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991.
We have developed a method to identify and map the internationally most visible research topics occurring in the social and
behavioral sciences, as well as the topics which changed most over a decade. Methods and data relevent to a portfolio analysis
of national research efforts are described. Keywords used by authors in scientific or scholarly publications provide a window
on scientific developments and changes in scientific research. Using an interdisciplinary database, the SSCI, developments
in publications were traced world-wide and for the US, UK, France, Germany, and the Netherlands. We compared two periods:
1981–85 and 1986–90 We discuss the major substantive developments occurring during 1981–1990, as visible in maps depicting
both topics and disciplines. It is shown that the maps, enriched with scientometric indicators of strengths and weaknesses
of national research efforts, can be important tools for science policy. The findings indicate that the research front on
many topics in both social and behavioral sciences is international in the late 1980s. 相似文献
992.
Journal of Signal Processing Systems - 相似文献
993.
994.
D. Van Baelen K. Van den Dungen J. Degreve C. Vandecasteele 《Chemical engineering science》2005,60(6):1583-1590
In this study, pervaporation experiments were performed with methanol-water mixtures, ethanol-water mixtures, IPA (isopropyl alcohol)-water mixtures, and acetic acid-water mixtures, over the complete concentration range allowed by the membrane (Pervap 2201, Sulzer). The results of the three water-alcohol mixtures are compared to investigate the influence of molecular weight and polarity on the permeation behavior. The results show that ethanol and IPA have a similar permeation behavior, whereas methanol shows a different behavior. This can be explained by the relatively high polarity of methanol, which makes methanol sorption competitive with water sorption. The IPA-water mixtures are compared with the acetic acid-water mixtures. IPA and acetic acid have approximately the same molecular weight, but contain a different functional group. The acetic acid-water mixtures have a higher total flux than the IPA-water mixtures. Moreover, the partial acetic acid flux is higher than the partial IPA flux. Acetic acid contains a carbonyl group, which has a high capacity of forming hydrogen bonds with the alcohol groups of the PVA (polyvinyl alcohol) top layer. Moreover, it is a large molecule, causing high swelling resulting in a high permeation flux and a low separation factor. The behavior of the acetic acid-water mixtures shows more resemblance to the methanol-water mixtures than to the IPA-water mixtures. This suggests that the polarity and functional group of the different feed components is more important than the molecular size. 相似文献
995.
Coulson Seana; Federmeier Kara D.; Van Petten Cyma; Kutas Marta 《Canadian Metallurgical Quarterly》2005,31(1):129
Researchers using lateralized stimuli have suggested that the left hemisphere is sensitive to sentence-level context, whereas the right hemisphere (RH) primarily processes word-level meaning. The authors investigated this message-blind RH model by measuring associative priming with event-related brain potentials (ERPs). For word pairs in isolation, associated words elicited more positive ERPs than unassociated words with similar magnitudes and onset latencies in both visual fields. Embedded in sentences, these same pairs showed large sentential context effects in both fields. Small effects of association were observed, confined to incongruous sentences after right visual hemifield presentation but present for both congruous and incongruous sentences after left visual hemifield presentation. Results do not support the message-blind RH model but do suggest hemispheric asymmetries in the use of word and sentence context during real-time processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
996.
997.
Willem J.H. Van Groenendaal Jack P.C. Kleijnen 《Reliability Engineering & System Safety》1997,57(1):91-102
The feasibility of large investment projects (such as gas transmission and power system projects) has many aspects. Usually, this problem cannot be modeled as a single optimization problem; instead, the multiple aspects (demand, supply, prices, investment costs) are modeled separately. Each aspect may require a large, nonlinear submodel. The results of such a submodel can often be summarized by one or a few variables, which combine all the submodel's information; for example, total demand is the sum of the demand per customer type, each type being modeled separately. Traditionally, the feasibility of the investment project is then judged by combining the results of the various submodels for the ‘base case’ values of all model inputs.This base case information, however, is not sufficient for the decision makers; they also like to know the economic risk they are taking. To assess this risk on the project level (Hertz, D. B., Risk analysis in capital investment. Harvard Business Review, 1964, 95–106) developed a method known as risk analysis. This method is based on the estimated probability distribution of a project's net present value (NPV). This distribution is obtained by introducing distributions for the model inputs. The project's economic risk is then. expressed as the probability of a negative NPV exceeding a critical value (say) α. Nowadays this approach is becoming popular, because many software packages (such as @RISK and Crystal Ball) facilitate such a risk analysis. Although Hertz's risk analysis is appealing, it has a number of theoretical and practical flaws, which may lead to wrong conclusions. These flaws are discussed in this paper.From a modelling point of view, Hertz's risk analysis is similar to analysing the technological or operational risk of an investment. However, economic risk and technological risk are different concepts that require different analyses. In this paper these differences are discussed and it is shown that Hertz's risk analysis does not measure what is normally meant by a project's economic risk. Furthermore, the information requirements for the application of risk analysis to large investment projects are formidable; this makes the results of Hertz's investment analysis unreliable. Less information is required by sensitivity analysis based on the statistical design of experiments (such as 2k−P designs); this analysis is more robust, and leads to results that better satisfy the information needs of decision makers. 相似文献
998.
