全文获取类型
收费全文 | 1079篇 |
免费 | 44篇 |
学科分类
工业技术 | 1123篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 34篇 |
2021年 | 47篇 |
2020年 | 30篇 |
2019年 | 24篇 |
2018年 | 20篇 |
2017年 | 32篇 |
2016年 | 26篇 |
2015年 | 27篇 |
2014年 | 43篇 |
2013年 | 57篇 |
2012年 | 54篇 |
2011年 | 76篇 |
2010年 | 65篇 |
2009年 | 47篇 |
2008年 | 79篇 |
2007年 | 59篇 |
2006年 | 64篇 |
2005年 | 61篇 |
2004年 | 43篇 |
2003年 | 28篇 |
2002年 | 30篇 |
2001年 | 14篇 |
2000年 | 24篇 |
1999年 | 14篇 |
1998年 | 19篇 |
1997年 | 18篇 |
1996年 | 14篇 |
1995年 | 11篇 |
1994年 | 9篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有1123条查询结果,搜索用时 15 毫秒
1.
2.
3.
Hitsman Brian; Borrelli Belinda; McChargue Dennis E.; Spring Bonnie; Niaura Raymond 《Canadian Metallurgical Quarterly》2003,71(4):657
The authors conducted a meta-analysis of published studies to (a) evaluate the premise that a history of major depression is associated with failure to quit smoking and (b) identify factors that moderate the relationship between history of depression and cessation outcome. Fifteen studies met the selection requirements and were coded for various study methodology and treatment characteristics. DSTAT was used to calculate individual study effect sizes, determine the mean effect size across studies. and test for moderator effects. No differences in either short-term (≤ 3 months) or long-term abstinence rates (≥ 6 months) were observed between smokers positive versus negative for history of depression. Lifetime history of major depression does not appear to be an independent risk factor for cessation failure in smoking cessation treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
5.
Melissa Kurtz 《Journal of Failure Analysis and Prevention》2007,7(3):175-178
Fuel system assemblies used on recreational watercraft failed after a short time in service in a seawater environment. Examination
of the assemblies revealed significant degradation of the polyacetal connectors of the wire subassemblies. Optical and microscopic
evaluations indicated the complete loss of connector material implying decomposition of the resin, along with mud-cracking
and a rough surface morphology signifying chemical attack. An elemental analysis performed on both an intact connector and
degraded connector suggested a potential chemical agent in the form of zinc chloride. At elevated temperatures, concentrated
zinc chloride solutions are known to decompose polyacetal resins. The source of the zinc chloride was established as corrosion
products that resulted during the dezincification of the internal brass connector through exposure to saltwater in the application. 相似文献
6.
Discusses common presenting complaints and those of emergent significance that have an organic etiology. The following categories are discussed: head, eyes, ears, throat, neck, cardiac, respiratory, gastrointestinal, genito-urinary, musculoskeletal, and neurologic complaints. It is suggested that many therapists lack adequate medical information to suspect the presence of organic problems when symptoms are indistinguishable from psychogenic/psychosomatic problems. (4 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
The present study examined whether siblings experience marital conflict differently and whether such differences, if present, were associated with differences in their adjustment. Self-report data about marital conflict, children's depressed mood, behavioral conduct, and externalizing problems were obtained from 122 sibling pairs (mean ages = 10 and 12 years) and their parents. Results indicated that siblings were significantly different in exposure to and appraisals of marital conflict. Differences in siblings' exposure to marital conflict were significantly correlated with differences in their depressed mood, behavioral conduct, and externalizing problems. Differences in siblings' feelings of self-blame for marital conflict were significantly correlated with differences in their depressed mood and behavioral conduct. Children who experienced more marital conflict than their siblings had more adjustment problems than their siblings. These results highlight the importance of studying siblings' unique experiences of marital conflict to better understand its impact on children's adjustment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
Children can express thoughts in gesture that they do not express in speech--they produce gesture-speech mismatches. Moreover, children who produce mismatches on a given task are particularly ready to learn that task. Gesture, then, is a tool that researchers can use to predict who will profit from instruction. But is gesture also useful to adults who must decide how to instruct a particular child? We asked 8 adults to instruct 38 third- and fourth-grade children individually in a math problem. We found that the adults offered more variable instruction to children who produced mismatches than to children who produced no mismatches--more different types of instructional strategies and more instructions that contained two different strategies, one in speech and the other in gesture. The children thus appeared to be shaping their own learning environments just by moving their hands. Gesture not only reflects a child's understanding but can play a role in eliciting input that could shape that understanding. As such, it may be part of the mechanism of cognitive change. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
Einstein Gilles O.; McDaniel Mark A.; Richardson Sarah L.; Guynn Melissa J.; Cunfer Allison R. 《Canadian Metallurgical Quarterly》1995,21(4):996
Past research has frequently failed to find age differences in prospective memory. This article tested the possibility that age differences would be more likely to emerge on a prospective memory task that was high in self-initiated retrieval. In the 1st experiment, participants were asked to perform an action every 10 min (a time-based task presumed to be high in self-initiated retrieval); in the 2nd experiment, participants were asked to perform an action whenever a particular word was presented (an event-based task presumed to be relatively low in self-initiated retrieval). Age differences were found with the time-based task but not with the event-based task. This pattern of age differences was again found in a 3rd experiment in which a new experimental procedure was used and the nature of the prospective memory task was directly varied. Generally, the results suggest that self-initiated retrieval processes are an important component of age-related differences across both retrospective and prospective memory tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
A series of statistical copolymers derived from 2‐(dimethylamino)ethyl methacrylate with four different hydrophobic comonomers (ethyl, butyl, cyclohexyl, and octyl methacrylates) have been prepared via conventional free radical copolymerization under bulk conditions. The copolymers have been subsequently modified, with 1,3‐propanesultone to yield the corresponding polysulfoproylbetaine derivatives. Those copolymers exhibiting the requisite aqueous solubility have been screened with respect to their antimicrobial activity against two common and notorious pathogens, namely Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). We show that certain copolymers do indeed exhibit antimicrobial activity. The extent of activity is related to the molecular characteristics of the materials such as the molar composition and structure of the hydrophobic comonomer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1036–1041, 2006 相似文献