全文获取类型
收费全文 | 1960篇 |
免费 | 13篇 |
专业分类
电工技术 | 15篇 |
化学工业 | 139篇 |
金属工艺 | 22篇 |
机械仪表 | 20篇 |
建筑科学 | 91篇 |
矿业工程 | 2篇 |
能源动力 | 22篇 |
轻工业 | 199篇 |
水利工程 | 15篇 |
石油天然气 | 4篇 |
无线电 | 171篇 |
一般工业技术 | 172篇 |
冶金工业 | 965篇 |
原子能技术 | 16篇 |
自动化技术 | 120篇 |
出版年
2019年 | 14篇 |
2018年 | 16篇 |
2017年 | 16篇 |
2016年 | 15篇 |
2015年 | 14篇 |
2014年 | 19篇 |
2013年 | 33篇 |
2012年 | 37篇 |
2011年 | 59篇 |
2010年 | 38篇 |
2009年 | 45篇 |
2008年 | 47篇 |
2007年 | 39篇 |
2006年 | 37篇 |
2005年 | 37篇 |
2004年 | 39篇 |
2003年 | 29篇 |
2002年 | 26篇 |
2001年 | 37篇 |
2000年 | 17篇 |
1999年 | 55篇 |
1998年 | 271篇 |
1997年 | 200篇 |
1996年 | 106篇 |
1995年 | 89篇 |
1994年 | 63篇 |
1993年 | 62篇 |
1992年 | 23篇 |
1991年 | 20篇 |
1990年 | 26篇 |
1989年 | 18篇 |
1988年 | 27篇 |
1987年 | 27篇 |
1986年 | 23篇 |
1985年 | 26篇 |
1984年 | 20篇 |
1983年 | 21篇 |
1982年 | 22篇 |
1981年 | 19篇 |
1980年 | 23篇 |
1979年 | 13篇 |
1978年 | 15篇 |
1977年 | 39篇 |
1976年 | 60篇 |
1975年 | 12篇 |
1974年 | 7篇 |
1973年 | 11篇 |
1972年 | 8篇 |
1971年 | 10篇 |
1970年 | 9篇 |
排序方式: 共有1973条查询结果,搜索用时 0 毫秒
41.
IS Balakhovski? 《Canadian Metallurgical Quarterly》1998,(5):33-38
Traditionally, the term "precision" denotes the quality of work, uniting the correctness and reproducibility of results. However, it can have another sense: the minimal difference between the specimens, detectable by this or that device or method. In order to rule out misunderstanding, we propose to use the term "measuring precision", if the term is used in its second meaning. It is easy to assess the measuring precision by statistical processing of large scope of data: if the histogram shows waves which disappear after the histogram step is increased, this means that the device and method used in this study permit biochemical analysis only at measuring precision corresponding to the histogram step at which the waves disappear. A table of measuring precision values is offered for 19 methods realized using the Labsystems FP-900 device (Finland) In many cases it is obviously low. 相似文献
42.
In recent years integrated models have been developed to simulate the entire urban wastewater system, including urban drainage systems, wastewater treatment plants, and receiving waterbodies. This paper uses such an integrated urban wastewater model to analyze the frequency of receiving water quality in an urban wastewater system with the aim of assessing the overall system performance during rainfall events. The receiving water quality is represented by two indicators: event mean dissolved oxygen (DO) concentration and event mean ammonium concentration. The compliance probability of the water quality indicators satisfying a specific threshold is used to represent the system performance, and is derived using the rainfall events from a series of 10 years' rainfall data. A strong correlation between the depth of each rainfall event and the associated volume of combined sewer overflow (CSO) discharges is revealed for the case study catchment, while there is a low correlation between the intensity/duration of the rainfall event and the volume of the CSO discharges. The frequency analysis results obtained suggest that the event mean DO and ammonium concentrations have very different characteristics in terms of compliance probabilities at two discharging points for CSO and wastewater treatment plant effluent, respectively. In general, the simulation results provide an understanding of the performance of the integrated urban wastewater system and can provide useful information to support water quality management. 相似文献
43.
