全文获取类型
收费全文 | 1431篇 |
免费 | 96篇 |
专业分类
电工技术 | 31篇 |
综合类 | 1篇 |
化学工业 | 283篇 |
金属工艺 | 24篇 |
机械仪表 | 41篇 |
建筑科学 | 35篇 |
矿业工程 | 2篇 |
能源动力 | 57篇 |
轻工业 | 162篇 |
水利工程 | 10篇 |
石油天然气 | 1篇 |
无线电 | 163篇 |
一般工业技术 | 252篇 |
冶金工业 | 293篇 |
原子能技术 | 23篇 |
自动化技术 | 149篇 |
出版年
2023年 | 11篇 |
2022年 | 27篇 |
2021年 | 31篇 |
2020年 | 26篇 |
2019年 | 31篇 |
2018年 | 33篇 |
2017年 | 48篇 |
2016年 | 38篇 |
2015年 | 42篇 |
2014年 | 48篇 |
2013年 | 86篇 |
2012年 | 71篇 |
2011年 | 81篇 |
2010年 | 51篇 |
2009年 | 59篇 |
2008年 | 40篇 |
2007年 | 44篇 |
2006年 | 45篇 |
2005年 | 32篇 |
2004年 | 38篇 |
2003年 | 40篇 |
2002年 | 34篇 |
2001年 | 23篇 |
2000年 | 24篇 |
1999年 | 18篇 |
1998年 | 92篇 |
1997年 | 59篇 |
1996年 | 48篇 |
1995年 | 34篇 |
1994年 | 28篇 |
1993年 | 27篇 |
1992年 | 20篇 |
1991年 | 20篇 |
1990年 | 18篇 |
1989年 | 11篇 |
1988年 | 16篇 |
1987年 | 14篇 |
1986年 | 14篇 |
1985年 | 12篇 |
1984年 | 14篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 4篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1976年 | 14篇 |
1975年 | 9篇 |
1973年 | 4篇 |
1970年 | 2篇 |
排序方式: 共有1527条查询结果,搜索用时 0 毫秒
1.
A Burger D Voges P Demange CR Perez R Huber R Berendes 《Canadian Metallurgical Quarterly》1994,237(4):479-499
Annexin V binds to phospholipids in a calcium-dependent manner and exhibits calcium channel activity in vitro. We prepared a variety of mutants yielding information about the structure-function relationship of the ion channel activity. All mutants were characterized by X-ray crystallography, electron microscopy and electrophysiological measurements. Their structures are insignificantly changed whereas their electrophysiological properties are drastically different. Glu95, located in the central hydrophilic pore of the molecule, is crucial for the ion selectivity filter as its exchange leads to reduced calcium and increased sodium conductance. The removal of Glu17, located on the protein surface and far from the ion conduction pathway, leads to the appearance of a second conductance level of 9 pS in addition to the conductance level of about 30 pS in the wild-type molecule. This was also the case for Glu78, which is part of a weak calcium binding site. The exchange of Glu17 and Glu78 produced a mutant retaining only the smaller conductance level. We conclude that these two residues influence the angle between the two halves of the molecule, which determines the diameter of the ion conduction pathway, thereby leading to the occurrence of a second conductance level. 相似文献
2.
R Gouider E LeGuern J Emile S Tardieu F Cabon M Samid J Weissenbach Y Agid P Bouche A Brice 《Canadian Metallurgical Quarterly》1994,44(12):2250-2252
Fistulas secondary to Crohn's disease occur in about 33% of patients. A colobronchial fistula complicating Crohn's disease is very rare, having been reported only twice previously. We present an unusual fistula secondary to Crohn's colitis that originated from the splenic flexure and crossed the diaphragm to involve the bronchial tree. 相似文献
3.
4.
AJ Dorta M Ferra R Bu-Colfiu L García M Gil X Escobar G Martín NA Díaz OM Perez MT Interián 《Canadian Metallurgical Quarterly》1993,10(10):490-491
It is essential to know how the immune system acts in different neurological diseases, some of them non very well known or of unknown etiology at all. It was applied Reiber and Felgenhauer's formula in 56 patients with different diseases. IgA, IgM, IgG and albumin were quantified in sera and cerebrospinal fluid by simple immunodiffusion. It was observed more frequent IgG local synthesis and IgA in this sample. 相似文献
5.
