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主蒸汽压力是电厂热工过程控制中的重要参数,由于锅炉燃烧工况变化较大,主汽压对象模型具有不确定性,常规控制方法很难得到预期的控制效果。为提高系统控制品质,提出了主汽压系统的H∞混合灵敏度设计方法,给出了选择加权函数的具体方法,采用MATLAB软件进行仿真计算,得到H∞最优控制器。仿真结果表明,在对象模型参数发生较大变化时,与常规PID调节方法相比,H∞最优控制器能使主汽压控制系统具有良好的鲁棒稳定性和动态性能。 相似文献
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TiO2/α-Fe2O3复合光催化剂的制备及表征 总被引:3,自引:0,他引:3
用溶胶-凝胶法在α-FeOOH上负载TiO2,经过煅烧制备了TiO2/α-Fe2O3光催化剂.用Brunauer-Emmett-Teller(BET)法测试氮吸附比表面积.用X射线衍射、透射电镜、扫描电镜、Fourier转换红外光谱等研究了不同煅烧温度制备的光催化剂物相组成和形貌特征.研究了不同煅烧温度制备的光催化剂对活性艳蓝X-BR染料的吸附和光催化性能.结果表明:与未负载TiO2的α-FeOOH相比,经过复合、350℃煅烧制备的TiO2/α-Fe2O3复合材料的比表面积有了显著增加,从35.4m2/g增加到167.7m2/g,但是,当温度高于450℃时,其比表面积又有所下降.随着煅烧温度的增加,其负载的TiO2晶型由锐钛矿转变为金红石型,粒径也逐渐增大.在煅烧温度为350℃时,TiO2/α-Fe2O3催化剂吸附和光催化性能最好,脱色率可达到85.19%. 相似文献
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OBJECTIVES: Beta2-integrin (CD11b/CD18) expression, an indicator of neutrophil activation, has been associated with the development of acute respiratory distress syndrome. Leumedins act directly on leukocytes to inhibit the up-regulated expression of beta2-integrins involved in leukocyte adhesion. We examined the effect of such a new anti-inflammatory agent, NPC 15669 (N-[9H-(2,7-dimethylfluorenyl-9-methoxy)-carbonyl]-L-leucine), on neutrophil-mediated acute lung injury in an animal model. DESIGN: Prospective, randomized, blinded, controlled animal study. SETTING: An animal laboratory in a university setting. SUBJECTS: Adult New Zealand rabbits. INTERVENTIONS: After repeated lung lavages with normal saline to induce acute lung injury, anesthetized rabbits were randomly assigned to one of two groups (n = 6 per group): a) treatment group (pretreated with NPC 15669 [10 mg/kg i.v. bolus] 30 mins before lavage, followed by a continuous infusion [5 mg/kg/hr] for the duration [4 hrs] of the experiment); or b) control group (pretreatment and continuous infusion with placebo). All animals were mechanically ventilated with identical pressure settings over 4 hrs and were killed at the end of the experiment. MEASUREMENTS AND MAIN RESULTS: PaO2, PaCO2, and tidal volumes were repeatedly measured and airway pressure settings were noted every 30 mins. At the end of the experiment, lungs were taken out for measurements of the myeloperoxidase content, for conventional histology (hematoxylin and eosin staining), and for intracellular adhesion molecule-1 immunohistostaining. Pretreatment with NPC 15669 profoundly improved oxygenation from a PaO2 of 52 +/- 5 torr (6.9 +/- 0.7 kPa) to 250 +/- 161 torr (33.3 +/- 21.5 kPa) within 60 mins after lung lavage (p < .05). Oxygenation continued to improve throughout the study, reaching a maximal PaO2 value of 395 +/- 98 torr (52.7 +/- 13.1 kPa) at 4 hrs. In the control group, oxygenation remained poor throughout the observation period. PaO2 values differed significantly (51 +/- 20 torr [6.8 +/- 2.7 kPa] vs. 306 +/- 126 torr [40.8 +/- 16.8 kPa], p < .005) at 90 mins and at all subsequent measurements from those values in the NPC 15669 group. Dynamic lung compliance improved significantly 60 to 90 mins after repeated lung lavage. Histology demonstrated markedly less lung damage (hyaline membrane formation and leukocyte infiltration) in treated animals (p < .05) than in controls. CONCLUSIONS: NPC 15669 seems to block inflammatory reactions by inhibiting the sequestration of neutrophils in acute, ventilator-associated lung injury. As a result, gas exchange and total lung compliance improve. Application of this and similar compounds affecting neutrophil adhesion warrants further investigation as a treatment modality for acute lung injury. 相似文献
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MJ Feldhaus JM Kessel GA Zimmerman TM McIntyre 《Canadian Metallurgical Quarterly》1998,161(11):6280-6287
ICAM-3 is a preferred counterreceptor for the leukocyte alpha(L)beta2 integrin. It activates T cells through outside-in signaling, but polymorphonuclear leukocytes (PMN) are reported to be refractory to ICAM-3 stimulation. We found that engagement of ICAM-3 by a mAb (CAL3.10), which binds in the region where alpha(L)beta2 integrin binds, activates PMN homotypic aggregation and adhesion to surfaces. These functional changes were due to ICAM-3 outside-in signaling because aggregation and adhesion were beta2 integrin-dependent, tyrosine kinase and protein kinase C activities were activated, and there was a reorganization of the cytoskeleton. This reorganization and kinase activity was required for ICAM-3-, but not FMLP-, induced aggregation. This is not an Fc-mediated event as an appropriate anti-ICAM-3 F(ab')2 fragment still induced aggregation. Another anti-ICAM-3 Ab (HP2/19), which activates T cells, did not activate PMN. Strikingly, anti-ICAM-3 did not induce degranulation or cause an increase in surface beta2 integrin expression, so adhesion and aggregation were due solely to the activation of the constitutively expressed beta2 integrins. Aggregation in response to ICAM-3, but not FMLP, was compromised at lower cell densities, showing that beta2 integrin recruitment enhances aggregation under suboptimal conditions. We conclude that engagement of ICAM-3 stimulates PMN as well as T cells, but that the appropriate epitope varies between these two cells. ICAM-3 outside-in signaling reorganizes the cytoskeleton without causing degranulation, induces serine and tyrosine kinase activation, and activates existing surface beta2 integrins to a proadhesive state. 相似文献
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The microhaematocrit (MH) technique was used to study the survival of Trypanosoma evansi in blood from two herds of naturally-infected horses. A comparison was made between samples treated with ethylenediaminetetraacetic acid and sodium citrate (alone or with 1% glucose), and sent to the laboratory packed in ice. In general, the number of samples yielding positive results by the MH technique showed the least variation during the first 24-36 h after sample collection. Survival varied with the anticoagulant used, but it declined rapidly from 48 h after collection, although live parasites were still observed in up to 10% of samples until the seventh day. On the basis of the results obtained, the authors recommend the use of sodium citrate in treating equine blood samples for the parasitological diagnosis of T. evansi. 相似文献
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对硫酸庆大霉素/α半水硫酸钙载药体系进行了模拟条件下体外释药研究,并对其晶体结构进行了分析。X-射线衍射分析结果表明,载药体系中一定含量的硫酸庆大霉素不会影响α半水硫酸钙的水化;模拟条件下体外释药研究表明,各种药物含量的载药体系均表现出了良好的缓释性能,持续释放时间超过了360h;随着试样中载药量的增加,其药物释放速率加快;另外,构制了均一分散和核壳结构两种载药体系,研究结果表明,均一分散型在前期释放速度要大于核壳结构型,而后期核壳结构型则比均一分散型要高。 相似文献