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81.
Analysis of the polyethylene glycol glucosides and FA esters thereof by atmospheric-pressure ionization MS 总被引:1,自引:0,他引:1
Xin?Jin Jinzong?YangEmail author Bingtao?Tang Minggui?Zhu Ning?Yu Yi?Liu 《Journal of the American Oil Chemists' Society》2003,80(6):519-524
Polyethylene glycol (PEG) glucosides (PEGG) and the PEGG esters of lauric acid were analyzed by atmospheric-pressure ionization
MS (API-MS) with electrospray ionization. Straightforward mass characterization of the complex mixtures could be achieved
without prior chromatographic separation. The constituents were identified on the basis of quasi-molecular ions. Individual
components could be observed as protonated molecular ions [M+H]+ and/or as their NH4
+, Na+, or K+ adducts in positive ion mode. The mass spectrometric investigation showed that mixtures of PEGG consisted of monoglucoside,
diglucoside, polyglucoside, and free PEG. The esterification product is a mixture of two types of nonionic surfactants: PEG-laurates
and PEGG-laurates. The reasons for distortion of the quasi-molecular ion intensities and the stabilization of adduct ions
were discussed. The rapid and highly sensitive API-MS analysis technique proposed here is well suited for direct characterization
of complex mixtures and suitable for development as a routine analytical method. 相似文献
82.
Dietary fat and body weight control 总被引:3,自引:0,他引:3
The global obesity epidemic has heightened the debate about dietary factors contributing to weight gain. Media stories have
promulgated the notion that obesity has increased despite reductions in dietary fat intake. Some have even speculated that
lower dietary fat levels may be driving the rapid rise in weight gain within the population. A close examination of the science
reveals a different picture and supports the hypothesis that dietary fat, within the context of the total dietary composition
consumed by many populations, promotes obesity. Hence, dietary fat control is still an important strategy as part of an overall
approach to body weight management in our modern environment. Dietary fat increases the energy density of foods. Abundant
evidence from preclinical and clinical studies indicates that fat promotes excess energy intake and positive energy balance.
Dietary fat does not promote its own oxidation in the body and is stored efficiently, promoting a positive fat balance. Thus,
both the behavioral and metabolic responses to dietary fat increase the probability of positive energy balance and body fat
gain. Restoring fat balance when consuming diets rich in fat requires increasing the size of the body fat mass, increasing
physical activity, or reducing dietary fat intake. Numerous epidemiologic, preclinical, and controlled clinical studies have
shown that body fat is positively associated with dietary fat intake and that dietary fat manipulation leads to appropriate
changes in body fat mass. Finally, data from the National Weight Control Registry, a database of >3000 individuals who have
successfully maintained a substantial weight loss, indicate that moderating dietary fat intake is a key strategy for long-term
management of body weight. 相似文献
83.
Ai?Min?ZhangEmail author Dong?Cheng?Han Zhi?Qing?Zhu Jung-Woo?Lee Hyun-Ku?RheeEmail author 《Korean Journal of Chemical Engineering》2003,20(4):649-652
Carbon nanotubes were synthesized by chemical vapor deposition and subsequently purified and oxidized by repeated treatment
with nitric acid. After acid treatment the walls of carbon nanotubes became thinner and the surface area increased. The Ni-supported
carbon nanotubes prepared by impregnation were applied to the cracking ofn- heptane to show an excellent activity. This indicates that the carbon nanotubes can serve as a good catalyst support with
high dispersion of metallic components. The optimum Ni loading turned out to be about 5.2 mmol/g. The cracking product was
found to contain mainly small hydrocarbons; thus the Ni-supported carbon nanotubes may be applied as a potential catalyst
to the cracking of heavy hydrocarbons.
A. M. Zhang was a visiting scholar at School of Chemical Engineering, Seoul National University.
This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University. 相似文献
84.
Wanda?Regina?Caly Edna?Strauss Flair?José?CarrilhoEmail author Antonio?Atílio?Laudanna 《Nutrition journal》2003,2(1):10
Objectives
In this work we investigated how immunological dysfunction and malnutrition interact in alcoholic and viral aetiologies of cirrhosis.Methods
To investigate the matter, 77 cirrhotic patients divided in three aetiologies [Alcohol, HCV and Alcohol + HCV) and 32 controls were prospectivelly and sequentially studied. Parameters of humoral immunity (Components 3 and 4 of seric complement and immunoglobulins A M, G and E) and of cellular immunity (total leukocytes and lymphocytes in peripheral blood, T lymphocytes subpopulations, CD4+ and CD8+, CD4+/CD8+ ratio and intradermic tests of delayed hypersensitivity), as well as nutrititional parameters: anthropometric measures, serum albumin and transferrin were evaluated.Results
Multiple statistical comparisons showed that IgM was higher in HCV group; IgG was significantly elevated in both HCV and Alcohol + HCV, whereas for the Alcohol group, IgE was found at higher titles. The analysis of T- lymphocytes subpopulations showed no aetiologic differences, but intradermic tests of delayed hypersensitivity did show greater frequency of anergy in the Alcohol group. For anthropometric parameters, the Alcohol +HCV group displayed the lowest triceps skinfold whereas creatinine – height index evaluation was more preserved in the HCV group. Body mass index, arm muscle area and arm fat area showed that differently from alcohol group, the HCV group was similar to control.Conclusion
Significant differences were found among the main aetiologies of cirrhosis concerning immunological alterations and nutritional status: better nutrition and worse immunology for HCV and vice-versa for alcohol.85.
