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From DSM-Based Planning to Design Process Simulation: A Review of Process Scheme Logic Verification Issues 总被引:1,自引:0,他引:1
Planning product development processes (PDP), and particularly new product development (NPD) processes, is complex and challenging. The plan should reflect the product-related knowledge, including the influences of performing changes in one product component on the need to rework the design of other components. Given the complexity, dynamics, and uncertainties of design processes (DPs), the plan evaluation requires simulation tools. The design structure matrix (DSM) is a known method for DP planning. However, the DSM itself does not express all the relevant information required for defining process logic. Many logic interpretations are applicable in different business cases; yet, a consistent method of transforming a DSM-based plan to a logically correct concurrent process model in the case of iterative activities is lacking. A gap was identified between the literature concerning activities sequencing based on DSM and the process modeling literature concerning process verification. This survey systematically classifies the approaches used in DSM-based process planning, and discusses their strengths and limitations with problems related to process modeling logic verification of iterative processes. Demonstration of the logic differences emphasizes the need for simulation-based decision making according to the specific process attributes. 相似文献
74.
Sabrina Reich Dr. Hans Wolfgang Hoeffken Dr. Bettina Rosche Dr. Bettina M. Nestl Prof. Dr. Bernhard Hauer 《Chembiochem : a European journal of chemical biology》2012,13(16):2400-2407
The crystal structure of the “ene” nicotinamide‐dependent cyclohexenone reductase (NCR) from Zymomonas mobilis (PDB ID: 4A3U) has been determined in complex with acetate ion, FMN, and nicotinamide, to a resolution of 1.95 Å. To study the activity and enantioselectivity of this enzyme in the bioreduction of activated α,β‐unsaturated alkenes, the rational design methods site‐ and loop‐directed mutagenesis were applied. Based on a multiple sequence alignment of various members of the Old Yellow Enzyme family, eight single‐residue variants were generated and investigated in asymmetric bioreduction. Furthermore, a structural alignment of various ene reductases predicted four surface loop regions that are located near the entrance of the active site. Four NCR loop variants, derived from loop‐swapping experiments with OYE1 from Saccharomyces pastorianus, were analysed for bioreduction. The three enzyme variants, P245Q, D337Y and F314Y, displayed increased activity compared to wild‐type NCR towards the set of substrates tested. The active‐site mutation Y177A demonstrated a clear influence on the enantioselectivity. The loop‐swapping variants retained reduction efficiency, but demonstrated decreased enzyme activity compared with the wild‐type NCR ene reductase enzyme. 相似文献
75.
<正>中学和大学的学生们不会有很多人把印刷传播行业作为自己的职业生涯,这也是我们行业的一个大问题。因此,面临的挑战是如何激发学生,让其考虑将印刷传播行 相似文献
76.
Meharg AA Pain DJ Ellam RM Baos R Olive V Joyson A Powell N Green AJ Hiraldo F 《The Science of the total environment》2002,300(1-3):81-86
White storks (Ciconia ciconia) fed in contaminated waters resulting from the Aznacollar acid mining-sludge spillage into the R. Guadiamar, which feeds the eastern flank of the Guadalquivir marshes (Do?ana), S.W. Spain. The sludge was rich in a range of toxic elements, and in organic pollutants such as the aromatic amines. Storks did not exhibit elevated metals in their blood immediately following the accident, but chick blood collected the year following the accident showed genotoxic damage compared to the controls. In this study lead isotope analysis was used to assess if the storks had ingested sludge-derived contaminants. The sludge lead isotope ratio was distinct from that of the Do?ana sediments. The stork blood lead isotope ratios exactly matched that of the sludge. It was concluded that the storks had ingested sludge-derived contaminants. A detailed study of the lead contamination along the R. Guadiamar and the R. Guadalquivir (of which the Guadiamar is a tributary) was also conducted to place the white stork colony lead exposure in the context of the spatial contamination of the storks' habitat. 相似文献
77.
Ridgwell AJ 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2002,360(1801):2905-2924
Understanding the response of the Earth's climate system to anthropogenic perturbation has been a pressing priority for society since the late 1980s. However, recent years have seen a major paradigm shift in how such an understanding can be reached. Climate change demands analysis within an integrated 'Earth-system' framework, taken to encompass the suite of interacting physical, chemical, biological and human processes that, in transporting and transforming materials and energy, jointly determine the conditions for life on the whole planet. This is a highly complex system, characterized by multiple nonlinear responses and thresholds, with linkages often between apparently disparate components. The interconnected nature of the Earth system is wonderfully illustrated by the diverse roles played by atmospheric transport of mineral 'dust', particularly in its capacity as a key pathway for the delivery of nutrients essential to plant growth, not only on land, but perhaps more importantly, in the ocean. Dust therefore biogeochemically links land, air and sea. This paper reviews the biogeochemical role of mineral dust in the Earth system and its interaction with climate, and, in particular, the potential importance of both past and possible future changes in aeolian delivery of the micro-nutrient iron to the ocean. For instance, if, in the future, there was to be a widespread stabilization of soils for the purpose of carbon sequestration on land, a reduction in aeolian iron supply to the open ocean would occur. The resultant weakening of the oceanic carbon sink could potentially offset much of the carbon sequestered on land. In contrast, during glacial times, enhanced dust supply to the ocean could have 'fertilized' the biota and driven atmospheric CO(2) lower. Dust might even play an active role in driving climatic change; since changes in dust supply may affect climate, and changes in climate, in turn, influence dust, a 'feedback loop' is formed. Possible feedback mechanisms are identified, recognition of whose operation could be crucial to our understanding of major climatic transitions over the past few million years. 相似文献
78.
We focus on the fabrication and study of controllable holographic gratings based on azo-dye-doped and undoped polymer-ball-type polymer-dispersed liquid-crystal films. Experimental results indicate that the next step of photopolymerization of the sample with the illumination of Ar+ laser beams after UV curing causes a latent density grating to be recorded. This grating is formed by a selective secondary photopolymerization. Heating and applying a voltage change the structure of the liquid crystal and induce the appearance of the latent grating. Diffraction efficiencies versus temperature, voltage, and state of polarization are studied for both dye-doped and undoped cells and are found to be quite different. This discrepancy is attributable to the reorientation effect of liquid crystals through their interaction with the photo-induced adsorption of the doped dyes on the surface of polymer balls in the dye-doped cell. 相似文献
79.
Erratum
Biomimetic Representation with Enzyme Genetic Programming 相似文献80.