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951.
Controllable Release and High‐Efficiency Collection of Hydrogen Peroxide: Application on the Quantitative Investigation of Biomolecule Oxidation Induced by Reactive Oxygen Species 下载免费PDF全文
Hydrogen peroxide and hydroxyl radical, both important members of the reactive oxygen species (ROS) family, can cause serious oxidative damages in biological systems. In order to proclaim and prevent oxidation stress, researches on the biomolecule oxidation induced by H2O2 or OH. are in crucial need. However, due to the high reactivity of ROS, traditional methods are difficult to achieve the in situ quantitative investigations on those reactions involving ROS. In this work, using scanning electrochemical microscopy technique (SECM) in a tip generation‐substrate collection mode (TG‐SC), the controllable release and the high‐efficiency collection of electrogenerated H2O2 were achieved. Compared to ex situ fluorescence method, SECM improved the collection efficiency approximately two times larger. Based on it, SECM combined with surface plasmon resonance (SPR) was employed to in situ monitor the protein oxidation (taking Cu12+? MT as a model) induced by H2O2. OH., which was generated from the interaction between H2O2 and Cu12+? MT, can attack the peptide chain and induced the unrepairable protein oxidation damage. The whole process was quantitatively characterized by SPR, and the linear relationship between SPR dip shift and the amounts of released H2O2 was successfully built. Our work proves that the combined SECM‐SPR technique can realize the in situ quantitative determinations of the biomolecule oxidation induced by ROS, which affords an avenue for further elucidation on the mechanisms of oxidation stress in organisms. 相似文献
952.
Approach to the study of flavone di‐C‐glycosides by high performance liquid chromatography‐tandem ion trap mass spectrometry and its application to characterization of flavonoid composition in Viola yedoensis 下载免费PDF全文
Jie Cao Chengle Yin Yan Qin Zhihong Cheng Daofeng Chen 《Journal of mass spectrometry : JMS》2014,49(10):1010-1024
The mass spectrometric (MS) analysis of flavone di‐C‐glycosides has been a difficult task due to pure standards being unavailable commercially and to that the reported relative intensities of some diagnostic ions varied with MS instruments. In this study, five flavone di‐C‐glycoside standards from Viola yedoensis have been systematically studied by high performance liquid chromatography‐electrospray ionization‐tandem ion trap mass spectrometry (HPLC‐ESI‐IT‐MSn) in the negative ion mode to analyze their fragmentation patterns. A new MS2 and MS3 hierarchical fragmentation for the identification of the sugar nature (hexoses or pentoses) at C‐6 and C‐8 is presented based on previously established rules of fragmentation. Here, for the first time, we report that the MS2 and MS3 structure‐diagnostic fragments about the glycosylation types and positions are highly dependent on the configuration of the sugars at C‐6 and C‐8. The base peak (0,2X10,2X2? ion) in MS3 spectra of di‐C‐glycosides could be used as a diagnostic ion for flavone aglycones. These newly proposed fragmentation behaviors have been successfully applied to the characterization of flavone di‐C‐glycosides found in V. yedoensis. A total of 35 flavonoid glycosides, including 1 flavone mono‐C‐hexoside, 2 flavone 6,8‐di‐C‐hexosides, 11 flavone 6,8‐di‐C‐pentosides, 13 flavone 6,8‐C‐hexosyl‐C‐pentosides, 5 acetylated flavone C‐glycosides and 3 flavonol O‐glycosides, were identified or tentatively identified on the base of their UV profiles, MS and MSn (n = 5) data, or by comparing with reference substances. Among these, the acetylated flavone C‐glycosides were reported from V. yedoensis for the first time. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
953.
Min Cheng Daoyuan Kang Xiaoli Zhang Huawei Yin Yuhong Wang 《Crystal Research and Technology》2015,50(4):331-337
Comparing with the traditional concentric rotation method (rotation radius is 0 cm), the effects of different rotation radii on the growth rate of KDP crystals were studied by experimental methods. It was found that with the increase of rotation radius from 0 cm, the growth rate of each direction of crystals first increased and then decreased in a size‐unchanged vessel. The smaller the distance between the crystal and vessel wall, the less the growth rate. This phenomenon was named the “wall collision effect”. Also, the value of growth rate reached a maximum when the rotation radius was about half of its allowable largest value in the size‐unchanged vessel. In addition, an increase of the rotation radius could improve the crystal growth rate under the same linear velocity of crystal movement. Finally, the uniformity of crystal growth has also been analyzed compared with the concentric rotation radius. It was found that the uniformity of crystal growth was best when the rotation radius was half of its allowable maximum value, and it was more conducive to the actual application of KDP crystals. 相似文献
954.
