全文获取类型
收费全文 | 20951篇 |
免费 | 3033篇 |
国内免费 | 1507篇 |
专业分类
电工技术 | 659篇 |
技术理论 | 6篇 |
综合类 | 1597篇 |
化学工业 | 2507篇 |
金属工艺 | 282篇 |
机械仪表 | 394篇 |
建筑科学 | 2739篇 |
矿业工程 | 1003篇 |
能源动力 | 966篇 |
轻工业 | 841篇 |
水利工程 | 2411篇 |
石油天然气 | 8879篇 |
武器工业 | 81篇 |
无线电 | 394篇 |
一般工业技术 | 1060篇 |
冶金工业 | 810篇 |
原子能技术 | 168篇 |
自动化技术 | 694篇 |
出版年
2024年 | 71篇 |
2023年 | 452篇 |
2022年 | 870篇 |
2021年 | 1015篇 |
2020年 | 977篇 |
2019年 | 968篇 |
2018年 | 821篇 |
2017年 | 860篇 |
2016年 | 992篇 |
2015年 | 840篇 |
2014年 | 1460篇 |
2013年 | 1452篇 |
2012年 | 1530篇 |
2011年 | 1679篇 |
2010年 | 1229篇 |
2009年 | 1196篇 |
2008年 | 978篇 |
2007年 | 1324篇 |
2006年 | 1229篇 |
2005年 | 996篇 |
2004年 | 805篇 |
2003年 | 639篇 |
2002年 | 580篇 |
2001年 | 448篇 |
2000年 | 466篇 |
1999年 | 367篇 |
1998年 | 224篇 |
1997年 | 205篇 |
1996年 | 142篇 |
1995年 | 133篇 |
1994年 | 87篇 |
1993年 | 71篇 |
1992年 | 80篇 |
1991年 | 52篇 |
1990年 | 45篇 |
1989年 | 38篇 |
1988年 | 23篇 |
1987年 | 15篇 |
1986年 | 12篇 |
1985年 | 13篇 |
1984年 | 6篇 |
1983年 | 10篇 |
1982年 | 23篇 |
1981年 | 25篇 |
1980年 | 13篇 |
1979年 | 6篇 |
1965年 | 3篇 |
1964年 | 3篇 |
1961年 | 3篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Debadyuti Das 《国际生产研究杂志》2018,56(17):5776-5794
The present work is an attempt to investigate the adoption of sustainable supply chain management (SSCM) practices amongst manufacturing and process based organisations in India and its impact on organisational performance encompassing all three dimensions of sustainability. SSCM practices conceived in the present study include environmental management practices (EMP), socially inclusive practices for employees (SPE), socially inclusive practices for community (SPC), operations practices (OP) and supply chain integration (SCI) which were treated as exogenous variables. Organisational performance considered in this study includes five dimensions, namely environmental performance (EPR), employee-centred social performance (ESP), community-centred social performance (CSP), operations performance (OPR) and competitiveness, which were regarded as endogenous variables. The analysis was carried out with the help of structural equation modelling considering natural logarithm of manpower as a control variable. Few major findings are mentioned. EMP does not have any significant association with OPR, nor does it result in competitiveness. However, when jointly mediated through both EPR and OPR, EMP leads to competitiveness. SPC has significant negative association with competitiveness, when only direct relationship is considered. However, indirect relationship between SPC and competitiveness shows significant positive association when mediated through CSP. The resultant total effect between SPC and competitiveness turns out to be insignificant. Further, OPR fully mediates the relationship between OP and competitiveness. Managerial implications of the findings are discussed. 相似文献
2.
3.
在小子样情况下 ,利用系统和分系统试验数据对导弹的飞行可靠性指标进行评定 ,从数学上说是系统可靠性综合问题 .运用MML SR方法对新型号地地战术导弹的飞行可靠性指标进行评定 ,避免了MML方法在遇到无失败单元时不适用的缺陷 ,在利用地面试验信息方面有其明显优势 ;运用Bayes方法对改进型导弹的飞行可靠性指标进行评定 ,将不同试验阶段的多源试验信息作为验前信息 ,扩大了信息量 .最后 ,对两种方法在工程应用上遇到的问题进行了讨论 ,并给出了解决方法 . 相似文献
4.
5.
6.
阐述了建筑给排水工程师在实际工作中除必须满足国家有关强制性规范外 ,还应采取一系列针对性技术措施 ,以使住宅的环境性能得到良好的控制 ,以提高住宅的品质。 相似文献
7.
�Ĵ������Ȼ�����������б�����Դ̽�� 总被引:11,自引:0,他引:11
本文应用天然气中甲烷、乙烷的碳同位素,甲烷的氢同位素,汞含量及天然气成分等指标,探讨了四川盆地天然气成因分类;并结合地质情况对气源层进行了探讨。 相似文献
8.
储层压力与天然气分布关系——以鄂北塔巴庙地区上古生界储层为例 总被引:2,自引:0,他引:2
通过分析塔巴庙地区储层压力的分布特征,建立了研究区泥岩压实曲线,并对影响和控制该区储层压力的主要因素和机理进行了探讨,对“欠压实”剩余压力、生气增压、抬升引起的降压进行了定量计算。分析结果表明,晚三叠-早白垩世末“欠压实”作用和晚侏罗-早白垩世末烃源岩大量生烃作用使塔巴庙地区上古生界形成异常高压;晚白垩系构造抬升降压,使得现今储层为正常-低异常压力。同时证实了“欠压实”对天然气有压力封盖作用,天然气都分布在最大“欠压实”幅度以下的储层当中。烃源岩生气高峰为晚侏罗-早白垩世末,但天然气大规模运移是在晚白垩世,方向以沿过剩压力梯度降低较快的方向(太原-山西组至下石盒子组)垂向运移,通道主要为裂缝,运移的动力主要为异常高压。由于储层致密,聚集成藏能量有限,造成天然气充注不足、气水分异不好、含气饱和度低。 相似文献
9.
There is widespread application of indicators to the assessment of environmental condition of streams. These indicators are intended for use by managers in making various comparative and absolute assessments and often have a role in resource allocation and performance assessment. Therefore, the problem of formally defining confidence in the results is important but difficult because the sampling strategies used are commonly based on a compromise between the requirements of statistical rigour and the pragmatic issues of access and resources. It is rare to see this compromise explicitly considered and consequently there is seldom quantification of the uncertainty that could affect the confidence a manager has in an indicator. In this paper, we present a method for quantitatively assessing the tradeoffs between sampling density and uncertainty in meeting various monitoring objectives. Assessments using judgement‐based representative reaches are shown to be unreliable; instead a sampling approach is recommended based on the random selection of measuring sites. A detailed dataset was collected along two streams in Victoria, Australia, and the effect of sampling density was assessed by subsampling from this dataset with precision related to the number of sites assessed per reach length and the intensity of the sampling at each site. The sampling scheme to achieve a given precision is shown to depend on the monitoring objective. In particular, three objectives were considered: (1) making a baseline assessment of current condition; (2) change detection; and (3) detection of a critical threshold in condition. Change detection is shown to be more demanding than assessing baseline condition with additional sampling effort required to achieve the same precision. Sampling to detect a critical threshold depends on nominating acceptable values of Type I and II error and the size of the effect to be detected. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
10.
利用寿命周期评价的思想,计算了炼铁生产过程中的环境负荷,并分析了各因素对环境负荷的影响,运用神经网络对炼铁生产过程环境负荷进行了预测。 相似文献