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71.
Benedikt Ley Corinna Ogonowski Jan Hess Tim Reichling Lin Wan Volker Wulf 《Behaviour & Information Technology》2014,33(8):815-828
Technological infrastructure at home is changing continuously and is becoming increasingly interconnected. Media devices, including the TV set, provide access to the Internet and offer manifold opportunities to consume media on demand. Additionally, personal devices, such as smartphones, also enable flexible consumption and sharing of media. Questions about how these technologies change the user's media usage and how these changes affect the social structure of a household, however, remain largely unanswered. In order to gain insight into the adoption of new technologies into daily routines, we explored these changes in respect of people's media usage in a qualitative long-term Living Lab study. We will present findings regarding personal routines, flexible integration of new devices into existing practices, influences on households as social systems and related issues in device access and collective use. We will highlight potentials and conflicts regarding device shifts and roles; restrictions in device access; social influences in the living room; and individual changes in media consumption. 相似文献
72.
The vapour pressure of solids can be obtained using a number of methods, including the Knudsen effusion method, the Knudsen torque-effusion method and a transpiration method. Each method has benefits and disadvantages. Reported is a comparison of vapour pressure data for two compounds, quinizarin and leuco -quinizarin, using a transpiration method and a recently developed method based on thermogravimetry. Thermogravimetry provided vapour pressure–temperature dependence data for each compound with expediency and in agreement with the transpiration method. 相似文献
73.
Lipids of seven cereal grains 总被引:1,自引:0,他引:1
Grain samples of representative varieties of barley, corn, oats, rye, sorghum, triticale, and wheat grown commercially in the north central US were analyzed. Chemical constituents of the varieties studied are presented to provide an overview of their characteristics. Lipids of the milled grain samples were solvent extracted, classified by silicic acid column chromatography, and separated by thin layer chromatography. Fatty acid composition of the total lipid was determined by gas liquid chromatography and the fatty acid content was determined by saponification and extraction. Total lipid content of the grains ranged from 2.3% for ‘Polk’ wheat to 6.6% for ‘Chief’ oats. Lipid composition varied considerably. The row crops, corn and sorghum, have a high neutral lipid and low glycolipid content. The small grain varieties have a more balanced distribution among neutral lipids, glycolipids, and phospholipids. Fatty acid composition of the total lipid was similar for all grains. Minor qualitative differences were noted among the lipid classes of the 7 cereals. 相似文献
74.
M. R. Kamal N. R. Demarquette R. A. Lai-Fook T. A. Price 《Polymer Engineering and Science》1997,37(5):813-825
The commonly used thermodynamic theories (mean field theory and the square gradient theory) to predict interfacial tension between polymers have been modified. The results of these theoretical developments have not yet been fully tested and compared to experimental data. In this paper, experimental data for the effects of temperature, molecular weight, and molecular weight dispersity on interfacial tension for polypropylene/polystyrene polymer pairs are compared with the predictions of the new versions of the above theories. To evaluate these theories, it is necessary to know the Flory-Huggins interaction parameter for the polymer pairs studied. The relation correlating the Flory-Huggins interaction parameter to the Hildebrand solubility parameter was not suitable for evaluating the theoretical predictions of interfacial tension. Instead, the Flory Huggins interaction parameter was expressed as the sum of an enthalpic contribution, χH, and entropic contribution, χs. In the absence of reliable experimental values, a method was developed to evaluate the two contributions, based on interfacial tension data. The procedure provided an interaction parameter that is allowed to depend on molecular weight. When this approach was used, the predictions of only the new version of the square gradient theory were in good agreement with the experimental data for the influence of temperature and molecular weight on interfacial tension. However, the theory predicted the effect of polydispersity on interfacial tension only at high temperatures. 相似文献
75.
C. Price P.A. Canham M.C. Duggleby T.deV. Naylor N.S. Rajab R.B. Stubbersfield 《Polymer》1979,20(5):615-619
Ultramicroscopy studies have been made of micelle formation by two poly(styrene)-poly(isoprene) block copolymers in organic solvents (N,N-dimethylacetamide and n-decane respectively) and a poly(l-glutamic acid)-poly(l-leucine) block copolymer in an aqueous solution of 0.2M NaCl at pH = 4.0. The technique provides a method of determining the number-average translational diffusion coefficient) , of association colloids and leads, via the Stokes-Einstein relation, to a measure of the number-average of the reciprocal hydrodynamic radius for spherical particles. Particles having a radius less than approximately 30 nm were too small to be detected by the technique.The ultramicroscopy results were compared with data obtained by laser light scattering photon correlation spectroscopy which provides a measure of the z-average translational diffusion coefficient. . An additional comparison was made by carrying out measurements on two well-characterized poly(styrene/divinyl benzene) latices. 相似文献
76.
