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931.
The use of a laboratory-made iodide ion-selective electrode with tubular configuration and based on a crystalline membrane (AgI/Ag2S) as the detector for ion chromatographic determination of iodide in urine and serum is described. A CIS reversed-phase column was coated withN-cetylpyridinium chloride to prepare a low-exchange-capacity analytical column and with hexadecyltrimethylammonium bromide to prepare a concentrator pre-column. A 2.0 ml min–1 flow rate of deionized water and 0.1 mol 1–1 KNO3 solution was used for the pre-concentration and for the chromatographic separation, respectively. For optimum performance of the detector a background level of iodide was added into the column effluent. A linear relationship (r = 0.9997) between tubular electrode potential (as peak height) and iodide concentration in the range 5–400 g 1–1 and a detection limit of 1.47 g 1–1 were obtained. The method shows good reproducibility for both peak height (2.2% RSD) and retention time (1.3% RSD). Recoveries on its application to the samples were 93.0–100.9% for urine and 91.4–106.0% for serum. 相似文献
932.
Jia-Heng Lei Dan Liu Li-Ping Guo Xue-Min Yan Hui Tong 《Journal of Sol-Gel Science and Technology》2006,39(2):169-174
Large-sized, optical transparent mesostructured Brij 56/silica monolith has been fabricated using a lyotropic liquid crystal
of Brij 56 (C16EO10) as a template and TMOS as a silica source, combined with a optimizing sol-gel process and a hydrothermal aging process.
By programmed temperature drying and calcinations, translucent mesoporous silica monolith with two-dimensional hexagonal structure
(P6mm) has bee obtained. The ordered mesoporous silica monoliths have been characterized by small-angle X-ray diffraction, transmission
electron microscopy (TEM), and nitrogen adsorption, which shows that the materials have a highly ordered two-dimensional hexagonal
mesostructure with the high specific surface area of 837 m2 · g−1 and narrow pore distribution with a mean BJH pore diameter of 2.73 nm. Based on calculations and differential scanning calorimetry
and thermogravimetric analyses, the action mechanism of the hydrothermal aging process has been proposed: the 100°C hydrothermal
conditions and autogenous 2.3 atm pressure promote the condensation and dehydration of silanol groups, with the result that
cross-linking degree, the flaws and moisture content in gels are reduced notably. Those processes guarantee the integrity
of gels in the following drying process. 相似文献
933.
Joseph A. Rard Kirk J. Staggs S. Dan Day Susan A. Carroll 《Journal of solution chemistry》2006,35(8):1187-1215
Boiling temperature measurements have been made at ambient pressure for saturated ternary solutions of NaCl + KNO3 + H2O, NaNO3 + KNO3 + H2O, and NaCl + Ca(NO3)2 + H2O over the full composition range, along with those of the single salt systems. Boiling temperatures were also measured for the four component NaCl + NaNO3 + KNO3 + H2O and five component NaCl + NaNO3 + KNO3 + Ca(NO3)2 + H2O mixtures, where the solute mole fraction of Ca(NO3)2, x{Ca(NO3)2}, was varied between 0 and 0.25. The maximum boiling temperature found for the NaCl + KNO3 + H2O system is ≈134.9 ∘C; for the NaNO3 + KNO3 + H2O system is ≈165.1 ∘C at x(NaNO3) ≈ 0.46 and x(KNO3) ≈ 0.54; and for the NaCl + Ca(NO3)2 + H2O system is 164.7 ± 0.6 ∘C at x{NaCl} ≈ 0.25 and x{Ca(NO3)2} ≈ 0.75. The NaCl + NaNO3 + KNO3 + Ca(NO3)2 + H2O system forms molten salts below their maximum boiling temperatures and the temperatures corresponding to the cessation of boiling (dry-out temperatures) of these liquid mixtures were determined. These dry-out temperatures range from ≈300 ∘C when x{Ca(NO3)2} = 0 to ≥ 400 ∘C when x{Ca(NO3)2} = 0.20 and 0.25. Mutual deliquescence/efflorescence relative humidity (MDRH/MERH) measurements were also made for the NaNO3 + KNO3 and NaCl + NaNO3 + KNO3 salt mixture from 120 to 180 ∘C at ambient pressure. The NaNO3 + KNO3 salt mixture has a MDRH of 26.4% at 120 ∘C and 20.0% at 150 ∘C. This salt mixture also absorbs water at 180 ∘C, which is higher than expected from the boiling temperature experiments. The NaCl + NaNO3 + KNO3 salt mixture was found to have a MDRH of 25.9% at 120 ∘C and 10.5% at 180 ∘C. The investigated mixture compositions correspond to some of the major mineral assemblages that are predicted to control brine composition due to the deliquescence of salts formed in dust deposited on waste canisters in the proposed nuclear repository at Yucca Mountain, Nevada. 相似文献
934.
