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91.
Weber Nathan; Brewer Neil; Wells Gary L.; Semmler Carolyn; Keast Amber 《Canadian Metallurgical Quarterly》2004,10(3):139
Data are reported from 3,213 research eyewitnesses confirming that accurate eyewitness identifications from lineups are made faster than are inaccurate identifications. However, consistent with predictions from the recognition and search literatures, the authors did not find support for the "10-12-s rule" in which lineup identifications faster than 10-12 s maximally discriminate between accurate and inaccurate identifications (D. Dunning & S. Perretta, 2002). Instead, the time frame that proved most discriminating was highly variable across experiments, ranging from 5 s to 29 s, and the maximally discriminating time was often unimpressive in its ability to sort accurate from inaccurate identifications. The authors suggest several factors that are likely to moderate the 10-12-s rule. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
92.
93.
Nathan S. Jacobson rew J. Eckel Ajay K. Misra Donald L. Humphrey 《Journal of the American Ceramic Society》1990,73(8):2330-2332
The reactions of a sintered α-SiC with 5% H2 /H2 O/Ar at 1300°C were studied. Thermomchemical modeling indicates that three reaction regions are expected, depending on the initial water vapor or equivalently oxygen content of the gas stream. A high oxygen content ( P (O2 ) > 10−22 atm) leads to a SiO2 formation. This generally forms as a protective film and limits consumption of the SiC (passive oxidation). An intermediate oxygen content (10−22 atm > P (O2 ) > 10−26 atm) leads to SiO and CO formation. These gaseous products can lead to rapid consumption of the SiC (active oxidation). Thermogravimetric studies in this intermediate region gave reaction rates which appear to be controlled by H2 O gas-phase transport to the sample and reacted microstructures showed extensive grain-boundary attack in this region. Finally, a very low oxygen content ( P (O2 ) < 10−26 atm) is thermochemically predicted to lead to selective removal of carbon and formation of free silicon. Experimentally low weight losses and iron silicides are observed in this region. The iron silicides are attributed to reaction of free silicon and iron impurities in the system. 相似文献
94.
Anthropogenic tracers, endocrine disrupting chemicals, and endocrine disruption in Minnesota lakes 总被引:1,自引:0,他引:1
Writer JH Barber LB Brown GK Taylor HE Kiesling RL Ferrey ML Jahns ND Bartell SE Schoenfuss HL 《The Science of the total environment》2010,409(1):100-111
Concentrations of endocrine disrupting chemicals and endocrine disruption in fish were determined in 11 lakes across Minnesota that represent a range of trophic conditions and land uses (urban, agricultural, residential, and forested) and in which wastewater treatment plant discharges were absent. Water, sediment, and passive polar organic integrative samplers (POCIS) were analyzed for steroidal hormones, alkylphenols, bisphenol A, and other organic and inorganic molecular tracers to evaluate potential non-point source inputs into the lakes. Resident fish from the lakes were collected, and caged male fathead minnows were deployed to evaluate endocrine disruption, as indicated by the biological endpoints of plasma vitellogenin and gonadal histology. Endocrine disrupting chemicals, including bisphenol A, 17β-estradiol, estrone, and 4-nonylphenol were detected in 90% of the lakes at part per trillion concentrations. Endocrine disruption was observed in caged fathead minnows and resident fish in 90% of the lakes. The widespread but variable occurrence of anthropogenic chemicals in the lakes and endocrine disruption in fish indicates that potential sources are diverse, not limited to wastewater treatment plant discharges, and not entirely predictable based on trophic status and land use. 相似文献
95.
Morgan A. Wyatt M. C. Y. Mok Prof. Dr. Murray Junop Prof. Dr. Nathan A. Magarvey 《Chembiochem : a European journal of chemical biology》2012,13(16):2408-2415
Through a number of strategies nonribosomal peptide assembly lines give rise to a metabolic diversity not possible by ribosomal synthesis. One distinction within nonribosomal assembly is that products are elaborated on an enzyme‐tethered substrate, and their release is enzyme catalysed. Reductive release by NAD(P)H‐dependent catalysts is one observed nonribosomal termination and release strategy. Here we probed the selectivity of a terminal reductase domain by using a full‐length heterologously expressed nonribosomal peptide synthetase for the dipeptide aureusimine and were able to generate 17 new analogues. Further, we generated an X‐ray structure of aureusimine terminal reductase to gain insight into the structural details associated with this enzymatic domain. 相似文献
96.
