全文获取类型
收费全文 | 387篇 |
免费 | 10篇 |
专业分类
林业 | 24篇 |
农学 | 38篇 |
基础科学 | 5篇 |
99篇 | |
综合类 | 28篇 |
农作物 | 19篇 |
水产渔业 | 14篇 |
畜牧兽医 | 112篇 |
园艺 | 13篇 |
植物保护 | 45篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 9篇 |
2019年 | 4篇 |
2018年 | 14篇 |
2017年 | 12篇 |
2016年 | 19篇 |
2015年 | 2篇 |
2014年 | 7篇 |
2013年 | 34篇 |
2012年 | 13篇 |
2011年 | 18篇 |
2010年 | 11篇 |
2009年 | 11篇 |
2008年 | 13篇 |
2007年 | 24篇 |
2006年 | 23篇 |
2005年 | 7篇 |
2004年 | 12篇 |
2003年 | 4篇 |
2002年 | 5篇 |
2001年 | 10篇 |
2000年 | 5篇 |
1999年 | 9篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 6篇 |
1979年 | 4篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1973年 | 3篇 |
1971年 | 4篇 |
1970年 | 3篇 |
1969年 | 3篇 |
1968年 | 2篇 |
1967年 | 3篇 |
1952年 | 1篇 |
排序方式: 共有397条查询结果,搜索用时 15 毫秒
131.
Leaves of multipurpose tree species (those providing more than one function or product of human use) can serve as sources of fer-tilizer for nutrient supply, especially nitrogen (N). In this study chop... 相似文献
132.
Ram Kushal Singh Sujeet Pratap Singh Dinesh Kumar Tiwari Shraddha Srivastava Surendra Bahadur Singh Mukut Lal Sharma Rakesh Singh Trilochan Mohapatra Nagendra Kumar Singh 《Euphytica》2013,191(3):333-353
Genetic improvement of sugar content in sugarcane would benefit from the availability of sufficient DNA markers and a genetic map. Genetic linkage maps were constructed to identify quantitative trait loci (QTLs) for seedling brix (SB), brix (B), sucrose percent in juice (SUC), stalk number (SN), stalk length (SL), stalk diameter (SD), internodes (INT), number of green leaves (NGL), at three crop cycles across seven environments in a segregating population with 207 individuals derived from a bi-parental cross of sugarcane elite cultivars. Linkage analysis led to the construction of eight linkage groups (LGs) for Co86011 and sixteen LGs for CoH70. The combined length of the two linkage maps was 2606.77 cM distributed over 24 LGs. 31 QTLs were identified: 2 for SB, 7 for B, 6 for SUC, 4 for SN, 1 for SL, 3 for SD, 6 for INT and 2 for NGL at LOD scores ranging from 2.69 to 4.75. 7 QTLs (22 %) had stable effect across crop year and locations. Markers from parents were found to be associated with both positive and negative effect on all of the traits analyzed. The most important QTLs intervals identified in this study using single-dose marker, were qB2, qSUC2, qINT2 and qB2, qSUC2, qSL2, qINT2 located between SSR markers UGSM31548 and UGSM31649. These QTLs could be put into use in marker assisted breeding. 相似文献
133.
Abstract Larval rohu Labeo rohita were fed four different diets: three of the diets contained Achyranthes aspera (prickly chaff-flower) seeds at 0.10% (D1), 0.25% (D2), or 0.50% (D3); the fourth diet was a control diet (D4; no A. aspera supplementation). After 70 d, the rohu were injected intraperitoneally with live Aeromonas hydrophila. Mortality of fish was recorded for 7 d. In the D4 group, the first mortality was observed within 12 h of exposure, whereas in the D1–D3 treatment groups, mortality was first observed at 24 h postexposure. In the D4 group, 50% of fish died within 72 h of exposure, whereas in the D3 group, 10–15% mortality occurred between 72 and 84 h. The cumulative mortality rate was 50% for D4, 40% for D1, 35% for D2, and 15% for D3. Total tissue protein level in the larvae was higher for the D2 and D3 groups than for the other groups. Glutamic oxaloacetic transaminase, glutamate pyruvate transaminase, and thiobarbituric acid reactive substance levels were significantly lower in D3 larvae than in the other groups, whereas lysozyme and nitric oxide synthase levels were significantly higher in D3 larvae compared with the other groups. Dietary supplementation with A. aspera seeds at the 0.50% level provided protection against oxidative stress, prevented tissue damage, and enhanced disease resistance in rohu larvae. Received December 26, 2011; accepted May 7, 2012 相似文献
134.
Naveen Kumar Girish Chand Srivastava Kiran Dixit 《The Journal of Horticultural Science and Biotechnology》2013,88(4):520-524
SummaryThe roles of sucrose synthase and invertases were explored in relation to petal senescence in rose (Rosa hybrida L.). A developmental shift in the activities of these enzymes was observed. Higher sucrose synthase activity (0.52 – 0.95 µmol sucrose min–1 mg–1 protein) was observed during the initial stages (S1 and S2) of flower bud development, in contrast to invertases. However, the lower activity (0.56 µmol sucrose min–1 mg–1 protein) of sucrose synthase at a later stage (S6) of senescence could help the mobilisation of vacuolar sucrose. The different isoforms of invertase exhibited variable levels of activity. Insoluble acid invertases (IAI) were the most active (11.01 µmol glucose min–1 mg–1 protein), followed by soluble acid invertases (SAI; 8.02 µmol glucose min–1 mg–1 protein), and soluble neutral invertases (SNI; 0.74 µmol glucose min–1 mg–1 protein) at Stage-4. A significant decline in invertase activities (IAI, 0.98; SAI, 1.25; SNI, 0.32 µmol glucose min–1 mg–1 protein) coincided with higher levels of ethylene production at the later stages (S5 and S6) of flower bud development and senescence. We propose that developmental as well as ethylene-mediated pathways account for petal senescence in rose. 相似文献
135.
