全文获取类型
收费全文 | 1994篇 |
免费 | 49篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 139篇 |
综合类 | 5篇 |
化学工业 | 480篇 |
金属工艺 | 60篇 |
机械仪表 | 37篇 |
建筑科学 | 52篇 |
矿业工程 | 1篇 |
能源动力 | 69篇 |
轻工业 | 95篇 |
水利工程 | 26篇 |
石油天然气 | 1篇 |
无线电 | 173篇 |
一般工业技术 | 311篇 |
冶金工业 | 396篇 |
原子能技术 | 41篇 |
自动化技术 | 161篇 |
出版年
2023年 | 7篇 |
2022年 | 14篇 |
2021年 | 26篇 |
2020年 | 17篇 |
2019年 | 20篇 |
2018年 | 18篇 |
2017年 | 17篇 |
2016年 | 24篇 |
2015年 | 28篇 |
2014年 | 34篇 |
2013年 | 82篇 |
2012年 | 68篇 |
2011年 | 92篇 |
2010年 | 61篇 |
2009年 | 100篇 |
2008年 | 82篇 |
2007年 | 74篇 |
2006年 | 71篇 |
2005年 | 77篇 |
2004年 | 75篇 |
2003年 | 67篇 |
2002年 | 51篇 |
2001年 | 47篇 |
2000年 | 58篇 |
1999年 | 56篇 |
1998年 | 146篇 |
1997年 | 118篇 |
1996年 | 64篇 |
1995年 | 51篇 |
1994年 | 39篇 |
1993年 | 32篇 |
1992年 | 27篇 |
1991年 | 26篇 |
1990年 | 11篇 |
1989年 | 22篇 |
1988年 | 21篇 |
1987年 | 13篇 |
1986年 | 16篇 |
1985年 | 17篇 |
1984年 | 18篇 |
1983年 | 20篇 |
1982年 | 15篇 |
1981年 | 16篇 |
1980年 | 14篇 |
1979年 | 10篇 |
1978年 | 10篇 |
1977年 | 11篇 |
1976年 | 22篇 |
1973年 | 6篇 |
1972年 | 10篇 |
排序方式: 共有2047条查询结果,搜索用时 46 毫秒
1.
Joji Harada 《国际水资源开发杂志》2002,18(4):595-610
This paper discusses environmental conservation in reservoir watersheds, an important aspect relating to dam construction. The discussion of the subject describes how, in response to today's growing awareness of environmental issues, measures to absolutely minimize the effects on the environment of a dam project that will submerge the natural environment should be included in initial project plans, and how special concern for the environment ought to be shown throughout project implementation. Details are explained by introducing examples encountered in Japan. 相似文献
2.
3.
Shingo Hirano Akio Kawabata Masaru Yoshinaka Ken Hirota Osamu Yamaguchi 《Journal of the American Ceramic Society》1995,78(5):1414-1416
A compound denoted as (Ce0.75 Zr0.25 )O2 (Ce, ZrO8 ) is formed near room temperature from cerium and zirconium nitrates using hydrazine monohydrate. It has a cubic unit cell with a = 0.5342 nm. Characterization of powders heated to various temperatures at 10°C/min demonstrates that the specific surface area does not decrease below 20 mVg until >1000°C. 相似文献
4.
Motofumi Suzuki Kohei Kinoshita Shinji Jomori Hidehiko Harada Kaoru Nakajima Kenji Kimura 《Thin solid films》2007,515(22):8281-8284
The initial stage of iron silicide formation is investigated by high-resolution Rutherford backscattering spectroscopy. During the Fe deposition on Si(001) at 470 °C, the formation of FeSi2 is confirmed by the surface peak analysis. Initially, FeSi2 grows epitaxially so that one of the major crystallographic axes is parallel to the <111> axis of the Si substrate. With increasing Fe deposition, the deviation between the major crystallographic axis of the silicide region and Si<111> increases although the electron diffraction pattern is independent of the amount of Fe deposition. Therefore, the subsurface crystallographic structure of iron silicide is transformed from a cubic-like to a low-symmetry structure. 相似文献
5.
Masaru Kadoshima Masahiko HirataniYasuhiro Shimamoto Kazuyoshi ToriiHiroshi Miki Shinichiro KimuraToshihide Nabatame 《Thin solid films》2003,424(2):224-228
We investigated rutile-type titanium dioxide (TiO2) films for possible use as a high-k gate insulator. The TiO2 thin films were directly deposited on Si substrates using a RF magnetron sputtering method with a sintered oxide target. A single phase of rutile-type TiO2 whose dielectric constant of approximately 75 was obtained when the film was deposited in an inert gas atmosphere and annealed at 800 °C in an oxidizing gas atmosphere. The oxygen ions were deficient in the as-deposited film, and consequently, a sufficient oxygen supply was needed to crystallize the film to a single phase of rutile during the post-annealing. However, the interfacial SiO2 layer between the TiO2 and the Si substrate simultaneously grew thicker than 2 nm. As the interfacial SiO2 grew, the leakage current was decreased and the equivalent oxide thickness was increased, in the Au/rutile-type TiO2/Si capacitor. Therefore, we concluded that the growth of the interfacial SiO2 layer thicker than 2 nm is inevitable to form the single phase of rutile-type TiO2 and to decrease the leakage. 相似文献
6.
Data fitting with a spline using a real-coded genetic algorithm 总被引:2,自引:0,他引:2
Fujiichi Yoshimoto Author Vitae Toshinobu Harada Author Vitae Author Vitae 《Computer aided design》2003,35(8):751-760
To obtain a good approximation for data fitting with a spline, frequently we have to deal with knots as variables. The problem to be solved then becomes a continuous nonlinear and multivariate optimization problem with many local optima. Therefore, it is difficult to obtain the global optimum. In this paper, we propose a method for solving this problem by using a real-coded genetic algorithm. Our method can treat not only data with a smooth underlying function, but also data with an underlying function having discontinuous points and/or cusps. We search for the best model among candidate models by using the Bayes Information Criterion (BIC). With this, we can appropriately determine the number and locations of knots automatically and simultaneously. Five examples of data fitting are given to show the performance of our method. 相似文献
7.
8.
9.
Changes in the brain lactate concentration in cerebral extracellular fluid (ECF) during intravenous infusion of glucose and local administration of glucose were investigated in adult, conscious, unrestrained rats, with a microdialysis probe in the posterior hippocampus. The rats were infused intravenously with either 25% sucrose solution or 25% glucose solution at a rate of 16.6 microliters.min-1.100 g-1 for three hours. The blood glucose concentration reached 17.0 +/- 2.6 mM at the end of the glucose infusion, and brain ECF glucose showed a parallel change with the blood glucose concentration and increased to 2.37 +/- 0.30 mM. However, blood and brain ECF glucose concentrations did not change in animals infused with the sucrose solution. On the other hand, the blood lactate concentration in the glucose-infused group also increased from 0.93 +/- 0.18 mM to 2.85 +/- 0.39 mM at the end of the glucose infusion, which was significantly higher than that measured in the sucrose-infused group. The blood lactate level in the glucose-infused group returned to the basal level by the end of the experiment. Brain ECF lactate concentrations increased from 1.21 +/- 0.06 mM to 1.69 +/- 0.11 mM in glucose-infused animals, but did not change in the sucrose-infused animals. The brain ECF lactate concentration showed a positive correlation with the brain ECF glucose concentration in glucose-infused animals. Another group of rats was administered glucose locally for 90 min after substitution of artificial cerebrospinal fluid.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
10.