全文获取类型
收费全文 | 8830篇 |
免费 | 22篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 9篇 |
综合类 | 5篇 |
化学工业 | 118篇 |
金属工艺 | 11篇 |
机械仪表 | 4篇 |
建筑科学 | 12篇 |
矿业工程 | 1篇 |
能源动力 | 9篇 |
轻工业 | 58篇 |
水利工程 | 1篇 |
石油天然气 | 4篇 |
武器工业 | 1篇 |
无线电 | 73篇 |
一般工业技术 | 39篇 |
冶金工业 | 8439篇 |
原子能技术 | 2篇 |
自动化技术 | 67篇 |
出版年
2022年 | 6篇 |
2021年 | 12篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 13篇 |
2015年 | 11篇 |
2014年 | 19篇 |
2013年 | 29篇 |
2012年 | 20篇 |
2011年 | 20篇 |
2010年 | 13篇 |
2009年 | 25篇 |
2008年 | 22篇 |
2007年 | 23篇 |
2006年 | 30篇 |
2005年 | 20篇 |
2004年 | 18篇 |
2003年 | 26篇 |
2002年 | 8篇 |
2001年 | 14篇 |
2000年 | 14篇 |
1999年 | 288篇 |
1998年 | 2712篇 |
1997年 | 1497篇 |
1996年 | 964篇 |
1995年 | 552篇 |
1994年 | 425篇 |
1993年 | 533篇 |
1992年 | 64篇 |
1991年 | 103篇 |
1990年 | 101篇 |
1989年 | 88篇 |
1988年 | 94篇 |
1987年 | 95篇 |
1986年 | 97篇 |
1985年 | 66篇 |
1983年 | 9篇 |
1982年 | 35篇 |
1981年 | 37篇 |
1980年 | 77篇 |
1979年 | 2篇 |
1978年 | 13篇 |
1977年 | 182篇 |
1976年 | 433篇 |
1975年 | 9篇 |
1963年 | 2篇 |
1955年 | 7篇 |
1954年 | 1篇 |
排序方式: 共有8853条查询结果,搜索用时 15 毫秒
51.
We have investigated factors influencing the survival of women with early breast cancer in Scotland. In a retrospective study, clinical, treatment and 'service' factors, e.g. surgical case load, deprivation and geographical area (health board of first treatment) were recorded from hospital records. A total of 2148 women with invasive breast cancer diagnosed in 1987 were identified from the Scottish Cancer Registry, of whom 1619 without metastases at diagnosis underwent surgery as part of their primary treatment. In a multivariate analysis, clinical factors (age, clinical stage, pathological tumour size, node status and oestrogen receptor status) all influenced survival. After allowing for these clinical factors, surgical case load and deprivation did not have statistically significant effects on survival. By contrast, health board did affect survival. This was explained in part by the selection of patients for surgery. There appeared, however, to be a residual effect that may be related to differences in the use of adjuvant systemic treatment among the different health boards. We conclude that, in Scotland, geographical variation in both surgical and non-surgical treatment has a greater effect on variability in survival for women with breast cancer than surgical case load and deprivation. 相似文献
52.
Mantle cell lymphoma (MCL) patients represent a difficult problem, sometimes to establish the diagnosis but mostly because of their refractoriness to standard lymphoma treatments. Which treatments to apply and to whom is not yet defined. In this study, we attempted to analyze the clinical features, to identify the major prognostic factors, and to evaluate the outcome of 121 MCL patients treated in our institution between 1979 and 1997. Clinical data, treatment modalities, and International Prognostic Index (IPI) score were evaluated. Median age was 63 years. Patients usually presented with advanced stage disease (87%), disseminated lymph nodes (57%), bone marrow involvement (79%), but with a good performance status (PS) (81%). Lymphocytosis >4000/microl and/or peripheral blood involvement was present in 36% of cases, and gastrointestinal disease in 18%. The t(11;14)(q13;q32) and/or bcl-1 rearrangement was detected in 47/57 studied cases. Median overall survival (OS) was 3.12 years and a longer survival was significantly associated with younger age (<70 years), good PS (<2), localized disease (stage I-II), fewer than two extra-nodal sites, absence of spleen or peripheral blood involvement, normal serum LDH and beta2-microglobulin levels, and hemoglobin level greater than 12 g/dl. However, the IPI failed to identify patients with longer OS and in a multiparametric analysis, only older age, hemoglobin less than 12 g/dl, poor PS, and blood involvement were associated with a poorer outcome. Treatment modalities had no impact on survival with 75% of patients relapsing or progressing. Our data showed that the poor outcome of MCL patients is mainly related to adverse patient characteristics, a highly disseminated tumor, and some unknown parameters associated with the refractoriness to standard therapy. 相似文献
53.
54.
55.
