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141.
F(2)-Isoprostanes (F(2)-IsoPs), regio- and stereoisomers of prostaglandin F(2alpha) (PGF(2alpha)), and urinary F(2)-IsoP metabolites including 2,3-dinor-5,6-dihydro-8-iso-PGF(2alpha) [2,3-dinor-8-iso-PGF(1alpha) (2,3-dinor-F1)] and 2,3 dinor-8-iso-PGF(2alpha) (2,3-dinor-F2), have all been used as biomarkers of oxidative stress. A novel method was developed to measure these biomarkers using a single solid phase extraction (SPE) cartridge, separation by HPLC, and detection by negative mode selected reaction monitoring (SRM) mass spectrometry (MS), using authentic standards of PGF(2alpha); 8-iso-PGF(2alpha); 2,3-dinor-F1 and 2,3-dinor-F2 to identify specific chromatographic peaks. The method was validated in a population of healthy, college-aged nonsmokers (n = 6 M/8F) and smokers (n = 6 M/5F). Urinary F(2)-IsoP concentrations were approximately 0.2-1.5 microg/g creatinine, 2,3-dinor-F1 was approximately1-3 microg/g and 2,3-dinor-F2 was approximately 3-5 microg/g. Additional F(2)-IsoPs metabolites were identified using SRM. The sum of all urinary F(2)-IsoP metabolites was 50-100 microg/g creatinine indicating their greater abundance than F(2)-IsoPs. Women had higher F(2)-IsoP metabolite concentrations than did men (MANOVA, main effect P = 0.003); cigarette smokers had higher concentrations than did nonsmokers (main effect P = 0.036). For men or women, respectively, smokers had higher metabolite concentrations than did nonsmokers (P < 0.05). Thus, our method simultaneously allows measurement of urinary F(2)-IsoPs and their metabolites for the determination of oxidative stress. 相似文献
142.
Fincher RM Dyer LA Dodson CD Richards JL Tobler MA Searcy J Mather JE Reid AJ Rolig JS Pidcock W 《Journal of chemical ecology》2008,34(4):558-574
Plants defend themselves against herbivores and pathogens with a suite of morphological, phenological, biochemical, and biotic
defenses, each of which is presumably costly. The best studied are allocation costs that involve trade-offs in investment
of resources to defense versus other plant functions. Decreases in growth or reproductive effort are the costs most often
associated with antiherbivore defenses, but trade-offs among different defenses may also occur within a single plant species.
We examined trade-offs among defenses in closely related tropical rain forest shrubs (Piper cenocladum, P. imperiale, and P. melanocladum) that possess different combinations of three types of defense: ant mutualists, secondary compounds, and leaf toughness.
We also examined the effectiveness of different defenses and suites of defenses against the most abundant generalist and specialist
Piper herbivores. For all species examined, leaf toughness was the most effective defense, with the toughest species, P. melanocladum, receiving the lowest incidence of total herbivory, and the least tough species, P. imperiale, receiving the highest incidence. Although variation in toughness within each species was substantial, there were no intraspecific
relationships between toughness and herbivory. In other Piper studies, chemical and biotic defenses had strong intraspecific negative correlations with herbivory. A wide variety of defensive
mechanisms was quantified in the three Piper species studied, ranging from low concentrations of chemical defenses in P. imperiale to a complex suite of defenses in P. cenocladum that includes ant mutualists, secondary metabolites, and moderate toughness. Ecological costs were evident for the array
of defensive mechanisms within these Piper species, and the differences in defensive strategies among species may represent evolutionary trade-offs between costly defenses. 相似文献
143.
Demonstration of starter unit interprotein transfer from a Fatty Acid synthase to a multidomain, nonreducing polyketide synthase 总被引:1,自引:0,他引:1
J Foulke-Abel CA Townsend 《Chembiochem : a European journal of chemical biology》2012,13(13):1880-1884
The pathway for substrate transacylation between a fungal type I fatty acid synthase (FAS) and a nonreducing polyketide synthase (NR-PKS) was determined by in vitro reconstitution of dissected domains. System kinetics were influenced by domain dissections, and the FAS phosphopantetheinyl transferase (PPT) monodomain exhibited coenzyme A selectivity for the post-translational activation of the FAS acyl carrier protein (ACP). 相似文献
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146.
吸汗速干服装是人们着装的客观要求。本文论述了服装舒适性的基本原理,并重点介绍了Coolplus纤维及纯棉针织物吸汗速干产品的开发与实际应用。 相似文献
147.
为探究红茶代谢产物的产地差异,本实验采用感官审评方法及超高效液相色谱串联质谱(UPLC-MS/MS)的广泛靶向代谢组测定方法,对福建省福安市和尤溪县产红茶中的代谢产物进行比较分析。结果表明:福安红茶以“醇和”的滋味特征为主,尤溪红茶以“甘醇”的滋味特征为主。利用代谢组学方法在两地的红茶中鉴定出黄酮、酚酸类、脂质、有机酸、氨基酸及其衍生物等共937种代谢物,通过主成分分析(PCA)和正交偏最小二乘判别分析(OPLS-DA)可以显著区分不同产地红茶,并鉴定出410种具有显著差异的代谢物。尤溪红茶中有291种差异代谢物的相对含量高于福安红茶,其中紫云英苷、表儿茶素(EC)、L-谷氨酰胺、L-天冬氨酸、L-赖氨酸、L-色氨酸、L-谷氨酸、绿原酸、苯乙胺和牡荆素-2'-O-鼠李糖苷等差异代谢产物对于两地红茶的不同滋味品质形成可能具有重要贡献。代谢通路分析发现,两地红茶的氨基酸和黄酮类物质代谢水平具有显著差异,可能是形成两地红茶滋味品质差异的原因。研究为茶叶产地鉴别提供理论依据。 相似文献
148.
149.
高性能运动及户外服装织物性能研究 总被引:2,自引:0,他引:2
本文论述了高性能运动及户外服装用纤维的湿传递机理及信影响因素,并介绍了防水透气织物及吸湿速干纤维、织物的类别及原理。 相似文献
150.