全文获取类型
收费全文 | 2824篇 |
免费 | 36篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 4篇 |
综合类 | 2篇 |
化学工业 | 95篇 |
金属工艺 | 25篇 |
机械仪表 | 17篇 |
建筑科学 | 5篇 |
能源动力 | 17篇 |
轻工业 | 97篇 |
无线电 | 70篇 |
一般工业技术 | 123篇 |
冶金工业 | 2349篇 |
原子能技术 | 4篇 |
自动化技术 | 57篇 |
出版年
2023年 | 2篇 |
2022年 | 11篇 |
2021年 | 4篇 |
2020年 | 12篇 |
2019年 | 19篇 |
2018年 | 11篇 |
2017年 | 25篇 |
2016年 | 15篇 |
2015年 | 22篇 |
2014年 | 26篇 |
2013年 | 34篇 |
2012年 | 27篇 |
2011年 | 33篇 |
2010年 | 24篇 |
2009年 | 26篇 |
2008年 | 25篇 |
2007年 | 17篇 |
2006年 | 27篇 |
2005年 | 17篇 |
2004年 | 13篇 |
2003年 | 15篇 |
2002年 | 11篇 |
2001年 | 24篇 |
2000年 | 11篇 |
1999年 | 95篇 |
1998年 | 742篇 |
1997年 | 463篇 |
1996年 | 280篇 |
1995年 | 165篇 |
1994年 | 119篇 |
1993年 | 162篇 |
1992年 | 22篇 |
1991年 | 22篇 |
1990年 | 29篇 |
1989年 | 18篇 |
1988年 | 15篇 |
1987年 | 19篇 |
1986年 | 21篇 |
1985年 | 12篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 14篇 |
1981年 | 12篇 |
1980年 | 21篇 |
1979年 | 1篇 |
1978年 | 5篇 |
1977年 | 53篇 |
1976年 | 115篇 |
1975年 | 1篇 |
1955年 | 4篇 |
排序方式: 共有2865条查询结果,搜索用时 13 毫秒
1.
Dong-Soo Yoon Jae Sung Roh Sung-Man Lee Hong Koo Baik 《Journal of Electronic Materials》2003,32(8):890-898
The effect of a thin RuOx layer formed on the Ru/TiN/doped poly-Si/Si stack structure was compared with that on the RuOx/TiN/doped poly-Si/Si stack structure over the post-deposition annealing temperature ranges of 450–600°C. The Ru/TiN/poly-Si/Si
contact system exhibited linear behavior at forward bias with a small increase in the total resistance up to 600°C. The RuOx/TiN/poly-Si/Si contact system exhibited nonlinear characteristics under forward bias at 450°C, which is attributed to no
formation of a thin RuOx layer at the RuOx surface and porous-amorphous microstructure. In the former case, the addition of oxygen at the surface layer of the Ru film
by pre-annealing leads to the formation of a thin RuOx layer and chemically strong Ru-O bonds. This results from the retardation of oxygen diffusion caused by the discontinuity
of diffusion paths. In particular, the RuOx layer in a nonstoichiometric state is changed to the RuO2-crystalline phase in a stoichiometric state after post-deposition annealing; this phase can act as an oxygen-capture layer.
Therefore, it appears that the electrical properties of the Ru/TiN/poly-Si/Si contact system are better than those of the
RuOx/TiN/poly-Si/Si contact system. 相似文献
2.
In this study, the effect and side-effect of epidural injection with lappaconitine compound for post-operative analgesia was observed. One hundred and twenty patients were randomly divided into 4 groups. Lappaconitine compound (LB) consisted of 12 mg of lappaconitine and 22.5 mg of bupivacaine, was given to group A (the group of observation), and lappaconitine 12 mg, bupivacaine 22.5 mg and morphine 2 mg to group B, C and D respectively for control. All were given by epidural injection with single blind method during post-operative pain of incision operation. Result showed that the initiating of analgesia was quicker in group A and C than that in group B and D, and the efficacy was group D > A > C > B. There was significant difference between group A and B in the above two parameters, P < 0.01 and P < 0.05. The analgisia maintenence time of single injection was D > A > B > C, that of group D was significantly longer than that of group A (P < 0.01). It indicated that the epidural injection with LB was more rapid and potent than that with lappaconitine alone in post-operative analgesia, and the former had no side-effect, it was safer than morphine. 相似文献
3.
Boundary element analysis of thermal stress intensity factors for interface griffith and cusp cracks
Kang Yong Lee
Woon Cheon Baik
《Engineering Fracture Mechanics》1994,47(6):909-918The thermal stress intensity factors for interface cracks of Griffith and symmetric lip cusp types under vertical uniform heat flow in a finite body are calculated by the boundary element method. The boundary conditions on the crack surfaces are insulated or fixed to constant temperature. The relationship between the stress intensity factors and the displacements on the nodal point of a crack-tip element is derived. The numerical values of the thermal stress intensity factors for an interface Griffith crack in an infinite body are compared with the previous solutions. The thermal stress intensity factors for a symmetric lip cusp interface crack in a finite body are calculated with respect to various effective crack lengths, configuration parameters, material property ratios and the thermal boundary conditions on the crack surfaces. Under the same outer boundary conditions, there are no appreciable differences in the distribution of thermal stress intensity factors with respect to each material property. However, the effect of crack surface thermal boundary conditions on the thermal stress intensity factors is considerable. 相似文献
4.
5.
6.
MG McInnis A Chakravarti J Blaschak MB Petersen V Sharma D Avramopoulos JL Blouin U K?nig C Brahe TC Matise 《Canadian Metallurgical Quarterly》1993,16(3):562-571
A genetic linkage map of human chromosome 21q (HC21q) containing 43 markers genotyped by the polymerase chain reaction in the CEPH pedigrees is presented. The markers placed on this map are highly polymorphic with an average heterozygosity of 61%. The average interval size of the markers localized at 1000:1 odds is 2.5 cM. The map has a total length of 65.5 cM, with male and female lengths of 47.7 and 83.3 cM, respectively. The genotypes used in the construction of this map were subjected to rigorous error checking, which is reflected in the shorter map length compared to previous maps; the estimated error rate in genotyping is less than 0.04%. As noted in previous linkage maps there is increased recombination in females on proximal HC 21q and in the male in a region near the telomere. This map of HC 21 represents a highly informative and dense meiotic linkage map and will be useful in linking disease phenotypes to loci on this chromosome. 相似文献
7.
8.
9.
MG Newman 《Canadian Metallurgical Quarterly》1997,2(1):180-198
The design and implementation of clinical trials (CTs) carried out to evaluate antimicrobial and anti-infective drugs and devices are one of the most difficult challenges in contemporary periodontal research and product development. The overwhelming amount of evidence which has established a microbial etiology for periodontitis is the basis for developing and testing antimicrobial treatments. Well-designed antimicrobial CTs start with a carefully crafted hypothesis and a protocol which explicitly integrates the requirements of the patient, the clinician, the sponsor, and regulatory authorities. Surrogate variables for effectiveness must be clinically relevant, scientifically sound, and statistically valid. Currently, clinical attachment level measurements and alveolar bone assessments are accepted as proof of effectiveness. Indication and claim support of the antimicrobial product guide the design and implementation of the CT. Adverse microbiologic consequences, such as lack of antimicrobial susceptibility, wrong spectrum, incorrect dosage, non-compliance, and drug interference, must be monitored. Successful CTs balance a large group of variables used to screen, randomize, and assign subjects to experimental and control groups to ensure that prognostic and risk factors are properly accounted for. 相似文献
10.