全文获取类型
收费全文 | 2463篇 |
免费 | 3篇 |
专业分类
电工技术 | 3篇 |
综合类 | 2篇 |
化学工业 | 20篇 |
金属工艺 | 2篇 |
机械仪表 | 3篇 |
建筑科学 | 11篇 |
能源动力 | 1篇 |
轻工业 | 6篇 |
水利工程 | 2篇 |
石油天然气 | 2篇 |
无线电 | 4篇 |
一般工业技术 | 10篇 |
冶金工业 | 2383篇 |
原子能技术 | 1篇 |
自动化技术 | 16篇 |
出版年
2022年 | 2篇 |
2021年 | 3篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2015年 | 3篇 |
2014年 | 1篇 |
2013年 | 12篇 |
2012年 | 4篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 12篇 |
2008年 | 2篇 |
2007年 | 3篇 |
2006年 | 4篇 |
2004年 | 1篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 76篇 |
1998年 | 698篇 |
1997年 | 406篇 |
1996年 | 251篇 |
1995年 | 142篇 |
1994年 | 147篇 |
1993年 | 149篇 |
1992年 | 34篇 |
1991年 | 32篇 |
1990年 | 46篇 |
1989年 | 66篇 |
1988年 | 40篇 |
1987年 | 37篇 |
1986年 | 26篇 |
1985年 | 24篇 |
1983年 | 3篇 |
1982年 | 11篇 |
1981年 | 13篇 |
1980年 | 18篇 |
1979年 | 2篇 |
1978年 | 7篇 |
1977年 | 54篇 |
1976年 | 113篇 |
1975年 | 1篇 |
1960年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有2466条查询结果,搜索用时 15 毫秒
51.
N Majumdar P Bhattacharya DC Biswas RK Choudhury DM Nadkarni A Saxena 《Canadian Metallurgical Quarterly》1995,51(6):3109-3115
52.
CONCEPTS AND ASSUMPTIONS of self-in-relation theory of women's development, as proposed by feminist scholars at the Stone Center in Wellesley, Massachusetts, are applied in this article. This theory was used as a framework to guide staff development and mentorship roles of advanced practice nurses. How the theory served to direct these roles and assisted in development of a professional practice model is discussed. Exemplars from the authors' practices and professional practice outcomes after 2 years of theory implementation are presented. 相似文献
53.
JF Richmond S Lu JC Santoro J Weng SL Hu DC Montefiori HL Robinson 《Canadian Metallurgical Quarterly》1998,72(11):9092-9100
DNA vaccination is an effective means of eliciting strong antibody responses to a number of viral antigens. However, DNA immunization alone has not generated persistent, high-titer antibody and neutralizing antibody responses to human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env). We have previously reported that DNA-primed anti-Env antibody responses can be augmented by boosting with Env-expressing recombinant vaccinia viruses. We report here that recombinant Env protein provides a more effective boost of DNA-initiated antibody responses. In rabbits primed with Env-expressing plasmids, protein boosting increased titer, persistence, neutralizing activity, and avidity of anti-Env responses. While titers increased rapidly after boosting, avidity and neutralizing activity matured more slowly over a 6-month period following protein boosting. DNA priming and protein immunization with HIV-1 HXB-2 Env elicited neutralizing antibody for T cell line-adapted, but not primary isolate, viruses. The most effective neutralizing antibody responses were observed after priming with plasmids which expressed noninfectious virus-like particles. In contrast to immunizations with HIV-1 Env, DNA immunizations with the influenza virus hemagglutinin glycoprotein did not require a protein boost to achieve high-titer antibody with good avidity and persistence. 相似文献
54.
55.
Stephan Kraft Giuliano Casale Diwakar Krishnamurthy Des Greer Peter Kilpatrick 《Software and Systems Modeling》2013,12(4):681-704
We propose simple models to predict the performance degradation of disk requests due to storage device contention in consolidated virtualized environments. Model parameters can be deduced from measurements obtained inside Virtual Machines (VMs) from a system where a single VM accesses a remote storage server. The parameterized model can then be used to predict the effect of storage contention when multiple VMs are consolidated on the same server. We first propose a trace-driven approach that evaluates a queueing network with fair share scheduling using simulation. The model parameters consider Virtual Machine Monitor level disk access optimizations and rely on a calibration technique. We further present a measurement-based approach that allows a distinct characterization of read/write performance attributes. In particular, we define simple linear prediction models for I/O request mean response times, throughputs and read/write mixes, as well as a simulation model for predicting response time distributions. We found our models to be effective in predicting such quantities across a range of synthetic and emulated application workloads. 相似文献
56.
The morbidity and mortality in short bowel syndrome are directly related to the length of the remaining small bowel and to the duration of total parenteral nutrition. We describe the successful salvage of an infant with extensive small bowel infarction for whom a new technique was used to preserve all viable mucosal surfaces. The infant, with gastroschisis, was found to have a tight volvulus of the extruded bowel and extensive small bowel ischemia at the time of delivery. Forty-eight hours after reduction of the volvulus and abdominal decompression, a second-look laparotomy was performed. Although only the terminal 13 cm of ileum was completely viable, 25% of the circumference of a further 23 cm of proximal jejunum/ileum was considered salvageable. After debridement of the dead tissue, the remaining gutter of jejunum was divided at its midpoint, and the two halves were anastomosed longitudinally to provide a "neojejunum" of 12 cm in length, which was anastomosed between the duodenum and terminal ileum. Full enteral feeding was tolerated from day 47. Although the neojejunum was excised on day 149, after becoming dilated and atonic, by that time the remaining small bowel had elongated to 30 cm. Because of the early institution of full enteral feeding, there were no long-term complications related to total parenteral nutrition. 相似文献
57.
