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131.
In a study of the relationship of the tetrahydroisoquinolinecarboxylic acids (TIQCAs) to catecholamine metabolism, we have investigated their effects on cultured rat adrenal medulla explants. Medullae were incubated in medium containing norlaudanosolinecarboxylic acid (NLCA) or 3',4'-deoxynorlaudanosolinecarboxylic acid (DNLCA) (0.5 mM) in the presence and absence of [3H]tyrosine. By paired-ion reverse-phase high pressure liquid chromatography, tissue epinephrine (EPI), norepinephrine (NE), dopamine (DA) and TIQCA were resolved. Endogenous concentrations were measured with electrochemical detection, and radioactivity was assayed by collecting appropriate effluents. Tissue levels of the TIQCAs reached saturating levels of 0.36 mM by about 20 hr. DNLCA elicited a significant decrease (60%) in endogenous DA, NE and EPI at 40 hr, whereas only DA was depressed at 30 hr. NLCA had little effect after 30 or 40 hr. When tissues were maintained in the presence of alpha-methyltyrosine (0.5 mM) for 40 hr, catecholamine levels were depressed to an extent similar to that observed with DNLCA. Incubation with [3H]tyrosine in the presence of TIQCAs revealed inhibition of tyrosine uptake and suggested a reduction in the rate of catecholamine synthesis. These results are consistent with previous data on the inhibition of tyrosine 3-monooxygenase by DNLCA in vitro. 相似文献
132.
133.
Chompoonuch Puchmark Gobwute Rujijanagul Timothy P. Comyn Steven J. Milne 《Materials Research Bulletin》2007,42(7):1269-1277
Microstructures, Vickers hardness and dielectric properties of PbZrO3 ceramics with co-additions of 0.5-5 vol% Al2O3 nanoparticles have been investigated. The additive inhibited grain growth, with average grain size decreasing from ∼13 μm for PbZrO3 to ∼1 μm for the nanocomposites. The mode of fracture also changed, from predominantly inter-granular in PbZrO3 to a mixed-mode of intra- and inter-granular fracture in the composite samples. Vickers hardness values increased from 2.9 GPa for PbZrO3 to 4.1 GPa for the sample with 1 vol% Al2O3, but there was a more gradual increase for higher Al2O3 contents. Plots of relative permittivity versus temperature indicated subtle differences which were attributed to a chemical reaction between the additive and matrix during sintering. X-ray powder diffraction showed that lead aluminium oxides were the principal products of this reaction. 相似文献
134.
R. M. Lucas M. Honzák P. J. Curran G. M. Foody R. Milne T. Brown 《International journal of remote sensing》2013,34(15):2855-2881
The study aimed to map several stages of tropical forest regeneration across the Brazilian Legal Amazon using 1.1 km NOAA AVHRR data. Regenerating forest extent was defined using an unsupervised classification of AVHRR channels 1, 2 and 3 and the Global Environment Monitoring Index (GEMI). A method for discriminating four forest regeneration stages was then developed, based on relationships between AVHRR channels 1, 2 and 3 and forest age. This method was applied to AVHRR data to map forests associated with Stages I (early colonization phase, open canopy, < 5 years), II (closed, singlelayered canopy, 5-9 years), III (closed canopy with structural development, 9-20 years) and IV (closed multilayered canopy, > 20 years). The maps provided new regional estimates of regenerating forest for the Legal Amazon and indicated that, over the period 1991 to 1994, approximately 35.8% (157 973 km2) of the total deforested area of 440 186 km2 (estimated for 1992) supported regenerating forest, with 48% of these forests aged at less than 5 years. The study concluded that AVHRR data has an important role in mapping and monitoring tropical forest regeneration. The datasets generated provide valuable input to models of regional carbon flux. For example, Grace et al . (1995a, b) reported net annual CO2 absorption 8.5 2.0 moles m 2 for mature forests in south-west Amazonia suggesting 相似文献
135.
Y. Dong B. C. Forster A. K. Milne G. A. Morgan 《International journal of remote sensing》2013,34(2):317-330
An effective algorithm for digital image noise smoothing using wavelet transform techniques is presented in this paper. This algorithm is more powerful when compared to other existing filtering algorithms in terms of speckle suppression for synthetic aperture radar images where the presence of speckle makes the ratio of standard deviation to mean (STM) very high. Examples show that the original STM of about 0.30 (equivalent to three-look images) can be reduced to 0.05-0.03 (equivalent to more than 100-look images), with a possible small sacrifice of losing some details and narrow edges. The quantitative analysis is carried out and compared with the results of some existing filtering algorithms including median, K nearest neighbour averaging, Lee's multiplicative and Crimmins' geometric filters, showing that imagery filtered by the wavelet transform is the smoothest. 相似文献
136.
137.
