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排序方式: 共有895条查询结果,搜索用时 15 毫秒
881.
Yasmine Mendes Pupo Paulo Vitor Farago Milton Domingos Michél Jessica Mendes Nadal Luis Antônio Esmerino Carlos Mauricio Lepienski 《The Journal of Adhesion》2015,91(5):356-368
The objective of this study was to assess the in vitro effect of a quaternary ammonium methacrylate polymer (QAMP) incorporated into a self-etching adhesive system on inhibiting caries by evaluating the mechanical properties of the adhesive interface. Twenty-four human third molars were distributed into: Clearfil? SE Bond containing 5% QAMP (experimental group), Clearfil? Protect Bond (positive control), and Clearfil? SE Bond (negative control). Teeth of each group were divided according to the method for producing artificial caries lesions: pH-cycling or microbiological assay. All samples were sectioned and polished in order to obtain hardness (H) and Young's modulus (E) values by nanoindentation test in the hybrid layer and dentin. Data were analyzed by ANOVA and Games Howell's post hoc test (α = 0.05). Regarding the hybrid layer, Clearfil? SE Bond containing QAMP demonstrated H and E values statistically higher than Clearfil? SE Bond in both pH-cycling and microbiological experiments. Considering dentin, Clearfil? SE Bond containing QAMP showed H and E values statistically higher than Clearfil? Protect Bond and Clearfil? SE Bond in the pH-cycling method and then Clearfil? SE Bond concerning the microbiological method. In general, Clearfil? SE Bond containing QAMP provided better mechanical properties for the resin–dentin interface after cariogenic challenges. 相似文献
882.
Cooperating CoScheduling: A Coscheduling Proposal Aimed at Non-Dedicated Heterogeneous NOWs 下载免费PDF全文
Implicit coscheduling techniques applied to non-dedicated homogeneous Networks Of Workstations (NOWs) have shown they can perform well when many local users compete with a single parallel job. Implicit coscheduling deals with minimizing the communication waiting time of parallel processes by identifying the processes in need of coscheduling through gathering and analyzing implicit runtime information, basically communication events. Unfortunately, implicit coscheduling techniques do not guarantee the performance of local and parallel jobs, when the number of parallel jobs competing against each other is increased. Thus, a low efficiency use of the idle computational resources is achieved.
In order to solve these problems, a new technique, named Cooperating CoScheduling (CCS), is presented in this work. Unlike traditional implicit coscheduling techniques, under CCS, each node takes its scheduling decisions from the occurrence of local events, basically communication, memory, Input/Output and CPU, together with foreign events received from cooperating nodes. This allows CCS to provide a social contract based on reserving a percentage of CPU and memory resources to ensure the progress of parallel jobs without disturbing the local users, while coscheduling of communicating tasks is ensured. Besides, the CCS algorithm uses status information from the cooperating nodes to balance the resources across the cluster when necessary. Experimental results in a non-dedicated heterogeneous NOW reveal that CCS allows the idle resources to be exploited efficiently, thus obtaining a satisfactory speedup and provoking an overhead that is imperceptible to the local user. 相似文献
In order to solve these problems, a new technique, named Cooperating CoScheduling (CCS), is presented in this work. Unlike traditional implicit coscheduling techniques, under CCS, each node takes its scheduling decisions from the occurrence of local events, basically communication, memory, Input/Output and CPU, together with foreign events received from cooperating nodes. This allows CCS to provide a social contract based on reserving a percentage of CPU and memory resources to ensure the progress of parallel jobs without disturbing the local users, while coscheduling of communicating tasks is ensured. Besides, the CCS algorithm uses status information from the cooperating nodes to balance the resources across the cluster when necessary. Experimental results in a non-dedicated heterogeneous NOW reveal that CCS allows the idle resources to be exploited efficiently, thus obtaining a satisfactory speedup and provoking an overhead that is imperceptible to the local user. 相似文献
883.
Oscar Valdés Fabián Ávila‐Salas Adolfo Marican Natalia Fuentealba Jorge Villaseñor Mauricio Arenas‐Salinas Yerko Argandoña Esteban F. Durán‐Lara 《应用聚合物科学杂志》2018,135(11)
This study describes the absorption of methamidophos (MMP) from aqueous solution by crosslinked poly(vinyl alcohol) (PVA) hydrogel synthesized using malic acid (MA) as a crosslinker (CLPHMA). The prepared hydrogels were characterized by FTIR spectroscopy, scanning electron microscopy, and the thermal properties were studied by using thermal gravimetric analysis. Also, the swelling index as a function of PVA:MA composition and pH were studied. An in silico rational study, which involved all‐atom molecular dynamics simulations of PVA:MA systems in proportions 10:2, 10:4, and 10:6 was performed. The in silico studies concluded that the more suitable crosslinking degree for MMP pesticide removal is with the 20% (wt %) of crosslinker (CLPHMA‐20). The experimental analysis of MMP removal with CLPHMA was performed as well. It was found that the prepared CLPHMA‐20 had a great efficiency to recover around 86% of MMP from their solutions. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45964. 相似文献
884.
885.
Haoyue Zhu Cuicui Wang Jun Zhou Mimi Wan Ying Wang Zhigang Zou Mauricio Terrones 《Journal of Porous Materials》2018,25(6):1659-1668
Aimed to prepare high efficient dye sorbent and control water pollution, herein we utilized solvothermal method to synthesize porous polyimide (PI) polymer with a large surface area using DMSO as solvent. Unlike the solid-state thermal polymerized PI with low surface area of 5 m2g?1, this PI material prepared in DMSO solvent possessed a large surface area of 430 m2g?1, which was beneficial for adsorption of organic dye in waste water, achieving a max MO adsorption of 200 mg g?1 three times higher than that of multiwalled carbon nanotube. The adsorption kinetics of dye molecules on PI was investigated in detail and the R2 value of 0.99071 for pseudo-second-order model confirms the adsorption was fitted best with Langmuir isotherm. 相似文献
886.
