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971.
电解还原法是近年来国际上逐步使用的一种新的卤化银颗粒尺寸和分布测定的方法.用此方法,我们研制了我国第一台微机化的测量仪。这台仪器可以测量直径从0.1μm至40μm的所有各种卤化银颗粒,而且全部操作,包括信号的提取、识别、数字化转换以及数据处理都是自动进行。与过去常用的测量方法,如电镜图象分析法、离心沉降法以及激光散射法相比,此方法测量快速,测量精度高并且设备投资少,操作方便.此外,我们还对电解法与电镜法的测试结果作了比较。 相似文献
972.
Jieshan Qiu Hongzhe Zhang Xiuna Wang Hongmei Han Changhai Liang Can Li 《Reaction Kinetics and Catalysis Letters》2006,88(2):269-276
Summary Carbon nanotube supported Pd, Ru and Pd-Ru catalysts have been prepared and tested with the hydrogenation of cinnamaldehyde
as a probe reaction. It has been found that the cinnamaldehyde conversion and the selectivity towards the hydrogenation of
C=O bond over Pd-Ru/PCNT catalyst could reach 56.6% and 79.1%, respectively, at 120oC and 5.0 MPa, which is better than Pd/PCNT and Ru/PCNT catalysts under the same reaction conditions. It is assumed that the
better performance of Pd-Ru/PCNT catalyst for cinnamaldehyde hydrogenation may be due to the synergic effect of Pd and Ru
metals or the promoting effect of Ru metal. 相似文献
973.
SUN Chengke ZHAO Hongmei & LI Zonghe . Department of Chemistry Beijing Normal University Beijing China . Department of Chemistry Qujing Normal College Qujing China 《中国科学B辑(英文版)》2004,47(5):373-380
Since the first discovery of azoalkanes in 1909,the studies of the chemistry of azoalkane radicals havegone through a long history and many significativeresults have been gotten during the past 30 years[1,2].These versatile compounds lose nitrogen thermally orphotochemically under a wide variety of conditions:R─N═N─R ? 2R?+ N2; hence, they are probablythe cleanest and most convenient sources of variousradicals and biradicals of nearly any desired structure.Several reviews on the applicati… 相似文献
974.
Determination of carbendazim, thiabendazole and fuberidazole using a net analyte signal-based method
Martı́nez Galera M Picón Zamora D Martı́nez Vidal JL Garrido Frenich A Espinosa-Mansilla A Muñoz de la Peña A Salinas López F 《Talanta》2003,59(6):1107-1116
The net analyte signal (NAS)-based method HLA/GO, modification of the original hybrid linear analysis (HLA) method, has been used to determine carbendazim, fuberidazole and thiabendazole in water samples. This approach was used after a solid-phase extraction (SPE) step, using the native fluorescence emission spectra of real samples, previously standardized by piecewise direct standardization (PDS). The results obtained show that the modification of HLA performs in a similar way that partial least-squares method (PLS-1). The NAS concept was also used to calculate multivariate analytical figures of merit such as limit of detection, selectivity, sensitivity and analytical sensitivity (γ−1). With this purpose, blanks of methanol and ternary mixtures, with the target analyte at low concentration and the other two ranging according to the calibration matrix, were used, with different results. Detection limits calculated in the last way are more realistic and show the influence of the other components in the sample. Selectivity for carbendazim is higher than the corresponding values for fuberidazole and thiabendazole, whereas sensitivity, as well as the values obtained for their detection limits, are lower for carbendazim, followed by thiabendazole and fuberidazole. Results obtained by modification of HLA vary in the same way that the ones obtained by PLS-1. 相似文献
975.
将水面上漂浮的不溶性单分子膜转移到固体基片上,所得到的单分子或多分子层膜称为Langmuir-Blodgett膜,简称LB膜。它在微电子学、光学、磁学及生物和化学传感器等方面都具有广泛的应用前景。硬脂酸镉(CdSt_2是有代表性的成膜物质,人们常将它用作模型化合物来深入探讨其LB膜的周期结构与膜厚的关系,设立模型进行拟合,试图得到带 相似文献
976.
977.
