全文获取类型
收费全文 | 5222篇 |
免费 | 114篇 |
国内免费 | 19篇 |
专业分类
电工技术 | 32篇 |
综合类 | 6篇 |
化学工业 | 757篇 |
金属工艺 | 103篇 |
机械仪表 | 74篇 |
建筑科学 | 88篇 |
矿业工程 | 6篇 |
能源动力 | 102篇 |
轻工业 | 135篇 |
水利工程 | 17篇 |
石油天然气 | 14篇 |
无线电 | 299篇 |
一般工业技术 | 697篇 |
冶金工业 | 2565篇 |
原子能技术 | 26篇 |
自动化技术 | 434篇 |
出版年
2023年 | 19篇 |
2022年 | 35篇 |
2021年 | 64篇 |
2020年 | 53篇 |
2019年 | 47篇 |
2018年 | 72篇 |
2017年 | 55篇 |
2016年 | 74篇 |
2015年 | 53篇 |
2014年 | 74篇 |
2013年 | 187篇 |
2012年 | 112篇 |
2011年 | 155篇 |
2010年 | 141篇 |
2009年 | 162篇 |
2008年 | 129篇 |
2007年 | 128篇 |
2006年 | 107篇 |
2005年 | 92篇 |
2004年 | 108篇 |
2003年 | 91篇 |
2002年 | 84篇 |
2001年 | 77篇 |
2000年 | 69篇 |
1999年 | 131篇 |
1998年 | 717篇 |
1997年 | 417篇 |
1996年 | 277篇 |
1995年 | 176篇 |
1994年 | 152篇 |
1993年 | 169篇 |
1992年 | 86篇 |
1991年 | 76篇 |
1990年 | 70篇 |
1989年 | 70篇 |
1988年 | 65篇 |
1987年 | 54篇 |
1986年 | 62篇 |
1985年 | 57篇 |
1984年 | 40篇 |
1983年 | 41篇 |
1982年 | 32篇 |
1981年 | 41篇 |
1980年 | 44篇 |
1979年 | 17篇 |
1978年 | 26篇 |
1977年 | 79篇 |
1976年 | 138篇 |
1974年 | 19篇 |
1973年 | 24篇 |
排序方式: 共有5355条查询结果,搜索用时 15 毫秒
21.
E Eng M Veniant J Floege J Fingerle CE Alpers J Menard JP Clozel RJ Johnson 《Canadian Metallurgical Quarterly》1994,7(2):177-185
Previous research in this laboratory has shown that preweaning and postweaning juvenile meadow voles, Microtus pennsylvanicus, can acquire a spatial task, the Morris water-maze task. The present study examined the influence of age of juvenile acquisition ("before weaning" (BW; Day 10 and 15 after birth) and "after weaning" (AW; Day 20 and 25 after birth)) of a spatial task on subsequent re-acquisition of the same hidden-platform spatial water-maze task. This study also compared sex differences and litter sex-ratio effects on reacquisition performance. Fifteen litters of adults were re-tested in the same water maze 6 weeks after being initially tested as juveniles. All analyses were conducted using a covariate that removed the group differences in the original task performance. Adult voles from female-biased litters, that had previously learned the task at an older juvenile age (AW), reacquired the same task faster than adults that had previously learned the task at a younger juvenile age (BW). In the adult BW group there was also a significant litter sex-ratio effect such that voles born into a female-biased litter re-acquired the task more slowly than did voles born into a male-biased litter. There were no significant sex or litter sex-ratio effects on spatial learning in the AW group. These results show that adult meadow voles can require a spatial task more quickly if they initially learned the task at an older juvenile age, suggestive of a period of infantile amnesia. In addition, these results indicate that the litter sex-ratio can affect adult spatial performance, suggesting that the relative amount of androgens in utero may influence the development of sexually-dimorphic spatial ability in adulthood. 相似文献
22.
Identification of statistical patterns from observed time series of spatially distributed sensor data is critical for performance monitoring and decision making in human-engineered complex systems, such as electric power generation, petrochemical, and networked transportation. This paper presents an information-theoretic approach to identification of statistical patterns in such systems, where the main objective is to enhance structural integrity and operation reliability. The core concept of pattern identification is built upon the principles of Symbolic Dynamics, Automata Theory, and Information Theory. To this end, a symbolic time series analysis method has been formulated and experimentally validated on a special-purpose test apparatus that is designed for data acquisition and real-time analysis of fatigue damage in polycrystalline alloys. 相似文献
23.
24.
CE McMahon 《Canadian Metallurgical Quarterly》1976,2(3):112-115
Despite its impressive rate of growth in the past decades, an increasing amount if dissatisfaction with the area of psychosomatic medicine is reflected in recent literature. The discipline's failures relate to concepts of pathogenesis and therapeutic application of research findings. These failures are explained as a necessary consequence of the philosophical tenet of mind-body dualism which underlies medical theory. It is urged that advocates of psychosomatic medicine give the concept of "holism" meaning at the most fundamental level by establishing a rational basis for theory, or else forsake this line of research for others which yield causal relationships conductive to effective therapy. 相似文献
25.
