全文获取类型
收费全文 | 332568篇 |
免费 | 4127篇 |
国内免费 | 1266篇 |
专业分类
电工技术 | 5533篇 |
综合类 | 2503篇 |
化学工业 | 46960篇 |
金属工艺 | 14061篇 |
机械仪表 | 10496篇 |
建筑科学 | 8177篇 |
矿业工程 | 1431篇 |
能源动力 | 8305篇 |
轻工业 | 24536篇 |
水利工程 | 3410篇 |
石油天然气 | 3565篇 |
武器工业 | 15篇 |
无线电 | 43170篇 |
一般工业技术 | 65109篇 |
冶金工业 | 50919篇 |
原子能技术 | 5312篇 |
自动化技术 | 44459篇 |
出版年
2021年 | 2166篇 |
2020年 | 1562篇 |
2019年 | 1918篇 |
2018年 | 17226篇 |
2017年 | 16163篇 |
2016年 | 13021篇 |
2015年 | 2786篇 |
2014年 | 4166篇 |
2013年 | 11638篇 |
2012年 | 9209篇 |
2011年 | 17572篇 |
2010年 | 14813篇 |
2009年 | 13208篇 |
2008年 | 14878篇 |
2007年 | 15761篇 |
2006年 | 7466篇 |
2005年 | 7628篇 |
2004年 | 7330篇 |
2003年 | 7642篇 |
2002年 | 6542篇 |
2001年 | 6602篇 |
2000年 | 6134篇 |
1999年 | 6442篇 |
1998年 | 16528篇 |
1997年 | 11429篇 |
1996年 | 8834篇 |
1995年 | 6614篇 |
1994年 | 5912篇 |
1993年 | 5850篇 |
1992年 | 4142篇 |
1991年 | 4042篇 |
1990年 | 3857篇 |
1989年 | 3648篇 |
1988年 | 3568篇 |
1987年 | 3017篇 |
1986年 | 2941篇 |
1985年 | 3206篇 |
1984年 | 2926篇 |
1983年 | 2828篇 |
1982年 | 2636篇 |
1981年 | 2542篇 |
1980年 | 2461篇 |
1979年 | 2305篇 |
1978年 | 2107篇 |
1977年 | 2604篇 |
1976年 | 3562篇 |
1975年 | 1764篇 |
1974年 | 1729篇 |
1973年 | 1665篇 |
1972年 | 1465篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Resistance of 19 mold and 6 yeast species to 15 commercial disinfectants was investigated by using a suspension method in which the fungicidal effect and germination time were determined at 20 degrees C. Disinfectants containing 0.5% dodecyldiethylentriaminacetic acid, 10 g of chloramine-T per 1, 2.0% formaldehyde, 0.1% potassium hydroxide, 3.0% hydrogen peroxide, or 0.3% peracetic acid were ineffective as fungicides. The fungicidal effect of quaternary ammonium compounds and chlorine compounds showed great variability between species and among the six isolates of Penicillium roqueforti var. roqueforti tested. The isolates of P roqueforti var. carneum, P. discolor, Aspergillus versicolor, and Eurotium repens examined were resistant to different quaternary ammonium compounds. Conidia and vegetative cells were killed by alcohols, whereas ascospores were resistant. Resistance of ascospores to 70% ethanol increased with age. Both P. roqueforti var. roqueforti and E. repens showed great variability of resistance within isolates of each species. 相似文献
992.
993.
N Muto A Dota T Tanaka N Itoh M Okabe A Inada T Nakanishi K Tanaka 《Canadian Metallurgical Quarterly》1995,18(11):1576-1579
Hinokitiol, a constituent of the wood of Chamaecyparis taiwanensis, was found to induce differentiation of teratocarcinoma F9 cells. When examined by the agar-overlay method, in which expression of plasminogen activator as a differentiation marker protein was detected, this compound exhibited a dose- and time-dependent induction. Induction of differentiation by hinokitiol occurred irreversibly and required its addition for more than 12h. Among its structure-related compounds tested, tropolone and two colchicine-related compounds exerted potent activities comparable to that of hinokitiol. These findings indicate that free tropolone structure in the molecules plays an essential role in inducing differentiation of F9 cells. Hinokitiol showed a strong inhibitory effect of DNA synthesis in very early stages of culture, suggesting that this effect may be responsible for triggering differentiation of F9 cells. 相似文献
994.
ADS Expert is an integrated system that (a) provides suggestions about suitable optimization algorithms for a particular structural optimization problem, (b) it offers explanations and guide lines, in the form of hypertext, that refer to the optimization strategy, optimizer and one dimensional search method, (c) it produces the required gradients for the objective function and the constraints using symbolic differentiation, (d) establishes a direct linking with ADS routines and (e) it monitors the evolution of the optimization process. The system can be used as an educational tool for structural optimization and as an efficient integrated system for small to medium size optimization problems for which the objective function and the constraints are given in the form of explicit functions of the design variables. The system is a Windows application and runs quite satisfactorily on PCs. 相似文献
995.
A Ikeda K Fujimoto I Yoshii S Matsumoto K Nishitani K Ikeda 《Canadian Metallurgical Quarterly》1993,68(4):410-421
Ever since 1974, the cadaver has been embalmed by the arterial embalming method, using pre-embalming fluid with blood clot disperser and cell conditioner for the removal of blood clots and drainage of blood, at the Department of Anatomy of the Kawasaki Medical School. According to this method, the cadavers are always very well fixed so that they can be used for not only anatomical dissection but also research for the vascular system by vasography, kinematics of the joint and other histologic examinations. In this report we have described our embalming procedure concretely and its application to research. 相似文献
996.
997.
K Endo K Morita Y Uchiyama K Takada A Tsujimoto T Dohi 《Canadian Metallurgical Quarterly》1993,62(3):325-328
Influences of drug-induced manipulations of central serotonergic function on lidocaine- and pentylenetetrazol (PTZ)-induced convulsions were examined in mice. Agents that suppressed serotonergic transmission increased, whereas drugs that facilitated serotonin (5-HT) function decreased the incidence of lidocaine-induced convulsions. These treatments had similar influences on the incidence of PTZ-induced convulsions. Lidocaine (10(-5)-10(-3) M) reduced the stimulation evoked [3H]5-HT release from cortical slices, followed with an increased spontaneous [3H] overflow at higher concentrations. These results may suggest that brain 5-HT neurons are causally involved as inhibitory neurons in lidocaine-induced convulsions as in the case of PTZ-induced convulsions. 相似文献
998.
999.
The geo-electrical measuring technique is frequently used for restoration purposes. However, this technique as developed in geology cannot be used without adaptations. The structure that is analysed has geometrical boundaries which influence the measurements and can lead to errors in the interpretation if they are not taken into account. This is illustrated by practical and theoretical tests. In an extensive test programme other aspects of the technique are also considered, such as the influence of electrode configuration and of moisture content. 相似文献
1000.