ClnOPodiumpoIycePhalum(VantjCYWhetHsuancalled'DuanXielin'inChineseisusedinfolkmedicineforthetreatInentofhaemorrhagiadisease.lInordertofmdtheactivecomPounds,studiesonthechedricalconstituentsofthewholeplan,collectedatHuoShanofAnhuiprovince,werecarriedout.Fromthealcoholicextracts,wehaveisolatedanewanthraquinone,Glyceroyl-l,6,8-trihydroxy-3-methyl-9)lO-dioxo-2-anthrcenecarboxylateI(Figurel).Iwasobtainedasredneedles,mP:ll9-l2l"C.TheHR-MSdareaffordedthefor-mulaasCl9Hl6O9(Found388.O791;… 相似文献
935.
Li Qiu WANG Xiao Jun PENG* Rong ZHANG Guo Quan XU Jing Nan CUI State Key Laboratory of Fine Chemicals Dalian University of Technology Dalian 《中国化学快报》2003,(1)
Indocyanine dyes as fluorescent labeling reagents have been used in bioanalysis1,2. Arylsulfonate indocyanine dyes 1d and 1e developed by Waggoner A. S. et al.3,4 have excellent fluorescent properties combined with good aqueous solubility, are a new generation of fluorescent label compounds for proteins, oligonucleotides and other compounds containing hydroxyl, mercaptol or primary amine groups5. However, photostability of these dyes has been a problem. Z. G. YAO et al.6 reported that p… 相似文献
936.
Background Pillar[n]arene(PA[n])contains a symmetrical structures,where para-bridge connection between the units looks like a column-like or pillar shape and polygonal structure from side and top views,respectively.The attached groups to the PA[n]are pointing towards the opposite directions along the columnar axis. 相似文献
937.
以cis-1,2-二氰基乙烯-1,2-二硫醇钠(Na2(mnt))、2,2′-联吡啶-1,1′-二氧化物(bipyO2)和NiCl2为原料,合成了一种具有大共轭体系的混配型配合物.用元素分析、差热 热重分析、摩尔电导、红外和紫外光谱对配合物进行表征.该配合物化学式为Ni(mnt)(bipyO2),平面正方形结构,属电中性物质,热分解温度高于335 ℃.不溶于水和常规有机溶剂,可溶于DMSO.该配合物是一种氨敏材料,用它制作的传感器对氨气具有良好的敏感性和选择性;当工作电压为10 V时,在氨气浓度小于2.6 mmol•L-1的范围,传感器的输出信号对氨气呈线性响应.传感器的平均回收率为100.2%,响应时间为20 s,恢复时间为45 s.可用于微量氨的定量分析. 相似文献
938.
Jun Wang Michael G. Gardiner Brian W. Skelton 《Journal of organometallic chemistry》2005,690(1):220-227
The synthesis of 2,5-bis{(diethyl-3′-indolyl)methyl}furan by the acid catalysed condensation of 2,5-bis(diethylhydroxymethyl)furan with indole is presented. Dilithium, disodium and dipotassium derivatives are prepared by the reaction of the bis(indole) with n-BuLi, NaH and K, respectively, in the presence of various Lewis bases. The X-ray structures of 2,5-bis{(diethyl-3′-indolyl)methyl}furan and the dilithiated derivative (as a polymeric tetrahydrofuran adduct) are reported. 相似文献
939.
Determination of amino acids in a complex matrix without derivatization is advantageous, however, difficulties are found in both the detection and the separation of those compounds. In this study, a rapid and reliable LC-MS-MS method for the quantitation of underivatized amino acids in exocellular media was established. Injections were made directly after centrifugation of the samples, without further preparation. The separation of seven underivatized amino acids was achieved on a reversed-phase C18 column with pentadecafluorooctanoic acid as a volatile ion-pair reagent, and the specific detection of most amino acids was achieved by MS-MS of the specific transitions [M + H]+-->[M + H - 46]+. The calibration curves of all analytes were linear over the range of 1.0-1000 microg ml(-1) and the detection limits ranged from 0.1 to 5 ng ml(-1), with an injection volume of 20 microl. The inter-day and intra-day precisions ranged from 2.6 to 5.7% and 4.8 to 8.2%, respectively; the mean recoveries of the seven analytes were 81-104%, 91-107% and 93-101% respectively at the spiked level of 10, 40 and 200 microg ml(-1). A large number of fermentation samples were analysed using this method. The technique is simple, rapid, selective and sensitive, and shows potential for the high-throughput quantitation of amino acids from other biological matrices. 相似文献
940.
YingXinLIU ZuoJunWEI JiXiangCHEN JiYanZHANG XinXueLI XiongHuiWEI 《中国化学快报》2005,16(4):531-533
A novel lanthana-promoted nickel catalyst supported on silica for the liquid phase hydrogenation of m-dinitrobenzene to m-phenylenediamine was prepared by an incipient wetness sequential impregnation method. It was found that Ni-La/SiO2 catalyst exhibited high activity and stability for m-dinitrobenzene hydrogenation. Over this catalyst, the conversion of m-dinitrobenzene and the yield of m-phenylenediamine were up to 97.1% and 93.5%, respectively,at 373 K and 2.6 MPa hydrogen pressure after reaction for 1 h. 相似文献