全文获取类型
收费全文 | 104668篇 |
免费 | 8968篇 |
国内免费 | 5006篇 |
专业分类
电工技术 | 5830篇 |
技术理论 | 9篇 |
综合类 | 7427篇 |
化学工业 | 17633篇 |
金属工艺 | 5566篇 |
机械仪表 | 6494篇 |
建筑科学 | 7804篇 |
矿业工程 | 3135篇 |
能源动力 | 2937篇 |
轻工业 | 7875篇 |
水利工程 | 2100篇 |
石油天然气 | 6696篇 |
武器工业 | 914篇 |
无线电 | 11895篇 |
一般工业技术 | 12240篇 |
冶金工业 | 4681篇 |
原子能技术 | 1203篇 |
自动化技术 | 14203篇 |
出版年
2024年 | 460篇 |
2023年 | 1709篇 |
2022年 | 3036篇 |
2021年 | 4174篇 |
2020年 | 3275篇 |
2019年 | 2714篇 |
2018年 | 3063篇 |
2017年 | 3447篇 |
2016年 | 3120篇 |
2015年 | 4173篇 |
2014年 | 5199篇 |
2013年 | 6477篇 |
2012年 | 6905篇 |
2011年 | 7446篇 |
2010年 | 6664篇 |
2009年 | 6417篇 |
2008年 | 6431篇 |
2007年 | 6034篇 |
2006年 | 5908篇 |
2005年 | 5021篇 |
2004年 | 3486篇 |
2003年 | 3106篇 |
2002年 | 3004篇 |
2001年 | 2625篇 |
2000年 | 2347篇 |
1999年 | 2384篇 |
1998年 | 1836篇 |
1997年 | 1559篇 |
1996年 | 1399篇 |
1995年 | 1208篇 |
1994年 | 973篇 |
1993年 | 728篇 |
1992年 | 585篇 |
1991年 | 422篇 |
1990年 | 313篇 |
1989年 | 262篇 |
1988年 | 214篇 |
1987年 | 133篇 |
1986年 | 99篇 |
1985年 | 63篇 |
1984年 | 50篇 |
1983年 | 48篇 |
1982年 | 38篇 |
1981年 | 21篇 |
1980年 | 21篇 |
1979年 | 11篇 |
1977年 | 3篇 |
1973年 | 3篇 |
1959年 | 9篇 |
1951年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
本文着重介绍了构成《现代勘探决策理论系统》的5个主要计算机模块,即:生油岩热演化处理、求任意曲边形面积、数学模拟预测资源量、勘探经济评价分析及决策、辅助处理等模块。该系统曾在塔里木盆地和准噶尔盆地的油气资源评价和勘探决策中发挥了作用,受到了专家和用户的好评。 相似文献
32.
33.
Mei Xuan Xu Wen Guang Liu Yun Lin Guan Zuo Peng Bi Kang De Yao 《Polymer International》1995,38(2):205-209
The phase behavior of a hybrid polymer network (HPN) composed of poly[(propylene glycol maleate)-co-(propylene glycol phthalate)] crosslinked with styrene and polyester–urethane crosslinked with methylene-bis-ortho-chloroaniline was examined. The correlation between phase separation and impact strength of the HPNs is discussed. The composition of HPNs has an effect on their properties. 相似文献
34.
This study employs a relational dialectics approach to gain insights into the nature of relational communication via Cyworld , a Korean social network site. Qualitative analysis of in-depth interview data from 49 users suggests that Cyworld users routinely negotiate multiple dialectical tensions that are created within the online world, transferred from face-to-face contexts, or imposed by interpersonal principles that relate to Korea's collectivistic culture. The interviewees experienced a new relational dialectic of interpersonal relations versus self-relation, analogous to Baxter and Montgomery's (1996) connection-autonomy contradiction. Their responses suggest that Cyworld's design features and functions encourage users to transcend the high-context communication of Korean culture by offering an alternative channel for elaborate and emotional communication, which fosters the reframing of relational issues offline. Cy-Ilchons (online buddies) virtually extend the Korean cultural concept of blood ties, called yons, in ways that intensify the openness-closedness contradiction at early stages of relationship formation. 相似文献
35.
