全文获取类型
收费全文 | 625篇 |
免费 | 21篇 |
专业分类
林业 | 55篇 |
农学 | 63篇 |
基础科学 | 15篇 |
158篇 | |
综合类 | 29篇 |
农作物 | 53篇 |
水产渔业 | 71篇 |
畜牧兽医 | 135篇 |
园艺 | 7篇 |
植物保护 | 60篇 |
出版年
2023年 | 14篇 |
2022年 | 13篇 |
2021年 | 15篇 |
2020年 | 20篇 |
2019年 | 23篇 |
2018年 | 26篇 |
2017年 | 25篇 |
2016年 | 28篇 |
2015年 | 6篇 |
2014年 | 22篇 |
2013年 | 59篇 |
2012年 | 31篇 |
2011年 | 28篇 |
2010年 | 32篇 |
2009年 | 29篇 |
2008年 | 35篇 |
2007年 | 26篇 |
2006年 | 24篇 |
2005年 | 12篇 |
2004年 | 14篇 |
2003年 | 5篇 |
2002年 | 12篇 |
2001年 | 18篇 |
2000年 | 6篇 |
1999年 | 16篇 |
1998年 | 8篇 |
1997年 | 4篇 |
1995年 | 6篇 |
1994年 | 10篇 |
1993年 | 8篇 |
1992年 | 2篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1970年 | 1篇 |
1967年 | 1篇 |
1966年 | 3篇 |
排序方式: 共有646条查询结果,搜索用时 15 毫秒
101.
Daniela?Correia?MartinoEmail author Jorge?Luiz?Colodette Richard?Chandra Jack?Saddler 《Wood Science and Technology》2017,51(3):557-569
The steam explosion (SE) pretreatment associated with the organosolv process was investigated to produce dissolving pulp from eucalyptus. Prehydrolysis Kraft (PHK) pulping was also done to produce viscose and acetate grade pulps as reference. The organosolv pulps were delignified in two steps with sodium chlorite. Viscose and acetate grade PHK pulps were bleached by OD0(EH)D1P and OD0(EP)D1PCCE sequences, respectively. Dilute acid-catalyzed (with acid addition) SE pretreatment dissolved more xylan than auto-catalyzed (no acid addition) SE pretreatment. Steam-exploded unbleached organosolv pulps showed lower residual lignin content and screened yield than unbleached organosolv pulps without SE pretreatment. Steam explosion pretreatment helped to decrease lignin content and damaged fiber length of unbleached organosolv pulps. The 1.0% H2SO4 organosolv pulp (organosolv dissolving pulp at bioconversion conditions) showed the highest reactivity. Even showing low viscosity for some applications, in general, the organosolv dissolving pulps produced in this study can be used for making lyocell fibers. 相似文献
102.
103.
Mukesh Bhakat Tushar K. Mohanty Ashok K. Gupta Virendra S. Raina Biswajit Brahma R. K. Mahapatra M. Sarkar 《Tropical animal health and production》2010,42(7):1363-1366
Effect of Foot and Mouth disease (FMD) vaccination was studied on semen quality parameters of 19 Karan Fries (KF) and eight
Murrah (MU) breeding bulls during the period 2002 to 2004 at Artificial Breeding Complex, NDRI, Karnal. A total of non-vaccinated
155 KF and 72 MU bulls' ejaculates were taken as control, while 169 KF and 51 MU bulls' ejaculates, collected after vaccination,
were used to study the effect of vaccination stress. The results showed that FMD vaccination had no significant (P > 0.05) effect on ejaculate volume and total volume per day of semen in both KF and MU bulls. Volume of semen increased slightly
during post-vaccination period in both the breeds. After FMD vaccination, there was significant (P < 0.01) decrease in mass activity (2.27 ± 0.06 vs. 1.67 ± 0.07 and 2.49 ± 0.09. vs. 1.75 ± 0.10, for KF and MU, respectively),
initial motility (56.89 ± 0.03% vs. 44.62 ± 0.02% and 62.26 ± 0.04% vs. 47.08 ± 0.05%, for KF and MU, respectively), sperm
concentration (754.19 ± 23.96 vs. 554.14 ± 22.95 × 106/ml and 848.61 ± 33.65 vs. 571.57 ± 39.99 × 106/ml, for KF and MU, respectively), and total sperm output per ejaculate (3,685.94 ± 158.40 vs. 2,781.54 ± 151.70 × 106 and 2,218.75 ± 133.14 vs. 1,582.84 ± 158.20 × 106, for KF and MU, respectively). Application of FMD vaccine had significantly (P < 0.05) adverse effect on most of the seminal attributes during post-vaccination in KF and MU buffalo bulls. So, the spermiograms
affected following vaccination suggest that in bovines, the semen collection and preservation should be suspended till normal
fertility of sperm is restored to avoid the failure of conception from artificial insemination using such semen. 相似文献
104.
