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991.
Four Metal Complexes Based on Bulky Imidazole Ligands: Solvothermal Syntheses,Crystal Structures,and Fluorescence Properties
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Xue Zhang Sai Li Yue‐Jiao He Tong Han Xiao‐Ling Wang Bang Chen Kang‐Yu Zou Zuo‐Xi Li 《无机化学与普通化学杂志》2015,641(11):1874-1880
In order to explore the influences of (de‐)protonation of the imidazole ring on the structural diversity of the resulting complexes, the imidazole‐based ligands 4, 5‐diphenylimidazole (Hdpi) and 1H‐phenanthro[9, 10‐d]imidazole (Hpi) were utilized as bulky building blocks to construct four complexes by solvothermal reactions, i.e. [Ag(Hdpi)2](NO3) · (H2O) ( 1 ), [Cu(dpi)]∞ ( 2 ), [Cu(Hpi)(NO3)]∞ ( 3 ), and [(H2pi)(NO3)] · H2O ( 4 ). In complex 1 , two Hdpi ligands adopt a monodentate pattern and coordinate with one AgI ion to form a mononuclear unit, which is further connected by hydrogen bonds into a 1D supramolecular helix. The deprotonated dpi ligand of 2 acts in bidentate mode, and bridges CuI ions to afford a 1D chain. In 3 , the NO3– ion, acts as a monodentate bridging ligand and joins CuI ions to generate a 1D chain. The Hpi ligand employs a monodentate mode to bond with CuI ions of the 1D chain. 4 is protonated and two H2pi nitrogen atoms are free of coordination. Interestingly, hydrogen bonds among the NO3– ion, the H2pi ligand, and the water molecule yield a macro ring R44(14). The resulting structural diversity reveals that the (de‐)protonation of imidazole ring directly steers the coordination number of ligand, and thus causes a significant effect on the structure, especially the dimensionality. Furthermore, the solid‐state fluorescence properties of the free ligands and compounds 1 – 4 were studied at room temperature. 相似文献
992.
Xing‐Ye Mu Chao Li Yu‐Ling Li Yun Liu Xiang‐Shan Wang 《Journal of heterocyclic chemistry》2015,52(2):373-379
A three‐component reaction between an aromatic aldehyde, quinolin‐6‐amine or quinolin‐5‐amine, and tert‐butyl 2,4‐dioxopiperidine‐1‐carboxylate in reflux EtOH gave pyrido phenanthroline derivatives in high yields under catalyst free conditions. The rare C‐H…F hydrogen bond is found in the crystal structure of 6h . 相似文献
993.
994.
995.
Application of a multivariate approach for analyte focusing by micelle collapse‐micellar electrokinetic chromatography for analyzing sunscreen agents in cosmetics
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Yi‐Hui Lin Chi‐Yu Lu Shiuh‐Jen Jiang Wen‐Yao Hsiao Hui‐Ling Cheng Yen‐Ling Chen 《Electrophoresis》2015,36(19):2396-2403
The operating parameters that affect the performance of the online preconcentration technique “analyte focusing by micelle collapse‐MEKC (AFMC‐MEKC)” were examined using a multivariate approach involving experimental design to determine the sunscreen agents in cosmetics. Compared to the single‐variable approach, the advantage of the multivariate approach was that many factors could be investigated simultaneously to obtain the best separation condition. A fractional factorial design was used to identify the fewest significant factors in the central composite design (cCD). The cCD was adopted for evaluating the location of the minimum or maximum response in this study. The influences of the experimental variables on the response were investigated by applying a chromatographic exponential function. The optimized condition and the relationship between the experimental variables were acquired using the JMP software. The ANOVA analysis indicated that the Tris pH value, SDS concentration, and ethanol percentage influenced the separation quality and significantly contributed to the model. The optimized condition of the running buffer was 10 mM Tris buffer (pH 9.5) containing 60 mM SDS, 7 mM γ‐CD, and 20% v/v ethanol. The sample was prepared in 100 mM Tris buffer (pH 9.0) containing 7.5 mM SDS and 20% v/v ethanol. The SDS concentration in the sample matrix was slightly greater than the CMC value that makes the micelle be easily collapsed and the analytes be accumulated in the capillary. In addition, sunscreen agents in cosmetics after 1000‐fold dilution were successfully determined by AFMC‐MEKC. 相似文献
996.