Zimmer KE Montaño M Olsaker I Dahl E Berg V Karlsson C Murk AJ Skaare JU Ropstad E Verhaegen S 《The Science of the total environment》2011,409(11):2040-2048
This study investigated the effects of two mixtures of persistent organic pollutants (POPs) on steroidogenesis in the H295R cell line. The two mixtures were obtained from the livers of burbot (Lota lota) caught in two Norwegian lakes (Mjøsa and Losna) with different contaminant profiles. Steroid hormone levels in the cell culture medium and mRNA levels of 16 genes involved in steroidogenesis were investigated. The crude Lake Mjøsa extract had to be diluted ten times more than the Lake Losna extract in order to prevent cytotoxicity. The ten times diluted Lake Mjøsa mixture had higher levels of DDT and derivates (∑ DDTs, 1.7 times) and brominated flame retardants (∑ BDEs and HBCD, 15-25 times) than the Lake Losna mixture, which, on the other hand, had higher concentrations of ∑ PCBs (1.5 times higher) and also of HCB, ∑ HCH isomers and ∑ chlordane isomers (5-20 times higher).In the cell culture media, only cortisol levels were increased at the highest exposure concentration to the Lake Mjøsa mixture, while both cortisol and estradiol levels were increased following exposure to the two highest Lake Losna mixture exposure concentrations. Testosterone levels decreased only at the highest exposure concentration of the Lake Losna mixture. Multivariate models suggested that ∑ PCBs, and to a lesser extent ∑ DDTs, were responsible for the cortisol responses, while estradiol and testosterone alterations were best explained by HCB and ∑ PCBs, respectively. Exposure to the mixtures generally increased mRNA levels, with smaller effects exerted by the Lake Mjøsa mixture than the Lake Losna mixture. It was concluded that both mixtures affected steroidogenesis in the H295R cells. Small differences in mixture composition, rather than the high content of brominated flame retardants in the Lake Mjøsa mixture, were suggested to be the most probable reason for the apparent differences in potencies of the two mixtures. 相似文献
887.
Over 90 percent of companies are estimated to use IT Service Management (ITSM) frameworks, yet there is little research on their benefits to the Information Technology (IT) department and the business units. An international survey of 491 firms was conducted to assess the benefits of the IT Infrastructure Library (ITIL), the de-facto ITSM framework, specifically on how these benefits evolve as companies increase their adoption of the ITIL model. Also studied are the perception of challenges of the implementation and the number of ITIL processes implemented in relation to the progress of the adoption of ITIL. Results indicate that as the maturity of implementation increases, the perception of challenges decreases. Findings also show that as the maturity of implementation increases, the number of realized benefits increases, as well as the number of implemented ITIL processes. Implications for practitioners and researchers are also discussed. 相似文献
888.
Mauricio CL da Silva HL da Silva CR Bittencourt RV Souza-Santos D 《Radiation protection dosimetry》2011,144(1-4):115-118
Brazil, a large country, with more than 120,000 workers under individual monitoring for ionising radiation, developed, more than 20 y ago, a centralised data bank for external occupational dose. This old database, however, presented some problems and does not satisfy any more Brazilian present needs, not allowing dose analysis reports, for example. Therefore, a new system that reduces manual tasks, provides system communication support, manages reports and improves data storage management is being developed. This paper describes this new web-based information system, named Brazilian External Occupational Dose Management database system--GDOSE. 相似文献
889.
Chang PK Abbas HK Weaver MA Ehrlich KC Scharfenstein LL Cotty PJ 《International journal of food microbiology》2012,154(3):192-196
Contamination of corn, cotton, peanuts and tree nuts by aflatoxins is a severe economic burden for growers. A current biocontrol strategy is to use non-aflatoxigenic Aspergillus flavus strains to competitively exclude field toxigenic Aspergillus species. A. flavus K49 does not produce aflatoxins and cyclopiazonic acid (CPA) and is currently being tested in corn-growing fields in Mississippi. We found that its lack of production of aflatoxins and CPA resulted from single nucleotide mutations in the polyketide synthase gene and hybrid polyketide-nonribosomal peptide synthase gene, respectively. Furthermore, based on single nucleotide polymorphisms of the aflatoxin biosynthesis omtA gene and the CPA biosynthesis dmaT gene, we conclude that K49, AF36 and previously characterized TX9-8 form a biocontrol group. These isolates appear to be derived from recombinants of typical large and small sclerotial morphotype strains. This finding provides an easy way to select future biocontrol strains from the reservoir of non-aflatoxigenic populations in agricultural fields. 相似文献
890.
Andréia Cristina FurtadoChristian Gonçalves Alonso Mauricio Pereira CantãoNádia Regina Camargo Fernandes-Machado 《International Journal of Hydrogen Energy》2011,36(16):9653-9662
The ethanol oxidative reforming reaction was performed with Ni-Cu catalysts on different supports. The results indicated that Ni-Cu/Nb2O5 and Ni-Cu/ZnO were the most appropriate catalysts for the reaction regarding activity, stability, and selectivity for hydrogen production. Ni-Cu/Nb2O5 catalysts have strong acidity (at 600 °C), while ZnO has very low acidity. Ni-Cu/Ce0.6Zr0.4O2 catalysts, which only have weak acidity (at 250 °C), presented poor stability and hydrogen selectivity. This shows that acidity has no influence on hydrogen production. 相似文献