Krishna Mohan Vijay Kumar Mihir Sarkar B. S. Prakash 《Tropical animal health and production》2010,42(1):21-26
The objective of this study were (1) to establish the duration of behavioral estrus signs and timing of ovulation in Murrah
buffaloes (n = 10) and (2) to determine relationship between behavioral estrus signs with change in plasma estrogen concentrations.
Estrus and its behavioral signs were detected at hourly intervals by visual observations, per recta examination of genitalia
and bull parading four times in a day for 30 minutes each. Among the behavioral signs of estrus, swollen vulva (80%) was the
best indicator of estrus followed by excitement (70%). Among the duration of behavioral estrus signs the first and longest
duration of estrus signs was swollen vulva which was seen upto 19.8 ± 0.8 h after onset of estrus. The mean total duration
of estrus symptoms from appearance to disappearance of all the behavioral estrus symptoms was 23.5 ± 1.7 h. All the behavioral
estrus symptoms were observed during the period of estrogen surge. Endocrine profile during the periestrus period showed that
the mean peak concentrations of total estrogen 23.9 ± 3.9 pg/ml occurred at 8.8 ± 1.7 h after onset of estrus. The average
number of estrus symptoms observed per animal during onset of spontaneous estrus was 5.7. Ovulation occurred after 37.4 ± 1.7 h
after onset of estrus and 13.4 ± 1.0 h after end of total estrogen surge respectively. In conclusion, our results suggest
that all signs of behavioral estrus occurred during the preovulatory rise in estrogens. The first sign of estrus to be observed
was a swollen vulva and this symptom persisted the longest. 相似文献
105.
Identification of insect-damaged wheat kernels using short-wave near-infrared hyperspectral and digital colour imaging 总被引:1,自引:0,他引:1
Healthy wheat kernels and wheat kernels damaged by the feeding of the insects: rice weevil (Sitophilus oryzae), lesser grain borer (Rhyzopertha dominica), rusty grain beetle (Cryptolestes ferrugineus), and red flour beetle (Tribolium castaneum) were scanned using a near-infrared (NIR) hyperspecrtal imaging system (700-1100 nm wavelength range) and a colour imaging system. Dimensionality of hyperspectral data was reduced and statistical and histogram features were extracted from NIR images of significant wavelengths and given as input to three statistical discriminant classifiers (linear, quadratic, and Mahalanobis) and a back propagation neural network (BPNN) classifier. A total of 230 features (colour, textural, and morphological) were extracted from the colour images and the most contributing features were selected and used as input to the statistical and BPNN classifiers. The quadratic discriminant analysis (QDA) classifier gave the highest accuracy and correctly identified 96.4% healthy and 91.0-100.0% insect-damaged wheat kernels using the top 10 features from 230 colour image features combined with hyperspectral image features. 相似文献
106.
