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961.
A novel magnetic solid-phase extraction (MSPE) sorbent, magnetite/silica/poly (methacrylic acid–co-ethylene glycol dimethacrylate) (Fe3O4/SiO2/P(MAA-co-EGDMA)), was developed. This MSPE material was prepared by distillation–precipitation polymerization of MAA and EGDMA in the presence of Fe3O4/SiO2 microspheres with the surface containing abundant reactive double bonds. The resultant sorbent material was characterized by elemental analysis, electron microscopy, X-ray diffraction and Fourier-transformed infrared spectroscopy. In this work, eleven sulfonamides (SAs) were selected as model analytes to validate the extraction performance of this new MSPE sorbent. Noticeably, the extraction can be carried out quickly, the extraction time for the SAs onto Fe3O4/SiO2/P(MAA-co-EGDMA) sorbent can be clearly shortened to 0.5 min. The desorption solution of SAs was analyzed by LC–MS/MS, and the results showed that the recoveries of these compounds were in the range of 87.6–115.6%, with relative standard deviations ranging between 0.9% and 10.8%; the limit of detection were in the range of 0.5–49.5 ng/L. 相似文献
962.
The solubility and the critical relative humidity (H(cr)) of 14 drugs and inorganic salts were determined, the relationship between the H(cr) and the solubility was explored theoretically, and the H(cr) was calculated in the light of Raoult's law and Pitzer ion interaction model from their solubility. The results indicate that the H(cr) values calculated by Raoult's law in high humidity (H(cr)>80%) and by Pitzer ion interaction model in low humidity (H(cr)<80%) are comparable to the measured ones. 相似文献
963.
Zhang X Jiang X Zhang K Mao L Luo J Chi C Chan HS Wu J 《The Journal of organic chemistry》2010,75(23):8069-8077
A facile route has been developed for the preparation of a new family of contorted 1.2,3.4,7.8,9.10-tetrabenzocoronenes (TBCs). A two-step cyclization reaction, i.e., oxidative photocyclization followed by FeCl(3)-mediated intramolecular cyclodehydrogenation, was carried out on the olefin precursors to obtain the final TBC compounds. These new TBC molecules have contorted conformation due to steric overcrowding as disclosed by single-crystal crystallographic analysis. Nevertheless, they showed extended π-conjugation compared with coronene and exhibited strong aggregation in solution. The thermal behavior and self-assembly of TBC-C8 in solid were studied by a combination of thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM). Compound TBC-C8 showed very good thermal and photostability and exhibited long-range ordered π-stacking in the bulk state. Moreover, uniform nanofibers with tens of micrometer length are formed in the drop-casted thin films. TBC-C8 also possesses a desirable HOMO energy level (-5.10 eV), which allows efficient charge injection from electrodes such as gold electrode. The charge carrier mobilities were determined by using the space-charge limited-current (SCLC) technique and high average hole mobility of 0.61 cm(2) V(-1) s(-1) was obtained for TBC-C8. 相似文献
964.
A novel method using liquid chromatography coupled to electrospray ionization mass spectrometry (LC-ESI-MS) has been optimized and established for the qualitative and quantitative analysis of ten active phenolic compounds originating from the pigeon pea leaves and a medicinal product thereof (Tongluo Shenggu capsules). In the present study, the chromatographic separation was achieved by means of a HiQ Sil C18V reversed-phase column with a mobile phase consisting of methanol and 0.1% formic acid aqueous solution. Low-energy collision-induced dissociation tandem mass spectrometry (CID-MS/MS) using the selected reaction monitoring (SRM) analysis was employed for the detection of ten analytes which included six flavonoids, two isoflavonoids and two stilbenes. All calibration curves showed excellent coefficients of determination (r(2) ≥ 0.9937) within the range of tested concentrations. The intra- and inter-day variations were below 5.36% in terms of relative standard deviation (RSD). The recoveries were 95.08-104.98% with RSDs of 2.06-4.26% for spiked samples of pigeon pea leaves. The method developed was a rapid, efficient and accurate LC-MS/MS method for the detection of phenolic compounds, which can be applied for quality control of pigeon pea leaves and related medicinal products. 相似文献
965.
