全文获取类型
收费全文 | 1845篇 |
免费 | 0篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 123篇 |
金属工艺 | 30篇 |
机械仪表 | 25篇 |
建筑科学 | 1篇 |
矿业工程 | 8篇 |
轻工业 | 4篇 |
水利工程 | 3篇 |
石油天然气 | 27篇 |
无线电 | 6篇 |
一般工业技术 | 32篇 |
冶金工业 | 1547篇 |
原子能技术 | 33篇 |
自动化技术 | 4篇 |
出版年
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 8篇 |
2013年 | 6篇 |
2012年 | 10篇 |
2011年 | 7篇 |
2010年 | 5篇 |
2009年 | 12篇 |
2008年 | 5篇 |
2007年 | 9篇 |
2005年 | 5篇 |
2004年 | 10篇 |
2003年 | 8篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 30篇 |
1998年 | 447篇 |
1997年 | 262篇 |
1996年 | 184篇 |
1995年 | 148篇 |
1994年 | 88篇 |
1993年 | 88篇 |
1992年 | 21篇 |
1991年 | 19篇 |
1990年 | 17篇 |
1989年 | 12篇 |
1988年 | 20篇 |
1987年 | 14篇 |
1986年 | 10篇 |
1985年 | 16篇 |
1984年 | 7篇 |
1983年 | 11篇 |
1982年 | 7篇 |
1981年 | 13篇 |
1980年 | 28篇 |
1979年 | 4篇 |
1978年 | 11篇 |
1977年 | 60篇 |
1976年 | 104篇 |
1975年 | 11篇 |
1974年 | 8篇 |
1973年 | 11篇 |
1972年 | 13篇 |
1971年 | 10篇 |
1969年 | 6篇 |
1967年 | 8篇 |
1966年 | 5篇 |
1964年 | 5篇 |
1961年 | 3篇 |
排序方式: 共有1845条查询结果,搜索用时 15 毫秒
31.
32.
In this study the interaction of applied N with different irrigation schedules on grain yields and N use efficiency of wheat was investigated in two Inceptisols of the Nigerian savanna during 1978–80. Irrigation intervals ranged from 7 to 28 days at Kadawa and 5 to 10 days at Bakura while the N rates varied from 0 to 200 kg per ha. Both grain yield and N uptake increased significantly with increasing N rates at both the locations. The magnitude of increase in yield and N uptake decreased substantially when the irrigation interval became longer. This interaction was very pronounced at Bakura where the soil is highly porous, excessively drained and extremely poor in moisture retention capacity. Longer irrigation intervals produced grains with slightly higher N content but the difference was not significant. Higher N rates and fewer irrigations gave lower fertilizer N recovery. 相似文献
33.
A model of instrumental conditioning similar to the classical model (Pavlovian) is proposed. Flexion of the ipsilateral forelimb was elicited while EDS was applied to the hind limb by stimulation of the motor area of the cortex (M1); both stimuli ceased during the raising of the forelimb. Uniform combinations of this kind led to the development of forepaw flexion reactions in response to the EDS of the hind paw. Prolongation of EDS by 3 sec following cortical stimulation led to rapid extinction of the developed reactions. Thus, the possibility of the effective instrumentalization of movements induced by stimulation of the M1 is proven. This argues that the forming "instrumental" connection (drive-motor structures) is addressed directly to the M1. 相似文献
34.