Hari Prasad Aithal MVSc PhD Prakash Kinjavdekar MVSc PhD Abhijit Motiram Pawde MVSc PhD Gaj Raj Singh MVSc PhD Harish Chandra Setia MSc 《Veterinary surgery : VS》2010,39(5):621-626
Objectives: To report the repair of tibial diaphyseal fractures in 2 calves using a circular external skeletal fixator (CEF). Study Design: Clinical report. Animals: Crossbred calves (n=2; age: 6 months; weight: 55 and 60 kg). Methods: Mid‐diaphyseal tibial fractures were repaired by the use of a 4‐ring CEF (made of aluminum rings with 2 mm K‐wires) alone in 1 calf and in combination with hemicerclage wiring in 1 calf. Results: Both calves had good weight bearing with moderate lameness postoperatively. Fracture healing occurred by day 60 in 1 calf and by day 30 in calf 2. The CEF was well maintained and tolerated by both calves through fracture healing. Joint mobility and limb usage improved gradually after CEF removal. Conclusions: CEF provided a stable fixation of tibial fractures and healing within 60 days and functional recovery within 90 days. Clinical Relevance: CEF can be safely and successfully used for the management of selected tibial fractures in calves. 相似文献
107.
A. K. Sarkar Ekta Rai Syed Naseer Shah Sulochna Bouddha Y. K. Bansal S. A. Ansari 《New Forests》2010,40(3):323-334
Changes in nitrate reductase, i.e. NR (E.C. 1.7.1.1) activity, peroxidase (E.C. 1.11.1.14) activity, soluble sugars and phenols were monitored at various time intervals from day 0 to 60 during in vitro adventitious shoot regeneration from leaflet explants of Albizia procera (Roxb.) Benth. The explants were incubated on semi-solid Murashige and Skoog medium supplemented with 2.6 g l?1 Phytagel®, 2.5% sucrose, 10 μM BAP, 1 μM NAA and 15 μM AgNO3. NR activity, soluble sugars and phenols exhibited initial sharp rise on around day 20 followed by steep decline on day 25, whereas peroxidase activity peaked on day 50, highlighting significance of early input of nitrogen and energy and late emergence of lignification process for cellular differentiation and organization into adventitious shoot primordia. Morpho-anatomical changes in leaflets at various stages of in vitro adventitious shoot formation also followed the endogenous biochemical pattern. 相似文献
108.
Effect of different biofloc system on water quality,biofloc composition and growth performance in Litopenaeus vannamei (Boone, 1931)
下载免费PDF全文
![点击此处可从《Aquaculture Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Muthusamy Rajkumar Pramod Kumar Pandey Radhakrishnapillai Aravind Alagarsamy Vennila Vivekanand Bharti Chandra Sekharan Purushothaman 《Aquaculture Research》2016,47(11):3432-3444
The experiment was conducted with three biofloc treatments and one control in triplicate in 500 L capacity indoor tanks. Biofloc tanks, filled with 350 L of water, were fed with sugarcane molasses (BFTS), tapioca flour (BFTT), wheat flour (BFTW) and clean water as control without biofloc and allowed to stand for 30 days. The postlarvae of Litopenaeus vannamei (Boone, 1931) with an Average body weight of 0.15 ± 0.02 g were stocked at the rate of 130 PL m?2 and cultured for a period of 60 days fed with pelleted feed at the rate of 1.5% of biomass. The total suspended solids (TSS) level was maintained at around 500 mg L?1 in BFT tanks. The addition of carbohydrate significantly reduced the total ammonia‐N (TAN), nitrite‐N and nitrate‐N in water and it significantly increased the total heterotrophic bacteria (THB) population in the biofloc treatments. There was a significant difference in the final average body weight (8.49 ± 0.09 g) in the wheat flour treatment (BFTW) than those treatment and control group of the shrimp. Survival of the shrimps was not affected by the treatments and ranged between 82.02% and 90.3%. The proximate and chemical composition of biofloc and proximate composition of the shrimp was significantly different between the biofloc treatments and control. Tintinids, ciliates, copepods, cyanobacteria and nematodes were identified in all the biofloc treatments, nematodes being the most dominant group of organisms in the biofloc. It could be concluded that the use of wheat flour (BFTW) effectively enhanced the biofloc production and contributed towards better water quality which resulted in higher production of shrimp. 相似文献
109.
