全文获取类型
收费全文 | 683篇 |
免费 | 36篇 |
专业分类
电工技术 | 4篇 |
综合类 | 11篇 |
化学工业 | 219篇 |
金属工艺 | 8篇 |
机械仪表 | 9篇 |
建筑科学 | 40篇 |
矿业工程 | 4篇 |
能源动力 | 17篇 |
轻工业 | 161篇 |
水利工程 | 6篇 |
石油天然气 | 6篇 |
无线电 | 25篇 |
一般工业技术 | 79篇 |
冶金工业 | 69篇 |
原子能技术 | 4篇 |
自动化技术 | 57篇 |
出版年
2023年 | 9篇 |
2022年 | 21篇 |
2021年 | 32篇 |
2020年 | 16篇 |
2019年 | 13篇 |
2018年 | 23篇 |
2017年 | 13篇 |
2016年 | 19篇 |
2015年 | 30篇 |
2014年 | 29篇 |
2013年 | 50篇 |
2012年 | 30篇 |
2011年 | 36篇 |
2010年 | 32篇 |
2009年 | 31篇 |
2008年 | 43篇 |
2007年 | 27篇 |
2006年 | 32篇 |
2005年 | 24篇 |
2004年 | 25篇 |
2003年 | 19篇 |
2002年 | 21篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 7篇 |
1998年 | 8篇 |
1997年 | 2篇 |
1996年 | 6篇 |
1995年 | 11篇 |
1994年 | 12篇 |
1993年 | 4篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1983年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1968年 | 2篇 |
1956年 | 1篇 |
1954年 | 1篇 |
1948年 | 13篇 |
1919年 | 1篇 |
排序方式: 共有719条查询结果,搜索用时 0 毫秒
1.
2.
3.
Peroxide crosslinking of unplasticized poly(vinyl chloride) with trimethylolpropane trimethacrylate was investigated. Formulations used in this work contained a nontoxic lead‐free stabilizer and showed good color and heat stability. The samples were examined by differential scanning calorimetry, and their tensile properties were measured at room temperature and at 130°C. Gel content or tetrahydrofuran‐insoluble material was measured as an indication of crosslinking. It was shown that premature crosslinking could be avoided during processing and that 190°C was the optimum processing temperature for maximum gel content. The residual unsaturation was monitored by using FTIR spectroscopy. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers 相似文献
4.
Marie L. Borum Kathleen L. Shehan Hans Fromm Saleem Jahangeer Marianne K. Floor Oliver Alabaster 《Lipids》1992,27(12):999-1004
The effect and possible interactive influence of different dietary amounts of wheat bran, fat and calcium on the fecal excretion,
concentration and composition of bile acids was studied in Fischer-344 rats. The fecal bile acids were analyzed using gas-liquid
chromatography. Dietary wheat bran increased both total bile acid excretion and fecal weight without changes in fecal bile
acid concentration. The proportion of fecal hyodeoxycholic acid decreased with increasing dietary fiber, whereas that of lithocholic
and deoxycholic acids increased significantly with fiber intake. The percent content of fecal chenodeoxycholic acid did not
change. Increasing dietary fat led to an increase in bile acid excretion without changes in either fecal weight or bile acid
concentration. In contrast, the level of dietary calcium did not affect the total excretion of bile acids. However, since
calcium increased the fecal weight, it consequently diluted bile acids and decreased their fecal concentration. Dietary fat
and calcium had no influence on fecal bile acid composition. There were no interactive effects of wheat bran, fat and calcium
on fecal bile acids. The finding in this study that dietary fiber, fat and calcium induce significant changes in fecal bile
acids may be of relevance to the potential of bile acids to promote carcinogenesis. 相似文献
5.
This paper criticizes the current narrow view on the role of universities in knowledge‐based economies. We propose to extend the current policy framework of universities in national innovation systems (NIS) to a more dynamic one, based on evolutionary economic principles. The main reason is that this dynamic view fits better with the practice of innovation processes. We contribute on ontological and methodological levels to the literature and policy discussions on the effectiveness of university‐industry knowledge transfer and the third mission of universities. We conclude with a discussion of the policy implications for the main stakeholders. 相似文献
6.
Applications requiring variable-precision arithmetic often rely on software implementations because custom hardware is either unavailable or too costly to build. By using the flexibility of the Xilinx XC4010 field programmable gate arrays, we present a hardware implementation of square root that is easily tailored to any desired precision. Our design consists of three types of modules: a control logic module, a data path module to extend the precision in 4-bit increments, and an interface module to span multiple chips. Our data path design avoids the common problem of large fan-out delay in the critical path. Cycle time is independent of precision, and operation latency can be independent of interchip communication delays.Notation Sj
square root digit of weight 2–j
-
S
j
{–1, 0, 1}
- S[j]
computed square root value as of stepj
- S
j
s
sign bit in the representation ofS
j
in sign and magnitude form
-
S
j
m
magnitude bit in the representation ofS
j
in sign and magnitude form
- w[j]
residual at stepj in two's complement carry-save representation
-
a
sum vector in the carry-save representation of 2w[j]
-
b
carry vector in the carry-save representation of 2w[j]
-
a
i
bit of weight 2–i in the sum vector,a
- bi
bit of weight 2–i in the carry vector,b
- T[j]=–S[j – 1]sj – s
j
2
2–(j+1)
T
i
bit of weight 2–i inT 相似文献
7.
8.
9.
In order to increase safety in Swedish farming an intervention methodology to influence attitudes and behaviour was tested. Eighty eight farmers and farm workers in nine groups gathered on seven occasions during 1 year. The basic concept was to create socially supportive networks and encourage discussions and reflection, focusing on risk manageability. Six of the groups made structured incident/accident analyses. Three of the latter groups also received information on risks and accident consequences. Effects were evaluated in a pre-post questionnaire using six-graded scales. A significant increase in safety activity and significant reduction in stress and risk acceptance was observed in the total sample. Risk perception and perceived risk manageability did not change. Analysing incidents/accidents, but not receiving information, showed a more positive outcome. Qualitative data indicated good feasibility and that the long duration of the intervention was perceived as necessary. The socially supportive network was reported as beneficial for the change process. 相似文献
10.
A critical performance issue for a number of scientific and engineering applications is the efficient transfer of data to secondary storage. Languages such as High Performance Fortran (HPF) have been introduced to allow programming distributed-memory systems at a relatively high level of abstraction. However, the present version of HPF does not provide appropriate constructs for controlling the parallel I/O capabilities of these systems. In this paper, constructs to specify parallel I/O operations on multidimensional arrays in the context of HPF are proposed. The paper also presents implementation concepts that are based on the HPF compiler VFC and the parallel I/O run-time system Panda. Experimental performance results are discussed in the context of financial management and traffic simulation applications. 相似文献