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981.
Yu‐Fang Wang Wen‐Min Wang Hao‐Fei Sun Wan‐Ting Wang Mei‐Ying Wang Yu‐Ting Tang Zhi‐Lei Wu 《无机化学与普通化学杂志》2019,645(22):1291-1295
Reaction of the Schiff base ligand H2L and dysprosium acetate result in a new planar Dy6 cluster [Dy6(μ3‐OH)L6(Ac)6] · MeOH ( 1 ) [H2L = N'‐(2‐hydroxybenzylidene)‐2‐(hydroxyimino)propanohydrazide, HAc = acetic acid], which was successfully structurally and magnetically characterized. Single‐crystal X‐ray diffraction analysis revealed that 1 contained a hexanuclear dysprosium cluster [Dy6], which is composed of four Dy3 triangular units. Magnetic measurements suggest that 1 displays single‐molecule magnet (SMM) behavior which is enhanced by applying a 4000 Oe direct‐current field. The effective anisotropic barrier Ueff/kB = 14.9 K and the pre‐exponential factor τ0 = 1.31 × 10–6 s are also obtained. This work may provide more insights for the design and investigation of lanthanide‐based SMMs. 相似文献
982.
Luqi Zhu Feifei Luo Zhi Li Ge Dai Pingang He Qingjiang Wang Qiming Chen 《Electrophoresis》2019,40(9):1331-1336
The release of cytochrome C (Cyt C) plays an important role in apoptosis. In this study, selective and sensitive detection of Cyt C based on an aptamer strategy coupled with MCE was developed. Following the binding of a specific aptamer to Cyt C, the aptamer exhibited an irregular state, reducing the binding affinity of a fluorescent probe, and thus preventing the aptamer‐Cyt C complexes from detection within the MCE. The height of the detection peak of the residual aptamer linearly decreased, and therefore, the difference in peak height of residual aptamer compared to that of the initial aptamer was used to quantify the captured protein concentration. Experimental conditions such as incubation time, pH, temperature, and ionic strength were optimized. A measurement of Cyt C concentration by MCE was achieved within 135 s, with a limit of detection as low as 0.4 nM. The proposed method has high selectivity and good stability for the detection of Cyt C. The experimental results demonstrate that this method is quick, consumes only a small quantity of sample, is highly selectivity and exhibits high sensitivity. 相似文献
983.
984.
985.
Hai‐Tao Zhou Chang‐Feng Wang Yao Liu Xiao‐Wei Fan Kang Yang Wen‐Juan Wei Yun‐Zhi Tang Yu‐Hui Tan 《化学:亚洲杂志》2019,14(21):3946-3952
Molecular ferroelectrics have displayed a promising future since they are light‐weight, flexible, environmentally friendly and easily synthesized, compared to traditional inorganic ferroelectrics. However, how to precisely design a molecular ferroelectric from a non‐ferroelectric phase transition molecular system is still a great challenge. Here we designed and constructed a molecular ferroelectric by double regulation of the anion and cation in a simple crown ether clathrate, 4 , [K(18‐crown‐6)]+[PF6]?. By replacing K+ and PF6? with H3O+ and [FeCl4]? respectively, we obtained a new molecular ferroelectric [H3O(18‐crown‐6)]+[FeCl4]?, 1 . Compound 1 undergoes a para‐ferroelectric phase transition near 350 K with symmetry change from P21/n to the Pmc21 space group. X‐ray single‐crystal diffraction analysis suggests that the phase transition was mainly triggered by the displacement motion of H3O+ and [FeCl4]? ions and twist motion of 18‐crown‐6 molecule. Strikingly, compound 1 shows high a Curie temperature (350 K), ultra‐strong second harmonic generation signals (nearly 8 times of KDP), remarkable dielectric switching effect and large spontaneous polarization. We believe that this research will pave the way to design and build high‐quality molecular ferroelectrics as well as their application in smart materials. 相似文献
986.
Nana Wang Tao Chen Xue Yang Cheng Shen Hongmei Li Shuo Wang Jingyang Zhao Jilin Chen Zhi Chen Yulin Li 《Journal of separation science》2019,42(9):1717-1724
Separation of minor compounds especially with similar polarities and structures from complex samples is a challenging work. In the present study, an efficient method was successfully established by macroporous resin column chromatography, medium‐pressure liquid chromatography, and high‐speed countercurrent chromatography for separation of four minor flavonoids from barley seedlings. Macroporous resin column chromatography and medium‐pressure liquid chromatography were used for enrichment of these four flavonoids. High‐pressure liquid chromatography analysis showed the total content of these four flavonoids increased from 2.2% in the crude extract to 95.3% in the medium‐pressure liquid chromatography fraction. It was indicated that the combination of macroporous resin column chromatography and medium‐pressure liquid chromatography could be a practicable strategy for enrichment of minor compounds from complex sample. Then, high‐speed countercurrent chromatography was employed for separation of these four flavonoids using ethyl acetate/n‐butanol/water (0.1% glacial acetic acid) (4:1:5, v/v/v) as solvent system. As a result, four flavonoids including two isomers with purities higher than 98% were obtained. Interestingly, two flavonoids existing in one high‐pressure liquid chromatography peak were also successfully separated. All these indicated high‐speed countercurrent chromatography had great potential for separation of compounds with similar structures and polarities. This study provides a reference for efficient enrichment and separation of minor compounds from complex sample. 相似文献
987.
