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31.
Xi‐Sha Zhang Yun‐Fei Zhang Zhao‐Wei Li Fei‐Xian Luo Zhang‐Jie Shi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(18):5568-5572
A rhodium(III)‐catalyzed cross‐coupling of benzyl thioethers and aryl carboxylic acids through the two directing groups is reported. Useful structures with diverse substituents were efficiently synthesized in one step with the cleavage of four bonds (C H, C S, O H) and the formation of two bonds (C C, C O). The formed structure is the privileged core in natural products and bioactive molecules. This work highlights the power of using two different directing groups to enhance the selectivity of a double C H activation, the first of such examples in cross‐oxidative coupling. 相似文献
32.
In quantum mechanics, the expectation value of an operator can be measured by using the projective measurement, ifthe coupling between the measured system and pointer is strong enough. However in the weak coupling regime, the pointercan not show all the eigenvalue of the physical quantity directly due to the overlapping among the pointer states, whichmakes the measurement of the expectation value difficult. In this paper, we propose an expectation value measurementmethod in the weak coupling regime inspired by the weak measurement scheme. Compared to the projective measurement,our scheme has two obvious advantages. Experimentally we use the internal state and motional state of a single trapped40Ca+ to establish the measurement scheme and realize the proof of principle demonstration of the scheme. 相似文献
33.
A new asymmetric Salamo‐based ligand H2L was synthesized using 3‐tert‐butyl‐salicylaldehyde and 6‐methoxy‐2‐[O‐(1‐ethyloxyamide)]‐oxime‐1‐phenol. By adjusting the ratio of the ligand H2L and Cu (II), Co (II), and Ni (II) ions, mononuclear, dinuclear, and trinuclear transition metal (II) complexes, [Cu(L)], [{Co(L)}2], and [{Ni(L)(CH3COO)(CH3CH2OH)}2Ni] with the ligand H2L possessing completely different coordination modes were obtained, respectively. The optical spectra of ligand H2L and its Cu (II), Co (II) and Ni (II) complexes were investigated. The Cu (II) complex is a mononuclear structure, and the Cu (II) atom is tetracoordinated to form a planar quadrilateral structure. The Co (II) complex is dinuclear, and the two Co (II) atoms are pentacoordinated and have coordination geometries of distorted triangular bipyramid. The Ni (II) complex is a trinuclear structure, and the terminal and central Ni (II) atoms are all hexacoordinated, forming distorted octahedral geometries. Furthermore, optical properties including UV–Vis, IR, and fluorescence of the Cu (II), Co (II), and Ni (II) complexes were investigated. Finally, the antibacterial activities of the Cu (II), Co (II), and Ni (II) complexes were explored. According to the experimental results, the inhibitory effect was found to be enhanced with increasing concentrations of the Cu (II), Co (II), and Ni (II) complexes. 相似文献
34.
Kai Cheng Xiao-Shuai Zhang Jie An Cheng Li Ruo-Yun Zhang Run Ye Prof. Dr. Bang-Jiao Ye Prof. Dr. Bo Liu Prof. Dr. Yuan-Di Zhao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(31):7553-7560
Given their superior penetration depths, photosensitizers with longer absorption wavelengths present broader application prospects in photodynamic therapy (PDT). Herein, Ag2S quantum dots were discovered, for the first time, to be capable of killing tumor cells through the photodynamic route by near-infrared light irradiation, which means relatively less excitation of the probe compared with traditional photosensitizers absorbing short wavelengths. On modification with polydopamine (PDA), PDA-Ag2S was obtained, which showed outstanding capacity for inducing reactive oxygen species (increased by 1.69 times). With the addition of PDA, Ag2S had more opportunities to react with surrounding O2, which was demonstrated by typical triplet electron spin resonance (ESR) analysis. Furthermore, the PDT effects of Ag2S and PDA-Ag2S achieved at longer wavelengths were almost identical to the effects produced at 660 nm, which was proved by studies in vitro. PDA-Ag2S showed distinctly better therapeutic effects than Ag2S in experiments in vivo, which further validated the enhanced regulatory effect of PDA. Altogether, a new photosensitizer with longer absorption wavelength was developed by using the hitherto-unexplored photodynamic function of Ag2S quantum dots, which extended and enhanced the regulatory effect originating from PDA. 相似文献
35.
36.
