全文获取类型
收费全文 | 375篇 |
免费 | 22篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 103篇 |
金属工艺 | 13篇 |
机械仪表 | 4篇 |
建筑科学 | 4篇 |
能源动力 | 5篇 |
轻工业 | 55篇 |
无线电 | 26篇 |
一般工业技术 | 58篇 |
冶金工业 | 73篇 |
原子能技术 | 6篇 |
自动化技术 | 44篇 |
出版年
2024年 | 3篇 |
2023年 | 3篇 |
2022年 | 8篇 |
2020年 | 2篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 5篇 |
2016年 | 8篇 |
2015年 | 12篇 |
2014年 | 20篇 |
2013年 | 25篇 |
2012年 | 18篇 |
2011年 | 19篇 |
2010年 | 14篇 |
2009年 | 21篇 |
2008年 | 15篇 |
2007年 | 17篇 |
2006年 | 16篇 |
2005年 | 16篇 |
2004年 | 10篇 |
2003年 | 8篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 8篇 |
1999年 | 1篇 |
1998年 | 26篇 |
1997年 | 20篇 |
1996年 | 9篇 |
1995年 | 9篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1987年 | 8篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 4篇 |
1976年 | 7篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有397条查询结果,搜索用时 15 毫秒
51.
A Bucciero ML De Caro E Tedeschi L Vizioli A Cerillo G Tedeschi 《Canadian Metallurgical Quarterly》1997,52(6):863-866
A number of radon-related properties have been surveyed in underground shopping centers in Hong Kong. These parameters include the radon concentration, the total potential alpha energy concentration of radon progeny, the equilibrium factor and the unattached fraction of radon progeny. The mean values recorded for these were 29.2 +/- 7.8 Bq/m3, 3.60 +/- 1.53 mWL, 0.46 +/- 0.16 and 0.05 +/- 0.03, respectively. Based on these figures, we have calculated the average radon dose received by employees in an underground shopping center in Hong Kong to be 0.22 mSv/yr, which represents an approximate increase of 8% over the total dose of about 2.7 mSv/yr received by the average person in Hong Kong. 相似文献
52.
The antihypoxic, anti-ischemic and antianginal activity of biotechnological cytochrome c which had been immobilized on a dialdehydedextran and polyethyleneglycol carriers was studied in various experimental animals (mice, rats, rabbits). The immobilized cytochrome c exhibits higher antihypoxic and anti-ischemic activity on different models compared to cytochrome c. 相似文献
53.
R Ciccocioppo I Panocka C Polidori G De Caro D Regoli M Massi 《Canadian Metallurgical Quarterly》1997,18(9):1349-1355
Injections in the nucleus basalis magnocellularis (NBM) of the tachykinin (TK) NK-3 receptor agonist [Asp5,6,MePhe8]substance P(5-11), also referred to as amino-senktide (NH2-SENK), markedly reduced alcohol intake in genetically selected alcohol-preferring rats, offered 10% ethanol 2 h/day. The threshold dose in the NBM was 0.5 ng/site, while neither 1 nor 10 ng/rat of NH2-SENK inhibited alcohol intake following administration into the lateral ventricle. Injection of NH2-SENK, 25 ng/site, in the NBM did not modify water or food intake in water deprived rats, providing evidence for the behavioral selectivity of the effect on ethanol intake. The selective TK NK-3 receptor antagonist, R-820, injected in the NBM at the dose of 1000 ng/site 5 min before NH2-SENK 5 ng/site, significantly reduced the effect of NH2-SENK. The selective TK NK-1 receptor agonist [Sar9,Met(O2)11]substance P inhibited alcohol intake following injection in the NBM only at 25 ng/site; but the same dose induced marked grooming and inhibited also water intake in water deprived rats. The present results confirm that TK NK-3, but not NK-1, receptor agonists selectively inhibit ethanol intake in alcohol-preferring rats and suggest that the NBM is a site of action for their effect. 相似文献
54.
AN Barkun JS Barkun JS Sampalis J Caro GM Fried JL Meakins L Joseph CA Goresky 《Canadian Metallurgical Quarterly》1997,13(4):589-601
Thirty-five patients were randomized to extracorporeal shock-wave lithotripsy (ESWL) and 25 to laparoscopic cholecystectomy (LC). Stone disappearance occurred in only 12 of 32 ESWL patients [38% (95% CI: 21-56%)] during a 15-month follow-up. Greater incremental gains in quality of life after 6 months were observed among LC patients (p < .01). Total duration of disability was 6.8 +/- 8.5 days for ESWL, and 22.7 +/- 16.6 days for LC (p < .01). Nine (28%) patients crossed over electively to the LC group, but only 44% of these underwent LC within the next 3 years. ESWL cost Can $58.9/ day of disability saved. ESWL is limited by its selective applicability and modest stone disappearance rate. Its cost-effectiveness is largely dependent on patient acceptance of recurrent episodes of biliary colic due to the persistence of stone fragments. 相似文献
55.
