全文获取类型
收费全文 | 145450篇 |
免费 | 11618篇 |
国内免费 | 6099篇 |
专业分类
电工技术 | 8081篇 |
技术理论 | 14篇 |
综合类 | 9128篇 |
化学工业 | 24534篇 |
金属工艺 | 8643篇 |
机械仪表 | 9980篇 |
建筑科学 | 11578篇 |
矿业工程 | 5020篇 |
能源动力 | 4233篇 |
轻工业 | 8803篇 |
水利工程 | 2387篇 |
石油天然气 | 10926篇 |
武器工业 | 1212篇 |
无线电 | 15597篇 |
一般工业技术 | 16899篇 |
冶金工业 | 7252篇 |
原子能技术 | 1467篇 |
自动化技术 | 17413篇 |
出版年
2024年 | 666篇 |
2023年 | 2565篇 |
2022年 | 4454篇 |
2021年 | 6048篇 |
2020年 | 4716篇 |
2019年 | 3885篇 |
2018年 | 4261篇 |
2017年 | 4774篇 |
2016年 | 4373篇 |
2015年 | 5882篇 |
2014年 | 7116篇 |
2013年 | 8490篇 |
2012年 | 9056篇 |
2011年 | 9801篇 |
2010年 | 8359篇 |
2009年 | 8021篇 |
2008年 | 7961篇 |
2007年 | 7445篇 |
2006年 | 7870篇 |
2005年 | 6874篇 |
2004年 | 4359篇 |
2003年 | 4123篇 |
2002年 | 3838篇 |
2001年 | 3478篇 |
2000年 | 3487篇 |
1999年 | 3984篇 |
1998年 | 3157篇 |
1997年 | 2637篇 |
1996年 | 2514篇 |
1995年 | 2148篇 |
1994年 | 1753篇 |
1993年 | 1188篇 |
1992年 | 988篇 |
1991年 | 689篇 |
1990年 | 560篇 |
1989年 | 448篇 |
1988年 | 362篇 |
1987年 | 233篇 |
1986年 | 180篇 |
1985年 | 104篇 |
1984年 | 81篇 |
1983年 | 75篇 |
1982年 | 62篇 |
1981年 | 42篇 |
1980年 | 34篇 |
1979年 | 20篇 |
1978年 | 2篇 |
1965年 | 1篇 |
1959年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
WC对Cu/WC_P复合材料性能及组织的影响 总被引:8,自引:0,他引:8
通过WC含量对WC/Cu复合材料性能的影响,确定了冷压-烧结法制备Cu/WC材料的适宜WC含量为10vol%左右。并就WC对该材料组织和再结晶行为的影响进行了有益的探讨。 相似文献
73.
从油田现场反应的情况出发,对调整井固井,尾管固井,大位移井套管固井和其他固井的质量问题进行了分析,针对各种问题产生的原因,提出了相应换解决办法。 相似文献
74.
SM Kornblau E Estey T Madden HT Tran S Zhao U Consoli V Snell G Sanchez-Williams H Kantarjian M Keating RA Newman M Andreeff 《Canadian Metallurgical Quarterly》1997,15(5):1796-1802
PURPOSE: Expression of the multidrug resistance gene (MDR1) p170 protein is frequent in leukemic blasts from patients with relapsed acute myelogenous leukemia (AML). A phase I study using the nonimmunosuppressive MDR1 blocker SDZ PSC-833 (PSC) in combination with mitoxantrone (MITO) and etoposide (VP) was performed. PATIENTS AND METHODS: Starting doses (LVL0) of MITO (3.25 mg/m2/d on days 1 and 3 to 6) and VP (210 mg/m2/d on days 1 and 3 to 5) were 40% of the maximal-tolerated dose (MTD) from a prior study. A 1.5-mg/kg loading dose of PSC was followed by a 120-hour continuous infusion of 10 mg/kg/d on days 2 to 6. Blood samples for PSC, MITO, and VP pharmacokinetics (PK) were taken on days 1 and 3, and samples for MDR1 expression were taken on day 0. RESULTS: Severe mucositis developed in all patients at LVL0; therefore, MITO and VP doses were reduced to 2.5 and 170 mg/m2 (LVL-1) for the next seven patients, and this dose proved to be MTD. All LVL0 and three LVL-1 patients had transient elevations in the serum bilirubin level to > or = 4 mg/dL. Serum creatinine level increased to greater than 2 mg/dL in one case. There were no other grade 3 or 4 nonhematologic toxicities observed. The peripheral blood was cleared of leukemia in three LVL0 and four LVL-1 patients. The marrow was cleared of leukemic cells in one LVL0 and five LVL-1 patients, and a significant reduction in marrow leukemic infiltrate was observed in eight of 10. No patient achieved complete remission (CR), and all died of progressive disease (n = 8) or infection (n = 2). MDR1 expression was detected by fluorescent-activated cell sorter (FACS) analysis in five of seven cases. An elevated MDR1 mRNA level was detected by quantitative polymerase chain reaction (Q-PCR) in six of eight cases studied. Clearing of leukemia cells from the marrow occurred in four of six MDR1-positive and one of three MDR1-negative patients. Despite the fact that LVL0 doses had to be reduced due to toxicity, coadministration of PSC did not produce a consistent effect on MITO PK; however, it did repeatedly lead to increased levels of VP in the serum. CONCLUSION: We conclude that PSC-MITO-VP is a tolerable regimen with antileukemic activity. Addition of PSC necessitated a 66% reduction in MITO and VP doses from a prior study without PSC. 相似文献
75.
