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   417篇
  免费   23篇
  国内免费   1篇
林业   16篇
农学   24篇
  62篇
综合类   24篇
农作物   90篇
水产渔业   41篇
畜牧兽医   143篇
园艺   8篇
植物保护   33篇
  2022年   12篇
  2021年   15篇
  2020年   16篇
  2019年   11篇
  2018年   10篇
  2017年   22篇
  2016年   26篇
  2015年   30篇
  2014年   20篇
  2013年   23篇
  2012年   23篇
  2011年   39篇
  2010年   23篇
  2009年   22篇
  2008年   32篇
  2007年   23篇
  2006年   21篇
  2005年   18篇
  2004年   22篇
  2003年   10篇
  2002年   9篇
  2001年   3篇
  2000年   4篇
  1999年   3篇
  1997年   2篇
  1996年   1篇
  1933年   1篇
排序方式: 共有441条查询结果,搜索用时 15 毫秒
91.
A competitive indirect enzyme-linked immunosorbent assay was developed for the fungicide iprovalicarb, using a polyclonal antibody produced against a hapten conjugated through the carboxyl group on the benzene ring to keyhole limpet hemocyanin. Under an optimized condition using a heterologous format, an IC(50) of 3.51 ng/mL and the lowest detection limit of 0.065 ng/mL were obtained. When the isopropoxy group was removed from the iprovalicarb structure for the synthesis of a hapten, the resulting hapten was not successful as an immunogen, indicating that the isopropyl moiety was an important epitope, as evidenced by the cross-reactivities of some structurally related compounds. When applied to the real crop and water samples, the recoveries were in the range of 80.52-144.70% (n = 4) and 72.11-100.43% (n = 4), respectively. Accordingly, this ELISA can be used as a useful method for monitoring iprovalicarb residues in crop and water samples.  相似文献   
92.
The high incidence of cardiovascular disease and vitamin D deficiency in chronic kidney disease patients is well known. Vitamin D activation by omega-3 fatty acid (FA) supplementation may explain the cardioprotective effects exerted by omega-3 FA. We hypothesized that omega-3 FA and 25-hydroxyvitamin D (25(OH)D) supplementation may increase 1,25-dihydroxyvitamin D (1,25(OH)2D) levels compared to 25(OH)D supplementation alone in hemodialysis (HD) patients that have insufficient or deficient 25(OH)D levels. We enrolled patients that were treated for at least six months with 25(OH)D < 30 ng/mL (NCT01596842). Patients were randomized to treatment for 12 weeks with cholecalciferol supplemented with omega-3 FA or a placebo. Levels of 25(OH)D and 1,25(OH)2D were measured after 12 weeks. The erythrocyte membrane FA contents were also measured. Levels of 25(OH)D were increased in both groups at 12 weeks compared to baseline. The 1,25(OH)2D levels at 12 weeks compared to baseline showed a tendency to increase in the omega-3 FA group. The oleic acid and monounsaturated FA content decreased, while the omega-3 index increased in the omega-3 FA group. Omega-3 FA supplementation may be partly associated with vitamin D activation, although increased 25(OH)D levels caused by short-term cholecalciferol supplementation were not associated with vitamin D activation in HD patients.  相似文献   
93.
94.
Atopic dermatitis (AD) is a chronic inflammatory skin disease in which skin barrier dysfunction leads to dryness, pruritus, and erythematous lesions. AD is triggered by immune imbalance and oxidative stress. Echinochrome A (Ech A), a natural pigment isolated from sea urchins, exerts antioxidant and beneficial effects in various inflammatory disease models. In the present study, we tested whether Ech A treatment alleviated AD-like skin lesions. We examined the anti-inflammatory effect of Ech A on 2,4-dinitrochlorobenzene (DNCB)-induced AD-like lesions in an NC/Nga mouse model. AD-like skin symptoms were induced by treatment with 1% DNCB for 1 week and 0.4% DNCB for 5 weeks in NC/Nga mice. The results showed that Ech A alleviated AD clinical symptoms, such as edema, erythema, and dryness. Treatment with Ech A induced the recovery of epidermis skin lesions as observed histologically. Tewameter® and Corneometer® measurements indicated that Ech A treatment reduced transepidermal water loss and improved stratum corneum hydration, respectively. Ech A treatment also inhibited inflammatory-response-induced mast cell infiltration in AD-like skin lesions and suppressed the expression of proinflammatory cytokines, such as interferon-γ, interleukin-4, and interleukin-13. Collectively, these results suggest that Ech A may be beneficial for treating AD owing to its anti-inflammatory effects.  相似文献   
95.
ABSTRACT

This study investigated the effect of liquid fertilizer treatments on growth, flowering, leaf mineral content, and rhizome production during forcing of Curcuma alismatifolia ‘Chiang Mai Pink’ and C. thorelii ‘Chiang Mai Snow’. Plants were irrigated with 200 mL of 1.3 g L?1 of 15 nitrogen (N) -7 phosphorus (P) -14 potassium (K) water soluble fertilizer at 0, 1.3, 2.7, 4.0, 5.3, or 6.6 g L?1 weekly. Days to flower, flower stem length, and leaf length were recorded, the mineral contents in leaves were analyzed, and the number of rhizomes with tuberous roots were recorded at harvest. Flowering of the first inflorescence in both C. alismatifolia ‘Chiang Mai Pink’ and C. thorelii ‘Chiang Mai Snow’ was significantly delayed when plants received 6.6 g L?1 fertilizer as compared to the control plants. The number of rhizomes with more than 4 tuberous roots was highest when plants received 2.7 g L?1 fertilizer. No medium-sized rhizomes with more than seven tuberous roots were produced when ‘Chiang Mai Pink’ plants received 0, 4.0, 5.3, and 6.6 g L?1 fertilizer. Based on the production of rhizomes with four to six tuberous roots, optimum concentration of 15N -7P -14K water soluble fertilizer is 2.7 g L?1 for C. alismatifolia ‘Chiang Mai Pink’ and 1.3 to 4.0 g L?1 for C. thorelii ‘Chiang Mai Snow’. Although high boron content occurred only in the outer part of the second leaf when fertilizer concentrations were increased, leaf-margin burn (LMB) symptoms were not observed in both species and this could not be related to the production of rhizomes.  相似文献   
96.
