全文获取类型
收费全文 | 1925篇 |
免费 | 8篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 64篇 |
金属工艺 | 5篇 |
机械仪表 | 8篇 |
建筑科学 | 7篇 |
能源动力 | 8篇 |
轻工业 | 19篇 |
水利工程 | 1篇 |
无线电 | 36篇 |
一般工业技术 | 66篇 |
冶金工业 | 1668篇 |
原子能技术 | 3篇 |
自动化技术 | 38篇 |
出版年
2023年 | 5篇 |
2022年 | 4篇 |
2021年 | 9篇 |
2019年 | 4篇 |
2018年 | 5篇 |
2016年 | 3篇 |
2015年 | 5篇 |
2014年 | 6篇 |
2013年 | 9篇 |
2012年 | 14篇 |
2011年 | 15篇 |
2010年 | 8篇 |
2009年 | 11篇 |
2008年 | 11篇 |
2007年 | 14篇 |
2006年 | 9篇 |
2005年 | 10篇 |
2004年 | 4篇 |
2003年 | 9篇 |
2001年 | 5篇 |
2000年 | 7篇 |
1999年 | 48篇 |
1998年 | 523篇 |
1997年 | 307篇 |
1996年 | 195篇 |
1995年 | 111篇 |
1994年 | 78篇 |
1993年 | 117篇 |
1992年 | 12篇 |
1991年 | 17篇 |
1990年 | 15篇 |
1989年 | 22篇 |
1988年 | 27篇 |
1987年 | 24篇 |
1986年 | 30篇 |
1985年 | 22篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 10篇 |
1981年 | 11篇 |
1980年 | 16篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 39篇 |
1976年 | 89篇 |
1975年 | 4篇 |
1970年 | 4篇 |
1930年 | 4篇 |
1909年 | 3篇 |
1903年 | 2篇 |
排序方式: 共有1933条查询结果,搜索用时 46 毫秒
31.
32.
N Schaap A Schattenberg B B?r F Preijers A Geurts van Kessel R van der Maazen T de Boo T de Witte 《Canadian Metallurgical Quarterly》1997,98(3):750-759
One hundred and eighty-one consecutive patients with standard-risk leukaemia were transplanted with HLA-identical sibling grafts depleted of lymphocytes using counter-flow centrifugation. In 116 patients, standard conditioning was intensified by the addition of anthracyclines. Multivariate analysis revealed significantly more acute GVHD > or = grade 2 and a trend towards more chronic GVHD in patients conditioned with the addition of anthracyclines. For all patients the risk for chronic GVHD, but not for acute GVHD increased with a higher number of T cells in the graft. The projected 5-year probability of relapse was significantly lower in the group of patients conditioned with anthracyclines; 26% versus 52% (P = 0.015). In multivariate analysis the addition of anthracyclines to the conditioning regimen was the only significant factor contributing to a lower probability of relapse. The projected 5-year probability of leukaemia-free survival [LFS] in the patients conditioned with and without the addition of anthracyclines was 56% and 36%, respectively (P = 0.004). In multivariate analysis the addition of anthracyclines to the conditioning regimen correlated significantly with a lower number of mixed chimaeras in patients at 6 and 12 months after BMT. Mixed chimaerism at 6 months after transplantation did not significantly correlate with a higher incidence of relapse in further follow-up. In contrast, mixed chimaerism at 12 months after BMT was significantly associated with higher relapse rate. We conclude that the addition of anthracyclines to the conditioning regimen improves outcome of BMT using T-cell-depleted grafts. 相似文献
33.
Chondromas are benign tumours of cartilage which are rare in the head and neck. We present a case report of a chondroma in the neck of condyle and demonstrate the value of multiplanar spiral CT and the limitations of 3D reconstruction. 相似文献
34.
SH Lisanby DP Devanand MS Nobler J Prudic L Mullen HA Sackeim 《Canadian Metallurgical Quarterly》1996,12(3):156-164
Numerous studies have confirmed the distinct biological behavior of two subsets of prostate cancer diagnosed incidentally after either transurethral resection (TURP) or open prostatectomy for presumed benign prostatic hyperplasia (BPH). Focal, low-grade lesions are associated with a low risk for clinical progression and are designated as stage T1a or A1. These cases have traditionally been managed conservatively with close clinical observation. In contrast, multifocal, high-volume, or high-grade tumors are associated with a more aggressive clinical course and are designated as stage T1b or A2. Early definitive intervention is usually advocated for these latter patients. Therefore, accurate pathological assignment to either stage T1a or T1b is crucial for selection of appropriate management options. A variety of methods for staging patients with incidentally detected prostate cancer have been proposed, including detailed histological analysis, repeat TURP or transurethral biopsy, serial prostate-specific antigen (PSA) analysis, and imaging with either transrectal ultrasound (TRUS) or magnetic resonance (MRI) techniques. This article critically examines the clinical utility of these staging modalities for patients with incidentally detected prostate cancer. 相似文献
35.
Ohne Zusammenfassung 相似文献
36.
37.
AE Barker-Griffith BW Streeten JL Abraham DP Schaefer SW Norton 《Canadian Metallurgical Quarterly》1998,105(3):535-538
PURPOSE: This study aimed to identify a dangerous new weapon capable of causing damage to the ocular and periocular regions. METHODS: The authors report two patients who had penetrating ocular injury in the past year because of homemade recreational potato guns. RESULTS: In one 14-year-old boy, projectiles from the firing of a potato gun resulted in orbital and cranial injuries that were life threatening with widespread fractures, marked disruption of facial structures, a cerebrospinal fluid fistula requiring bifrontal surgical repair, and loss of one eye. In a separate accident with a different potato gun, a 14-year-old boy who was wearing glasses at the time of injury had a sight-threatening perforating corneal laceration. CONCLUSION: Practitioners must be aware of the existence of these new, homemade unregulated devices. Information about the use and construction of these guns is widespread on the Internet, but no injuries resulting from these guns currently are documented in the medical literature. 相似文献
38.
Because knowledge has advanced in several fields related to the treatment of early breast cancer, revising the landmark 1992 standards for breast-conservation treatment by these four organizations is appropriate. The current report reviews and summarizes the literature and describes the selection and evaluation of patients, the technical aspects of surgical treatment and irradiation, follow-up care, and areas for further research. 相似文献
39.
40.
M Visser DP Kiel J Langlois MT Hannan DT Felson PW Wilson TB Harris 《Canadian Metallurgical Quarterly》1998,49(5-6):745-747
Aim of the study was investigate the cross-sectional relationship between body composition and bone mineral density (BMD) in very old men and women. The study sample consisted of 504 women and 285 men, aged 72-93 yr, participating in examination 22 (1992-1993) of the Framingham Heart Study. Total body BMD, regional BMD, and soft-tissue body composition was measured by dual-energy X-ray absorptiometry. Both muscle mass and percentage body fat were positively associated with total body BMD in women. After adjustment for age, physical activity, smoking status, estrogen use, and thiazide use, BMD increased with increasing tertile of muscle mass (p = 0.007) and with increasing tertile of percentage body fat (p = 0.0001) in women. In men muscle mass, not percentage body fat, was positively associated with BMD. After adjustment for potential confounders, BMD remained associated with muscle mass only (p = 0.02). These results were similar for leg BMD and arm BMD. The study suggests that the influence of muscle and fat mass on bone mineral density is different between very old men and women. 相似文献