Mahedero MC Díaz NM Muñoz de la Peña A Espinosa Mansilla A Gónzalez Gómez D Bohoyo Gil D 《Talanta》2005,65(3):806-813
A widely employed compound for honey treatment, sulfathiazole (ST), was determined in commercial honey samples, employing a combination of photochemically induced fluorescence excitation-emission matrices (EEMs) and chemometric processing of the recorded second-order data. Parallel Factor Analysis (PARAFAC) and Self-Weighted Alternating Trilinear Decomposition (SWATLD) methods were used for calibration. An appropriately designed calibration with a set of standards composed of 18 samples, coupled to the use of the second-order advantage offered by the applied chemometric techniques, allowed quantitation of sulfathiazole in spiked commercial honey samples. No previous separation or sample pretreatment steps were required. The results were compared with other calibration methods such as N-PLS and PLS-1 that produced good results on synthetic samples but not on the investigated commercial honey samples. 相似文献
978.
Peix A Rivas R Velázquez E Mateos PF Martínez-Molina E Muñoz-Herrera A Gómez-Alonso A Velázquez E 《Electrophoresis》2005,26(23):4402-4410
The random intergenic spacer analysis is a recently developed technique for the study of microbial populations. The bacterial intergenic spacer (ITS) is located between 16S rRNA and 23S rRNA genes and presents different length and sequence among bacterial species. Therefore, the amplicons can be separated by electrophoresis commonly performed at low voltage during several hours. Although this technique is especially useful for unculturable microorganisms, it has not been applied before to clinical sample analysis. As these samples have a limited number of bacterial species, the size of the gels may be reduced to facilitate their handling and to reduce the running time. To obtain maximum separation among the ITS bands, we analysed in this work different electrophoretical conditions including staircase electrophoresis, a technique based on the application of several voltage steps. The results obtained showed a different behaviour of the electrical resistance during the performance of submarine horizontal and vertical staircase electrophoresis. In the first case the resistance decreased during most of the running time whereas in the second case it increased. Here, we show that the performance of horizontal staircase electrophoresis reduces the running time more than 80% with respect to conventional electrophoresis at low voltages. This procedure was applied to the separation of ITS bands from bacterial DNA present in a tissue from a vocal cord biopsy. The sequencing of these bands allowed their identification. This new procedure may be very useful in the rapid diagnosis of bacteria present in human, animal and plant tissues. 相似文献
979.
Prieto M Zurita E Rosa E Muñoz L Lloyd-Williams P Giralt E 《The Journal of organic chemistry》2004,69(20):6812-6820
Yields of Suzuki couplings involving indoles depended upon (i) whether arylboronic acids or arylpinacolboronate esters were used, (ii) whether the heterocycle was the aryl halide or the arylboron coupling partner, and (iii) whether the heterocycle was protected or not. Highest yields, which were unaffected by incorporating Boc or Tos protection at the heterocyclic nitrogen, were obtained when indole bromides were reacted with phenylboronic acids. When indolylboronic acids were reacted with phenyl bromides, yields were somewhat lower and depended on the nitrogen substituent, being highest in the absence of protection, lower in the presence of the Boc group, and lowest of all with the Tos group. Arylpinacolboronate esters were less reactive than arylboronic acids. They required considerably longer reaction times and furnished generally lower yields of biaryl. Furthermore, irrespective of whether the heterocycle was the aryl bromide or the arylpinacolboronate ester, these yields were highest when it was protected with the Tos group. Yields were lower with the Boc group, and unprotected heterocycles gave only traces of biaryl. Careful selection of arylboron reagent, of coupling partner roles, and of protecting groups are essential to ensuring optimum results in these Suzuki couplings. These results may also be relevant to couplings involving other substrates. 相似文献
980.
新型免疫电极法测定乙型肝炎表面抗原 总被引:7,自引:0,他引:7
本文报道一种新型的乙型肝炎抗体膜片。测试时,仅需将25μl被检血清滴注于该膜上,经孵育与洗涤即可制得抗原与抗体复合物膜。用复合物膜组装成免疫电极,测定血清样品中乙型肝炎表面抗原含量。电极的线性范围是20~320ng/ml,方法的日间相对标准偏差为10.78%(n=4,m=5),对血清中可能存在的一些其它抗原具有较好的选择性。105例临床血清样本,本法与酶联免疫吸附分析法测定结果符合率为86%。乙肝抗体膜片系一次性使用,4℃可保存半年以上。 相似文献