全文获取类型
收费全文 | 2657篇 |
免费 | 5篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 50篇 |
金属工艺 | 7篇 |
机械仪表 | 21篇 |
建筑科学 | 6篇 |
能源动力 | 3篇 |
轻工业 | 38篇 |
水利工程 | 6篇 |
石油天然气 | 1篇 |
无线电 | 15篇 |
一般工业技术 | 54篇 |
冶金工业 | 2411篇 |
原子能技术 | 6篇 |
自动化技术 | 37篇 |
出版年
2022年 | 3篇 |
2021年 | 3篇 |
2019年 | 3篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 7篇 |
2014年 | 10篇 |
2013年 | 16篇 |
2012年 | 17篇 |
2011年 | 14篇 |
2010年 | 11篇 |
2009年 | 7篇 |
2008年 | 7篇 |
2007年 | 18篇 |
2006年 | 5篇 |
2005年 | 7篇 |
2004年 | 9篇 |
2003年 | 14篇 |
2002年 | 7篇 |
2001年 | 6篇 |
2000年 | 9篇 |
1999年 | 60篇 |
1998年 | 730篇 |
1997年 | 402篇 |
1996年 | 282篇 |
1995年 | 150篇 |
1994年 | 134篇 |
1993年 | 126篇 |
1992年 | 22篇 |
1991年 | 29篇 |
1990年 | 25篇 |
1989年 | 47篇 |
1988年 | 39篇 |
1987年 | 33篇 |
1986年 | 31篇 |
1985年 | 35篇 |
1984年 | 8篇 |
1983年 | 11篇 |
1982年 | 14篇 |
1981年 | 22篇 |
1980年 | 29篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 70篇 |
1976年 | 150篇 |
1975年 | 6篇 |
1974年 | 3篇 |
1972年 | 3篇 |
1969年 | 3篇 |
1967年 | 2篇 |
排序方式: 共有2662条查询结果,搜索用时 281 毫秒
991.
The synthesis of six benzo[e]diazaborine compounds and thier in vitro evaluation against M. tuberculosis H37Rv is described. The compounds 1,2-dihydro-1-hydroxy-2-phenyl-2,4,1-benzo[e]diazaborin-3(4H)-one, 4, and 1,2-dihydro-1-hydroxy-2-(3-pyridyl)-2,4,1-benzo[e]diazaborin-3(4H) - thione, (5), showed the greatest inhibitory activity. 相似文献
992.
AR Spielberg 《Canadian Metallurgical Quarterly》1998,280(15):1353-1359
Increased use of e-mail by physicians, patients, and other health care organizations and staff has the potential to reshape the current boundaries of relationships in medical practice. By comparing reception of e-mail technology in medical practice with its historical analogue, reception of the telephone, this article suggests that new expectations, practice standards, and potential liabilities emerge with the introduction of this new communication technology. Physicians using e-mail should be aware of these considerations and construct their e-mail communications accordingly, recognizing that e-mail may be included in the patient's medical record. Likewise, physicians should discuss the ramifications of communicating electronically with patients and obtain documented informed consent before using e-mail. Physicians must keep patient information confidential, which will require taking precautions (including encryption to prevent interception) to preserve patient information, trust, and the integrity of the patient-physician relationship. 相似文献
993.
AR Davis PL Mascolo PL Bunger KM Sipes MT Quinn 《Canadian Metallurgical Quarterly》1998,64(1):114-123
Neutrophils play an essential role in the cellular defense of the bovine mammary gland and compromised leukocyte function has been linked to the development of bovine mastitis. During mastitis, large numbers of leukocytes migrate into the mammary tissues where they become activated, resulting in the assembly of neutrophil membrane and cytosolic proteins to form a superoxide anion-generating complex known as the NADPH oxidase. The key membrane-associated component of the NADPH oxidase is flavocytochrome b, which is a heterodimer of p22-phox and gp91-phox. Currently, only the human, porcine, murine, and rattus p22-phox and the human, porcine, and murine gp91-phox gene sequences are known. Because of the important role neutrophils play in bovine host defense, we carried out studies to clone, sequence, and analyze expression of bovine flavocytochrome b. Using polymerase chain reaction cloning techniques and a bovine spleen cDNA library we have cloned both of the bovine flavocytochrome b subunits, p22-phox and gp91-phox. Comparison of the bovine sequences with those of other species also revealed important information regarding key structural features of gp91-phox and p22-phox, including location of putative glycosylation sites. This study greatly contributes to our understanding of the potential functional sites of the flavocytochrome b subunits as well as providing information that can be used to study the role of neutrophils in bovine inflammatory diseases such as mastitis. 相似文献
994.
