首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2275篇
  免费   101篇
林业   64篇
农学   76篇
基础科学   3篇
  413篇
综合类   300篇
农作物   311篇
水产渔业   149篇
畜牧兽医   902篇
园艺   26篇
植物保护   132篇
  2022年   38篇
  2021年   49篇
  2020年   28篇
  2019年   27篇
  2018年   54篇
  2017年   50篇
  2016年   51篇
  2015年   47篇
  2014年   70篇
  2013年   104篇
  2012年   118篇
  2011年   154篇
  2010年   67篇
  2009年   63篇
  2008年   117篇
  2007年   127篇
  2006年   86篇
  2005年   97篇
  2004年   88篇
  2003年   90篇
  2002年   67篇
  2001年   43篇
  2000年   51篇
  1999年   43篇
  1997年   20篇
  1996年   13篇
  1995年   11篇
  1994年   15篇
  1992年   23篇
  1991年   33篇
  1990年   32篇
  1989年   27篇
  1988年   20篇
  1987年   31篇
  1986年   28篇
  1985年   27篇
  1984年   20篇
  1983年   19篇
  1979年   20篇
  1978年   12篇
  1977年   19篇
  1976年   11篇
  1974年   17篇
  1973年   25篇
  1972年   18篇
  1971年   14篇
  1970年   18篇
  1969年   20篇
  1968年   12篇
  1966年   11篇
排序方式: 共有2376条查询结果,搜索用时 46 毫秒
21.
22.
23.
CASE DESCRIPTION: 2 dogs were evaluated because of vomiting and lethargy (a Toy Poodle; dog 1) and acute respiratory distress, vomiting, and anorexia (a Chihuahua; dog 2). Dog 1 had been exposed to a commercial hydrocarbon waterproofing spray 24 hours before the development of clinical signs, and dog 2 was examined 18 hours after exposure to a waterproofing spray containing heptane, a highly flammable liquid hydrocarbon. CLINICAL FINDINGS: In both dogs, major gastrointestinal tract abnormalities were ruled out but respiratory status worsened. Thoracic radiography revealed a diffuse interstitial pulmonary pattern, and hypoxemia was detected. TREATMENT AND OUTCOME: Hospitalization for monitoring and care was required for both dogs. The dogs recovered with supportive care, which included administration of oxygen, fluids, and bronchodilators. Additionally, dog 1 received glucocorticoids via inhalation and supplemental enteral nutrition, whereas dog 2 was treated with an antimicrobial. CLINICAL RELEVANCE: The dogs of this report developed hydrocarbon pneumonitis following exposure to waterproofing sprays. Such sprays contain potentially toxic hydrocarbons. The severity of the adverse effects associated with exposure may have been amplified because the dogs were physically small and were exposed to a relatively large amount of aerosolized spray within small areas. Development of chemical pneumonitis in pet animals is best prevented by application of waterproofing sprays in well-ventilated or outdoor areas from which pets have been excluded. With prolonged hospitalization and considerable monitoring and care, affected dogs can recover from these exposures.  相似文献   
24.
A novel technique was developed to estimate the caudal medial tibial plateau landmark in the face of osteophytosis to improve accuracy in tibial plateau angle measurements. Using this technique, tibial plateau angles were evaluated in 31 normal dogs before and 8 months after right cranial cruciate ligament transection. There was no significant difference in mean tibial plateau angle before or after induction of osteophytosis. Additionally, it was determined that 90% of dogs had a difference of =2 degrees between right and left tibial plateau angles, which was considered symmetrical.  相似文献   
25.
26.
27.
Sargassum horneri (S. horneri), an edible brown alga, has been proposed as a functional food with an improvement effect on abnormal skin immune responses. The present study investigates the anti-allergic effect of an ethanol extract from S. horneri (SHE) on immunoglobulin E (IgE)/bovine serum albumin (BSA)-mediated activation in bone marrow-derived cultured-mast cells (BMCMCs) and passive cutaneous anaphylaxis (PCA) reaction in mice. SHE markedly and dose-dependently suppressed the degranulation of BMCMCs by reducing the β-hexosaminidase and histamine release without cytotoxicity. In addition, SHE significantly decreased the FcεRI expression on the surface of BMCMCs and its IgE binding. Moreover, SHE reduced the mRNA expression and the production of allergic cytokines; interleukin (IL)-1β, IL-4, IL-5, IL-6, IL-10, IL-13; interferon (IFN)-γ and/or tumor necrosis factor (TNF)-α; and a chemokine, thymus and activation-regulated chemokine (TARC), by suppressing the activation of Src-family kinases and nuclear factor (NF)-κB signaling. In further study, the application of SHE reduced the PCA reaction in an IgE/BSA-induced type I allergic mice model. Taken together, we suggest that SHE has an anti-allergic effect in type I allergic responses.  相似文献   
28.
Analysis of the chemical components from the culture broth of the marine bacterium Saccharomonospora sp. CNQ-490 has yielded three novel compounds: saccharobisindole (1), neoasterric methyl ester (2), and 7-chloro-4(1H)-quinolone (3), in addition to acremonidine E (4), pinselin (5), penicitrinon A (6), and penicitrinon E (7). The chemical structures of the three novel compounds were elucidated by the interpretation of 1D, 2D nuclear magnetic resonance (NMR), and high-resolution mass spectrometry (HRMS) data. Compound 2 generated weak inhibition activity against Bacillus subtilis KCTC2441 and Staphylococcus aureus KCTC1927 at concentrations of 32 μg/mL and 64 μg/mL, respectively, whereas compounds 1 and 3 did not have any observable effects. In addition, compound 2 displayed weak anti-quorum sensing (QS) effects against S. aureus KCTC1927 and Micrococcus luteus SCO560.  相似文献   
29.
Landings in the blue crab, Portunus trituberculatus, fishery in Korean waters of the Yellow Sea have declined substantially from 11,000 t in the 1980s to 2,300 t in 2004. Blue crab habitat quality in the Yellow Sea has been degraded by anthropogenic activities including sand mining, land reclamation, and coastal pollution. Various traditional management measures have been implemented, including closed seasons during spawning and size limits, but these measures alone have been unsuccessful to conserve blue crab stocks. Consequently, a total allowable catch and a stock-rebuilding program using an ecosystem-based management approach were implemented in 2003 and 2006, respectively to rebuild blue crab stocks and restore habitats. This program involved assessment of both blue crab stock status and trammel-net fishery impacts at an ecosystem-level using an ecosystem-based fisheries assessment method ( [Zhang et al., 2009] and [Zhang et al., 2010]), which considered fishery data from catch and effort time-series, crab population biology, and ecosystem characteristics, including habitats and environmental conditions. Recent (2008) management status indices have shown significant positive change compared to conditions in 2000 with respect to sustainability of the stock and fishery and with regards to biodiversity and ecosystem habitat quality.  相似文献   
30.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号