全文获取类型
收费全文 | 3378篇 |
免费 | 24篇 |
专业分类
电工技术 | 20篇 |
综合类 | 1篇 |
化学工业 | 255篇 |
金属工艺 | 28篇 |
机械仪表 | 13篇 |
建筑科学 | 32篇 |
矿业工程 | 1篇 |
能源动力 | 14篇 |
轻工业 | 69篇 |
水利工程 | 13篇 |
无线电 | 104篇 |
一般工业技术 | 175篇 |
冶金工业 | 2510篇 |
原子能技术 | 8篇 |
自动化技术 | 159篇 |
出版年
2018年 | 15篇 |
2017年 | 13篇 |
2015年 | 13篇 |
2014年 | 12篇 |
2013年 | 45篇 |
2012年 | 34篇 |
2011年 | 49篇 |
2010年 | 26篇 |
2009年 | 27篇 |
2008年 | 34篇 |
2007年 | 48篇 |
2006年 | 28篇 |
2005年 | 27篇 |
2004年 | 19篇 |
2003年 | 34篇 |
2002年 | 26篇 |
2001年 | 28篇 |
2000年 | 26篇 |
1999年 | 105篇 |
1998年 | 829篇 |
1997年 | 484篇 |
1996年 | 290篇 |
1995年 | 155篇 |
1994年 | 156篇 |
1993年 | 158篇 |
1992年 | 40篇 |
1991年 | 36篇 |
1990年 | 18篇 |
1989年 | 32篇 |
1988年 | 27篇 |
1987年 | 28篇 |
1986年 | 19篇 |
1985年 | 29篇 |
1984年 | 17篇 |
1983年 | 15篇 |
1982年 | 20篇 |
1981年 | 25篇 |
1980年 | 26篇 |
1979年 | 12篇 |
1978年 | 15篇 |
1977年 | 56篇 |
1976年 | 113篇 |
1975年 | 16篇 |
1974年 | 16篇 |
1973年 | 13篇 |
1972年 | 16篇 |
1971年 | 14篇 |
1970年 | 13篇 |
1969年 | 19篇 |
1968年 | 13篇 |
排序方式: 共有3402条查询结果,搜索用时 15 毫秒
71.
AS Stein MR O'Donnell A Chai GM Schmidt A Nademanee PM Parker EP Smith DS Snyder A Molina DE Stepan R Spielberger G Somlo KA Margolin N Vora J Lipsett J Lee J Niland SJ Forman 《Canadian Metallurgical Quarterly》1996,14(8):2206-2216
PURPOSE: To evaluate in a prospective study the efficacy of autologous bone marrow transplantation (BMT) in adult patients with acute myelogenous leukemia (AML) in first remission, using a single course of high-dose Cytarabine (HD Ara-C) consolidation therapy as in vivo purging. PATIENTS AND METHODS: Sixty consecutive adult patients with AML in first complete remission (CR) were treated with HD Ara-C consolidation therapy as a method of in vivo purging before marrow collection. High-dose therapy consisted of fractionated total-body irradiation (FTBI) 12 Gy, intravenous etoposide 60 mg/kg, and cyclophosphamide 75 mg/kg, followed by reinfusion of cryopreserved marrow. RESULTS: Sixty patients underwent consolidation treatment with HD Ara-C with the intent to treat with autologous BMT. Sixteen patients were unable to proceed to autologous BMT (10 patients relapsed, one died of sepsis, one developed cerebellar toxicity, two had inadequate blood counts, and two refused). Forty-four patients underwent autologous BMT and have a median follow-up time of 37 months (range, 14.7 to 68.7) for patients who are alive with no relapse. The cumulative probability of disease-free survival (DFS) at 24 months in the intent-to-treat group is 49% (95% confidence interval [CI], 37% to 62%) and in those who actually underwent autologous BMT is 61% (95% CI, 46% to 74%). The probability of relapse was 44% (95% CI, 31% to 58%) and 33% (95% CI, 20% to 49%) for the intent-to-treat and autologous BMT patients, respectively. CONCLUSION: This approach offers a relatively high DFS rate to adult patients with AML in first CR. The results of this study are similar to those achieved with allogeneic BMT. 相似文献
72.
KM Ebert 《Canadian Metallurgical Quarterly》1998,42(7):1003-1008
Conformational effects and affinities of VP-16 (etoposide) and its derivatives to DNA in the presence of Cu(II) ion were examined by circular dichroic (CD) spectra. The Cu(II)/Cu(I) redox kinetics and the hydroxyl radical (.OH) generation from the Cu(II)-complexes were estimated by the stopped-flow kinetics. Based on the results, DNA-cleaving activity of Cu(II)-complexes of VP-16 has been shown to be related with binding affinity of the complex to DNA, Cu(II)/Cu(I) redox and .OH generation, emphasising the mechanism of generated .OH attack to DNA. 相似文献
73.
