全文获取类型
收费全文 | 844篇 |
免费 | 21篇 |
国内免费 | 1篇 |
专业分类
林业 | 88篇 |
农学 | 11篇 |
218篇 | |
综合类 | 33篇 |
农作物 | 35篇 |
水产渔业 | 87篇 |
畜牧兽医 | 345篇 |
园艺 | 4篇 |
植物保护 | 45篇 |
出版年
2023年 | 3篇 |
2022年 | 16篇 |
2021年 | 28篇 |
2020年 | 15篇 |
2019年 | 20篇 |
2018年 | 13篇 |
2017年 | 21篇 |
2016年 | 22篇 |
2015年 | 32篇 |
2014年 | 29篇 |
2013年 | 93篇 |
2012年 | 43篇 |
2011年 | 51篇 |
2010年 | 22篇 |
2009年 | 45篇 |
2008年 | 56篇 |
2007年 | 50篇 |
2006年 | 62篇 |
2005年 | 62篇 |
2004年 | 49篇 |
2003年 | 42篇 |
2002年 | 41篇 |
2001年 | 16篇 |
2000年 | 13篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1987年 | 1篇 |
1980年 | 1篇 |
1977年 | 2篇 |
排序方式: 共有866条查询结果,搜索用时 15 毫秒
851.
Hirako M 《Journal of agricultural and food chemistry》2008,56(15):6768-6774
The maternal-fetal and neonatal transfers of polychlorinated dibenzo- p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) were measured in the blood and milk of dams and in the blood of newborn and suckling calves. Calf blood toxic equivalent quantities (TEQs) were drastically increased by suckling. Blood concentrations of individual congeners were greater in suckling calves than in newborn calves, excluding octachlorodibenzo- p-dioxin (O 8CDD); O 8CDD did not readily transfer to milk but was readily absorbed by the gastrointestinal tract and remained in systemic circulation longer than other congeners. Congener concentrations in milk were correlated with maternal blood levels, and those in suckling calf blood were dependent on their concentrations in milk. These results suggest that neonatal calves absorb more lipophilic organochlorine compounds than prenatal fetuses, that those compounds that are transferred from dams to calves are associated not only with lipid transport but also with other carriers, and that the distribution of congeners is structure-dependent. 相似文献
852.
853.
Masato Kamisako Hiroyuki Sase Taeko Matsui Hiroko Suzuki Akiomi Takahashi Takuji Oida Makoto Nakata Tsumugu Totsuka Hiromasa Ueda 《Water, air, and soil pollution》2008,195(1-4):51-61
Fluxes of major ions in rainfall (RF), throughfall plus stemflow (TF + SF), and stream water (SW) were measured for five water years in a small catchment of a Japanese cedar forest near the Sea of Japan. The fluxes of most ions in RF and in TF + SF, including the non-sea-salt constituents, increased from late autumn to midwinter owing to the seasonal westerly wind. The concentrations of most ions in SW showed no obvious seasonal trend during the study period, whereas ${\text{NO}}_3 ^ - $ concentrations were lowest in summer, with a small seasonality. The Ca2+ and Mg2+ outputs in SW were approximately 3.7 and 1.8 times the TF + SF inputs of these cations, respectively. The large net outputs of base cations in the catchment may indicate a decrease in the soil's acid-neutralizing capacity. Annual dissolved inorganic nitrogen inputs in RF and in TF + SF were 17.7 and 17.9 kg N ha?1 year?1, respectively, which exceeded previously published thresholds in Europe and the U.S. (i.e., the values at which these inputs increased ${\text{NO}}_3 ^ - $ levels in SW) and equaled the highest level of nitrogen deposition previously reported in Japan. The ${\text{NO}}_{\text{3}} ^{\text{ - }} $ concentrations in SW were relatively high even in summer. During high-precipitation events, ${\text{NO}}_{\text{3}} ^{\text{ - }} $ concentrations in SW increased with increasing water discharge, and the pH decreased simultaneously during several events. Nitrogen deposition may contribute to the high ${\text{NO}}_{\text{3}} ^{\text{ - }} $ concentrations in SW and the temporary acidification that occurred during the rain events. 相似文献
854.
