全文获取类型
收费全文 | 30293篇 |
免费 | 1699篇 |
国内免费 | 26篇 |
专业分类
电工技术 | 164篇 |
综合类 | 10篇 |
化学工业 | 5566篇 |
金属工艺 | 420篇 |
机械仪表 | 557篇 |
建筑科学 | 811篇 |
矿业工程 | 52篇 |
能源动力 | 506篇 |
轻工业 | 5478篇 |
水利工程 | 309篇 |
石油天然气 | 119篇 |
武器工业 | 1篇 |
无线电 | 1041篇 |
一般工业技术 | 4311篇 |
冶金工业 | 9054篇 |
原子能技术 | 65篇 |
自动化技术 | 3554篇 |
出版年
2024年 | 66篇 |
2023年 | 277篇 |
2022年 | 271篇 |
2021年 | 715篇 |
2020年 | 655篇 |
2019年 | 670篇 |
2018年 | 1236篇 |
2017年 | 1206篇 |
2016年 | 1256篇 |
2015年 | 964篇 |
2014年 | 1105篇 |
2013年 | 2297篇 |
2012年 | 1761篇 |
2011年 | 1554篇 |
2010年 | 1265篇 |
2009年 | 1083篇 |
2008年 | 1147篇 |
2007年 | 1046篇 |
2006年 | 666篇 |
2005年 | 557篇 |
2004年 | 535篇 |
2003年 | 515篇 |
2002年 | 429篇 |
2001年 | 323篇 |
2000年 | 261篇 |
1999年 | 446篇 |
1998年 | 3098篇 |
1997年 | 1936篇 |
1996年 | 1190篇 |
1995年 | 614篇 |
1994年 | 507篇 |
1993年 | 532篇 |
1992年 | 106篇 |
1991年 | 102篇 |
1990年 | 94篇 |
1989年 | 104篇 |
1988年 | 111篇 |
1987年 | 99篇 |
1986年 | 82篇 |
1985年 | 95篇 |
1984年 | 62篇 |
1983年 | 39篇 |
1982年 | 49篇 |
1981年 | 82篇 |
1980年 | 86篇 |
1978年 | 33篇 |
1977年 | 161篇 |
1976年 | 336篇 |
1975年 | 35篇 |
1973年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
BS Kendrick BS Chang T Arakawa B Peterson TW Randolph MC Manning JF Carpenter 《Canadian Metallurgical Quarterly》1997,94(22):11917-11922
Understanding the mechanism for sucrose-induced protein stabilization is important in many diverse fields, ranging from biochemistry and environmental physiology to pharmaceutical science. Timasheff and Lee [Lee, J. C. & Timasheff, S. N. (1981) J. Biol. Chem. 256, 7193-7201] have established that thermodynamic stabilization of proteins by sucrose is due to preferential exclusion of the sugar from the protein's surface, which increases protein chemical potential. The current study measures the preferential exclusion of 1 M sucrose from a protein drug, recombinant interleukin 1 receptor antagonist (rhIL-1ra). It is proposed that the degree of preferential exclusion and increase in chemical potential are directly proportional to the protein surface area and that, hence, the system will favor the protein state with the smallest surface area. This mechanism explains the observed sucrose-induced restriction of rhIL-1ra conformational fluctuations, which were studied by hydrogen-deuterium exchange and cysteine reactivity measurements. Furthermore, infrared spectroscopy of rhlL-1ra suggested that a more ordered native conformation is induced by sucrose. Electron paramagnetic resonance spectroscopy demonstrated that in the presence of sucrose, spin-labeled cysteine 116 becomes more buried in the protein's interior and that the hydrodynamic diameter of the protein is reduced. The preferential exclusion of sucrose from the protein and the resulting shift in the equilibrium between protein states toward the most compact conformation account for sucrose-induced effects on rhIL-1ra. 相似文献
13.
14.
H Sawert E Girardi G Antonucci MC Raviglione P Viale G Ippolito 《Canadian Metallurgical Quarterly》1998,158(19):2112-2121
15.
16.
R Herruzo-Cabrera L Malo-González ME Calle Purón MJ Vizcaíno-Alcaide J Del Rey-Calero 《Canadian Metallurgical Quarterly》1993,9(4):442-446
A cross-sectional study was performed to obtain risk factors for hepatitis B disease, HBsAg carriers and immunised personnel, among 2470 workers in a general hospital in Madrid, Spain. The data obtained were analyzed with multiple logistic regression to obtain beta coefficients for variables. The results of the analysis show that being a nurse or being regularly exposed to blood are the most important risk factors for hepatitis B acquisition. The length of time working at the same job activity was also a risk factor. The resulting beta coefficients allow the construction for a hepatitis non-immunised, HBsAg carrier and immunised HBV status, which can select subjects for a hepatitis B vaccination program. 相似文献
17.
María P. Albano Liliana B. Garrido 《Journal of Materials Synthesis and Processing》2002,10(4):211-218
Si3N4powders coated with 6 wt% Y2O3and 4 wt% Al2O3were prepared by coprecipitation. The resulting powders were dispersed in water at different pH values and with addition of various amounts of ammonium polyacrylate (NH4PA) to produce 32 vol% slips. The influence of the amount of NH4PA solution added and pH on the rheological properties of 32 vol% coated Si3N4slips were studied. In addition, the sintered density of cast samples was determined and related to the degree of slip dispersion. The adsorption of the NH4PA on the coated particle surface was rather high and the surface became saturated near 0.86 mg/m2at pH 9.2. High NH4PA concentrations (1.7–3 wt%) were necessary to obtain well dispersed 32 vol% coated Si3N4slips at pH 9.2. The best stabilization was obtained with the addition of 2.3 wt% NH4PA; in this condition, the viscosity reached a minimum value of 35 mPa.s at 100 s–1. The slip viscosity increased with increasing pH from 9.2 to 10.2. Slips with low viscosities gave a more dense packing of cast samples and consequently higher sintered density values. 相似文献
18.
19.
Generation of Technology-Independent Retargetable Analog Blocks 总被引:1,自引:0,他引:1
R. Castro-López F. V. Fernández F. Medeiro A. Rodríguez-Vázquez 《Analog Integrated Circuits and Signal Processing》2002,33(2):157-170
This paper introduces a complete methodology for retargeting of analog cells to different sets of specifications. This methodology is technology-independent, thus allowing the migration, from one technology to another, of the circuit under retargeting. Careful integration of the device sizing and layout generation tasks via the incorporation of layout constraints during the sizing process allows to generate fully functional designs in a few minutes. The methodology is illustrated via the retargeting of a fully-differential Miller-compensated two-stage operational amplifier for a new set of specifications and two different technological processes.An erratum to this article can be found at 相似文献
20.
Kunkel Mark A.; Hector Mark A.; Góngora Coronado Elías; Castillo Vales Victor 《Canadian Metallurgical Quarterly》1989,36(3):322
Conducted a study of client expectations of psychological services in Yucatán, Mexico, under the sponsorship of a grant from the Organization of American States. The Expectations about Counseling–Brief form (EAC-B) questionnaire was translated and administered to 488 subjects across age, sex, and experience with psychological services. Subsequent analyses supported the reliability and robustness of the Spanish EAC-B, with factor structure similar to the EAC-B in English. Some relation was found among age, sex, prior counseling experience, and expectations about counseling. Implications of these data for future research and comparison with U.S. subjects are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献