86.
Indian diets comprising staples such as cereals, millets, and pulses provide 4.8 energy % from linoleic acid (18∶2n−6) but
fail to deliver adequate amounts of n−3 FA. Consumption of long-chain n−3 PUFA such as EPA (20∶5n−3) and DHA (22∶6n−3) is
restricted to those who consume fish. The majority of the Indian population, however, are vegetarians needing additional dietary
sources of n−3 PUFA. The present work was designed to use n−3 FA-enriched spray-dired milk powder to provide n−3 FA. Whole
milk was supplemented with linseed oil to provide α-linolenic acid (LNA, 18∶3n−3), with fish oil to provide EPA and DHA, or
with groundnut oil (GNO), which is devoid of n−3 PUFA, and then spray-dired. Male Wistar rats were fed the spray-dired milk
formulations for 60 d. The rats given formulations containing n−3 FA showed significant increases (P<0.001) in the levels of LNA or EPA/DHA in the serum and in tissue as compared with those fed the GNO control formulation.
Rats fed formulations containing n−3 FA had 30–35% lower levels of serum total cholesterol and 25–30% lower levels of serum
TAG than control animals. Total cholesterol and TAG in the livers of rats fed the formulations containing n−3 FA were lower
by 18–30% and 11–18%, respectively, compared with control animals. This study showed that spray-dried milk formulations supplemented
with n−3 FA are an effective means of improving dietary n−3 FA intake, which may decrease the risk factors associated with
cardiovascular disease. 相似文献
87.
The production of boric acid through reaction of borax crystals with propionic acid was investigated in batch mode. It was
found that the product boric acid precipitates on the solid borax reactant. An increase in the coefficient of variation of
feed crystals resulted in an increase in the time of completion of the reaction. A sharp interface model with variable bulk
fluid concentration of liquid reactant was developed for simulation of the process. The analytical solution of the series
of rate equations involving liquid film, solid boric acid layer and chemical reaction resistances was obtained, and a new
method for simultaneous determination of kinetic parameters was established. The chemical reaction and diffusion through the
solid layer of boric acid were the rate controlling mechanisms. A numerical algorithm was also developed for predicting the
fractional conversion of multisize borax crystals using the mono size kinetic parameters determined according to the proposed
analytical method. 相似文献
88.
P.?N.?Mayamol T.?Samuel C.?Balachandran A.?Sundaresan C.?ArumughanEmail author 《Journal of the American Oil Chemists' Society》2004,81(4):407-413
Several pilot-scale trials reported in this paper, using palm stearin-rice bran oil (PS-RBO) blends, obviously did not contain
trans FA (TFA), whereas the commercial products were found to contain 18–27% TFA. The effects of processing conditions such as
rate of agitation, crystallization temperature, and composition of the blends on the crystal structure of shortenings were
studied. The products were evaluated for their physicochemical characteristics using DSC, X-ray diffraction (XRD), HPLC, and
FTIR techniques. The formulation containing 50% PS and 50% RBO showed melting and cooling characteristics similar to those
of hydrogenated commercial “vanaspati” samples. Analysis of the FA composition revealed that the formulated shortenings contained
15–19% C18∶2 PUFA. Tocopherol and tocotrienol contents of the experimental shortenings were in the range of 850–1000 ppm with oryzanol
content up to 0.6%. XRD studies demonstrated that the crystal form in the shortenings was predominantly the most stable β′
form, and there was less of the undesirable β form. 相似文献
89.
Hong?ZhangEmail author Lars?Saaby?Pedersen Dorther?Kristensen Jens?Adler-Nissen Hans?Christian Holm 《Journal of the American Oil Chemists' Society》2004,81(7):653-658
Lipozyme TL IM-catalyzed interesterification for the modification of margarine fats was carried out in a batch reactor at
70°C with a lipase dosage of 4%. Solid fat content (SFC) was used to monitor the reaction progress. Lipase-catalyzed interesterification,
which led to changes in the SFC, was assumed to be a first-order reversible reaction. Accordingly, the change in SFC vs. reaction
time was described by an exponential model. The model contained three parameters, each with a particular physical or chemical
meaning: (i) the initial SFC (SFC0), (ii) the change in SFC (ΔSFC) from the initial to the equilibrium state, and (iii) the reaction rate constant value (k). SFCo and ΔSFC were related to only the types of blends and the blend ratios. The rate constant k was related to lipase activity on a given oil blend. Evaluation of the model was carried out with two groups of oil blends,
i.e., palm stearin/coconut oil in weight ratios of 90∶10, 80∶20, and 70∶30, and soybean oil/fully hydrogenated soybean oil
in weight ratios of 80∶20, 65∶35, and 50∶50. Correlation coefficients higher than 0.99 between the experimental and predicted
values were observed for SFC at temperatures above 30°C. The model is useful for predicting changes in the SFC during lipase-catalyzed
interesterification with a selected group of oil blends. It also can be used to control the process when particular SFC values
are targeted. 相似文献
90.
Summary
A New heterobifunctional poly(ethylene glycol) (PEG) having a polymerizable
acryloyl group at one end and an isocyanate group at the other end was prepared in
three efficient steps from commercially available t–Boc–PEG–NH2. The end groups
were characterized by 1H NMR and MALDI–TOF–MS spectroscopy. Conjugation of
the resulting PEG onto dextran via stable urethane linkage gave the PEG graft
polymer with an acryloyl group at the free end of the graft chain. 相似文献