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1.
Yi Jin Chieko Toeda Takeo Kawaguchi Toshinobu Seki Kazuhiko Juni 《Drug development and industrial pharmacy》1996,22(7):653-658
Permeation of zidovudine (3'-azido-3'-deoxythymidine, AZT) and probenecid from oily bases containing an alcohol through rat skin was examined. Isopropyl myristate (IPM), as an oily vehicle, showed a penetration enhancing effect for AZT and probenecid. Ethanol, n-propanol, and n-butanol were used as additives in IPM and were examined for their own permeation and the enhancing effect on the permeation of AZT and probenecid. The skin permeation of AZT and probenecid from IPM was enhanced by addition of the alcohol in IPM. The degree of the enhancement was decreased with increasing lipophilicity of the alcohol used. me permeation rate of the drug from those systems was shown to be governed by penetration-enhancing effects of the oily base and alcohol, and the penetration of the alcohol itself through the skin. 相似文献
2.
Transdermal absorption of zidovudine (AZT) from an ethanol-isopropyl myristate (IPM) mixed system was examined in rats. For comparison of bioavailability (BA) after topical applications, 0.25 ml of the ethanol/IPM system containing 40% ethanol and 60 mM AZT was applied as a standard formulation. Values of the area under the plasma concentration-time curves of AZT for 8 hr (AUC0-8), as indices of BA, following application of various formulations were compared with that of the standard formulation. Then the influence of content of the drug and ethanol, and application volume of the system was evaluated. BA was effectively improved only when the total amount of ethanol applied on the skin was increased. On the other hand, simultaneous transdermal application of AZT and probenecid increased the AU0-8, of AZT without necessitating the increase in ethanol content in the formulation. In addition, coadministered probenecid improved cerebrospinal fluid/plasma concentration ratio of AZT. 相似文献
3.
Summary Cationic polymerization of p-methoxystyrene initiated by HI/ZnI2 in toluene afforded living polymers not only at low temperature (–15°C) but at room temperature (+25°C) as well. The number-average molecular weight of the polymers was directly proportional to monomer conversion and in excellent agreement with the calculated value assuming that one polymer chain forms per unit hydrogen iodide. On addition of a fresh feed of monomer at the end of the first-stage polymerization, the added feed was smoothly polymerized at nearly the same rate as in the first stage; the polymer molecular weight further increased in direct proportion to monomer conversion and was close to the calculated value for living polymer. Throughout these reactions, the molecular weight distribution of the polymers stayed very narrow (¯Mw/¯Mn<1.1). This is the first example of living cationic polymerizations of styrene derivatives that proceed even at room temperature. 相似文献
4.
This paper deals with the epoxide treatment of silk fabrics by the pad/batch method. The optimum reaction conditions, i.e., NaOH concentration, and reaction temperature were 2.5 g/L and 30°C, respectively. A weight gain of 8.5% was attained at a reaction time of 6 h. This value slightly increased to 10% after 24 h. The reactivity of tyrosine and basic amino acid residues was dependent on the reaction time and did not significantly differ from the results of epoxide-treated silk fiber by the conventional method in tetrachloroethylene. The moisture regain slightly decreased at 4% weight gain and then increased with the epoxide content, exceeding the value of the untreated control. The crease recovery of the epoxide-treated silk fabrics measured in the wet state was significantly improved, whereas that in the dry state was almost unchanged. The rate of photoyellowing of the epoxide-treated silk fabrics by the pad/batch method was reduced significantly compared with that of the untreated control. Among the mechanical properties, elongation at break and tensile modulus remained unchanged, whereas the tensile strength slightly increased following the epoxide reaction. The thermal properties were evaluated by DSC and TGA and on the basis of the dynamic viscoelastic measurements. The DSC curve of the epoxide-treated sample showed a slight increase of the decomposition temperature of silk fibroin. The rate of weight loss determined by TGA remained unchanged regardless of the chemical modification, whereas the peak of loss modulus became broader and shifted to lower temperature. The X-ray diffractograms showed that the crystalline structure of silk fibers was not affected by the reaction with epoxides. © 1993 John Wiley & Sons, Inc. 相似文献
5.
Summary Well-defined living polymers of isobutyl vinyl ether were obtained in the polymerization initiated with ethylaluminum dichloride (EtAlCl2) in conjunction with a stoichiometric excess of dioxane (5–10 vol%) in n-hexane at 0°C. Under these conditions, the number-average molecular weight of the polymers increased in direct proportion to monomer conversion, while the molecular weight distribution stayed narrow (Mw/Mn = 1.1–1.25). In sharp contrast, the EtAlCl2-initiated polymerization in the absence of dioxane led to non-living polymers with a broad molecular weight distribution. It was concluded that the propagating carbocation is stabilized not by the counteranion but by an externally added basic compound (dioxane) that strongly interacts with the active end. 相似文献
6.