Management of Pests and pesticides: Farmers’ Perceptions and Practices. Editors Joyce Tait and Banpot Napompeth, Boulder, Col.: Westview Press 1987. ISBN 0–8133–7174–0, £33 paperback. Termites in Buildings. Their Biology and Control. R. Edwards and A. Mill. Rentokil Library, 1987, ISBN 0906 5640 69 £24–50. Pesticide Science and Biotechnology. Proceedings of the Sixth International Congress of Pesticide Chemistry. Ottawa, Canada, 10–15 August 1986. Edited by R. Greenhalgh and T. R. Roberts. IUPAC/Blackwell Scientific Publications, 1987 (602 pp + xiii). Breeding for Resistance to Diseases and Insect Pests. By D. P. Singh. 222 pp + xi. ISBN 0 387 16970 9. Springer Verlag. 1986. Price $7900. Pest Control Safe for Bees: A Manual and Directory for the Tropics and Subtropics. By M. Adey, P. Walker and P. T. Walker, 1986. International Bee Research Association, London. Price £12–20. The Cocoa Pod Borer: An Introduction and Abstracts. Compiled by Lim Guan Soon et al. Malaysian Plant Protection Society, Box 12351 Kuala Lumpur. 1987. 103 pp. ISBN 967–9942–07–4. Pentachlorophenol. Environmental Health Criteria, No. 71, World Health Organization, Geneva, 1987. 236 pages, ISBN 92 4 154271 3. Price: Sw.fr. 18—/US$1080. Ecology and Control of Perennial Weeds in Latin America. FAO Plant Production and Protection Paper No. 4. Food and Agriculture Organization, Rome. 1986, 339 pp. ISBN 92–5–102446–4. Proceedings of the 2nd International Workshop on Leaf hoppers and Planthoppers of Economic Importance. Edited by M. R. Wilson and L. R. Nault. CAB International Institute of Entomology. 1987. 368 pp. ISBN 0–900301–03–1. Breeding for Durable Resistance in Perennial Crops. FAO Plant Production and Protection Paper No. 70 (1986). 130 pp. Ascochyta Blight Resistance in Chickpea. Proceedings of a training course, PARC/ICARDA, 3–10 March, 1984, Islamabad, Pakistan. ICARDA, 1986, 123 pp. 相似文献
110.
Anuj P. Srivastava Ramesh Chandra Sangeeta Saxena Shailendra Rajan Shirish A. Ranade 《The Journal of Horticultural Science and Biotechnology》2013,88(6):951-959
SummaryThree different PCR methods [Random Amplified Polymorphic DNA (RAPD), Inter-Simple Sequence Repeats (ISSR), and Directed Amplification of Minisatellite DNA (DAMD)] were used to analyse genetic diversity and parentage among 20 mango cultivars, including 18 landraces and two hybrids (‘Amrapali’ and ‘Mallika’). These hybrids together with a third hybrid (‘Ratna’), and an out-group species (Mangifera sylvatica) were also analysed for parentage. Fifteen, seven and four primers were used to amplify a total of 158, 69 and 59 distinct DNA fragments by RAPD, ISSR and DAMD, respectively. Of these, approx. 85%, 64% and 90% were polymorphic, respectively. Genetic distances between pairs of mango cultivars were measured separately by each method and depicted graphically as a Neighbor Joining (NJ) tree. The three methods revealed different groupings of cultivars and hybrids. A NJ tree based on the cumulative data from all methods correlated well with the parentage of the mango hybrids, and the grouping of cultivars on a regional basis. Genetic markers likely to be associated with important agronomic traits were identified by further analysing the hybrids, with their respective parents, using all three methods. On the basis of the highest number of polymorphic bands observed (90%), DAMD was judged to be the best method with which to analyse mango germplasm. 相似文献