全文获取类型
收费全文 | 1219篇 |
免费 | 74篇 |
国内免费 | 10篇 |
专业分类
林业 | 78篇 |
农学 | 85篇 |
基础科学 | 29篇 |
453篇 | |
综合类 | 116篇 |
农作物 | 120篇 |
水产渔业 | 62篇 |
畜牧兽医 | 215篇 |
园艺 | 32篇 |
植物保护 | 113篇 |
出版年
2023年 | 19篇 |
2022年 | 57篇 |
2021年 | 78篇 |
2020年 | 75篇 |
2019年 | 97篇 |
2018年 | 125篇 |
2017年 | 112篇 |
2016年 | 86篇 |
2015年 | 44篇 |
2014年 | 53篇 |
2013年 | 140篇 |
2012年 | 67篇 |
2011年 | 75篇 |
2010年 | 49篇 |
2009年 | 32篇 |
2008年 | 41篇 |
2007年 | 34篇 |
2006年 | 30篇 |
2005年 | 15篇 |
2004年 | 7篇 |
2003年 | 8篇 |
2002年 | 8篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有1303条查询结果,搜索用时 15 毫秒
171.
M. Husain Khawaja G. Rasool Muhammad Tufail Abdullah M. A. Alhamdan Khalid Mehmood Abdulrahman S. Aldawood 《Journal of insect science (Online)》2015,15(1)
Comparative efficacy of three different modified atmospheres: 100% CO2, 75% CO2 + 25% N2, and 22 ppm ozone were examined against larval mortality of the almond moth, Ephestia cautella (Walker) (Lepidoptera: Pyralidae) at temperature regimes of 25°C and 35 ± 2°C and 60 ± 5% relative humidity, and 9:15 dark and light. Wandering young larval instars, which are fast growing, large enough in size and considered as more tolerant to modified atmosphere, were collected directly from the rearing culture, placed inside pitted date fruits of vars.: “Khudri,” “Ruziz,” and “Saqie,” were treated with aforementioned gases for 24, 48, and 72 h. The immediate and delayed larval mortality was recorded after each exposure timing. Ozone possessed the strongest fumigant toxicity causing 100% mortality with all varieties, at 25 and 35°C after 24 h exposure and was more effective than 75% CO2 that caused 83 and 100% immediate mortality with variety ruziz at 25 and 35°C, respectively. Extending the treatments exposure time to 72 h, 100% mortality was recorded by exposing larvae to any of the studied gases at 25 and 35°C. These results suggest that gases and temperature used in this study can be effectively used to control E. cautella in dates and stored grains. 相似文献
172.
Sajid Ali Marc Leconte Hidayatur Rahman Muhammad Shahab Saqib Pierre Gladieux Jérôme Enjalbert Claude de Vallavieille-Pope 《European journal of plant pathology / European Foundation for Plant Pathology》2014,140(2):275-290
Information on the pathogen virulence profile and diversity across locations is crucial for host germplasm improvement and deployment. The rapid acquisition of virulence to host resistance by the wheat yellow/stripe rust pathogen (Puccinia striiformis f.sp. tritici: PST), makes it crucial to know about its virulence and pathotype diversity. Recent studies have shown the plausible centre of origin of the pathogen in the Himalayan region, with Pakistan being the most ancestral to all other worldwide populations. To assess the status of virulence and pathotype diversity in the Himalayan region of Pakistan, a set of 127 PST infected wheat samples from eight locations were collected, multiplied and pathotyped using a set of 36 differential lines from the world set, European and Chinese sets, and 9 Avocet Yr isolines. Virulence (Vr) was recorded to 18 out of 24 tested yellow rust resistance (Yr) genes, while a total of 53 pathotypes were detected out of 127 isolates tested. Virulence was found to the resistance genes rarely deployed in Pakistan (Vr8) or even worldwide level (Vr5), while virulence to Vilmorin 23 (Yr3+) was absent in Pakistan, which is common in Europe. None of the pathotypes was dominant across all locations, however, no clear spatial structuring was observed for the studied locations. Our results suggested a high virulence and pathotype diversity in line with the previously proposed potential role of sexual recombination in the temporal maintenance of PST in the Himalayan region of Pakistan. This information should be useful in host resistance gene improvement and deployment. 相似文献
173.