Ray E.Henry C.L.Shieh 《华东电力》2008,36(2):12-15
美国火电厂烟气排放限值及控制技术在过去的37年内不断发展进步.受限制的排放物越来越多,而且对每种污染物的限值日益严格.总结了当今美国使用的排放限值及控制技术,并展望了未来的排放限值及潜在的排放控制技术. 相似文献
26.
Anna N. Boss Abhirup Banerjee Michail Mamalakis Surajit Ray Andrew J. Swift Craig Wilkie Joseph W. Fanstone Bart Vorselaars Joby Cole Simonne Weeks Louise S. Mackenzie 《International journal of molecular sciences》2022,23(13)
Acute kidney injury (AKI) is a prevalent complication in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positive inpatients, which is linked to an increased mortality rate compared to patients without AKI. Here we analysed the difference in kidney blood biomarkers in SARS-CoV-2 positive patients with non-fatal or fatal outcome, in order to develop a mortality prediction model for hospitalised SARS-CoV-2 positive patients. A retrospective cohort study including data from suspected SARS-CoV-2 positive patients admitted to a large National Health Service (NHS) Foundation Trust hospital in the Yorkshire and Humber regions, United Kingdom, between 1 March 2020 and 30 August 2020. Hospitalised adult patients (aged ≥ 18 years) with at least one confirmed positive RT-PCR test for SARS-CoV-2 and blood tests of kidney biomarkers within 36 h of the RT-PCR test were included. The main outcome measure was 90-day in-hospital mortality in SARS-CoV-2 infected patients. The logistic regression and random forest (RF) models incorporated six predictors including three routine kidney function tests (sodium, urea; creatinine only in RF), along with age, sex, and ethnicity. The mortality prediction performance of the logistic regression model achieved an area under receiver operating characteristic (AUROC) curve of 0.772 in the test dataset (95% CI: 0.694–0.823), while the RF model attained the AUROC of 0.820 in the same test cohort (95% CI: 0.740–0.870). The resulting validated prediction model is the first to focus on kidney biomarkers specifically on in-hospital mortality over a 90-day period. 相似文献
27.
Jason K. Iles Raminta Zmuidinaite Christoph Sadee Anna Gardiner Jonathan Lacey Stephen Harding Gregg Wallis Roshani Patel Debra Roblett Jonathan Heeney Helen Baxendale Ray Kruse Iles 《International journal of molecular sciences》2022,23(11)
The involvement of immunoglobulin (Ig) G3 in the humoral immune response to SARS-CoV-2 infection has been implicated in the pathogenesis of acute respiratory distress syndrome (ARDS) in COVID-19. The exact molecular mechanism is unknown, but it is thought to involve this IgG subtype’s differential ability to fix, complement and stimulate cytokine release. We examined the binding of convalescent patient antibodies to immobilized nucleocapsids and spike proteins by matrix-assisted laser desorption/ionization–time of flight (MALDI-ToF) mass spectrometry. IgG3 was a major immunoglobulin found in all samples. Differential analysis of the spectral signatures found for the nucleocapsid versus the spike protein demonstrated that the predominant humoral immune response to the nucleocapsid was IgG3, whilst for the spike protein it was IgG1. However, the spike protein displayed a strong affinity for IgG3 itself, as it would bind from control plasma samples, as well as from those previously infected with SARS-CoV-2, similar to the way protein G binds IgG1. Furthermore, detailed spectral analysis indicated that a mass shift consistent with hyper-glycosylation or glycation was a characteristic of the IgG3 captured by the spike protein. 相似文献
28.
Researchers have been closely studying how information technology services became a routine part of our lives. Studies have found that users who routinely use online services either consciously develop loyalty or automatically develop a habit. But many studies now mix the elements of conscious and automatic use despite the great differences in these phenomena. This study proposes a new theoretical framework of how the conscious and automatic mechanisms simultaneously, but differentially, regulate postadoption phenomena in the context of online information services. An empirical test confirms that these two mechanisms have highly discernible patterns that researchers and managers alike must heed. 相似文献
29.
A Critical Grain Size Concept to Predict the Impact Transition Temperature of Ti-Microalloyed Steels
Based on the assumption that local principal stress remains the same everywhere within a ferrite grain, a critical value of grain size can be determined for a fixed TiN particle size. When the grain size is smaller than the critical size, grain boundary is expected to resist the propagation of a micro-crack that is initiated from a TiN particle. Using this concept, an attempt has been made to predict the local cleavage fracture stress and 27J impact transition temperature (ITT) of different Ti-microalloyed steels, which were subjected to (instrumented) Charpy impact testing. 相似文献
30.