以巯基乙酸甲酯(MT)修饰的纳米金(AuNPs)为探针,构建了比色生物传感器检测脂肪酶活性.在pH 6.5弱酸性条件下,脂肪酶水解MT-AuNPs上的酯键生成带负电荷的羧酸根;在pH 3.0的酸性条件下,探针间会产生强烈的氢键作用使AuNPs聚集,基于此可以检测脂肪酶活性.考察了温度、pH等因素对传感器响应信号的影响.MT-AuNPs溶液在650和520 nm处的吸光度比值A650/A520与脂肪酶活性大小在3.0×10-4 ~4.5 ×10-2 U/mL范围内呈现良好的线性关系,检出限为2.25×10-4 U/mL(S/N=3).测定了5种商品化脂肪酶的活性,实验结果与恒电位滴定法测定结果一致,证明本方法具有良好的实用性. 相似文献
997.
Jing‐Mei Bao Min‐Hong Jiang Shu‐Ling Lin Zhi‐You Su Gui‐Hua Tang Sheng Yin 《Helvetica chimica acta》2015,98(10):1387-1394
Five new cassane diterpenoids, caesalmins I–M ( 1 – 5 ), and 23 known analogs were isolated from the seeds of Caesalpinia minax. Their structures were elucidated by spectroscopic methods and comparison with reported data. The antioxidant properties of 1 – 28 were determined by the method of oxygen radical absorbance capacity of fluorescein (ORAC‐FL), and 14 compounds exhibited good antioxidant activities with ORAC‐FL values of 2.24–4.89 Trolox equivalents. The structure? activity relationship of the active compounds was also discussed. 相似文献
998.
Ya‐Zhu Zhu Yan‐Hong Li Dan Liu Ling‐Huan Gao Hong‐Mei Li Rong‐Tao Li 《Helvetica chimica acta》2015,98(8):1132-1140
Four new iridoids, incarvoids D–F ( 1 – 3 , resp.) and incarvoid B 9‐O‐β‐D ‐glucopyranoside ( 4 ), and one new monoterpenoid, argutoid B ( 5 ), along with 14 known compounds, were isolated from Rhododendron microphyton. Their structures were established by comprehensive 1D‐ and 2D‐NMR spectroscopic analysis. 相似文献
999.
Paecilomycines A and B,Novel Diterpenoids,Isolated from Insect‐Pathogenic Fungi Paecilomyces sp. ACCC 37762
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Kun Zhou Xiao‐Ling Zhao Li‐Ping Han Meng‐Meng Cao Chuan Chen Bao‐Zhong Shi Du‐Qiang Luo 《Helvetica chimica acta》2015,98(5):642-649
Two new diterpenoids, named paecilomycine A ( 1 ) and paecilomycine B ( 2 ), including a novel skeleton with a five‐membered lactone ring, together with three known labdane diterpenoids, rel‐(1R,3S,4aS,5R,8aS)‐5‐[(3E)‐4‐carboxy‐3‐methylbut‐3‐en‐1‐yl]decahydro‐3‐hydroxy‐1,4a‐dimethyl‐6‐methylidenenaphthalene‐1‐carboxylic acid ( 3 ), botryosphaerin E ( 4 ), and agathic acid ( 5 ), were isolated from solid culture of the insect pathogenic fungi strain Paecilomyces sp. The structures of all compounds were established on the basis of comprehensive spectroscopic studies. The relative configurations of 1 and 2 were determined by single‐crystal X‐ray diffraction analyses. 相似文献