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71.
72.
Francesca Frati Keith Chamberlain Michael Birkett Samuel Dufour Patrick Mayon Christine Woodcock Lester Wadhams John Pickett Gianandrea Salerno Eric Conti Ferdinando Bin 《Journal of chemical ecology》2009,35(2):201-208
The profiles of volatile chemicals emitted by Vicia faba plants damaged by Lygus rugulipennis feeding, and by feeding plus oviposition, were shown to be quantitatively different from those released by undamaged plants.
Samples of volatile chemicals collected from healthy plants, plants damaged by males as a consequence of feeding, plants damaged
by females as a consequence of feeding and oviposition, plants damaged by feeding with mated males still present, and plants
damaged by feeding and oviposition with gravid females still present, showed significant differences in the emission of hexyl
acetate, (Z)-β-ocimene, (E)-β-ocimene, (E)-β-caryophyllene, and methyl salicylate. In particular, treatments with mated females present on plants had a significant
increase in emission levels of the above compounds, possibly due to eggs laid within plant tissues or active feeding, compared
with undamaged plants and plants damaged by males feeding, with or without insects still present. Furthermore, the pheromonal
blend released by mated L. rugulipennis females, mainly comprising hexyl butyrate, (E)-2-hexenyl butyrate, and (E)-4-oxo-2-hexenal, was enhanced when females were active on broad bean plants, whereas such an increase was not observed in
males. Both sexes gave electroantennogram responses to green leaf volatiles from undamaged plants and to methyl salicylate
and (E)-β-caryophyllene emitted by Lygus-damaged plants, suggesting that these compounds may be involved in colonization of host plants by L. rugulipennis. In addition, mated males and females were responsive to hexyl butyrate, (E)-2-hexenyl butyrate, and (E)-4-oxo-2-hexenal released by mated females on V. faba, indicating that these substances could have a dual function as a possible aggregation pheromone in female–female communication,
and as a sex pheromone in female–male communication.
An erratum to this article can be found at 相似文献
73.
Rhenium-nickel alloys were deposited on copper substrates in a small three-electrode cell, under galvanostatic conditions. The bath solution consisted of ammonium perrhenate, citric acid and nickel sulfamate. The effects of bath composition and deposition time were studied. The Faradaic efficiency (FE) and partial deposition current densities were calculated based on mass gain and elemental analysis using energy dispersive spectroscopy. The surface morphology was characterized by scanning electron microscopy. The thickness of the coating was measured on metallographic cross-sections. The results are discussed with emphasis on routes to increase the Faradaic efficiency and rhenium content in the coating. A plausible mechanism for the electrodeposition of rhenium-nickel alloys is presented. 相似文献
74.
H. Ben youcef S. Alkan Gürsel A. Buisson L. Gubler A. Wokaun G. G. Scherer 《Fuel Cells》2010,10(3):401-410
The mechanical stability is, in addition to thermal and chemical stability, a primary requirement of polymer electrolyte membranes in fuel cells. In this study, the impact of grafting parameters and preparation steps on stress–strain properties of ETFE‐based proton conducting membranes, prepared by radiation‐induced grafting and subsequent sulphonation, was studied. No significant change in the mechanical properties of the ETFE base film was observed below an irradiation dose of 50 kGy. It was shown that the elongation at break decreases with increasing both the crosslinker concentration and graft level (GL). However, the tensile strength was positively affected by the crosslinker concentration. Yield strength and modulus of elasticity are almost unaffected by the introduction of crosslinker. Interestingly, yield strength and modulus of elasticity increase gradually with GL without noticeable change of the inherent crystallinity of grafted films. The most brittle membranes are obtained via the combination of high GL and crosslinker concentration. The optimised ETFE‐based membrane (GL of ∼25%, 5% DVB v/v), shows mechanical properties superior to those of Nafion® 112 membrane. The obtained results were correlated qualitatively to the other ex situ properties, including crystallinity, thermal properties and water uptake of the grafted membranes. 相似文献
75.
Kaplan I Halitschke R Kessler A Sardanelli S Denno RF 《Journal of chemical ecology》2008,34(10):1349-1359
Herbivores induce systemic changes in plant traits, and the strength of these induced responses is often associated with the
degree of vascular connectivity that links damaged and undamaged plant tissues. Although this phenomenon is known to occur
aboveground in leaves, it is unknown whether or not leaf–root induction similarly follows the vascular architecture of plants.
To test for this possibility, we manipulated foliar and root herbivory on tobacco (Nicotiana tabacum) by the leaf-chewing insect Spodoptera exigua and the root-galling nematode Meloidogyne incognita. Subsequent changes in secondary chemistry (alkaloids and phenolics) were measured in leaves and roots that were orthostichous
(vertically aligned) and nonorthostichous (opposite) from the herbivore-damaged tissues. Aboveground caterpillar herbivory
elicited stronger secondary chemical responses in orthostichous compared with nonorthostichous plant tissues, although the
magnitude of this difference was greater in leaves than roots. However, belowground nematode herbivory did not affect the
secondary chemistry of tobacco leaves, despite inducing strong local responses in roots. Thus, plant vascular architecture
can mediate the magnitude of systemic induction in roots as well as in leaves, with stronger responses in tissues that are
more closely aligned. As a result, herbivores that co-occur on the same sector of plant (both aboveground and belowground)
may be more likely to affect one another via induced responses than herbivores that occur on plant tissues sharing fewer resources.
Miscellaneous Robert F. Denno, deceased 相似文献
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78.
为保证复杂探井的顺利钻进,更好地保护油气层,在钻前进行地层3项压力(地层孔隙压力、坍塌压力和破裂压力)剖面的预测非常重要.利用邻井测井资料、钻井工程资料对大港油田南大港潜山构造带歧南9X1、歧南9X2等井,在钻前进行了地层3项压力预测.根据该地区进入油气层段前地层坍塌压力较高,而进入油气层后地层坍塌压力下降,同时油层孔隙压力较低的实际情况,采用了一套与传统井身结构设计完全不同的设计方式,虽然增加了一定的套管成本,却保证了钻井施工的顺利进行,有效保护了油气层,与邻井相比,产量大幅度提高. 相似文献
79.
羌塘盆地雀莫错沉降-堆积中心成因:热力衰减塌陷沉降 总被引:8,自引:0,他引:8
在羌塘盆地东北部雀莫错地区侏罗系厚度巨大、层序齐全。其中,侏罗纪最早沉积的雀莫错组和最晚沉积的雪山组,现今地层残存厚度均超过1300m,分别属盆地内同期显著的局部沉降-堆积中心。这两期沉降-堆积中心的发育背景和演化过程颇为相似,即前期均有热力-岩浆活动的证据和与之有关的隆起背景;随后,早期沉积较薄甚至遭受剥蚀的隆起区发生快速沉降,接受巨厚沉积。这种隆、坳特征在时间上前后相随、上下叠置的特别现象,为热力作用形成的构造所特有。这一特征是雀莫错地区经历了(1)早期深部热力-岩浆作用上拱、岩浆喷溢,地壳表浅层隆升剥蚀,和(2)晚期深部热力衰减冷却,表浅层塌陷沉降之全过程的表现和记实。近年完成的航磁和大地电磁测深资料所反映出的深部结构方面证明此热力塌陷构造的存在。上侏罗统雪山组有机质镜质体反射率(R0)高达1.63%~1.83%,为中生代热异常的发生提供了证据。雪山期塌陷沉降型火山机构的热力衰减塌陷和伴随的岩浆活动,一直间断延续到晚白垩世-早第三纪初。随后,该区始发生抬升冷却。 相似文献
80.