全文获取类型
收费全文 | 2907篇 |
免费 | 63篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 30篇 |
化学工业 | 467篇 |
金属工艺 | 38篇 |
机械仪表 | 80篇 |
建筑科学 | 119篇 |
矿业工程 | 5篇 |
能源动力 | 67篇 |
轻工业 | 193篇 |
水利工程 | 22篇 |
石油天然气 | 9篇 |
无线电 | 241篇 |
一般工业技术 | 427篇 |
冶金工业 | 934篇 |
原子能技术 | 46篇 |
自动化技术 | 295篇 |
出版年
2021年 | 26篇 |
2020年 | 22篇 |
2019年 | 28篇 |
2018年 | 35篇 |
2017年 | 30篇 |
2016年 | 32篇 |
2015年 | 41篇 |
2014年 | 40篇 |
2013年 | 113篇 |
2012年 | 72篇 |
2011年 | 87篇 |
2010年 | 81篇 |
2009年 | 76篇 |
2008年 | 100篇 |
2007年 | 103篇 |
2006年 | 74篇 |
2005年 | 74篇 |
2004年 | 73篇 |
2003年 | 63篇 |
2002年 | 64篇 |
2001年 | 59篇 |
2000年 | 62篇 |
1999年 | 72篇 |
1998年 | 228篇 |
1997年 | 159篇 |
1996年 | 110篇 |
1995年 | 67篇 |
1994年 | 62篇 |
1993年 | 63篇 |
1992年 | 43篇 |
1991年 | 39篇 |
1990年 | 32篇 |
1989年 | 41篇 |
1988年 | 40篇 |
1987年 | 29篇 |
1986年 | 31篇 |
1985年 | 41篇 |
1984年 | 42篇 |
1983年 | 34篇 |
1982年 | 31篇 |
1981年 | 50篇 |
1980年 | 23篇 |
1979年 | 29篇 |
1978年 | 28篇 |
1977年 | 53篇 |
1976年 | 63篇 |
1975年 | 30篇 |
1974年 | 18篇 |
1973年 | 31篇 |
1972年 | 20篇 |
排序方式: 共有2973条查询结果,搜索用时 15 毫秒
11.
Tobin David L.; Johnson Craig; Steinberg Stacey; Staats Marian; Dennis Amy Baker 《Canadian Metallurgical Quarterly》1991,100(1):14
Investigated a multifactorial approach to the assessment of bulimia nervosa by means of hierarchical factor analysis. 245 bulimia nervosa patients and 68 patients with either anorexia nervosa or eating disorders not otherwise specified were administered a self-report battery that was organized into 21 dimensions relevant to eating disorder patients. When dimensions from this battery were subjected to hierarchical factor analysis, support for bulimia nervosa as a unique diagnostic category was obtained. However, the emergence of 3 secondary factors and 6 primary factors suggests that bulimia nervosa can also be described more complexly. The emergence of a multifactorial model of bulimia nervosa that incorporates several existing unidimensional models suggests the potential for both divergent and complicated clinical presentation in bulimia nervosa patients. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
12.
C.J. Campbell S.K. Smoukov K.J.M. Bishop E. Baker B.A. Grzybowski 《Advanced materials (Deerfield Beach, Fla.)》2006,18(15)
The inside cover shows a hexagonal array of convex microlenses etched directly into glass using a reaction‐diffusion process initiated from a hydrogel stamp. The technique, reported by Grzybowski and co‐workers on p. 2004, allows for direct printing of complex microarchitectures into a variety of materials with sub‐micrometer resolution. The images were generated by longtime exposure of slowly rotating patterns. Cover design by Christopher J. Campbell. 相似文献
13.
Piasecki Thomas M.; Jorenby Douglas E.; Smith Stevens S.; Fiore Michael C.; Baker Timothy B. 《Canadian Metallurgical Quarterly》2003,11(4):276
Five parameters of postcessation smoking withdrawal variability derived from clinical data (T. M. Piasecki, D. E. Jorenby, S. S. Smith, M. C. Fiore, & T. B. Baker, 2003a, 2003b) were predicted from baseline measures and pharmacotherapy assignment. Smokers who were more dependent, older, and high in negative affect reported more severe withdrawal. Women, heavier smokers, and those with a history of depression reported more variable symptoms. Smokers treated with nicotine patch, bupropion, or both reported less severe withdrawal than did those given placebo, but medication did not affect the slope of symptoms over time, day-to-day variability of symptoms, or the size of acute changes in symptoms associated with lapses to smoking. Prior research has shown that these symptom facets predict later relapse: thus, current pharmacotherapies may aid cessation by diminishing withdrawal severity, but they do not affect all clinically important aspects of withdrawal. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
14.