An immunochromatography (ICG) strip test for rapid detection of atrazine in water samples was developed. A monoclonal antibody (MAb) specific to atrazine was produced from the cloned hybridoma cell (AT-1-M3) and used to develop a direct competitive enzyme-linked immunosorbent assay (DC-ELISA) and ICG strip. MAb conjugated to colloidal gold, and that was applied to the conjugate pad of the ICG strip. The visual detection limit for the ICG strip was 3 ng/mL. This test required only 10 min to get results and one step of sample to perform the assay. The results of water samples spiked with 5, 10, 20, and 50 ng/mL of atrazine by ICG strip were in good agreement with those obtained by DC-ELISA. The ICG strip was sufficiently sensitive and accurate to be useful for rapid screening of atrazine in various water samples.  相似文献   
97.
98.
Ribavirin (RBV) is a synthetic guanosine analog that is used as a drug against various viral diseases in humans. The in vitro antiviral effects of ribavirin against porcine viruses were demonstrated in several studies. The purposes of this study were to evaluate the adverse effects and pharmacokinetics of ribavirin following its intramuscular (IM) injection in pigs. Ribavirin was formulated as a double‐oil emulsion (RBV‐DOE) and gel (RBV‐Gel), which were injected into the pigs as single‐dose IM injections. After injection of RBV, all of the pigs were monitored. The collected serum and whole blood samples were analyzed by liquid chromatography–tandem mass spectrometry and complete blood count analysis, respectively. All of the ribavirin‐treated pigs showed significant decreases in body weight compared to the control groups. Severe clinical signs including dyspnea, anorexia, weakness, and depression were present in ribavirin‐treated pigs until 5 days postinjection (dpi). The ribavirin‐treated groups showed significant decrease in the number of red blood cells and hemoglobin concentration until 8 dpi. The mean half‐life of the RBV‐DOE and RBV‐Gel was 27.949 ± 2.783 h and 37.374 ± 3.502 h, respectively. The mean peak serum concentration (Cmax) and area under the serum concentration–time curve from time zero to infinity (AUCinf) of RBV‐DOE were 8340.000 ± 2562.577 ng/mL and 16 0095.430 ± 61 253.400 h·ng/mL, respectively. The Cmax and AUCinf of RBV‐Gel were 15 300.000 ± 3764.306 ng/mL and 207526.260 ± 63656.390 h·ng/mL, respectively. The results of this study provided the index of side effect and pharmacokinetics of ribavirin in pigs, which should be considered before clinical application.  相似文献   
99.
叶片表皮指纹在杜鹃花属分类中的意义   总被引:5,自引:0,他引:5  
本实验于2004年在东北林业大学进行。用指甲油印记法在光学显微镜下观察了杜鹃花属6个种(牛皮杜鹃 Rh.aureaum,兴安杜鹃Rh. dauricum, 照白杜鹃Rh. micranthum,迎红杜鹃Rh. mucronulatum,苞叶杜鹃 Rh. Redowskianum 和大字杜鹃Rh. schlippenbachii)的表皮指纹特征。对叶片的形态特征包括叶片下表皮气孔类型、保卫细胞和副卫细胞的特征、叶片两面的普通细胞(形状和垂周壁特征)和表皮毛进行了较详细的描述。所研究的6种杜鹃花中,有3种气孔类型,其中兴安杜鹃、照白杜鹃、和迎红杜鹃为单细胞型气孔(Pericytic 型),苞叶杜鹃为不规则型气孔(Anomocytic 型),牛皮杜鹃和大字杜鹃是平轴式气孔(Diacytic 式)。不同种间,单细胞型和平轴式气孔的副卫细胞类型在形状和表面特征上有所不同。普通表皮细胞的表面观为从四边形、六边形, 多边形或不规则型, 垂周壁呈平直或弯曲状。兴安杜鹃、照白杜鹃和迎红杜鹃3种的叶片两面均有腺鳞。所有这些叶片特点表明上述6种杜鹃花的表皮指纹具有种的特性。图4表2参29。  相似文献   
100.
We report the microstructures and electrical properties of poly(2-cyano-1,4-phenylene terephthalamide) (cyPPTA)-based composite films including pristine multi-walled carbon nanotube (MWCNT) of 0.3-10.0 wt%, which were manufactured by ultrasonication-based solution mixing and casting techniques. FT-IR spectra of the composite films revealed the existence of specific interaction between cyPPTA and MWCNT. Accordingly, the pristine MWCNTs were found to be dispersed uniformly in the cyPPTA matrix, as confirmed by TEM images. The electrical resistivity of the composite films decreased considerably from ~1010 Ω cm to ~100 Ω cm with the increase of the MWCNT content by forming a conductive percolation threshold at ~0.525 wt%. The composite films with 3.0-10.0 wt% MWCNT contents, which have sufficiently low electrical resistivity of ~102-100 Ω cm, exhibited excellent electric heating performance by attaining high maximum temperatures and electric power efficiency under given applied voltages of 10-100 V. Since the thermal decomposition of the composite films took place at 520-600 °C under air atmosphere, cyPPTA/MWCNT composite films could be used for high performance electric heating, antistatic, and EMI shielding materials.  相似文献   
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