全文获取类型
收费全文 | 3469篇 |
免费 | 84篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 135篇 |
综合类 | 7篇 |
化学工业 | 723篇 |
金属工艺 | 73篇 |
机械仪表 | 56篇 |
建筑科学 | 65篇 |
矿业工程 | 2篇 |
能源动力 | 112篇 |
轻工业 | 257篇 |
水利工程 | 9篇 |
石油天然气 | 2篇 |
无线电 | 413篇 |
一般工业技术 | 476篇 |
冶金工业 | 900篇 |
原子能技术 | 51篇 |
自动化技术 | 274篇 |
出版年
2023年 | 21篇 |
2022年 | 42篇 |
2021年 | 72篇 |
2020年 | 24篇 |
2019年 | 35篇 |
2018年 | 54篇 |
2017年 | 45篇 |
2016年 | 56篇 |
2015年 | 44篇 |
2014年 | 81篇 |
2013年 | 133篇 |
2012年 | 126篇 |
2011年 | 139篇 |
2010年 | 109篇 |
2009年 | 122篇 |
2008年 | 139篇 |
2007年 | 114篇 |
2006年 | 89篇 |
2005年 | 111篇 |
2004年 | 74篇 |
2003年 | 93篇 |
2002年 | 78篇 |
2001年 | 77篇 |
2000年 | 67篇 |
1999年 | 83篇 |
1998年 | 370篇 |
1997年 | 207篇 |
1996年 | 134篇 |
1995年 | 94篇 |
1994年 | 89篇 |
1993年 | 81篇 |
1992年 | 35篇 |
1991年 | 37篇 |
1990年 | 31篇 |
1989年 | 47篇 |
1988年 | 26篇 |
1987年 | 23篇 |
1986年 | 30篇 |
1985年 | 25篇 |
1984年 | 27篇 |
1983年 | 25篇 |
1982年 | 20篇 |
1981年 | 27篇 |
1980年 | 20篇 |
1979年 | 24篇 |
1978年 | 25篇 |
1977年 | 30篇 |
1976年 | 47篇 |
1974年 | 14篇 |
1973年 | 9篇 |
排序方式: 共有3555条查询结果,搜索用时 15 毫秒
71.
72.
A. Bensalah Y. Guyot M. Ito A. Brenier H. Sato T. Fukuda G. Boulon 《Optical Materials》2004,26(4):375
YLiF4 (YLF) single crystals undoped and Yb3+-doped with different concentrations were grown by the Czochralski technique under CF4 atmosphere. Detailed analysis of Yb3+-doped YLF spectroscopy were made to contribute to the determination of energy levels in this host. We are dealing with temperature and concentration dependences of both π and σ polarizations of the infrared (IR) absorption and emission spectra. Raman spectra were also used to give an attempt of interpretation of electronic and vibronic levels. The radiative energy transfer (self-trapping) and strong phonon–electron coupling make the assignment of Yb3+ energy levels difficult. Evaluation of the laser potentiality of this fluoride host is also presented. 相似文献
73.
A. Yoshikawa C. Fujiwara H. Sato T. Nishi H. Ohta T. Fukuda Y. Waseda G. Boulon M. Ito Y. Guyot K. Lebbou 《Optical Materials》2004,26(4):385
Ca8(La,Yb)2(PO4)6O2 (Yb:CLPA) single crystals with the apatite-type structure could be grown from the melt using the Czochralski method. Grown crystal was 18 mm in diameter and 110 mm in length. It is transparent with slightly blue color. Neither visible inclusion nor crack was observed. Thermal conductivity of Yb:CLPA was calculated from the values of thermal diffusivity, heat capacity measurement and density. Luminescent characterization was carried out from the results of emission, absorption and Raman spectrum. 相似文献
74.
