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21.
研究了添加BaO、CaO、MgO对B2O3-Al2O3-SiO2系统玻璃析晶性能的影响。用DSC测试了玻璃的析晶温度,用XRD分析了玻璃析晶后的晶相组成,用SEM观察了析出晶粒的形貌特征。结果表明:BaO、CaO均可有效促进BAS玻璃的形成,而MgO易导致玻璃分相。MO-BAS玻璃的析晶温度在770~810℃之间。添加BaO时析出的主晶相为硼酸铝(Al18B4O33)和少量勃来石(Al16B6Si2O37),以针柱状晶为主。用CaO替代BaO,析出的主晶相不变,但析晶能力增加,以细小的粒状晶为主。添加MgO时析出的主晶相为偏硼酸铝(Al4B2O9)和勃来石,晶粒较粗大。 相似文献
22.
制备高强石膏是磷石膏资源化的重要途经。为实现磷石膏资源化,采用蒸压水溶液法,以硫酸铝、草酸钾及其共混物为转晶剂,在蒸压温度为130℃、保温时间为6 h、液固质量比为0.5条件下制备了α-半水石膏。讨论了不同转晶剂对α-半水石膏形貌和力学性能的影响。结果表明,以硫酸铝为转晶剂时,所制备试样的形貌随转晶剂掺量的增大呈现由针状向长柱状、小晶粒向大晶粒发展的趋势,而以草酸钾为转晶剂制备的试样形貌多为短柱状、晶粒大小不一。当转晶剂总量为石膏量的0.6%、硫酸铝与草酸钾掺量比为5∶1时所制备的石膏试样具有晶粒尺寸大、晶体形貌规整(六方状晶体)的特点,其2 h抗折强度和2 d绝干抗压强度分别可达5.88、36.90 MPa。 相似文献
23.
A new feature selection method is proposed for high-dimensional data clustering on the basis of data field. With the potential entropy to evaluate the importance of feature subsets, features are filtered by removing unimportant features or noises from the original datasets. Experiments show that the proposed method can sharply reduce the number of dimensions and effectively improve the clustering performance on WDBC dataset. 相似文献
24.
为解决因大孔隙与高压缩引起土的强度降低问题,采用棕榈加筋上海粘土来提高其强度。选择棕榈加筋率、加筋尺寸作为影响因素,对其进行直剪慢剪、CBR及无侧限抗压强度的试验研究。试验结果表明:棕榈加筋土能够显著提高上海粘土抗剪强度、抗压强度及抗变形能力。最适宜的棕榈加筋尺寸为6 mm×12 mm。直剪慢剪试验的最佳加筋率为0.6%,CBR及无侧限抗压强度试验的最佳加筋率为0.8%。同时通过试验研究,分析加筋土强度变化的原因,掌握棕榈加筋对上海粘土影响的变化规律。 相似文献
25.
Tobias Hanning René Schöne Georg Pisinger 《Journal of Mathematical Imaging and Vision》2006,25(1):5-23
In this article we present an approach to the segmentation problem by a piecewise approximation of the given image with continuous functions. Unlike the common approach of Mumford and Shah in our formulation of the problem the number of segments is a parameter, which can be estimated. The problem can be stated as: Compute the optimal segmentation with a fixed number of segments, then reduce the number of segments until the segmentation result fulfills a given suitability. This merging algorithm results in a multi-objective optimization, which is not only resolved by a linear combination of the contradicting error functions. To constrain the problem we use a finite dimensional vector space of functions in our approximation and we restrict the shape of the segments. Our approach results in a multi-objective optimization: On the one hand the number of segments is to be minimized, on the other hand the approximation error should also be kept minimal. The approach is sound theoretically and practically: We show that for L 2-images a Pareto-optimal solution exists and can be computed for the discretization of the image efficiently. 相似文献
26.
27.
