全文获取类型
收费全文 | 3639篇 |
免费 | 187篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 29篇 |
综合类 | 2篇 |
化学工业 | 929篇 |
金属工艺 | 78篇 |
机械仪表 | 84篇 |
建筑科学 | 139篇 |
矿业工程 | 12篇 |
能源动力 | 131篇 |
轻工业 | 273篇 |
水利工程 | 30篇 |
石油天然气 | 8篇 |
无线电 | 272篇 |
一般工业技术 | 747篇 |
冶金工业 | 484篇 |
原子能技术 | 17篇 |
自动化技术 | 594篇 |
出版年
2024年 | 10篇 |
2023年 | 53篇 |
2022年 | 122篇 |
2021年 | 172篇 |
2020年 | 91篇 |
2019年 | 84篇 |
2018年 | 127篇 |
2017年 | 117篇 |
2016年 | 123篇 |
2015年 | 103篇 |
2014年 | 164篇 |
2013年 | 254篇 |
2012年 | 225篇 |
2011年 | 285篇 |
2010年 | 206篇 |
2009年 | 167篇 |
2008年 | 172篇 |
2007年 | 183篇 |
2006年 | 120篇 |
2005年 | 103篇 |
2004年 | 100篇 |
2003年 | 87篇 |
2002年 | 78篇 |
2001年 | 43篇 |
2000年 | 39篇 |
1999年 | 37篇 |
1998年 | 72篇 |
1997年 | 70篇 |
1996年 | 36篇 |
1995年 | 36篇 |
1994年 | 27篇 |
1993年 | 25篇 |
1992年 | 24篇 |
1991年 | 16篇 |
1990年 | 28篇 |
1989年 | 18篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 11篇 |
1985年 | 17篇 |
1984年 | 9篇 |
1983年 | 13篇 |
1982年 | 9篇 |
1981年 | 13篇 |
1980年 | 11篇 |
1979年 | 10篇 |
1977年 | 9篇 |
1976年 | 21篇 |
1975年 | 8篇 |
1974年 | 9篇 |
排序方式: 共有3829条查询结果,搜索用时 10 毫秒
91.
Mass Spectrometry of Natural Products. XV. Comparative Positive-Negative Ion Mass Spectrometry of Azidogibberellins The fragmentation behaviour of 1-azido-3-hydroxy-gibberellin derivatives has been studied by means of positive and negative ion mass spectrometry, high resolution and metastable transitions. The results obtained allow a mass spectrometric distinction to be made between epimers with different stereochemistry of the ring A substituents. 相似文献
92.
93.
94.
Public clients in the construction sector face a number of challenges in designing, procuring and managing major construction projects. The client’s role in bringing about project delivery has more recently been emphasized, particularly with respect to developing capabilities that facilitate the coordinating of projects through its different phases. In line with these developments, this paper sets out to examine the management of capabilities in a client organization through the lens of the dynamic capabilities framework. In particular, what is investigated is how the client organization senses, seizes and transforms opportunities. In pursuit of this objective, an exploratory case study approach is adopted which examines one of Sweden’s largest public client organizations. The study explores the concept of dynamic capabilities and its applicability to the public construction context. Although the usefulness of dynamic capabilities as an interpretive framework is recognized, it is suggested that the concept of dynamic capabilities is inadequate for addressing the specific context in which public client organizations operate. Particularly with respect to the project-based characteristic of these organizations and the difficulty in framing what constitutes “competitive advantage” for public organizations. 相似文献
95.
R. Adam Rebeles A. Hermanne S. Takcs F. Trknyi S.F. Kovalev A. Ignatyuk 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2007,260(2):672-684
In the frame of a systematic study of light ion induced threshold reactions on natural tin (Sn) excitation functions for alpha particles induced reactions are presented in a 12–38 MeV energy domain. Using a stacked foil activation method the following radioisotopes were identified: 116Te, 117Te, 118Te, 119Te, 121Te, 123Te, 117Sb, 118Sb, 120Sb, 122Sb, 124Sb, 126Sb, 117Sn, 111In. The experimental cross sections for these isotopes are presented for the first time in this energy range and a direct comparison with values calculated with the ALICE-IPPE code is discussed. Possible use of these data for production of some isotopes relevant in nuclear medicine is suggested. 相似文献
96.
97.
Switonski Adam Josinski Henryk Wojciechowski Konrad 《Multidimensional Systems and Signal Processing》2019,30(3):1437-1468
Multidimensional Systems and Signal Processing - The paper is a comprehensive study on classification of motion capture data on the basis of dynamic time warping (DTW) transform. It presents both... 相似文献
98.
Adam S. Wilk Zhaoli Tang Courtney Hoge Laura C. Plantinga Janice P. Lea 《Hemodialysis international. International Symposium on Home Hemodialysis》2019,23(4):479-485
Introduction: Compared to traditional in‐center hemodialysis (HD), in‐center nocturnal dialysis (INHD) is characterized by longer sessions and nighttime administration, which may lead to better outcomes for some patients. Given the importance of patient choice in the decision to initiate INHD, we explored associations between patients’ psychosocial characteristics and their receipt of INHD. Methods: Among hemodialysis patients at a medium‐sized dialysis organization, we identified INHD patients as those for whom ≥80% of dialysis sessions were INHD sessions—starting at 6:30 pm or later and lasting ≥5 hours—over the 3 months (≥20 sessions total) after their first INHD session. We extracted dialysis session data from electronic medical records and psychosocial data from social worker assessments. We tested associations of patients’ psychosocial characteristics—as well as demographic and clinical characteristics—with INHD receipt among all hemodialysis patients (INHD and HD) in bivariate analyses and multivariable logistic regression models. Findings: Among 759 patients with complete data, we identified 47 (6.2%) as INHD patients. On average, these patients were more likely than HD patients to be employed (full‐time 10.6% vs. 5.2%; part‐time 17.0% vs. 4.2%; P < 0.001), and they were significantly less likely to require ambulatory assistance (14.9% vs. 39.6%, P < 0.001). In multivariable regressions, we found that part‐time employment (versus being unemployed) was associated with a 7.1 percentage‐point higher likelihood of being an INHD patient (P = 0.01), and the negative association with ambulatory assistance needs approached statistical significance (P = 0.056). No other psychosocial factors included in this main regression analysis were statistically significantly associated with INHD patient status. Discussion: Researchers comparing the outcomes of patients undergoing INHD versus other treatment modalities will need to account for differences in employment status—and other factors like requiring ambulatory assistance and age which may predict the ability to work—between INHD users and comparison patients to avoid bias in estimates. 相似文献
99.
100.
Journal of Failure Analysis and Prevention - A failure analysis investigation was performed on the remnants of a carbon fiber rudder stock that fractured during operation on a vessel in an offshore... 相似文献