全文获取类型
收费全文 | 32562篇 |
免费 | 1501篇 |
国内免费 | 111篇 |
专业分类
电工技术 | 428篇 |
综合类 | 232篇 |
化学工业 | 6127篇 |
金属工艺 | 693篇 |
机械仪表 | 682篇 |
建筑科学 | 1123篇 |
矿业工程 | 114篇 |
能源动力 | 1116篇 |
轻工业 | 4561篇 |
水利工程 | 264篇 |
石油天然气 | 161篇 |
武器工业 | 6篇 |
无线电 | 2456篇 |
一般工业技术 | 4833篇 |
冶金工业 | 6445篇 |
原子能技术 | 259篇 |
自动化技术 | 4674篇 |
出版年
2024年 | 54篇 |
2023年 | 184篇 |
2022年 | 661篇 |
2021年 | 957篇 |
2020年 | 644篇 |
2019年 | 738篇 |
2018年 | 873篇 |
2017年 | 933篇 |
2016年 | 893篇 |
2015年 | 701篇 |
2014年 | 1033篇 |
2013年 | 1732篇 |
2012年 | 1555篇 |
2011年 | 1936篇 |
2010年 | 1429篇 |
2009年 | 1446篇 |
2008年 | 1336篇 |
2007年 | 1163篇 |
2006年 | 932篇 |
2005年 | 970篇 |
2004年 | 1000篇 |
2003年 | 903篇 |
2002年 | 879篇 |
2001年 | 738篇 |
2000年 | 578篇 |
1999年 | 560篇 |
1998年 | 2081篇 |
1997年 | 1362篇 |
1996年 | 955篇 |
1995年 | 646篇 |
1994年 | 499篇 |
1993年 | 551篇 |
1992年 | 230篇 |
1991年 | 298篇 |
1990年 | 240篇 |
1989年 | 203篇 |
1988年 | 214篇 |
1987年 | 164篇 |
1986年 | 170篇 |
1985年 | 185篇 |
1984年 | 141篇 |
1983年 | 100篇 |
1982年 | 119篇 |
1981年 | 123篇 |
1980年 | 117篇 |
1979年 | 97篇 |
1978年 | 81篇 |
1977年 | 144篇 |
1976年 | 229篇 |
1975年 | 90篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
P de Lonlay JC Fournet J Rahier MS Gross-Morand F Poggi-Travert V Foussier JP Bonnefont MC Brusset F Brunelle JJ Robert C Nihoul-Fékété JM Saudubray C Junien 《Canadian Metallurgical Quarterly》1997,100(4):802-807
Sporadic persistent hyperinsulinemic hypoglycemia of infancy (PHHI) or nesidioblastosis is a heterogeneous disorder characterized by profound hypoglycemia due to inappropriate hypersecretion of insulin. An important diagnostic goal is to distinguish patients with a focal hyperplasia of islet cells of the pancreas (FoPHHI) from those with a diffuse abnormality of islets (DiPHHI) because management strategies differ significantly. 16 infants with sporadic PHHI resistant to diazoxide and who underwent pancreatectomy were investigated. Selective pancreatic venous sampling coupled with peroperative surgical examination and analysis of extemporaneous frozen sections allowed us to identify 10 cases with FoPHHI and 6 cases with DiPHHI. We show here that in cases of FoPHHI, but not those of DiPHHI, there was specific loss of maternal alleles of the imprinted chromosome region 11p15 in cells of the hyperplastic area of the pancreas but not in normal pancreatic cells. This somatic event is consistent with a proliferative monoclonal lesion. It involves disruption of the balance between monoallelic expression of several maternally and paternally expressed genes. Thus, we provide the first molecular explanation of the heterogeneity of sporadic forms of PHHI such that it is possible to perform only partial pancreatectomy, limited to the focal somatic lesion, so as to avoid iatrogenic diabetes in patients with focal adenomatous hyperplasia. 相似文献
63.
Somatic hypermutation of the immunoglobulin variable genes during germinal reactions might permit the expansion of B-cell clones with unwanted (e.g. autoreactive) specificity. Here, Ernst Lindhout and colleagues propose three antigen-specific checkpoints that ensure the appropriate antigen specificity of activated B cells is maintained by regulating the activation, selection and further differentiation of B cells. 相似文献
64.