Polymers based on styrene (STY) and divinylbenzene (DVB) are widely used for water treatment. The chemical modification of these materials, with the introduction of chemical groups, increases their selectivity for certain types of contaminants. The incorporation of magnetic particles makes these systems useful for removing contaminants from aquifers, due to their magnetic attraction of certain residues. In this work, STY–DVB resins (unmodified, sulfonated, and impregnated with nickel and cobalt particles) were analyzed by thermogravimetry. The thermal stabilities of all the samples were compared, showing that sulfonation reduces the thermal stability of the resin, but the incorporation of metal particles restores that stability, with the extent of this recovery depending on the type of metal. This result shows that even when the incorporation of metal particles does not involve removal of contaminants by magnetic attraction, this inclusion is still justified because it increases the material’s thermal stability and also makes it more efficient for removing certain types of non-metallic contaminants, as observed in a previous study. Besides this, the thermogravimetric analysis was highly useful to ascertain the changes caused to the materials, including allowing inferences on the semi-quantitative results of the degree of sulfonation and confirming that metal compounds are not only physical mixtures. 相似文献
955.
Wei-Ting Chen Wei-Chun Chen Kuang-Hua Hsueh Chen-Wei Chiu Chi-Min Shu 《Journal of Thermal Analysis and Calorimetry》2014,118(2):1085-1094
The rapid development of the petrochemical industry of Taiwan over the past four decades has resulted in a booming economy in Taiwan that drives derived industries to develop progressively. However, it has also caused many runaway reaction accidents, such as toxic gas release, fire, and explosion. It is crucial to eliminate those potential hazard factors which can induce consequent runaway reaction accidents during the life span of the manufacturing process. In response to this crucial issue, we performed a thermokinetic parameter analysis for 1,1-bis-(tert-butylperoxy)-3,3,5-trimethylcyclohexane at isothermal conditions to conduct a thermal safety assessment of chemical materials. The five isothermal temperatures, 90, 100, 110, 120, 130, and 140 °C, measured by DSC, were adopted in this study to calculate process safety parameters, including TMRad, T NR, and SADT, which can be employed in process safety parameters for the manufacturing process. A novel, green kinetic approach accompanied with non-isothermal DSC results is used to derive thermokinetic parameters in safety protocol in this study. 相似文献
956.
Guishan Zou Xiukang Yang Xianyou Wang Long Ge Hongbo Shu Yansong Bai Chun Wu Haipeng Guo Liang Hu Xin Yi Bowei Ju Hai Hu Di Wang Ruizhi Yu 《Journal of Solid State Electrochemistry》2014,18(7):1789-1797
The Li-rich Li1.3[Ni0.35Mn0.65]O2+x microspheres are firstly prepared and subsequently transferred into the Al2O3-coated Li-rich Li1.3[Ni0.35Mn0.65]O2+x microspheres by a simple deposition method. The as-prepared samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge/discharge tests. The results reveal that the Al2O3-coated Li-rich Li1.3[Ni0.35Mn0.65]O2+x sample has a typical α-NaFeO2 layered structure with the existence of Li2MnO3-type integrated component, and the Al2O3 layer is uniformly coated on the surface of the spherical Li-rich Li1.3[Ni0.35Mn0.65]O2+x particles with a thickness of about 4 nm. Importantly, the Al2O3-coated Li-rich sample exhibits obviously improved electrochemical performance compared with the pristine one, especially the 2 wt.% Al2O3-coated sample shows the best electrochemical properties, which delivers an initial discharge capacity of 228 mAh g?1 at a rate of 0.1 C in the voltage of 2.0–4.6 V, and the first coulombic efficiency is up to 90 %. Furthermore, the 2 wt.% Al2O3-coated sample represents excellent cycling stability with capacity retention of 90.9 % at 0.33 C after 100 cycles, much higher than that of the pristine one (62.2 %). Particularly, herein, the typical inferior rate capability of Li-rich layered cathode is apparently improved, and the 2 wt.% Al2O3-coated sample also shows a high rate capability, which can deliver a capacity of 101 mAh g?1 even at 10 C. Besides, the thin Al2O3 layer can reduce the charge transfer resistance and stabilize the surface structure of active material during cycling, which is responsible for the improvement of electrochemical performance of the Li-rich Li1.3[Ni0.35Mn0.65]O2+x . 相似文献
957.
