全文获取类型
收费全文 | 1664篇 |
免费 | 9篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 11篇 |
综合类 | 7篇 |
化学工业 | 181篇 |
金属工艺 | 8篇 |
机械仪表 | 74篇 |
建筑科学 | 120篇 |
矿业工程 | 13篇 |
能源动力 | 5篇 |
轻工业 | 294篇 |
水利工程 | 42篇 |
石油天然气 | 21篇 |
无线电 | 69篇 |
一般工业技术 | 743篇 |
冶金工业 | 10篇 |
原子能技术 | 3篇 |
自动化技术 | 80篇 |
出版年
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 10篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 5篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 12篇 |
2013年 | 1篇 |
2012年 | 165篇 |
2011年 | 292篇 |
2010年 | 65篇 |
2009年 | 31篇 |
2008年 | 186篇 |
2007年 | 146篇 |
2006年 | 138篇 |
2005年 | 91篇 |
2004年 | 87篇 |
2003年 | 77篇 |
2002年 | 47篇 |
2001年 | 57篇 |
2000年 | 37篇 |
1999年 | 19篇 |
1998年 | 21篇 |
1997年 | 13篇 |
1996年 | 17篇 |
1995年 | 18篇 |
1994年 | 17篇 |
1993年 | 19篇 |
1992年 | 15篇 |
1991年 | 7篇 |
1990年 | 15篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1967年 | 3篇 |
1958年 | 2篇 |
1955年 | 1篇 |
排序方式: 共有1681条查询结果,搜索用时 31 毫秒
11.
目前,在高性能和一般用途的注射成型机中普遍采用的锁模机构是双曲肘机械式锁模机构。但是注射成型厂家对双曲肘锁模机构如此广泛使用的特点——高速、性能稳定及结构牢固——常为单曲肘锁模机构所超越而感到惊奇。 相似文献
12.
The application of supercritical fluid chromatography (SFC) coupled with a UV variable-wavelength detector to isolate the
minor components (carotenes, vitamin E, sterols, and squalene) in crude palm oil (CPO) and the residual oil from palm-pressed
fiber is reported. SFC is a good technique for the isolation and analysis of these compounds from the sources mentioned. The
carotenes, vitamin E, sterols, and squalene were isolated in less than 20 min. The individual vitamin E isomers present in
palm oil were also isolated into their respective components, α-tocopherol, α-tocotrienol, γ-tocopherol, γ-tocotrienol, and
δ-tocotrienol. Calibration of all the minor components of palm as well as the individual components of palm vitamin E was
carried out and was found to be comparable to those analyzed by other established analytical methods. 相似文献
13.
14.
Clausen CH Dimaki M Panagos SP Kasotakis E Mitraki A Svendsen WE Castillo-León J 《Scanning》2011,33(4):201-207
In this report electrostatic force microscopy (EFM) is used to study different peptide self-assembled structures such as tubes and particles. It is shown that not only geometrical information can be obtained using EFM, but also information about the composition of different structures. In particular we use EFM to investigate the structures of diphenylalanine peptide tubes, particles, and CSGAITIG peptide particles placed on pre-fabricated SiO(2) surfaces with a backgate. We show that the cavity in the peptide tubes could be due to the presence of water residues. Additionally we show that self-assembled amyloid peptides form spherical solid structures containing the same self-assembled peptide in its interior. In both cases transmission electron microscopy is used to verify these structures. Further, the limitations of the EFM technique are discussed, especially when the observed structures become small compared with the radius of the AFM tip used. Finally, an agreement between the detected signal and the structure of the hollow peptide tubes is demonstrated. 相似文献
15.
Lee GC Kim YS Kim MJ Oh SA Choi I Choi J Park JG Chong CK Kim YY Lee K Lee CH 《Water science and technology》2011,63(11):2745-2751
The unpleasant odor of drinking water is one of the major problems in many water utilities in the world. Actinomycetes have long been associated with odorous compounds. Considering the paucity of research on Actinomycetes producing odorous compounds in South Korea, presence of Actinomycetes, their molecular characteristics and ability to produce odorous compounds were investigated in this study. Findings confirmed the presence of Actinomycetes in surface soil, sediment, and water samples from four sites: two artificial lakes [Paldang and Cheongpyeong (CP)], and two streams [Gyeongan (GA) and Yangpyeong]. Surface soil and sediment from CP area had the greatest concentration of Actinomycetes (8.2 x 10(7) and 6.8 x 10(6) colony forming units (CFUs)/gram, dry weight, respectively). When water samples are considered, samples from GA had the highest concentration (1.9 x 10(2) CFU/mL). 16S rRNA sequencing and molecular phylogenetic analysis showed that Streptomyces was the dominant genus (64.1%). In addition, the isolated Actinomycetes synthesized 5.4 ng/L geosmin as demonstrated by thermal desorption unit-gas chromatograph/mass spectrometry analysis. 相似文献
16.
This paper presents a Fuzzy Neural Network (FNN) control system for a traveling-wave ultrasonic motor (TWUSM) driven by a dual mode modulation non-resonant driving circuit. First, the motor configuration and the proposed driving circuit of a TWUSM are introduced. To drive a TWUSM effectively, a novel driving circuit, that simultaneously employs both the driving frequency and phase modulation control scheme, is proposed to provide two-phase balance voltage for a TWUSM. Since the dynamic characteristics and motor parameters of the TWUSM are highly nonlinear and time-varying, a FNN control system is therefore investigated to achieve high-precision speed control. The proposed FNN control system incorporates neuro-fuzzy control and the driving frequency and phase modulation to solve the problem of nonlinearities and variations. The proposed control system is digitally implemented by a low-cost digital signal processor based microcontroller, hence reducing the system hardware size and cost. The effectiveness of the proposed driving circuit and control system is verified with hardware experiments under the occurrence of uncertainties. In addition, the advantages of the proposed control scheme are indicated in comparison with a conventional proportional-integral control system. 相似文献
17.
Nanoporous polyimide films were prepared from triblock copolyimides. A thermally labile polymer, poly(propylene glycol), was incorporated into polyimides based on 4,4-(hexafluoroisopropylidene)diphthalic anhydride to obtain triblock copolyimides. Nanofoams were formed by thermolysis of the labile block. The thermal properties of the copolymers were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The nanopores were characterized by scanning electron microscopy (SEM). 相似文献
18.
19.
We have developed a diode laser apparatus to excite Li from its ground 2S state, through 2P and 3S, to its Rydberg states with three cw diode lasers operating at λ = 671 nm, 813 nm, and 630-635 nm. A He-Ne laser at λ = 633 is sometimes used in place of the 635-nm diode laser for the last step. The output power of each of these lasers was ~1 mW. We describe our technique of locking the first two lasers on Li resonance lines by obtaining a fluorescent signal from the second decay (3S ? 2P) that is normally overpowered by a strong background of fluorescent light from the first decay (2P ? 2S). We used two balanced photodiodes to reject the strong fluorescent light without loss of collection efficiency. A rejection ratio as high as 100 has been obtained. 相似文献
20.