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101.
In order to determine changes in breathing patterns brought about by resistive loading, ventilation was recorded in 11 healthy subjects with four linear resistances (3.57, 5.75, 8.76 and 13.13 cmH2O L(-1) sec) added in a random order throughout the entire breath. At steady state, a breath-by-breath analysis of airflow was used to quantify the pattern of breathing in terms of respiratory variables: TI, TE, Tt, VT, VT/TI, TI/Tt, and by taking TI, TE, VT all together (TRIAD) and also the shape of the entire airflow profile quantified by harmonic analysis (ASTER). Group analysis using ANOVA showed significant changes in all variables. There were increasing changes with increasing loads in all variables, the smallest changes being in TI/Tt. Within to between-individual comparisons between two loads showed that only TI/Tt and the ASTER were more similar within than between-individuals for all comparisons. It was concluded that at steady state mechanisms of load compensation come into play inducing changes in the pattern of breathing proportional to the loads while maintaining some of the individual characteristics. 相似文献
102.
103.
Deinococcus radiodurans R1 and other members of this genus share extraordinary resistance to the lethal and mutagenic effects of ionizing radiation. We have recently identified a RecA homolog in strain R1 and have shown that mutation of the corresponding gene causes marked radiosensitivity. We show here that following high-level exposure to gamma irradiation (1.75 megarads, the dose required to yield 37% of CFU for plateau-phase wild-type R1), the wild-type strain repairs > 150 double-strand breaks per chromosome, whereas a recA-defective mutant (rec30) repairs very few or none. A heterologous Escherichia coli-D. radiodurans shuttle plasmid (pMD68) was constructed and found to be retained in surviving D. radiodurans R1 and rec30 following any radiation exposure up to the highest dose tested, 3 megarads. Plasmid repair was monitored in vivo following irradiation with 1.75 megarads in both R1/pMD68 and rec30/pMD68. Immediately after irradiation, plasmids from both strains contained numerous breaks and failed to transform E. coli. While irradiation with 1.75 megarads was lethal to rec30 cultures, a small amount of supercoiled plasmid was regenerated, but it lacked the ability to transform E. coli. In contrast, wild-type cultures showed a cell division arrest of about 10 h, followed by exponential growth. Supercoiled plasmid was regenerated at normal levels, and it readily transformed E. coli. These studies show that D. radiodurans retains a heterologous plasmid following irradiation and repairs it with the same high efficiency as its chromosomal DNA, while the repair defect in rec30 prevents repair of the plasmid. Taken together, the results of this study suggest that plasmid DNA damaged in vivo in D. radiodurans is repaired by recA-dependent mechanisms similar to those employed in the repair of chromosomal DNA. 相似文献
104.
TF Davenport JR Albright JH Goldman SL Hagopian JE Lannutti KW Lai J LeBritton YC Lin AE Pifer HC Fenker DR Green GE Canough CC Chang TC Davis RW Joyner JA Poirier CH Georgiopoulos A Napier JM Marraffino JW Waters MS Webster EG Williams J Woosley JR Ficenec S Torres WP Trower 《Canadian Metallurgical Quarterly》1986,33(9):2519-2527
105.
PS Jensen KW Grace R Attariwala JE Colgate MR Glucksberg 《Canadian Metallurgical Quarterly》1997,235(11):696-701
BACKGROUND: Experimental protocol in our laboratory routinely requires the precise placement of instruments at, or near, the retina. Although manipulators for placing an instrument within the eye presently exist, none of the designs were satisfactory due to limitations on size, accuracy and operability. To overcome these limitations, we have developed a novel six degree of freedom manipulator designed specifically for retinal microsurgery. METHODS: The manipulator is parallel in structure and provides submicrometer positioning of an instrument within the constrained environment of the eye. The position of an instrument attached to the manipulator is commanded by the operator using a hand-held trackball. A computer controller interprets the trackball input and moves the manipulator in an intuitive manner according to mathematically constrained modes of operation. RESULTS: Over 50 retinal vessels in the live, anesthetized cat have been successfully cannulated for pressure measurement and drug injection using the described manipulator and micropuncture techniques. The targeted vessels ranged in internal diameter from 20 to 130 microns. CONCLUSION: This device has applications in microsurgery where tremor and fatigue limit the performance of an unaided hand and where mechanically constrained manipulators are inappropriate due to size and operative constraints. 相似文献
106.
107.