A calorimetric measurement technique developed for NASA's Deep Space Network (DSN) transmitters that does not require data on the coolant's thermal parameters is described. Calibration of the measurement system is achieved by measuring the DC input power to the klystron and relating coolant temperature increase to this known power dissipation. Agreement between calorimetric and electrical measurements of total system power was good, the difference being less than 2%. The operation of the system was not greatly affected by the composition of the coolant, which was varied from pure water to 40% ethylene glycol by mass. Good accuracy was also shown at output power levels, which varied over a 3.6:1 range 相似文献
6.
We propose a new formulation for the Linke turbidity coefficient with the objective of removing its dependence upon solar geometry. In the process, we also develop two new simple clear sky models for global and direct normal irradiance. 相似文献
7.
In this note, we present a method to characterize the degradation in performance that arises in linear systems due to constraints imposed on the magnitude of the control signal to avoid saturation effects. We do this in the context of cheap control for tracking step signals. 相似文献
8.
Robin M. Giblin-Davis Jorge E. Peña A. C. Oehlschlager Alice L. Perez 《Journal of chemical ecology》1996,22(8):1389-1410
Response of adults of the West Indian sugarcane weevil,Metamasius hemipterus sericeus, to various semiochemical treatments and physical trap designs was studied in southern Florida in field-grown banana and Canary Island date palms. Ethyl acetate released alone at 860–1007 mg/day was as effective for the capture ofM. h. sericeus as a combination of ethyl acetate (844–919 mg/day), ethyl propionate (348–362 mg/day), and ethyl butyrate (117–137 mg/day) and in one trial was more effective than fermenting sugarcane (250 g), ethyl propionate alone (353–384 mg/day), ethyl butyrate alone (123–174 mg/day), or no treatment. Ethyl acetate released alone at 675–683 mg/day was as attractive as 250 g of fermenting sugarcane or the racemic blend of the male-produced aggregation pheromones [(±)-5-methyl-nonan-4-ol and (±)-2-methyl-heptan-4-ol (8:1 ratio) “metalure”] at 3 mg/day. Weevil counts increased with binary combinations of ethyl acetate, sugarcane, and/or metalure over these treatments alone and the ternary combination was two to three times more effective than any of the binary treatments. Attraction to ethyl acetate released alone at 777 mg/day with metalure was greater than to the hydrolysis products of ethyl acetate (ethanol and/or acetic acid each released at about 6–8 mg/day) with metalure. Weevil counts from traps baited with 250 g of sugarcane and metalure increased with increasing dose of ethyl acetate to about 400 mg/day and then appeared to plateau. Ethyl acetate (about 700 mg/day) and metalure increased weevil counts in traps with increasing amounts of sugarcane (0–2 kg). Molasses (45 g) + water (158 ml) substitutes for sugarcane were about as effective for capturingM. h. sericeus as 250 g of fermenting sugarcane [all treatments with ethyl acetate (847 mg/day) and metalure]. Early experiments used a lethal pitfall trap. We demonstrated that several alternative trap designs were more effective than the lethal pitfall trap for capturing weevils. Color and height (on ground vs. 1 m on pole) did not affect trap efficacy when baited with the ternary combination of ethyl acetate (672–825 mg/day), sugarcane (250 g), and metalure. 相似文献
9.
A mathematical model able to predict solid and drying gas temperature and moisture content axial profiles along a direct contact rotary dryer was developed. The study was focused on the drying kinetics based on phenomenological models. Two different drying mechanisms in the decreasing drying rate period were tested: proponional to the unbound moisture content and moisture diffusion inside the particle. Experimental data collected in a pilot-scale direct contact rotary dryer was used to validate the model. Soya and fish meals were used as drying material. 相似文献
10.
T. Perez M. Radziunas H.-J. Wunsche C.R. Mirasso F. Henneberger 《Photonics Technology Letters, IEEE》2006,18(20):2135-2137
We present numerical simulations describing the dynamics of two multisection semiconductor lasers emitting in a chaotic regime coupled in a master-slave configuration. By changing the current of the passive section of the master laser, we observe a change in the maximum correlation between the outputs of the two systems. These devices are promising candidates for on-off phase-shift keying encryption. 相似文献