M Fujita K Nomura K Hong Y Ito A Asada S Nishimuro 《Canadian Metallurgical Quarterly》1993,197(3):1340-1347
A strong fibrinolytic enzyme (nattokinase) was purified from the vegetable cheese natto. Nattokinase was extracted from natto with saline and isolated by sequential use of hydrophobic chromatography on Butyl-Toyopearl, ion-exchange chromatography on CM-Toyopearl, and gel-filtration on Sephadex G-50. The isolated protein gave a single sharp band on SDS-PAGE either before or after reduction. The sequence, as determined by automated Edman degradation of the uncleaved molecule and its enzymatically derived peptide, consisted of a total 275 amino acid residues (M.W = 27,728) and exhibited a high homology with the subtilisins. The purified nattokinase digested not only fibrin but also several synthetic substrates. Among the synthetic substrates, the most sensitive substrate was Suc-Ala-Ala-Pro-Phe-pNA for subtilisin. PMSF inhibited both the fibrinolytic activity and the amidolytic activity. The results indicate that nattokinase is a subtilisin-like serine protease. 相似文献
75.
T Oki T Tabata H Yamada T Wakatsuki Y Mishiro M Abe Y Onose A Iuchi S Ito 《Canadian Metallurgical Quarterly》1998,11(12):1106-1112
Examination of left ventricular (LV) diastolic dysfunction in hypertensive patients has been based on parameters obtained from the transmitral flow velocity during pulsed Doppler echocardiography. However, these parameters are affected by loading conditions. We evaluated LV diastolic function along the longitudinal and transverse axes by pulsed tissue Doppler imaging (TDI) in 50 hypertensive (HT) patients and 36 age-matched healthy volunteers (N). Transmitral flow velocity was recorded by pulsed Doppler echocardiography. LV posterior wall motion velocity along the longitudinal and transverse axes also was recorded by pulsed TDI. In both groups, peak early diastolic velocity of the LV posterior wall (Ew) along the transverse axis (N: 15.8+/-5.2 cm/s, HT: 12.2+/-4.4 cm/s) was higher than that along the longitudinal axis (N: 12.7+/-3.1 cm/s, HT: 9.5+/-3.3 cm/s). Peak atrial systolic velocity of the LV posterior wall (Aw) along the longitudinal axis (N: 9.1+/-1.8 cm/s, HT: 9.7 +/-2.6 cm/s) significantly exceeded that along the transverse axis (N: 8.0+/-2.2 cm/s, HT: 8.4+/-2.4 cm/s) in both groups. The Ews were lower and the Aws were higher along both axes in the patient group than in the control group. The time intervals from the aortic component of the second heart sound to the peak of the early diastolic wave (IIA-Ews) along both the transverse (N: 142+/-18 ms, HT: 154+/-19 ms) and longitudinal (N: 151 16 ms, HT: 162+/-20 ms) axes were longer in the patient group. In 29 patients, Ews along both axes correlated negatively (transverse: r = -0.80, P < .0001; longitudinal: r = -0.71, P < .0001) and IIA-Ews correlated positively (transverse: r = 0.81, P < .0001; longitudinal: r = 0.74, P < .001) with the time constant of the LV pressure decay during isovolumic diastole. The Aws along both axes in the 24 patients without pseudonormalization in transmitral flow velocity correlated positively (transverse: r = 0.60, P < .001; longitudinal: r = 0.74, P < .0001) with the LV end-diastolic pressure. In conclusion, LV relaxation and filling along the longitudinal and transverse axes were impaired in many patients with hypertension. Pulsed TDI was useful for evaluating LV diastolic dynamics in this disease. 相似文献
76.
Yoshimi Ito 《Robotics and Computer》1987,3(3)
The evaluation of FMS becomes very important in accordance with the advancement of FMS technology. The evaluation method so far employed is the economical justification; however, it should be improved so as to enable the system flexibility to be simultaneously evaluated. Thus, this paper describes the reviewed results on the present trend of system evaluation, putting the main stress on the technology regarding the evaluation of system flexibility. 相似文献
77.
Hirono Kaneyasu Keita Kishigi Yasumasa Hasegawa 《Journal of Low Temperature Physics》2006,142(3-4):469-472
We have measured the electrical resistivities and magnetoresistances (MR) of (EDT-DSDTFVO)2X (X=FeCl4, GaCl4), where EDT-DSDTFVO stands for ethylenedithiodiselenadithiafulvalenothioquinone-1,3-dithiolemethide. These materials undergo
gradual metal-insulator transitions at Tmin=52 K for FeCl4-salt and Tmin=30 K for GaCl4-salt, respectively. In spite of the similarity of the temperature dependence of the resistivity and its pressure effect,
MR of both salts exhibit a clear contrast, i.e. FeCl4-salt shows negative and GaCl4, positive. Origin of the difference in the sign of MR between these salts are discussed in terms of the existence of π-d
interaction. 相似文献
78.