Effects of heterogeneity in stomatal behavior on gas-exchange characteristics of leaves from four tree species growing in different climates, including temperate, tropical monsoon and tropical rain forest, were investigated by combining gas-exchange measurements and the pressure-infiltration method. Field observations indicated linear relationships between whole-leaf conductance and the ratio of infiltrated to non-infiltrated leaf area (open stomata area) in Dipterocarpus sublamellatus Foxw. and Neobalanocarpus heimii (King) Ashton in a tropical rain forest in Peninsular Malaysia, whereas the ratio of infiltrated to non-infiltrated area rapidly increased up to the whole-leaf conductance at which the entire leaf was infiltrated in Cinnamomum camphora Sieb. in a temperate evergreen forest in Japan and in Azadirachta indica Juss. in a tropical monsoon area in Thailand. These results strongly suggest small ranges in bell-shaped stomatal conductance distributions in C. camphora and A. indica and bimodal stomatal conductance distributions in D. sublamellatus and N. heimii. The values of normalized maximum carboxylation rate at 25 degrees C (V(cmax25)) derived from gas-exchange measurements were not constant, but decreased with decreasing whole-leaf conductance in D. sublamellatus and N. heimii. A gas-exchange model analysis revealed a linear relationship between whole-leaf conductance and the ratio of infiltrated to non-infiltrated leaf area for bimodal stomatal conductance distributions, whereas for bell-shaped distributions, the relationships were nonlinear. Midday depression of apparent V(cmax25) in these species was mainly caused by bimodal stomatal closure. The bimodal stomatal distribution model could also explain diurnal changes in photosynthetic assimilation and transpiration rates in these species. 相似文献
855.
Determination of seven organosulfur compounds in garlic by high-performance liquid chromatography 总被引:2,自引:0,他引:2
Ichikawa M Ide N Yoshida J Yamaguchi H Ono K 《Journal of agricultural and food chemistry》2006,54(5):1535-1540
The properties of garlic (Allium sativum L.) are attributed to organosulfur compounds. Although these compounds change during cultivation and storage, there is no report of their simultaneous analysis. Here, a newly developed analytical method with a rapid and simple sample preparation to determine four sulfoxides and three gamma-glutamyl peptides in garlic is reported. All garlic samples were simply extracted with 90% methanol solution containing 0.01 N hydrochloric acid and prepared for analysis. Alliin, isoalliin, methiin, cycloalliin, and gamma-l-glutamyl-S-methyl-l-cysteine were determined by normal-phase HPLC using an aminopropyl-bonded column. gamma-l-Glutamyl-S-(2-propenyl)-l-cysteine and gamma-l-glutamyl-S-(trans-1-propenyl)-l-cysteine were separated on an octadecylsilane column. The overall recoveries were 97.1-102.3%, and the relative standard deviation values of intra- and interday precision were lower than 2.6 and 4.6%, respectively. This newly developed method offers some advantages over the currently accepted techniques including specificity, speed, and ease of use and would be useful for chemical and biological studies of garlic and its preparations. 相似文献
856.
Ito A Hattori M Yoshida T Watanabe A Sato R Takahashi K 《Journal of agricultural and food chemistry》2006,54(26):10191-10196
The binding of an amino acid, glycine (Gly), alanine (Ala), epsilon-aminocaproic acid (-AC), monosodium glutamate (GluNa), or lysine (Lys), to starch was examined by a biomolecular interaction analyzer (IAsys). A starch sample (ATS) hydrolyzed to an extent of 1% hydrolysis rate with 15% sulfuric acid was used as a model starch for the binding examination. The reducing end of ATS was oxidized by the Somogyi reagent, and the conversion of the reducing end to the carboxyl group of ATS was confirmed by a carboxylic acid fluorescence labeling reagent. The oxidized ATS was immobilized to the amino group of a sensor cuvette by using water-soluble carbodiimide and N-hydroxysuccinimide through an amide bond. The IAsys examination showed that Gly, Ala, and epsilon-AC scarcely bound to the immobilized starch chains but that GluNa and Lys favorably bound with their increasing concentrations. The relative binding index (RBI) of each amino acid was defined by the ratio of the slope of the linear regression equation between the binding response and the concentration for each amino acid to that for Gly. Because the relationships between the RBI and the pasting characteristics (pasting temperature, peak viscosity, breakdown, and swelling index) could each be expressed by a linear regression equation with a high correlation coefficient, it is concluded that the regulation of the pasting behavior of starch with an amino acid is caused by binding of the amino acid to the starch chains. 相似文献
857.