Two‐dimensional (2D) organic nanomaterials are attracting increasing research interest and expected to be the ideal candidate for future‐ proofed flexible electronics and biotechnologies. Owing to the complex molecular structures and multiple intermolecular interactions in organic systems, deeper understanding of rational molecular design and assembly principles is urgently required. In this review, a collection of molecular packing mode in the 2D organic nanomaterials via supramolecular assembly is presented, so as to help explicit the relationship among molecular structures, supramolecular interactions and molecular packing motifs in 2D assembly systems. We also provide a rational and accessible schematic model to demonstrate several typical kinds of molecular packing motifs for the prediction of the 2D morphology. 相似文献
988.
Haijuan Zhi Zhenwei Li Yanping Deng Peng Qi Jinjun Hou Wen Deng Jinle Cheng Wanying Wu Dean Guo 《Biomedical chromatography : BMC》2019,33(2)
Salvia miltiorrhiza, one of the most well‐known herbal medicines, is commonly used for the treatment of coronary heart diseases in China. Besides traditional decoction slices (TDS), another relatively new product of S. miltiorrhiza, ultrafine granular powder (UGP; D90 < 45 μm), is also increasingly being used. In this paper, a UHPLC‐LTQ‐Orbitrap MS technique was developed for a metabolite profile study after oral administration of UGP and TDS of S. miltiorrhiza. The results showed that the number of in vivo absorbed compounds from UGP was much greater than that from TDS, and different types of products from S. miltiorrhiza will have different metabolic processes in vivo. Furthermore, a UHPLC‐Q‐Trap MS/MS method for simultaneously determining four tanshinones (tanshinone IIA, dihydrotanshinone I, tanshinone I and cryptotanshinone) was established and applied to assess the pharmacokinetics of the two types of products. All of the analytes displayed significant higher area under the concentration–time curve and peak concentration after oral administration of UGP than after TDS, indicating that ultrafine powder product could improve the bioavailability and absorption of cryptotanshinon,tanshinone II A,dihydrotanshinonE I and tanshinone I in vivo. The present study provides scientific information for further exploration of the pharmacology of these two types of S. miltiorrhiza and offers a reference for clinical administration of S. miltiorrhiza. 相似文献
989.
Lin‐Lin Dai Dong‐Dong Li Xiu‐Mei Zhao Shuang Zhi Hong‐Sheng Shen Zi‐Bo Yang 《Journal of heterocyclic chemistry》2019,56(2):417-425
To elevate the potency of sophoridine, phosphoramidate mustard motif was incorporated to D‐ring opened sophoridine scaffold. A series of acyclic aryloxy phosphoramidate mustard functionalized sophoridine derivatives were synthesized and screened for cytostatic activity in a range of different tumor cell lines (S180, H22, K562, MCF‐7, SMMC‐7721, and LoVo). All these compounds were shown to be more sensitive to S180 and H22 cells with IC50 values ranging from 2.10 to 7.21 μM. In addition, all targeted derivatives distinctly are more cytotoxic to cancer cells than normal cell L929. Compounds 8b , 8c , 8d , and 8e displayed moderate tumor suppression without apparent organ toxicity in vivo against mice bearing H22 liver tumors. Their potential binding modes with DNA topoisomerase I complex have also been investigated. 相似文献
990.
Prof. Dr. Jie-Ping Wan Zhi Tu Yuyun Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(28):6907-6910
A transient and recyclable C−H iodination has been designed for the synthesis of isoflavonoids through the domino reactions of o-hydroxyphenyl enaminones and aryl boronic acids in the presence of catalytic KI and Pd catalyst. Instead of the conventional cross-coupling strategy employing pre-halogenated substrates, this method transforms raw C−H bond by means of a transient C−H halogenation to smoothly relay the subsequent C-arylation. Consequently, such a method avoids the pre-functionalization for C−halogen bond installation as well as the generation of stoichiometric halogen-containing waste following the cross-coupled product, disclosing an intriguing new coupling protocol to forge the C−C bond in the virgin area between classical C−X (X=halogen) bond cross coupling and the C−H activation. 相似文献