全文获取类型
收费全文 | 8719篇 |
免费 | 294篇 |
国内免费 | 210篇 |
学科分类
工业技术 | 9223篇 |
出版年
2023年 | 50篇 |
2022年 | 62篇 |
2021年 | 118篇 |
2020年 | 97篇 |
2019年 | 80篇 |
2018年 | 185篇 |
2017年 | 179篇 |
2016年 | 183篇 |
2015年 | 156篇 |
2014年 | 161篇 |
2013年 | 401篇 |
2012年 | 328篇 |
2011年 | 382篇 |
2010年 | 321篇 |
2009年 | 277篇 |
2008年 | 358篇 |
2007年 | 308篇 |
2006年 | 317篇 |
2005年 | 274篇 |
2004年 | 245篇 |
2003年 | 232篇 |
2002年 | 251篇 |
2001年 | 214篇 |
2000年 | 204篇 |
1999年 | 213篇 |
1998年 | 585篇 |
1997年 | 390篇 |
1996年 | 258篇 |
1995年 | 200篇 |
1994年 | 204篇 |
1993年 | 217篇 |
1992年 | 103篇 |
1991年 | 73篇 |
1990年 | 111篇 |
1989年 | 118篇 |
1988年 | 91篇 |
1987年 | 78篇 |
1986年 | 81篇 |
1985年 | 78篇 |
1984年 | 68篇 |
1983年 | 63篇 |
1982年 | 53篇 |
1981年 | 85篇 |
1979年 | 53篇 |
1978年 | 53篇 |
1977年 | 75篇 |
1976年 | 65篇 |
1975年 | 55篇 |
1971年 | 84篇 |
1970年 | 40篇 |
排序方式: 共有9223条查询结果,搜索用时 15 毫秒
1.
No authorship indicated 《Canadian Metallurgical Quarterly》2004,59(8):673
Provides the biography of Sheldon Cohen and announces that he has received the APA Award for Distinguished Scientific Contributions (2004) for his elegant research in psychoneuroimmunology. The award citation and a selected bibliography are also provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
2.
量子密码技术被认为是绝对安全的加密技术。近年来,在美国、德国、日本和中国,相关研究都取得了明显进展。2004年6月,世界上第一个量子密码通信网络在美国马萨诸塞州剑桥城正式投入运行,标志着这一技术迈上了新台阶。据相关机构估算,量子保密通信系统一旦商用,将形成高达10亿美元的市场。 相似文献
3.
Nitrous oxide (N2O) effects were evaluated, as a behavioural model of inert gas narcosis, in rats performing a vigilance task in which they were required to respond to a slight luminous increment of the house-light. A dose-related decrease of correct responses was produced by the tested range of concentrations of N2O (from 30 to 70% N2O), with a parallel increase of anticipatory responses up to 60% N2O and a dramatic increase of omissions at 70% N2O. The influence of preparatory period duration on hits delays suggested a 'conditional probability effect' conserved under N2O. Pretreatment of animals with flumazenil (a central benzodiazepine receptor antagonist) did not improve performance under 40% N2O. Naltrexone, an opiate receptor antagonist, however, increased the N2O-induced deficits. These results suggest that benzodiazepine receptors are not involved in N2O-induced impairments in this attentional task, but opiate mechanisms may be implicated. 相似文献
4.
No authorship indicated 《Canadian Metallurgical Quarterly》1997,52(8):912
Presents a list of American Psychological Foundation contributors for 1996. Individuals listed have donated through gifts of cash, securities, royalties, or through the Legacy Club (LC). LC donations are provided in wills, life insurance policies, trusts, and other gift arrangements. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
F. J. Carrière H. Sekiguchi N. N. Surin V. A. Kotelnikov Ya. S. Vygodskii 《Polymer Bulletin》1995,35(4):441-448
Summary Polyimides (PI) having different molecular weights were prepared by condensation of oxydiphthalic anhydride with 9,9-bis-(4-aminophenyl)fluorene in nitrobenzene solution at 180°C. These polyimides carried two amino chain ends which allowed us to fix polycaprolactam chains (PA6) to obtain PA6-PI-PA6 type copolymers. The elemental analysis and infrared spectroscopic determination gave the proportion of PA6 (or PI) in the copolymers. The studies of thermal properties-DSC and TGA-allowed us to characterize the copolymers. 相似文献
6.
钻井液用BDY-1便携式堵漏仪 总被引:3,自引:2,他引:1
在堵漏过程中,对堵漏材料和堵漏浆配方的优选是决定堵漏成功的关键。为了能在现场对堵漏进行评价,研制出BDY-1便携式堵漏仪,该堵漏仪主要由不锈钢钢柱圈钢,压力表等加工而成,该堵漏仪体积小,重量轻,价格低,仅为国产堵漏仪的1/20。试验结果表明BDY-1便携式堵漏仪操作简便,可快速对堵漏材料进行评价并筛选出堵漏配方;数据重复性好,准确可靠,能达到进口或国产堵漏仪的水平;在模拟漏层选定后,可采用多套压力梯度,对堵漏浆封堵效果进行评价,在压力梯度选定后,可评价堵漏浆对不同类型漏层的封堵效果;如果扩大压力范围,可对封堵后的漏层进行破裂试验,从而确定合理的钻井施工参数;适用现场操作和应用。 相似文献
7.
茅金根 ,梁秀文 ,杨午阳 ,冯有奎 .等偏移距自动初至静校正 .石油地球物理勘探 ,2 0 0 2 ,37(5 ) :4 6 9~ 4 72 本文提出一种自动计算静校正量的新方法。它首先在等偏移距道集内对相邻道的初至波采用高精度相关构建一个关于炮、检时差的超大矩阵方程 ,然后采用优化统计迭代算法求解炮点和检波点的静校正量 ,并用概率分布函数确定精确的炮、检静校正量 ,最后用误差校正函数消除炮、检静校正误差。实际资料处理结果表明 ,本方法自动、省时、精度高。 相似文献
8.
No authorship indicated 《Canadian Metallurgical Quarterly》2003,58(11):852
Presents the 2003 APA Award for Distinguished Scientific Applications of Psychology. A list of the members of the APA committee who selected the recipients for this year and a list of the previous recipients of this award from 1973 through 2003 are provided. The award recipients for 2003 are Stephen J. Ceci and Elizabeth F. Loftus. The award citation, biography, selected bibliography and the award addresses for both award recipients are included. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
No authorship indicated 《Canadian Metallurgical Quarterly》2005,41(1):291
Presents a brief tribute to Irving B. Harris upon his passing. Harris played a central role in launching the Harris School of Public Policy Studies and the Center for Human Potential and Public Policy at the University of Chicago. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
No authorship indicated 《Canadian Metallurgical Quarterly》2007,62(9):1058
Provides the 2007 reports of APA's Regional Associations. Included are the annual meeting reports from the Eastern Psychological Association, Midwestern Psychological Association, New England Psychological Association, Rocky Mountain Psychological Association, Southeastern Psychological Association, Southwestern Psychological Association, and Western Psychological Association. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献