全文获取类型
收费全文 | 2211篇 |
免费 | 36篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 10篇 |
综合类 | 16篇 |
化学工业 | 24篇 |
金属工艺 | 16篇 |
机械仪表 | 7篇 |
建筑科学 | 5篇 |
矿业工程 | 6篇 |
能源动力 | 1篇 |
轻工业 | 14篇 |
水利工程 | 8篇 |
石油天然气 | 4篇 |
无线电 | 14篇 |
一般工业技术 | 55篇 |
冶金工业 | 2058篇 |
自动化技术 | 17篇 |
出版年
2024年 | 3篇 |
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 2篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 6篇 |
2012年 | 12篇 |
2011年 | 18篇 |
2010年 | 13篇 |
2009年 | 16篇 |
2008年 | 15篇 |
2007年 | 13篇 |
2006年 | 5篇 |
2005年 | 12篇 |
2004年 | 2篇 |
2003年 | 11篇 |
2002年 | 8篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 73篇 |
1998年 | 630篇 |
1997年 | 364篇 |
1996年 | 234篇 |
1995年 | 135篇 |
1994年 | 121篇 |
1993年 | 142篇 |
1992年 | 13篇 |
1991年 | 18篇 |
1990年 | 9篇 |
1989年 | 16篇 |
1988年 | 27篇 |
1987年 | 21篇 |
1986年 | 15篇 |
1985年 | 16篇 |
1982年 | 8篇 |
1981年 | 13篇 |
1980年 | 21篇 |
1978年 | 4篇 |
1977年 | 62篇 |
1976年 | 112篇 |
1975年 | 7篇 |
1973年 | 1篇 |
1966年 | 2篇 |
1955年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有2255条查询结果,搜索用时 234 毫秒
131.
The inclusion of people with developmental disabilities in managed care as part of general efforts by states to enroll and Medicaid recipients in such plans was reviewed. Managed care was defined and the processes by which managed care organizations deliver services were explained. Escalating costs and utilization were discussed as the primary reason for the shift to managed care. The use of Medicaid Section 1115 waivers by states to include Medicaid recipients was explored. The relation between acute health care and long-term care, and the utilization patterns in each, were briefly described. Finally, elements of managed care that are particularly important to people with developmental disabilities, such as care coordination, maintenance of quality, and individual and family support, were discussed. 相似文献
132.
G Manenti L De Gregorio S Pilotti FS Falvella M Incarbone F Ravagnani MA Pierotti TA Dragani 《Canadian Metallurgical Quarterly》1997,18(10):1917-1920
The mapping near Kras2 of pulmonary adenoma susceptibility 1 (Pas1), a major locus affecting inherited predisposition to lung cancer in mice prompted us to test the homologous human region (12p12) for association with lung adenocarcinoma, by a population-based study. We genotyped 213 lung adenocarcinoma patients and 219 healthy blood donor subjects for five polymorphic markers mapping in the putative region of interest. Three marker polymorphisms, located in a region spanning approximately 700 kb, were significantly associated with lung adenocarcinoma risk. Furthermore, polymorphisms in KRAS2 and PTHLH loci were also associated with tumor prognosis. These results suggest the existence of a human Pas1 homologous locus on chromosome 12p12. 相似文献
133.
OBJECTIVE: Because twins are a high-risk group for preterm birth, many clinicians routinely use prophylactic interventions such as home bed rest, hospital bed rest, oral tocolytics, or home uterine activity monitoring to prevent preterm delivery. We sought to identify twin gestations at low risk for spontaneous preterm birth with transvaginal ultrasonography of the cervix to avoid the unnecessary use of prophylactic interventions in these pregnancies. STUDY DESIGN: We measured cervical length at 24 to 26 weeks' gestation by transvaginal ultrasonography in women with twin gestations referred to our prematurity prevention clinic. Each delivery was classified as (1) spontaneous preterm birth < 34 weeks' gestation, (2) delivery at > or = 34 weeks' gestation with intervention, or (3) delivery at > or = 34 weeks' gestation without intervention. Intervention included strict bed rest at home or in the hospital, either parenteral or oral tocolysis, or both, or home uterine activity monitoring. Indicated preterm deliveries and patients with cerclage were excluded from this analysis. The ability of transvaginal cervical length to predict women who would deliver at > or = 34 weeks without intervention was evaluated. A cervical length of 35 mm was chosen by scatter diagram as the best cutoff to discriminate between the group delivered at term without intervention and the other two groups. RESULTS: Of 85 women with twin gestations who underwent ultrasonographic cervical length measurements at 24 to 26 weeks' gestation, 17 had spontaneous preterm birth at < 34 weeks, 23 were delivered at > or = 34 weeks but required intervention, and 45 were delivered at > or = 34 weeks without intervention. The mean cervical length for those delivered at > or = 34 weeks' gestation without intervention (36.4 +/- 5.8 mm) was significantly greater (p < 0.0001) than the mean for those delivered preterm (27.4 +/- 8.5) and those delivered at > or = 34 weeks' gestation who required intervention (27.7 +/- 10.5 mm). The sensitivity, specificity, and positive and negative predictive values of a cervical length > 35 mm for predicting delivery at > or = 34 weeks' gestation are 49%, 94%, 97%, and 31%, respectively. CONCLUSION: A transvaginal ultrasonographic measurement of the cervix of > 35 mm at 24 to 26 weeks in twin gestations can identify patients who are at low risk for delivery before 34 weeks' gestation. 相似文献
134.