OBJECTIVE: This study explored psychosocial and "environmental" correlates of childhood anxiety disorders. The study examined relationships among parental psychiatric symptomatology, perceived family environment, temperament, and self-competence in children with a DSM-III-R anxiety disorder. METHOD: A community sample of third through sixth graders was screened initially for symptoms of test anxiety. Those with high and low scores were administered the Anxiety Disorders Interview Schedule for Children. Three groups (childhood anxiety disorder, test-anxious only, and normal controls) were identified and compared on the psychosocial variables. RESULTS: Children with an anxiety disorder had greater impairment on the indices of perceived self-competence and temperamental flexibility than controls, with the test-anxious children showing intermediate, yet significant, levels of disturbance. There was a trend for children with an anxiety disorder to describe their families as less promoting of independence than the other groups. Finally, measures of parental psychiatric symptomatology revealed more obsessive-compulsive symptoms for the fathers of both the anxiety disorder and test-anxious children compared with controls. CONCLUSIONS: Results are consistent with previous findings suggesting the familial transmission of anxiety disorders and recent speculations regarding a relationship between behavioral inhibition, environmental control, and anxiety. Further research may isolate psychosocial and family environmental factors as instrumental treatment targets in the management of childhood anxiety disorders. 相似文献
58.
The classic hypoglossal transfer to the facial nerve is invariably followed by complications caused by tongue atrophy. In 1984, Terzis introduced the "baby-sitter" procedure which involved a formal cross-facial procedure, in addition to partial neurectomy of the hypoglossal nerve, and an end-to-side coaptation with the ipsilateral facial nerve. This reported study provides, for the first time, quantification of the number of hypoglossal motor fibers needed to successfully restore eye sphincter function, using an end-to-side coaptation with preservation of the tongue. Thirty adult Sprague-Dawley rats were divided into six groups: control, denervated, perineurial window, 20 percent partial neurectomy (PN), 40 percent PN, and 80 percent PN. The procedure involves interposing a nerve graft (saphenous) between the partially severed XII nerve and the upper zygomatic branch of the facial nerve. Evaluation of the behavioral data (blink reflex) revealed good-to-superb return of the blinking mechanism in the 40 percent group, without significant tongue atrophy. Electrophysiologic data in the 40 percent neurectomy group demonstrated superiority to the other groups. Quantitative axonal morphometry of the coaptation sites and graft, as well as motor end-plates of the orbicularis oculi muscle and tongue showed the 40 percent partial neurectomy group to be the optimal group. 相似文献
59.
P Brown L Cervenáková L McShane LG Goldfarb K Bishop F Bastian J Kirkpatrick P Piccardo B Ghetti DC Gajdusek 《Canadian Metallurgical Quarterly》1998,50(3):684-688
A 53-year-old man died of sporadic Creutzfeldt-Jakob disease (CJD) after a 1.5-year clinical course. Four and a half years later, his then 55-year-old widow died from CJD after a 1-month illness. Both patients had typical clinical and neuropathologic features of the disease, and pathognomonic proteinase-resistant amyloid protein ("prion" protein, or PrP) was present in both brains. Neither patient had a family history of neurologic disease, and molecular genetic analysis of their PrP genes was normal. No medical, surgical, or dietary antecedent of CJD was identified; therefore, we are left with the unanswerable alternatives of human-to-human transmission or the chance occurrence of sporadic CJD in a husband and wife. 相似文献
60.
MD Dake DC Miller RS Mitchell CP Semba KA Moore T Sakai 《Canadian Metallurgical Quarterly》1998,116(5):689-703; discussion 703-4
OBJECTIVE: Our goal was to determine whether endovascular stent-grafting is feasible and effective for patients with aneurysms of the descending thoracic aorta. METHODS: Starting in July 1992, we conducted a prospective, uncontrolled clinical trial in 103 patients (mean age 69 years [range 34-89 years]) who underwent endovascular treatment of aneurysms of the descending thoracic aorta using a custom-fabricated, self-expanding stent-graft device. Follow-up was 100% complete and averaged 22 months. Sixty-two patients (60%) were judged not to be reasonable candidates for a conventional "open" surgical procedure. RESULTS: Complete thrombosis of the aneurysm was ultimately achieved in 86 (83%) patients. The early mortality rate was 9% +/- 3% (+/- 70% CL). Multivariable analysis revealed that myocardial infarction or stroke was linked with a higher likelihood of early death (P = .001). Early serious complications included paraplegia in 3% +/- 2% and stroke in 7% +/- 3%. Actuarial survival estimates at 1 year and 2 years were 81% +/- 4% and 73% +/- 5% (+/- 1 SE), respectively; being judged not to be a surgical candidate portended a higher probability of death (P = .003). According to the intent-to-treat principle, "treatment failure" (including all late sudden unexplained deaths) occurred in 38 patients; 53% +/- 10% of patients were free from treatment failure at 3.7 years. Stent-graft related complications occurred commonly and were linked with several anatomic, technical, and patient-related risk factors. CONCLUSIONS: This 5-year clinical trial involving use of a "first generation" device indicates that endovascular stent-grafting of descending thoracic aortic aneurysms is feasible with acceptable medium-term results. More refined, commercially developed devices available today offer less traumatic and more precise stent-graft deployment; these major technical advantages, coupled with important lessons we have learned over time and better patient selection, should be associated with more salutary clinical results in the future. 相似文献