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排序方式: 共有3932条查询结果,搜索用时 31 毫秒
1.
Sim Woojeong Lee Booyeong Kim Dong Ju Lee Jeong A Kim Jaewon Chung Jintai 《Nonlinear dynamics》2022,108(2):987-1004
Nonlinear Dynamics - This study analyzes the vibro-impact behavior of two adjacent cantilever beams subjected to vibration generated by applying harmonic excitation to their rigid base. For the... 相似文献
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为了校正大扫描视场机载共形窗口引入的像差,提出一种基于固定校正板和透镜阵列的静态校正方法。首先使用固定校正板校正静态像差;然后在像面前安置固定的透镜阵列,利用透镜阵列中的各个透镜单元分别校正不同扫描角度的动态像差;最后基于所提方法设计应用在机载共形光学系统中的像差校正器。设计结果表明,所提方法在±42°的扫描视场范围内能够良好地校正共形窗口引入的像差。与其他动态或静态校正方法相比,所提方法可以实现大扫描视场机载共形光学系统像差的校正,同时降低机载共形光学系统的质量,提高系统的稳定性。 相似文献
4.
通过制备磁性大孔有机共聚物材料(Fe3O4@SiO2@PLS)和磁性金属有机骨架材料(Fe3O4@ZIF-8),将两种材料同时作为磁性吸附剂,建立了混合吸附剂磁性固相萃取/高效液相色谱-串联质谱(MSPE/HPLC-MS/MS)测定水中4种磺胺类和8种喹诺酮类抗生素残留的分析方法.通过扫描电子显微镜(SEM)、傅里叶变换红外光谱(FT-IR)和X-射线衍射仪(XRD)对两种磁性材料进行表面形貌和结构表征,结果显示,亲水亲脂大孔有机共聚物(PLS)包覆于磁性纳米粒子Fe3O4表面,且Fe3O4成功附着于正六边形金属有机骨架材料(ZIF-8)晶体表面,可以满足磁性固相萃取的要求.通过优化吸附剂用量、萃取方式、吸附时间、样品pH值、洗脱剂种类及洗脱时间,在最优的实验条件下,12种目标物的线性范围为0.5~10μg/L,相关系数(r2)为0.9961~0.9998,检出限(S/N=3)为0.01~0.14μg/L,定量下限(S/N=10)为0.04~0.45μg/L.所建方法成功用于水中12种目标抗生素的检测,在3个加标水平下的回收率为75.0%~107%,相对标准偏差(RSD)为0.50%~5.5%.该方法适用于水中痕量磺胺类和喹诺酮类抗生素残留的分析. 相似文献
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Nonlinear Dynamics - In this paper, we address the issue of $$\mathcal {H}_{\infty }$$ synchronization for two identical chaotic systems with time-varying delays and uncertainties under... 相似文献
6.
Yue Zhu Yujin Ji Zhengyu Ju Kang Yu Paulo J. Ferreira Yuanyue Liu Guihua Yu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(48):17365-17369
Solvents play an essential role in many areas of chemistry and is the cornerstone of understanding reactivity in solution‐phase reactions. Solvent effects have been widely observed in intercalation reactions; however, understanding of the influence of solvents on the thermodynamics and kinetics remains largely elusive in intercalation chemistry. Now, the solvent‐dependent kinetics of ferrocene intercalation into a layered vanadyl phosphate (VOPO4?2 H2O) host is presented, with a special focus on primary alcohols. From methanol to 1‐hexnaol, the intercalation rate peaks in 1‐propanol (80 times faster than the slowest case in methanol). Similar kinetics of exfoliation are also found in these solvents without ferrocene. The correlation between intercalation and exfoliation is understood at atomic level by DFT calculations, which reveal the role of pre‐intercalated solvent molecules play in intralayer interactions, interlayer expansion, and layer sliding. 相似文献
7.
