首页 | 官方网站   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   475篇
  免费   34篇
工业技术   509篇
  2024年   3篇
  2023年   13篇
  2022年   20篇
  2021年   31篇
  2020年   20篇
  2019年   31篇
  2018年   39篇
  2017年   25篇
  2016年   25篇
  2015年   14篇
  2014年   24篇
  2013年   31篇
  2012年   22篇
  2011年   45篇
  2010年   20篇
  2009年   22篇
  2008年   11篇
  2007年   10篇
  2006年   12篇
  2005年   7篇
  2004年   6篇
  2003年   5篇
  2002年   6篇
  2001年   5篇
  2000年   2篇
  1999年   5篇
  1998年   4篇
  1997年   5篇
  1996年   4篇
  1995年   6篇
  1994年   1篇
  1993年   1篇
  1992年   6篇
  1991年   2篇
  1990年   3篇
  1989年   4篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1982年   3篇
  1981年   2篇
  1980年   1篇
  1979年   1篇
  1978年   2篇
  1972年   2篇
  1971年   2篇
  1970年   2篇
  1967年   1篇
排序方式: 共有509条查询结果,搜索用时 93 毫秒
71.
72.
Relations between marital aggression (psychological and physical) and children's health were examined. Children's emotional insecurity was assessed as a mediator of these relations, with distinctions made between marital aggression against mothers and fathers and ethnicity (African American or European American), socioeconomic status, and child gender examined as moderators of effects. Participants were 251 community-recruited families, with multiple reporters of each construct. Aggression against either parent yielded similar effects for children. Children's emotional insecurity mediated the relation between marital aggression and children's internalizing, externalizing, and posttraumatic stress disorder symptoms. No differences were found in these pathways for African American and European American families or as a function of socioeconomic status or child gender. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
73.
Objective: The purpose of this study was to determine possible relations between the quality and amount of children's sleep and cortisol in healthy children. Design: Children's sleep was monitored with actigraphs for 7 nights. Children came to the laboratory to provide saliva samples, which were used to assess cortisol. Children reported on their sleepiness and sleep/wake problems. Sixty-four healthy children participated (M = 8.75 years; SD = .55). Main Outcome Measures: Self-reported sleepiness and sleep/wake problems, actigraphy-measured total sleep minutes, sleep efficiency, minutes awake after sleep onset, and sleep activity, and afternoon cortisol levels. Results: After controlling for demographic variables and child characteristics, higher levels of cortisol were related to increased subjective sleep problems and objective measures of shorter sleep duration and poorer sleep quality. Conclusion: These findings are of importance for understanding critical facets of children's health and well-being, and are noteworthy given the high prevalence of sleep disruptions in otherwise normally developing children in the United States. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
74.
The Occupational Safety and Health Administration's (OSHA's) Process Safety Management (PSM) regulation was promulgated in 1992. The U.S. Environmental Protection Agency's (EPA's) corresponding Risk Management Program (RMP) rule followed in 1996. Both programs include requirements for triennial compliance audits. Effective compliance audits are critical in identifying program weaknesses and ensuring the safety of facility personnel and the surrounding public. Large companies with corporate and facility health, safety, and environmental groups typically have the resources and experience to conduct audits internally, either through a corporate audit team or the sharing of personnel between multiple facilities. Small to medium sized businesses frequently do not have the expertise or the resources to perform compliance audits, and rely on third-party consultants to provide these services. This paper will discuss the observations of the authors in performing audits and working with PSM/RMP programs across a number of market sectors (e.g. chemical, petrochemical, pharmaceutical, food and beverage, water treatment), including effective practices, hurdles to successful implementation and execution of programs, and typical program shortcomings. The paper will also discuss steps to improve the audit process and increase effectiveness whether performed by a third party or internally.  相似文献   
75.
Benzoxazolinone detoxification is similar in plants grown under sulfur deficiency conditions and in control plants grown with an optimal S supply. However, when S-deficient plants were treated with metolachlor before benzoxazolin-2(3H)-one (BOA) incubation, detoxification was reduced, as indicated by a lower accumulation of the detoxification products BOA-6-O-glucoside and glucoside carbamate and by a loss of BOA-6-OH glucosyltransfease activity. Root colonizing microorganisms and the endophytic fungus Fusarium verticillioides participated in benzoxazolinone detoxification by converting the compound to 2-acetamidophenol (AAP) or O-hydroxyphenyl malonamic acid (OHPMA), a process accompanied by the appearance of phenoxazinone. Maize roots, however, absorbed AAP and OHPMA only in traces. Absorbed traces of OHPMA stimulated maize radicle growth, and traces of AAP stimulated cress. Phenoxazinone inhibited the growth of cress radicles at concentrations higher than 500 μM, whereas maize radicles were hardly affected. F. verticillioides did not convert benzoxazolinone to any known microbial degradation product when the medium of maize seedlings was inoculated with the fungus under sterile condition. Plant–fungus interactions seem to be important in plant survival of allelopathic attacks. This study points to a complicated network of allelopathic interactions that are influenced by biotic and abiotic factors, including herbicides.  相似文献   
76.
