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991.
The deactivation model was used to explain kinetics underlying the conversion reaction of trona to NaHCO3 (sodium bicarbonate). The model showed good agreement with the experimental data obtained from the conversion reaction of trona to NaHCO3. It gave the value of 0.94 as an average correlation coefficient with the experimental data. However, at lower temperature, the model was in poor agreement with the data. This would be related to the structural variation of trona particles at the lower temperature. A trona particle is initially nonporous and then it begins to crack. This structural variation creates more surface area for the reaction with CO2 and water vapor. However, at the lower temperature, the fissures on the surface of the particles are not fully developed during the beginning of the reaction. As a consequence, the level of the conversion of trona at the lower temperature is low during the beginning of the reaction and the time to approach the complete conversion is shorter as temperature increases. However, since the deactivation model does not include the term articulating the degree of the structural variation during the reaction, it does not fit well to the experimental data at the lower temperature. The deactivation rate constant, kd is strongly temperature dependent and the change of the slope suggests the reaction mechanism changes as the reaction temperature increases. 相似文献
992.
The authors examined (a) whether core self-evaluations in adolescence and young adulthood predict income at midlife and (b) whether people with positive core self-evaluations are more likely to capitalize on advantages resulting from family socioeconomic status and academic achievement, resulting in even higher levels of income at midcareer. The sample consisted of participants from the National Longitudinal Survey of Youth, a national probability sample that first surveyed participants in 1979. The authors found that core self-evaluations and family socioeconomic status and academic achievement predict income and that, furthermore, high core self-evaluations enhance the benefits derived from these factors. Overall, it appears that individuals with positive core self-evaluations are particularly adept at translating early advantages into later economic success. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
993.
Over the past decade, electrospinning has grown from a small niche process to a widely used fiber formation technique. Applying a strong electric potential on a polymer solution or melt produces nanoscale fibers. These nanofibers form non‐woven textile mats, oriented fibrous bundles and even three‐dimensional structured scaffolds, all with large surface areas and high porosity. Major applications of electrospun membranes include tissue engineering, controlled drug delivery, sensing, separations, filtration, catalysis and nanowires. This perspective article highlights many recent advances in electrospun fibers for functional applications, with an emphasis on the advantages and proposed technologies for these non‐woven fibrous scaffolds. Copyright © 2007 Society of Chemical Industry 相似文献
994.
Disambiguating Japanese compound verbs 总被引:1,自引:0,他引:1
The purpose of this study is to disambiguate Japanese compound verbs (JCVs) using two methods: (1) a statistical sense discrimination method based on verb-combinatoric information, which feeds into a first-sense statistical sense disambiguation method and (2) a manual rule-based sense disambiguation method which draws on argument structure and verb semantics. In evaluation, we found that the rule-based method outperformed the statistical method at 94.6% token-level accuracy, suggesting that fine-grained semantic analysis is an important component of JCV disambiguation. At the same time, the performance of the fully automated statistical method was found to be surprisingly good at 82.6%, without making use of syntactic or lexical semantic knowledge. 相似文献
995.
Friso H. W. Van Amerom Ashish Chaudhary Michelle Cardenas John Bumgarner R. Timothy Short 《Chemical Engineering Communications》2008,195(2):98-114
A new microfabrication method for micro-cylindrical ion trap (μ-CIT) mass spectrometer arrays (ro, zo ≅ 360 μm) is presented along with a strategy for incorporating integrated high-field emission electron sources for ionization. Simulations of the performance of μ-CITs were used to guide the geometrical design of the array, and process flows for microfabrication in silicon were developed and optimized for reduced capacitance. The microfabrication process is described in detail along with initial test results. Field emission sources were also fabricated in silicon using an edge-to-edge emission strategy to improve robustness in moderate vacuum environments. Simulations were also used to guide the design of the field emitter arrays. The microfabrication process is described and initial field emission data are presented. Strategies for further optimization and integration are also briefly discussed. 相似文献
996.