LJ Sokoll SL Booth ME O'Brien KW Davidson KI Tsaioun JA Sadowski 《Canadian Metallurgical Quarterly》1997,65(3):779-784
The response of osteocalcin and other biochemical markers of vitamin K status to diets formulated to contain different amounts of phylloquinone was assessed in nine healthy subjects aged 20-33 y. Subjects resided in a metabolic ward for two 15-d cycles with a minimum of 6 wk between cycles. A mixed diet containing 100 micrograms phylloquinone/d was fed throughout both cycles; however, the phylloquinone content of one of the cycles was increased to a total of 420 micrograms/d on days 6 through 10 by fortifying corn oil in the diet with phylloquinone (supplemented diet). Total serum osteocalcin concentrations were not affected by either of the dietary treatments. The percentage of undercarboxylated osteocalcin increased an average of 28% over the 15-d cycle with the mixed diet (P < 0.05) and declined significantly an average of 41% with 5 d of the supplemented diet (day 6: 21.9 +/- 1.3%, day 11: 12.8 +/- 1.1%; P = 0.0001) with a rise after the return to the mixed diet (16.7 +/- 1.3%, P < 0.001). Plasma phylloquinone concentrations increased significantly with supplementation (day 6: 0.95 +/- 0.16 nmol/L, day 11: 1.40 +/- 0.29 nmol/L; P < 0.001) and then rapidly returned to presupplementation concentrations on returning to the mixed diet. Twenty-four-hour ratios of urinary gamma-carboxyglutamic acid to creatinine were unchanged with the supplemented diet; however, excretion declined to 91 +/- 2% of baseline after 10 d on the mixed diet (P = 0.01). These results show that undercarboxylated osteocalcin, plasma phylloquinone, and urinary gamma-carboxyglutamic acid excretion appear to be sensitive measures of vitamin K nutritional status because all of these variables were responsive to changes in dietary intake. 相似文献
108.
131I dose-dependent thyroid autoimmune disorders in children living around Chernobyl 总被引:1,自引:0,他引:1
EV Vykhovanets VP Chernyshov II Slukvin YG Antipkin AN Vasyuk HF Klimenko KW Strauss 《Canadian Metallurgical Quarterly》1997,84(3):251-259
The nucleotide sequence of 35,400 bp at approximately 10 kb from the right telomere of chromosome VII was determined. The segment contains the MAL1 locus, one of the five unlinked loci sufficient for maltose utilization. Until now, each of these loci was considered to contain three genes (for regulator, permease and alpha-glucosidase), but a fourth gene, presumably an extra alpha-glucosidase gene, was found at MAL1 adjacent to the usual cluster of three genes. The two glucosidase genes are present in opposite orientation, forming an inverted repeat structure. In addition to the four genes at MAL1, there are 11 complete, non-overlapping open reading frames (ORFs) longer than 300 bp in the sequence presented here. A new ABC transporter gene (YGR281w), required for oligomycin resistance was found (YOR1; Katzman et al., 1995), and the previously sequenced BGL2 (YGR282c), ZUO1 (YGR285c) and BIO2 (YGR286c) genes were located. The sequence of BIO2, a biotin synthetase gene, required substantial correction and the size of Bio2p is 375, rather than 356, amino acids. Two ORFs show rather weak similarities to animal genes: YGR278w to an unknown ORF of Caenorhabditis elegans and YGR284c to the murine Surf-4, a member of a cluster of at least four housekeeping genes. The remaining five ORFs do not encode known functions, but three of these show weak to high similarities to other ORFs in the Saccharomyces cerevisiae genome and one (YGR280c) codes for a particularly lysine-rich protein. 相似文献
109.
S Probst-Cousin CH Rickert D Kunde KW Schmid F Gullotta 《Canadian Metallurgical Quarterly》1997,18(5):406-410
BACKGROUND: Polymorphonuclear elastase is an early and sensitive indicator of neonatal infection when performed at the beginning of clinical symptoms. PATIENTS AND METHODS: To investigate the diagnostic value of elastase measurement in cord blood immediately after birth, 211 neonates (103 boys vs 108 girls, 154 vaginal delivery vs 57 cesarean section). Mean gestational age 38.9 weeks (range: 30-42), mean birth weight 3,260 g (range: 1,430-4,920 g). After clinical, bacterial and biological screening, the infants were classified in three groups. Group A (n = 118): none infectious risk factor neither clinical signs of infection; group B (n = 79): one or more risk factors but no evidence of infection; group C (n = 14): proved or probable infection. Polymorphonuclear elastase was measured in cord blood of all infants using an heterogeneous enzyme-linked-immunosorbent assay. RESULTS: We observed higher elastase values in group C (176 +/- 67 micrograms/L) than in group A (91 +/- 64 micrograms/L) and B (67 +/- 61 micrograms/L) (mean +/- SD, P = 0.0001). With a cutoff value fixed at 80 micrograms/L, the sensitivity of this test applicated to neonates presenting materno-fetal infectious risk factor(s) was 85% (12/14), specificity 74% (59/79), positive predictive value 37%, and negative predictive value 96%. CONCLUSION: Because two of the 14 infected infants (15%) were not detected by elastase dosage in cord blood, this test cannot be used as an early indicator of materno-fetal infection. 相似文献
110.
Abstract Numerous ground-coupled air systems have been constructed in combination with heat recovery units in mechanically ventilated buildings in Switzerland. The objective of this study was to investigate the microbial content within these ventilation systems and to monitor the quality of the air supply. The concentrations and the types of microorganisms in the outdoor air, in the air of the pipes and in the supply air of twelve ground-coupled air systems were determined. In addition, three buildings were examined four times a year to cover seasonal changes. In general, the concentrations of fungal spores and bacteria in the air at the end of the underground pipes were lower than in the outdoor air, but great differences were observed between ventilation systems of large buildings and one-family houses. Occasionally, an increase in the concentration of Penicillium, Aspergillus or Actinomycetes was noted within a piping system. The concentrations in the supply air behind the filters were always low. Based on these investigations, the operation of ground-coupled air systems can be recommended as long as regular controls are undertaken and cleaning facilities are available. 相似文献