全文获取类型
收费全文 | 441篇 |
免费 | 20篇 |
国内免费 | 2篇 |
专业分类
林业 | 58篇 |
农学 | 20篇 |
40篇 | |
综合类 | 21篇 |
农作物 | 8篇 |
水产渔业 | 68篇 |
畜牧兽医 | 171篇 |
园艺 | 3篇 |
植物保护 | 74篇 |
出版年
2022年 | 3篇 |
2021年 | 11篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 13篇 |
2017年 | 12篇 |
2016年 | 9篇 |
2015年 | 13篇 |
2014年 | 26篇 |
2013年 | 33篇 |
2012年 | 19篇 |
2011年 | 20篇 |
2010年 | 11篇 |
2009年 | 14篇 |
2008年 | 16篇 |
2007年 | 26篇 |
2006年 | 29篇 |
2005年 | 25篇 |
2004年 | 26篇 |
2003年 | 20篇 |
2002年 | 23篇 |
2001年 | 25篇 |
2000年 | 11篇 |
1999年 | 14篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 6篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 1篇 |
1947年 | 1篇 |
1943年 | 1篇 |
排序方式: 共有463条查询结果,搜索用时 31 毫秒
451.
Asako Miyamoto Makoto Sano Hiroshi Tanaka Kaoru Niiyama 《Journal of Forest Research》2011,16(2):87-97
Land use and landscape changes, which have much effect on local biodiversity, are driven primarily by socioeconomic forces.
Understanding these forces is important for preservation of current biodiversity. In this study, we clarified the socioeconomic
forces that have brought about changes in the forest landscape around the Ogawa Forest Reserve in the southern Abukuma Mountains,
Japan, by interviewing local residents and reviewing local historical documents. Furthermore, we reconstructed past forest
landscapes and quantified the changes that have occurred from the beginning of the twentieth century until the present by
use of old land-use maps and past aerial photographs. The use of forest resources has dramatically changed during the past
hundred years, and it can be divided into three periods corresponding to the level of economic development. The main landscape
has changed significantly from one mainly composed of expansive grasslands and broad-leaved forests into a mosaic of fragmented
secondary forests and coniferous plantations. These landscape changes reflect shifts in both the use of forest resources by
local residents and the management of the national forests. Clarifying temporal–spatial landscape changes by understanding
the historical relationship between humans and the landscape provides useful information for optimizing conservation and management
planning. 相似文献
452.
Hibino T Hashimoto A Inoue T Tokuno J Yoshida S Sano M 《Science (New York, N.Y.)》2000,288(5473):2031-2033
The performance of a single-chamber solid oxide fuel cell was studied using a ceria-based solid electrolyte at temperatures below 773 kelvin. Electromotive forces of approximately 900 millivolts were generated from the cell in a flowing mixture of ethane or propane and air, where the solid electrolyte functioned as a purely ionic conductor. The electrode-reaction resistance was negligibly small in the total internal resistances of the cell. The resulting peak power density reached 403 and 101 milliwatts per square centimeter at 773 and 623 kelvin, respectively. 相似文献
453.
454.
Kim Y Sharov AA McDole K Cheng M Hao H Fan CM Gaiano N Ko MS Zheng Y 《Science (New York, N.Y.)》2011,334(6063):1706-1710
B-type lamins, the major components of the nuclear lamina, are believed to be essential for cell proliferation and survival. We found that mouse embryonic stem cells (ESCs) do not need any lamins for self-renewal and pluripotency. Although genome-wide lamin-B binding profiles correlate with reduced gene expression, such binding is not directly required for gene silencing in ESCs or trophectoderm cells. However, B-type lamins are required for proper organogenesis. Defects in spindle orientation in neural progenitor cells and migration of neurons probably cause brain disorganizations found in lamin-B null mice. Thus, our studies not only disprove several prevailing views of lamin-Bs but also establish a foundation for redefining the function of the nuclear lamina in the context of tissue building and homeostasis. 相似文献
455.