Wheat is one of the most widely cultivated crops and, being the staple diet of more than 40 countries, it plays an imperative role in food security. Wheat has remarkable genetic potential to synchronize its flowering time with favourable environmental conditions. This ability to time its flowering is a key factor for its global adaptability and enables wheat plant to produce satisfactory grain yield under very diverse temperature and soil moisture conditions. Vernalization (Vrn), photoperiod (Ppd) and earliness per se (Eps) are the three genetic systems controlling flowering time in wheat. The objective of this review is to provide comprehensive information on the physiological, molecular and biological aspects of the three genetic constituents of flowering and maturity time in wheat. Reviews written in the past have covered either one of the aspects; and generally focused on one of the three genetic constituents of the flowering time. The current review provides (a) a detailed overview of all three gene systems (vernalization, photoperiod and earliness per se) controlling flowering time, (b) details of the primer sequences, their annealing temperatures and expected amplicon sizes for all known markers of detecting vernalization and photoperiod alleles, and (c) an up to date list of QTLs affecting flowering and/or maturity time in wheat. 相似文献
174.
Mohammad Ashik Iqbal Khan Kihachi Ueno Sakae Horimoto Fuminori Komai Kinji Tanaka Yoshitaka Ono 《Biology and Fertility of Soils》2009,45(3):305-313
The aims of this study were to monitor the changes in physicochemical, including spectroscopic, and biological characteristics
during composting of green tea waste–rice bran compost (GRC) and to define parameters suitable for evaluating the stability
of GRC. Compost pile temperature reflected the initiation and stabilization of the composting process. The pH, electrical
conductivity, NO3
−-N content, and carbon-to-nitrogen ratio were measured as chemical properties of the compost. The color (CIELAB variables),
humification index (the absorption ratio Q
4/6 = A
472 / A
664 of 0.5 M NaOH extracts), absorption at 665 nm of acetone extracts, and Fourier-transform infrared (FT-IR) spectra were measured
to evaluate the organic matter transformation; germination of komatsuna or tomato seeds was measured to assess the potential
phytotoxicity of composting materials during composting. No single parameter was capable of giving substantial information
on the composting process, the nutrient balance, phytotoxicity, and organic matter decomposition. The FT-IR spectra at 3,300,
2,930, 2,852, and 1,065 cm−1 provided information on the molecular transformation of GRC during composting and they decreased over the composting. Most
of the assayed parameters showed no further change after about 90 days of composting suggesting that GRC can be used for agricultural
purposes after this period. 相似文献
175.
Estrous expressions in dairy cows have been shortened and weakened. Dairy heifers, on the other hand, may not have had such changes in estrous signs as observed in cows, since they have less stresses than cows. The aim of this study was to describe the duration of estrus in a herd of dairy heifers. A total of 56 Holstein Friesian heifers estrus was synchronized using two different hormonal protocols. They were checked for primary and secondary estrous signs with the help of heat detection devices for 48 h at an interval of 4 h starting at 16.00 hour, one day after PGF2α treatment. Onset and end of standing estrus during 48 h observation period was recorded in 35 of the 44 heifers coming into estrus within 5 days after PGF2α treatment during the observation period. The duration of standing estrus on the average (±SD) was 9.7 ± 5.3 h. Percentage of heifers with standing estrus longer than 12 h was 40%, and 53% showed standing estrus only for 4–8 h. It is indicated that duration of estrus in dairy heifers has been shortened recently. 相似文献
176.
This project was conducted to investigate the comparative efficiency of competitive ELISA (cELISA), standard Agar Gel Immunodiffusion
Test (AGID) and Precipitinogen Inhibition Test (PIT) for the diagnosis of Peste des Petits Ruminants (PPR) in Pakistan. To deal with this, serum samples from 198 sheep and 82 goats were collected from three different government
livestock farms and all the samples were run simultaneously with the three serological tests. The samples found positive for
PPR antibodies through cELISA, AGID and PIT were 96 (34.2%), 60 (21.4%) and 72 (25.7%), respectively. Kappa statistics were
applied to evaluate the concordance between the laboratory-based test (cELISA) and field-based tests (AGID and PIT). Kappa
statistics scores for cELISA versus AGID and PIT were 0.6343 (95% Confidence Interval CI 0.5231–0.7456) and 0.7134 (95% Confidence
Interval CI 0.5987–0.8281), respectively, which indicate a “substantial” agreement between cELISA and AGID and “significant”
agreement between cELISA and PIT. AGID and PIT revealed relative diagnostic sensitivities with cELISA of 59.3% and 69.7% and
relative diagnostic specificities of 98.3% and 97.2%, respectively. The data suggested that for mass screening and control
of PPR, these serological tests proved practical in the absence of cELISA since they have high relative diagnostic specificities
and a satisfactory relative diagnostic sensitivities. 相似文献
177.