76.
Polymorphonuclear leucocyte (PMNL) accumulation in extravascular tissues and inflammatory exudates is dependent on their migration through blood vessel endothelium and then through connective tissue. Previously we utilized a barrier of human synovial and dermal fibroblasts (HSF or HDF) grown on microporous filters, as a model of PMNL migration through connective tissue. Those studies showed that beta 2 (CD18) and the beta 1 integrins, very late activation antigen-5 (VLA-5) and VLA-6, in part mediate this PMNL migration. Here we report that VLA-4, which can also be expressed at low levels on activated PMNL, is also involved in PMNL migration induced by C5a through fibroblast (HSF and HDF) barriers, because monoclonal antibody (mAb) to VLA-4 significantly inhibited (by 20-30%) PMNL migration. Blocking the function of CD18, VLA-5 or VLA-6 was not required for detection of the VLA-4-mediated migration. Combination treatment with mAb to VLA-4 and with mAb to VLA-5 or to VLA-6 further inhibited PMNL migration, irrespective of whether CD11/CD18 mechanisms were blocked with anti-CD18 mAb or not. Treatment of PMNL with a peptide based on the VLA-4-binding domain in the CS-1 fragment of fibronectin, but not a control peptide, inhibited PMNL migration to a comparable extent to treatment with mAb to VLA-4. A low level of VLA-4 was expressed on C5a-activated PMNL, detected by immunofluorescence flow cytometry. These results suggest that VLA-4 can be mobilized by human peripheral blood PMNL and can, in addition to VLA-5, VLA-6 and CD11/CD18 integrins, mediate PMNL migration through connective tissue. This is in marked contrast to PMNL transendothelial migration, where beta 1 integrins appear to play no significant role. 相似文献
77.
Restless legs syndrome affects millions, but most healthcare providers don't know it exists. Its sleep-deprived victims are plagued by indescribable crawling sensations in their legs that occur at night and that are only relieved by moving the legs. Many home healthcare clients, already challenged by their primary illness, are also affected by the persistent symptoms of Restless Legs Syndrome. It is important that home care nurses learn about Restless Legs Syndrome-what it is, how to assess it, and what can be done about it. 相似文献
78.
广义杠杆规则及其在配方计算中的应用 总被引:5,自引:3,他引:2
作者将相图中的一维杠杆规则推广至多元配料系统而成为广义杠杆规则,并利用这一规则对配方计算中解的可行域问题进行了深入的讨论,给出了几何解释及工艺诠释,对配方设计有一定的指导作用。 相似文献
79.
熔窑玻璃液流数值模拟的新发展 总被引:1,自引:0,他引:1
熔窑玻璃液流数值模拟的新发展赵国昌(清华大学核能技术设计研究院,100084)NewDevelopmentoftheNumericalSimulationforFlowandHeatTransferofGlassMeltinTankFurnace¥Z... 相似文献
80.
本文基于静态相关性分析和动态调整相结合的方法,提出了一种逻辑程序的执行模型,它不仅开发了“与“并行,同进也开发了一定的“或“并行,从而有效地加速了逻辑程序的执行。 相似文献