R Parry D Plowman HT Delves NB Roberts JD Birchall JP Bellia A Davenport R Ahmad I Fahal P Altmann 《Canadian Metallurgical Quarterly》1998,13(7):1759-1762
BACKGROUND: Aluminium toxicity in dialysis patients is well described. Aluminium has a close chemical affinity with silicon. Silicon may have a role in protection against aluminium toxicity. METHODS: We measured serum aluminium and silicon levels from haemodialysis patients from four different centres. RESULTS: Though no relationship was seen across all centres combined, in one centre there was a reciprocal relationship in patients on home haemodialysis (who did not require reverse osmosis). Median (range) aluminium levels were higher, 2.2 (0.4-9.6) micromol/l when serum silicon was less than 150 micromol/l, and lower, 1.1 (0.2-2.8) micromol/l when serum silicon levels were greater than 150 micromol/l (P = 0.03). CONCLUSIONS: In patients treated by haemodialysis without reverse osmosis high serum silicon concentrations were associated with lower serum aluminium concentrations than those with low serum silicon. Further work needs to confirm a preventative role for silicon in the accumulation and subsequent toxicity of aluminium in dialysis patients. 相似文献
28.
EM Burtsev LA Zhdanova TV Riabchikova EV Batanova NB Fokina GN Gromtseva 《Canadian Metallurgical Quarterly》1998,98(9):9-11
90 infants with intrauterine growth retardation (IGR) and 100 normal infants (control group) were followed up from 5 days till 3 years of life. In IGR infants there was a more frequent combination of several neurologic syndromes, an early manifestation of motor disorders (from the very moment of birth), a delay of neuro-psychic development (during the first year of life), a tendency to development of moderate hydrocephalus by the age of 6 months. Autonomic-visceral disorders in them were mostly characterized by the symptoms of abaissement, but not of irritation. 相似文献
29.
GL DeNardo SJ DeNardo DS Goldstein LA Kroger KR Lamborn NB Levy JP McGahan Q Salako S Shen JP Lewis 《Canadian Metallurgical Quarterly》1998,16(10):3246-3256
PURPOSE: Lym-1, a monoclonal antibody that preferentially targets malignant lymphocytes, has induced remissions in patients with non-Hodgkin's lymphoma (NHL) when labeled with iodine 131 ((131)I). Based on the strategy of fractionating the total dose, this study was designed to define the maximum-tolerated dose (MTD) and efficacy of the first two, of a maximum of four, doses of (131)I-Lym-1 given 4 weeks apart. Additionally, toxicity and radiation dosimetry were assessed. MATERIALS AND METHODS: Twenty patients with advanced NHL entered the study a total of 21 times. Thirteen (62%) of the 21 entries had diffuse large-cell histologies. All patients had disease resistant to standard therapy and had received a mean of four chemotherapy regimens. (131)I-Lym-1 was given after Lym-1 and (131)I was escalated in cohorts of patients from 40 to 100 mCi (1.5 to 3.7 GBq)/m2 body surface area. RESULTS: Mean radiation dose to the bone marrow from body and blood (131)I was 0.34 (range, 0. 1 6 to 0.63) rad/mCi (0.09 mGy/MBq; range, 0.04 to 0.17 mGy/ MBq). Dose-limiting toxicity was grade 3 to 4 thrombocytopenia with an MTD of 100 mCi/m2 (3.7 GBq/m2) for each of the first two doses of (131)I-Lym-1 given 4 weeks apart. Nonhematologic toxicities did not exceed grade 2 except for one instance of grade 3 hypotension. Ten (71 %) of 14 entries who received at least two doses of (131)I-Lym-1 therapy and 11 (52%) of 21 total entries responded. Seven of the responses were complete, with a mean duration of 14 months. All three entries in the 100 mCi/m2 (3.7 MBq/m2) cohort had complete remissions (CRs). All responders had at least a partial remission (PR) after the first therapy dose of (131)I-Lym-1. CONCLUSION: (131)I-Lym-1 induced durable remissions in patients with NHL resistant to chemotherapy and was associated with acceptable toxicity. The nonmyeloablative MTD for each of the first two doses of (131)I-Lym-1 was 100 mCi/m2 (total, 200 mCi/m2) (3.7 GBq/m2; total, 7.4 GBq/m2). 相似文献
30.
NB Cummings 《Canadian Metallurgical Quarterly》1998,7(2):173-176
Distribution of markers of local cell-mediated immunity was examined in oral tumors exhibiting different histological stages of differentiation. Using a RT-PCR-based semiquantitative technique we determined levels of Langerhans cells, CD4- and CD8-positive T-cells, macrophages/NK cells, beta2-microglobulin and IFN-gamma mRNAs from tissue biopsies. A positive correlation was found between levels of these immunological markers and the tumor differentiation stage. Since tumor differentiation may correlate with the prognosis and response to various treatment modalities, our results may be useful clinically. 相似文献