全文获取类型
收费全文 | 704336篇 |
免费 | 9162篇 |
国内免费 | 2106篇 |
专业分类
电工技术 | 12993篇 |
综合类 | 671篇 |
化学工业 | 105335篇 |
金属工艺 | 26707篇 |
机械仪表 | 20457篇 |
建筑科学 | 17379篇 |
矿业工程 | 2942篇 |
能源动力 | 19774篇 |
轻工业 | 61416篇 |
水利工程 | 6798篇 |
石油天然气 | 11415篇 |
武器工业 | 45篇 |
无线电 | 83406篇 |
一般工业技术 | 137170篇 |
冶金工业 | 136481篇 |
原子能技术 | 13872篇 |
自动化技术 | 58743篇 |
出版年
2022年 | 4171篇 |
2021年 | 6384篇 |
2020年 | 4666篇 |
2019年 | 5897篇 |
2018年 | 10045篇 |
2017年 | 9864篇 |
2016年 | 10358篇 |
2015年 | 7115篇 |
2014年 | 11935篇 |
2013年 | 32583篇 |
2012年 | 18854篇 |
2011年 | 26074篇 |
2010年 | 20637篇 |
2009年 | 23290篇 |
2008年 | 23923篇 |
2007年 | 23501篇 |
2006年 | 20651篇 |
2005年 | 18565篇 |
2004年 | 17961篇 |
2003年 | 17839篇 |
2002年 | 16892篇 |
2001年 | 17272篇 |
2000年 | 16019篇 |
1999年 | 16973篇 |
1998年 | 43433篇 |
1997年 | 30405篇 |
1996年 | 23339篇 |
1995年 | 17587篇 |
1994年 | 15367篇 |
1993年 | 15150篇 |
1992年 | 10899篇 |
1991年 | 10360篇 |
1990年 | 10107篇 |
1989年 | 9678篇 |
1988年 | 9120篇 |
1987年 | 8027篇 |
1986年 | 7874篇 |
1985年 | 8718篇 |
1984年 | 8137篇 |
1983年 | 7388篇 |
1982年 | 6920篇 |
1981年 | 6893篇 |
1980年 | 6632篇 |
1979年 | 6379篇 |
1978年 | 6047篇 |
1977年 | 7351篇 |
1976年 | 9736篇 |
1975年 | 5149篇 |
1974年 | 4904篇 |
1973年 | 4947篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
141.
C Llanes P Gabant M Couturier Y Michel-Briand 《Canadian Metallurgical Quarterly》1994,176(11):3403-3407
The Inc A/C plasmids, like Inc P and Inc Q plasmids, have a broad host range. However, their maintenance functions remain to be studied. An autoreplicative region of 2.79 kb named RepA/C, able to replicate both in the family Enterobacteriaceae and in Pseudomonas spp., was isolated and sequenced. The stability, copy number, and incompatibility expression of this replicon were determined. RepA/C and a nonautoreplicative fragment of 16 kb of this replicon were used as probes and showed specific hybridizations with the Inc P3-A/C plasmids from Pseudomonas spp. and members of the Enterobacteriaceae. These probes could be used as tools for identification of the plasmids of this epidemiologically important Inc group. 相似文献
142.
143.
Garner H.R. Balog R.P. Luebke K.J. 《IEEE engineering in medicine and biology magazine》2002,21(4):123-125
Given the enormous size of the genome and that there are potentially many other types of measurements we need to do to understand it, it has become necessary to pick and choose one's targets to measure because it is still impossible to evaluate the entire genome all at once. What has emerged is a need to have rapidly customizable microarrays. There are two dominant methods to accomplish custom microarray synthesis, Affymetrix-like microarrays manufactured using light projection rather than semiconductor-like masks used by Affymetrix to mass manufacture their GeneChip/sup TM/ arrays now, or the ink-jet printing method employed by Agilent. The manufacture of these custom Affymetrix-like microarrays can now be done on a digital optical chemistry (DOC) machine developed at the University of Texas Southwestern Medical Center, and this method offers much higher feature numbers and feature density than is possible with ink-jet printed arrays. On a microarray, each feature contains a single genetic measurement. The initial DOC prototype has been described in several publications, but that has now led to a second-generation machine. This machine reliably produces a number of arrays daily, has been deployed against a number of biomedical questions, is being used in new ways and has also led to a number of spin-off technologies. 相似文献
144.
