全文获取类型
收费全文 | 3431篇 |
免费 | 91篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 44篇 |
综合类 | 1篇 |
化学工业 | 709篇 |
金属工艺 | 58篇 |
机械仪表 | 59篇 |
建筑科学 | 49篇 |
矿业工程 | 3篇 |
能源动力 | 91篇 |
轻工业 | 202篇 |
水利工程 | 12篇 |
石油天然气 | 7篇 |
无线电 | 301篇 |
一般工业技术 | 524篇 |
冶金工业 | 1146篇 |
原子能技术 | 27篇 |
自动化技术 | 298篇 |
出版年
2023年 | 27篇 |
2022年 | 61篇 |
2021年 | 76篇 |
2020年 | 70篇 |
2019年 | 65篇 |
2018年 | 85篇 |
2017年 | 60篇 |
2016年 | 62篇 |
2015年 | 57篇 |
2014年 | 78篇 |
2013年 | 174篇 |
2012年 | 105篇 |
2011年 | 108篇 |
2010年 | 75篇 |
2009年 | 87篇 |
2008年 | 85篇 |
2007年 | 74篇 |
2006年 | 84篇 |
2005年 | 59篇 |
2004年 | 44篇 |
2003年 | 45篇 |
2002年 | 45篇 |
2001年 | 23篇 |
2000年 | 41篇 |
1999年 | 84篇 |
1998年 | 356篇 |
1997年 | 235篇 |
1996年 | 168篇 |
1995年 | 97篇 |
1994年 | 96篇 |
1993年 | 89篇 |
1992年 | 42篇 |
1991年 | 34篇 |
1990年 | 27篇 |
1989年 | 48篇 |
1988年 | 38篇 |
1987年 | 34篇 |
1986年 | 27篇 |
1985年 | 23篇 |
1984年 | 20篇 |
1983年 | 20篇 |
1982年 | 32篇 |
1981年 | 38篇 |
1980年 | 33篇 |
1979年 | 21篇 |
1978年 | 18篇 |
1977年 | 65篇 |
1976年 | 88篇 |
1974年 | 15篇 |
1973年 | 24篇 |
排序方式: 共有3531条查询结果,搜索用时 15 毫秒
1.
2.
Patel Sapna Kumar Dushyant Chaurasiya Nitesh Kumar Tripathi Shweta 《Semiconductors》2019,53(13):1797-1803
Semiconductors - In the present paper, analytical modeling of surface potential and drain current for hetero-dielectric double gate tunnel FET (HDG-TFET) has been done. The two dimensional (2D)... 相似文献
3.
Journal of Mechanical Science and Technology - An experimental study is performed to explore the effect of swirl and number of swirler vanes on combustion characteristics of methane inverse... 相似文献
4.
Parsania P. H. Sankhavara Dharmesh B. Chopda Jalpa Patel Jignesh P. 《Polymer Bulletin》2020,77(6):3111-3128
Polymer Bulletin - Jute and glass composites of epoxy resin of (2E, 6E)-bis(4-hydroxybenzylidene)cyclohexanone (EBHBC) were prepared by compressing molding technique using three different hardeners... 相似文献
5.
全流程低功耗设计技术的应用 总被引:1,自引:0,他引:1
SameerPatel 《电子设计应用》2004,(1):91-92
随着便携式电子设备的日益使用,要求集成电路IC及SoC的功耗越来越低。在今后日益复杂的设计中,实现一个可靠的电源网络以减小功耗变成了主要的挑战。对于使用者来说,期待每一代新产品都具有新型功能,同时也希望产品的体积小并具有较长的工作时间。解决这个难题的方法之一就是采用新型的IC设计技术,以提供小而且高效的晶体管。在整个设计流程中,为了使器件的性能和可靠性最优,电源方面的限制非常关键。例如在逻辑门应用中,由于开关从一种状态转换到另一种状态从而引起动态功耗。在开关的转换过程中,和晶体管门极相连的所有内部电容将会被… 相似文献
6.
Systemic lupus erythematosus (SLE) is a multisystem organ disease, and involvement of the gastrointestinal system is relatively rare. We describe a 13-year-old girl who presented initially with abdominal pain, diarrhea, edema, and hypoalbuminemia. She was diagnosed with protein losing enteropathy (PLE) based on the significant increase of alpha 1-antitrypsin clearance in the stool. Two weeks after admission she developed clinical and serological findings that fulfilled the ACR criteria for SLE. Over 22 cases of lupus associated PLE have now been reported, but only 3 in children. Children with PLE should be evaluated for SLE. In addition, PLE should be suspected as a possible cause of unexplained edema and/or hypoalbuminemia in SLE. 相似文献
7.
