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991.
A synergistic N doping plus PO43? intercalation strategy is used to induce high conversion (ca. 41 %) of 2H‐MoS2 into 1T‐MoS2, which is much higher than single N doping (ca. 28 %) or single PO43? intercalation (ca. 10 %). A scattering mechanism is proposed to illustrate the synergistic phase transformation from the 2H to the 1T phase, which was confirmed by synchrotron radiation and spherical aberration TEM. To further enhance reaction kinetics, the designed (N,PO43?)‐MoS2 nanosheets are combined with conductive vertical graphene (VG) skeleton forming binder‐free arrays for high‐efficiency hydrogen evolution reaction (HER). Owing to the decreased band gap, lower d‐band center, and smaller hydrogen adsorption/desorption energy, the designed (N,PO43?)‐MoS2/VG electrode shows excellent HER performance with a lower Tafel slope and overpotential than N‐MoS2/VG, PO43?‐MoS2/VG counterparts, and other Mo‐base catalysts in the literature.  相似文献   
992.
Aggregated β‐amyloid (Aβ) is widely considered as a key factor in triggering progressive loss of neuronal function in Alzheimer's disease (AD), so targeting and inhibiting Aβ aggregation has been broadly recognized as an efficient therapeutic strategy for curing AD. Herein, we designed and prepared an organic platinum‐substituted polyoxometalate, (Me4N)3[PW11O40(SiC3H6NH2)2PtCl2] (abbreviated as PtII‐PW11) for inhibiting Aβ42 aggregation. The mechanism of inhibition on Aβ42 aggregation by PtII‐PW11 was attributed to the multiple interactions of PtII‐PW11 with Aβ42 including coordination interaction of Pt2+ in PtII‐PW11 with amino group in Aβ42, electrostatic attraction, hydrogen bonding and van der Waals force. In cell‐based assay, PtII‐PW11 displayed remarkable neuroprotective effect for Aβ42 aggregation‐induced cytotoxicity, leading to increase of cell viability from 49 % to 67 % at a dosage of 8 μm . More importantly, the PtII‐PW11 greatly reduced Aβ deposition and rescued memory loss in APP/PS1 transgenic AD model mice without noticeable cytotoxicity, demonstrating its potential as drugs for AD treatment.  相似文献   
993.
The fundamental understanding and rational manipulation of catalytic site preference at extended solid surfaces is crucial in the search for advanced catalysts. Herein we find that the Ru top sites at metallic ruthenium surface have efficient Pt‐like activity for the hydrogen evolution reaction (HER), but they are subordinate to their adjacent, less active Ru3‐hollow sites due to the stronger hydrogen‐binding ability of the latter. We also present an interstitial incorporation strategy for the promotion of the Ru top sites from subordinate to dominant character, while maintaining Pt‐like catalytic activity. Our combined theoretical and experimental studies further identify intermetallic RuSi as a highly active, non‐Pt material for catalyzing the HER, because of its suitable electronic structure governed by a good balance of ligand and strain effects.  相似文献   
994.
The marine fungus Emericella sp was isolated from the deep sea sediments. The fungus was identified by its morphology and ITS region. A new emerixanthone E (1) together with four (2–5) known emodin derivatives were isolated from the metabolites of the fungus Emericella SCSIO05240. The structures were elucidated on the basis of NMR spectroscopic analysis and mass spectrometry. The biological properties of those compounds (1–5) were explored for antimicrobial, antifungal and antitumor activity.  相似文献   
995.
