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981.
982.
983.
A simple and rapid micellar electrokinetic chromatography (MEKC) method with UV detection was developed for the simultaneous separation and determination of all-trans- and 13-cis-retinoic acids in rabbit serum by on-line sweeping concentration technique. The serum sample was simply deproteinized and centrifuged. Various parameters affecting sample enrichment and separation were systematically investigated. Under optimal conditions, the analytes could be well separated within 17min, and the relative standard deviations (RSD) of migration times and peak areas were less than 3.4%. Compared with the conventional MEKC injection method, the 18- and 19-fold improvements in sensitivity were achieved, respectively. The proposed method has been successfully applied to the determination of all-trans- and 13-cis-retinoic acids in serum samples from rabbits and could be feasible for the further pharmacokinetics study of all-trans-retinoic acid. 相似文献
984.
Efficient Visible‐Light‐Driven Carbon Dioxide Reduction by a Single‐Atom Implanted Metal–Organic Framework 下载免费PDF全文
Dr. Huabin Zhang Dr. Jing Wei Dr. Juncai Dong Dr. Guigao Liu Li Shi Dr. Pengfei An Dr. Guixia Zhao Dr. Jintao Kong Dr. Xiaojun Wang Dr. Xianguang Meng Prof. Jing Zhang Prof. Jinhua Ye 《Angewandte Chemie (International ed. in English)》2016,55(46):14310-14314
Modular optimization of metal–organic frameworks (MOFs) was realized by incorporation of coordinatively unsaturated single atoms in a MOF matrix. The newly developed MOF can selectively capture and photoreduce CO2 with high efficiency under visible‐light irradiation. Mechanistic investigation reveals that the presence of single Co atoms in the MOF can greatly boost the electron–hole separation efficiency in porphyrin units. Directional migration of photogenerated excitons from porphyrin to catalytic Co centers was witnessed, thereby achieving supply of long‐lived electrons for the reduction of CO2 molecules adsorbed on Co centers. As a direct result, porphyrin MOF comprising atomically dispersed catalytic centers exhibits significantly enhanced photocatalytic conversion of CO2, which is equivalent to a 3.13‐fold improvement in CO evolution rate (200.6 μmol g?1 h?1) and a 5.93‐fold enhancement in CH4 generation rate (36.67 μmol g?1 h?1) compared to the parent MOF. 相似文献
985.
Turn‐On Colorimetric Platform for Dual Activity Detection of Acid and Alkaline Phosphatase in Human Whole Blood 下载免费PDF全文
Dr. Qiong Hu Dr. Baojing Zhou Prof. Dr. Feng Li Prof. Dr. Jinming Kong Prof. Dr. Xueji Zhang 《化学:亚洲杂志》2016,11(21):3040-3045
The activity detection of acid phosphatase (ACP) and alkaline phosphatase (ALP) is of great importance to the diagnosis and prognosis of related diseases. In this work, we report for the first time a turn‐on colorimetric platform for the activity detection of ACP and ALP, by exploiting Cu(BCDS)22? (BCDS=bathocuproinedisulfonate) as the probe. The presence of ACP or ALP dephosphorylates the substrate ascorbic acid 2‐phosphate to produce ascorbic acid, which then reduces Cu(BCDS)22? into Cu(BCDS)23?, leading to a turn‐on spectral absorption at 484 nm and a dramatic color change of the solution from colorless to orange‐red. The underlying metal‐to‐ligand charge‐transfer mechanism has been demonstrated by quantum mechanical computations. This platform allows a rapid, sensitive readout of ACP and ALP activities within the dynamic range from 0 to 220 mU ml?1. In addition, it is highly immune to false‐positive results and also highly selective. More importantly, it is applicable in the presence of human serum and even whole blood samples. These results demonstrate that our platform holds great potential in clinical practices and in the point‐of‐care analysis. 相似文献
986.
LC/MS3‐Guided biotransformation of p‐coumaric acid (=(2E)‐3‐(4‐hydroxyphenyl)prop‐2‐enoic acid; CA) with H2O2/Momordica charantia peroxidase at pH 5.0 and 45° in the presence of acetone has resulted in the isolation of three CA trimers, triCA1 ( 1 ), triCA2 (trans‐ 2 ), and triCA3 (cis‐ 2 ), and seven CA dimers, diCA1–diCA7, i.e., 3 – 9 , among which seven (triCA1–triCA3 and diCA1–diCA4) are new compounds and three (diCA5–diCA7) are known compounds. The structures were established by 2D‐NMR such as HSQC, HMBC, and NOESY measurements. The possible mechanism for the formation of the products is also discussed (Schemes 1–3). This is the first time that the biotansformation of p‐coumaric acid catalyzed by peroxidase in vitro was achieved. Compounds triCA3 (cis‐ 2 ), diCA1 ( 3 ), diCA5 ( 7 ), and diCA7 ( 9 ) exhibit a stronger antioxidative activity than the parent CA. 相似文献
987.