997.
Christopher C. Tsai Gunny Lee Fred Raab Gregory J. Norman Timothy Sohn William G. Griswold Kevin Patrick 《Mobile Networks and Applications》2007,12(2-3):173-184
Obesity is a major public health challenge with over 65% of US adults either overweight or obese. Estimated annual costs of obesity are $78.5 billion. Self-monitoring is a critical skill for successful weight management. However, self-monitoring is labor-intensive, and compliance is often difficult. In this paper, the authors describe the Patient-Centered Assessment and Counseling Mobile Energy Balance (PmEB) mobile phone application that allows users to self-monitor caloric balance in real time. The application was developed and applied in a four-phase iterative research and development methodology. A usability study and a preliminary feasibility study were conducted. The 1 month feasibility study measured compliance and satisfaction among a sample of 15 participants randomized to one of three groups: (1) a paper diary group, (2) a PmEB group with one daily prompt, and (3) a PmEB group with three daily prompts. PmEB scored highly on usability, compliance, and satisfaction. In addition, mobile phone group users scored PmEB the same as or better than Paper Group members scored the paper diary in nearly all categories. Thematic analysis of comments revealed very positive reviews of PmEB as well as areas for improvement. PmEB is both usable and feasible for weight management self-monitoring, and the iterative pilot study methodology was effective in improving its usability. 相似文献
998.
Matthew R. Walsh Steve H. Hancock Scott J. Wilson Shirish L. Patil George J. Moridis Ray Boswell Timothy S. Collett Carolyn A. Koh E. Dendy Sloan 《Energy Economics》2009,31(5):815-823
Economic studies on simulated gas hydrate reservoirs have been compiled to estimate the price of natural gas that may lead to economically viable production from the most promising gas hydrate accumulations. As a first estimate, $CDN2005 12/Mscf is the lowest gas price that would allow economically viable production from gas hydrates in the absence of associated free gas, while an underlying gas deposit will reduce the viability price estimate to $CDN2005 7.50/Mscf. Results from a recent analysis of the simulated production of natural gas from marine hydrate deposits are also considered in this report; on an IROR basis, it is $US2008 3.50–4.00/Mscf more expensive to produce marine hydrates than conventional marine gas assuming the existence of sufficiently large marine hydrate accumulations. While these prices represent the best available estimates, the economic evaluation of a specific project is highly dependent on the producibility of the target zone, the amount of gas in place, the associated geologic and depositional environment, existing pipeline infrastructure, and local tariffs and taxes. 相似文献
999.
1000.
Andrew M. Muir Trent M. Sutton Michael T. Arts Randall M. Claramunt Mark P. Ebener John D. Fitzsimons Timothy B. Johnson Ronald E. Kinnunen Marten A. Koops Maria M. Sepúlveda 《Journal of Great Lakes research》2010
Recent declines in growth and condition of several Great Lakes lake whitefish populations have raised concerns over potential impacts on juvenile physiological condition and ultimately recruitment. To test whether the condition of spawning adults influences juvenile condition via energy allocation dynamics, we partitioned the variation in age 0 juvenile physiological condition (i.e., growth in length and weight, whole-body moisture content, energy density, and protein content) among adult male and female (i.e., body condition, muscle moisture content, energy density, and protein content) and egg (i.e., wet and dry weight, moisture content, energy density, energy content per egg, and protein content) effects using redundancy analysis. Overall, a model that included sampling site, female condition, and egg quality explained 39% of the variation in juvenile physiological condition. After partitioning out the effects of females and eggs, site explained the most variation (23%). When other factors were accounted for, neither females (1.4%) nor eggs (2.7%) explained much variation in juvenile physiological condition. Of the variables studied, female muscle energy density, muscle moisture content, and egg moisture content were most closely associated with juvenile physiological condition. Our results suggest that parental effects, such as size, age, body condition, or body composition, may not be as important as extrinsic site-related effects or density-dependent effects in determining juvenile physiological condition. 相似文献