全文获取类型
收费全文 | 416908篇 |
免费 | 6079篇 |
国内免费 | 2152篇 |
专业分类
电工技术 | 8443篇 |
技术理论 | 1篇 |
综合类 | 1451篇 |
化学工业 | 62092篇 |
金属工艺 | 17059篇 |
机械仪表 | 14302篇 |
建筑科学 | 9396篇 |
矿业工程 | 2429篇 |
能源动力 | 11842篇 |
轻工业 | 29885篇 |
水利工程 | 4554篇 |
石油天然气 | 8694篇 |
武器工业 | 127篇 |
无线电 | 50586篇 |
一般工业技术 | 84354篇 |
冶金工业 | 75474篇 |
原子能技术 | 9388篇 |
自动化技术 | 35062篇 |
出版年
2022年 | 3060篇 |
2021年 | 4574篇 |
2020年 | 3442篇 |
2019年 | 4169篇 |
2018年 | 6903篇 |
2017年 | 6971篇 |
2016年 | 7362篇 |
2015年 | 4952篇 |
2014年 | 7868篇 |
2013年 | 20924篇 |
2012年 | 12390篇 |
2011年 | 16220篇 |
2010年 | 12994篇 |
2009年 | 14521篇 |
2008年 | 14830篇 |
2007年 | 14506篇 |
2006年 | 13077篇 |
2005年 | 11718篇 |
2004年 | 10897篇 |
2003年 | 10806篇 |
2002年 | 10241篇 |
2001年 | 10094篇 |
2000年 | 9427篇 |
1999年 | 9781篇 |
1998年 | 24500篇 |
1997年 | 16878篇 |
1996年 | 12943篇 |
1995年 | 9610篇 |
1994年 | 8443篇 |
1993年 | 8429篇 |
1992年 | 6095篇 |
1991年 | 5718篇 |
1990年 | 5709篇 |
1989年 | 5343篇 |
1988年 | 5064篇 |
1987年 | 4432篇 |
1986年 | 4309篇 |
1985年 | 4816篇 |
1984年 | 4424篇 |
1983年 | 3995篇 |
1982年 | 3657篇 |
1981年 | 3733篇 |
1980年 | 3430篇 |
1979年 | 3327篇 |
1978年 | 3337篇 |
1977年 | 3751篇 |
1976年 | 4847篇 |
1975年 | 2850篇 |
1974年 | 2666篇 |
1973年 | 2730篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
The incidence of stress fractures is increasing among competitive and recreational athletes as well as among children and the elderly. By understanding the continuum of bone's response to stress and maintaining an appropriate index of suspicion, the health care provider can diagnose these injuries appropriately. An accurate history and examination is essential and will differentiate stress fractures from other stress reactions. The more common stress fractures are discussed. 相似文献
942.
We report a case of cervical epidural hematoma associated with anticoagulant therapy in a 68 year-old man, who presented with tetraplegia. He was operated 12 hours after the onset. Three months later, he had recovered almost completely. The etiologies and prognosis of such lesions are reviewed. 相似文献
943.
944.
945.
946.
R Levy F Najioullah B Keppi D Thouvenot S Bosshard J Lornage B Lina JF Guerin M Aymard 《Canadian Metallurgical Quarterly》1997,68(5):820-825
This paper presents the results of in vivo measurements on a worker from a fuel reprocessing plant who was involved in an actinide intake. The results revealed that false indications of an actinide lung burden could arise from a contaminant present elsewhere in the chest region. Consequently, it is important that lung monitoring programs for occupational workers handling actinides are conducted with this caution in mind and that due consideration is given even in cases of minor cuts/wounds in order to rule out substantial overestimation of internal radiation doses. 相似文献
947.
Converting cysteine 543 to tyrosine in the influenza virus hemagglutinin (HA) introduces both a basolateral sorting signal and an internalization signal into the HA cytoplasmic domain. Another HA mutant, HA+8, contains eight additional amino acids at the end of the cytoplasmic domain that include a powerful internalization signal. HA+8 was also sorted efficiently to the basolateral surface of Madin-Darby canine kidney cells. The simplest explanation for the observation that multiple sorting phenotypes depend upon the same small amino acid sequence is that certain tyrosine-based internalization signals might also function as basolateral sorting signals. To test this hypothesis, second-site mutations were introduced into HA C543Y or HA+8 to determine if the internalization and basolateral sorting functions can be separated. For HA C543Y, the same sequence positions were important for both basolateral sorting and internalization, but the two functions responded differently to individual amino acid replacements, indicating that they were distinct. For HA+8, the basolateral sorting signal required the same tyrosine as the internalization signal, but did not share any other characteristics. Thus, even when basolateral sorting signals that depend on tyrosine overlap or are co-linear with internalizations signals, the two sorting processes are sensitive to different characteristics of the sequence. 相似文献
948.
OBJECTIVE: To evaluate the therapeutical mechanism of Bushen Shengxue Paste (BSSXP) on anemia. METHODS: Chronic renal failure induced anemia patients were treated with BSSXP, clinical manifestation, anemia and renal function as indicators were observed in patients. The erythropoietin (EPO) and inhibition of colony-forming unit-erythrocyte (CFU-E) in patients' serum were determined by CFU-E in vitro. RESULTS: The patients' symptoms, renal function and anemia were improved after administration with BSSXP 1-2 course. EPO in serum was slightly increased. The inhibition of CFU-E in patient's serum was significantly decreased. CONCLUSIONS: BSSXP could improve the anemia degree, its mechanism might be through clearing the inhibitor of CFU-E in serum. 相似文献
949.
This case report describes an accessory hepatic duct (AHD) identified by intraoperative cholangiography during excisional surgery of a choledochal cyst (CC). The accessory duct was divided and reconstructed successfully to the Roux-en-Y jejunal loop. The postoperative course was uneventful, and follow-up abdominal sonography revealed neither evidence of biliary tract obstruction nor atrophic changes of the liver. It is advocated that an AHD should be meticulously reconstructed if it is divided during excisional surgery of a CC. 相似文献
950.