F Koumanov C Henry C Ghezzi JP Mathieu C Morin M Vidal J de Leiris M Comet D Fagret 《Canadian Metallurgical Quarterly》1997,24(6):519-525
Two anomeric analogues of glucose labelled with 123 iodine in position 6, proposed as tracers of glucose transport in vivo, have been synthesized: alpha- and beta-methyl-6-deoxy-6-iodo-D-glucopyranoside (alpha MDIG and beta MDIG). The aim of this study was to determine whether these molecules interact with the glucose transporter and whether they could be used as tracers of glucose transport in vivo. The biodistribution of alpha MDIG and beta MDIG was studied in the mouse in vivo. To determine if these two anomers enter the cell via the glucose transporter, their uptake was measured in isolated perfused rat hearts, in human erythrocytes in suspension, and in cardiomyocytes of neonatal rat in culture. Both alpha MDIG and beta MDIG had similar repartitions in the mouse: myocardial uptake averaged 7% of the injected dose/g of organ at 2 min postinjection and alpha MDIG competed with D-glucose to enter the cells. Insulin produced a 123% increase of its uptake in isolated perfused rat hearts and a 100% increase in cardiomyocytes of neonatal rat in culture. alpha MDIG uptake was lowered in the presence of glucose transport inhibitors in each experimental model. An interaction between beta MDIG and glucose transporters was observed only in human erythrocytes in suspension. Only alpha MDIG interacts with the glucose transporter, and thus could be used to estimate glucose transport in vivo. 相似文献
65.
66.
A quasi-analytical method for computing the quasi-static-TEM parameters of the generalized coplanar waveguide (GCPW) is reported. The structure is assumed to be enclosed in a rectangular frame and embedded in a layered medium. Essentially, the method is an analytically enhanced spectral domain formulation. Its application leads to virtually exact results in very short CPU times, making it suitable for CAD purposes. Although the method is somewhat more time consuming than conformal mapping approaches, it is a useful alternative because of its exactness and ability to deal with multilayer structures. © 1994 John Wiley & Sons, Inc. 相似文献
67.
68.
E La Hey J de Vries CT Langerhorst GS Baarsma A Kijlstra 《Canadian Metallurgical Quarterly》1993,116(3):327-340
After reviewing the records of 111 patients with Fuchs' heterochromic iridocyclitis, we studied the therapy and prognosis of secondary glaucoma in 30 of these 111 patients (27%) who had glaucoma or could be considered glaucoma suspects. Maximal medical therapy was unsuccessful in 22 of the 30 patients (73%). Surgical intervention (mostly trabeculectomies, half with 5-fluorouracil) successfully controlled intraocular pressure (< or = 21 mm Hg with or without medication) in 13 of the 18 operated-on patients (72%) after a mean follow-up of 26 months. All successfully operated-on patients retained a visual acuity of 20/80 or better. We had favorable results, possibly because of modern surgical techniques (use of 5-fluorouracil, sodium hyaluronate) or earlier surgical intervention, or both. 相似文献
69.
Studied how 26 senior managers and 47 senior professional technical staff (recently repatriated) of 4 US owned multinational organizations viewed their international posting, specifically with respect to career path satisfaction. Results of satisfaction scales indicate that many Ss felt under-prepared for their international assignment. It is suggested that a comprehensive international employee development program should assess, provide feedback, and coach individuals on career path, culture shock and adjustment, and performance issues prior, during, and on return from the expatriate assignment. Results suggest that opportunities exist for individual and organizational intervention. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
70.
STRONG METAL-CERAMIC JOINTS 总被引:3,自引:0,他引:3
In this paper the technology for joining metals to ceramics is reviewed. The technologies of metal powder sintering, liquid phase joining with activated brazing alloys and with ceramic frit, solid-state joining, friction welding and mechanical fixation are described. In order to put some perspective on the mechanical data given in the literature, some evaluating remarks on mechanical testing are made. 相似文献