全文获取类型
收费全文 | 13409篇 |
免费 | 860篇 |
国内免费 | 47篇 |
专业分类
林业 | 1154篇 |
农学 | 562篇 |
基础科学 | 130篇 |
3524篇 | |
综合类 | 469篇 |
农作物 | 739篇 |
水产渔业 | 1400篇 |
畜牧兽医 | 4967篇 |
园艺 | 259篇 |
植物保护 | 1112篇 |
出版年
2024年 | 21篇 |
2023年 | 98篇 |
2022年 | 183篇 |
2021年 | 327篇 |
2020年 | 307篇 |
2019年 | 308篇 |
2018年 | 557篇 |
2017年 | 573篇 |
2016年 | 574篇 |
2015年 | 451篇 |
2014年 | 557篇 |
2013年 | 842篇 |
2012年 | 980篇 |
2011年 | 982篇 |
2010年 | 579篇 |
2009年 | 519篇 |
2008年 | 793篇 |
2007年 | 784篇 |
2006年 | 643篇 |
2005年 | 574篇 |
2004年 | 544篇 |
2003年 | 499篇 |
2002年 | 388篇 |
2001年 | 304篇 |
2000年 | 311篇 |
1999年 | 261篇 |
1998年 | 67篇 |
1997年 | 69篇 |
1996年 | 57篇 |
1995年 | 57篇 |
1994年 | 34篇 |
1993年 | 32篇 |
1992年 | 77篇 |
1991年 | 58篇 |
1990年 | 57篇 |
1989年 | 66篇 |
1988年 | 52篇 |
1987年 | 54篇 |
1986年 | 52篇 |
1985年 | 63篇 |
1984年 | 43篇 |
1983年 | 46篇 |
1982年 | 28篇 |
1979年 | 48篇 |
1978年 | 42篇 |
1977年 | 31篇 |
1974年 | 32篇 |
1973年 | 55篇 |
1972年 | 37篇 |
1971年 | 31篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Detrital carbon accumulation accounts for most of an ecosystem's capacity to store organic carbon because the carbon contained as plant detritus exceeds that stored in living plants by about threefold. A comparative analysis of the mass and turnover of detrital carbon in ecosystems demonstrates that these properties are strongly related to the turnover rate of the dominant primary producers and are poorly related to ecosystem primary production. These results contribute to an understanding of the factors that control carbon storage in ecosystems and the role of carbon storage in the global carbon budget. 相似文献
72.
Snyder Marcía N. Schumaker Nathan H. Ebersole Joseph L. Dunham Jason B. Comeleo Randy L. Keefer Matthew L. Leinenbach Peter Brookes Allen Cope Ben Wu Jennifer Palmer John Keenan Druscilla 《Landscape Ecology》2019,34(5):1197-1197
Landscape Ecology - In the original publication of the article, the third author name has been misspelt. The correct name is given in this Correction. The original version of this article was revised. 相似文献
73.
Journal of Plant Diseases and Protection - Prior to the first occurrence of chestnut blight in 1976, leaf spot caused by Cylindrosporium castaneae was one of the most important diseases of European... 相似文献
74.
Ana E. González-Santiago Belinda Vargas-Guerrero Pedro M. García-López Alma L. Martínez-Ayala José A. Domínguez-Rosales Carmen M. Gurrola-Díaz 《Plant foods for human nutrition (Dordrecht, Netherlands)》2017,72(2):134-140
Lupinus albus seeds contain conglutin gamma (Cγ) protein, which exerts a hypoglycemic effect and positively modifies proteins involved in glucose homeostasis. Cγ could potentially be used to manage patients with impaired glucose metabolism, but there remains a need to evaluate its effects on hepatic glucose production. The present study aimed to analyze G6pc, Fbp1, and Pck1 gene expressions in two experimental animal models of impaired glucose metabolism. We also evaluated hepatic and renal tissue integrity following Cγ treatment. To generate an insulin resistance model, male Wistar rats were provided 30% sucrose solution ad libitum for 20 weeks. To generate a type 2 diabetes model (STZ), five-day-old rats were intraperitoneally injected with streptozotocin (150 mg/kg). Each animal model was randomized into three subgroups that received the following oral treatments daily for one week: 0.9% w/v NaCl (vehicle; IR-Ctrl and STZ-Ctrl); metformin 300 mg/kg (IR-Met and STZ-Met); and Cγ 150 mg/kg (IR-Cγ and STZ-Cγ). Biochemical parameters were assessed pre- and post-treatment using colorimetric or enzymatic methods. We also performed histological analysis of hepatic and renal tissue. G6pc, Fbp1, and Pck1 gene expressions were quantified using real-time PCR. No histological changes were observed in any group. Post-treatment G6pc gene expression was decreased in the IR-Cγ and STZ-Cγ groups. Post-treatment Fbp1 and Pck1 gene expressions were reduced in the IR-Cγ group but increased in STZ-Cγ animals. Overall, these findings suggest that Cγ is involved in reducing hepatic glucose production, mainly through G6pc inhibition in impaired glucose metabolism disorders. 相似文献
75.
