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   165篇
  免费   1篇
工业技术   166篇
  2017年   2篇
  2010年   2篇
  2009年   2篇
  2008年   3篇
  2006年   2篇
  2005年   5篇
  2004年   3篇
  2003年   2篇
  2002年   3篇
  2000年   1篇
  1999年   2篇
  1998年   17篇
  1997年   12篇
  1996年   8篇
  1995年   4篇
  1994年   1篇
  1993年   1篇
  1992年   2篇
  1991年   2篇
  1990年   2篇
  1989年   1篇
  1988年   4篇
  1987年   3篇
  1986年   2篇
  1985年   3篇
  1984年   4篇
  1983年   3篇
  1982年   3篇
  1981年   2篇
  1980年   4篇
  1979年   4篇
  1978年   3篇
  1977年   7篇
  1976年   13篇
  1975年   2篇
  1974年   3篇
  1973年   3篇
  1971年   2篇
  1969年   1篇
  1964年   3篇
  1963年   2篇
  1962年   1篇
  1961年   2篇
  1960年   3篇
  1959年   1篇
  1958年   1篇
  1957年   3篇
  1956年   1篇
  1955年   1篇
  1954年   1篇
排序方式: 共有166条查询结果,搜索用时 93 毫秒
61.
Reports an error in "Agreement of parent and child reports of trauma exposure and symptoms in the early aftermath of a traumatic event" by Carla Smith Stover, Hilary Hahn, Jamie J. Y. Im and Steven Berkowitz (Psychological Trauma: Theory, Research, Practice, and Policy, 2010[Sep], Vol 2[3], 159-168). The article contained an incorrect DOI. The correct DOI is as follows: http://dx.doi.org/10.1037/a0019156. The online version has been corrected. (The following abstract of the original article appeared in record 2010-19144-001.) Exposure to violence and potentially traumatic events (PTEs) is a common experience among children and youth. The assessment of necessary intervention relies upon parental acknowledgment of exposure and recognition of their child's distress. Early interventions and treatment are most effective when parents are aware of the nature of the traumatic exposure, understand their child's symptomatic response, and are intimately involved in the treatment process. The present study investigated concordance between parents and exposed children on child trauma history, the subjective report of the impact of the traumas experienced, and presence of posttraumatic stress disorder (PTSD) symptoms. Agreement between parent and child report of traumas experienced was nonsignificant for serious accidents, separation from significant others, and physical assaults. Nonsignificant agreement was also found for avoidance and hyperarousal symptoms of PTSD. Correlations were not significant between parent and child report of the impact of traumas both at the time of the incident and at the time of the interview. Recommendations are suggested for helping parents improve their capacity to understand the potential impact of exposure on the child's psychological functioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
62.
In this essay we consider the relationship between journalists and news sources within the social context of communities and their newspapers. We portray these groups as interpretive communities, where shared meanings develop through on-going social interaction. We draw on literature related to news making, news sources, and community pluralism, concluding that the relationship between journalists and news sources is shaped by the preferred meanings of a community's interpretive groups, including journalists and their news organizations. We apply examples from interviews with journalists and news sources to illustrate and contextualize the discussion.  相似文献   
63.
Coordinated bursts of leg motoneuron activity were evoked in locusts with deefferented legs by tactile stimulation of sites that evoke grooming behavior. This suggests that insect thoracic ganglia contain central pattern generators for directed leg movements. Motoneuron recordings were made from metathoracic and mesothoracic nerves, after eliminating all leg motor innervation, as well as all input from the brain, subesophageal ganglion, and prothoracic ganglion. Strong, brief trochanteral levator motoneuron bursts occurred, together with silence of the slow and fast trochanteral depressor motoneurons and activation of the common inhibitor motoneuron. The metathoracic slow tibial extensor motoneuron was active in a pattern distinct from its activity during walking or during rhythms evoked by the muscarinic agonist pilocarpine. Preparations in which the metathoracic ganglion was isolated from all other ganglia could still produce fictive motor patterns in response to tactile stimulation of metathoracic locations. Bursts of trochanteral levator and depressor motoneurons were clearly coordinated between the left and right metathoracic hemiganglia and also between the mesothoracic and the ipsilateral metathoracic ganglia. These data provide clear evidence for centrally generated interlimb coordination in an insect.  相似文献   
64.