Multi‐Colored Fibers by Self‐Assembly of DNA,Histone Proteins,and Cationic Conjugated Polymers 下载免费PDF全文
Fengyan Wang Zhang Liu Bing Wang Dr. Liheng Feng Prof. Libing Liu Prof. Fengting Lv Prof. Yilin Wang Prof. Shu Wang 《Angewandte Chemie (International ed. in English)》2014,53(2):424-428
The development of biomolecular fiber materials with imaging ability has become more and more useful for biological applications. In this work, cationic conjugated polymers (CCPs) were used to construct inherent fluorescent microfibers with natural biological macromolecules (DNA and histone proteins) through the interfacial polyelectrolyte complexation (IPC) procedure. Isothermal titration microcalorimetry results show that the driving forces for fiber formation are electrostatic and hydrophobic interactions, as well as the release of counterions and bound water molecules. Color‐encoded IPC fibers were also obtained based on the co‐assembly of DNA, histone proteins, and blue‐, green‐, or red‐ (RGB‐) emissive CCPs by tuning the fluorescence resonance energy‐transfer among the CCPs at a single excitation wavelength. The fibers could encapsulate GFP‐coded Escherichia coli BL21, and the expression of GFP proteins was successfully regulated by the external environment of the fibers. These multi‐colored fibers show a great potential in biomedical applications, such as biosensor, delivery, and release of biological molecules and tissue engineering. 相似文献
958.
Dr. Hongli Bao Liela Bayeh Prof. Uttam K. Tambar 《Angewandte Chemie (International ed. in English)》2014,53(6):1664-1668
New advances in the functionalization of unactivated olefins with carbon nucleophiles have provided more efficient and practical approaches to convert inexpensive starting materials into valuable products. Recent examples have been reported with stabilized carbon nucleophiles, tethered carbon nucleophiles, diazoesters, and trifluoromethane donors. A general method for functionalizing olefins with aromatic, aliphatic, and vinyl Grignard reagents was developed. In a one‐pot process, olefins are oxidized by a commercially available reagent to allylic electrophiles, which undergo selective copper‐catalyzed allylic alkylation with Grignard reagents. Products are formed in high yield and with high regioselectivity. This was utilized to synthesize a series of skipped dienes, a class of compounds that are prevalent in natural products and are difficult to synthesize by known allylic alkylation methods. 相似文献
959.
Asymmetric NH Insertion of Secondary and Primary Anilines under the Catalysis of Palladium and Chiral Guanidine Derivatives 下载免费PDF全文
Yin Zhu Prof. Dr. Xiaohua Liu Dr. Shunxi Dong Yuhang Zhou Wei Li Dr. Lili Lin Prof. Dr. Xiaoming Feng 《Angewandte Chemie (International ed. in English)》2014,53(6):1636-1640
Efficient enantioselective N? H insertion reactions of secondary and primary anilines were catalyzed by palladium(0) in combination with chiral guanidine derivatives. A broad range of substituted anilines were tolerated, and the corresponding products were obtained in high yield (up to 99 %) with good enantioselectivity (up to 94 % ee) under mild reaction conditions. The N? H insertion mechanism was examined by the study of kinetic isotope effects, control experiments, HRMS, and spectroscopic analysis. 相似文献
960.
Pumping through Porous Hydrophobic/Oleophilic Materials: An Alternative Technology for Oil Spill Remediation 下载免费PDF全文
Jin Ge Yin‐Dong Ye Hong‐Bin Yao Xi Zhu Xu Wang Liang Wu Jin‐Long Wang Prof. Hang Ding Prof. Ni Yong Prof. Ling‐Hui He Prof. Dr. Shu‐Hong Yu 《Angewandte Chemie (International ed. in English)》2014,53(14):3612-3616
Recently, porous hydrophobic/oleophilic materials (PHOMs) have been shown to be the most promising candidates for cleaning up oil spills; however, due to their limited absorption capacity, a large quantity of PHOMs would be consumed in oil spill remediation, causing serious economic problems. In addition, the complicated and time‐consuming process of oil recovery from these sorbents is also an obstacle to their practical application. To solve the above problems, we apply external pumping on PHOMs to realize the continuous collection of oil spills in situ from the water surface with high speed and efficiency. Based on this novel design, oil/water separation and oil collection can be simultaneously achieved in the remediation of oil spills, and the oil sorption capacity is no longer limited to the volume and weight of the sorption material. This novel external pumping technique may bring PHOMs a step closer to practical application in oil spill remediation. 相似文献