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911.
Kha Tuyen Chan Nguyen Cong Thanh Tran Luyen Thi Truong Trung Tan 《Food science and biotechnology》2021,30(12):1519-1526
Food Science and Biotechnology - The plant Morinda citrifolia L. (Noni) has been the subject of several recent research due to its positive impact on the treatment and prevention of a variety of... 相似文献
912.
To improve the robustness and reliability of wireless transmissions, two complementary link adaptation techniques are employed: adaptive modulation and coding (AMC) at the physical layer and hybrid automatic retransmission request (HARQ) at the medium access control layer. Because of their effectiveness in combating errors induced by the wireless channel, AMC and HARQ are now integral components of most emerging broadband wireless system standards, for example, LTE and WiMAX. Spectral efficiency (SE) as measured in bit per second per Hertz is one important parameter used to characterize a wireless system for comparison between different systems or between different configurations of the same system. This work provides a holistic approach of cross‐layer optimizations with the intent of maximizing SE by combining AMC and HARQ. It formulates closed‐form equations for calculating the average SE for wireless systems with the Rayleigh fading channel model. A new online algorithm is developed to optimize SE for both Rayleigh and non‐Rayleigh fading channel. Simulations using proven LTE model are performed to compare SE obtained from closed‐form equations and the developed algorithm for different system configurations. With the developed algorithm to determine how many retransmissions required in addition to the initial transmission in advance depending on the current wireless channel condition, the latency can be reduced up to 24 ms when sending the initial transmission and all of its retransmissions sooner than waiting for retransmission requests as is done previously. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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915.
We have studied water hyacinth (Eichhornia crassipes), a non-native nuisance plant found in the in San Francisco Bay Delta region, for its potential to phytoremediate mercury. Mercury is a common contaminant in San Francisco Bay Area waters because of gold mining activities. In this study, speciation of mercury in hyacinth roots and shoots, rates of mercury uptake by hyacinths in the laboratory, and mercury levels near the Big Break Region in the Delta were studied. In the speciation studies, Hg L3 edge X-ray absorption spectroscopic analysis of Hg model compounds and water hyacinth roots and shoots revealed that Hg was initially bound ionically to oxygen ligands in roots, most likely to carboxylate groups, and was bound covalently to sulfur groups in shoots. In laboratory uptake studies, we found that water hyacinths grown in 1 ppm Hg and one-quarter strength Hoagland's solution accumulated a maximum of 0.20 ppm in shoots and 16.0 ppm in roots, both reaching maximum concentrations after approximately 16 days. Mercury concentrations were found to be 0.26 +/- 0.20 ppm in the water and 0.86 +/- 1.70 ppm in sediment at Big Break. It was proposed that water hyacinths have the potential to phytoremediate mercury in the water at Big Break if the current herbicide treatments are replaced by physical removal. 相似文献
916.
Ha Tran Nguyen Olivier Coulembier Julien De Winter Pascal Gerbaux Xavier Crispin Philippe Dubois 《Polymer Bulletin》2011,66(1):51-64
Regioregular poly(3-hexylthiophene) has been successfully incorporated into various poly(N,N-dimethylamino-2-ethyl methacrylate)-based block copolymers, i.e., P3HT-b-PDMAEMA, via Grignard metathesis (GRIM) method and atom transfer radical polymerization (ATRP) reactions. The structure of
the diblock copolymers was fully confirmed by FT-IR, 1H NMR spectroscopy, gel permeation chromatography (GPC), and ultraviolet–visible spectroscopy (UV–vis). The recovered copolymers
could be treated by protonation of the pending tertiary amine functions and depending on the relative content in PDMAEMA,
the copolymers could be solubilized in more polar solvents where P3HT alone proved to be totally insoluble. 相似文献
917.
采用热压烧结法制备了原位复合(TiB2+TiC)/Ti3SiC2复相陶瓷。采用X射线衍射、扫描电镜和透射电镜对材料的物相组成和显微结构进行了表征,研究了烧结温度对材料物相组成、烧结性能、显微结构与力学性能的影响。结果表明:烧结温度在1 350~1 500℃范围内,随着烧结温度的升高,合成反应进行逐渐完全,材料的密度、抗弯强度和断裂韧性显著提高。1 500℃烧结可得到致密的原位复合(TiB2+TiC)/Ti3SiC2复相陶瓷,材料晶粒发育较完善,层片状Ti3SiC2、柱状TiB2与等轴状TiC晶粒清晰可见,增强相晶粒细小,晶界干净,材料的抗弯强度、断裂韧性和Vickers硬度分别达到741 MPa,10.12 MPa.m1/2和9.65 GPa。烧结温度达到1 550℃时Ti3SiC2开始发生分解,材料的密度和力学性能又显著下降。 相似文献
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919.
稀土/臭氧联合处理印染废水的研究 总被引:2,自引:0,他引:2
利用稀土/臭氧对模拟印染废水进行了降解实验。结果表明,稀土与臭氧氧化降解的协同作用和稀土投加量、温度、反应时间及pH有着很大关系。在本实验条件下,稀土和臭氧联用提高了臭氧的氧化率,取得了较为满意的实验效果。 相似文献
920.
The effects of temperature and magnetic field on aragonite and calcite growth were investigated in a stirred-tank crystallizer, using the constant-composition technique. At room temperature without magnetization, the calcite seeds grew but the aragonite did not. When the growth rates of the aragonite and calcite seeds were measured in the presence of a magnetic field at temperatures above room temperature, the synergetic effects were significant but with differing effects on the different seeds. The cluster-transformation mechanism was used to explain the growth rate data. Finally, the aragonite growth rate data were compared with data obtained in a fluidized bed. 相似文献