Isothermal annealing at 500 °C for various lengths of time after rapid quenching from 900 °C results in different degrees of ordering in Ni2Cr. Tensile specimens of disordered and ordered Ni2Cr were subjected to hydrogen embrittling and nonembrittling environments before and during tensile testing. The hydrogen embrittlement susceptibility was determined by reduction-in-area losses (RA loss) after failure. The results of the tensile tests indicated that the disordered alloy and highly ordered alloy were the most susceptible to hydrogen embrittlement. The RA loss in each case was approximately 70 pct. The tests revealed a minimum susceptibility to hydrogen embrittlement between 40 and 50 pct order. The fracture surfaces of the specimens, as examined by scanning electron microscopy, showed that the extent of embrittlement is correlated with the amount of intergranular failure. The mechanisms for failure in Ni2Cr appear to depend upon the extent of aging in the alloy.  相似文献   
65.
In-discharge reaction of coal with nitrogen/hydrogen mixtures rather than nitrogen alone raises rates of hydrogen cyanide generation by a factor of 10–50, and makes hydrogen cyanide account for ≈70–90% of the total product-gas volume. From these results and parallel tests with a pure carbon, it is concluded that enhanced formation of hydrogen cyanide is controlled by transient hydrogenation of aromatic carbon and consequent creation of additional (non-aromatic) reaction centres which can be abstracted by N*.  相似文献   
66.
Examines, in historical terms, the differences between the leaders of the handicapped rights (HRs) movement and leaders of the vocational rehabilitation VR program. VR was born in the 1920's and was dominated by the emerging science of psychology. HR activists came to political maturity in the 1960's and adopted a civil-rights ideology. It is suggested that both the professional and the civil rights outlook have their share of contradictions and that these contradictions need to be understood before they can be unraveled. (4 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
67.
Contractile responses to norepinephrine, serotonin and potassium chloride were determined in vitro for aortas from rats 1, 2, 3 and 12 months of age. Responses were measured under conditions of optimum length (3 cm) and resting tension (1 g). Aortic response to a maximum concentration of norepinephrine was greatest for vessels from 3-month-old rats. For all three agonists, aortas from 12-month-old rats contracted less than aortas from 2-month-old rats. The role of calcium in aortic contraction also varied with age. For rats 1-2 months of age, serotonin and potassium chloride-induced contractions were highly dependent on extracellular calcium, while norepinephrine-induced contraction showed only a slight dependence on extracellular calcium. In 12-month-old rats, all agonists were dependent on extracellular calcium for contraction. For serotonin and norepinephrine, the ability of muscle to contract in calcium-free media was decreased with age. Although the mechanism for such an altered dependence of aortic contraction on calcium has not been established, it is proposed that the utilization of extracellular calcium for contraction is not only agonist- but also age-dependent.  相似文献   
68.
Amonafide is a new imide derivative of naphthalic acid. The drug had demonstrated significant activity in preclinical studies and some activity in Phase I trials. The drug is extensively metabolized and detected in plasma and urine. Its toxicity has previously been correlated to the formation of an active metabolite, N-acetyl-amonafide. Amonafide was chosen for inclusion in the Cancer and Leukemia Group B (CALGB) master metastatic breast cancer protocol. CALGB 8642 randomizes previously untreated metastatic breast cancer patients either to one of several Phase II agents given for up to four cycles and then followed by standard cyclophosphamide-doxorubicin-5-fluorouracil, or to immediate treatment with standard cyclophosphamide-doxorubicin-5-fluorouracil. The end point of CALGB 8642 is to assess the difference in survival, toxicity, and overall response when limited exposure to Phase II agents precedes standard chemotherapy. This report deals only with amonafide as a Phase II agent. Comparisons with the cyclophosphamide-doxorubicin-5-fluorouracil arm will not be addressed. Patients had to have histologically documented measurable breast cancer and a performance status of 0-1. Patients could not have had prior chemotherapy for metastatic disease. Prior adjuvant chemotherapy was permitted. Patients could not have visceral crisis. Amonafide was given at 300 mg/m2/day i.v. for 5 days, and repeated at 21-day intervals for a maximum of four cycles. Escalation and reduction in dose was mandated dependent on hematotoxicity or lack thereof. Toxicity was primarily hematological and bimodal: 32% had grade 3 or 4 leukopenia and 24% had grade 3 or 4 thrombocytopenia; 22% had no leukopenia and 44% had no thrombocytopenia. The response rate was 18%, including one complete response. When response was analyzed by hematological toxicity, there was a 35.7% response if patients had leukopenia grade 3/4 (versus 8.3%, P = 0.08). There was a 50% response if patients had thrombocytopenia grade 3/4 (versus 7.1%, P = <0.01). We conclude that amonafide is somewhat active in previously untreated breast cancer patients. There may be a steep dose-response curve, based on the significant correlation between myelosuppression and response. Rates of responses in patients adequately dosed (i.e., with significant hematotoxicity) with amonafide ranged from 35 to 50%. Further studies will incorporate individualized dosing based on pretreatment acetylator phenotyping.  相似文献   
69.
