首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   5675篇
  免费   227篇
  国内免费   9篇
电工技术   76篇
综合类   3篇
化学工业   1207篇
金属工艺   86篇
机械仪表   85篇
建筑科学   188篇
矿业工程   7篇
能源动力   137篇
轻工业   590篇
水利工程   63篇
石油天然气   16篇
无线电   381篇
一般工业技术   1024篇
冶金工业   1381篇
原子能技术   49篇
自动化技术   618篇
  2023年   35篇
  2022年   74篇
  2021年   116篇
  2020年   89篇
  2019年   83篇
  2018年   125篇
  2017年   95篇
  2016年   116篇
  2015年   76篇
  2014年   135篇
  2013年   310篇
  2012年   261篇
  2011年   326篇
  2010年   232篇
  2009年   242篇
  2008年   288篇
  2007年   281篇
  2006年   221篇
  2005年   208篇
  2004年   203篇
  2003年   183篇
  2002年   185篇
  2001年   117篇
  2000年   94篇
  1999年   95篇
  1998年   163篇
  1997年   122篇
  1996年   111篇
  1995年   94篇
  1994年   92篇
  1993年   91篇
  1992年   76篇
  1991年   55篇
  1990年   61篇
  1989年   63篇
  1988年   70篇
  1987年   57篇
  1986年   67篇
  1985年   68篇
  1984年   52篇
  1983年   49篇
  1982年   41篇
  1981年   48篇
  1980年   28篇
  1979年   35篇
  1978年   27篇
  1977年   34篇
  1976年   40篇
  1975年   18篇
  1974年   21篇
排序方式: 共有5911条查询结果,搜索用时 15 毫秒
51.
This article describes the psychological theories of the Holocaust survivors Bruno Bettelheim and Viktor Frankl. Both Bettelheim and Frankl claimed that their peculiar forms of psychotherapy, in the case of Bettelheim mileau therapy, and Frankl, logotherapy, were based on their survival. However, their radically different forms of psychotherapy, when at least elements of their camp experience was similar, suggests that their psychotherapies were based more upon the worldviews before their interment along with their need to work over the humiliation and profound victimization they experienced in the camps. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
52.
The present study estimated the unique contribution of self-efficacy to work-related performance controlling for personality (the Big 5 traits), intelligence or general mental ability, and job or task experience. Results, based on a meta-analysis of the relevant literatures, revealed that overall, across all studies and moderator conditions, the contribution of self-efficacy relative to purportedly more distal variables is relatively small. Within moderator categories, there were several cases in which self-efficacy made unique contributions to work-related performance. For example, self-efficacy predicted performance in jobs or tasks of low complexity but not those of medium or high complexity, and self-efficacy predicted performance for task but not job performance. Overall, results suggest that the predictive validity of self-efficacy is attenuated in the presence of individual differences, though this attenuation does depend on the context. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
53.
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   
54.
Causal learning requires integrating constraints provided by domain-specific theories with domain-general statistical learning. In order to investigate the interaction between these factors, the authors presented preschoolers with stories pitting their existing theories against statistical evidence. Each child heard 2 stories in which 2 candidate causes co-occurred with an effect. Evidence was presented in the form: AB→E; CA→E; AD→E; and so forth. In 1 story, all variables came from the same domain; in the other, the recurring candidate cause, A, came from a different domain (A was a psychological cause of a biological effect). After receiving this statistical evidence, children were asked to identify the cause of the effect on a new trial. Consistent with the predictions of a Bayesian model, all children were more likely to identify A as the cause within domains than across domains. Whereas 3.5-year-olds learned only from the within-domain evidence, 4- and 5-year-olds learned from the cross-domain evidence and were able to transfer their new expectations about psychosomatic causality to a novel task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
55.
The effects of 2 alternative modeling strategies (using multiple scenarios and combining negative and positive model displays) on outcomes of a behavior modeling training program were explored. Trainees (N?=?72) participated in a program on assertive communication structured to allow for a controlled experimental design that crossed scenario variability (1 vs multiple scenarios) with model display variability (positive model displays vs positive and negative model displays). Outcomes assessed included trainee reactions, learning, and retention and behavioral measures of reproduction and generalization. The effects of multiple scenarios were negligible, but the positive and negative combination of model displays had a significant positive effect on trainee generalization and a significant negative effect on reproduction. Implications for future modeling research and practice are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
56.
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   
57.
A computational study to examine the effects of parameter variation on debris cloud formation and perforation behavior in a simple sphere-plate impact situation is described. The parameters varied were impact velocity, thickness: diameter ratio, projectile-target material combination and number of plates. In particular, effects associated with changes from strength-dominated to hydrodynamic behavior were considered.  相似文献   
58.
Several boron-containing organosilicon polymers were synthesized from a sodium-coupling reaction of silicon and boron halides with and without alkyl halide in hydrocarbon solvents. The B–Si preceramic polymers were characterized using techniques such as IR, UV, and NMR spectrometry, gel permeation chromatography, elemental analysis, molecular weight measurement, and thermal analyses (TGA, DSC, DTA, and TMA). The chemical structures of the preceramic polymers were postulated based on the analytical results. Black ceramic materials were obtained from the precursor polymers upon thermal degradation at temperatures above 1000°C in an inert atmosphere. The precursor polymers had a ceramic yield of up to 70%. Thermogravimetric analysis of the ceramic material in air at a flow rate of 100 mL/min showed it was stable up to 1000°C with little weight gain or loss. Several methods were used to characterize the ceramic materials: XRD, solid NMR, high-temperature DTA, elemental analysis, and acid digestion. The analyses indicated that the ceramic materials comprised a mixture of silicon carbide (SiC), silicon borides (SiB4, SiB6), and amorphous Si–B–C ceramics, with small amounts of silica and free silicon.  相似文献   
59.
The classical capacitance-voltage measurement methods and the conductance technique which are frequently used to analyze the SiO2---Si system, are briefly introduced and critically evaluated. These measurement techniques are based on macroscopic device structures, average structure parameters are determined. Transient and random telegraph signal measurements, and charge pumping are now available as new methods to study the SiO2---Si interface in sub-μm device structures. These techniques permit to analyze single, individual traps in the interface. Traps in small devices are isolated. The capture rates are thermally activated by the Coulomb energy.  相似文献   
60.
A test method useful in determining the effects of polymer additives upon water carry-over (WCO) in water quenched, cast film extrusion is presented. Data from this test is obtained on film specimens based in a Spherilene process HDPE resin individually doped with 250 and 500 ppm of six various primary and secondary antioxidants and acid scavengers. Water contact angles and film surface tension data is also presented. The WCO test is reproducible and data may be applied to commercial production. Different additives that carry out the same function in the polymer may have greatly varying WCO properties; these differences are not detected by equilibrium goniometry.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号