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101.
102.
In the ILC(International Linear Collider)main linac, low emittance preservation is the most important issue for beam dynamics study. As the main sources of emittance dilution, the dispersive and wakefield effects were studied in this paper. The theoretical calculations and numerical simulations of these two effects on single-bunch emittance dilution, without any misalignment errors, are presented in detail. 相似文献
103.
应用红外光谱法,研究了不同pH值和Cu2+浓度条件下,合成赤铁矿和三羟铝石吸附Cu2+后表面羟基结构及其特征吸收峰的变化。结果表明:(1)随Cu2+浓度增加,赤铁矿表面H—O—H和OH的变形振动参与了吸附反应,Cu2+强烈地缔结在Fe—O上,形成了Fe—O—(Cu)结构。(2)酸性条件下,H+破坏了赤铁矿表面的O—H结构,NO3-促使弱峰1 131 cm-1的产生。随pH值增大,赤铁矿表面OH-逐渐由伸缩振动转变为变形振动,Fe—OH和Fe3+—O2-结构不断发生改变。(3)三羟铝石对Cu2+的吸附发生在高波位,随Cu2+浓度增大,其表面游离羟基的O—H弯曲振动、水分子的OH-伸缩振动和H—O—H弯曲振动均参与了吸附反应,Al—O基中的Al3+渐被Cu2+取代从而加强了较低波位的振动强度。(4)随pH值增加,三羟铝石Al—OH的弯曲振动和Al—O的伸缩振动逐渐发生着改变,表明吸附Cu2+后,在其表面形成了AlOCu+与AlOCuOH结构。 相似文献
104.
The reactivity of melezitose hydroxyls is studied during tritylation in pyridine. Some novel derivatives of melezitose are prepared. An acetyl is transferred from the 4- to the 6-position after detritylation of 3 and 4. The structures of the products are proved by elemental analysis;
1
H,
13
C, and
1
H-
1
H COSY NMR spectra;IR spectra; and fast-atom bombardment mass spectrometry. 相似文献
105.
High-contrast imaging provided by a coronagraph is critical for the direction imaging of the Earth-like planet orbiting its
bright parent star. A major limitation for such direct imaging is the speckle noise that is induced from the wave-front error
of an optical system. We derive an algorithm for the wave-front measurement directly from 3 focal plane images. The 3 images
are achieved through a deformable mirror to provide specific phases for the optics system. We introduce an extra amplitude
modulation on one deformable mirror configuration to create an uncorrelated wave-front, which is a critical procedure for
wave-front sensing. The simulation shows that the reconstructed wave-front is consistent with the original wave-front theoretically,
which indicates that such an algorithm is a promising technique for the wave-front measurement for the high-contrast imaging.
Supported by the National Natural Science Foundation of China (Grant No. 10873024) 相似文献
106.
107.
108.
109.
Yan-Ni Dou 《Linear algebra and its applications》2011,435(12):3233-3242
In this note, the relationships between the expectation and variance in operator probability theory and numerical range of operators are considered. 相似文献
110.
Jin Li Dou‐sheng Zhang Xiao‐meng Chong Chang‐qin Hu 《Rapid communications in mass spectrometry : RCM》2010,24(14):2143-2150
The structural fragment ions of nine cephalosporins were studied by electrospray ionization quadrapole trap mass spectrometry (Q‐Trap MSn) in positive mode. The influence of substituent groups in the 3‐position on fragmentation pathway B, an α‐cleavage between the C7? C8 single bond, coupled with a [2,4]‐trans‐Diels‐Alder cleavage simultaneously within the six‐membered heterocyclic ring, was also investigated. It was found that when the substituent groups were methyl, chloride, vinyl, or propenyl, fragmentations belonging to pathway B were detected; however, when the substituents were heteroatoms such as O, N, or S, pathway B fragmentation was not detected. This suggested that the [M–R3]+ ion, which was produced by the bond cleavage within the substituent group at the 3‐position, had a key influence on fragmentation pathway B. This could be attributed to the strong electronegativity of the heteroatoms (O, N, S) that favors the production of the [M–R3]+ ion. Moreover, having the positive charge of the [M–R3]+ ion localized on the nitrogen atom in the 1‐position changed the electron density distribution of the heterocyclic structure, which prohibits a [2,4]‐reverse‐Diels‐Alder fragmentation and as a result fragmentation pathway B could not occur. The influence of the substituent group in the 3‐position was determined by the intensity ratio (e/d) of ions produced by fragmentation pathway A, a [2,2]‐trans‐Diels‐Alder cleavage within the quaternary lactam ring, including the breaking of the amide bond and the C6? C7 single bond (ion d), and fragmentation pathway B (ion e). The results indicate that the electronegativity of the substituent group was a key influencing factor of pathway B fragmentation intensity, because the intensity ratio (e/d) is higher for a chlorine atom, a vinyl, or a propenyl group than that of a methyl group. This study provided some theoretical basis for the identification of cephalosporin antibiotics and structural analysis of related substances in drugs. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献