AM Jackson AV Ivshina O Senko A Kuznetsova A Sundan MA O'Donnell S Clinton AB Alexandroff PJ Selby K James VA Kuznetsov 《Canadian Metallurgical Quarterly》1998,159(3):1054-1063
PURPOSE: The goal of this research was to discover new biological indicators in urine which could be used for short-term prognosis of local Bacillus Calmette-Guerin (BCG) therapy outcome in patients with superficial bladder cancer. PATIENTS AND METHODS: We measured and statistically evaluated soluble immunological molecules in urine from bladder cancer patients (n = 34) receiving BCG intravesically. Urine was collected following each of 6 weekly treatments, processed and assayed. The data base included measurements of interleukin-1 (IL-2, IL-4, IL-6, IL-10, IL-12, soluble intercellular adhesion molecule-1 (sICAM-1), tumour necrosis factor-alpha (TNF alpha), soluble CD14 (sCD14), interferon-gamma (IFN gamma), GM-CSF, volume of urine and its pH. The clinical response was evaluated by urine histology and random quadrant biopsy 3 months after the start of therapy. Patients were divided into 2 groups, with good and poor therapeutic effect. The initial complete response rate was 62% (21/34). The data base was analyzed using traditional multivariate statistical methods and a pattern recognition method which deals with combinatorial-statistical analysis (statistically weighted syndromes (SWS) method) of the gradated features. The SWS method is capable of identifying robust patterns in small "fuzzy" sets with high dimensional objects and some missing values. RESULTS: Only one parameter gave significant differences at p < 0.05, GM-CSF at instillation 6. Repeated measurement analysis of variance, backward stepwise multiple logistic regression and linear discriminant analysis failed to show any significance. However, significant differences in the structure of correlation between features in the groups with and without therapeutic effect were observed and four highly informative variables (the masses of sICAM-1, TNF alpha, sCD14 and pH) relating to 5th-6th installations were selected by SWS. These features provided accurate individual prediction of therapeutic outcome for all our patients. Cross-validation analysis and computer simulation showed the statistically significant stability of the prediction. CONCLUSION: We have selected a set of urinary variables that could be considered as a perspective combination of indicators (syndromes) of outcome of pre-operation BCG therapy of patients with superficial bladder cancer. A larger patient database will provide testing and evaluation of the biological and clinical significance of selected features. The computational syndrome-disease approach should be applicable for the solution of decision-making problems for management of cancer. 相似文献
35.
AV Chalyshev 《Canadian Metallurgical Quarterly》1998,29(3):92-104
Dietary character of ruminants in the north is principally different between "nonselective" (cattle, sheep) and "selective" (reindeer, moose) species. Due to the developed polyfunctioning, forestomach in ruminants, primarily rumen and reticulum, are involved in the homeostasis formation in enteral and interior mediums, nutrients deposition and recirculation. That provides efficiency in utilization of deficient in nutrients forage and body reserves of wild ruminants during the winter. The original functional organization of absorption processes and nutrients recirculation across the multilayer epithelium of forestomach also promotes realization of the two levels metabolism during the year and adaptation of wild ruminants to season dynamics of nutrition. 相似文献
36.
PK Aianot AG Aminev SV Bezborodova AV Shcherbakov SK Starov VV Drygin AA Gusev 《Canadian Metallurgical Quarterly》1998,51(2):20-24
The paper analyzes the standard legal and methodological assurance of the quality and safety of animal food raw materials and foodstuffs (meat, meat products, fish, shellfish, crayfish and their processing products) by the parasitic purity rates according the requirements under the Russian Federation's laws "On Sanitary and Epidemiological Well-Being of the Population", "On Protection of Consumer's Rights", "On Certification of Products and Services", those of SanPiN, such as 2.3.2.560-96 "Sanitary Requirements for the Quality and Safety of Food Raw Materials and Foodstuffs" and 3.2.569-96 "Prevention of Parasitic Diseases in the Russian Federation". 相似文献
37.
A new derivation of the scale effect equation for polymer fibers is proposed. The equation is: AL
–, where is the average strength of the fiber; L is the length of the fiber; A and are coefficients. The equation was obtained from the general premises of scale effect theory without indication of the concrete form of the probability function F(S).Ukrainian Scientific-Research Institute of Polymer Fibers, Kiev. Translated from Khimicheskie Volokna, No. 4, pp. 34–36, July–August, 1992. 相似文献
38.
Nondestructive testing of the strength of materials and structures is based on the evaluation of representative strength indices that allow forecasting of the instant that destruction will occur. Flaws in a material and complexities in a structure lead to nonuniformities in their structural, stressed-strained, and strength states, to the reduction of the testability of objects, and the necessity of increasing their strength margin. The criteria for determining the kind and nonuniformity of the strength state of structural materials are formulated, a technique for qualitative evaluation of the degree of the strength nonuniformity is considered, and the correlations of different acoustic-emission and geometric strength characteristics, which were obtained by a nondestructive method, are compared to the durability of specimens. 相似文献
39.
我们非常感激你对儿音响产品的关心,并且希望它能成为你家庭音响和家庭影院中的一部分。当我们进入家庭音响市场的时候,我们公司承诺会以性能和品质的最高标准来创造产品。我们相信你会从Fathom@或者Gofham中的每个细节中看到儿音响对品质的承诺,但最重要的是,我们相信你会在每次欣赏电影和享受音乐的时候都会感受得到。 相似文献