全文获取类型
收费全文 | 1669篇 |
免费 | 20篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 216篇 |
金属工艺 | 12篇 |
机械仪表 | 17篇 |
建筑科学 | 53篇 |
矿业工程 | 5篇 |
能源动力 | 11篇 |
轻工业 | 193篇 |
水利工程 | 17篇 |
石油天然气 | 2篇 |
无线电 | 35篇 |
一般工业技术 | 223篇 |
冶金工业 | 717篇 |
原子能技术 | 10篇 |
自动化技术 | 172篇 |
出版年
2021年 | 23篇 |
2020年 | 15篇 |
2019年 | 14篇 |
2018年 | 10篇 |
2017年 | 10篇 |
2016年 | 22篇 |
2015年 | 9篇 |
2014年 | 22篇 |
2013年 | 74篇 |
2012年 | 47篇 |
2011年 | 71篇 |
2010年 | 51篇 |
2009年 | 55篇 |
2008年 | 59篇 |
2007年 | 73篇 |
2006年 | 79篇 |
2005年 | 62篇 |
2004年 | 66篇 |
2003年 | 70篇 |
2002年 | 59篇 |
2001年 | 37篇 |
2000年 | 23篇 |
1999年 | 28篇 |
1998年 | 55篇 |
1997年 | 44篇 |
1996年 | 58篇 |
1995年 | 28篇 |
1994年 | 28篇 |
1993年 | 37篇 |
1992年 | 23篇 |
1991年 | 13篇 |
1990年 | 31篇 |
1989年 | 30篇 |
1988年 | 23篇 |
1987年 | 25篇 |
1986年 | 26篇 |
1985年 | 23篇 |
1984年 | 34篇 |
1983年 | 35篇 |
1982年 | 14篇 |
1981年 | 21篇 |
1980年 | 17篇 |
1979年 | 15篇 |
1978年 | 25篇 |
1977年 | 12篇 |
1976年 | 14篇 |
1975年 | 18篇 |
1974年 | 12篇 |
1973年 | 10篇 |
1972年 | 7篇 |
排序方式: 共有1689条查询结果,搜索用时 296 毫秒
1.
2.
Software plays an increasingly important role in modern safety-critical systems. Although, research has been done to integrate software into the classical probabilistic risk assessment (PRA) framework, current PRA practice overwhelmingly neglects the contribution of software to system risk. Dynamic probabilistic risk assessment (DPRA) is considered to be the next generation of PRA techniques. DPRA is a set of methods and techniques in which simulation models that represent the behavior of the elements of a system are exercised in order to identify risks and vulnerabilities of the system. The fact remains, however, that modeling software for use in the DPRA framework is also quite complex and very little has been done to address the question directly and comprehensively. This paper develops a methodology to integrate software contributions in the DPRA environment. The framework includes a software representation, and an approach to incorporate the software representation into the DPRA environment SimPRA. The software representation is based on multi-level objects and the paper also proposes a framework to simulate the multi-level objects in the simulation-based DPRA environment. This is a new methodology to address the state explosion problem in the DPRA environment. This study is the first systematic effort to integrate software risk contributions into DPRA environments. 相似文献
3.
MJ de Gortari BA Freking SM Kappes KA Leymaster AM Crawford RT Stone CW Beattie 《Canadian Metallurgical Quarterly》1997,28(4):274-290
We report the evaluation of 1036 bovine microsatellite primer pairs for their suitability as linkage markers in sheep. Approximately 58% (605/1036) of bovine primer pairs amplified a locus in sheep. Sixty-seven per cent (409/605) of amplified loci were detected as polymorphic. Marker heterozygosity, allele number and range of allele sizes were significantly lower in sheep than cattle sampled in this study. However, median fragment size was similar. These data suggest that high-resolution comparative linkage maps between closely related species can be constructed relatively efficiently. 相似文献
4.
Review: Modified Atmosphere Packaging and its effects on the microbiological quality and safety of produce 总被引:10,自引:0,他引:10
Carol A. Phillips 《International Journal of Food Science & Technology》1996,31(6):463-479
Modified Atmosphere Packaging and related technologies are increasingly used to extend shelf-life of fresh produce. This paper reviews the effect of such technology on the spoilage microbiological flora and food-borne pathogens which may be present in produce and also on the organoleptic properties of the product. 相似文献
5.
6.
