全文获取类型
收费全文 | 2555篇 |
免费 | 133篇 |
专业分类
林业 | 219篇 |
农学 | 294篇 |
基础科学 | 31篇 |
576篇 | |
综合类 | 125篇 |
农作物 | 201篇 |
水产渔业 | 307篇 |
畜牧兽医 | 653篇 |
园艺 | 69篇 |
植物保护 | 213篇 |
出版年
2023年 | 36篇 |
2022年 | 74篇 |
2021年 | 82篇 |
2020年 | 104篇 |
2019年 | 125篇 |
2018年 | 153篇 |
2017年 | 151篇 |
2016年 | 119篇 |
2015年 | 83篇 |
2014年 | 119篇 |
2013年 | 225篇 |
2012年 | 180篇 |
2011年 | 164篇 |
2010年 | 138篇 |
2009年 | 95篇 |
2008年 | 106篇 |
2007年 | 100篇 |
2006年 | 85篇 |
2005年 | 62篇 |
2004年 | 50篇 |
2003年 | 47篇 |
2002年 | 31篇 |
2001年 | 39篇 |
2000年 | 34篇 |
1999年 | 27篇 |
1998年 | 18篇 |
1997年 | 16篇 |
1996年 | 10篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 11篇 |
1991年 | 15篇 |
1990年 | 13篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1987年 | 12篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 5篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1979年 | 14篇 |
1974年 | 8篇 |
1973年 | 8篇 |
1971年 | 7篇 |
1969年 | 6篇 |
1967年 | 4篇 |
排序方式: 共有2688条查询结果,搜索用时 15 毫秒
51.
The seeds of two soybean cultivars viz., Pusa-16 and PK-1042 were treated with 15, 30, and 45 kR of gamma rays, three concentrations
of ethyl methane sulphonate (EMS) (0.1%, 0.2%, and 0.3%), and their combinations. Various morphological mutants were recorded
in M2 and M3 generations. These morphological mutants were named on the basis of the part of the plant body affected. Eight different
morphological mutants, i.e., tall, dwarf, gigas, black pod, smooth pod, black spotted seed, bold seeded, and early maturing
were isolated. Among them, early maturing and bold seeded mutants had the potential to be incorporated into breeding programs. 相似文献
52.
Phosphorylation of tyrosine residues on sperm protein is a known indicator of capacitation and a major intracellular signalling event. There is evidence that sperm cryopreservation promotes tyrosine phosphorylation and is associated with reduced fertility of spermatozoa. Under this study, cryoprotective role of different additives namely taurine, trehalose, catalase and 4‐bromophenacyl bromide on buffalo sperm quality was evaluated. Buffalo semen was cryopreserved in tris‐based egg yolk extender supplemented with additives like taurine (50 mm ) or trehalose (100 mm ) or 4‐bromophenacyl bromide (200 μm ) or catalase (100 U/ml) and used for assessment of levels of tyrosine phosphorylation in frozen‐thawed spermatozoa. The results obtained were compared with the level of protein tyrosine phosphorylation of semen cryopreserved in tris‐based egg yolk extender without additives. Proteins were extracted from a total number of nine ejaculates from three individual buffalo bulls chosen at random and analysed for tyrosine phospho‐proteins using SDS–PAGE followed by immunoblotting. Monoclonal anti‐phosphotyrosine antibody (Clone pT‐154) was used as primary antibody followed by treatment with HRP‐conjugated secondary antibody. Signals were detected on X‐ray film using chemiluminescence. Nine proteins (p20, p30, p32, p38, p49, p56, p59, p72 and p86) were found to be tyrosine phosphorylated in cryopreserved spermatozoa. Supplementation of additives significantly (p<0.05) reduced the level of protein tyrosine phosphorylation in spermatozoa. Moreover, this study showed improved (p<0.05) post‐thaw motility, viability and membrane integrity of spermatozoa on addition of these additives. The results obtained clearly indicate reduced level of capacitation like changes on supplementation of additives in terms of protein tyrosine phosphorylation. 相似文献
53.
54.