Xiaoyu Li Masahiko Ito Haruyo Aoyagi Asako Murayama Hideki Aizaki Masayoshi Fukasawa Takanobu Kato Takaji Wakita Tetsuro Suzuki 《International journal of molecular sciences》2022,23(15)
In microbiological research, it is important to understand the time course of each step in a pathogen’s lifecycle and changes in the host cell environment induced by infection. This study is the first to develop a real-time monitoring system that kinetically detects luminescence reporter activity over time without sampling cells or culture supernatants for analyzing the virus replication. Subgenomic replicon experiments with hepatitis C virus (HCV) showed that transient translation and genome replication can be detected separately, with the first peak of translation observed at 3–4 h and replication beginning around 20 h after viral RNA introduction into cells. From the bioluminescence data set measured every 30 min (48 measurements per day), the initial rates of translation and replication were calculated, and their capacity levels were expressed as the sums of the measured signals in each process, which correspond to the areas on the kinetics graphs. The comparison of various HuH-7-derived cell lines showed that the bioluminescence profile differs among cell lines, suggesting that both translation and replication capacities potentially influence differences in HCV susceptibility. The effects of RNA mutations within the 5′ UTR of the replicon on viral translation and replication were further analyzed in the system developed, confirming that mutations to the miR-122 binding sites primarily reduce replication activity rather than translation. The newly developed real-time monitoring system should be applied to the studies of various viruses and contribute to the analysis of transitions and progression of each process of their life cycle. 相似文献
79.
Huiyuan Geng Takahiro Ochi Shogo Suzuki Masaaki Kikuchi Satoru Ito Junqing Guo 《Journal of Electronic Materials》2013,42(7):1999-2005
Bulk multifilled n- and p-type skutterudites with La as the main filler were fabricated using the spark plasma sintering (SPS) method. The thermoelectric properties and thermal stability of these skutterudites were investigated. It was found that the interactions among the filling atoms also play a vital role in reducing the lattice thermal conductivity of the multifilled skutterudites. ZT = 0.76 for p-type La0.8Ba0.01Ga0.1Ti0.1Fe3CoSb12 and ZT = 1.0 for n-type La0.3Ca0.1Al0.1Ga0.1In0.2Co3.75Fe0.25Sb12 skutterudites have been achieved. Furthermore, the differential scanning calorimetry (DSC) results show that there is no skutterudite phase decomposition till 750°C for the La0.8Ba0.01Ga0.1Ti0.1Fe3CoSb12 sample. The thermal stability of the La0.8Ba0.01Ga0.1Ti0.1Fe3CoSb12 skutterudite is greatly improved. Using the developed multifilled skutterudites, the fabricated module with size of 50 mm × 50 mm × 7.6 mm possesses maximum output power of 32 W under the condition of hot/cold sides = 600°C/50°C. 相似文献
80.
Riku Kawasaki Kosuke Kondo Risako Miura Keita Yamana Hinata Isozaki Risako Shimada Shogo Kawamura Hidetoshi Hirano Tomoki Nishimura Naoki Tarutani Kiyofumi Katagiri Alexandra Stubelius Shin-ichi Sawada Yoshihiro Sasaki Kazunari Akiyoshi Atsushi Ikeda 《International journal of molecular sciences》2022,23(9)
Developing photoactivatable theranostic platforms with integrated functionalities of biocompatibility, targeting, imaging contrast, and therapy is a promising approach for cancer diagnosis and therapy. Here, we report a theranostic agent based on a hybrid nanoparticle comprising fullerene nanocrystals and gold nanoparticles (FGNPs) for photoacoustic imaging and photothermal therapy. Compared to gold nanoparticles and fullerene crystals, FGNPs exhibited stronger photoacoustic signals and photothermal heating characteristics by irradiating light with an optimal wavelength. Our studies demonstrated that FGNPs could kill cancer cells due to their photothermal heating characteristics in vitro. Moreover, FGNPs that are accumulated in tumor tissue via the enhanced permeation and retention effect can visualize tumor tissue due to their photoacoustic signal in tumor xenograft model mice. The theranostic agent with FGNPs shows promise for cancer therapy. 相似文献