Richard Ashley David Blackwood Nicki Souter Sarah Hendry Jim Moir Judith Dunkerley John Davies David Butler Andrew Cook Jim Conlin Martin Squibbs Andrew Britton Peter Goldie 《Canadian Metallurgical Quarterly》2005,131(2):206-215
The study presented is an example of the assessment of the relative sustainability of either option for disposal of domestic sanitary waste, either via the toilet or via the solid waste route. This required an evaluation of the total (social, economic, environmental, and technical) benefit/cost of implementing and adopting the alternative routes and an assessment of public responsiveness to encouragement to change sanitary waste disposal practices. It illustrates how, even for an apparently straightforward either/or question, the assessment of relative sustainability is complex and the amount of data needed to quantify sustainability indicators is prodigious. The study also provides an appraisal of the effectiveness of public campaigns to reduce waterborne disposal. Important information regarding public attitude and behavior in relation to wastewater systems has been acquired and lessons for ways of encouraging behavioral change to more sustainable ways of living have been gleaned. 相似文献
44.
César Muñoz Víctor Carreño Gilles Dowek Ricky Butler 《International Journal on Software Tools for Technology Transfer (STTT)》2003,4(3):371-380
Safety assessment of new air traffic management systems is a main issue for civil aviation authorities. Standard techniques
such as testing and simulation have serious limitations in new systems that are significantly more autonomous than the older
ones. In this paper, we present an innovative approach for establishing the correctness of conflict detection systems. Fundamental
to our approach is the concept of trajectory, and how we represent a continuous physical trajectory by a continuous path in
the x-y plane constrained by physical laws and operational requirements. From the model of trajectories, we extract, and formally
prove, high-level properties that can serve as a framework to analyze conflict scenarios. We use the AILS (Airborne Information
for Lateral Spacing) alerting algorithm as a case study of our approach.
Published online: 19 November 2002 相似文献
45.
M Hara YM Liu L Zhen IS Cohen H Yu P Danilo K Ogino JP Bilezikian MR Rosen 《Canadian Metallurgical Quarterly》1997,96(10):3704-3709
BACKGROUND: The classic calciotropic hormone parathyroid hormone (PTH) and its paracrine factor parathyroid hormone-related protein (PTHrP) both increase heart rate. METHODS AND RESULTS: We used standard electrophysiological techniques to study the effects of PTH and PTHrP on isolated rabbit sinus node, isolated canine Purkinje fibers, and disaggregated rabbit sinus node myocytes. Sinus node maximum diastolic potential, activation voltage, and amplitude were unchanged by PTH or PTHrP (P>.05). However, the slope of phase 4 and the automatic rate were increased at PTH and PTHrP > or = 10 nmol/L (P<.05). Comparable results were seen in canine Purkinje fibers. We then used the perforated-patch technique to study the I(f) pacemaker current in sinus node. PTH 12.5 nmol/L and PTHrP 12.5 to 18 nmol/L increased I(f) at -65 mV by 68+/-41% (n=5) and 69+/-50% (n=5), respectively. Actions of both agents were reversible. The increase in I(f) appeared to result from a change in maximal conductance and not a shift in the voltage dependence of activation. CONCLUSIONS: These observations provide, for the first time, direct electrophysiological support for the chronotropic actions of PTH and PTHrP. They suggest that classic hormones and paracrine factors can have multiple functions and that in the case of PTH and PTHrP, a newly recognized action is to alter automaticity directly. 相似文献
46.
Potential integrals for uniform and linear source distributions on polygonal and polyhedral domains 总被引:23,自引:0,他引:23
Wilton D. Rao S. Glisson A. Schaubert D. Al-Bundak O. Butler C. 《Antennas and Propagation, IEEE Transactions on》1984,32(3):276-281
Formulas for the potentials due to uniform and Linearly varying source distributions defined on simply shaped domains are systematically developed and presented. Domains considered are infinite planar strips, infinite cylinders of polygonal cross sections, planar surfaces with polygonal boundaries, and volumetric regions with polyhedral boundaries. The expressions obtained are compact in form and their application in the numerical solution of electromagnetics problems by the method of moments is illustrated. 相似文献
47.
48.
49.
Ilias Soumpasis Lis Alban Francis Butler 《Food research international (Ottawa, Ont.)》2012,45(2):1139-1148
Human salmonellosis is an important food-borne disease and S. Typhimurium is the most common serotype attributed to pork products. Under a farm-to-fork strategy, reducing the levels of Salmonella-positive pigs entering the slaughterhouse is an important goal. A framework model was developed, where the effect of dynamic (infection characteristics) and non-dynamic (cleanness and disinfection, biosecurity measures, etc.) factors were considered. Four baseline scenarios were created, corresponding to different levels associated with national Salmonella monitoring programs, and sensitivity analyses were run for the non-dynamic factors. Moreover, the option of vaccination was incorporated into the model, in order to provide with a tool for the formulation of an optimum vaccination strategy depending on the characteristics of the vaccine. 相似文献
50.