压力容器材料质量控制的几个重要环节 总被引:2,自引:0,他引:2
针对压力容器材料方面存在的问题,从设计、采购、检验、制造等环节进行了分析,根据实际情况确定材料的质量控制要点。材料使用前要通过各种检测手段,判断材料的真实性,确保所用材料合格;并应从设计、选材、采购、计划、填报内容和选择可靠的供应方等方面加以控制,确保材料的正确使用,为压力容器产品的材料控制提供借鉴。 相似文献
36.
高瑞霞 《消防技术与产品信息》2005,(3):59-60
设想某一个城镇生产木材调色板的流水线车间里 ,由于电器原因引发了一场火灾 ,致使建筑物坍塌。没有人能够确切地说出有多少工人被埋压在里面 ,更糟的是 ,当毗邻墙体坍塌时 ,隔壁的旧轮胎储藏室也被埋压在下面。于是市消防局派遣一批机器人去现场救援。第一个到达的机器人进入现场调查情况 ,该机器人能忍耐80 0℃的高温炙烤 ,身上安装了摄像机 ,可以给 90 m外的控制室发送图片 ,控制室的指挥人员就可以根据图片决定是否派消防队员冒险进入现场。第二个机器人是无人驾驶卡车 ,进入后便从 75 m远的地方以2 6 gal/ s的速度往火场喷水 ,并用它所… 相似文献
37.
利用平板型热管纺丝装置对普通高速纺丝机进行技术改造,并一步法生产出充分结晶的PET纤维(FCY)。该纤维可直接用于织造,调节热管温度、热管安装位置可获得满足后道工序不同需要的FCY。 相似文献
38.
39.
The cardioprotective effects of EGb 761 on the release of nitric oxide (NO), the concentration of serum thiobarbituric acid reaction substance (TBARS), the activity of creatine kinase (CK) and the incidence of ventricular arrhythmias were investigated in myocardial ischemia-reperfusion injury in vivo. Using sodium nitrite (NaNO2) as standard source of nitric oxide (NO), we compared the correlation coefficients of the three measuring methods used currently in the determination of NOFe2+(DETC)2 complex with that of the measuring method suggested in this study. The result showed that measuring the whole height of three splitting signals is the best linear correlation to the concentration of NO comparing with other methods in this system. Using this method, we observed the effects of EGb 761 on NOFe2+(DETC)2 complex in myocardial ischemia-reperfusion injury in vivo. The hearts of the Wistar rats were subjected to 30 min of ischemia and 10 min of reperfusion in vivo. Different doses of EGb 761 (25, 50, 100, 200 mg/kg i.p.), superoxide dismutase (SOD, 10(4) U/kg), l-arginine (50 mg/kg i.p.) and nitric oxide synthase (NOS) inhibitor NG-nitro-l-arginine (NNA, 50 mg/kg i.p.) were administered to the ischemia-reperfusion rats. EGb 761 under the dose of 100 mg/kg increased the signal intensity of NOFe2+(DETC)2 complex, while EGb 761 at 200 mg/kg showed an effect of decreasing the signal intensity of NOFe2+(DETC)2 complex. EGb 761 inhibited the formation of TBARS, the release of CK, and mitigated the incidence of ventricular arrhythmias in a dose dependent way. Both l-arginine and SOD increased the signal intensity of NOFe2+(DETC)2 complex and inhibited the formation of TBARS, the leakage of CK and the incidence of ventricular arrhythmia. NNA not only had no protective effects on myocardial injury, but also increased the incidence of reperfusion-induced arrhythmia. In conclusion, EGb 761 has cardiovascular protective effects by means of adjusting the level of NO and inhibiting oxygen free radicals induced lipid peroxidation in myocardial ischemia-reperfusion injury in vivo. 相似文献
40.
K Yun 《Canadian Metallurgical Quarterly》1998,13(2):425-435
The solution structure of a synthetic ET(B) selective agonist, ET-1[Cys(Acm)(1,15), Ala3, Leu7, dAsp8, Aib11] has been solved by 1H NMR and molecular modelling studies. Such solution structures of linear modified peptides in aqueous methanol are being used in an ongoing program of research designed to assist in an understanding of the basic structural requirements for the biological activity of vasoconstrictors. The resulting structure of this peptide is characterised by an alpha-helical conformation between residues Leu6-His16 and by N- and C-termini which assume no defined conformation. A knowledge of the solution structures of this and related peptides, which are ET(B) selective agonists, are proving to be important in the understanding of how they interact with the ET(B) receptor. 相似文献