The human gut microbiota regulates estrogen metabolism through the “estrobolome,” the collection of bacterial genes that encode enzymes like β-glucuronidases and β-glucosidases. These enzymes deconjugate and reactivate estrogen, influencing circulating levels. The estrobolome mediates the enterohepatic circulation and bioavailability of estrogen. Alterations in gut microbiota composition and estrobolome function have been associated with estrogen-related diseases like breast cancer, enometrial cancer, and polycystic ovarian syndrome (PCOS). This is likely due to dysregulated estrogen signaling partly contributed by the microbial impacts on estrogen metabolism. Dietary phytoestrogens also undergo bacterial metabolism into active metabolites like equol, which binds estrogen receptors and exhibits higher estrogenic potency than its precursor daidzein. However, the ability to produce equol varies across populations, depending on the presence of specific gut microbes. Characterizing the estrobolome and equol-producing genes across populations can provide microbiome-based biomarkers. Further research is needed to investigate specific components of the estrobolome, phytoestrogen-microbiota interactions, and mechanisms linking dysbiosis to estrogen-related pathology. However, current evidence suggests that the gut microbiota is an integral regulator of estrogen status with clinical relevance to women's health and hormonal disorders.  相似文献   
77.
Palm leaves as a woody lignocellulose, together with polystyrene, were used to produce composites. Chemithermal mechanical pulps (CTMP) were obtained from palm leaves under alkaline or acidic conditions. Appropriate bending strength was obtained from palm leaves and their CTMP pulps prepared under neutral or acidic conditions. The bulky fibers resulted from the alkaline pulps lead to composites of low bending strength. Thus, the cooking conditions of the palm leaves to obtain CTMP pulp play an important role on the properties of the composites. The nonbulky fibers lead to the formation of trapped pockets air as the number of the hydrogen bond are few. The presence of these air pockets allows the polystyrene solution to enter forming bonding between the interfaces. It is also found that the lower the density of the composites, the lower the internal bond strengths. The chemical constituents of the CTMP pulps, as well as the yields of the pulps, may influence the properties of the composites. Increasing the percentage of polystyrene in the composites, the mechanical properties increased. The water uptake and the swellability decreased until 20% polystyrene concentration and then levelled off. The thickness and density behaved the same. However, the type of substrate of the composite and the weight fraction are the important factors in determining the properties of the composites. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 845–855, 1998  相似文献   
78.
Growth of Listeria monocytogenes in ready-to-eat fish products such as cold-smoked salmon is an important food safety issue. The objective of this study was to evaluate the antilisterial activity of potassium lactate (PL) in combination with sodium acetate (SA) or sodium diacetate (SDA) in cold-smoked salmon and to determine whether these compounds could be incorporated easily into the formulations and technology currently used by processors. A commercial brine injector was used to inject salmon filets with either saturated saline brine or saturated saline brine supplemented with combinations of PL and SA (PURASAL Opti.Form PA 4) or PL and SDA (PURASAL Opti.Form PD 4). In the brine-injected cold-smoked salmon, 2.1% (water phase) PL and 0.12% (water phase) SDA delayed the growth of L. monocytogenes for up to 42 days of vacuum-packaged storage at 10 degrees C. Storage at 25 degrees C for 6 h resulted in only a 1-log CFU/g increase in L. monocytogenes. Treatments with lower concentrations of PL and SDA or similar concentrations of PL and SA resulted in an extended lag phase and slower growth of L. monocytogenes. It was not possible to incorporate more than 2% (water phase) PL while ensuring a minimum of 3% (water phase) NaCl in the finished product because PL decreased the solubility of NaCl. Sensory analyses revealed that the preservatives did not negatively affect flavor or odor. The combination of PL and SDA is therefore a viable technology for preventing L. monocytogenes growth on cold-smoked salmon.  相似文献   
79.
Although property is a basic ingredient of planning, its repercussions on the profession have rarely been considered. Building on the critical analysis of property, I argue that planning is giving in to the “property effect,” the unquestioned assumption that natural and built landscapes are propertied. Looking specifically at one case-study of land-use planning in Tibneen (Lebanon), I show planning interventions replicate inequalities embedded in property relations, maintain the dominance of propertied representation of the landscape, and limit possible claims over natural and built landscapes to those formulated within the framework of the ownership model. Consequently, land-use planning determines the possible futures of particular towns and regions through the institutional structures of the property regimes in place and within the historically and geographically contingent political-economies where these regimes operate.  相似文献   
80.
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-23

京公网安备 11010802026262号