MC Mahon MP Driscoll WJ Glover KM Borchert ZT Kelleher GJ Smith WB Coleman 《Canadian Metallurgical Quarterly》1999,14(2):337-346
We have previously identified and mapped a locus within human chromosome 11p11.2-p12 that suppresses the tumorigenic potential of a rat liver tumor cell line (termed GN6TF) which contains well defined chromosomal aberrations involving rat chromosomes 1, 4, 7, and 10. In the present study, we investigated the potential of this human 11p11.2-p12 liver tumor suppressor locus to suppress the tumorigenic potential of two other rat liver tumor cell lines (GN3TG and GP10TA) following microcell-mediated introduction of human chromosome 11. These tumor cell lines are aneuploid and contain chromosomal abnormalities that are similar to the GN6TF tumor line. The tumorigenic potential and other phenotypic characteristics of GN3TG-11neo and GP10TA-11neo microcell hybrid (MCH) cell lines were variable, and dependent upon the status of the introduced human chromosome 11. MCH cell lines that retained the region of 11p11. 2-p12 delineated by microsatellite markers D11S1385 and D11S903 exhibited suppression of tumorigenicity in vivo (decrease in tumorigenicity and/or elongation of latency), whereas, the tumorigenic potential of one MCH line that lacked markers in this region of human 11p11.2-p12, but retained flanking markers, was not changed from that of the parental tumor cell line. The chromosomal interval between microsatellite markers D11S1385 and D11S903 encompasses the previously localized minimal liver tumor suppressor region, suggesting that a common locus is responsible for tumor suppression among the rat liver tumor cell lines examined. The results of the present study have verified the presence of a liver tumor suppressor locus within human 11p11.2-p12, and have identified a substantial number of microsatellite markers that are closely linked to this tumor suppressor region. These chromosomal markers will facilitate positional cloning of candidate genes from this region, and may prove useful for determining the involvement of this locus in the pathogenesis of human liver cancer. 相似文献
138.
VS Kashyap WS Moore WJ Quinones-Baldrich 《Canadian Metallurgical Quarterly》1999,29(1):90-6; discussion 97-9
OBJECTIVE: The development of carotid atherosclerosis after neck irradiation is well documented. There has been concern about the safety and durability of carotid artery repair through a radiated field. The objective of this report is to describe the immediate and long-term results of a series of cases collected in a 13-year interval. METHODS: From 1984 to 1997, 24 patients underwent 26 carotid artery operations. All the patients had undergone prior radiation therapy at a mean interval of 17 years, with an average radiation dose of 6300 rad. Severe scarring of the skin or radiation fibrosis were present in two thirds of the patients, with 4 patients having permanent tracheostomies. The indications for carotid surgery included cerebral or monocular transient ischemic attack (58%), asymptomatic high-grade stenosis (27%), prior stroke (12%), and tumor invasion of the carotid artery (4%). General anesthesia was used with selective shunting on the basis of carotid artery back pressure or electroencephalography monitoring. Patch angioplasty closure was used in 79% of the patients. The operations included standard carotid endarterectomy (n = 20), external carotid endarterectomy (n = 2), carotid patch angioplasty alone (n = 2), aortocarotid bypass grafting (n = 1), and carotid interposition grafting (n = 1). Four patients required skin grafting or myocutaneous flaps. RESULTS: No deaths or strokes occurred within 30 days of the operations. Six patients had transient cranial nerve palsy, and two had wound infections. The patients were followed from 1 to 156 months, with six patients being followed for longer than 18 months. No strokes were seen at late follow-up examination. Duplex scan examination documented one occlusion, in a patient with primary closure, and two restenoses, one of which necessitated reoperation. The remainder of the grafts were widely patent. CONCLUSIONS: Carotid surgery after neck irradiation is safe and durable. The long-term patency rates and the protection against subsequent neurologic events are similar to the results obtained in the absence of radiation therapy. Problems of wound healing were not found in this series. 相似文献
139.
Films of silicon oxide have been produced by PECVD from NO + SiH4 mixtures. The results indicate that the film properties are less dependent on deposition conditions than when the more usual N2O + SiH4 mixtures are used. The films produced have a high resistivity and good interfacial properties with silicon, but are fairly porous with a relatively high etch rate in p-etch. 相似文献
140.
WJ Ellis RL Vessella JL Noteboom PH Lange RL Wolfert HG Rittenhouse 《Canadian Metallurgical Quarterly》1997,50(4):573-579
OBJECTIVES: Treatment failure after radical prostatectomy is most commonly heralded by an increase in serum prostate-specific antigen (PSA) to detectable levels. We evaluated the clinical utility of an ultrasensitive chemiluminescent PSA assay. METHODS: We evaluated the assay in banked sera obtained from 170 men after radical prostatectomy. Controls consisted of 142 females, 29 men who had undergone cystoprostatectomy without evidence of prostate cancer, and 25 men without evidence of recurrent disease at least 5 years after prostatectomy for organ-confined disease. Lead time to diagnosis of recurrence was based on comparisons with the IMx or Tandem E assays using a cutoff of 0.1 ng/mL (100 pg/mL). RESULTS: The biologic level of detection of this assay is 8 pg/mL. Serum PSA levels were undetectable in 82.4% of females, 86.2% of the cystoprostatectomy patients, and 96% of the radical prostatectomy controls. After radical prostatectomy, PSA levels were undetectable at last check in 104 of 168 (61.9%) men. In the 24 men with prostate cancer recurrence, the enhanced sensitivity of 8 pg/mL provided a mean lead time based on conservative calculations of 12.7 to 22.5 months over conventional assays. Thirty-four of the 41 men with detectable PSA levels and no evidence of disease recurrence had PSA levels of 30 pg/mL or less. CONCLUSIONS: PSA levels are undetectable in most men who do not have recurrence of disease after radical prostatectomy. Low but detectable serum PSA levels less than or equal to 30 pg/mL can be produced by nonmalignant sources of PSA. PSA assays with enhanced sensitivity can detect recurrent prostate cancer with significant lead time over conventional assays. 相似文献