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排序方式: 共有160条查询结果,搜索用时 15 毫秒
91.
Abdo AA Ackermann M Atwood WB Baldini L Ballet J Barbiellini G Baring MG Bastieri D Baughman BM Bechtol K Bellazzini R Berenji B Blandford RD Bloom ED Bogaert G Bonamente E Borgland AW Bregeon J Brez A Brigida M Bruel P Burnett TH Caliandro GA Cameron RA Caraveo PA Carlson P Casandjian JM Cecchi C Charles E Chekhtman A Cheung CC Chiang J Ciprini S Claus R Cohen-Tanugi J Cominsky LR Conrad J Cutini S Davis DS Dermer CD de Angelis A de Palma F Digel SW Dormody M do Couto E Silva E Drell PS 《Science (New York, N.Y.)》2008,322(5905):1218-1221
Energetic young pulsars and expanding blast waves [supernova remnants (SNRs)] are the most visible remains after massive stars, ending their lives, explode in core-collapse supernovae. The Fermi Gamma-Ray Space Telescope has unveiled a radio quiet pulsar located near the center of the compact synchrotron nebula inside the supernova remnant CTA 1. The pulsar, discovered through its gamma-ray pulsations, has a period of 316.86 milliseconds and a period derivative of 3.614 x 10(-13) seconds per second. Its characteristic age of 10(4) years is comparable to that estimated for the SNR. We speculate that most unidentified Galactic gamma-ray sources associated with star-forming regions and SNRs are such young pulsars. 相似文献
92.
Ming-Mei Chang Chin C. Chiang Mark W. Martin Lee A. Hadwiger 《American Journal of Potato Research》1993,70(9):635-647
The coding sequence from the pea disease resistance response gene 49 (DRR49 gene), was transferred into the potato (Solanum tuberosum L.) cultivar Shepody viaAgrobacterium co-cultivation. Potato leaf explants were co-cultivated withAgrobacterium tumefaciens harboring a binary vector containing the coding sequence from the DRR49 gene under the control of the 35S promoter from cauliflower mosaic virus (CaMV). Transformed potato plants were selected by their resistance to kanamycin. The insertion of foreign DNAs was detected by polymerase chain reaction (PCR) and Southern blot analysis. The expression of DRR49 coding sequence was confirmed via the detection of the corresponding mRNA in northern blot analysis. Field pathogenicity tests indicated that transgenic plants expressing the pea DRR49 mRNA have higher tuber yields than the control plants when grown in PED (potato early dying) infested soil. 相似文献
93.
94.
Self-organizing radial basis neural network for predicting typhoon-induced losses to rice 总被引:1,自引:1,他引:0
The issue of the typhoon-induced economic losses to rice is investigated. In this study, we propose a hybrid self-organizing radial basis (SORB) neural network for estimating economic losses of rice for the whole Taiwan as well as three sub-regions. The data sets of 143 typhoon events from 1961 to 2008 were collected and analyzed. Data include rice losses and typhoon-related meteorological factors. A number of different input combinations of meteorological and temporal variables are implemented to select the optimal network for predicting the losses, and a two-stage clustering method is used to explore the spatial classification of 15 counties in Taiwan into three sub-regions. The simulation results indicate that the constructed SORB network has a great ability to capture the relationship between typhoon-related variables and rice losses. Furthermore, the SORB model also demonstrates its outstanding reliability and predictability for efficiently providing a valuable reference for counties in Taiwan that could protect farmers from exposure to increasing weather-related risk and accelerate the official decision making process on compensation for rice losses after the invasion of typhoons. 相似文献
95.
Li-Chung Hu Jui-Hsin Su Michael Yen-Nan Chiang Mei-Chin Lu Tsong-Long Hwang Yung-Husan Chen Wan-Ping Hu Nai-Cheng Lin Wei-Hsien Wang Lee-Shing Fang Yueh-Hsiung Kuo Ping-Jyun Sung 《Marine drugs》2013,11(6):1999-2012
Three new cembrane-type diterpenoids, flexibilins A–C (1–3), along with a known cembrane, (−)-sandensolide (4), were isolated from the soft coral, Sinularia flexibilis. The structures of cembranes 1–4 were elucidated by spectroscopic methods. The structure of 4, including its absolute stereochemistry, was further confirmed by single-crystal X-ray diffraction analysis. Cembrane 2 displayed a moderate inhibitory effect on the release of elastase by human neutrophils. 相似文献
96.
Chiang CJ Chern JT Wang JY Chao YP 《Journal of agricultural and food chemistry》2008,56(15):6348-6354
Optically pure amino acids have been widely used as intermediates in the synthesis of antibiotics, antifungal agents, pesticides, and sweeteners. Of particular importance, d- p-hydroxyphenylglycine (D-HPG) can be produced from d, l-hydroxyphenly hydantoin (D,L-HPH) in a two-step reaction mediated by d-hydantoinase and N-carbamoyl- d-amino acid amidohydrolase (or carbamoylase). To make this production more industrially appealing, the carbamoylase gene from Agrobacterium radiobacter NRRL B11291 cloned in an Escherichia coli strain was intensively mutated to improve the thermal stability of carbamoylase by three rounds of DNA shuffling. After an extensive screening of the mutant library, the mutant E. coli strain M303 was obtained to produce variant carbamoylase, CBL303, with three critical mutated residues, including V40A, G75S, and V237A. Further characterization showed that in comparison with the wild-type counterpart the evolved carbamoylase exhibited more than 20-fold tolerance to heat and, in addition, hydrogen peroxide as a result of the synergistic effect caused by the three mutations. Moreover, with the fusion of the chitin-binding domain (ChBD) of Chitinase A1, the evolved carbamoylase CBL303 was specifically adsorbed on chitin beads. Subsequent analysis indicated that the linkage between the enzyme and the affinity matrix was substantially stable. The half-life of the immobilized carbamolyase CBL303 could reach 210 h at 45 degrees C, whereas its free form had that of 17 h. In particular, when applied to D-HPG production, the immobilized enzyme could be recycled 16 times with the achievement of 100% conversion yield. Along with the previous illustration of d-hydantoinase immobilization, the success achieved by immobilization of the evolved carbamoylase in this work apparently offers a promising way for the efficient production of D-HPG from D,L-HPH. 相似文献
97.