Assessing the use of erosion modeling to support payment for environmental services programs 总被引:1,自引:0,他引:1
Jorge Enoch Furquim Werneck Lima Walszon Terllizzie Araújo Lopes Fabiana de Gois Aquino Eduardo Cyrino Oliveira-Filho Edson Eyji Sano Felippe Damião Mello di Silva 《Journal of Soils and Sediments》2014,14(7):1258-1265
Purpose
Payment for environmental services (PES) has assumed increasing importance in discussions about sustainable development strategies. Many of the PES programs are based on water erosion control and the corresponding environmental and economic benefits generated in the basins where they are implemented. The main objective of this study was to show how erosion susceptibility models can support PES programs.Materials and methods
The application of the Universal Soil Loss Equation (USLE) in the Sarandi Experimental River Basin (32.7 km2), located in the Federal District, Brazil, was used as a study case. Then a scheme for organizing knowledge about ecosystem services related to erosion control and water resources was performed. Considering the generated scheme, the USLE results, the land use map, and the water use in the region, we evaluated how erosion modeling could support PES programs.Results and discussion
The results show that a large part of the study basin (90%) presents “low” susceptibility to erosion, which is significant in terms of the use and conservation of ecosystem services, as well as being a limitation regarding the need for the implantation of PES programs for erosion control. Incentives for maintaining the natural vegetation in areas with higher erosion susceptibility have the greatest potential to justify PES programs in the study basin, and the sanitation company is the potential payer for erosion control in the Sarandi River Basin.Conclusions
The application of the USLE in a spatially distributed form proved to be an important support tool for land management and the implementation of PES policies. 相似文献456.
Akinori Yamamoto Hiroko Akiyama Takuji Naokawa Yasuhiro Miyazaki Yusuke Honda Yukimasa Sano Yasuhiro Nakajima Kazuyuki Yagi 《Biology and Fertility of Soils》2014,50(1):53-62
Lime-N (calcium cyanamide, CaCN2) acts as both fertilizer and pesticide. Lime-N may reduce nitrous oxide (N2O) emission from soil, although its effectiveness and the relative mechanisms are not well understood. The aim of the study was to quantify the effect of lime-N on N2O emission from the acidic soil of tea fields. The study design consisted of two treatments: conventional fertilizer (CF) (application of conventional organo-chemical fertilizer) and lime-N (LN) (application of approximately 53 % of the applied N as lime-N and the remaining as conventional organo-chemical fertilizer). Both treatments had the same amount of N, P2O5, and K2O applied to soil between plant canopies; fertilizer was incorporated into soil. We measured N2O emissions and environmental and microbial parameters of soil between plant canopies and under the canopy of tea plants, including the concentrations of dicyandiamide and cyanamide derived from lime-N. Nitrous oxide emission from soil between plant canopies was lower in the LN treatment than in the CF treatment, and soil ammonium oxidation activity and soil denitrification rate decreased after lime-N application. We applied the acetylene inhibition technique and analyzed isotopomer ratios of N2O; the results of both techniques suggested that denitrification was the major process of N2O production in the soil between plant canopies, despite relatively low water-filled pore space. Cumulative N2O emission over the 366 days of the experiment was 36.0 % lower in the LN treatment than in the CF treatment (P?<?0.05). Our results suggest that lime-N application decreases N2O emission by inhibiting both nitrification and denitrification processes in the acidic soil. 相似文献
457.
Takehiko?Yokoyama Yuma?Mimura Minoru?Sato Eizoh?NagahisaEmail author 《Fisheries Science》2006,72(1):195-201
ABSTRACT: High levels of free d -alanine were found in the muscle of a marine gastropod Cellana grata that inhabited the intertidal zone, and alanine racemase activity was detected in the muscle. The authors purified alanine racemase from the muscle of C. grata to characterize its enzymological properties. The molecular mass of the enzyme was estimated to be 40.5 kDa by sodium dodecylsulfate-polyacrylamide gel electrophoresis and 41.4 kDa by gel filtration, suggesting that the enzyme was monomeric in nature. Kinetic experiments, performed using the purified enzyme, revealed that the Lineweaver-Burk plot for d -alanine as a substrate resulted in a K m value of 20.4 mM, and the value for l -alanine was 43.0 mM. Of the several types of amino acids tested, alanine was found to be the specific substrate for the enzyme. In the measurement of alanine racemase activity, exogenous pyridoxal 5'-phosphate (PLP) was not required for the enzyme activity; however, aminooxyacetic acid, hydroxylamine and phenylhydrazine, which inhibit PLP-dependent enzymes, strongly inhibited the enzyme activity. These results suggest that the enzyme is PLP-dependent. This is the first report on the purification and some properties of alanine racemase in a marine gastropod. 相似文献
458.
