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71.
以硝酸铽、苯乙酮酸(HL), 2, 2'-联吡啶(dipy)、 1, 10-菲啰啉(phen)和三苯基氧膦(TPPO)合成了TbL3dipy(H2O)2, TbL3phen(H2O)2和TbL2(TPPO)2NO3 3种新型固态配合物. 用元素分析、电导率、红外光谱和核磁共振谱对其进行了表征, 确定了配合物的组成. IR表明, 配合物中羧酸根可能以单齿方式配位. 1HNMR显示, 苯乙酮酸根配位后苯环上5个氢原子的化学位移移向高场. 室温下测定了配合物的荧光激发光谱, TbL3dipy(H2O)2, TbL3phen(H2O)2和TbL2(TPPO)2NO3最佳激发波长分别为361.0, 359.0和367.0 nm;分别以最佳激发波长测定了配合物的发射光谱, 配合物TbL3dipy(H2O)2, TbL3phen(H2O)2 和TbL2(TPPO)2NO3显示Tb3+离子的特征发射光谱, TbL3dipy(H2O)2和TbL3phen(H2O)2均产生四条谱带, 分别归属于^5D4-^7Fj(j= 6, 5,4,3)能级跃迁(TbL3dipy(H2O)2: 489.0, 545.0, 584.0, 620.0 nm;TbL3phen(H2O)2: 490.0, 544.0, 583.0, 620.0 nm);但在相同测定条件下, TbL2(TPPO)2NO3仅显示5D4-7F5(544.0 nm)能级跃迁光谱. 3种配合物中TbL3dipy(H2O)2发光强度最高. 相似文献
72.
Isolation and purification of honokiol and magnolol from cortex Magnoliae officinalis by high-speed counter-current chromatography 总被引:5,自引:0,他引:5
High-speed counter-current chromatography was used to isolate and purify honokiol and magnolol from cortex Magnoliae Officinalis (Magnolia officinalis Rehd. et Wils.), a plant used in the traditional Chinese medicine. A crude sample, 150 mg, was successfully separated with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (1:0.4:1:0.4, v/v), and the fractions were analyzed by high-performance liquid chromatography. The separation produced 80 and 45 mg of honokiol and magnolol with purities of 99.2 and 98.2%, respectively, in 2.5 h. 相似文献
73.
SynthesisandMagnetismof2┐Hydroxy┐1,3┐propylene┐bis(oxamato)┐bridgedCoⅡCuⅡCoⅡComplexesMIAOMing-ming,CHENGPeng,LIAODai-zhengJIA... 相似文献
74.
偶合反应化学发光法测定痕量银的研究 总被引:6,自引:0,他引:6
本将Ag(Ⅰ)催化S2O^2-8氧化Mn(Ⅱ)生成MnO^-4的催化反应与LuminolMnO^-4-OH^-的化学发光反应相偶合,建立起一种新的灵敏测定痕量银的化学发光分析法,在所研究的优化条件下,该法测定银的选择性较好,检测限达到3.2×10^-12g/mLAg线性浓度范围为1.0×10^-11-1.0×10^-5g/mLAg,用于水样分析,结果较为满意。 相似文献
75.
Ji-Lai Li Cai-Yun Geng Xu-Ri Huang Chia-Chung Sun 《Theoretical chemistry accounts》2007,117(3):417-429
The reaction of atomic radical F with propyne has been studied theoretically using ab initio quantum chemistry methods and
transition state theory. The potential energy surface was calculated at the CCSD(T)/aug-cc-pVDZ (single-point) level using
the UMP2/6-311++G(d,p) optimized structures. Two reaction mechanisms including the addition–isomerization–elimination reaction
mechanism and the directed hydrogen abstraction reaction mechanism are considered. For the hydrogen abstraction reactions,
i.e., the most probable evolution pathway in the title reaction, the HF formation occurs via direct abstraction mechanism
dominantly and the H atom picked up by the atomic radical F should come mostly from the methyl group of normal propyne. On
the other hand, for the addition–isomerization–elimination mechanism, the most feasible pathway should be the atomic radical
F attacking on the C≡C triple bond in propyne (CH3C≡CH) to form a weakly-bound adduct A1 with no barrier, followed by F addition to the C≡C triple bond to form the low-lying
intermediate isomer 5. Subsequently, isomer 5 directly dissociates to P3 H2CCCHF + H via transition state TS5/P3. The other reaction pathways on the doublet PES are less competitive due to thermodynamical or kinetic factors. Furthermore,
based on the analysis of the kinetics of all channels through which the addition and abstraction reaction proceed, we expect
that the competitive power of reaction channels may vary with experimental conditions for the title reaction. The present
work will provide useful information for understanding the processes of atomic radical F reaction with other unsaturated hydrocarbons.
This material is available from author via E-mail. 相似文献
76.