Through regulating the pH values, a series of iodo‐argentate/cuprate hybrids, [Me3(4‐TPT)]4[Ag6I18] ( 1 , Me3(4‐TPT)=N,N′,N′′‐trimethyl‐2,4,6‐tris(4‐pyridyl)‐1,3,5‐triazine), [Me3(4‐TPT)][M5I8] (M=Ag/ 2 , Cu/ 2 a ), [Me3(3‐TPT)][M5I8] (Me3(3‐TPT)=N,N′,N′′‐trimethyl‐2,4,6‐tris(3‐pyridyl)‐1,3,5‐triazine, M=Ag/ 3 , Cu/ 4 ), which exhibit adjustable structural variations with different dimensional structures, have been obtained under solvothermal conditions. They are directed by two types of in situ N‐alkylation TPT‐derivatives (Me3(4‐TPT) for 1 / 2 / 2 a and Me3(3‐TPT) for 3 / 4 ) and represent the isolated units ( 1 ), 1D polymeric chain ( 4 ), 2D layered structures ( 2 / 2 a , 3 ) based on diverse metal iodide clusters. These compounds possess reducing band gaps as compared with the bulk β‐AgI and CuI and belong to potential semiconductor materials. Iodocuprates feature highly efficient photocatalytic activity in the sunlight‐induced degradation of organic dyes. The detailed study on the possible photocatalytic mechanism, including radical trapping tests and theoretical calculations, reveals that the N‐alkylation TPT moieties contribute to the narrow semiconducting behavior and effectively inhibit the recombination of photogenerated electron‐hole pairs, which result in an excellent visible‐light‐induced photocatalytic performance.  相似文献   
996.
The short, efficient total synthesis of (+)‐aquatolide was achieved by a biomimetic transannular [2+2] photocycloaddition, and provides the first example of constructing a 5/5/4/8‐ring system from asteriscunolides. Furthermore, the reaction leading to a 5/4/4/7‐ring system, the originally proposed structure of aquatolide, was also developed. This strategy achieved syntheses of five more humulanolides, (?)‐asteriscunolides A, C, D, and I, and (+)‐tetradehydroasteriscanolide.  相似文献   
997.
A nondestructive parity‐check detector (PCD) scheme for two single‐electron quantum dots embedded in double‐sided optical microcavities is presented here. Using a polarization‐entangled photon pair, the PCD works in a parallel style and is robust to the phase fluctuation of the optical path length. In addition, based on this nondestructive PCD, an economic entanglement purification protocol for electron pairs is presented. The parties in quantum communication can increase the purification efficiency and simultaneously decrease the quantum source consumed for some particular fidelity thresholds. Therefore, this protocol has good applications in the future quantum communication and distributed quantum networks.  相似文献   
998.
外周血中单个网织红细胞与小淋巴细胞的拉曼光谱   总被引:4,自引:1,他引:3  
为了在外周血中准确区分大小相近的网织红细胞和小淋巴细胞,采用光镊与拉曼光谱结合的单细胞技术.研究发现大鼠血液中单个网织红细胞和小淋巴细胞的光谱形态相差很大,主要体现在以下位置:1212,1548,1607,1616,1001,1661 cm-1(以上与蛋白质相关),1584 cm-1(与核酸相关).通过分析部分特征峰.证明小淋巴细胞相对于网织红细胞而言,所含有的核酸含量高,蛋白质含量少.通过主成分分析和判别分析两种统计方法进行分析,均可完全区分这两种细胞.通过上述分析,得到厂一种光谱学上快速、准确地区分外周血中网织红细胞和小淋巴细胞的方法,同时也为在现代生物医学研究血细胞提供一种识别依据和手段.  相似文献   
999.
1000.
一种新的Fabry-Perot干涉条纹处理方法   总被引:1,自引:0,他引:1  
介绍了一种提取Fabry-Perot(法布里-帕罗)干涉条纹圆心点坐标和条纹半径的新方法。首先对干涉图像依次进行二值化处理,对所得到的条纹强度曲线进行均平滤波和自适应滤波,根据条纹灰度值强度余弦函数分布的特点,对条纹灰度值数据进行最小二乘法拟合,获得条纹强度峰值坐标,通过精确的迭代算法,进而获得Fabry-Perot干涉条纹圆心点的坐标;然后再对干涉条纹进行圆周积分,从而可以确定每级Fabry-Perot干涉条纹的半径长度。该方法可提高计算精度,减小计算误差。  相似文献   
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