Demura H Kobayashi S Nemoto E Matsumoto N Furuya M Yukishita A Muranaka N Morita H Shirakawa K Maruya M Ohyama H Uo M Kubota T Hashimoto T Kawaguchi J Fujiwara A Saito J Sasaki S Miyamoto H Hirata N 《Science (New York, N.Y.)》2006,312(5778):1347-1349
The locations of the pole and rotation axis of asteroid 25143 Itokawa were derived from Asteroid Multiband Imaging Camera data on the Hayabusa spacecraft. The retrograde pole orientation had a right ascension of 90.53 degrees and a declination of -66.30 degrees (52000 equinox) or equivalently 128.5 degrees and -89.66 degrees in ecliptic coordinates with a 3.9 degrees margin of error. The surface area is 0.393 square kilometers, the volume is 0.018378 cubic kilometers with a 5% margin of error, and the three axis lengths are 535 meters by 294 meters by 209 meters. The global Itokawa revealed a boomerang-shaped appearance composed of two distinct parts with partly faceted regions and a constricted ring structure. 相似文献
858.
Effect of ensiling process of total mixed ration on fermentation profile,nutrient loss and in situ ruminal degradation characteristics of diet 下载免费PDF全文
This experiment aimed to determine the changes in chemical composition, fermentation profile, in situ disappearance characteristics, and nutrient losses of ensiled total mixed ration (TMR) containing steam‐flaked corn or brown rice (BR) during storage. TMRs for dairy cows, containing either steam‐flaked corn or BR at 31.9% with 15.2% rye silage, 40.5% alfalfa silage, 5.0% beet pulp and 7.0% soybean meal, were prepared (dry matter (DM) basis). Each TMR was placed in a plastic drum silo, stored at 23°C in an air‐conditioned room and sampled 0, 7, 14, 30, 90 and 210 days after preparation. In both grain sources, the fermentation products increased, while DM and starch storage losses increased and starch content greatly decreased during storage. The rapidly degradable fraction and effective ruminal degradability of DM, crude protein and starch increased during storage. These changes of dietary characteristics were large during 30 days of storage, but small after 90 days of storage. Replacing corn with BR led to increased fermentation products, starch loss and effective ruminal degradability of the ensiled TMR. These results indicate that the ensiling process of TMR changes the dietary characteristics and replacing corn with BR in TMR had a large impact on these dietary characteristics. 相似文献
859.
860.
Daigo Takemoto Yusuke Shibata Makoto Ojika Yuri Mizuno Sayaka Imano Mina Ohtsu Ikuo Sato Sotaro Chiba Kazuhito Kawakita Soriya Rin Maurizio Camagna 《Journal of General Plant Pathology》2018,84(5):312-320
The oomycete Phytophthora infestans is the causal agent of potato late blight, one of the most destructive and historically significant pathogens in agricultural production. A virus-induced gene silencing-based screening of the solanaceous model plant N. benthamiana resulted in revealing a wide range of resistance mechanisms of solanaceous plants against this pathogen. In this article, we present an overview of the various pathways involved in the N. benthamiana–P. infestans pathosystem, including some of the follow-up work that was triggered by these findings. The purpose of this review is to assemble these findings and integrate them into our current understanding of plant pathogen defense mechanisms and discuss their potential application for the development of potato resistance to P. infestans. 相似文献