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31.
In this study the authors examine the effects of procedures adapted from the cognitive interview of R. E. Geiselman, R.P. Fisher, D.P. MacKinnon, and H.L. Holland (1985) on children's recall following exposure to misleading suggestions. Children aged 5-7 years and 9-11 years saw a videotaped story and were presented with misleading or neutral information concerning story details. All were later given free- and cued-recall tests preceded by standard interview instructions or instructions that reinstated the encoding context and encouraged exhaustive reporting. Increased recall accuracy was found following cognitive interview instructions. Both age groups were susceptible to misleading suggestions, but susceptibility was unaffected by interview type. The authors discuss the implications for interviewing child witnesses.  相似文献   
32.
This study was undertaken to determine the effect of various lipid emulsions on the hepato-biliary system in rats. Rats were randomly divided into six groups and infused continuously for 48 hr with either long-chain triglycerides (LCT), medium-chain triglycerides (MCT) or a mixture of MCT and LCT. One group infused with physiological saline solution served as controls. Throughout this period the rats received a fat free dietad libitum. During the last hour of lipid infusion bile was collected for determination of bile flow and composition. Subsequently, the rats were sacrificed and the morphology and lipid content of the liver determined. Only LCT lipid emulsions induced morphological changes and increased liver cholesterol content. In two rats infused with radiolabeled LCT, no labeled cholesterol was found in the liver, indicating that the excess hepatic cholesterol level may originate from enhanced cholesterol mobilization to the liver. Biliary cholesterol and phospholipid concentrations in LCT-treated rats were also elevated, as was the lithogenic index, whereas the other emulsions had no such effects. None of the emulsions affected the plasma liver function tests or bile flow. We therefore conclude that the lithogenicity of the bile in rats is directly related to the lipid components of the total parenteral nutrition and the type of triglyceride infused.  相似文献   
33.
Robe.  BK Elli.  BD 《绿箭信息》2000,1(11):10-11,32
介绍了在液相中连续生产1,1,1,3,3,3,-六氟丙烷(HFC236fa)和/或1-氯-1,1,3,3,3-五氟内烷(HCFC235fa)的工艺,反应中使用HCFC-235fa和/或HFC236fa作为溶剂。当反应是在SbF3、SbF5或SbF5和HSO3F的混合物催化剂存在下进行时,反应物料对所用容器的腐蚀非常低。  相似文献   
34.
Governments worldwide should provide incentives for initial large-scale GS projects to help build the knowledge base for a mature, internationally harmonized GS regulatory framework. Health, safety, and environmental risks of these early projects can be managed through modifications of existing regulations in the EU, Australia, Canada, and the U.S. An institutional mechanism, such as the proposed Federal Carbon Sequestration Commission in the U.S., should gather data from these early projects and combine them with factors such as GS industrial organization and climate regime requirements to create an efficient and adaptive regulatory framework suited to large-scale deployment. Mechanisms to structure long-term liability and fund long-term postclosure care must be developed, most likely at the national level, to equitably balance the risks and benefits of this important climate change mitigation technology. We need to do this right. During the initial field experiences, a single major accident, resulting from inadequate regulatory oversight, anywhere in the world, could seriously endanger the future viability of GS. That, in turn, could make it next to impossible to achieve the needed dramatic global reductions in CO2 emissions over the next several decades. We also need to do it quickly. Emissions are going up, the climate is changing, and impacts are growing. The need for safe and effective CO2 capture with deep GS is urgent.  相似文献   
35.
The theoretical framework developed in this study allows development of a model of deregulated electricity markets that explains two familiar empirical findings; the existence of forward premiums and price-cost markups in the spot market. This is a significant contribution because electricity forward premiums have been previously explained exclusively by the assumptions of perfect competition and risk-averse behavior while spot markups are generally the outcome of a body of literature assuming oligopolistic competition. Our theoretical framework indicates that a certain premium for forward contracting is required for efficient allocation of generation capacity. However, due to the uniqueness of electricity and the design of deregulated electricity markets this premium might be substantially higher than its optimal level.  相似文献   
36.
