全文获取类型
收费全文 | 1719篇 |
免费 | 32篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 82篇 |
综合类 | 2篇 |
化学工业 | 399篇 |
金属工艺 | 61篇 |
机械仪表 | 35篇 |
建筑科学 | 42篇 |
能源动力 | 81篇 |
轻工业 | 84篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 130篇 |
一般工业技术 | 313篇 |
冶金工业 | 371篇 |
原子能技术 | 64篇 |
自动化技术 | 93篇 |
出版年
2023年 | 6篇 |
2022年 | 14篇 |
2021年 | 28篇 |
2020年 | 13篇 |
2019年 | 17篇 |
2018年 | 21篇 |
2017年 | 15篇 |
2016年 | 17篇 |
2015年 | 17篇 |
2014年 | 35篇 |
2013年 | 68篇 |
2012年 | 49篇 |
2011年 | 55篇 |
2010年 | 53篇 |
2009年 | 63篇 |
2008年 | 77篇 |
2007年 | 76篇 |
2006年 | 48篇 |
2005年 | 49篇 |
2004年 | 47篇 |
2003年 | 66篇 |
2002年 | 49篇 |
2001年 | 54篇 |
2000年 | 34篇 |
1999年 | 46篇 |
1998年 | 149篇 |
1997年 | 88篇 |
1996年 | 70篇 |
1995年 | 54篇 |
1994年 | 59篇 |
1993年 | 53篇 |
1992年 | 16篇 |
1991年 | 22篇 |
1990年 | 27篇 |
1989年 | 29篇 |
1988年 | 17篇 |
1987年 | 20篇 |
1986年 | 9篇 |
1985年 | 10篇 |
1984年 | 16篇 |
1983年 | 14篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1977年 | 13篇 |
1976年 | 16篇 |
1975年 | 7篇 |
1973年 | 4篇 |
排序方式: 共有1763条查询结果,搜索用时 15 毫秒
201.
K Ozawa H Miura T Tamagawa Y Hiyoshi K Nonogaki N Maeda G Watanabe N Sakamoto A Iguchi 《Canadian Metallurgical Quarterly》1993,53(25):1903-1909
We investigated the effects of intrahypothalamic or hippocampal injection of GABA receptor agonists on hyperglycemia induced by hippocampal neostigmine. Prior to the injection of neostigmine (50 nmol) into the hippocampus (HPC), muscimol (0.01-1 nmol) or baclofen (1 nmol) was injected into the bilateral ventromedial hypothalamus (VMH). Muscimol suppressed the hyperglycemia in a dose-dependent manner, but baclofen affected it only minimally. In contrast, neither hippocampal muscimol (1 or 2.5 nmol) nor baclofen (1 nmol) suppressed the hippocampal neostigmine-dependent hyperglycemia. Intrahypothalamic muscimol (1 nmol) also decreased the changes in hepatic venous plasma glucagon and epinephrine significantly. These results indicate that intrahypothalamic muscimol suppresses hyperglycemia caused by cholinergic neurons originating from the HPC, indicating existence of the location specificity. 相似文献
202.
203.
The effect of magnetic and nonmagnetic annealing on the magnetic anisotropy in CoNbZr films, formed by a DC opposing-targets sputtering method, was investigated. It was revealed that the origin of the magnetic anisotropy is the directional ordering of the magnetic atoms. The anisotropy fields and the direction of the easy axis obtained when the films are annealed in zero magnetic field are almost the same as those for the magnetic field parallel to the easy axis of the as-deposited films. When the films are annealed in a magnetic field perpendicular to the easy axis, the anisotropy field induced in parallel with the magnetic field, H k(t ), is well represented by the following formula: ln {1-H k(t )/H k(∞)∝-√Tt , where H k(∞) is the thermal equilibrium value of the anisotropy field and D is the diffusion constant. The activation energy of the as-deposited film is 0.86 eV. Annealing the film increases the activation energy which is 2.1 eV when the film is annealed at a temperature of 450°C for 2 h 相似文献
204.
