全文获取类型
收费全文 | 1124篇 |
免费 | 29篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 64篇 |
综合类 | 2篇 |
化学工业 | 293篇 |
金属工艺 | 44篇 |
机械仪表 | 37篇 |
建筑科学 | 14篇 |
能源动力 | 44篇 |
轻工业 | 62篇 |
水利工程 | 2篇 |
石油天然气 | 4篇 |
无线电 | 106篇 |
一般工业技术 | 168篇 |
冶金工业 | 206篇 |
原子能技术 | 48篇 |
自动化技术 | 64篇 |
出版年
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 9篇 |
2020年 | 7篇 |
2018年 | 12篇 |
2017年 | 11篇 |
2016年 | 27篇 |
2015年 | 24篇 |
2014年 | 19篇 |
2013年 | 44篇 |
2012年 | 21篇 |
2011年 | 52篇 |
2010年 | 30篇 |
2009年 | 39篇 |
2008年 | 53篇 |
2007年 | 40篇 |
2006年 | 49篇 |
2005年 | 29篇 |
2004年 | 31篇 |
2003年 | 60篇 |
2002年 | 29篇 |
2001年 | 31篇 |
2000年 | 23篇 |
1999年 | 25篇 |
1998年 | 93篇 |
1997年 | 50篇 |
1996年 | 51篇 |
1995年 | 23篇 |
1994年 | 21篇 |
1993年 | 26篇 |
1992年 | 19篇 |
1991年 | 11篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 11篇 |
1987年 | 13篇 |
1986年 | 15篇 |
1985年 | 15篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1981年 | 14篇 |
1980年 | 10篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1977年 | 13篇 |
1976年 | 16篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 5篇 |
排序方式: 共有1158条查询结果,搜索用时 15 毫秒
971.
Keiji Ishibashi Minoru Karasawa Ge Xu Naoaki Yokokawa Manabu Ikemoto Atsushi Masuda Hideki Matsumura 《Thin solid films》2003,430(1-2):58-62
Thin film deposition on large-area substrates of 1-m size is demonstrated by catalytic chemical vapor deposition (Cat-CVD) apparatus equipped with a newly developed showerhead catalyzer unit. The arrangement of catalyzer wires for uniform film thickness was determined by simulation, assuming that decomposed species on catalyzers were transported by isotropic thermal diffusion without an influence of the gas flow. A film thickness uniformity of ±7.5% was successfully achieved on a substrate of 400 mm×960 mm at an average deposition rate of 32 nm/min for hydrogenated amorphous silicon (a-Si:H) film. Film thickness uniformity of ±8.6% for a-Si:H film and ±12.3% for silicon nitride film were also successfully obtained on substrates of 680 mm×880 mm size at an average deposition rate of 12.1 and 2.5 nm/min, respectively. These results suggest that Cat-CVD is a promising method for the fabrication of large-area devices such as thin-film-transistor liquid-crystal displays and solar cells. 相似文献
972.
973.
T Sasaki H Yamada K Matsumura T Shimizu A Kobata T Endo 《Canadian Metallurgical Quarterly》1998,1425(3):599-606
We assessed the importance of lean and fat tissue depletion as determinants of the adaptive reduction in basal metabolic rate (BMR) in response to food deprivation by reanalyzing the data on BMR and body composition for the 32 men participating in the classic Minnesota experiment of semi-starvation and refeeding. We used individual data on BMR, body fat, and fat-free mass (FFM) assessed during the control (prestarvation) period, at weeks 12 and 24 of semistarvation (S12 and S24), and week 12 of restricted refeeding (R 12) to calculate an index of the reduction in thermogenesis at S12, S24, and R12, defined as the change in BMR adjusted for changes in FFM and fat mass, and an index of the state of depletion of the fat mass and FFM compartments at these times, defined as the deviation in fat mass or FFM relative to control values. The results indicated a positive relation between the reduction in thermogenesis and the degree of fat mass depletion (but not FFM depletion) during weight loss as well as during weight recovery (r = 0.5, P < 0.01). Furthermore, the residual variance was predicted by the initial (prestarvation) percentage fat and the cormic index (sitting height/height). Taken together, these results in normal-weight men responding to severe food deprivation reveal anthropometric predictors for human interindividual variability in the capacity for energy conservation and suggest that the adaptive reduction in BMR is partly determined by an autoregulatory feedback control system linking the state of depletion of fat stores to compensatory mechanisms that suppress thermogenesis. 相似文献
974.
975.
Most screws used in fracture fixation necessitate a separate step for tapping of the screw hole. Titanium screw systems have been developed in which the screws can be inserted directly after a drill hole is made. These self-tapping screws thereby eliminate an operative step. A retrospective study was conducted that evaluated all wrist and hand procedures performed between January 1992 and December 1994 by 1 surgeon using screw fixation. The results of 39 cases treated with standard tapped titanium screws were compared with 28 cases treated with self-tapping titanium screws. Nearly identical union and complication rates were obtained in each group. Comparable results can be obtained with self-tapping screw fixation, which limits the number of instruments needed, eliminates an operative step, and thereby may diminish operative risk and shorten operative time. 相似文献
976.