The Enhanced Traffic Management System (ETMS) is a legacy system used by the Federal Aviation Administration (FAA) to support air traffic flow management. Air traffic flow management is the strategic control of air traffic to minimize delays and congestion and maximize the throughput of aircraft throughout the National Airspace System (NAS). This paper discusses the reasons for modeling a legacy system, problems and advantages encountered in modeling an operational system, and describes the construction of a simulation model of ETMS. Originally written in Pascal to run on Apollo workstations under the Aegis Domain operating system, ETMS has been converted to C/C++ and ported to HP servers and workstations running HP-UX, a POSIX-compliant version of UNIX. The objectives of the modeling task were to assess performance of the ported system and to provide a basis for evaluating a possible redesign/re-architecture of the system. The initial plan was to develop one or two models aimed at the network aspects (both LAN and WAN) of ETMS at a relatively high level, and then to develop a more detailed model to look at specific workstation/server issues.As is shown in this paper, issues of existing system design and documentation and the availability (or the lack) of data continually arose. Nevertheless, a reasonable set of working assumptions were derived which allowed modeling and evaluation to proceed. Thus, the quantitative and qualitative results obtained provided information and lessons learned that can be built upon. Moreover, the second of the stated goals (to provide a basis for possible redesign) was also achieved because there is now a baseline for future design/architecture studies. The focus of this paper is to provide insights into the issues involved in modeling an existing system rather than the results of the model itself.  相似文献   
37.
We study the delay performance of all-optical packet communication networks configured as ring and bus topologies employing cross-connect switches (or wavelength routers). Under a cross-connect network implementation, a packet experiences no (or minimal) internal queueing delays. Thus, the network can be implemented by high speed all-optical components. We further assume a packet-switched network operation, such as that using a slotted ring or bus access methods. In this case, a packet's delay is known before it is fed into the network. This can be used to determine if a packet must be dropped (when its end-to-end delay requirement is not met) at the time it accesses the network. It also leads to better utilization of network capacity resources. We also derive the delay performance for networks under a store-and-forward network operation. We show these implementations to yield very close average end-to-end packet queueing delay performance. We note that a cross-connect network operation can yield a somewhat higher queueing delay variance levels. However, the mean queueing delay for all traffic flows are the same for a cross-connect network operation (under equal nodal traffic loading), while that in a store-and-forward network increases as the path length increases. For a ring network loaded by a uniform traffic matrix, the queueing delay incurred by 90% of the packets in a cross-connect network may be lower than that experienced in a store-and-forward network. We also study a store-and-forward network operation under a nodal round robin (fair queueing) scheduling policy. We show the variance performance of the packet queueing delay for such a network to be close to that exhibited by a cross-connect (all-optical) network.  相似文献   
38.
Previous theories which evaluated the stagnation depth of bubbles in a vertically oscillating liquid column are reviewed, and it is pointed out that they used an insufficient criterion for determining stagnation. The correct condition, which states that stagnation means zero mean velocity rather than acceleration, necessitates the solution of the equation of motion of the bubble, and thus viscous drag has to be included. It is shown, in accordance with available experimental data, that the value of the dimensionless group M = ω4A2ρh/2gPo (which gives the stagnation depth h) is not in general a constant, but is dependent on four other dimensionless groups. Although there is no reliable information concerning the drag coefficient curve for such a situation, it is suggested, on the basis of comparison between different drag coefficient curves, that the high values of M reported in the literature and not accounted for by theory are due to bubble shape deviations from sphericity in viscous flow.  相似文献   
39.
Canola oil was hydrogenated using a mixture of homogeneous methyl benzoate-Cr(CO)3 and heterogeneous nickel catalysts. The effect of the methyl benzoate-Cr(CO)3_to-nickel ratio on the activity, specific isomerization index, linoleate and linolenate selectivities, and fatty acid composition was evaluated, and the results compared with those obtained with commercial nickel catalyst and methyl benzoate-Cr(CO)3 used individually. At higher chromium-to-nickel ratios the activity of nickel was inhibited and the system behaved essentially like the pure chrome complex, while at low chromium-to-nickel ratios the characteristics of the nickel predominated. In a short transition zone relatively high reaction rates were obtained with significantly reducedtrans-isomer levels in the product. In a broader sense, it may be possible to combine a homogeneous and heterogeneous catalyst while retaining the advantages of both. We may thus be able to design catalyst systems for specific applications.  相似文献   
40.
The authors compare student's achievement in tests with low and moderately high number of questions requiring short answers. Five groups of Medical School students underwent their regular Anatomy evaluation tests, which consisted of 13 questions (one group), 15 (two groups) and 25 (two groups). In each group five questions were chosen at random, average scores being calculated from their marks. These scores were statistically compared to the ones calculated from the marks given to the full-length evaluation tests; it became quite evidente that averages go up when the number of questions is increased. Putting the averages in terms of A, B, C and D scores (very good, good, regular and insufficient), it was noted that failure to reach at least the C score is inversely proportional to the number of questions. The results are discussed in terms of determining the most proper number of questions to be given in a test.  相似文献   
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