J Grünenfelder U Bartram R Van Praagh KE Bove WW Bailey RA Meyer PR Koenig AR Perez DC Schwartz 《Canadian Metallurgical Quarterly》1998,65(6):1790-1791
A rare window type of patent ductus arteriosus is reported that was large (15 mm in maximal transverse dimension) but had virtually no length and hence was externally invisible. The smaller aortic isthmus (4 mm in diameter), which was intrapericardial, was mistaken for the ductus and was inadvertently clip-occluded, leading to death. After a specific diagnosis is made, the large window ductus should be patched on cardiopulmonary bypass with a transpulmonary approach. 相似文献
995.
D Moher B Pham A Jones DJ Cook AR Jadad M Moher P Tugwell TP Klassen 《Canadian Metallurgical Quarterly》1998,352(9128):609-613
BACKGROUND: Few meta-analyses of randomised trials assess the quality of the studies included. Yet there is increasing evidence that trial quality can affect estimates of intervention efficacy. We investigated whether different methods of quality assessment provide different estimates of intervention efficacy evaluated in randomised controlled trials (RCTs). METHODS: We randomly selected 11 meta-analyses that involved 127 RCTs on the efficacy of interventions used for circulatory and digestive diseases, mental health, and pregnancy and childbirth. We replicated all the meta-analyses using published data from the primary studies. The quality of reporting of all 127 clinical trials was assessed by means of component and scale approaches. To explore the effects of quality on the quantitative results, we examined the effects of different methods of incorporating quality scores (sensitivity analysis and quality weights) on the results of the meta-analyses. FINDINGS: The quality of trials was low. Masked assessments provided significantly higher scores than unmasked assessments (mean 2.74 [SD 1.10] vs 2.55 [1.20]). Low-quality trials (score < or = 2), compared with high-quality trials (score > 2), were associated with an increased estimate of benefit of 34% (ratio of odds ratios [ROR] 0.66 [95% CI 0.52-0.83]). Trials that used inadequate allocation concealment, compared with those that used adequate methods, were also associated with an increased estimate of benefit (37%; ROR=0.63 [0.45-0.88]). The average treatment benefit was 39% (odds ratio [OR] 0.61 [0.57-0.65]) for all trials, 52% (OR 0.48 [0.43-0.54]) for low-quality trials, and 29% (OR 0.71 [0.65-0.77]) for high-quality trials. Use of all the trial scores as quality weights reduced the effects to 35% (OR 0.65 [0.59-0.71]) and resulted in the least statistical heterogeneity. INTERPRETATION: Studies of low methodological quality in which the estimate of quality is incorporated into the meta-analyses can alter the interpretation of the benefit of intervention, whether a scale or component approach is used in the assessment of trial quality. 相似文献
996.
997.
A Ghavamzadeh P Nasseri MR Eshraghian M Jahani I Baybordi J Nateghi A Khodabandeh AR Sadjadi M Mohyeddin Y Khademi 《Canadian Metallurgical Quarterly》1998,22(12):1167-1169
This study concerns the effects of several pre-transplant features on outcome for patients with beta thalassemia major who underwent bone marrow transplantation (BMT). Seventy patients with beta thalassemia major underwent bone marrow transplantation during the period 1991-1997 in Shariati Hospital in Tehran, Iran. The survival and rejection curves levelled off at 8 and 18 months after transplantation at 82.6% and 11.4%, respectively. Pre-transplant clinical features (age, serum ferritin, portal fibrosis, hepatomegaly and quality of chelation therapy) were examined for their effects on survival and recurrence of thalassemia in this group of patients who were less than 16 years old. Increasing age, presence of portal fibrosis and increasing serum ferritin were significantly associated with reduced probability of survival (P = 0.0047, P = 0.016 and P = 0.024, respectively). Hepatomegaly and inadequate pre-transplant chelation therapy which were documented as poor prognostic factors in previous studies, were not evaluable in this study. We also showed the benefits of transplanting more than 5.5 x 10(8)/kg cells in this group of patients with no increase in complications. 相似文献
998.
999.
A 16-year-old male developed numerous pyogenic granuloma like-lesions across his neck, chest and back after 6 weeks isotretinoin therapy for cystic acne. The isotretinoin was ceased and he was commenced on oral steroids. After 6 weeks, the lesions were almost completely healed. However, due to worsening comedonal acne, the patient was commenced on topical tretinoin cream 0.05% twice daily to his chest. He was reviewed 2 weeks later and, surprisingly, 2 new pyogenic granuloma-like lesions had developed on his chest. These lesions persisted until the topical tretinoin was ceased 3 months later. 相似文献
1000.