Teachers are frequently cited as experiencing a high rate of vocal dysfunction (1-7). Despite considerable research in the area of voice problems in teachers, the prevalence of voice disorders in this group is unknown. This study investigated the prevalence of self-reported voice problems in teachers using a mail survey of a simple random sample of 1168 state school teachers (preschool-Grade 12) in South Australia. As part of the survey, teachers were asked to report voice problems for the day of the survey, during the current teaching year, and during their careers. The response rate was 75%, with 16% of teachers reporting voice problems on the day of the survey, 20% reporting problems during the current teaching year, and 19% reporting problems at some time during their career. Females were twice as likely as males to report voice problems. These findings clearly indicate a need for further investigation of the causes of vocal dysfunction in teachers and for the development of educational programs aimed at preventing voice problems in this group of professional voice users. 相似文献
74.
Assessing obesity: classification and epidemiology 总被引:1,自引:0,他引:1
Obesity is generally defined as a body mass index (BMI) of 30 kg/m2 and higher. Overweight is defined as a BMI between 25 and 30 kg/m2. The prevalence varies considerably between countries, and between regions within countries. It is estimated that more than half of adults aged 35-65 living in Europe are either overweight or obese. Overweight is more common among men than among women but obesity is more common among women. The prevalence of obesity in Europe is probably in the order of 10-20% in men and 15-25% in adult women. In most European countries who have reliable data on time-trends the prevalence of obesity seems to be increasing. In most European countries, obesity is usually inversely associated with socio-economic status, particularly among women. New classifications of overweight may be based on cut-off points for simple anthropometric measures which reflects both total adiposity as well as abdominal fatness. 相似文献
75.
76.
Small molecule receptor-binding is dominated by weak, non-covalent interactions such as van-der-Waals hydrogen bonding or electrostatics. Calculating these non-covalent ligand-receptor interactions is a challenge to computational means in terms of accuracy and efficacy since the ligand may bind in a number of thermally accessible conformations. The conformational rotamer ensemble sampling tool (CREST) uses an iterative scheme to efficiently sample the conformational space and calculates energies using the semi-empirical ‘Geometry, Frequency, Noncovalent, eXtended Tight Binding’ (GFN2-xTB) method. This combined approach is applied to blind predictions of the modes and free energies of binding for a set of 10 drug molecule ligands to the cucurbit[n]urils CB[8] receptor from the recent ‘Statistical Assessment of the Modeling of Proteins and Ligands’ (SAMPL) challenge including morphine, hydromorphine, cocaine, fentanyl, and ketamine. For each system, the conformational space was sufficiently sampled for the free ligand and the ligand-receptor complexes using the quantum chemical Hamiltonian. A multitude of structures makes up the final conformer-rotamer ensemble, for which then free energies of binding are calculated. For those large and complex molecules, the results are in good agreement with experimental values with a mean error of 3 kcal/mol. The GFN2-xTB energies of binding are validated by advanced density functional theory calculations and found to be in good agreement. The efficacy of the automated QM sampling workflow allows the extension towards other complex molecular interaction scenarios. 相似文献
77.
Christopher L Brown Gillian Bushell Michael W Whitehouse DS Agrawal SG Tupe KM Paknikar Edward RT Tiekink 《Gold bulletin》2007,40(3):245-250
Nanosized gold particles (27 +/− 3 nm) have been proven to be effective in ameliorating the symptoms of mycobacterial-, collagen-
and pristane-induced arthritis in rat models. This contrasts with the drug sodium aurothiomalate that was only effective against
mycobacterial-induced arthritis but not to the same extent as Au0. Gold in the traditional Indian Ayurvedic medicine,Swarna bhasma (gold ash), has been characterized as globular particles of gold with an average size of 56–57 nm. 相似文献
78.
The reaction of H atoms (produced by nanosecond pulse radiolysis) with ferri-cytochrome-c in aqueous solution results in the second order formation of an absorption spectrum due to the addition of H atoms to the enzyme protein. This spectrum is not specific to the iron moiety. The rate constant of the addition is 1×1010M?1 sec?1. This is followed by two first order intramolecular processes with specific rates of ~ 1×105 sec?1 and ~ 2×104 sec?1. In these processes, specific spectra related to the α and β bands of ferro-cytochrome-c appear. The results are interpreted to show reduction equivalent transfer through the protein to the iron moiety. 相似文献
79.
W. Stein H. Weiß O. Koch P. Neuhausen H. Baumann 《European Journal of Lipid Science and Technology》1970,72(11):956-959
Preparation of Esters of α-Sulfo-Fatty Acids A process for the continuous α-sulfonation of saturated fatty acid esters with SO3 was worked out and a special bleaching process was developed for these products. The conversion, i. e. the degree of sulfonation is of the order of 95–99%. Solvents, further processing steps or purification operations for the separation of by-products are not required. 相似文献
80.
In principle, the oil milling process is straightforward. The wide variety of equipment in use reflects, however, a multiparametric
process. The main limiting parameters are kind of seed, oil content, particle strength, particle structure, temperature, moisture,
particle size, residence time, mechanical forces, etc. Additionally, the seed specific parameters vary not only between kinds
of seed but also for the same seed, due to different conditions in climate, soil, and harvesting. Therefore, equipment design
must be widely based on statistical averages of the limiting parameters. In other words, exact precalculation of the single
technological steps is impossible. As a consequence, for more than 5,000 years, the oil milling process has been in the stage
of being optimized. The acutal technical standard is very satisfying, but there is still a strong need for further research
and development. Currently, as in the past, the oil milling process seems to be not so much a science as an art. 相似文献