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941.
The novel complex [K(18-C-6)]2[Cd(mnt)2][18-C-6-18-crown-6,nmt=1,2-dicyanoethene-1,2-dithiolate,C2S2-(CN)2^2-] was synthesized and characterized by elemental analysis,IR spectrum and X-ray diffraction analysis.The complex displays two-dimensional network structure of [K(18-C-6)] complex segments and [Cd(nmt)2] complex segment bridged by S-K-S,S-K-N and N-K-N interactions between adjacent[K(18-C-6)] and [Cd(mnt)2]units. 相似文献
942.
The techniques of oxygen electrode polarography and Fourier transform infrared (FT‐IR) spectroscopy were employed to explore the involvement of digalactosyl diacylglycerol (DGDG) in functional and structural roles in the photosystem II core complex (PSIICC). It was shown that DGDG exhibited the ability to stimulate the oxygen evolution in PSIICC, which was accompanied by the changes in the structures of PSIICC proteins. The results revealed that there existed hydrogen‐bonding interactions between DGDG molecules and PSIICC proteins. It is most likely that the sites of PSIICC interaction with DGDG are in the extrinsic protein of 33 kDa. 相似文献
943.
H. Oppermann H. Dao Quoc M. Zhang‐Preße P. Schmidt B. A. Popovkin P. S. Berdonosov V. A. Dolgikh 《无机化学与普通化学杂志》2002,628(4):891-895
Investigations on the System SmOCl/SeO2 The existence of three ternary phases SmSeO3Cl, SmSe2−O5Cl, and SmSe3O7Cl is shown on the quasibinary line SmOClSeO2. The phase barogram and the phase diagram are determined by total pressure measurements and DTA, respectively. SmSe3O7Cl melts peritectical at 340 ± 10 °C, SmSe2O5Cl melts peritectical at 560 ± 10 °C while SmSeO3Cl shows no thermal effects up to 900 °C The data of enthalpies and entropies of the phases are evaluated from the total pressure measurements (Data see „Inhaltsübersicht”︁) 相似文献
944.
945.
946.
947.
A new polymerization strategy, consisting of nucleophilic substitution reaction between CS32‐, immobilized on a polymeric support, and dimethyl α,α′‐dibromoalkylanedioate in solution, leads to the formation of polytrithiocarbonates. When n = 0, 1 in CH3OOCCHBr(CH2)nCHBrCOOCH3 (α,α′‐dibromoalkylanedioate), only five‐ or six‐membered cyclic trithiocarbonates were obtained; n ≥ 2 resulted in the formation of polytrithiocarbonates. 相似文献
948.
Agnes Taillardat‐Bertschinger Francesco Barbato MariaTiziana Quercia Pierre‐Alain Carrupt Marianne Reist MariaI. LaRotonda Bernard Testa 《Helvetica chimica acta》2002,85(2):519-532
The aims of this study were to investigate whether three commercially available immobilized artificial membrane (IAM) HPLC columns yield collinear data for neutral compounds, and whether IAM scales are distinct from the log Poct (partition coefficient in the octanol/H2O system) scale. With these objectives, the retention mechanisms on the IAM HPLC columns were analysed by linear solvation free‐energy relationships (LSERs). A set of 68 neutral model compounds with known solvatochromic parameters and log Poct values was investigated, allowing a regular and broad exploration of property space. The resulting solvatochromic equations clearly indicate that the three IAM stationary phases retain small neutral solutes by a balance of intermolecular forces closely resembling those underlying partitioning in octanol/H2O and retention on a reversed‐phase LC‐ABZ HPLC column. For all systems, the solute's size and hydrogen‐bond‐acceptor basicity are the two predominant factors, whereas dipolarity/polarisability and hydrogen‐bond‐donor acidity play only minor roles. 相似文献
949.
Atta‐ur‐Rahman Zaheer‐ul‐Haq Asaad Khalid Shazia Anjum M.Riaz Khan M.Iqbal Choudhary 《Helvetica chimica acta》2002,85(2):678-688
Phytochemical investigation of Sarcococca saligna by extensive bioassay‐guided fractionation resulted in the isolation of the pregnane‐type steroidal alkaloids 1 – 15 , i.e. of the five new compounds 1 – 5 and the ten known alkaloids 6 – 15 . The structures of the new alkaloids salignenamide C ( 1 ), salignenamide D ( 2 ), 2β‐hydroxyepipachysamine D ( 3 ), salignenamide E ( 4 ), and salignenamide F ( 5 ) were elucidated with the help of modern spectroscopic techniques, while the known alkaloids axillarine C ( 6 ), axillarine F ( 7 ), sarcorine ( 8 ), N3‐demethylsaracodine ( 9 ), saligcinnamide ( 10 ), salignenamide A ( 11 ), vaganine A ( 12 ), axillaridine A ( 13 ), sarsalignone ( 14 ), and sarsalignenone ( 15 ) were identified by comparing their spectral data with those reported earlier. Inhibition of electric‐eel acetylcholinesterase (EC 3.1.1.7) and horse‐serum butyrylcholinesterase (EC 3.1.1.8) by alkaloids 1 – 15 were investigated. These new cholinesterase inhibitors may act as potential leads in the discovery of clinically useful inhibitors for nervous‐system disorders, particularly by reducing memory deficiency in Alzheimer's disease patients by potentiating and effecting the cholinergic transmission process. These compounds were found to inhibit both enzymes in a concentration‐dependent fashion with the IC50 values ranging from 5.21–227.92 μM against acetylcholinesterase and 2.18–38.36 μM against butyrylcholinesterase. 相似文献
950.
DmitriV. Sevenard OlegG. Khomutov KazimirI. Pashkevich Enno Lork Gerd‐Volker Rschenthaler 《Helvetica chimica acta》2002,85(7):1960-1972
The 2‐acylcycloalkanones 1a – g and 3a – c , possessing a polyfluoroalkyl group, react with hydroxylamine regio‐ and stereoselectively to yield 4,5‐dihydroisoxazol‐5‐ols 2a – g and 4a – c , respectively, i.e., products of N‐addition to the oxo group at the cycloalkane ring (Schemes 1 and 2). The products 2 and 4 can be dehydrated under drastic conditions only (Schemes 3 and 4). The structure of one of the 4,5‐dihydroisoxazol‐5‐ols was confirmed by X‐ray crystal‐structure analysis. 相似文献