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921.
LIU JiaHong XU He QIN DaYong WANG Hao WANG JianHua LI HaiHong BAO ShuJun 《科学通报(英文版)》2013,58(27):3312-3319
The water shortage problem in the Haihe River Basin is the most severe in China, and has restricted its economic development. Over-extraction of groundwater has been very severe in the past 30 years. To solve this problem, scientific decisions should be made from a historical perspective. It is important to describe water cycle evolution in the Haihe River basin over the past 10000 years. Datasets of paleoclimate, paleogeography, palynoflora, historical record, isotopic abundance ratio and content were collected for research on different time scales. Some interesting conclusions were drawn by a comprehensive analysis method. First, radiation was the intrinsic force driving the evolution of water cycle. Generally, precipitation increased with temperature. Second, precipitation was high during 8 ka-5 ka B.P., the so-called Yangshao warm period of the Middle Holocene, which recharged the major part of the Quaternary groundwater. Third, heavy floods during this period transported sediment to the seaside, forming the Coastal Plain where cities such as Tianjin, Huanghua, Cangzhou are now located. In the last 3000 years, intermittent moderate floods did not have enough energy to transport sediment to the sea. Rivers usually overflowed in the piedmont region of the Taihang Mountains, and sediment deposited there formed the Piedmont Plain, where locate Shijiazhuang, Xingtai, Handan, Baoding and other cities. Precipitation had a high correlation with temperature in Haihe River Basin in the past 10000 years: the high temperature usually coupled with high precipitation. Today precipitation in the Haihe River Basin is relatively low, owing to low temperature. This study reveals the relationship between temperature, precipitation and river networks in the past 10000 years in Haihe River Basin, which has great scientific and practical importance in understanding the current water circulation and water shortage. 相似文献
922.
Sample maturation calculated using Raman spectroscopic parameters for solid organics: Methodology and geological applications 总被引:3,自引:0,他引:3
LIU DeHan XIAO XianMing TIAN Hui MIN YuShun ZHOU Qin CHENG Peng SHEN JiaGui 《科学通报(英文版)》2013,58(11):1285-1298
The shape and shift of Raman peak of solid organics prove to be capable of revealing atomic and molecular level vibration information of aromatic ring structure and its relationship with sample maturation. Raman "D" peaks and "G" peaks of a series of continuously maturated coal samples were measured, and the inter-peak intervals (G-D) and peak height ratios (Dh/Gh) were derived and correlated with the vitrinite reflectance (vRo%) of standard coal samples. As a result, two formulae were established by using the two Raman indices for calculation of Raman reflectance (RmcRo%), which is equivalent to vitrinite reflectance. The formula for calculating Raman reflectance indicative of organic maturation using Raman shift inter-peak interval (G-D) is RmcRo%=0.0537d(G-D)-11.21, which is mainly applicable to matured to highly matured carbonized samples of solid organics; The formula for calculating Raman reflectance indicative of organic maturation using Raman peak height ratio (Dh/Gh) is RmcRo%=1.1659h (Dh/Gh)+2.7588, which is mainly applicable to carbonized samples of solid organics that are over matured or going to be turned into granulated graphite. Preliminary applications indicate that Raman reflectance "RmcRo%" calculated based on results of Raman spectral analysis of solid organics can be used to characterize sample maturation at molecular level, so enjoying extensive prospects in geological applications. 相似文献
923.
A new type of dendritic polymer, named dendronized hyperbranched polymer (DHP), was prepared successfully by the macro-monomer approach. Thanks to the perfect 3D isolation effects, DHPG1 exhibited good NLO property with d 33 value of 133 pm/V, higher than its analogues of dendronized polymer and dendrimer, and its stability of NLO effect was also enhanced. 相似文献
924.