Mamoru Suzuki Ken Yanagihashi Kazuhiro Tomizawa Tadahiro Gouda Hideharu Oshida 《Electrical Engineering in Japan》1992,112(1):39-51
This paper presents an on-line stabilization control method developed with the aim of maintaining transient stability in a local power system which includes large-capacity generation plants. The characteristics of this method are that the power/angle curve is estimated from the on line active and reactive power measured at the generator terminal, and the optimum generation shedding for stabilization is determined by applying the equal area method to this curve. Simulation tests using detailed models of the power system confirmed that the optimum generation shedding for stabilization could be computed for various fault conditions, both symmetrical or asymmetrical. It was also determined that the on-line data could be sampled for several tens of milliseconds after clearing the fault. Thus, this method provides effective control logic for practical stabilizing systems. 相似文献
205.
H Saito M Zuguchi M Miura S Shinozaki M Hata K Tabayashi 《Canadian Metallurgical Quarterly》1996,167(5):1334-1336
We describe a two-generation family with combined clinical features of myoclonic epilepsy, progressive external ophthalmoplegia (PEO), proximal myopathy, pigmentary retinopathy, progressive deafness, basal ganglia calcification, and ragged-red fibers in a muscle biopsy specimen. One family member died unexpectedly at age 22 years. The molecular tests revealed an A-to-G transition at nucleotide position 3243 of the mitochondrial tRNA(Leu(UUR)) gene. No one in this family had stroke-like episodes. Although the propositus (a 28-year-old woman) had a significant number of white hairs, the percentage of mutant mtDNA in white-hair roots was not different from that in the colored-hair roots. Our findings suggest that the 3243 mutation can be associated with mixed clinical features of myoclonic epilepsy with ragged-red fibers (MERRF) and PEO and that a preferential increase in the levels of the mutant mtDNA is not related to graying of hair, and hence to the hypothesized production of premature aging of cells. 相似文献
206.
The solutions of the diffusion equations with a moving boundary for bubble dissolution (or growth) accompanied by a chemical reaction, were examined. From the viewpoint of the interaction between the convective transport and the chemical reactions, some approximations introduced to solve numerically the equations governing the bubble dissolution (or growth) were studied. For bubble dissolution in glassmelts with equilibrium redox reactions due to refining agents, the applicability of the convection transport approximations employed in the literature was discussed. It was found that our previously proposed model, in which the convective transport is neglected, agrees well with the rigorous finite-difference solution and is more reasonable compared with the approximate models proposed in the literature. Comparisons between our approximate model and the rigorous numerical solution indicate better agreement for dissolution of a bubble by simultaneous mass transfer and chemical reaction, compared with that by only mass transfer. © 1998 Chapman & Hall 相似文献
207.
Enzyme sensors for glucose and uric acid have been developed based on a solid-electrolyte cell using NASICON (Na3Zr2Si2PO12). These potentiometric devices respond reversibly to glucose and uric acid over a concentration range of two orders of magnitude with sensitivities of −54 and −52 mV/decade, respectively. The sensors can be used for a batch-type as well as a flow-through-type measuring system. Primarily the sensors respond to the H2O2 that is produced by the enzymatic reactions. The role of the three-phase region, electrolyte solution, sensing electrode metal and NASICON has been investigated. The liquid electrolyte/sensing electrode metal interface is found to work as a potential-determining as well as a rate-determining interface for the enzyme sensor. 相似文献
208.
K Nonaka B Desjardins H Charbonneau J Légaré T Miura 《Canadian Metallurgical Quarterly》1995,44(3-4):215-222
To study whether apparently more fecund women having delivered twins at first birth have traits of higher twin-proneness, we performed a retrospective cohort study on population-based historical vital records of the 17-18th century French Canadian immigrants and their descendants under natural fertility conditions. Among 24896 mothers who had at least one child, 248 had twin maternities at their first birth (twinning rate = 1.0%). Among 21508 mothers with a valid marriage-first birth interval, twinning rate was 0.97% among prompt conceptions (7.0-11.0 months), with a particularly high rate at the interval of 7.0-8.0 months (2.2%). Marriages in August-October resulted in a higher twinning rate particularly for the slow conceptions than those in the other seasons. Promptly-conceived mothers of twins at the first delivery may seem to have higher fecundity, but subsequent births from these mothers (n = 88) show a lower twinning rate (1.7%) particularly at younger maternal age than from the other mothers who had slowly conceived twins at their first birth (n = 112). The latter show a 4.5% twinning rate as a whole among their second or later births. So-called twin-proneness of a mother, whether genetic or acquired, was not connected to higher conception rate of twin's mothers immediately after marriage. Reduced fecundity, which may have been imposed by some environmental factors, could raise the chance of twinning. 相似文献
209.
210.