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881.
Two solid phase transitions of [Cd(H2O)6](BF4)2 occurring on heating at TC2=183.3 K and TC1=325.3 K, with 2 K and 5 K hysteresis, respectively, were detected by differential scanning calorimetry (DSC). High value of entropy changes indicated large orientational disorder of the high temperature and intermediate phase. Nuclear magnetic resonance (1H NMR and 19F NMR) relaxation measurements revealed that the phase transitions at TC1 and TC2 were associated with a drastic and small change, respectively, of the both spin-lattice relaxation times: T1(1H) and T1(19F). These relaxation processes were connected with the “tumbling” motions of the [Cd(H2O)6]2+, reorientational motions of the H2O ligands, and with the iso- and anisotropic reorientation of the BF4− anions. The cross-relaxation effect was observed in phase III. The line width and the second moment of the 1H and 19F NMR line measurements revealed that the H2O reorientate in all three phases of the title compound. On heating the onset of the reorientation of 3 H2O in the [Cd(H2O)6]+2, around the three-fold symmetry axis of these octahedron, causes the isotropic reorientation of the whole cation. The BF4− reorientate isotropically in the phases I and II, but in the phase III they perform slow reorientation only about three- or two-fold axes. A small distortion in the structure of BF4− as well as of [Cd(H2O)6]2+ is postulated. The temperature dependence of the bandwidth of the O-H stretching mode measured by Fourier transform middle infrared spectroscopy (FT-MIR) indicated that the activation energy for the reorientation of the H2O did not change much at the TC2 phase transition. 相似文献
882.
Development of a competitive ELISA for the quantification of F5 conjugate in HER2-targeted STEALTH immunoliposome doxorubicin in plasma samples 总被引:1,自引:0,他引:1
HER2 (human epidermal growth factor receptor 2, erbB2, or neu) is overexpressed by a large number of tumor types and has been
identified as an important target for cancer therapy. F5 is a single-chain human antibody fragment that recognizes HER2 receptor
and is covalently conjugated to PEGylated lipid to form F5 conjugate (F5CG) in the product HER2 targeted STEALTH immunoliposome
doxorubicin. Here we described the method development of a competitive enzyme-linked immunosorbent assay (ELISA) for the determination
of total concentration of F5 conjugate in plasma samples. The method involved the biotinylation of F5CG, detergent treatment
of plasma sample to solubilize F5CG into monomeric form, and competitive ELISA for solubilized F5CG competitively binding
to anti-F5CG antibody with biotinylated F5CG for the determination of total F5CG in plasma. The detection range of this method
was from 0.2 ng/mL to 125 ng/mL for F5CG in plasma. The lower limit of quantification (LLOQ) was 0.2 ng/mL. This method was
established and used for the measurement of F5CG concentration to provide information about F5CG circulation after the administration
of immunoliposome in preclinical studies.
相似文献
883.
884.
利用激光闪光光解-瞬态吸收光谱技术研究了355 nm 光作用下六氟苯(C6F6)-HNO2水溶液的反应机理, 探讨了中间产物及其动力学行为, 并对终产物进行了分析. 实验表明, C6F6可与HNO2光解产生的OH自由基反应生成加合物C6F6…OH, 二级反应速率常数为1.8×109 L·mol -1·s-1, 加合物吸收峰位置在250、270和400 nm处; C6F6…OH 加合物通过消除反应生成C6F5O·, 其表观生成常数为6.1×105 s-1. C6F6…OH与O2复合转化为C6F6OHO2, 二级反应速率常数为2.8×106 L·mol-1·s-1, C6F6OHO2峰位置与C6F6…OH 加合物相似. 终产物分析表明, OH自由基与六氟苯发生消除HF的反应而生成C6F5OH, 有O2时, 还产生四氟醌C6F4O2, 但无论有氧还是无氧体系, 均不发生硝基化反应. 相似文献
885.
Catherine Bessada Aydar Rakhmatullin Anne-Laure Rollet Didier Zanghi 《Journal of fluorine chemistry》2009,130(1):45-52
In situ high temperature nuclear magnetic resonance in molten fluoride mixtures gives some structural picture of the complexes existing in the melt, i.e. of their nature and relative proportion. Thanks to the development of a laser heating system associated with a close crucible in boron nitride, we can describe experimentally the evolution of these complexes from the anions and the cations point of view. By 19F NMR, we have shown the existence of three kinds of fluorine atoms depending on the composition: free fluorine like in pure LiF (non-bonded), bridging fluorine in melts rich in LnF3 in addition with terminal fluorine singly bonded to one rare earth. Data obtained by NMR spectroscopy are also combined with EXAFS measurements, again thanks to a specific development of the sample holder adapted with molten fluorides and high temperature. This study is a part of our systematic investigation of the different Alk-LnF3 systems by NMR and EXAFS spectroscopy. 相似文献
886.