GN Mozhokina GB Sokolova OV Makarova LP Mikha?lova 《Canadian Metallurgical Quarterly》1996,41(7-8):31-33
The effect of lomefloxacin was studied on mice with experimental infection due to Mycobacterium tuberculosis. The antibiotic was administered in doses of 100 and 200 mg/kg. It was shown that the use of lomefloxacin for a month provided a lower death rate of the animals with progressing acute generalized tuberculosis, a lower level of the lesions in the internal organs and a lower number of the Mycobacterium isolates from them. The efficacy of the treatment depended on the drug dose. When lomefloxacin was used in a dose of 200 mg/kg, the survival rate was much higher and the number of the epithelial unicellular granulomas in the tissue of the lung and spleen was markedly decreased while with the lower dose the indices did not differ from those in the control. 相似文献
8.
S Moss B Ibbotson H Prosser D Goldberg P Patel N Simpson 《Canadian Metallurgical Quarterly》1997,32(6):344-354
The Psychiatric Assessment Schedule for Adults with Developmental Disability (PAS-ADD) is a semi-structured interview for use with respondents who have learning disability and for key informants. This report investigates the ability of the instrument to detect symptoms that had been found to exist during routine clinical assessment of the patients. Field trials involved 95 referred patients with learning disability and a key informant for each sample member. Clinical opinions of the referring psychiatrists were sought using a symptom checklist. Referrer checklist symptoms and PAS-ADD data were both factor analysed. Validity testing involved (a) computation of correlations between PAS-ADD factors and checklist data and (b) comparison of PAS-ADD and referrers' diagnoses. Results indicated good validity for the PAS-ADD in relation to psychotic symptoms and depressive symptoms. Anxiety symptom identification was not well validated, probably due to small numbers. Expansive mood identified by the referrers was not detected by the PAS-ADD because there is currently no corresponding section in the interview. Where the PAS-ADD produced a diagnosis (in 58 members of the sample), 44 were in agreement with the referrer. Probability of diagnosis by PAS-ADD increased with the number of relevant active symptoms identified by the referrer. The PAS-ADD has been shown in a previous report to have the sensitivity to detect mental disorders not known to psychiatric services. For psychotic and depressive conditions, our results showed that symptom detection was in good agreement with the information provided by the referring psychiatrists on their patients. The PAS-ADD needs a section on hypomania and further investigation of its detection of anxiety disorders. 相似文献
9.
Three sporulation-specific genes (orfA, sigE, sigG) from clostridium acetobutylicum ATCC 824 are arranged in a cluster, encoding the putative sigma E-processing enzyme, sigma E, and sigma sigma G respectively. When they were transformed into Clostridium acetobutylicum while on a plasmid functional in this organism, transformants did not survive. Three kinds of recombinations were then attempted with nonreplicative plasmids: duplication of orfA and sigE, replacement of all of the three genes, and inactivation of orfA. While the wild-type strain ceased to grow and produce solvents in batch cultures after approximately 24 h, mutant strains were isolated that showed sustained growth for a much longer time and produced a threefold increase in acetone and butanol in test tube cultures. In addition, one of the derived strains showed a significantly higher growth rate. Features of the restriction maps of the recombinants did not correlate with expected maps, indicating possible complications occurring during the recombination events. 相似文献
10.
M.R. Kermani R.V. Patel M. Moallem 《Mechatronics, IEEE/ASME Transactions on》2005,10(2):181-188
In this paper, the application of high control authority piezostack actuators (PSAs) for active vibration control of large-scale flexible structures is studied. The idea is to add PSAs at appropriate locations of a flexible structure in order to strengthen its stiffness characteristics. In this regard, a flexible link of a macro-micro manipulator system actuated with PSAs is considered. The design of a mechanism for converting the force produced by a PSA to a bending moment is presented and a model for a system consisting of a flexible beam and a PSA is obtained. To this end, the solution of the governing partial differential equation with nonhomogeneous boundary conditions is obtained. Using singular value decomposition of the controllability Grammian of the system, optimum values for actuator parameters are obtained. The experimental results confirm that the suggested method can open up new possibilities in active vibration control of large-scale structures that require a large amount of control authority. 相似文献