全文获取类型
收费全文 | 1066篇 |
免费 | 10篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 59篇 |
金属工艺 | 6篇 |
机械仪表 | 4篇 |
建筑科学 | 16篇 |
能源动力 | 1篇 |
轻工业 | 49篇 |
水利工程 | 4篇 |
石油天然气 | 23篇 |
无线电 | 17篇 |
一般工业技术 | 28篇 |
冶金工业 | 842篇 |
原子能技术 | 1篇 |
自动化技术 | 25篇 |
出版年
2021年 | 2篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 7篇 |
2015年 | 3篇 |
2014年 | 6篇 |
2013年 | 27篇 |
2012年 | 8篇 |
2011年 | 16篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2008年 | 11篇 |
2007年 | 5篇 |
2006年 | 10篇 |
2005年 | 9篇 |
2004年 | 10篇 |
2003年 | 17篇 |
2002年 | 9篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 25篇 |
1998年 | 258篇 |
1997年 | 161篇 |
1996年 | 121篇 |
1995年 | 52篇 |
1994年 | 49篇 |
1993年 | 39篇 |
1992年 | 12篇 |
1991年 | 15篇 |
1990年 | 14篇 |
1989年 | 18篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 12篇 |
1985年 | 13篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1980年 | 11篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 21篇 |
1976年 | 53篇 |
1975年 | 3篇 |
1973年 | 3篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1955年 | 1篇 |
1945年 | 1篇 |
排序方式: 共有1080条查询结果,搜索用时 0 毫秒
1.
FC Breedveld 《Canadian Metallurgical Quarterly》1997,141(15):717-719
Slow-acting antirheumatic drugs (SAARDs) are usually prescribed in rheumatoid arthritis only when non-steroid anti-inflammatory drugs can no longer suppress the inflammation or when articular damage is radiologically apparent. It was established recently that articular damage occurs in an early phase of RA. This damage is linked to subsequent disability; to prevent it is the purpose of SAARDs. In view of the short-term reduction of arthritis activity and improvement of function as well as the meanwhile established fact that the side effects of SAARDs are not different from those of other antirheumatic agents, SAARDs should be prescribed in an early phase of RA. 相似文献
2.
3.
4.
JF DeFrance S Sands FC Schweitzer L Ginsberg JC Sharma 《Canadian Metallurgical Quarterly》1997,9(4):283-293
The purpose of this article is to deliberate the moral and legal dilemma entailed in the weapon of the labour strike as a pressure tactic on the Israeli Finance Ministry regarding job slots, budgets and, in effect, violating the collective agreement signed by the nurses and impairing patients' treatment, as opposed to refraining from striking and suffering the heavy burden of work, the lack of trained personnel, low wages, and the inability to give patients proper, high quality treatment. 相似文献
5.
To study the effect of ischemia reperfusion injury on microvascular reactivity and tissue metabolism in skeletal muscle, a Sprague-Dawley rat cremaster muscle was prepared as a tourniquet ischemia model and subjected to 2 hr ischemia followed by 1 hr reperfusion to simulate the timing of ischemia during microvascular surgery. The dose-response curve of arteriolar reactivity to norepinephrine, lipid peroxidation, and ultrastructure of capillaries was determined in both the control and postischemic reperfusion stages. Judging from the results, we summarize our observations as follows: (1) Postischemic reperfusion significantly increased arteriolar reactivity to norepinephrine, in which the EC50 for vasoconstriction decreased in all three orders of arterioles. These results suggest that reperfusion could have impaired the vasodilation control mechanism, possibly being endothelium dependent. (2) Lipid peroxidation increased sixfold in the reperfusion group, suggesting that oxygen free radicals have produced significant tissue damage under the created conditions. (3) Significant endothelial damage in the capillaries shown by electron microscope observation supports these studies, indicating that ischemia/reperfusion in clinically transplanted skeletal muscles could cause significant damage to the tissue microcirculation both physiologically and metabolically. 相似文献
6.
Neudorf E.G. Kiguel D.L. Hamoud G.A. Porretta B. Stephenson W.M. Sparks R.W. Logan D.M. Bhavaraju M.P. Billinton R. Garrison D.L. 《Power Systems, IEEE Transactions on》1995,10(3):1667-1675
There is an emerging recognition that utility investments and other decisions that affect electric service reliability should be explicitly evaluated on the basis of their cost and benefit implications. A cost-benefit approach that quantifies the reliability benefits of alternatives in terms of the reduction in costs resulting from unserved energy enables the evaluation of generation and transmission capacity additions on a consistent, economic basis. This approach has been applied to two utility case studies. In a case study for Pacific Gas and Electric Company, it was used to evaluate three options for maintaining reliability in a major load center-two involving local generation, and the third, a new 230 kV transmission connection. In a case study for Duke Power Company, the approach was used to evaluate alternative designs for proposed additions to a transmission station. This paper describes the methodology and presents the two utility studies 相似文献
7.