98.
A.‐H. Liao C.‐B. Jiang C.‐C. Li H.‐C. Chuang J.‐S. Chiang Chiau W.‐T. Chan C.‐Y. Yeung M.‐L. Cheng H.‐C. Lee 《Journal of animal physiology and animal nutrition》2017,101(4):703-712
Chronic systemic lipopolysaccharide‐induced inflammation can cause obesity. In animal experiments, lactobacilli have been shown to inhibit obesity by modifying the gut microbiota, controlling inflammation and influencing the associated gene expression. A previous study found that high‐fat‐diet‐induced (HFD) obesity was suppressed by lactobacilli ingestion in rats via the inhibition of parasympathetic nerve activity. This study explored the combined use of lactobacilli ingestion and ultrasound (US) to control body weight and body fat deposition in HFD mice over an 8‐week experimental period. Male C57BL/6J mice received an HFD during treatment and were randomly divided into four groups: (i) control group (H), (ii) lactobacilli alone (HB), (iii) US alone (HU) and (iv) lactobacilli combined with US (HUB). The US was targeted at the inguinal portion of the epididymal fat pad on the right side. At the 8th week, body weight had decreased significantly in the HUB group (15.56 ± 1.18%, mean ± SD) group compared with the HU (26.63 ± 0.96%) and H (32.62 ± 5.03%) groups (p < 0.05). High‐resolution microcomputed tomography (micro‐CT) scans revealed that the reduction in total body fat volume was significantly greater in the HUB group (69%) than in the other two experimental groups (HB, 52%; HU, 37%; p < 0.05). The reductions in the thickness of the subcutaneous epididymal fat pads were significantly greater in the HUB group (final thickness: 340 ± 7 μm) than in the H (final thickness: 1150 ± 21 μm), HB (final thickness: 1060 ± 18 μm) and HU (final thickness: 370 ± 5 μm) groups (all p < 0.05). Combination therapy with lactobacilli and US appears to enhance the reduction in body weight, total and local body fat deposition, adipocyte size and plasma lipid levels over an 8‐week period over that achieved with lactobacilli or US alone in HFD mice. These results indicate that US treatment alone can reduce hyperlipidemia in HFD mice. 相似文献
99.
Chiang CL Chang YM Chang CT Sung HY 《Journal of agricultural and food chemistry》2005,53(19):7579-7585
A chitosanolytic enzyme was purified from a commercial ficin preparation by affinity chromatographic removal of cysteine protease on pHMB-Sepharose 4B and cystatin-Sepharose 4B and gel filtration on Superdex 75 HR. The purified enzyme exhibited both chitinase and chitosanase activities, as determined by SDS-PAGE and gel activity staining. The optimal pH for chitosan hydrolysis was 4.5, whereas the optimal temperature was 65 degrees C. The enzyme was thermostable, as it retained almost all of its activity after incubation at 70 degrees C for 30 min. A protein oxidizing agent, N-bromosuccinimide (0.25 mM), significantly inhibited the enzyme's activity. The molecular mass of the enzyme was 16.6 kDa, as estimated by gel filtration. The enzyme showed activity toward chitosan polymers exhibiting various degrees of deacetylation (22-94%), most effectively hydrolyzing chitosan polymers that were 52-70% deacetylated. The end products of the hydrolysis catalyzed by this enzyme were low molecular weight chitosan polymers and oligomers (11.2-0.7 kDa). 相似文献
100.
Huang CF Chen YW Yang CY Lin HY Way TD Chiang W Liu SH 《Journal of agricultural and food chemistry》2011,59(4):1087-1094
The effect of lotus leaf ( Nelumbo nucifera Gaertn.) on diabetes is unclear. We hypothesized that lotus leaf can regulate insulin secretion and blood glucose levels. The in vitro and in vivo effects of lotus leaf methanolic extract (NNE) on insulin secretion and hyperglycemia were investigated. NNE increased insulin secretion from β cells (HIT-T15) and human islets. NNE enhanced the intracellular calcium levels in β cells. NNE could also enhance phosphorylation of extracellular signal-regulated protein kinases (ERK)1/2 and protein kinase C (PKC), which could be reversed by a PKC inhibitor. The in vivo studies showed that NNE possesses the ability to regulate blood glucose levels in fasted normal mice and high-fat-diet-induced diabetic mice. Furthermore, the in vitro and in vivo effects of the active constituents of NNE, quercetin, and catechin, on glucose-induced insulin secretion and blood glucose regulation were evaluated. Quercetin did not affect insulin secretion, but catechin significantly and dose-dependently enhanced insulin secretion. Orally administered catechin significantly reversed the glucose intolerance in high-fat-diet-induced diabetic mice. These findings suggest that NNE and its active constituent catechin are useful in the control of hyperglycemia in non-insulin-dependent diabetes mellitus through their action as insulin secretagogues. 相似文献