ZengShun Chen JianTing Zhou Kim Tim Tse Gang Hu Yong Li Xu Wang 《中国科学:技术科学(英文版)》2016,59(11):1759-1770
In this paper, bridge alignment control with considering dynamic train loads was experimentally and theoretically investigated. Analytical process of bridge dynamics and the self-adaptive Kalman filter bridge alignment control method with considering the dynamic train loads were briefly introduced. The static measurement, the dynamic test, the field alignment measurement as well as the finite element analysis (FEA) of the second longest rail transit cable-stayed bridge in the world were carried out. Based on the results, the train dynamic load effect on the bridge alignment was obtained quantitatively. Subsequently, alignment control of the rail transit bridge with considering this effect using a self-adaptive Kalman filter method was analyzed. The results show that: (a) the dynamic train loads have effects on alignment control of the bridge and therefore cannot be neglected; (b) the self-adaptive Kalman filter method is applicable and reliable for alignment control of bridges during construction. The analytical method and whole process contribute to develop a related specification and further engineering applications. 相似文献
77.
Susana P. Alves Payam Vahmani Cletos Mapiye Tim A. McAllister Rui J. B. Bessa Michael E. R. Dugan 《Lipids》2021,56(6):539-562
Trans (t) fatty acids (TFA) from partially hydrogenated vegetable oils (i.e., industrial trans) have been phased out of foods in many countries due to their promotion of cardiovascular disease. This leaves ruminant-derived foods as the main source of TFA. Unlike industrial TFA where catalytic hydrogenation yields a broad distribution of isomers, ruminant TFA are enzymatically derived and can result in enrichment of specific isomers. Comparisons between industrial and ruminant TFA have often exonerated ruminant TFA due to their lack or at times positive effects on health. At extremes, however, ruminant-sourced foods can have either high levels of t10- or t11-18:1, and when considering enriched sources, t10-18:1 has properties similar to industrial TFA, whereas t11-18:1 can be converted to an isomer of conjugated linoleic acid (cis(c)9,t11-conjugated linoleic acid), both of which have potential positive health effects. Increased t10-18:1 in meat-producing ruminants has not been associated with negative effects on live animal production or meat quality. As such, reducing t10-18:1 has not been of immediate concern to ruminant meat producers, as there have been no economic consequences for its enrichment; nevertheless at high levels, it can compromise the nutritional quality of beef and lamb. In anticipation that regulations regarding TFA may focus more on t10-18:1 in beef and lamb, the present review will cover its production, analysis, biological effects, strategies for manipulation, and regulatory policy. 相似文献
78.
Arvind Agarwal Tim McKechnie Sudipta Seal 《JOM Journal of the Minerals, Metals and Materials Society》2002,54(9):42-44
Research Summary Nanostructured ceramics and their composites possess improved properties such as tensile strength, fatigue
strength, hardness, and wear resistance. Freestanding, near-net shape, nanostructured Al2O3 components can be synthesized via plasma-spray forming. In this study, plasma-spray parameters were optimized and an innovative
substrate cooling technique was developed to retain nanosize Al2O3 in the spray deposit. Nanosize Al2O3 particles were partially melted and trapped between the fully melted coarser, micrometersize Al2O3grains. Densification of the spray-deposited Al2O3occurred via solidification and sintering. A similar processing approach can be adopted for fabrication of near-net shapes
of a variety of nanostructured materials (metals, ceramics, and intermetallics) and their combinations by selecting suitable
powder-treatment and plasmaspray parameters. 相似文献
79.
As the number of messages and social relationships embedded in social networking sites (SNS) increases, the amount of social information demanding a reaction from individuals increases as well. We observe that, as a consequence, SNS users feel they are giving too much social support to other SNS users. Drawing on social support theory (SST), we call this negative association with SNS usage ‘social overload’ and develop a latent variable to measure it. We then identify the theoretical antecedents and consequences of social overload and evaluate the social overload model empirically using interviews with 12 and a survey of 571 Facebook users. The results show that extent of usage, number of friends, subjective social support norms, and type of relationship (online-only vs offline friends) are factors that directly contribute to social overload while age has only an indirect effect. The psychological and behavioral consequences of social overload include feelings of SNS exhaustion by users, low levels of user satisfaction, and a high intention to reduce or even stop using SNS. The resulting theoretical implications for SST and SNS acceptance research are discussed and practical implications for organizations, SNS providers, and SNS users are drawn. 相似文献
80.
Librarians can improve their online tutorials by borrowing usability testing techniques from the computer science field to improve the human-computer interface. This study involved a multimethod usability test of librarian-created tutorials to determine what students learned, how they felt on several affective questions, and what they suggested for improving the tutorials. Results of pre- and post-tests showed that student knowledge increased, and surveys and focus group findings lean to several suggestions for improving engagement and placing tutorials where they will be most effective. This case study demonstrates the value of user input to improve the effectiveness of online instruction for information literacy. 相似文献