Carlston Donal E.; Skowronski John J.; Sparks Cheri 《Canadian Metallurgical Quarterly》1995,69(3):420
Five experiments based on Carlston and Skowronski's (1994) relearning paradigm suggest that people spontaneously derive trait knowledge about actors from behaviors but that this knowledge may reflect either explicit trait inference processes or implicit actor–trait associations. Experiments 1 and 2 found that inference-instructed and control Ss showed equivalent savings in subsequent efforts to learn actor–trait pairs but not when instructed Ss initially inferred the wrong trait. Experiment 3 showed that savings were equivalent for stimuli from different sources, and Experiment 4 showed that savings effects persisted even when the target was only incidentally associated with a stimulus behavior. Finally, Experiment 5 suggests that after several days, even explicit trait inferences can become inaccessible to intentional retrieval, although the earlier experiments show that they continue to exert an implicit effect on learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
RW Sidwell DF Smee RP Warren JH Huffman BJ Gilbert RA Burger FC Pearson 《Canadian Metallurgical Quarterly》1993,20(4):279-292
ImuVert, a sterile preparation composed primarily of Serratia marcescens membrane vesicles and ribosomes, was significantly inhibitory to murine cytomegalovirus (MCMV) infections in BALB/c mice. Antiviral activity was manifested as increased survivor number and decreased recoverable virus titers in spleens, lungs and salivary glands. Treatments were intraperitoneal (i.p.) beginning 24 h pre, 4 h post- or 24 h post-virus inoculation and then repeated 4 days later. Doses of 5, 16 or 50 micrograms/mouse were effective; 160 micrograms/mouse, which caused host weight loss in toxicity controls, was not inhibitory to the infection. A single i.p. treatment of mice substantially augmented natural killer (NK) cell activity and increased total B-cells, while reducing total T- and T-helper cells. A late (48 h) decline in T-cell function and transient increases in B-cell function were observed in the treated animals. Serum interferon was not induced. Mice pretreated with anti-asialo GM1 antibody to reduce their NK cell populations, then infected with MCMV and treated with ImuVert were protected to the same degree as normal animals. Severe combined immunodeficient mice infected with MCMV and treated with ImuVert were not protected from the infection. These data suggest ImuVert to act by a mechanism other than NK cell activation in preventing MCMV infections. 相似文献
9.
In the 1960s the promise of the Brantigan lung reduction surgery was shattered when it was shown that the improvement in airway conductance drifted back towards the preoperative value over a period of 12 to 18 months. Since then there has been a marked improvement in our understanding of emphysema, its pathology, and techniques for obtaining images of the lung. In addition, reliable automated cardiopulmonary and physiologic testing, advances in critical care medicine, and new pharmacologic agents have improved patient care. Surgical techniques now allow better control of air leaks and access to anatomic regions not previously accessible. The combination of all of the above makes lung reduction surgery worth re-examining as a palliative procedure for severely symptomatic patients. Clearly, it is not a panacea but can in some cases produce dramatic improvements in symptomatology and quality of life. This article presents the available data describing potential mechanisms of improvement and clinical outcomes following lung reduction surgery. It also outlines areas that need further work, such as patient selection and surgical techniques. 相似文献
10.
1. Microstimulation is used to investigate how activity in the superior colliculus (SC) contributes to determining the properties of primate saccadic eye movements. The site of collicular stimulation, the duration of the stimulation train, and the frequency of the stimulation train are each varied to examine the relative contributions of the locus, duration, and level of collicular activity to determining saccade amplitude, direction, duration, and velocity. 2. For any given site of stimulation, a relationship between movement amplitude and train duration can be demonstrated. Movement amplitude is a monotonically increasing, but saturating, function of increasing train duration. The size of the largest movement is dictated by the site of stimulation. Within the range over which amplitude can be modulated, movement offset is linked to the offset of the stimulation train. As a result, each decrement or increment in train duration produces a corresponding decrement or increment in movement duration. 3. The peak velocity of an evoked movement is influenced by the frequency of stimulation; a higher frequency of stimulation produces a movement of higher velocity. 4. The effects of train duration and frequency can be traded to produce movements that have comparable amplitudes but different dynamic characteristics; high-velocity movements of short duration and low-velocity movements of long duration can be produced by stimulating with high-frequency, short-duration, and low-frequency, long-duration trains, respectively. Across stimulation frequencies, the amplitude of an evoked movement is best related to the total number of pulses in the stimulation train. 5. Because it is possible to compensate for reduced velocity by increasing the duration of the stimulation train, the same site-specific maximum amplitude can be attained with different frequencies of stimulation. 6. Small, but significant, changes in movement direction occur as a result of varying train duration or train frequency. 7. The latency to movement onset (i.e., interval from stimulation onset to movement onset) depends upon the frequency of stimulation. A higher frequency of stimulation produces a movement of shorter latency. 8. These data demonstrate that both the site of stimulation and the parameters of stimulation contribute to determining the properties of a movement evoked from the primate SC. In doing so, they contradict the results of early microstimulation studies that suggest that the properties of eye movements evoked from the primate SC are determined solely by the site of stimulation. The findings conflict with the traditional view of collicular function that suggests that the collicular motor representation is purely anatomic. Rather, these data support a revised view whereby the locus, duration, and level of collicular activity contribute to determining the properties of a primate saccadic eye movement. According to this view, independent information relating to desired displacement and saccade velocity are extracted from the spatiotemporal profile of collicular activity. 相似文献