136.
Anjil Kumar Srivastava Parul Singh Ashok Kumar Singh 《Pesticide biochemistry and physiology》2008,91(3):186-190
In this study, the genotoxic effects of insecticides in different phases of cell cycle were investigated in the mitotic cells of barley (Hordeum vulgare L.). The seeds of H. vulgare L. Var. Karan 4 were treated with different concentrations (0.05%, 0.1% and 0.5%) of insecticides alphamethrin (AM) and monocrotophos (MP) for 6 h after synchronization of cells in G1, S and G2 phase of cell cycle with the help of various presoaking durations (7 h, 17 h and 27 h.). Positive and negative control was run parallel in the form of ethyl methane sulphonate (EMS) and distilled water, respectively. The data indicate that higher dose of alphamethrin and monocrotophos produce toxicity, chromosomal aberrations and mitotic aberrations in Hordeum vulgare L. The present study indicates the genotoxic potential of the insecticides AM and MP and it also showed that S-phase of cell cycle was more sensitive compared to the G1 and G2 phases. 相似文献
137.
水分胁迫下外源ABA对甘蔗叶绿素荧光特性的影响(英文) 总被引:2,自引:0,他引:2
以抗旱甘蔗品种ROC 22与不抗旱品种ROC 16为材料,研究水分胁迫条件下外源ABA对2个甘蔗品种叶片叶绿素含量及叶绿素荧光特性的影响。结果表明,水分胁迫下,ROC 16的叶绿素降解程度高于ROC 22,而外源ABA能够缓解这种降解作用;随着水分胁迫的加剧,两个甘蔗品种叶片的基础荧光(Fo)显著升高,PSⅡ原初光能转化效率(Fv/Fm)和PSⅡ的潜在活性(Fv/Fo)显著下降,光适应下PSⅡ最大光化学效率(Fv’/Fm’)、PSⅡ实际光化学效率(ΦPS2)、光化学猝灭系数(qP)显著下降,表明水分胁迫使甘蔗叶片PSⅡ反应中心受到伤害,施加外源ABA能部分减轻这种伤害,以对ROC 22作用尤为显著。 相似文献
138.
139.
Khyati Srivastava 《Pesticide biochemistry and physiology》2009,93(1):8-12
In the present study cytogenetic effects of atrazine herbicide, were examined on the root meristem cells of Allium cepa and Vicia faba. Test concentrations were chosen by calculating EC50 values of formulated atrazine against both the test systems which determined to be 30 mg l−1 for A. cepa and 35 mg l−1 for V. faba, respectively. For cytogenetic effects root meristem cells of A. cepa were exposed to 15, 30 or 60 mg l−1 whereas V. faba to 17.5, 35 or 70 mg l−1 for 4 or 24 h. Roots exposed for 4 or 24 h, after sampling, were left in water for 24 h recovery and sampled at 24 h post-exposure. A set of onion bulbs or seedlings of V. faba exposed to DMSO (0.3%) was run parallel for negative control. Treatment of atrazine significantly and dose-dependently inhibited the mitotic index (MI) and induced micronucleus formation (MN) chromosome aberrations (CA) and mitotic aberrations (MA) in both the test systems at 4 or 24 h. Root meristem cells examined at 24 h post-exposure also revealed significant (p < 0.001) frequencies of MN, CA or MA despite considerable decline. Chromosome breaks and fragments were found to be major CA whereas C-metaphase, chromosome bridges and laggards were prevalent MA. Results of our study, indicate that atrazine may produce genotoxic effects in plants. Further, both the plant bioassays found to be sensitive indicators for the genotoxicity assessment as the outcome of majority of in vivo/in vitro mammalian tests are comparable. 相似文献
140.
Vinod Kumar A. K. Chopra Sachin Srivastava 《Communications in Soil Science and Plant Analysis》2016,47(2):221-236
The assessment of heavy metals in spinach (Spinacia oleracea) grown in sewage sludge–amended soil was investigated. The results revealed that sewage sludge significantly (P < 0.01) increased the nutrients and heavy metals such as cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), and zinc (Zn) in the soil. The contents of metals were found to be below the maximum levels permitted for soils in India. The most agronomic performance and biochemical components of S. oleracea were found at 50% concentrations of sewage sludge in both seasons. The contents of Cd, Cr, Cu, Mn, and Zn in S. oleracea were increased from 5% to 100% concentrations of sewage sludge in both seasons. The order of contamination factor (Cf) of different heavy metals was Mn > Cd > Cr > Zn > Cu for soil and Cr > Cd > Mn > Zn > Cu for S. oleracea plants after application of sewage sludge. Therefore, use of sewage sludge increased concentrations of heavy metals in soil and S. oleracea. 相似文献