Neuromuscular pedicle graft for restoration of arytenoid abductor function in dogs with experimentally induced laryngeal hemiplegia 总被引:1,自引:0,他引:1
C L Greenfield R Walshaw K Kumar C T Lowrie F J Derksen 《American journal of veterinary research》1988,49(8):1360-1366
Left laryngeal hemiplegia was induced by resection of the left recurrent laryngeal nerve in 12 dogs. A neuromuscular pedicle graft formed from the first cervical nerve and sternothyroideus muscle was transplanted after 1 week to the denervated cricoarytenoideus dorsalis muscle in 8 dogs. The remaining 4 dogs served as controls. Left arytenoid abduction was blindly evaluated by laryngoscopy with video photography at time 0, at 1 week, and at 19 weeks in all dogs. At 19 weeks, biopsy specimens of the left cricoarytenoideus dorsalis muscle and the neuromuscular pedicle were taken from 4 of the treatment dogs, and biopsy specimens of the left cricoarytenoideus dorsalis muscle were taken from the 4 control dogs. All biopsy specimens were blindly evaluated by histologic and histochemical examination. At 36 to 44 weeks, the remaining 4 treatment dogs, from which biopsy specimens had not been taken, were reevaluated by use of laryngoscopy with video photography. Complications and difficulties encountered during surgery included hemorrhage in the area of the cricoarytenoideus dorsalis muscle, location of a branch of the first cervical nerve that was long enough to prevent tension at the graft site, orientation of the muscle pedicle in the cricoarytenoideus dorsalis muscle without the use of an operating microscope, and preservation of the terminal portion of the first cervical nerve while forming the neuromuscular pedicle. Results of the arytenoid movement evaluations revealed improvement in arytenoid abductor function in the treatment group, compared with that in the control group at 19 weeks. Arytenoid abduction in the treatment group at this time, however, was still significantly decreased (P less than 0.05), compared with presurgical movement evaluations.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
55.
Akhilesh Kumar Vimal Chandra Pandey Anant Gopal Singh Divya Darshan Tewari 《Genetic Resources and Crop Evolution》2013,60(1):203-224
The aim of present study was to explore and document medicinal plants used for the traditional dermatological healthcare management practices by the the Tharu tribal community of Uttar Pradesh. The study was conducted during 2000–2004. Information was gathered from 230 informants residing in 46 villages in Terai region of Indo-Nepal boarder using questionnaires; oral interviews and group discussions. Total 92 medicinal plant species were cited for the preparation of 113 crude drug formulations. Voucher specimens of cited plant species were collected and identified as belonging to 82 genera and 49 families. Thirty-nine medicinal plant species were reported for the first time for dermatological healthcare problems from India. The dermatological healthcare problems managed were cut and wounds, ringworm, leprosy, eczema, scabies, leucoderma, boils, carbuncles, pimples, skin blemishes, spots, eruption, and burns etc. The most commonly and popularly used medicinal plant species for management of dermatological healthcare problems in the study area were Curcuma longa L., Azadirachta indica A. Juss and Melia azedarach L. It is concluded that dermatological healthcare management practice in the study area depends largely on wildly growing medicinal plant species. There is an urgent need to properly conserve the medicinal plant species growing in this area for human welfare. There is also need for further phytopharmacological studies to provide scientific explanation for the usages of 57 medicinal plant species for which to the best of our knowledge phytopharmacological literatures are not available. 相似文献
56.
Embryonic and larval developments of brackish water catfish,Mystus gulio (Hamilton and Buchanan, 1822) induced with human chorionic gonadotropin and consequent larval rearing 下载免费PDF全文
Prem Kumar Gouranga Biswas Tapas Kumar Ghoshal Muniyandi Kailasam Koyadan Kizhakedath Vijayan 《Aquaculture Research》2018,49(7):2466-2476
Mystus gulio, the long whiskers catfish, is a popular food fish and potential candidate species for aquaculture in Sundarban area of India and Bangladesh. Recently, catch of this species has declined due to overfishing and various ecological changes. In the present study, mature fish was induced to spawn in captivity through intramuscular injection of human chorionic gonadotropin at the doses of 10 IU/g to female and 5 IU/g to male. Photomicrographs of all developmental stages of live embryo and larvae were documented with the aid of a light microscope. Results demonstrated that morula, blastula, gastrula and neurula and organogenesis ended at 1:30‐, 3:00‐, 5:30‐, 7:30‐ and 17:15‐hour post‐spawning (hps) respectively. Heartbeat and muscular contraction of embryo commenced at 8:30 and 11.15 hps respectively. Hatching of embryo started after an incubation period of 17:30 hour at an ambient temperature of 29 ± 1°C. The newly hatched larvae measured 2.17 ± 0.29 mm in total length with a yolk volume of 0.165 ± 0.03 mm3 started feeding 36 hr after hatching. The present study, on induced breeding and chronological development of M. gulio embryo, will have significant implications on conservation and seed production for aquaculture. 相似文献
57.