Tsutomu Hozumi Akio Saito Seiji Okawa Takayoshi Matsumura 《International Journal of Refrigeration》2002,25(2)
In order to clarify effects of bubble nuclei on freezing of supercooled water, various kinds of experiments were carried out with invisible sizes of bubbles in supercooled water. Water samples were kept in a test tube and cooled down at a constant cooling rate until the water solidified. The degree of supercooling at freezing was then measured. Two kinds of water surfaces were applied. One was exposure to the atmosphere, and the other was covered with silicone oil. Three kinds of pressure conditions were applied. The first type was atmospheric pressure. The second type was compression up to 6.0 atm. The third type was evacuated down to 0.02 atm. Two holding time periods before starting the experiments were applied. One was 30 min and the other was 24 h. It was found that the degree of supercooling at freezing is high in the case of the free surface compared to the one with oil–water surface. The reason suggested was that the bubbles in the water can be released from the surface in the case of normal atmospheric exposure and trapped at the oil–water interface in the case of water covered with oil. Hence, it was clarified that the freezing of supercooled water is affected by the existence of bubble nuclei. 相似文献
977.
Muthusamy Sivakumar Yusuke Yamamoto Devaraj Amutharani Yoshiharu Tsujita Hiroaki Yoshimizu Takatoshi Kinoshita 《应用聚合物科学杂志》2003,89(11):2882-2887
Syndiotactic polystyrene (sPS) membranes containing different mole fractions of p‐xylene were prepared by a solution‐casting procedure. Complex formation between sPS and xylene was studied by thermogravimetric analysis and Fourier transform infrared spectroscopy. The stability and desorption behavior of the sPS–guest solvent and phase transitions were studied by differential scanning calorimetry. The formation of the δ‐form complex in the presence of different mole fractions of xylene isomers was analyzed and confirmed. The mole fraction of p‐xylene in the dried membrane was found to be higher than that of the corresponding mole fraction in the isomer solvent solution used for casting. This was attributed to the preferential complexing ability of p‐xylene with sPS. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2882–2887, 2003 相似文献
978.
Crystallization by excimer laser annealing for a-Si:H films with low hydrogen content prepared by Cat-CVD 总被引:1,自引:0,他引:1
Crystallization by excimer-laser annealing (ELA) for hydrogenated amorphous silicon (a-Si:H) films with low hydrogen content (CH) prepared by catalytic chemical vapor deposition (Cat-CVD) was systematically studied. From optical microscopy images, no hydrogen bubbling was observed during ELA, even without a dehydrogenation process. As the laser energy density was increased to 300 mJ cm−2, the full width at half-maximum of the Raman signal from the crystalline phase decreased to approximately 4 cm−1. This value is almost equal to or even smaller than that reported for polycrystalline Si (poly-Si) films prepared from plasma-enhanced CVD (PECVD) a-Si:H films by ELA so far. The average grain size, estimated from scanning electron microscopy, was approximately 500 nm for CH of 1.3 at.%. On the other hand, the grain size of poly-Si films prepared from PECVD a-Si:H films with a dehydrogenation process was only 200 nm. The technique using Cat-CVD films is expected to be used for fabrication of low-temperature high-mobility thin-film transistors. 相似文献
979.
Daisuke Iioka Hirotaka Shimizu Yasunobu Yokomizu Masuo Goto Toshiro Matsumura 《Electrical Engineering in Japan》2004,148(3):15-24
In this paper, it was assumed that a synchronous generator in a customer system was connected to a distribution system via the fault current limiter (FCL). We theoretically investigated the influence of the output power of the generator on the limiting effect of the fault current when a three‐phase short‐circuit fault occurs. It was shown that the fault current out of the customer system, limited by the FCL, rises with the output power of the generator. It was found that the larger the output, the higher the fault current at the fault point is when the limiting resistance is less than 15 Ω in the case of the resistive‐type FCL. On the other hand, the fault current at the fault point decreases with an increase in the output power for a limiting resistance more than 15 Ω. In contrast, it was found that the suppressing effect on the fault current at the fault point due to the inductive‐type FCL hardly depends on the output power. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(3): 15–24, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10357 相似文献
980.
The natural polyamines putrescine, spermidine and spermine are intimately involved in growth-related processes. More and more evidence indicates that the excessive accumulation of putrescine and spermidine favors malignant transformation of cells. Selective depletion of putrescine has been shown to restore in some transformed cells the normal phenotype. Inhibition of polyamine formation appears, therefore, a rational target in chemoprevention. Clinical trials with 2-(difluoromethyl)ornithine, a selective inactivator of ornithine decarboxylase, a key enzyme of polyamine biosynthesis, are promising. Structural analogs of the polyamines with polyamine-mimetic or antagonist properties, and calmodulin antagonists are other types of drugs which affect several key reactions of polyamine metabolism, and appear to be candidates for the prevention of carcinogenesis especially of the gastrointestinal tract. 相似文献