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71.
Density-based multiscale data condensation 总被引:10,自引:0,他引:10
Mitra P. Murthy C.A. Pal S.K. 《IEEE transactions on pattern analysis and machine intelligence》2002,24(6):734-747
A problem gaining interest in pattern recognition applied to data mining is that of selecting a small representative subset from a very large data set. In this article, a nonparametric data reduction scheme is suggested. It attempts to represent the density underlying the data. The algorithm selects representative points in a multiscale fashion which is novel from existing density-based approaches. The accuracy of representation by the condensed set is measured in terms of the error in density estimates of the original and reduced sets. Experimental studies on several real life data sets show that the multiscale approach is superior to several related condensation methods both in terms of condensation ratio and estimation error. The condensed set obtained was also experimentally shown to be effective for some important data mining tasks like classification, clustering, and rule generation on large data sets. Moreover, it is empirically found that the algorithm is efficient in terms of sample complexity 相似文献
72.
2-(2,4-Dimethylphenyl)indan-1,3-dione was shown to be a potent hypolipidemic agent in rodents, lowering significantly both
serum cholesterol and triglyceride levels at 20 mg/kg/day. The agent in vivo inhibited the enzymatic activities of ATP-dependent
citrate lyase, acetyl-CoA synthetase, cholesterol-7α-hydroxylase, acyl-CoA cholesterol acyl transferase,sn-glycerol-3-phosphate acyl transferase and phosphatidylate phosphohydrolase. Tissue lipid levels of liver and small intestine
also were reduced by the agent. The rat serum lipoprotein lipid content was modulated by the drug, which should be favorable
for the removable of cholesterol from peripheral tissue for conduction to the liver for clearance from the body. Low density
lipoprotein (LDL) cholesterol levels were reduced after treatment, which suggests that the agent potentially reduces deposition
of cholesterol in plaques. If chemotherapy for atherosclerosis is to be successful, then the high density lipoprotein (HDL)
cholesterol level needs to be elevated more than 16% to 25%, the level produced by current hypolipidemic agents. 2-(2,4-Dimethylphenyl)-indan-1,3-dione
offers a 75% increase in HDL cholesterol levels and a 30% reduction of LDL cholesterol levels with a suppression of de novo
synthesis of lipids and a reduction of tissue cholesterol deposition. 相似文献
73.
EB Nikol'skaia OV Iagodina BA Grinberg MM Dianova 《Canadian Metallurgical Quarterly》1998,70(3):50-56
Isolation of highly purified and highly molecular monoamine oxidase (MAO) from pig liver mitochondria have been worked out. Specific activity of isolated preparation is 2700 times higher than of original mitochondria homogenate. Enzyme solubilization by digitonin, affinity chromatography purification and ultrafiltration underlie this method. MAO catalytic properties changing during the process of purification by different methods have been investigated. Substrate specificity was studied; kinetic parameters of enzymatic desemination were calculated. 相似文献
74.
V Jha MS Murthy HS Kohli K Sud KL Gupta K Joshi V Sakhuja 《Canadian Metallurgical Quarterly》1998,20(6):845-850
In vitro selection can be used to generate nucleic acid ligands (aptamers) to target molecules ranging in size and structure from cations to cells. However, the selection process is repetitive and time-consuming. We have automated a protocol for in vitro selection using an augmented Beckman Biomek 2000 pipetting robot. The automated selection procedure requires the integration of four devices and the optimization of four molecular biology methods, and is one of the most complex automated protocols attempted to date. Initial attempts at selection yielded robust replication parasites, but optimization of the automated selection procedure suppressed the emergence of these parasites and led to the selection of true nucleic acid ligands. Automated selection can now be used to generate nucleic acid aptamers in days rather than weeks or months. 相似文献
75.
76.
77.
In this note we study the stability aspects of CSDT methods for solving parabolic partial differential equations. We define two types of stability and discuss the stability of various CSDT methods. 相似文献
78.
We present in this paper a unified approach to the crosstalk interference problem arising in PCM transmission on paired cables. For bipolar signaling, and three types of commonly used channel shaping, viz., cosine, raised cosine, and Gaussian, we present the minimum average near-end crosstalk (NEXT) and far-end crosstalk (FEXT) loss requirements at any transmission rate as a function of repeater spacing and number of interfering pairs so as to meet a desired error rate objective. This will aid in indicating if new cables need to be developed for a proposed rate of transmission or, for a given cable, the error margin available for degradations other than crosstalk can be readily determined. Extension to other coding schemes is indicated, and crosstalk compatibility is examined for mixedT systems, such asT1 ,T1C , andT2 . Graphical results are presented to readily aid in system design of anyT carrier with repeater spacings up to 70 dB. 相似文献
79.
Experimental data on the diffusion of fluorescent dye plumes were obtained in the nearshore zone of the Great Lakes. The transport and diffusion of continuous dye plumes may be studied either in a frame of reference moving with the centre of gravity of the plume or in a frame of reference fixed to the stationary source. Conventionally, the former is referred to as “relative” diffusion and the latter as “absolute” diffisuion. The inter-link between the two concepts is explained by the random movements of the centre of gravity of the diffusing dye plume usually referred to as the “meandering”.In the past, experimental data from continuous dye plumes in coastal currents have been used to study “relative” diffusion, neglecting the random movements of the centre of gravity. In reality, however, “meandering” appears to be a more efficient agency than “relative” diffusion from the practical point of view of dispersing effluents over larger volume of the water body.In the present analysis, particular attention is given to delineate the two component physical processes of “relative” diffusion and “meandering” diffusion, by extended sampling of the dye plume to cover time scales of both the processes. Calculated horizontal eddy diffusivity Ky in “absolute” diffusion is greater by a factor of 2 as compared to “relative” diffusion. Very high peak/mean concentration ratios observed as the centre of the plume are a direct result of “meandering” due to large scale turbulent eddies. 相似文献
80.