Effects of biofloc under different carbon sources and protein levels on water quality,growth performance and immune responses in black tiger shrimp Penaeus monodon (Fabricius, 1978) 下载免费PDF全文
Sujeet Kumar Panantharayil S Shyne Anand Debasis De Ashutosh D Deo Tapas K Ghoshal Jitendra K Sundaray Alphis G Ponniah Karingalakkandy Poochirian Jithendran Ramalingam Ananda Raja Gouranga Biswas Natarajan Lalitha 《Aquaculture Research》2017,48(3):1168-1182
A 75‐day 2 × 3 factorial experiment was conducted to evaluate the effect of two levels of dietary protein (32 and 40%) and two different carbon sources (rice flour–R and molasses‐M), and without carbohydrate (control–C) in black tiger shrimp Penaeus monodon juveniles (3.37 ± 0.04 g) at 100 nos. m?3 in 100 L fibre reinforced plastic tanks. Biofloc volume and total suspended solid were higher in molasses added groups (32 + M and 40 + M) followed by rice flour (32 + R and 40 + R) and controls (32C and 40C). Molasses and rice flour addition significantly reduced (P < 0.01) the total ammonia–N compared to controls. The highest Vibrio, Bacillus and Lactobacillus counts were recorded in 40 + M, 32 + M and 32 + R respectively. Among the treatments, significantly higher (P < 0.01) final body weight was recorded in 40 + R (8.5 ± 0.3 g), 40 + M (7.8 ± 0.3 g) and 32 + R (7.5 ± 0.4 g) compared to control groups, 32C (6.1 ± 0.3 g), 40C (6.4 ± 0.3 g) and molasses added group, 32 + M (5.7 ± 0.4 g). Rice flour supplementation significantly increased (P < 0.01) the total haemocyte count (×106 cells mL?1) in 32 + R (45.7 ± 3.7) and 40 + R (44.3 ± 3.1) compared to controls, 32C (27.3 ± 3.4) and 40C (25.8 ± 0.9). Similarly, higher superoxide dismutase, catalase, serum protein and glucose were recorded in the rice flour added groups, 40 + R followed by 32 + R. Among the treatments, the highest level of prophenoloxidase (OD 490 nm, 0.3 ± 0.0) and survival after challenge with Vibrio harveyi (55.6%) was observed in 32 + R. The study elucidates that rice flour addition produces optimum level of biofloc with better growth and immune responses compared to molasses and control. Furthermore, rice flour addition at 32% protein level could replace 40% protein feed. 相似文献
58.
Omkar V. Byadgi K. M. Shankar B. T. Naveen Kumar Rajreddy Patil Iqlas Ahmed 《Aquaculture International》2014,22(2):887-900
A study was conducted on the stability of monoclonal antibody (MAb) in the hepatopancreas and hemolymph of Penaeus monodon and its effect on protection against white spot syndrome virus (WSSV) upon challenge. MAb C-5 raised against WSSV was purified and coated onto a commercial shrimp feed at dosages of 5, 10 and 15 mg/kg feed. The feed was fed to P. monodon and stability of the MAb in hepatopancreas and hemolymph was determined by immunodot and Western blot. Immunodot results indicated the presence of MAb for 2 h post-feeding in hepatopancreas and hemolymph which was dose-dependent. MAb was also detected in hemolymph by Western blot up to 1 h post-feeding. Shrimp fed with MAb were challenged with WSSV by oral and injection methods. In shrimp fed with 15 mg antibody/kg feed (0.45 μg MAb/g shrimp/day) WSSV infection significantly delayed both in oral and injection challenges with a survival of 65 and 70 % (p < 0.05), respectively, during 15 days post-challenge. MAb was stable in shrimp for passive immunization against WSSV and could be a potential tool for prophylaxis against the virus. 相似文献
59.
60.
Avinash Talukdar Ashutosh Dharmendra Deo Narrotam Prasad Sahu Parimal Sardar Muhammad Aklakur Satya Prakash Nazeema Shamna Sarvendra Kumar 《Aquaculture Nutrition》2020,26(3):921-935
A 60 days feeding trial was conducted to illustrate the effect of graded levels of protein on the growth and metabolic enzymes of grey mullet (Mugil cephalus L.) fingerlings reared in inland saline water (ISW). Six isoenergetic (16 MJ/kg) and isolipidic (60 g/kg) diets containing 240, 260, 280, 300, 320 and 340 g crude protein (CP)/kg diet were formulated and fed to triplicate. Weight gain %, specific growth rate, protein utilizing efficiency, feed efficiency and RNA:DNA ratio were significantly higher (p < .05) in 320 and 300 g CP/kg diets. Fish fed with 240 g CP/kg diet showed significantly higher (p < .05) feed intake, whole‐body lipid content, hepatosomatic index value and liver glycogen content. Transaminase enzymes and malate dehydrogenase activities were elevated in fish fed 340 g CP/kg diet. Protease activity increased with increasing dietary CP level, but amylase activities showed an inverse relationship. No significant (p > .05) variations were observed for lactate dehydrogenase, oxidative stress enzymes, blood parameters and serum osmolality among all the treatment groups, but red blood cell count increases with increasing dietary CP levels. Based on the results, feeding dietary protein level of 300 g CP/kg is economically viable for rearing of grey mullet in ISW. 相似文献