0×10?5 g mL?1 l-proline (n=11). The possible mechanism was discussed. This method put forward a new efficient ECL methodology for enhancement-related determination of l-proline successfully. 相似文献
488.
“铁丝在氧气中燃烧”是初中化学教材中证明氧气化学性质的一个演示实验,该实验证明了氧气比较活泼,在一定条件下可以和金属发生剧烈反应。但是与木炭在氧气中燃烧、硫在氧气中燃烧、蜡烛在氧气中燃烧的演示实验相比,铁丝在氧气中燃烧的实验存在着一些不足的地方,针对这些不足,对铁丝在氧气中燃烧的实验进行了改进。1实验存在的问题按照教材要求,铁丝在氧气中燃烧的实验,须将铁丝绕成螺旋状,并在铁丝的末端绑上一根火柴杆,实验时先将火柴杆点燃,待火柴杆将燃尽时,迅速伸入盛满氧气的集气瓶中。这样的操作存在2个问题:第一,火柴燃烧的程度不… 相似文献
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