Hongjuan Chen Peng Fan Xingxin Tu Hui Min Xianyong Yu Xiaofang Li Ju‐Lan Zeng Shaowei Zhang Peng Cheng 《化学:亚洲杂志》2019,14(20):3611-3619
The hydrothermal reaction of Zn2+ ions with a mixture of two ligands, Hcptpy and H3btc (Hcptpy=4‐(4‐carboxyphenyl)‐2,2′:4′,4′′‐terpyridine; H3btc=1,3,5‐benzenetricarboxylic acid), led to the formation of a 3D metal–organic framework (MOF) with 1D channels, [Zn2(cptpy)(btc)(H2O)]n ( 1 ), which was structurally characterized by using single‐crystal X‐ray diffraction (SXRD). In MOF 1 , two independent Zn2+ ions were interconnected by btc3? ligands to form a 1D chain, whilst adjacent Zn2+ ions were alternately bridged by cptpy? ligands to generate a 2D sheet, which was further linked by 1D chains to form a 3D framework with a new (3,3,4,4)‐connected topology. Furthermore, compound 1 also exhibited excellent stability towards air and water and, more importantly, luminescence experiments indicated that it could serve as a probe for the sensitive detection of paraquat (PAQ) and Fe3+ ions in aqueous solution. 相似文献
8.
We demonstrate a reversible shape‐morphing with concurrent fluorescence switching in the nanomaterials which are complexed with cucurbit[7]uril (CB[7]) in water. The cyanostilbene derivative alone forms ribbon‐like two‐dimensional (2D) nanocrystals with bright yellow excimeric emission in water (λem=540 nm, ΦF=42 %). Upon CB[7] addition, however, the ribbon‐like 2D nanocrystals immediately transform to spherical nanoparticles with significant fluorescence quenching and blue‐shifting (λem=490 nm, ΦF=1 %) through the supramolecular complexation of the cyanostilbene and CB[7]. Based on this reversible fluorescence switching and shape morphing, we could demonstrate a novel strategy of turn‐on fluorescence sensing of spermine and also monitoring of lysine decarboxylase activity. 相似文献
9.
Yongtao Bai Lihua Song Yongheng Zhang Guoliang Dai Weidong Zhang Shanshan Song Hong Sun Wen Jing Meijuan Xu Wenzheng Ju 《Biomedical chromatography : BMC》2019,33(9)
A highly selective and efficient LC–MS/MS method was developed to determine the plasma concentration of magnolol, hesperidin, neohesperidin and geniposide following oral administration of Zhi‐Zi‐Hou‐Po decoction in normal and depressed rats. Plasma samples were pretreated by protein precipitation with methanol. Chromatographic separation was performed on an XTerra® MS C18 column using a gradient elution with a mobile phase composed of acetonitrile–0.1% aqueous formic acid. The proposed method was validated to be specific, accurate and precise for the analytes determination in plasma samples. The calibration curves displayed good linearity over definite concentration ranges for the analytes. The intra‐ and inter‐day precision of the proposed method at three different levels were all within <11.13% and the relative errors ranged from ?8.46 to 8.93%. The recovery of the four compounds ranged from 82.72 to 89.08% and no apparent matrix effect was observed during sample analysis. After full validation, the established method was successfully applied for comparing the pharmacokinetics of four components between normal and depressed rats. The results showed that the AUC and Cmax of four analytes in depressed rats were significantly different from those in normal rats and might provide helpful information to guide the clinical use of Zhi‐Zi‐Hou‐Po to treat depression. 相似文献
10.
Yue Zhang Yue Zhang Guobin Song Yuling He Xiaobo Zhang Ying Liu Huangxian Ju 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(50):18375-18379
Stimulus‐responsive drug release possesses considerable significance in cancer therapy. This work reports an upconversion‐luminescence‐fueled DNA–azobenzene nanopump for rapid and efficient drug release. The nanopump is constructed by assembling the azobenzene‐functionalized DNA strands on upconversion nanoparticles (UCNPs). Doxorubicin (DOX) is loaded in the nanopump by intercalation in the DNA helix. Under NIR light, the UCNPs emit both UV and visible photons to fuel the continuous photoisomerization of azo, which acts as an impeller pump to trigger cyclic DNA hybridization and dehybridization for controllable DOX release. In a relatively short period, this system demonstrates 86.7 % DOX release. By assembling HIV‐1 TAT peptide and hyaluronic acid on the system, targeting of the cancer‐cell nucleus is achieved for perinuclear aggregation of DOX and enhanced anticancer therapy. This highly effective drug delivery nanopump could contribute to chemotherapy development. 相似文献