Shuqi Wang Tianyu Cai Huixiang Liu Aijuan Yang Jie Xing 《Journal of separation science》2019,42(21):3330-3339
The traditional antimalarial herb Artemisia annua L., from which artemisinin is isolated, is widely used in endemic regions. It has been suggested that artemisinin activity can be enhanced by flavonoids in A. annua; however, how fast and how long the flavonoids are present in the body remains unknown. In the present study, a rapid and sensitive liquid chromatography with tandem mass spectrometry method was developed and validated for the simultaneous determination of three major flavonoids components, i.e. chrysosplenol D, chrysoplenetin, and artemetin and their glucuronidated metabolites in rats after oral administrations of A. annua extracts at a therapeutic ultra‐low dose. The concentration of the intact form was determined directly, and the concentration of the glucuronidated form was assayed in the form of flavonoids aglycones, after treatment with β‐glucuronidase/sulfatase. The method was linear in the range of 0.5–300.0 ng/mL for chrysoplenetin and artemetin, and 2–600 ng/mL for chrysosplenol D. All the validation data conformed to the acceptance requirements. The study revealed a significantly higher exposure of the flavonoid constituents in conjugated forms in rats, with only trace intact from. Multiple oral doses of A. annua extracts led to a decreased plasma concentration levels for three flavonoids. 相似文献
37.
煤直接液化油中混合酚的分离研究 《燃料化学学报》2019,47(11):1298-1304
利用分子筛择形特点,对煤直接液化油中的混合酚实施高效分离。本研究选取间甲酚和对甲酚作为分离煤直接液化油馏分段混合酚的模型化合物,采用化学液相沉积法对HZSM-5吸附剂的孔口结构进行改变,分析分子筛硅铝比及颗粒粒径对模型化合物间甲酚和对甲酚吸附分离性能的影响,以获得高性能固相吸附剂,并将其应用于180-190℃馏分段混合酚分离。结果表明,当分子筛硅铝比为25、粒径为3-5 μm时,分子筛的孔口结构调节效果最优;当正硅酸乙酯的最小用量为0.2 mL/g时,固相吸附剂的吸附量为0.03 g/g,对甲酚选择性高于95%。由于外表面沉积物对吸附剂的孔口结构变化,导致对甲酚选择性的提高。进一步采用HZSM-5(1)吸附剂对真实煤直接液化油混合酚的分离中发现,苯酚和对甲酚的选择性均达到100%。 相似文献
38.
针对水下椭球粒子,以声散射理论为基础,采用分波序列的方法,建立了椭球粒子声辐射力的理论计算模型。进而根据声辐射力计算公式,以刚性椭球粒子和液体椭球粒子为例,计算并分析不同Bessel波束作用下椭球粒子的轴向声辐射力函数特征。数值仿真计算结果表明,对于刚性椭球粒子,扁平椭球粒子相对于细长椭球粒子更有助于激发负声辐射力;对于液体椭球粒子,细长椭球粒子相对于扁平椭球粒子更加容易产生负声辐射力;对于不同介质的椭球粒子,不同的入射波束激发的负声辐射力的效果也存在明显的差异。该结果为复杂的尺寸和介质粒子声操控技术提供了理论的可行性。 相似文献
39.
Dr. Zhe Zhang Dr. Xiaofeng Fang Dr. Zhihe Liu Dr. Haichao Liu Dr. Dandan Chen Prof. Shuqing He Prof. Jie Zheng Prof. Bing Yang Prof. Weiping Qin Prof. Xuanjun Zhang Prof. Changfeng Wu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(9):3720-3727
Fluorescence probes in the NIR-IIa region show drastically improved imaging owing to the reduced photon scattering and autofluorescence in biological tissues. Now, NIR-IIa polymer dots (Pdots) are developed with a dual fluorescence enhancement mechanism. First, the aggregation induced emission of phenothiazine was used to reduce the nonradiative decay pathways of the polymers in condensed states. Second, fluorescence quenching was minimized by different levels of steric hindrance to further boost the fluorescence. The resulting Pdots displayed a fluorescence QY of ca. 1.7 % in aqueous solution, suggesting an enhancement of ca. 21 times in comparison with the original polymer in tetrahydrofuran (THF) solution. Small-animal imaging by using the NIR-IIa Pdots exhibited a remarkable improvement in penetration depth and signal to background ratio, as confirmed by through-skull and through-scalp fluorescent imaging of the cerebral vasculature of live mice. 相似文献
40.
Jie Lu Ju-Kang Wu Yao Jiang Dr. Peng Tan Lin Zhang Yu Lei Prof. Xiao-Qin Liu Prof. Lin-Bing Sun 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(16):6490-6496
Hierarchically porous metal–organic frameworks (HP-MOFs) are promising in various applications. Most reported HP-MOFs are prepared based on the generation of mesopores in microporous frameworks, and the formed mesopores are connected by microporous channels, limiting the accessibility of mesopores for bulky molecules. A hierarchical structure is formed by constructing microporous MOFs in uninterrupted mesoporous tunnels. Using the confined space in as-prepared mesoporous silica, highly dispersed metal precursors for MOFs are coated on the internal surface of mesoporous tunnels. Ligand vapor-induced crystallization is employed to enable quantitative formation of MOFs in situ, in which sublimated ligands diffuse into mesoporous tunnels and react with metal precursors. The obtained hierarchically porous composites exhibit record-high adsorption capacity for the bulky molecule trypsin. The thermal and storage stability of trypsin is improved upon immobilization on the composites. 相似文献