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901.
Yong Nie Chun‐Hua Hu Xue Li Wei Yong Jian‐Min Dou Jie Sun Ruo‐Shui Jin Pei‐Ju Zheng 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(8):897-899
Each of the title compounds, 8‐methoxy‐7,7‐bis(triphenylphosphine‐P)‐8,9:10,11‐di‐μH‐7‐platina‐nido‐undecaborane dichloromethane hemisolvate, [Pt(CH14B10O)(C18H15P)2]·0.5CH2Cl2, (I), 8‐isopropoxy‐7,7‐bis(triphenylphosphine‐P)‐8,9:10,11‐di‐μH‐7‐platina‐nido‐undecaborane dichloromethane solvate, [Pt(C3H18B10O)(C18H15P)2]·CH2Cl2, (II), and 9‐isopropoxy‐7,7‐bis(triphenylphosphine‐P)‐8,9:10,11‐di‐μH‐7‐platina‐nido‐undecaborane dichloromethane solvate, [Pt(C3H18B10O)(C18H15P)2]·CH2Cl2, (III), has an 11‐vertex nido polyhedral skeleton, with the 7‐platinum centre ligating to two exo‐polyhedral PPh3 groups and an alkoxy‐substituted polyhedral borane ligand. Compounds (II) and (III) are isomers. The Pt—B distances are in the range 2.214 (7)–2.303 (7) Å for (I), 2.178 (16)–2.326 (16) Å for (II) and 2.205 (6)–2.327 (6) Å for (III). 相似文献
902.
The reaction of CuCl2 · 2 H2O, 1,10‐phenanthroline (phen), suberic acid and Na2CO3 in a CH3CN–H2O solution yielded blue needle‐like crystals of [Cu2(phen)2(C8H12O4)2] · 3 H2O. The crystal structure (monoclinic, P21/n, a = 10.756(2) Å, b = 9.790(2) Å, c = 18.593(4) Å, β = 91.15(3)°, Z = 2, R = 0.043, wR2 = 0.1238) consists of suberato‐bridged [Cu2(phen)2(C8H12O4)4/2] layers and hydrogen bonded H2O molecules. The Cu atoms are coordinated by two N atoms from one bidentate chelating phen ligand and three carboxyl O atoms from different suberato ligands to form distorted [CuN2O3] square‐pyramids with one carboxyl O atom at the apical position (d(Cu–N) = 2.017(2), 2.043(3) Å, basal d(Cu–O) = 1.936(2), 1.951(2) Å and axial d(Cu–O) = 2.389(2) Å). Two [CuN2O3] square‐pyramids are condensed via a common O–O edge to a centrosymmetric [Cu2N4O4] dimer with the Cu…Cu distance of 3.406(1) Å indicating no interaction between Cu atoms. The resultant [Cu2N4O4] dimers are interlinked by the tridentate suberato ligands to form [Cu2(phen)2(C8H12O4)4/2] layers parallel to (101). These are assembled via π‐π stacking interactions into 3D network with H2O molecules in the tunnels extending in the [010] direction. 相似文献
903.
Yang M Wang X Guan S Xia J Sun J Guo H Guo DA 《Journal of the American Society for Mass Spectrometry》2007,18(5):927-939
Triterpenoids extracted from Ganoderma lucidum (Leyss. ex Fr.) Karst were separated and characterized using optimized reversed-phase liquid chromatography with diode array detection and electrospray ion trap tandem mass spectrometry (HPLC-DAD-ESI-MS(n)). They could be classified into five types depending on the fragmentation behavior. All triterpenoids gave [M - H](-) and [2M - H](-) ions by electrospray ionization monitored in the negative ion mode; in addition, compounds of types III and IV gave prominent [M - H - H(2)O](-) ions and the unsaturated bond at C-20, 22 would reduce the abundance of [M - H - H(2)O](-) ion. The key fragmentation information was cleavage at C- and D-rings despite the predominant losses of H(2)O and CO(2). Compounds with hydroxyls at C-7 and C-15 would produce a list of b, b - 1, b - 2, and b - 16 ions attributed to cleavage of D-ring; if the second alcohol at C-15 were oxidized to ketone, the prominent cleavage would occur at C-ring and produce a group of ions of a; if C-7 were oxidized to ketone, transference of two hydrogen atoms would occur during the cleavage of rings and a list of ions about a + 2 and/or b + 2 would appear instead. The above fragmentations and regularities in fragmentation pathways were reported for the first time, and were implemented for the analysis of triterpenoids in G. lucidum. The chloroform extract was separated on a Zorbax SB-C(18) column, eluting with an acetonitrile-0.2% acetic acid gradient. A total of 32 triterpenoids, including six new ones, were identified or tentatively characterized based on the tandem mass spectra of the HPLC peaks. 相似文献
904.