We used a new injury device that produces consistent spinal cord contusion injuries (T8) in rats to compare the behavioral and histologic effects of methylprednisolone sodium succinate (MPSS) administration, the clinical standard of therapy after acute spinal cord injury (ASCI), with the 21-aminosteroid, U-74006F (U74), and the TRH analogue, YM-14673 (YM), at different trauma doses. Three sequential experiments were conducted: Experiment 1. U74 (3.0/1.5/1.5 mg/kg; 10/5/5 mg/kg; 30/15/15 mg/kg), MPSS (30/15/15 mg/kg), or vehicle were administered intravenously (i.v.) at 5 min, 2 and 6 h after the injury (n = 8/group). U74 (10/5/5 mg/kg) and MPSS animals scored better than controls (Days 8-43) in open field walking (OFW); no other differences were seen between groups. Experiment 2. Dose-response evaluation of MPSS determined more effective doses. Groups (n = 16) receiving 30/30/30/30 mg/kg and 60/60/60/60 mg/kg i.v. at 5 min and 2, 4, and 6 h after the injury had better OFW scores than controls (Days 8-29; Day 29). Both groups performed better than controls (Days 8-29) on inclined plane (IP); 30 mg/kg animals scored higher on Day 29. Percentage tissue spared (%TS) at the lesion center was greater for 60 mg/kg animals (23.4%) than controls (17.3%). Experiment 3. Compounds were administered as in experiment 2 (n = 15/group); MPSS (60/30/30/30 mg/kg) and YM (1/1/1/1 mg/kg and 1 mg/kg/day ip) were most effective. YM and MPSS combination produced no additive effects. YM animals scored better than MPSS and control animals in OFW (Days 8-29) and better than controls on IP (Days 8-29; Day 29) and grid walking (Day 29). MPSS animals scored better than controls on IP (Days 8-29). YM and MPSS groups had greater %TS than controls. This series of experiments demonstrates the utility of this injury model and simple behavioral measures for preclinical assessment of pharmacologic agents. Under these experimental conditions, U74 demonstrated equivalent efficacy to MPSS, and YM demonstrated greater efficacy than MPSS in the treatment of ASCI. 相似文献
7.
Rubichi Sandro; Nicoletti Roberto; Iani Cristina; Umiltà Carol 《Canadian Metallurgical Quarterly》1997,23(5):1353
We investigated whether the Simon effect depends on the orienting of attention. In Experiment 1, participants were required to execute left-right discriminative responses to 2 patterns that were presented to the left or right of fixation. The 2 patterns were similar, and the discrimination was difficult. A letter at fixation signaled whether the current trial was a catch trial. The results showed a reversal of the Simon effect. That is, spatially noncorresponding responses were faster than spatially corresponding responses. In Experiment 2, the discrimination of the relevant stimulus attribute was easy. In Experiment 3, the discrimination of the relevant stimulus attribute was difficult, but the stimulus exposure time was long. In either experiment, the regular Simon effect was reinstated. In Experiment 4, the letter that signaled a catch trial appeared to the left or right of the imperative stimulus. The Simon effect occurred relative to the position of the letter. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
S Uribe-Luna JD Quintana-Hau R Maldonado-Rodriguez M Espinosa-Lara KL Beattie D Farquhar JA Nelson 《Canadian Metallurgical Quarterly》1997,54(3):419-424
The stimulatory effect of phytin added to skim milk on acid production of Lactobacillus casei was examined. Phytin stimulated acid production of L. casei fairly well. The stimulatory effect of phytin on acid production was not shown when phytin was treated with Dowex 50 (H+) and neutralized by NaOH solution. The incinerated product of phytin maintained almost equal stimulatory effect on acid production as that before processing. The addition of Mn2+ in the amount contained in a reagent phytin augmented the stimulatory effect on acid production markedly. The further addition of Fe3+, Ca2+, Mg2+ and PO4(3-) in amounts corresponding to their contents in the preparation of phytin as well as Mn2+ increased the effect slightly. The four preparations of phytin contained 0.045-0.20% of Mn, and the greater the Mn content was, the greater the potentiation of acid production. 相似文献
9.
Gabriel Tsechpenakis Dimitris Metaxas Carol Neidle 《Computer Vision and Image Understanding》2006,104(2-3):140
We present a data-driven dynamic coupling between discrete and continuous methods for tracking objects of high dofs, which overcomes the limitations of previous techniques. In our approach, two trackers work in parallel, and the coupling between them is based on the tracking error. We use a model-based continuous method to achieve accurate results and, in cases of failure, we re-initialize the model using our discrete tracker. This method maintains the accuracy of a more tightly coupled system, while increasing its efficiency. At any given frame, our discrete tracker uses the current and several previous frames to search into a database for the best matching solution. For improved robustness, object configuration sequences, rather than single configurations, are stored in the database. We apply our framework to the problem of 3D hand tracking from image sequences and the discrimination between fingerspelling and continuous signs in American Sign Language. 相似文献
10.
Self-disclosure plays a central role in the development and maintenance of relationships. One way that researchers have explored these processes is by studying the links between self-disclosure and liking. Using meta-analytic procedures, the present work sought to clarify and review this literature by evaluating the evidence for 3 distinct disclosure-liking effects. Significant disclosure-liking relations were found for each effect: (1) People who engage in intimate disclosures tend to be liked more than people who disclose at lower levels, (2) people disclose more to those whom they initially like, and (3) people like others as a result of having disclosed to them. In addition, the relation between disclosure and liking was moderated by a number of variables, including study paradigm, type of disclosure, and gender of the discloser. Taken together, these results suggest that various disclosure-liking effects can be integrated and viewed as operating together within a dynamic interpersonal system. Implications for theory development are discussed, and avenues for future research are suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献