Genotyping‐by‐sequencing for construction of a new genetic linkage map and QTL analysis of growth‐related traits in Pacific bluefin tuna 下载免费PDF全文
Tsubasa Uchino Erina Hosoda Yoji Nakamura Motoshige Yasuike Miyuki Mekuchi Masashi Sekino Atushi Fujiwara Takuma Sugaya Yosuke Tanaka Kazunori Kumon Yasuo Agawa Yoshifumi Sawada Motohiko Sano Takashi Sakamoto 《Aquaculture Research》2018,49(3):1293-1301
Pacific bluefin tuna (Thunnus orientalis) has high market value, but its wild populations have decreased in recent years. The broodstock of Pacific bluefin tuna that were hatched artificially and reared under aquaculture conditions is beginning to be used for production. The creation of broodstock with commercially valuable traits, such as rapid growth, is therefore of great interest. Genetic linkage map‐based identification of markers associated with quantitative trait loci (QTLs) facilitates marker‐assisted selection (MAS) breeding and allows efficient genetic improvement of broodstock. Single nucleotide polymorphism (SNP)‐based genetic linkage map construction using the genotyping‐by‐sequencing method can expand the number of mapped markers and help identify growth‐related QTLs. In this study, we constructed sex‐specific maps for 24 linkage groups consisting of 677 SNP and 651 microsatellite markers. The total lengths of 93 progenies in the mapping population followed normal distribution, with an average length of 9.4 mm. We performed composite interval mapping in the mapping population. QTL analysis revealed one significant QTL in LG10 on the female linkage map. The genetic linkage map—the second such map generated for Pacific bluefin tuna—and the growth‐related QTLs detected in this study will be useful for tuna aquaculture MAS programs. 相似文献
459.
Functional insulin‐like factor 3 (INSL3) hormone‐receptor system in the testes and spermatozoa of domestic ruminants and its potential as a predictor of sire fertility 下载免费PDF全文
Ali M. Pitia Kyoko Uchiyama Hiroaki Sano Masashi Kinukawa Yoshiaki Minato Hiroshi Sasada Tetsuya Kohsaka 《Animal Science Journal》2017,88(4):678-690
Insulin‐like factor 3 (INSL3) is essential for fetal testis descent, and has been implicated in the testicular and sperm functions in adult males; however, similar functions in domestic ruminants remain largely unknown. This study investigated the functional INSL3 hormone‐receptor system in adult ruminant testes and spermatozoa, and explored its potential to diagnose the fertility of sires. Testes and spermatozoa were obtained from fertile bulls, rams and he‐goats, whereas subfertile testes and spermatozoa were obtained only from bulls. As expected, INSL3 was visualized in Leydig cells, while we clearly demonstrated that the functional receptor, relaxin family peptide receptor 2 (RXFP2), enabling INSL3 to bind was identified in testicular germ cells and in the sperm equatorial segment of bulls, rams and he‐goats. In comparison to fertile bulls, the percentage of INSL3‐ and RXFP2‐expressing cells and their expression levels per cell were significantly reduced in the testes of subfertile bulls. In addition, the population of INSL3‐binding spermatozoa was also significantly reduced in the semen of subfertile bulls. These results provide evidence for a functional INSL3 hormone‐receptor system operating in ruminant testes and spermatozoa, and its potential to predict subfertility in sires. 相似文献
460.
Apple dimple fruit viroid was detected from an apple tree (‘Jonagold’) bearing apples with mild dapple apple symptom. The isolates in Japan were distinct from those in apples in Italy and China and in fig in Italy. Graft-inoculation experiments showed that the symptoms were variable depending on the cultivar, and the symptom on ‘Starking Delicious’ was virtually similar to those reported in Italy. Symptoms induced by apple dimple fruit viroid were similar in part to those by apple fruit crinkle viroid or apple scar skin viroid, indicating that they cannot be discriminated by symptoms on any specific variety. 相似文献