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111.
Alfred Kreutzberger Elfriede Kreutzberger Hans-Joachim Saltler Hayriye Aml Aysel Gürsoy 《Journal of heterocyclic chemistry》1982,19(4):753-755
The three-component reaction comprising the interaction of 2-amino-4-antipyrinyl-5-ethylthiazole (1) with s-triazine (2) and pyrrolidine leads to 4-anitpyrinyl-5-ethyl-2-[(4-pyrrolidinyl)methyleneamino]thiazole (5). Structure 5 is supported by 1H- and 13C-NMR spectroscopy. 相似文献
112.
Jzsef Reiter Lszl Pong Pter Krajcsi Klra Esses-Reiter Pl Sohr Hilda Molnr Pter Dvortsk 《Journal of heterocyclic chemistry》1987,24(4):927-930
The ring-closure of the 5-amino-1-(2-aminophenyl)-3-methylthio-1H-1,2,4-triazole derivatives 3 and 4 with different simple and cyclic C1 components lead to the formation of 1,2,4-triazolo[1,5-α]-1,3,5-benzotriazepines 5–6 , their 4,5-dihydro- 7 , different 5-spiro-homocyclic- 8–13 , and 5-spiro-heterocyclic- 14-15 analogues. The structure of the compounds obtained was proved with the use of their ir, uv, 1H-nmr and 13C-nmr spectra. 相似文献
113.
This paper describes a novel approach for the surface modification of a cation-exchange membrane, bearing sulfonate groups, by a cationic layer. The modification procedure involved the chlorosulfonation of the sulfonate groups of the base membrane with thionyl chloride, followed by a reaction with a diamine to yield a sulfonamide bond and a terminal amine. The latter could be quaternized by reaction with methyl iodide or protonated by soaking in acidic media. The membranes were characterized in detail by attenuated total reflectance Fourier transform infrared and X-ray photoelectron spectroscopies as well as elemental analysis to confirm that the above reactions occurred. The selectivity of these membranes toward the electrochemically assisted transport of protons versus Zn2+ metallic cations was determined during an electrodialysis in a two-compartment electrochemical cell. The data indicate a significant decrease of the transport of the metallic cations following modification of the membrane with the cationic layer. The later allows for the transport of protons from the catholyte to the anolyte compartment with much improved selectivity since the divalent cations are excluded from the membrane due to the electrostatic barrier of the cationic layer. 相似文献
114.
A new C19 hydroxylated enyne 15, as potential A-ring building block of vitamin D analogues, was synthesized in enantiomerically pure form in nine steps from (−)-(S)-limonene. This short synthesis involved ozonolyzis of 1,2-limonene oxide followed by a Criegee rearrangement, epoxide trans diaxial ring opening by lithium acetylide, elimination, epoxidation and syn β-elimination of the resulting homopropargylic oxirane. 相似文献
115.
H. A. Ergül S. Topcuo?lu E. Ölmez Ç. K?rbaşo?lu 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(1):133-136
Summary Radionuclide (137Cs, 238U, 232Th and 40K) concentrations were determined in a sediment trap and bottom sediment samples collected from a station at the eastern Turkish
coast of the Black Sea. The specific activity of the 137Cs radionuclide in the settling particles ranged from 0.04±0.01 to 0.10±0.02 Bq. g-1dry weight. The calculated flux rate of the 137Cs was between 0.37 and 2.59 Bq. m-2. d-1in the sampling periods of 2002 and 2003. The 137Cs concentration in the bottom sediment profile were between 0.039±0.013-9.083±0.017 Bq. g-1dry weight in the same station. The vertical profile of the radionuclides suggests that they have little mobility during the
17 years after the Chernobyl accident. 相似文献
116.
The reaction of 1-(hydrazidomethyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline 3 with aromatic aldehydes yield hydrazones 4a,b or pyrimido[6,1-a]isoquinolines 5a-c depending upon the proportions of the reagents. With ketones, 3 gives only hydrazones 4a-d and 7 , which can be transformed to pyrimidoisoquinolines 10a-e and 11 with aldehydes. The ring closures are stereospecific; the relative configurations were determined by DNOE measurements. 相似文献
117.