Current situation on regulations for mycotoxins. Overview of tolerances and status of standard methods of sampling and analysis 总被引:3,自引:0,他引:3
H P Van Egmond 《Food Additives & Contaminants》1989,6(2):139-188
A worldwide enquiry was undertaken in 1986-1987 to obtain up-to-date information about mycotoxin legislation in as many countries of the world as possible. Together with some additional data collected in 1981, information is now available about planned, proposed, existing or absence of legislation in 66 countries. Details about tolerances, legal bases, responsible authorities, prescribed methods of sampling and analysis and disposition of commodities containing inadmissible amounts of mycotoxins, are given. The information concerns aflatoxins in foodstuffs, aflatoxin M1 in dairy products, aflatoxins in animal feedstuffs, and other mycotoxins in food- and feedstuffs. In comparison with the situation in 1981, limits and regulations for mycotoxins have been expanded in 1987 with more countries having legislation (proposed or passed) on the subject, more products, and more mycotoxins covered by this legislation. The differences between tolerances in the various countries are sometimes quite large, which makes harmonization of mycotoxin regulations highly desirable. 相似文献
999.
John W Cone Wilhelmina Clin-Theil Aart Malestein Arie Th van 't Klooster 《Journal of the science of food and agriculture》1989,49(2):173-183
The degradability of starch from various feedstuffs was investigated in vitro by incubation of 500-mg amounts in 50 ml of a 3:1 rumen fluid/buffer solution at 39°C for 6 h. The rumen fluid was obtained from one of three cows fed on hay or hay and concentrate. The degree of degradation after 6 h incubation varied strongly for the 23 feedstuffs investigated. The degradation of starch from the same feedstuff in rumen fluid from a hay-fed cow was significantly lower than in rumen fluid from a concentrate-fed cow. It seemed that differences in degradability between feedstuffs were not determined by the ration of the donor cow, but merely by the properties of the starch. Processed feedstuffs showed a higher degradation of their starch than the unprocessed feedstuffs, independent of the ration of the donor cow. Particle size influenced degradation, but not of the starch of tapioca meal. A fairly constant ranking in degradability between the various feedstuffs was found. Fermentation of mixtures of feedstuffs showed about the same rate of degradation as found for the single products. Only when great differences in the degree of degradability existed was the degradation of the total starch enhanced. The time of collection of rumen fluid strongly influenced the in-vitro degradation of starch. 相似文献
1000.
L. J. Van Poolen R. T. Jacobsen M. Jahangiri 《International Journal of Thermophysics》1986,7(3):513-524
A comparison of the prediction of the critical density for ethylene and oxygen from available coexistence density values using three methods is presented. The conventional rectilinear diameter, the rectilinear diameter with an additional term to represent the postulated curvature near the critical point, and the critical liquid volume fraction were each utilized to predict critical density values for ethylene and oxygen. The correlating functions and fitted constants for the three techniques are given for different ranges of saturation density values. The accepted saturation lines for ethylene and oxygen calculated from new correlations of thermodynamic properties for these fluids were used in this study. The critical density of ethylene was predicted using coexistence density values from 220 to 230 K and from 220 to 282.34 K. Similarly, the critical density for oxygen was predicted using coexistence densities from 100 to 116 K, from 100 to 154.004 K, and from 100 to 154.571 K. Values of the critical density predicted using the three methods are compared with the accepted critical density values for these fluids. The ability of the three methods to predict accurate critical density values using saturation densities at temperatures removed from the critical point is assessed.Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A. 相似文献