R. Vilcacundo D. Barrio C. Carpio A. García-Ruiz J. Rúales B. Hernández-Ledesma W. Carrillo 《Plant foods for human nutrition (Dordrecht, Netherlands)》2017,72(3):294-300
Quinoa protein concentrate (QPC) was extracted and digested under in vitro gastrointestinal conditions. The protein content of QPC was in the range between 52.40 and 65.01% depending on the assay used. Quinoa proteins were almost completely hydrolyzed by pepsin at pH of 1.2, 2.0, and 3.2. At high pH, only partial hydrolysis was observed. During the duodenal phase, no intact proteins were visible, indicating their susceptibility to the in vitro simulated digestive conditions. Zebrafish larvae model was used to evaluate the in vivo ability of gastrointestinal digests to inhibit lipid peroxidation. Gastric digestion at pH 1.2 showed the highest lipid peroxidation inhibition percentage (75.15%). The lipid peroxidation activity increased after the duodenal phase. The digest obtained at the end of the digestive process showed an inhibition percentage of 82.10%, comparable to that showed when using BHT as positive control (87.13%). 相似文献
76.
Surface properties of fibrous and ground cotton and linen were investigated by inverse gas chromatography (IGC) and the contact angle with different liquids was also measured on fabrics composed of both fibers. Results proved that dispersion component of surface tension (γ s d ) determined by IGC depends not only on the surface energy, but also on several factors influencing the adsorbability of probe molecules on the cellulosic substrates. For cotton samples, the trapping of n-alkanes among waxy molecules in the outer layer of fibers can be presumed. This effect results in larger γ s d for cotton fibers than for linen in spite of the higher wettability of the linen fabrics. Besides the surface energy and trapping effects, the grinding also influences the γ s d values. Specific enthalpy of adsorption (ΔH A ab ) of polar probes could be determined on all linen samples, but only on the ground cotton sample. Lewis acid-base character calculated for linen and ground cotton samples depends on the same effects as the γ s d does. The similar ΔH A ab values of chloroform (acidic) and THF (basic) measured on each of the samples support the conclusion that the surface character is amphoteric, which is also proved by the high ΔH A ab values of the amphoteric ethyl acetate and acetone probes. 相似文献
77.
78.
New Forests - The coppice is a very flexible cultural system producing several calibers adapting to the demands of the market. Small-caliber roundwood from sweet chestnut (Castanea sativa Mill.)... 相似文献
79.
Robert Manuel L. Juárez-Gómez Juan Chaires-Pacheco Mariana Peña-Ramírez Yuri J. 《New Forests》2020,51(2):335-347
New Forests - Spanish red cedar, Cedrela odorata L. (Meliaceae), is a valuable timber tree in tropical American forests. Existing demand for elite individuals endangers the conservation of... 相似文献
80.
Morantes César Fernández Yarza Florencia Montes María L. Mercader Roberto C. Curutchet Gustavo Torres Sánchez Rosa M. 《Water, air, and soil pollution》2020,231(1):1-13
Water, Air, & Soil Pollution - The treatment efficiency of Chlorella sorokiniana and Scenedesmus species, immobilized in sodium alginate, was evaluated for removing nitrate from groundwater.... 相似文献