TA Serel G Akhan HR Koyuncuo?lu A Oztürk K Do?ruer S Unal K Celik 《Canadian Metallurgical Quarterly》1997,31(6):537-539
The treatment and favorable outcome of a bitch with uterine torsion and two retained fetuses are described. The condition was corrected surgically by ovariohysterectomy. Complications (i.e., septic shock, peritonitis, and hemostatic abnormalities) were managed with aggressive medical therapy. Torsion of the gravid uterus in dogs is a life-threatening condition which can have a successful outcome if medical complications encountered in the pre- and postoperative periods are treated quickly and effectively. 相似文献
135.
136.
137.
通过布洛芬(ibuprofen)的热分解及其动力学研究,运用简单的热分解动力学方法进行计算分析,求出相关的活化能,指前因子和动力学参数。将布洛芬每个温度范围下的热分解过程分为3个阶段分别进行分析计算,发现每个阶段都满足一级反应方程。从而算出布洛芬热分解过程的活化能,指前因子和相关系数。通过对布洛芬热分解过程的研究,及对布洛芬TG和DTG曲线的研究,得出布洛芬在热分解过程中分为3个阶段,分别进行脱水,C-C键断裂和分子键断裂。并且随着升温速率的提高,布洛芬失重速率会逐渐趋向于温度升高的方向发展,即温度升高,布洛芬最大失重速率越大。 相似文献
138.
针对工业测控的现状和需求,提出一种新型测控方案,并对其关键技术进行了研究。系统采用双DSP工作模式,并在此基础上提出了并行FFT算法,实现了双余度数据采集及处理,提高了数据处理效率;采用RS 485无线通信方式实现数据和控制信号收发;上位机端基于LabVIEW开发平台实现了信号收发,并提供ODBC数据库接口,将虚拟仪器技术和面向Internet的Web技术有机结合起来,很好地满足了监测系统互联和资源共享的需求。 相似文献
139.
Generation of tumor immunity by bone marrow-derived dendritic cells correlates with dendritic cell maturation stage 总被引:1,自引:0,他引:1
MS Labeur B Roters B Pers A Mehling TA Luger T Schwarz S Grabbe 《Canadian Metallurgical Quarterly》1999,162(1):168-175
The mutational pattern of IgVH and IgVL genes from synovial tissue B cell hybridomas (n = 8) of patients (n = 4) with rheumatoid arthritis (RA) was analysed, which had been produced by the electrofusion technique without prior in vitro stimulation. The molecular data were correlated with immunohistopathological data and parameters of local disease activity. The IgVH genes of the B cell hybridomas belonged to the VH3 family (DP42; DP47, n = 2; DP53), the VH1 family (DP75), the VH4 family (DP71) and the VH5 family (DP73); 7/7 IgVH genes showed somatic mutations, the R/S ratio (CDR) was > 3 in 4/7 IgVH genes and the mean R/S ratio of all IgVH genes was 9.3 (CDR) and 1.0 (FR), suggesting an antigen-dependent selection. The IgVL/lambda genes belonged to the Vlambda1 family (DPL2, DPL5, DPL8nf), the Vlambda2 family (DPL11, n = 2) and to the Vlambda6 family (IGLV6S1); 6/6 IgVL genes showed somatic mutations, the R/S ratio (CDR) was > 3 in 3/6 IgVL genes and the mean R/S ratio of all IgVL was 3.0 (CDR) and 2.3 (FR), suggesting an antigen-dependent selection. The synovial tissue exhibited germinal centres in the follicles (3/4), with the unique distribution of Ki-M4+ follicular dendritic cells and Ki-67+ proliferating cells and a dominance of IgA+ plasma cells (3/3). All patients were positive for RF in serum and exhibited severe local symptoms (swelling 4/4; warmth 4/4; effusion 2/4), whereas the hybridomas were negative for RF. Since B cell hybridomas showed hypermutation and affinity selection for IgVH and IgVL/lambda genes and the patients exhibited severe local symptoms with germinal centres in synovial tissue, this study indicates that an antigen-driven process is behind the B cell expansion in the synovial tissue of clinically affected joints. These mutated B hybridomas were negative for RF, thus suggesting that antigens different from RF are also involved in the local B cell expansion and in the chronic synovitis of RA. 相似文献
140.
EA Ratovitski MR Alam RA Quick A McMillan C Bao C Kozlovsky TA Hand RC Johnson RE Mains BA Eipper CJ Lowenstein 《Canadian Metallurgical Quarterly》1999,274(2):993-999
Nitric oxide (NO) acts as a neurotransmitter. However, excess NO produced from neuronal NO synthase (nNOS) or inducible NOS (iNOS) during inflammation of the central nervous system can be neurotoxic, disrupting neurotransmitter and hormone production and killing neurons. A screen of a hippocampal cDNA library showed that a unique region of the iNOS protein interacts with Kalirin, previously identified as an interactor with a secretory granule peptide biosynthetic enzyme. Kalirin associates with iNOS in vitro and in vivo and inhibits iNOS activity by preventing the formation of iNOS homodimers. Expression of exogenous Kalirin in pituitary cells dramatically reduces iNOS inhibition of ACTH secretion. Thus Kalirin may play a neuroprotective role during inflammation of the central nervous system by inhibiting iNOS activity. 相似文献