A new system based on the harnessing of solar and wind power is presented for heat dissipation in air conditioning facilities. The innovation offered by the new system is the integration of two well-known subsystems: a cooling tower and a solar chimney which increases the air flow without the use of electric power. The system is described and presented together with a model for its study. The field data acquired from the prototype built in southern Spain establishes the actual potential of the system, which provides a new approach to a sustainable technological development. 相似文献
145.
G.D. Wignall R.W. Hendricks W.C. Koehler J.S. Lin M.P. Wai E.L. Thomas R.S. Stein 《Polymer》1981,22(7):886-889
A series of small angle neutron scattering measurements on blends of normal polystyrene (PSH) and labelled (deuterated) polystyrene (PSD) have been made with concentrations of PSD from 5 to 50 mol %. It is shown that the single chain form factor of the polymer in bulk can be obtained from a single concentration measurement for any concentration of labelled molecules, providing the molecular weights of the parent and labelled molecules are the same and the molecular weight distributions are narrow. 相似文献
146.
Rapeseed protein concentrate (RC), prepared with 2% hexameta-phosphate, was tested for its functionality and performance in some foods. The RC had good nitrogen solubility, fat absorption, emulsification, and whipping capacities but poor water absorption and gelling properties. It increased the emulsion stability, and protein but lowered the fat content of wieners. It also increased the cooking yield, reduced the shrinkage and tenderized meat patties. Results were similar to soybean isolate except for the poorer color and flavor. The cooking yield of RC supplemented wieners was less than the all-meat control and soybean-supplemented wieners. A 9% RC dispersion mixed with an equal volume of eggwhite produced a meringue of comparable stability and texture to that of eggwhite alone. 相似文献
147.
The properties of a spinel copper cobaltite obtained by thermal decomposition of mixed nitrates of both metals at 350°C and normal pressure are described. It has been shown that the maximum copper content (x) in the spinel CuxCo3?xO4 does not exceed 0.9. When the copper amount in the initial mixture is higher a second phase CuO is formed. The copper ions are distributed over the A- and the B-sites of the spinel lattice, i.e. the spinel is partially inverted. Such a model explains well the data obtained about the lattice parameter, IR-absorption and the magnetic susceptibility of the samples with different x. 相似文献
148.
M. D. Korostash 《Drying Technology》1985,3(4):603-611
The paper presents the results of research in the convection drying of unidirectional glass fibre bobbins on the basis of which the relations are suggested required to calculate the process of drying in the design of drying equipment. 相似文献
149.
Field surveys of a series of conjugated diunsaturated straight-chain primary alcohols, acetates, and aldehydes (dienes), including the 3,5-dode-cadienyl, 8,10-dodecadienyl, 3,5-tetradecadienyl, 8,10-tetradecadienyl, 9,11-tetradecadienyl, and 10,12-tetradecadienyl primary alcohols, acetates, and most aldehydes, and the related monounsaturated straight-chain primary alcohols, acetates, and aldehydes (monoenes), including the 3-dodecadienyl alcohol and acetates, attracted the following species from the title families. Diene attractants have been demonstrated for at least onePhyllonorycter sp.,Chionodes lugubrella (Fabr.),Leptostales ferruminaria (Zell.),Drepana bilineata (Pack.),Pyrausta fodinalis (Led.),Notocelia purpurissatana Heinr.,Phaneta alterana Heinr. Monoene attractants were demonstrated forHedya separatana (Kft.),Cydia fletcherana (Kft.),Barbara mappana Free.,Ancylis burgessiana (Zell.),Ancylis nubeculana Clem.,Evippe prunifoliella Cham.,Phlyctaenia coronata tertialis (Gn.), aChionodes sp., a Gelechiidae sp., and an unidentifiedPhyllonorycter sp. Replicated field experiments showed attraction-inhibition relationships for most species. Electroantennagram data are presented forLeptostales ferruminaria andDrepana bilineata. 相似文献
150.
Naphthalene-2,3-dicarboxaldehyde (NDA) has been investigated as a new derivatizing reagent for the electrochemical detection of tagged amino acids. Gradient elution allowed for the separation of 18 NDA-derivatized amino acids on an open tubular liquid chromatography column in less than 50 min. Gradient elution and electrochemical detection were found to be compatible. A detection limit of 36 amol was obtained for the asparagine-NDA derivative. The usefulness of this technique for quantitation was demonstrated by the analysis of the NDA-tagged hydrolysis products from bovine chymotrypsinogen. 相似文献