Paulus UA Wang Y Kim SH Geng P Wintterlin J Jacobi K Ertl G 《The Journal of chemical physics》2004,121(22):11301-11308
Catalytic CO oxidation on the RuO(2)(110) surface was studied at 300 K by scanning tunneling microscopy (STM), high-resolution electron-energy-loss spectroscopy (HREELS), and thermal desorption spectroscopy (TDS). Upon repeatedly exposing the surface to several 10 L of CO and O(2) at 300 K, STM shows that unreactive features accumulate with each CO and O(2) titration run. HREELS and TDS show formation of increasing amounts of H(2)O, retarded formation of O-cus atoms and incomplete removal of CO-bridge molecules during O(2) dosing, and a changing ratio of single- and double-bonded CO-bridge molecules. It is concluded that H(2)O (presumably from the residual gas) is accumulating at the Ru-cus sites thus blocking them, so that the dissociative adsorption of oxygen is prevented and the CO oxidation reaction is suppressed. Some 10% CO- bridge remains on the surface even during oxygen exposure. Consistent with this interpretation, deactivation of the surface is suppressed at 350 K, at the onset of H(2)O desorption. 相似文献
77.
Hongyang Su Lanlan Chen Yizhen Chen Prof. Rui Si Yuting Wu Xiaonan Wu Dr. Zhigang Geng Prof. Wenhua Zhang Prof. Jie Zeng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(46):20591-20596
Efforts have been devoted to achieving a highly efficient artificial synthesis of ammonia (NH3). Reported herein is a novel Fe-MoS2 catalyst with Fe atomically dispersed onto MoS2 nanosheets, imitating natural nitrogenase, to boost N2 electroreduction into NH3 at room temperature. The Fe-MoS2 nanosheets exhibited a faradic efficiency of 18.8 % with a yield rate of 8.63 μg mgcat.−1 h−1 for NH3 at −0.3 V versus the reversible hydrogen electrode. The mechanism study revealed that the electroreduction of N2 was promoted and the competing hydrogen evolution reaction was suppressed by decorating the edge sites of S in MoS2 with the atomically dispersed Fe, resulting in high catalytic performance for the electroreduction of N2 into NH3. This work provides new ideas for the design of catalysts for N2 electroreduction and strengthens the understanding about N2 activation over Mo-based catalysts. 相似文献
78.
The crystallization processes of hydrated Mg-borates, boric, magnesium hydroxide and Mg-oxychloride from MgO-B2O3-18%MgCl2-H2O supersaturated solution at 20°C have been studied by kinetic method. The crystallization solid phases were characterized
by X-ray powder diffraction, IR spectra, thermal analysis and chemical analysis. The liquid-solid phase diagram of thermodynamic
nonequilibrium state has been given. In this phase diagram, there exist eight crystallization fields, boric acid(H3BO3), trigomagneborite(MgO · 3B2O3 · 7.5H2O, MgO · 3B2O3 · 7H2O), hungchaoite(MgO · 2B2O3 · 9H2O), inderite(2MgO · 3B2O3 · 15H2O), chloropinnoite(2MgO · 2B2O3 · MgCl2 · 14H2O), magnesium hydroxide(Mg(OH)2) and magnesium oxychloride (5Mg(OH)2 · MgCl2 · 8H2O). 相似文献
79.
The rheological behavior and the morphology in blends of polyethylene terephthalate (PET) with ionomeric polyester were investigated over a wide range of different blending ratios. The ionomeric polyester is derived from PET modified through copolycondensation with sulfonate moiety, sodiosulfo isophthalate (Na-SIP), iso-phthalic acid (IPA) and polyethylene glycol (PEG). The results showed that the apparent viscosity and non-Newtonian index of the PET/ionomeric polyester blend system had a nonlinearity change with the change of the blend ratio of PET/ionomeric polyester. The anomaly of the viscous flow activation energy change was found as the content of ionomeric polyester was about 40% (w/w) in the blend system, suggesting the presence of physical cross-linked structure formed by strong polar tangling points and the phase separation owing to poor compatibility between the PET and ionomeric polyester. The morphology and thermal behavior of the blends were observed, respectively, with differential scanning calorimetry (DSC) and atomic force microscopy (AMF). 相似文献
80.
Ru‐Jong Jeng Geng‐Sheng Lo Chih‐Ping Chen Ying‐Ling Liu Ging‐Ho Hsiue Wen‐Chiung Su 《先进技术聚合物》2003,14(2):147-156
Epoxy resins modified by an organosoluble phosphorus‐containing bismaleimide (3,3′‐bis(maleimidophenyl) phenylphosphine oxide; BMPPPO) were prepared by simultaneously curing epoxy/diaminodiphenylmethane (DDM), and BMPPPO. The resulted epoxy resins were found to exhibit glass transition temperatures as high as 212 °C, thermal stability at temperatures over 350 °C, and excellent flame retardancy with Limited oxygen index (LOI) values around 40. Incorporation of BMPPPO into epoxy resins via the thermosetting blend was demonstrated to be an effective way to enhance the thermal properties and flame retardancy simultaneously. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献