Borderline ovarian tumors (BOTs), or ovarian tumors of low malignant potential, represent a distinct category of epithelial ovarian neoplasms that have a clinically more favorable outcome than invasive epithelial ovarian cancer. Histologically, BOTs and invasive ovarian carcinomas both show cellular proliferation and pleomorphism, but unlike invasive ovarian carcinomas, BOTs lack stromal invasion. Although serous BOTs are frequently confined to a single ovary at the time of diagnosis, bilateral or extra-ovarian spread occurs in 30-40% of cases. The purpose of this study is to determine whether bilateral or extraovarian serous borderline lesions are metastatic sites from the original tumor, or represent separate primary tumors. DNA specimens from multiple tumor sites and normal tissue controls were obtained in eight women with bilateral or extra-ovarian serous borderline tumors. The pattern of loss of heterozygosity at the androgen receptor locus on the X chromosome was evaluated in the multiple tumor sites. In addition, the pattern of X-chromosome inactivation was determined using HpaII restriction endonuclease digestion, followed by PCR amplification of the androgen receptor locus. Multifocality was determined when alternate patterns of X-chromosome inactivation occurred. In two of the eight patients, the left and right ovarian tumor sites had different androgen receptor alleles inactivated, indicating that the bilateral tumors derived independently. In a third patient, the X inactivation pattern in the left ovarian tumor differed from the two peritoneal implants, suggesting that the implants were separate primary tumors, and not metastatic, from the left ovarian tumor. The remaining five patients had the same pattern of loss of heterozygosity and X inactivation in the tumor sites studied. These results suggest that bilateral and advanced stage serous BOTs may be multifocal in origin. This result is in contrast to invasive epithelial ovarian cancer, which has been shown to be unifocal in origin.  相似文献   
70.
OBJECTIVE: To develop reliable scale measures of factors most important to applicants when they select internal medicine residencies and to assess their validity by comparing scores from these measures with responses to open-ended questions. DESIGN: All 353 applicants ranked by the University of North Carolina at Chapel Hill (UNC-CH) for the 1988 National Residency Match Program received a questionnaire after submitting their match lists. First, they listed the three most important factors considered in ranking residency programs and starred the single most important factor out of the three. Then, they rated 41 items on a five-point Likert scale ranging from 1 (not important) to 5 (extremely important). SETTING: Categorical internal medicine residency program at an academic medical center. MEASUREMENTS AND MAIN RESULTS: 315 (88%) applicants responded to the survey. Three reliable scales, Interpersonal Issues (7 items, alpha = 0.78), Reputation (5 items, alpha = 0.77), and Work Issues (11 items, alpha = 0.89), were developed using exploratory factor analysis of applicants' responses to the 41 items. Applicants felt interpersonal issues were very important (mean score = 4.2 +/- 0.5), academic reputation was important (3.3 +/- 0.8), and work issues were less important (2.8 +/- 0.7). The differences between these scores were significant (F = 3.76, p < 0.05). The ratings for the top five items not in these scales also indicated that education and location were very important. These results were corroborated by applicants' responses to the open-ended request to list the three most important factors in ranking residencies. CONCLUSION: These findings suggest that work issues are important, but greater emphasis is placed on interpersonal issues, education, location, and a program's reputation when applicants select residency programs. Furthermore, this study provides evidence supporting the reliability and validity of the three scales.  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-23

京公网安备 11010802026262号