Iqra Javid Mahroze Fatima Syed Zakir Hussain Shah Muhammad Afzal 《Aquaculture Nutrition》2021,27(1):217-224
The effect of organic acids (OA) and dicalcium phosphate (Pi) supplementation in the feed of Labeo rohita fingerlings was studied by formulating seven practical diets, designed as D1 with no feed additives {dicalcium phosphorus (Pi) and organic acid (OA) blend} while, D2, D3, D4 and D5 were supplemented with Pi at the graded levels of 5, 10, 15 and 20 g/kg, respectively, whereas D6 and D7 contained blend of OA at 15 and 30 g/kg, respectively. The diet supplemented with OA blend exhibited increase (p < .05) in growth of L. rohita fingerlings compared with the diet supplemented with Pi. The OA supplementation at both levels showed significant improvement in nutrients digestibility and minerals absorption in fingerlings. Moreover, in case of muscle proximate composition, crude fat (CF) and crude protein (CP) were increased (p < .05) with the inclusion of OA blend in the diet while crude ash (CA) was improved by Pi supplementation. Additionally, digestive enzyme activities were not affected (p ? .05) by OA blend supplementation while increased activities were observed in the fingerlings fed with Pi diet. Consequently, supplementation of OA blend in the diet improved the growth performance and nutrient status while Pi enhanced digestive enzyme activities of L. rohita fingerlings. 相似文献
178.
Wira Wisnu Wardani Alimuddin Alimuddin Muhammad Zairin Junior Mia Setiawati Sri Nuryati Muhammad Agus Suprayudi 《Aquaculture Nutrition》2021,27(1):274-286
The experimental diets containing five levels of creatine supplementation, namely control (N = 0 g/kg creatine), B1 (1.00 g/kg glycine), B2 (0.40 g/kg creatine), B3 (0.80 g/kg creatine) and B4 (1.20 g/kg creatine) were tested to red tilapia up to apparent satiation 3 times a day for 56 days. After the feeding trial, fish were stressed by air exposure for challenge test against stress. The results described that creatine supplementation improved final body weight, feed conversion ratio (FCR) and protein retention. Creatine supplementation decreased blood glucose, cholesterol and triglyceride levels (p < .05), indicating more effective usage of non‐protein energy. Furthermore, creatine supplementation also increased plasma insulin levels and upregulated IGF‐1 and GLUT4 gene expressions in the liver significantly; it also improved robustness against stress, which was shown by higher superoxide dismutase, higher postchallenge survival and plasma cortisol, malondialdehyde and lower glucose levels. In conclusion, creatine supplementation at a dose of 0.289–0.389 g/kg diet escalated fish growth and improved robustness against stress via improving the SOD activity in red tilapia. 相似文献
179.
Methyl jasmonate alleviated salinity stress in soybean 总被引:1,自引:0,他引:1
Ji Young Yoon Muhammad Hamayun Su-Kyung Lee In-Jung Lee 《Journal of Crop Science and Biotechnology》2009,12(2):63-68
We studied the role of methyl jasmonate (MeJA) in alleviating NaCl-induced salt stress on soybean growth and development in
hydroponics medium. Soybean seedlings were exposed to 60 mM NaCl stress for 2 weeks, 24 h after the application of 20 and
30 μM MeJA. NaCl stress induced a significant reduction in plant growth, endogenous bioactive gibberellin (GA4), photosynthesis
and transpiration rate, while a marked increase in the endogenous abscisic acid (ABA) and proline contents were recorded.
MeJA application greatly mitigated the adverse effects of NaCl on soybean growth and endogenous hormones. MeJA significantly
increased ABA levels, while the endogenous amount of GA4 was reduced by the application of NaCl. Our study revealed that MeJA
counteracted the negative effects of NaCl stress on plant growth, chlorophyll content, leaf photosynthetic rate, leaf transpiration
rate, and proline content. 相似文献
180.