A gneissic granite with an U-Pb age of 313±4 Ma was found in northeastern Fujian Province,South China.It is an S-type granite characterized by high K2O,Al2O3 and low SiO2,Na2O contents with high A/CNK ratio of 1.22 for the whole rock.Zircons with stubby morphology from the gneissic granite yield 206 Pb/238 U ages ranging from 326 to 301 Ma with a weighted average age of 313±4 Ma,and negative εHf(t) values from -8.35 to -1.74 with Hf model ages (TCDM) of 1.43 to 1.84 Ga.This S-type granite probably originated from late Paleoproterozoic crust in intracontinental orogeny.Integrated with previous results on paleogeographic reconstruction of South China,the nature of Paleozoic basins,Early Permian volcanism and U-Pb-Hf isotope of detrital zircons from the late Paleozoic to early Mesozoic sedimentary rocks,we suggest the occurrence of a late Paleozoic orogeny in the eastern Cathaysia Block,South China.This orogenic cycle includes Late Carboniferous (340-310 Ma) orogeny (compression) episode and Early Permian (287-270 Ma) post-orogenic or intraplate extension episode.Therefore,the late Paleozoic magmatism in the southeastern South China probably occurred during the intraplate orogeny rather than the arc-related process. 相似文献
925.
HE YuXin LIU WeiGuo ZHAO Cheng WANG Zheng WANG HuanYe LIU Yi QIN XianYan HU QiHou AN ZhiSheng LIU ZhongHui 《科学通报(英文版)》2013,58(9):1053-1059
Considerable efforts have been made to extend temperature records beyond the instrumental period through proxy reconstructions,in order to further understand the mechanisms of past climate variability.Yet,the global coverage of existing temperature records is still limited,especially for some key regions like the Tibetan Plateau and for earlier times including the Medieval Warm Period(MWP).Here we present decadally-resolved,alkenone-based,temperature records from two lakes on the northern Tibetan Plateau.Characterized by marked temperature variability,our records provide evidence that temperatures during the MWP were slightly higher than the modern period in this region.Further,our temperature reconstructions,within age uncertainty,can be well correlated with solar irradiance changes,suggesting a possible link between solar forcing and natural climate variability,at least on the northern Tibetan Plateau. 相似文献
926.
通过比较水提和碱提方格星虫粗多糖的抗菌和抗氧化活性,探讨这两种方法在方格星虫粗多糖提取中的优劣.结果,水提粗多糖对副溶血弧菌(Vib rio parahemol yticus)不敏感,对枯草芽孢杆菌(Bacillus subtilis)中度敏感,对其它细菌均为低敏感;碱提粗多糖对大肠杆菌(Escherichia coli)、金黄色葡萄球菌(Staphylococcus aures)和鳗弧菌(Vibrio an guillarum)低敏感,对白葡萄球菌(Staphylococcus cremoris)和副溶血弧菌中度敏感,对枯草芽孢杆菌和藤黄八叠球菌(Sarcina lutea)高度敏感.表明,碱提粗多糖的抗菌活性较水提粗多糖强.两种方法提取的方格星虫粗多糖均有一定的抗氧化性.水提和碱提多糖浓度均在800μg·mL-1时对羟自由基的清除能力最大,清除率分别为40.32%和39.86%;两种多糖浓度分别在800μg·mL-1和600μg· mL-1时对超氧自由基的抑制作用最大,抑制率分别为9.91%和5.86%.表明,水提方格星虫粗多糖的抗氧化性强于碱提粗多糖. 相似文献
927.
928.
建立了基于AR(1)-GARCH(1,1)的Gumbel Copula模型,并以此为基础刻画了中国房地产股市收益率与成交量之间的相关性.通过AIC信息准则进行拟合优度检验发现,Gumbel Copula函数模型能够更好地刻画收益率与成交量之间的相关结构,收益率与成交量之间存在上尾高的非对称相关,以及很弱的正相关的特征. 相似文献
929.
秦正龙 《徐州师范大学学报(自然科学版)》2013,(3):57-60
基于拓扑理论计算了16种酚类化合物的分子形状指数(mK)以及原子类型电性拓扑状态指数(En).应用多元线性回归及最佳变量子集方法,建立了这些拓扑指数与酚类化合物对硝化颗粒污泥活性抑制的定量结构-活性相关模型.该模型的传统判定系数R2为0.932,逐一剔除法的交叉验证系数R2cv为0.874,通过R2,F,R2Adj,R2cv,VIF,FIT等检验,证明该模型具有良好的稳健性和预测能力. 相似文献
930.