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961.
962.
A new type of SiO_2-MgO-CaO (SMC) whisker was used to modify high density polyethylene (HDPE).The melting behavior and crystallinity were investigated by differential scanning calorimetry (DSC).The dispersion of whiskers and interfacial adhesion in the prepared HDPE/SMC whisker composites were investigated by scanning electron microscopy (SEM).The mechanical properties were evaluated by mechanical tests and dynamic mechanical analysis (DMA).DSC data indicated that the melting temperature and the crystall... 相似文献
963.
3α-Hydroxyl-7α-(4-pentenoyloxy)-5β-cholanoic acid (5) has been synthesized in four step reactions starting from CDCA. The serendipitous synthesis of methyl 3α-(ethoxycarbonyloxy)-7α-(allyloxycarbonyloxy)-5β-cholanoate (7) has led us to compare the spectroscopic difference of the 7α-(allyloxycarbonyloxy) group versus the 7α-(4-pentenoyloxy) group. The molecular structures of these compounds were confirmed by X-ray crystallography. Methyl 3α-(ethoxycarbonyloxy)-7α-(allyloxycarbonyloxy)-5β-cholanoate was obtained by a method, which may prove useful in the synthesis of 14C-labeled derivatives for metabolic studies. 相似文献
964.
Z. F. Yin Y. R. Feng W. Z. Zhao Z. Q. Bai G. F. Lin 《Surface and interface analysis : SIA》2009,41(6):517-523
This work investigates the effect of temperature on the corrosion product layer of carbon steel exposed to a CO2‐containing solution. The measurement techniques, such as scanning electron microscopy with energy dispersive spectrometry, X‐ray diffraction, and X‐ray photoelectron spectroscopy, were used to systematically characterize the morphology and composition of the corrosion product layer. The corrosion rates were calculated by weight loss method. The corrosion mechanisms as a function of temperature are studied and discussed. The results showed that temperature is an important factor in the corrosion rate of carbon steel. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
965.
以N,N’-二对甲苯磺酰基-4,4’-二氨基二苯砜与二溴代烷为原料, 高度稀释条件下合成了三种新型有硫原子桥连的氮杂环蕃N,N’-二对甲苯磺酰基-1,8-二氮杂[8.1]对环蕃-15-砜(C); N,N’-二对甲苯磺酰基-1,10-二氮杂[10.1]对环蕃-17-砜(D); N,N’-二对甲苯磺酰基-1,12-二氮杂[12.1]对环蕃-19-砜(E). 提供了三种环蕃化合物的合成方法. 用IR, 1H NMR和元素分析证实了新化合物结构. 分析了化合物D的单晶结构数据, 为环蕃化合物的空间结构研究提供了晶体学依据. 相似文献
966.
Mingwei Zhao Liqiang Zheng Xiangtao Bai Na Li Li Yu 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,346(1-3):229-236
Silica products with two different morphologies were synthesized using nonaqueous ionic liquid microemulsion droplets as templates. The morphologies of the obtained products were characterized by both transmission electron microscopy (TEM) and scanning electron microscopy (SEM). By adjusting the reaction conditions, ellipsoidal nanoparticles were formed under acidic conditions, while hollow silica spheres were obtained under alkaline conditions. It is demonstrated that the size distribution of hollow silica spheres was narrower than that of the ellipsoidal nanoparticles. The various vibration modes of different functional groups in the silica materials were revealed by Fourier transform infrared (FTIR) spectroscopy. The two samples were both shown to be amorphous, not crystalline by X-ray diffraction (XRD). A simple diagram of the formation process including the hydrolysis and condensation reactions is given. Furthermore, a probable mechanism for the formation of silica materials under acidic or alkaline conditions is presented, which may be helpful for better understanding the different silica materials obtained under different conditions. 相似文献
967.
Hong Chen Wei Song Feng Zhou Zhongkui Wu He Huang Junhu Zhang Quan Lin Bai Yang 《Colloids and surfaces. B, Biointerfaces》2009,71(2):275-281
Chemical homogeneous poly(dimethylsiloxane) (PDMS) surface with dot-like protrusion pattern was used to investigate the individual effect of surface microtopography on protein adsorption and subsequent biological responses. Fibrinogen (Fg) and fibronectin (Fn) were chosen as model proteins due to their effect on platelet and cell adhesion, respectively. Fg labeled with 125I and fluorescein isothiocyanate (FITC) was used to study its adsorption on flat and patterned surfaces. Patterned surface has a 46% increase in the adsorption of Fg when compared with flat surface. However, the surface area of the patterned surface was only 8% larger than that of the flat surface. Therefore, the increase in the surface area was not the only factor responsible for the increase in protein adsorption. Clear fluorescent pattern was visualized on patterned surface, indicating that adsorbed Fg regularly distributed and adsorbed most on the flanks and valleys of the protrusions. Such distribution and local enrichment of Fg presumably caused the specific location of platelets adhered from platelet-rich plasma (PRP) and flowing whole blood (FWB) on patterned surface. Furthermore, the different combination of surface topography and pre-adsorbed Fn could influence the adhesion of L929 cells. The flat surface with pre-adsorbed Fn was the optimum substrate while the virgin patterned surface was the poor substrate in terms of L929 cells spread. 相似文献
968.
Chengbin Jing Haiyang Shan Chuanjian Zhang Xiaodan Zang Wei Bai Junhao Chu 《Journal of Sol-Gel Science and Technology》2009,51(2):139-145
The solids content and gelation time of aqueous germanate solution were examined in this work. Samples of 5, 10 and 20 mol%
Mn doped Ge were prepared by using the aqueous germanate solution as a liquid Ge precursor. No second phase such as Mn5Ge3 was detected in the 5 and 10 mol% Mn doped samples, implying that Mn ions were uniformly diluted into the Ge host matrix.
The 5 and 10 mol% Mn-doped Ge samples exhibit room-temperature ferromagnetic behaviors that are likely originated from the
RKKY (Ruderman–Kittel–Kasuya–Yosida)-like interaction between the localized Mn ions in the Ge matrix. Therefore, the aqueous
germanate solution can be an alternative sol–gel precursor for preparation of the Mn
x
Ge1−x
diluted magnetic semiconductors (DMSs). 相似文献
969.
A technique for production of nanocrystalline cellulose with a narrow size distribution 总被引:3,自引:0,他引:3
Nanocrystalline cellulose (NCC) was prepared by sulfuric acid hydrolysis of microcrystalline cellulose. A differential centrifugation
technique was studied to obtain NCC whiskers with a narrow size distribution. It was shown that the volume of NCC in different
fractions had an inverse relationship with relative centrifugal force (RCF). The length of NCC whiskers was also fractionized
by differential RCF. The aspect ratio of NCC in different fractions had a relatively narrow range. This technique provides
an easy way of producing NCC whiskers with a narrow size distribution. 相似文献
970.