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41.
Network Denial-of-Service (DoS) attacks that disable network services by flooding them with spurious packets are on the rise. Criminals with large networks (botnets) of compromised nodes (zombies) use the threat of DoS attacks to extort legitimate companies. To fight these threats and ensure network reliability, early detection of these attacks is critical. Many methods have been developed with limited success to date. This paper presents an approach that identifies change points in the time series of network packet arrival rates. The proposed process has two stages: (i) statistical analysis that finds the rate of increase of network traffic, and (ii) wavelet analysis of the network statistics that quickly detects the sudden increases in packet arrival rates characteristic of botnet attacks.Most intrusion detections are tested using data sets from special security testing configurations, which leads to unacceptable false positive rates being found when they are used in the real world. We test our approach using data from both network simulations and a large operational network. The true and false positive detection rates are determined for both data sets, and receiver operating curves use these rates to find optimal parameters for our approach. Evaluation using operational data proves the effectiveness of our approach. 相似文献
42.
Milk production of dairy cows fed differing concentrations of rumen-degraded protein 总被引:1,自引:0,他引:1
Thirty-two multiparous and 16 primiparous Holstein cows in midlactation averaging 126 d in milk were used to determine the effects of rumen-degraded protein (RDP) concentration on lactation performance. Cows were assigned to diets in a repeated Latin square design with 3-wk experimental periods. Diets were formulated to provide 4 concentrations of dietary RDP [6.8, 8.2, 9.6, and 11.0% of dry matter (DM)] while rumen-undegraded protein remained constant (5.8% of DM). Diets contained 50% corn silage and 50% concentrate (DM basis). Ingredients within diets were equal across treatments except for ground corn, soybean meal, and ruminally protected soybean meal. Dry matter intake was not affected by treatment. Milk yield, fat yield, and protein yield all increased linearly when cows were fed diets with greater RDP. Milk fat and protein concentration each increased by 0.16 percentage units for cows fed 11% RDP compared with 6.8% RDP. Milk protein yield increased by 0.19 g/d for every 1 g/d increase in crude protein supplied mainly as RDP. As RDP increased, the efficiency of N use declined linearly. Milk urea N increased linearly when cows were fed increasing amounts of RDP, indicating increased losses of N via urine. Feeding deficient RDP diets to dairy cows can decrease nitrogen excretion, but it also decreases lactation performance. These data show an environmental benefit from underfeeding RDP to dairy cows according to National Research Council requirements, but at a financial cost to the dairy producer. 相似文献
43.
Chemical characterization of the mutagenic neutral aromatic polar fractions of petroleum substitutes
The constituents of the neutral aromatic polar subfractions of two coal-derived oils, a shale-derived oil and a petroleum oil were analysed and compared. Chemical ionization mass spectra, using methanol and ammonia as reagent gases, were used to characterize the oxygen-and nitrogen-containing constituents, respectively. The compositions of the petroleum substitutes were found to differ from those of petroleum in containing primary polycyclic aromatic amines, azaarenes, polycyclic hydroxyaromatics and, in one case, aromatic ketones. 相似文献
44.
The purpose of the ozone process at the Sebago Lake Water Treatment Facility (SLWTF) is to meet the disinfection requirements of the Surface Water Treatment Rule with ozone and without filtration. The start-up experience is presented including initial operating strategies to meet disinfection requirements. An ozone system performance test conducted during the first month of plant operation is described and the results are reviewed. The initial and proposed activities of an ozone optimization project are discussed. 相似文献
45.
Steroidal glycoalkaloids, found in species of the Solanaceae, elicit bursting activity in galeal and tarsal chemosensilla of adult Colorado potato beetles. The effect has an average latency of 6–12 sec, depending on the sensillum/alkaloid combination. A 20-sec alkaloid treatment is often suffficient to render galeal sensilla unresponsive to gamma-aminobutyric acid, normally an effective stimulant. The alkaloids have similar effects on galeal sensilla of larval Colorado potato beetles and on labellar chemosensilla of the blowfly. It is concluded that these compounds act independently of any specialized chemoreceptor in the Colorado potato beetle, and that association of the Colorado potato beetle with solanaceous plants has not led to evolution of a specific receptor forSolanum glycoalkaloids. 相似文献
46.
Angela Siner Weiling Xue Glenn Talaska David Warshawsky Deborah L. Gray Ronald Nines 《Polycyclic Aromatic Compounds》2013,33(3-4):893-897
Complex mixtures consist of homocyclic and heterocyclic polycyclic aromatic compounds (PACs) represented by benzo[ a ]pyrene (B a P) and 7 H -dibenzo[ c,g ]carbazole (DBC), respectively. To exert their biological effects, PACs are metabolized into reactive intermediates, which can form DNA adducts. In this preliminary report, male A/J mice were given a single intraperitoneal injection. Groups of three animals were treated with DBC (2 or 10 mg/kg) or B a P (10 or 100 mg/kg). Mixtures of DBC:B a P were given at doses of 2:10, 2:100, 10:10, or 10:100 mg/kg. DNA adduct levels in lungs collected three days posttreatment were determined by the 32 P-postlabeling method. The results indicate that, in the lungs, exposure to mixtures containing more B a P than DBC resulted in the absence of adduct 3 (DBC) and significantly higher total adduct levels. This suggests that B a P is being preferentially metabolized, resulting in less DBC adduction. 相似文献
47.
Syed H. Imam Cristina Bilbao-Sainz Bor-Sen Chiou Gregory M. Glenn William J. Orts 《Journal of Adhesion Science and Technology》2013,27(18-19):1972-1997
Biopolymers derived from renewable resources are an emerging class of advanced materials that offer many useful properties for a wide range of food and nonfood applications. Current state of the art in research and development of renewable polymers as adhesives, gums, binders, and emulsions is the subject of this review. Much of the focus will be on major biopolymers such as starch, proteins, lignin, oils, and their derivatives found in both natural and modified forms, but other biopolymers of promising commercial interest will also be included where warranted. Polymers produced in nature are remarkably diverse in their chemistry, thermomechanical properties, rheology, plasticity, and chemical reactivity. In particular, their capacity to undergo a wide array of chemical modifications yields materials with tailored properties suitable for use as adhesives, gums, coatings, emulsions, and binders. Many such materials are now widely used in commercial products like building materials, lubricants, sealants, coatings, bonding aids, pharmaceuticals, paper, glues, flocculants, processed and frozen foods, as well as tissue engineering and bone repair products. This review provides a general overview of biobased polymers highlighting their source, availability, properties, and usage in industrial products along with the future prospects, challenges, and opportunities they offer. 相似文献
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