Summary The first example of the living cationic polymerization of isobutyl vinyl ether via the phosphate counteranion has been achieved in toluene below 0°C with a new initiating system that consists of diphenyl phosphate and zinc iodide, (C6H50)2P(0)0H/ZnI2. The number-average molecular weight of the polymers increased in direct proportion to monomer conversion, and was in excellent agreement with the calculated value assuming that one polymer chain forms per unit diphenyl phosphate. On addition of a fresh feed of monomer at the end of the polymerization, the added feed was smoothly polymerized at nearly the same rate as in the first stage, and the polymer molecular weight further increased in direct proportion to monomer conversion. Throughout the reaction, the molecular weight distribution of the polymers stayed very narrow (¯M/¯Mn 1.1). At room temperature (+25 °C), however, the molecular weight distribution of the polymers slightly broadened (¯Mw/¯Mn 1.2) at high conversions where the polymer molecular weight became smaller than the calculated value. Evidently, the (C6H50)2-P(0)0H/ZnI2 system indeed generates a propagating species of a long life-time at room temperature, but the perfectly living polymerization by this system operates below 0°C.Living cationic polymerization of vinyl ethers by electrophile 相似文献
7.
Toshinobu Yoko Toshio Nishiwaki Kanichi Kamiya Sumio Sakka 《Journal of the American Ceramic Society》1991,74(5):1104-1111
Cu+ ⇌ R+ (R = Li, Na, and K) ion exchange experiments were conducted for 20R2 O·10Al2 O3 ·70SiO2 glasses in molten CuCl at 550°C in air and nitrogen atmospheres. The depth profiles of the copper incorporated into glasses were determined with an electron microprobe X-ray analyzer. The total amount of diffusing copper, M t , strongly depended on the type of alkali ion in the glass and the ion-exchange atmosphere; i.e., M t increased with increasing cationic size in the order Li < Na < K and M t was greater in air than in nitrogen. The Cu ⇌ R+ ion exchange kinetics are discussed in detail. 相似文献
8.
Nuclear magnetic resonance (n.m.r.) and circular dichroism of in methylene were investigated. In methylene chloride-d2 was found to consist of nearly all-trans amide bonds and assume a stable secondary structure. Trace amounts of cis amide bonds were also present. The addition of dichloroacetic acid destroyed the secondary structure and induced a drastic change of the n.m.r. spectrum, which was similar to that observed with the monomeric amide, dimethylamide. In comparison of the polymer with the monomeric amide, it was concluded that the transition of was caused by the isomerization of amide bonds. The complex n.m.r. spectrum was interpreted in terms of the distribution along the polymer chain of various non-planar amide links as well as planar cis and trans amide links. The difference of the mechanism of conformational transition between poly(amino acid) and poly(imino acid) is also discussed. 相似文献
9.
Kazufumi Tsujimoto Toshinobu Sasa Kenji Nishihara Takakazu Takizuka Hideki Takano 《Progress in Nuclear Energy》2000,37(1-4):339-344
The accelerator-driven transmutation system has been studied at the Japan Atomic Energy Research Institute. This system is a hydrid system which consists of a high intensity accelerator, a spallation target and a subcritical core region. In the conceptual design study, two types of system concepts, sodium cooled and lead-bismuth cooled system, are being studied. In this study, we fucus on our lead-bismuth cooled accelerator-driven transmutation system to investigate basic characteristics. The fuel compositions were optimized for efficient transmutation of minor actinide. The transmutation of long-lived fission products was also considered. 相似文献
10.
Koichiro Ishibashi Hisayuki Higuchi Toshinobu Shimbo Kunio Uchiyama Kenji Shiozawa Naotaka Hashimoto Shuji Ikeda 《Analog Integrated Circuits and Signal Processing》1999,20(2):85-94
There are various kinds of analog CMOS circuits in microprocessors. IOs, clock distribution circuits including PLL, memories are the main analog circuits. The circuit techniques to achieve low power dissipation combined with high performance in newest prototype chip in the Super H RISC engines are described. A TLB delay can be decreased by using a CAM with a differential amplifier to generate the match signal. The accelerator circuit also helps to speed up the TLB circuit, enabling single-cycle operation. A fabricated 96-mm2 test chip with the super H architecture using 0.35-m four metal CMOS technology is capable of 167-MHz operation at 300 Dhrystone MIPS with 2.0-W power dissipation. 相似文献