905.
Two rapid,sensitive and reliable immunoassay methods,namely competitive indirect enzyme-linked immunosorbent assay(CI- ELISA)and colloidal gold-based immunochromatographic assay(CGIA),were developed to detect ofloxacin(OFL).The linear range of the CI-ELISAwas from 0.5 to 128 ng/mL with a limit of detection(LOD)of 0.35 ng/mL.Good recoveries were obtained in analyzing simulated swine urine samples.The CGIA could accurately estimate OFL at concentrations as low as 10 ng/mL in less than 10 min,and test results were read visually without any instrument. 相似文献
906.
采用电沉积-热解法在3Cr25Ni7N合金表面制备了Y2O3薄膜,并研究了薄膜处理对合金在1000℃空气中的抗高温氧化性能的影响。氧化动力学曲线、SEM及XRD分析结果表明,Y2O3薄膜处理使合金表面氧化膜以尖晶石结构为主,氧化膜致密,有效地抑制了Cr2O3的挥发反应,且氧化膜与基体的附着性好,因此合金在高温下的抗氧化性能得到提高,这与氧化钇薄膜在较低温度下抗高温氧化性能提高的机制是不同的。在不同温度下,Y2O3薄膜处理均可以有效提高合金的抗高温氧化性能。 相似文献
907.
Kou X Zhang S Tsung CK Yang Z Yeung MH Stucky GD Sun L Wang J Yan C 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(10):2929-2936
Gold nanorods were prepared in high yields by using a one-step seed-mediated process in aqueous cetyltripropylammonium bromide (CTPAB) and cetyltributylammonium bromide (CTBAB) solutions in the presence of silver nitrate. The diameters of the nanorods range from 3 to 11 nm, their lengths are in the range of 15 to 350 nm, and their aspect ratios are in the range of 2 to 70. The diameters of the Au nanorods obtained from one growth batch in CTPAB solutions decrease as their lengths increase, and their volumes decrease as the aspect ratios increase. The diameters of the Au nanorods obtained from one growth batch in CTBAB solutions first decrease and then slightly increase as their lengths increase, and their volumes increase as the aspect ratios increase. These Au nanorods are single-crystalline and are seen to be oriented in either the [100] or [110] direction under transmission electron microscopy imaging, irrespective of their sizes. To the best of our knowledge, this is the first report of the preparation by using wet-chemistry methods of single-crystalline Au nanorods with aspect ratios larger than 15. 相似文献
908.
Han F Bao Y Yang Z Fyles TM Zhao J Peng X Fan J Wu Y Sun S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(10):2880-2892
Bis-thiocarbono-hydrazones are found to be a class of sensitive, selective, ratiometric, and colorimetric chemosensors for anions such as fluoride (F(-)) or acetate (Ac(-)). The sensitivities, or the binding constants of the sensors with anions, were found to be strongly dependent on the substituents appended on the pi-conjugation framework, the delocalization bridge CH==N, the aromatic moiety, and the hetero atom in the C==X group (X=O, S) of the sensors. Single-crystal structures and (1)H NMR titration analysis shows that the --CH==N-- moiety is a hydrogen-bond donor, and it is proposed that an additional CHF hydrogen bond is formed for the sensors in the presence F(-). A sensor bearing anthracenyl groups is demonstrated as a switch-on fluorescent chemosensor for F(-) and Ac(-). The recognition of F(-) in acetonitrile (MeCN) by a sensor with nitrophenyl substituents is tolerant to MeOH (MeCN/MeOH=10:1, v/v) and water (MeCN/H(2)O=30:1, v/v); at these solvent ratios the absorption intensity of the sensor-F(-) complex solution at maximal absorption wavelength was attenuated to half of the original value in pure MeCN. 相似文献
909.
910.
On the basis of the isoelectric point of an enzyme and the doping principle of conducting polymers, choline oxidase was doped
in a polyaniline film to form a biosensor. The amperometric detection of choline is based on the oxidation of the H2O2 enzymatically produced on the choline biosensor. The response current of the biosensor as a function of temperature was determined
from 3 to 40°C. An apparent activation energy of 22.8 kJ·mol−1 was obtained. The biosensor had a wide linear response range from 5 × 10−7 to 1 × 10−4 M choline with a correlation coefficient of 0.9999 and a detection limit of 0.2 μM, and had a high sensitivity of 61.9 mA·M−1·cm−2 at 0.50 V and at pH 8.0. The apparent Michaelis constant and the optimum pH for the immobilized enzyme are 1.4 mM choline
and 8.4, respectively, which are very close to those of choline oxidase in solution. The effect of selected organic compounds
on the response of the choline biosensor was studied. 相似文献