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991.
992.
993.
Nanoaggregates such as nanowires, nanoparticles, nanotubules, and nanoribbons were prepared from bulk crystals, which are shaped as needles (1), blocks (2), tubules (3α), and plates (3β), respectively, by grinding and ultrasonication. Nanowires have diameters of approximately 2 nm, lengths of thousands of nanmeters, and the distance between adjacent nanowires is approximately 2 nm. The diameters of nanoparticles range from 3 to 5 nm. Nanotubules display diameters of 70 nm and lengths of thousands of nanometers, and nanoribbons exhibit widths of approximately 50 nm and lengths of hundreds of nanometers. All of the bulk crystals have been synthesized by the wet chemical method. Single-crystal X-ray diffraction reveals that crystal 1 is constituted by infinite one-dimensional {[NH(3)CH(2)CH(NH(2))CH(3)](C(6)H(4)O(2))[μ(2)-OC(6)H(4)O](Mo(VI)-O-Na-O)[NH(2)CH(2)CH(NH(2))CH(3)]}(n) (1), which acts as a parallel aligned quantum wire forming lamellas that assemble themselves into multilayered architecture. Crystal 2 consists of discrete [NH(3)CH(2)CH(NH(2))CH(3)](2)[Mo(VI)O(2)(O(2)C(6)H(4))(2)] (2), which presents as quantum particles and repeats itself along a three-dimensional crystal lattice. Crystal 3α, formed under 5 °C, and 3β, crystallized above 10 °C, are both composed of (NH(3)CH(2)CH(2)NH(2))(2)[Mo(VI)O(2)(O(2)C(6)H(4))(2)](NH(2)CH(2)CH(2)NH(2))(0.5) (3) but are packed in different ways. In crystal 3α, four [Mo(VI)O(2)(O(2)C(6)H(4))(2)](2-) circle into a quantum tube that is further assembled into multitubular architecture. However, in crystal 3β, two [Mo(VI)O(2)(O(2)C(6)H(4))(2)](2-) form a bilayered quantum lamellar motif that is piled into multilayered architecture. TEM reveals that all of the morphologies of the nanoaggregates are associated with the structures of the quantum motifs in their crystal lattices, which provide successful and effective access to assemble controlled nanostructures from quantum motifs of fine-desired and well-ordered bulk crystals. The technology of grinding and ultrasonication to prepare nanoaggregates is simple and available. 相似文献
994.
Yiyun Wang Ziyuan Li Yue Huang Changhua Tang Xiaoming Wu Jinyi Xu Hequan Yao 《Tetrahedron》2011,67(38):7406-7411
A mild copper(II)-catalyzed oxidation of 4-carboxythiazolines and 4-carboxyoxazolines to 4-carboxythiazoles and 4-carboxyoxazoles has been developed. Various substrates with alkyl or aryl substitutions at 2-position on azoline ring could be smoothly oxidized to the desired products in good to excellent yields. Moreover, the hydrolysis of the ester group could be avoided under this method. 相似文献
995.
996.
Recently, cities have become larger and larger, and more and more people are living in large cities. This phenomenon has caused serious traffic congestion which is very detrimental to the development of large cities. In this context, the subway has become the most effective solution for relieving traffic congestion and subways have been constructed in many cities, so the reliability and robustness of subways should be guaranteed. In this paper, Shanghai subway network, in China, will be analyzed and investigated; the topological characteristics and functional properties can be studied in order to assess the reliability and robustness. The topological characteristics can be measured using several parameters; meanwhile the fraction of removed nodes of Shanghai subway network is discussed and compared against that for a random network, and the critical threshold of this fraction is obtained. Two novel parameters called the functionality loss and connectivity of subway lines are proposed for measuring the transport functionality and the connectivity of subway lines. Subway lines 4 and 7 are selected as examples for evaluating the connectivity of lines subjected to different attack protocols. This study indicates that the subway network is robust against random attacks but fragile for malicious attacks, and the highest betweenness node-based attacks can cause the most serious damage to subway networks among the different attack protocols. 相似文献
997.
采用分布反馈式半导体激光器作为探测光源,结合程长为100 m的离散型多通吸收池,采用直接吸收光谱技术,对室温下中心波长2.33 μm附近各种低体积分数的CO及混合气体(CO,CHCH4和N2)的直接吸收光谱进行了测量。选择CO在4 288.289 8 cm-1位置的吸收谱线和CH4在4 287.650 15 cm-1处的吸收谱线进行痕量探测,在40 698 Pa的总压力下,实验测得CO的探测极限为8.15×10-6(信噪比约为216),CH4的探测极限为18.48×10-6(信噪比约为147)。 相似文献
998.
为了克服目前高能短脉冲装置压缩光栅的损伤阈值无法满足要求的问题,针对星光Ⅲ装置皮秒激光束的压缩器,设计了由熔石英材料构成的、具有较高损伤阈值的光子晶体光栅,该光栅由2维光子晶体和表面光栅结构两部分组成,具有高反射效率和强角色散的能力。计算结果显示:经过优化设计的光子晶体光栅在波长1 053 nm,57°~77°的入射范围内,-1级衍射效率超过了92%,而当入射角为71°时,在1 040~1 090 nm光谱范围内,-1级衍射效率超过92%,性能满足使用要求。 相似文献
999.
设计了一种以太阳能为驱动力,利用渗透压将水分从蒸发器端传输到冷凝器端的压差式吸附制冷机.水分先在蒸发器端被吸附板吸收,再通过渗透压自动运输到最后环节段,并被膨胀物质间歇式地挤压出吸水材料,进入冷凝器,从而保证水分不断从蒸发器抽出,产生制冷效果.通过改变太阳能制冷系统的四通换向阀的开启方向,实现吸附式制冷系统的连续制冷. 相似文献
1000.
高效液相色谱-串联质谱法测定猪肉中的阿维菌素类、地克珠利、妥曲珠利及其代谢物残留 总被引:2,自引:0,他引:2
建立了猪肉中阿维菌素、伊维菌素、多拉菌素、莫西菌素、乙酰氨基阿维菌素等5种阿维菌素类药物以及地克珠利、妥曲珠利、妥曲珠利砜、妥曲珠利亚砜等4种均三嗪类药物及其代谢物残留的高效液相色谱-串联质谱分析方法。样品采用乙腈提取,ODS粉分散固相萃取净化,经Venusil ASB C18色谱柱(150 mm×2.1 mm, 3.0 μm)分离,电喷雾串联四极杆质谱多反应离子监测方式测定。9种分析物在0.005~0.2 mg/L范围内线性关系良好,相关系数均大于0.990。猪肉基质中9种分析物在0.005、0.01、0.02 mg/kg加标水平下,回收率为73.2%~91.5%,相对标准偏差为12%~17%。该方法稳定、可靠,可满足猪肉中阿维菌素类、均三嗪类药物残留的检测与确证。 相似文献