We evaluated the effect of halothane anesthesia on the motility of the sphincter of Oddi and simultaneous transsphincteric flow in Australian Brush-tailed possums (Trichosurus vulpecula). Halothane levels in the range of 0.25 to 2% were administered and decreased transsphincteric flow in a dose-dependent manner. Sphincter of Oddi basal pressure was higher than normal, but not in a dose-dependent manner. Additionally, halothane anesthesia influenced the sphincter of Oddi motility by decreasing the motility index (mean amplitude multiplied by frequency of contractions). This decrease was dose dependent. These findings indicate that sphincter of Oddi basal pressure is a major component of sphincter of Oddi motility responsible for regulating transsphincteric flow in this species. For studies of the sphincter of Oddi motility in anesthetized Australian Brush-tailed possums, we recommend anesthetic induction with ketamine (50 mg/kg, i.m.) and the inspired halothane level should not exceed 0.75% during the study period, as the effects we have demonstrated were most evident at levels greater than 0.75%. If higher halothane levels are required to maintain satisfactory anesthesia, an alternative anesthetic agent should be considered. 相似文献
15.
16.
17.
Steven S Fu Miles McFall Andrew J Saxon Jean C Beckham Timothy P Carmody Dewleen G Baker Anne M Joseph 《Nicotine & tobacco research》2007,9(11):1071-1084
We conducted a systematic review of what is known about the relationship between post-traumatic stress disorder (PTSD) and smoking to guide research on underlying mechanisms and to facilitate the development of evidence-based tobacco treatments for this population of smokers. We searched Medline, PsychINFO, and the Cochrane Central Register of Controlled Trials and identified 45 studies for review that presented primary data on PTSD and smoking. Smoking rates were high among clinical samples with PTSD (40%-86%) as well as nonclinical populations with PTSD (34%-61%). Most studies showed a positive relationship between PTSD and smoking and nicotine dependence, with odds ratios ranging between 2.04 and 4.52. Findings also suggest that PTSD, rather than trauma exposure itself, is more influential for increasing risk of smoking. A small but growing literature has examined psychological factors related to smoking initiation and maintenance and the overlapping neurobiology of PTSD and nicotine dependence. Observational studies indicate that smokers with PTSD have lower quit rates than do smokers without PTSD. Yet a few tobacco cessation treatment trials in smokers with PTSD have achieved quit rates comparable with controlled trials of smokers without mental disorders. In conclusion, the evidence points to a causal relationship between PTSD and smoking that may be bidirectional. Specific PTSD symptoms may contribute to smoking and disrupt cessation attempts. Intervention studies that test behavioral and pharmacological interventions designed specifically for use in patients with PTSD are needed to reduce morbidity and mortality in this population. 相似文献
18.
Most (98%) of the fat in human milk is present as triglycerides. This paper describes the use of a clarification procedure that enables the level of human milk fat to be determined by measurement of glycerol released by enzymic hydrolysis of triglycerides. The method requires only 10-50 microliters milk, thus presenting a possible technique for work with small mammals, and is suitable for use with autoanalysers, permitting rapid sample throughput. 相似文献
19.
A novel method for the crosslinking of poly(ethylene terephthalate) fibers is described using 1,6‐hexanedisulfonyl azide, 1,3‐benzenedisulfonyl azide, and 2,6‐naphthalenedisulfonyl azide. The azides are diffused into poly(ethylene terephthalate) fibers (Dacron) from perchloroethylene solution, and the fibers are heat treated to bring about decomposition of the sulfonyl azide and give rise to crosslinking. A study is made of the mechanical and thermal properties of the resultant fibers, which are changed considerably in comparison to the untreated fiber. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1517–1527, 2002 相似文献
20.
“Study of a Numerically Modeled Severe Storm” is a well known animation within the scientific visualization community. The visualization is among the best of its genre, featuring full storyboarding, well chosen representations, high quality rendering, and professional narration. We recently revisited the thunderstorm to consider what we would do differently if we were to make that video again. We wanted to demonstrate several principles of effective information presentation, drawing from the fields of graphic design and visual perception. Our purpose was not to find fault with bad visualization. Rather, we wanted to study how to make a good thing better. The original video was produced using the modeling, animation, and rendering capabilities of Wavefront's Advanced Visualizer. To facilitate comparison, we did most of the current work with the same software. However, many points discussed here apply to interactive visualization tools as well. The original visualization and our revised version are both based on data generated by a simulation run on a Cray supercomputer at NCSA. The simulation models the genesis and lifetime of a severe storm by solving a set of time dependent equations over a collection of regularly spaced grid points in a three dimensional rectangular space 相似文献