A way of using gravity flow to induce a linear convection within a microfluidic system is presented. It is shown and mathematically supported that tilting a 1 cm long covered microchannel is enough to generate flow rates up to 1000 nL.min(-1), which represents a linear velocity of 2.4 mm.s(-1). This paper also presents a method to monitor the microfluidic events occurring in a covered microchannel when a difference of pressure is applied to force a solution to flow in said covered microchannel, thanks to electrodes inserted in the microfluidic device. Gravity-induced flow monitored electrochemically is applied to the performance of a parallel-microchannel enzyme-linked immunosorbent assay (ELISA) of the thyroid-stimulating hormone (TSH) with electrochemical detection. A simple method for generating and monitoring fluid flows is described, which can, for instance, be used for controlling parallel assays in microsystems. 相似文献
118.
119.
Darbost U Rager MN Petit S Jabin I Reinaud O 《Journal of the American Chemical Society》2005,127(23):8517-8525
The host-guest properties of calix[6]tren 1 have been evaluated. The receptor is based on a calix[6]arene that is covalently capped at the narrow rim by a tren unit. As a result, the system presents a concave hydrophobic cavity with, at its bottom, a grid-like nitrogenous core. Despite its well-defined cavity and opening to the outside at the large rim, 1 did not behave as a good receptor for neutral molecules in chloroform. However, it exhibited efficient endo-complexation of ammonium guests. By contrast, the per-protonated host, 1.4H(+), behaved as a remarkable receptor for small organic molecules. The complexation is driven by a strong charge-dipole interaction and hydrogen bonds between the polar guest and the tetracationic cap of the calixarene. Finally, coordination of Zn(2+) to the tren core led to the asymmetrization of calixarene cavity and to the strong but selective endo-binding of neutral ligands. This study emphasizes the efficiency of a receptor presenting a concave hydrophobic cavity that is polarized at its bottom. The resulting combination of charge-dipole, hydrogen bonding, CH-pi, and van der Waals interactions highly stabilizes the supramolecular architectures. Also, importantly, the tren cap allows the tuning of the polarization, offering either a basic (1), a highly charged and acidic (1.4H(+)), or a coordination (1.Zn(2+)) site. As a result, the system proved to be highly versatile, tunable, and interconvertible in solution by simple addition of protons, bases, or metal ions. 相似文献
120.
Sénèque O Rager MN Giorgi M Prangé T Tomas A Reinaud O 《Journal of the American Chemical Society》2005,127(42):14833-14840
The coordination chemistry of Zn in an N(3)ArOH environment has been explored. The ligands are based on calix[6]arenes that present two imidazole arms and an amino phenol moiety at the narrow rim. Three different types of complexes have been characterized. One is dicationic with Zn(2+) coordinated to the three nitrogen atoms and to the oxygen of the phenol group of the calix[6]ligand. This complex is very sensitive to exogenous coordinating molecules and exists as a 5-coordinate species due to the endo-complexation of a guest. The second species is a monocationic complex for which the phenol group has been deprotonated. The resulting N(3)ArOZn complex can also bind a guest ligand albeit with a lower affinity than the dicationic complex. The third species is neutral. It can be obtained upon reaction with a base to yield a hydroxo complex or with an anion such as a chloride that coordinates the metal center from the outside of the calixarene cavity. The simultaneous binding of two anionic donors decreases the Zn Lewis acidity, allowing an impressive conformational reorganization of the system. One imidazole arm is released by the metal center. The other one undergoes self-inclusion into the pi-basic calixarene cavity because the low affinity of the metal center for neutral ligand does not allow the endo-coordination of an exogenous guest. Hence, the calix[6]N(3)ArOH-based Zn complexes act as an acid-base switch for guest binding. Several aspects of this system appear reminiscent of Zn-peptidases of the astacin and serralisin families. 相似文献