Jordan M. Anderson Jigna Patel Ajay S. Karakoti Nathan Greeneltch Diego J. Díaz Sudipta Seal 《Electrochimica acta》2011,56(5):2541
Nanocrystalline Pt/CeO2 composite electrodes were fabricated to study the electrochemical oxidation of methanol and ethanol. The performance of the electrodes was tested as the ceria solutions aged over time. It was observed that the performance oscillated with time, suggesting that the catalytic behavior towards alcohol oxidation was greatly dependent on the aging of the particles. These results point to a great dependence of the catalytic effect on the redox state of the ceria particles. 相似文献
97.
Balayeshwanth R. Vummidi Dr. Jawad Alzeer Prof. Dr. Nathan W. Luedtke 《Chembiochem : a European journal of chemical biology》2013,14(5):540-558
Mounting evidence supports the presence of biologically relevant G‐quadruplexes in single‐cell organisms, but the existence of endogenous G‐quadruplex structures in mammalian cells remains highly controversial. This is due, in part, to the common misconception that DNA and RNA molecules are passive information carriers with relatively little structural or functional complexity. For those working in the field, however, the lack of available tools for characterizing DNA structures in vivo remains a major limitation to addressing fundamental questions about structure–function relationships of nucleic acids. In this review, we present progress towards the direct detection of G‐quadruplex structures by using small molecules and modified oligonucleotides as fluorescent probes. While most development has focused on cell‐permeable probes that selectively bind to G‐quadruplex structures with high affinity, these same probes can induce G‐quadruplex folding, thereby making the native conformation of the DNA or RNA molecule (i.e., in the absence of probe) uncertain. For this reason, modified oligonucleotides and fluorescent base analogues that serve as “internal” fluorescent probes are presented as an orthogonal means for detecting conformational changes, without necessarily perturbing the equilibria between G‐quadruplex, single‐stranded, and duplex DNA. The major challenges and motivation for the development of fluorescent probes for G‐quadruplex structures are presented, along with a summary of the key photophysical, biophysical, and biological properties of reported examples. 相似文献
98.
Susanne V. Hering Nathan M. Kreisberg Mark R. Stolzenburg Gregory S. Lewis 《Aerosol science and technology》2013,47(1):86-96
As part of the California Regional PM 2.5 and PM 10 Air Quality Study (CRPAQS) particle size distributions were measured simultaneously at two sites; the city of Fresno and the agricultural site of Angiola. Reported here are data obtained by scanning mobility analysis over the size range from 10 nm to 400 nm for the intensive study period from December 1, 2000 through February 6, 2001. These high time resolution data show variability in the character of the distributions, as well as the in the total number concentrations. The most pronounced feature of the data set is a consistent, nighttime maxima in particle number concentrations with a modal diameter near 80 nm during the evening hours at the urban Fresno site. Although these maxima are correlated with CO, NO, and black carbon, the particle size is larger than the 30–40 nm modal diameters observed for traffic aerosols during the commute hours, and is attributed to a non-vehicle source. At the agricultural site, the morning maxima particle number concentration coincides with the maxima in NO concentration, but often precedes the morning maxima in black carbon. Values for the geometric mean particle diameter varied from day to day, but are correlated between the two sites, with somewhat larger particle sizes at Angiola during periods of stagnation. 相似文献
99.
Robert J. Osborn Nathan F. Taylor Chance W. Spencer Don R. Collins 《Aerosol science and technology》2013,47(9):759-772
A field-deployable instrument has been developed that isolates from an ambient aerosol those particles that have critical supersaturations, Sc, within a narrow, user-specified, range. This Differential Activation Separator (DAS) consists of two continuous flow diffusion chambers housed within a single enclosure. Particles are introduced into the upstream chamber referred to as the CCN remover (CCNR) near the centerline between a warm, water-soaked, plate and a cool, continuously circulated, water bath. Those particles that activate at the resulting peak supersaturation, Sp, grow quickly and fall into the water bath. The remaining aerosol enters the second chamber referred to as the CCN separator (CCNS), which differs from the CCNR primarily in the use of a salt solution in the lower bath. The imposed temperature differential establishes an Sp slightly higher than that maintained in the upstream chamber, while the presence of a salt solution at the lower boundary results in a subsaturated region in roughly the lower half of the chamber. Those particles having (Sp)CCNR < S c < (Sp)CCNS activate in this chamber and begin to fall due to gravitational settling. Before reaching the lower bath, the droplets evaporate in the subsaturated environment and continue to travel towards the chamber exit. The previously activated particles in the lower half of the chamber and the unactivated particles in the upper half are extracted in separate flows that are subsequently dried. Calibration of the DAS was achieved by measuring the size distribution of separated particles when a polydisperse ammonium sulfate aerosol was introduced. 相似文献
100.