Xing-an Wang ;Li Che ;Ze-feng Ren ;Ming-hui Qiu ;Dong-xu Dai ;Xiu-yan Wang ;Xue-ming Yang 《化学物理学报(中文版)》2009,22(6):551-555
Crossed beams scattering study was carried out on the F+HD→DF+H reaction using high- resolution H-atom Rydberg tagging time-of-flight technique. Vibrational state-resolved differential cross sections were measured, with partial rotational state resolution, at eight collision energies in the range of 2.51-5.60 kJ/mol. Experimental results indicated that the product angular distributions are predominantly backward scattered. As the collision energy increases, the backward scattered peak becomes broader gradually. Dependence of product vibration branching ratios on the collision energy was also determined. The experimental results show that the DF products are highly inverted in the vibrational state distribution and the DF (v'=3) product is the most populated state. Furthermore, the DF (v'=l) product has also been observed at collision energy above 3.97 kJ/mol. 相似文献
887.
Sharma PK Reilly MJ Bhatia SK Sakhitab N Archambault JD Bhatia SR 《Colloids and surfaces. B, Biointerfaces》2008,64(2):229-235
Pluronic F127, a triblock copolymer of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), has generated considerable interest as a drug delivery vehicle due to its ability to gel at physiological temperatures. This work examines the gelation behavior of Pluronic F127 in the presence of a series of hydrophobic pharmaceuticals, to determine whether there is any correlation between gelation and physicochemical parameters of drug solutes. The study includes the local anesthetics dibucaine, lidocaine, and tetracaine; the pharmaceutical additives methyl paraben, ethyl paraben, and propyl paraben; the anti-cancer agents paclitaxel and baccatin III; and the anti-inflammatory agent sulindac. The results indicate that the presence of local anesthetics and pharmaceutical additives allows F127 solutions to form gels at lower copolymer concentrations; local anesthetics and pharmaceutical additives also shift gelation down to a lower gelation temperature. This behavior is strongly dependent on drug solubility; poorly soluble drugs (paclitaxel, baccatin III, sulindac) do not change the lower gelation temperature or minimum F127 concentration for gelation. An equation relating the decrease in gelation temperature to drug solubility is presented, and the equation fits the data well. The results have significant positive implications on the toxicity and economic issues related to use of Pluronic F127 in drug delivery. 相似文献
888.
利用密度泛函理论研究了CH3CCl2F与F原子的反应机理.在MPW1K水平下计算了反应物、过渡态和产物的几何构型和频率,并进一步利用内禀反应坐标理论获得了反应的最小能量路径;在G3(MP2)水平下对所有驻点进行了单点能量校正.结果表明,CH3CCl2F与F原子的反应存在两个H迁移反应通道:CH2H′CCl 2F+F→C... 相似文献
889.
Na2MnPO4F材料是一种很有发展前景的钠离子电池正极材料,本文通过非原位XRD和固体核磁共振技术研究该材料充放电结构变化(晶体结构与局域Na位). 非原位XRD测试发现,充电过程在2θ为31o和36o左右出现新的衍射峰,表明钠脱出后电极上有中间相物质生成. 23Na MAS NMR谱图的-209 ppm、-258 ppm和-295 ppm三个谱峰分别对应于该材料结构中Na1 + Na2位、Na3位和Na4位. 非原位23Na MAS NMR谱研究发现,充电过程中-209 ppm处信号峰面积比例减小,表明Na1和Na2位的Na比Na3和Na4位先脱出. 充电至4.2 V,-132 ppm和-330 ppm处出现中间相物质的信号峰;而放电过程则相反. 相似文献
890.
嫁接Al改性MCM-41介孔分子筛催化合成双酚F 总被引:1,自引:0,他引:1
以十六烷基三甲基溴化铵和正硅酸乙酯为原料,合成纯硅MCM-41介孔分子筛。 再利用九水硝酸铝为改性剂来嫁接改性纯硅MCM-41介孔分子筛,NH3-TPD结果表明,嫁接后的AlMCM-41产生了中强酸。 用改性后不同n(Si)/n(Al)的AlMCM-41催化合成双酚F,在n(苯酚)/n(甲醛)=30、反应时间5 h、反应温度90 ℃、m(甲醛)/m(AlMCM-41)=7的反应条件下,在一定范围内,双酚F的产率随Al含量增加而增加,但在n(Si)/n(Al)<50时,双酚F的产率反而下降,当n(Si)/n(Al)=50时,双酚F的产率最高,为42.28%。 相似文献