The single-pore model for gas-solid reactions proposed by Ramachandran and Smith[1] is used to develop exact, closed-form solutions for the concentrati pore radius and conversion profiles in a long, narrow pore for both cylindrical and slab geometries. For relatively large values of the Thiele modulus, the solutions portray the asymptotic behavior of the reaction scheme in a finite pore. The cases of incomplete conversion associated with pore closure low initial porosities and complete conversion associated with a moving reaction zone at high initial porosities are analyzed. It is shown that the asy results provide very accurate estimates of the overall conversion in applications involving large pore diffusional resistance or fast reactions. The se of the conversion to various physicochemical parameters is also examined. The asymptotic results show good agreement with experimental data for gas-sol 相似文献
56.
The histidine decarboxylase activity has been studied in the H-110 Lymphoma implanted in Balb-c mice. The enzymatic activity has been determined using DL-Histidine 1-14C by measuring the I--14CO2 liberated during the incubation. It has been found that the histidine decarboxylase activity in the tumor is the highest of the studied tissues. The pretreatment for 5 days with two cytostatic drugs, cyclophosphamide and 5-fluoruracile, determined a decrease of the enzymatic activity in the tumor of 33 and 54 per cent, respectively. This effect has not been observed in the lung. The pretreatment of the animals during 10 days with 0.1 mg per kg body of histamine, which in other experimental tumors induces an increase of the endogenous content of histamine, produces a decrease of the tumoral histidine decarboxylase activity. The histamine-14C uptake was not modified by this pretreatment. The subcellular localization of the radioactivity after pretreatment with histamine-14C evidenced that the nuclear fraction of the tumor contained between 2 and 10 times the radioactivity of other tissues of the same animal. 相似文献
57.
The individual and combined influence on the bleaching of wool of the concentration of hydrogen peroxide, temperature and time of treatment have been studied, using a rotatable central design of experiments in which the values of the above variables covered the values used in industry. Mathematical treatment of the values of the optical, chemical and mechanical parameters has enabled equations to be derived, from which the value of any parameter can be computed when the values of the variables are within the range of the plan of experiments, resulting in a good agreement being obtained between experimental and calculated values. Use of these equations facilitates optimization of the process of wool bleaching, and bleaching conditions leading to the whitest wool have been suggested for an allowable chemical degradation (alkali solubilities of 25%and 30%). More severe conditions of bleaching do not necessarily produce a whiter wool, but cause greater chemical and mechanical degradation of the fibre. An excellent linear correlation has been found between the chemical parameters modified by the bleaching operation and between these and the wet tensile strength of the fibre. 相似文献
58.
Platelets of lanthanum oxysulphide were deformed inside the electron microscope and observed in transmission. Dislocations very mobile along the basal plane and having a Burgers vector in this plane, have been observed. The dislocations are dissociated into ribbons consisting of two partials separated by a stacking fault. Interactions between sets of ribbon dislocations with Burgers vector at 120° resulted in the formation of networks which, because of the low stacking fault energy in this material, consisted of a triangular mosaic pattern. A specific model for these dislocations is presented. It results from translation between adjacent sulfur and [LaO]n+n sheets. 相似文献
59.
A twenty-nine-year-old woman had a history of recurring gross, total painless hematuria. The past history and urologic studies supported the diagnosis of hemangioma of the bladder. A partial cystectomy was performed. The pertinent literature is reviewed. 相似文献
60.
Concentrations in air of (Z)-9-tetradecen-1-ol formate (Z-9-tdf), a mating disruptant ofHeliothis moths, were measured intermittently over a 22-day period in a corn field. The chemical was emitted from laminated plastic (Hercon®) dispensers arranged in a square grid with 10-m spacing. Measurements were made at three heights near the center of the treated plot and 1 m downwind from disruptant dispensers. Concurrent measurements were made of wind speed, air temperature, and temperature gradient.Z-9-tdf concentrations ranged from below detectable levels to 195 ng/m3 and were generally highest in the horizontal plane of the dispenser. As wind speed decreased near sunset, concentrations increased sharply, then decreased again near midnight. SinceHeliothis moths mate in the evening and early night, the concentration pattern was favorable for mating disruption. Strong temperature inversions within the crop canopy, which occurred daily before sunset, did not apparently affectZ-9-tdf concentrations. Concentrations decreased steadily on successive sampling days after application, and, by day 27, ranged from 0 to 30% of those on day 6. The data suggest that the corn plants and the soil may act as sinks for the chemical vapor at night. 相似文献