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761.
We propose a conclusive difference observed between the excitation conditions required to observe porphyrins and copper-metallothioneins
in cells and/or tissues using an ordinary fluorescence microscope. We have emphasized the importance of examining the spectral
properties of the emissions to avoid any serious mistakes such as confusing porphyrins with copper-metallothioneins in the
liver and kidneys. However, microspectrophotometry is not a conventional method for either histochemical, cytochemical, or
pathological studies because microspectrophotometers are both expensive and difficult to operate. Therefore, we demonstrate
a simple comparative method using ordinary excitation filter arrangements. When using our technique, it becomes possible to
optically discriminate more accurately between the autofluorescence properties arising from porphyrins and those arising from
copper-metallothioneins. We would like to name our simple technique “Triple Observation Method (TOM)”. 相似文献
762.
763.
针对高分子光波导在制造工艺中波导芯厚度难以控制、芯层和包层的折射率差变动时的随机性以及材料各向异性引起的偏振态依赖性等实际问题,提出了采用抗波导芯厚度误差、抗折射率差变动和抗偏振变动的宽带波导耦合器回路结构的解决方案,给出了设计的理论和方法。在实测数据的基础上,进行了带宽为120nm的3dB氟化聚酰亚胺波导耦合器设计。由该器件的三维BPM仿真结果表明,在上述带宽上,波导芯厚度的变动范围为7~8μm、相对折射率差变动范围为0 24%~0.30%,两个正交偏振态都具有(50±2.0)%功率输出比的良好特性。 相似文献
764.
765.
Takasada Ishii Kaku Uehara Yukihiro Ozaki Mamoru Mimuro 《Photochemistry and photobiology》1999,70(5):760-765
The aggregation behavior of two homologs of bacteriochlorophyll c (BChl c) in various media was investigated for the effects of pH and salt, and the corresponding structures were analyzed by Fourier transform (FT)-IR spectroscopy. R-[P, E] BChl cF (31-R-form of BChl c with a propyl group at the C-8 position and an ethyl group at the C-12 position) and R-[E, E] BChl cF (31-R-form of BChl c with two ethyl groups at positions C-8 and C-12) were isolated from the green sulfur bacterium Chloro-bium limicola. Aggregates of each homolog showed a pH-dependent shift of the absorption maximum; at low pH, the peak moved to the red. This tendency was also revealed by circular dichroic spectra. A similar red shift of the peak was also induced by a high concentration of salt (NaCl) or buffer for both homologs. The FT-IR spectrum indicates that at low pH, both homologs formed a rather amorphous aggregate. On the other hand, a regular structure of R-[P, E] BChl cF was indicated in an acetone-water mixture. This structure was stabilized by a triangular interaction among three pigment molecules through the Mg-OH (3>) O = C (131) linkage. This structure was not found for R-[E, E] BChl cF. These results indicate that the replacement of the side chain at the C-8 position on the macrocycle induces a change in aggregation behavior. A possible heterogeneity of the in vivo rod structure of chlorosomes in green sulfur bacteria is discussed based on the above results. 相似文献
766.
767.
Polypropylene (PP) prepared with a MgCl2/TiCl4-Et3Al/Ph2Si(OMe)2 catalyst system was fractionated by temperature rising elution fractionation method in order to investigate the effect of Ph2Si(OMe)2 as an external donor (ED). This PP had a broad and continuous distribution of tacticity. In comparison to the system without donor, however, ED brought a decrease of lower isotactic portions and an increase of higher isotactic ones simultaneously to the resulting polymer. The latter portions were eluted at higher temperature than the corresponding component obtained without donor, showing that the higher isotactic PP was newly produced by ED. 相似文献
768.
769.
Kiyoshi Suzuki Akihiro Goto Motoki Takayama Akio Muramatsu Mamoru Nomura 《Macromolecular Symposia》2000,155(1):199-212
In order to clarify the kinetic role of oil‐soluble initiators in microemulsion polymerization, the oil‐in‐water (O/W) microemulsion polymerizations of styrene are carried out using four kinds of azo‐type oil‐soluble initiators with widely different water‐solubility. The results are compared with those observed when a water‐soluble initiator, potassium persulfate (KPS) is used. For all the oil‐soluble initiators used, the molecular weight of polymers and the average size of polymer particles do not change with the monomer conversion and the initial initiator concentration. The monomer conversion is expressed as a function of ri0.5t, where ri is the rate of radical generation in the whole reaction system and t is the reaction time. These characteristics are quite the same as those observed when KPS is used as an initiator. When the polymerizations are carried out with the rate of radical generation in the whole reaction system fixed at the same value, the rates of polymerization are almost the same for all the oil‐soluble initiators employed, irrespective of their water‐solubility, but are significantly lower (ca. 1/3) than that with KPS. Then, the following conclusions are given: (1) The radicals generated not only in the aqueous phase, but also in the micelle and polymer particle phase are almost equally effective for the polymerization. However, (2) only a small portion (ca. 1/9) of the radicals generated in both phases participate in the polymerization. (3) Bimolecular termination of a growing radical in the polymer particle with an entering radical and with a pair of radicals generated in the polymer particles is negligible, and hence, the molecular weight of polymers is determined only by chain transfer to monomer. 相似文献
770.
Various diacyl sulfides were synthesized by reaction of acyl chlorides with LiAlHSH. Reaction of glutaryl chloride with LiAlHSH afforded glutaric thioanhydride. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:633–635, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10217 相似文献