将水合碳酸铈与硝酸铝和氨水共同进行机械球磨,使新形成的无定型氢氧化铝包覆在细小的碳酸铈颗粒表面,经脱水干燥和煅烧,以制备出表面掺杂有氧化铝的氧化铈。结果表明:球磨中间产物仍然以水合碳酸铈为主,氢氧化铝的形成阻碍了碳酸铈的无定型化和向氢氧化铈的转化过程。在氧化铝掺杂量不超过10%的条件下,煅烧产物均具有立方萤石型结构。所有掺杂铝的氧化铈粉体对ZF7和K9光学玻璃的抛光速率均比纯氧化铈的有很大提高,证明铝的掺杂能够大大提高氧化铈的抛光性能。其最佳掺杂量为0.6%,煅烧条件为在1000℃下煅烧2 h。此时的MRR值为纯氧化铈的两倍以上。 相似文献
966.
NdFeB材料微波吸收特性的研究 总被引:3,自引:0,他引:3
采用高能球磨和晶化热处理方法制备钕铁硼吸波粉体,研究制备工艺对钕铁硼粉体吸波性能的影响。结果发现:高能球磨和适当晶化热处理可改善NdFeB粉体的组织结构、复介电常数和复磁导率;NdFeB粉体的反射率最小值为-15.5 dB,高能球磨48 h后粉体的反射率最小值降到-23 dB,高能球磨粉体经600℃晶化热处理后反射率最小值为-19 dB;高能球磨和晶化热处理可降低NdFeB粉体的吸收峰频率;高能球磨会使NdFeB粉体的吸波带宽变窄,经600℃晶化热处理后吸波带宽变宽,并且随着晶化热处理的温度升高,吸波带宽变得更宽。 相似文献
967.
微流控芯片在表面等离子体共振生物传感器中的应用 总被引:1,自引:0,他引:1
作为众所周知的生物传感器技术,表面等离子体共振(SurfacePlasmonResonance,SPR)正在被越来越普遍地用于实现各种生物化学检测方法,特别是用途广泛的固相表面生物检测(Sol—id—PhaseBioassay)。SPR对样品进行非标记检测,能够用于测量生物化学反应全过程的反应动力学。为了提高SPR的检测效率,通常将微流控技术(Microfluidics)与SPR相结合,即在SPR生物传感器中使用微流控芯片(MicrofluidicChip)作为反应装置。基于微型化带来的优势,使用微流控芯片作为反应装置可以有效地缩短生物化学检测方法的反应时间,并减少样品消耗。微流控芯片还可以平行排布相同的结构单元,提高SPR生物传感器的检测通量。因此,使用微流控芯片作为反应装置是SPR生物传感器,特别是商品化的SPR生物传感器的发展趋势。 相似文献
968.
In this paper, an active backstepping design is proposed to achieve combination synchronization between three different chaotic systems: Lorenz system, Chen's system, and Lu? system. The proposed method is a systematic design approach and consists in a recursive procedure that interlaces the choice of a Lyapunov function with the design of active control. Numerical simulations are shown to verify the feasibility and effectiveness of the proposed control technique. 相似文献
969.
In the present study, a GPU accelerated 1D space–time CESE method is developed and applied to shock tube problems with and without condensation. We have demonstrated how to implement the CESE algorithm to solve 1D shock tube problems using an older generation GPU (the NVIDIA 9800 GT) with relatively limited memory. To optimize the code performance, we used Shared Memory and solved the inter-Block boundary problem in two ways, namely the branch scheme and the overlapping scheme. The implementations of these schemes are discussed in detail and their performances are compared for the Sod shock tube problems. For the Sod problem without condensation, the speedup over an Intel CPU E7300 is 23 for the branch scheme and 41 for the overlapping scheme, respectively. While for problems with condensation, both schemes achieve higher acceleration ratios, 53 and 71, respectively. The higher speedup of the condensation case can be ascribed to the source term calculation which has a local dependence on the mesh point and the SOURCE kernel has a higher acceleration ratio. 相似文献
970.
Novel limiters based on the weighted average procedure are developed for finite volume methods solving multi-dimensional hyperbolic conservation laws on unstructured grids. The development of these limiters is inspired by the biased averaging procedure of Choi and Liu [10]. The remarkable features of the present limiters are the new biased functions and the weighted average procedure, which enable the present limiter to capture strong shock waves and achieve excellent convergence for steady state computations. The mechanism of the developed limiters for eliminating spurious oscillations in the vicinity of discontinuities is revealed by studying the asymptotic behavior of the limiters. Numerical experiments for a variety of test cases are presented to demonstrate the superior performance of the proposed limiters. 相似文献