B Elliott C Richardson J Winderbaum JA Nickoloff M Jasin 《Canadian Metallurgical Quarterly》1998,18(1):93-101
A new assay termed the dome disappearance method for classical swine fever virus (CSFV) using FS-L3 cells with serum-free culture medium was developed. The CSFV live vaccine GPE- strain grows well and shows a slight cytopathic effect (CPE) in FS-L3 cells. This CPE results in the disappearance of the unique fluid-filled multicellular domes on a single monolayer of FS-L3 cells. By using this phenomenon, dome disappearance, as a marker of infection, it was possible to determine the titers of CSFV and its neutralizing antibody. The virus titer determined by this method shows a good correlation with that determined by immunochemical and interference methods. Furthermore, the amount of neutralizing antibody measured by this method also correlated with that measured by the Exaltation of Newcastle Disease Virus (END) neutralizing method. The dome disappearance method developed in this experiment is a simple and safe procedure and has the great advantage that bovine serum, which may contain antibody against bovine viral diarrhea virus, is not necessary for the cultivation of FS-L3 cells. 相似文献
56.
Efficacies of the 5-hydroxytryptamine (serotonin) 5-HT3 receptor (5-HT3R) agonists 2-methyl-5-HT, dopamine, and m-chlorophenylbiguanide on 5-HT3R native to N1E-115 cells and on homopentameric 5-HT3R expressed in Xenopus oocytes were determined relative to that of 5-HT. Efficacies of 2-methyl-5-HT and dopamine on 5-HT3R native to differentiated N1E-115 cells are high (54 and 36%) as compared with their efficacies on homopentameric 5-HT3R-A(L) and 5-HT3R-A(S) receptors expressed in oocytes (4-8%). m-Chlorophenylbiguanide does not distinguish between 5-HT3R in N1E-115 cells and in oocytes. The distinct pharmacological profile of 5-HT3R native to differentiated N1E-115 cells is conserved when poly(A)+ mRNA from these cells is expressed in oocytes. The results indicate that, apart from the known 5-HT3R subunits, N1E-115 cells express additional proteins involved in 5-HT3R function. 相似文献
57.
58.
In this article, we present the findings of our study into the thermal decomposition of the alga Ulva, which can cause serious problems due to its proliferation in certain seas. Its use as a human foodstuff or other similar applications is limited; however, it could be used as a filling or reinforcement material in the manufacture of composite materials. Since the production processes of such materials usually require heating, the thermal stability of this polymeric material needs to be known, and this is the objective of this work. For this reason, we have studied the thermal decomposition in an air atmosphere using thermogravimetry (TG). On the one hand, we evaluated the thermal stability temperatures of the seaweed; and on the other, we determined the kinetic parameters of the alga's two main decomposition reactions, using an n‐order integral kinetic model. It was, therefore, necessary to calculate the best order of reaction. Finally, we determined a series of characteristic temperatures related to the beginning and the end of each of the thermal decomposition reactions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1913–1922, 2004 相似文献
59.
Carrasco C Rosu F Gabelica V Houssier C De Pauw E Garbay-Jaureguiberry C Roques B Wilson WD Chaires JB Waring MJ Bailly C 《Chembiochem : a European journal of chemical biology》2002,3(12):1235-1241
The structural selectivity of the DNA-binding antitumor drug ditercalinium was investigated by competition dialysis with a series of nineteen different DNA substrates. The 7H-pyridocarbazole dimer was found to bind to double-stranded DNA with a preference for GC-rich species but can in addition form stable complexes with triplex and quadruplex structures. The preferential interaction of the drug with four-stranded DNA structures was independently confirmed by electrospray mass spectrometry and a detailed analysis of the binding reaction was performed by surface plasmon resonance (SPR) spectroscopy. The BIAcore SPR study showed that the kinetic parameters for the interaction of ditercalinium with the human telomeric quadruplex sequence are comparable to those measured with a duplex sequence. Slow association and dissociation were observed with both the quadruplex and duplex structures. The newly discovered preferential binding of ditercalinium to the antiparallel quadruplex sequence d(AG(3)[T(2)AG(3)](3)) provides new perspectives for the design of drugs that can bind to human telomeres. 相似文献
60.
Cristhian Carrasco Carlos Solano José Mauricio Peñarrieta Henrique Macedo Baudel Mats Galbe Gunnar Lidén 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(12):1723-1725
A pentose‐rich hydrolysate fraction obtained by extraction of steam‐pretreated sugarcane bagasse was analysed with regard to dissolved phenolics. The liquid obtained after steam pretreatment (2% SO2 (w/w) at 190 °C for 5 min) was divided into two parts: one containing dissolved compounds originating from hemicellulose (with xylose as the dominating compound), and the other containing predominantly dissolved compounds originating from lignin. Using nuclear magnetic resonance, the main dissolved compounds originating from lignin were identified as the glycosylated aromatics, 5‐O‐(trans‐feruloyl)‐L‐Arabinofuranose and 5‐O‐(trans‐coumaroyl)‐L‐Arabinofuranose, together with p‐coumaric acid and small amounts of more common free phenolics such as p‐hydroxybenzaldehyde, p‐hydroxybenzoic acid and vanillin. The phenolic compounds were analysed and quantified using reversed‐phase high‐performance liquid chromatography. The findings show that SO2 steam explosion opened up new degradation pathways during lignin degradation. Copyright © 2012 Society of Chemical Industry 相似文献