全文获取类型
收费全文 | 6014篇 |
免费 | 6篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 273篇 |
机械仪表 | 10篇 |
建筑科学 | 6篇 |
矿业工程 | 1篇 |
能源动力 | 6篇 |
轻工业 | 499篇 |
石油天然气 | 1篇 |
无线电 | 12篇 |
一般工业技术 | 47篇 |
冶金工业 | 5136篇 |
原子能技术 | 2篇 |
自动化技术 | 21篇 |
出版年
2013年 | 75篇 |
2005年 | 7篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2000年 | 5篇 |
1999年 | 138篇 |
1998年 | 1521篇 |
1997年 | 860篇 |
1996年 | 581篇 |
1995年 | 338篇 |
1994年 | 312篇 |
1993年 | 331篇 |
1992年 | 58篇 |
1991年 | 102篇 |
1990年 | 73篇 |
1989年 | 98篇 |
1988年 | 105篇 |
1987年 | 99篇 |
1986年 | 91篇 |
1985年 | 57篇 |
1984年 | 25篇 |
1983年 | 32篇 |
1982年 | 46篇 |
1981年 | 48篇 |
1980年 | 67篇 |
1979年 | 24篇 |
1978年 | 49篇 |
1977年 | 162篇 |
1976年 | 362篇 |
1975年 | 40篇 |
1974年 | 24篇 |
1973年 | 24篇 |
1972年 | 29篇 |
1971年 | 28篇 |
1970年 | 22篇 |
1969年 | 11篇 |
1968年 | 10篇 |
1967年 | 11篇 |
1966年 | 11篇 |
1965年 | 14篇 |
1964年 | 11篇 |
1963年 | 8篇 |
1962年 | 4篇 |
1961年 | 4篇 |
1959年 | 6篇 |
1958年 | 8篇 |
1957年 | 5篇 |
1956年 | 10篇 |
1955年 | 7篇 |
1947年 | 4篇 |
排序方式: 共有6020条查询结果,搜索用时 14 毫秒
51.
52.
53.
54.
55.
JR Hoff 《Canadian Metallurgical Quarterly》1998,5(2):46-47
Neuroimaging techniques have a great impact on the evaluation and treatment of patients with epilepsy. Positron emission tomographic studies with 18F-FDG can provide valuable data for presurgical localization of epileptogenic zones. There are also a number of receptor ligands for PET studies available, including benzodiazepine, opiate and cholinergic tracers. Ligands for monoamine oxidase B and glutamate receptors are being developed. 相似文献
56.
Understanding the mechanisms responsible for photodamage to the skin is most important for dermatology. 3-D cultures have been used as tools to mimic the in vivo situation for several years. We irradiated such a system containing human dermal fibroblasts cultured in collagen gels, a well-known model considered to be a dermal equivalent, which reproduces the interaction between cells and the surrounding extracellular matrix. The effects of solar irradiation (315-800 nm) on the steady-state levels of the mRNAs of extracellular matrix components (type I and III collagens) and their degrading enzymes (interstitial collagenase, MMP-1 and stromelysin 1, MMP-3) were measured. Exposure to low levels of solar radiation (0-10 J cm-2 in the UVA, i.e. suberythemal UVA doses) caused a transient decrease in type I procollagen mRNA, an increase in MMP-mRNA, and no change in type III procollagen mRNA steady-state levels. These results describe the early changes in the connective tissue of the skin following exposure to low-level solar stimulation, and may help explain the long-term changes in photodamaged skin. 相似文献
57.
A Bhandari DG Jones JR Schullek K Vo CA Schunk LL Tamanaha D Chen Z Yuan MC Needels MA Gallop 《Canadian Metallurgical Quarterly》1998,8(17):2303-2308
Phosphomannose Isomerase (PMI) has been shown by genetic methods to be an essential enzyme in fungal cell wall biosynthesis. The PMI inhibitor AF14049 was discovered as an unanticipated side product from high-throughput library screening against the enzyme from C, albicans. Solid-phase synthetic methods were developed and a series of libraries and discrete analogs synthesized to explore SAR around AF14049. 相似文献
58.
DK Ball GA Surveyor JR Diehl CL Steffen M Uzumcu MA Mirando DR Brigstock 《Canadian Metallurgical Quarterly》1998,59(4):828-835
59.
60.
Dermatofibrosarcoma protuberans (DFSP) is a low-intermediate-grade cutaneous sarcoma that has a marked propensity for local recurrence after excision. The Bednar variant of this tumor is even less common and is distinguished histologically by the dispersal of melanin containing cells in an otherwise typical DFSP. Both are considered to be tumors of the third and forth decades of life, but both DFSP and the Bednar variant have been described in children. Until this report of a congenital Bednar tumor, only the DFSP has also been described in the neonate. The histopathology and surgical management of DFSP and Bednar tumors are outlined with emphasis on reported experience in the pediatric population. The surgical management of these lesions in children is based on numerous series in adults and the limited pediatric experience. The recommended treatment is wide excision with 3-cm margins of visibly uninvolved tissue and inclusion of superficial fascia. 相似文献