Qian Chu Ling‐Yan Kong Taka‐aki Okamura Hiroyuki Kawaguchi Wen‐Li Meng Wei‐Yin Sun Prof. Dr. Norikazu Ueyama 《无机化学与普通化学杂志》2007,633(2):326-331
Assembly of bidentate ligand 1‐(1‐imidazolyl)‐4‐(imidazol‐1‐ylmethyl)benzene (IIMB) with varied metal salts of ZnII, CdII and PbII provide three new complexes, [Zn(IIMB)2](ClO4)2·2H2O ( 1 ), [Cd(IIMB)2(SCN)2] ( 2 ) and [Pb(IIMB)2(SCN)](SCN) ( 3 ). Single crystal X‐ray diffraction studies revealed that complexes 1 and 2 display a similar one‐dimensional double stranded chain structure, while complex 3 is a slight distorted rhombohedral grid network with (4,4) topology. The results indicate that the coordination geometry of the metal ion and the counter anion have great impact on the structure of the complexes. In addition, the photoluminescence properties of ligand IIMB and complexes 1 – 3 were studied in the solid state at room temperature. 相似文献
988.
Qiao CF Han QB Song JZ Mo SF Kong LD Kung HF Xu HX 《Journal of separation science》2007,30(6):813-818
Fructus Psoraleae, a widely used traditional Chinese medicine, is well known as a health supplement ingredient. In our study, an improved and comprehensive HPLC fingerprint of Fructus Psoraleae was established. Two important new benzofuran glycosides, psoralenoside and isopsoralenoside, were identified as characteristic constituents for the first time. HPLC separation was performed on an RP-C8 column. The mobile phase was acetonitrile and 0.1% acetic acid solution with linear gradient change of acetonitrile from 10 to 82% in 40 min. The flow rate was 1.0 mL/min, and the detection wavelength was set at 310 nm. The HPLC chromatograms of twenty-six samples from different regions of China showed a similar pattern. Twelve peaks were selected as characteristic peaks and further identified as psoralenoside, isopsoralenoside, psoralen, isopsoralen, bavachromene, corylifolin, corylin, psoralidin, isobavachalcone, bavachinin, corylifol A, and bakuchiol, respectively. Nine of them were simultaneously quantitatively analyzed for the first time. A more comprehensive analytical method was established for the fingerprint of Fructus Psoraleae. It is very useful for authentication and quality assessment of the crude drug. 相似文献
989.
Hongyan Zhang Lingqian Kong Daopeng Zhang 《Russian Journal of Inorganic Chemistry》2016,61(7):841-845
A new one-dimensional Schiff-base ligand bridged manganese(III) complex with the formula [Mn(acacen)(H2acacen)]ClO4 (1) (acacen = N, N'-ethylenebis(acetylacetonylideneaminato) has been obtained from the reaction of [Mn(acacen)(H2O)2]ClO4 with K[Fe(bpdBrb)(CN)2] (bpdBrb2– = 1,2-bis(pyridine-2-carboxamido)-4,5-dibromobenzenate), which has been characterized by elemental analysis, IR spectroscopy and X-ray structure determination. Single X-ray diffraction analysis reveals it’s onedimensional infinite structure consisting of alternating units of [Mn(acacen)]+ and the Schiff-base ligand H2acacen with a trans conformation, forming a cationic polymeric chain with free ClO4- as the balanced anion. The one-dimensional chain structure can be can be further linked into three-dimensional supramolecular network under the help of the intermolecular weak interactions. Investigation over its magnetic property reveals the weak antiferromagnetic coupling between the adjacent Mn(III) ions. 相似文献
990.
A combined DFT quantum mechanical and AMBER molecular mechanical potential (QM/MM) is presented for use in molecular modeling and molecular simulations of large biological systems. In our approach we evaluate Lennard-Jones parameters describing the interaction between the quantum mechanical (QM) part of a system, which is described at the B3LYP/6-31+G* level of theory, and the molecular mechanical (MM) part of the system, described by the AMBER force field. The Lennard-Jones parameters for this potential are obtained by calculating hydrogen bond energies and hydrogen bond geometries for a large set of bimolecular systems, in which one hydrogen bond monomer is described quantum mechanically and the other is treated molecular mechanically. We have investigated more than 100 different bimolecular systems, finding very good agreement between hydrogen bond energies and geometries obtained from the combined QM/MM calculations and results obtained at the QM level of theory, especially with respect to geometry. Therefore, based on the Lennard-Jones parameters obtained in our study, we anticipate that the B3LYP/6-31+G*/AMBER potential will be a precise tool to explore intermolecular interactions inside a protein environment. 相似文献