全文获取类型
收费全文 | 3483篇 |
免费 | 202篇 |
专业分类
林业 | 946篇 |
农学 | 42篇 |
基础科学 | 4篇 |
576篇 | |
综合类 | 236篇 |
农作物 | 93篇 |
水产渔业 | 100篇 |
畜牧兽医 | 1501篇 |
园艺 | 53篇 |
植物保护 | 134篇 |
出版年
2021年 | 29篇 |
2020年 | 40篇 |
2018年 | 102篇 |
2017年 | 111篇 |
2016年 | 97篇 |
2015年 | 66篇 |
2014年 | 85篇 |
2013年 | 185篇 |
2012年 | 181篇 |
2011年 | 161篇 |
2010年 | 88篇 |
2009年 | 76篇 |
2008年 | 153篇 |
2007年 | 161篇 |
2006年 | 159篇 |
2005年 | 157篇 |
2004年 | 151篇 |
2003年 | 141篇 |
2002年 | 129篇 |
2001年 | 100篇 |
2000年 | 99篇 |
1999年 | 54篇 |
1998年 | 21篇 |
1997年 | 22篇 |
1996年 | 21篇 |
1995年 | 50篇 |
1993年 | 17篇 |
1992年 | 30篇 |
1991年 | 22篇 |
1990年 | 38篇 |
1989年 | 31篇 |
1988年 | 27篇 |
1986年 | 28篇 |
1985年 | 30篇 |
1984年 | 30篇 |
1983年 | 31篇 |
1982年 | 23篇 |
1981年 | 21篇 |
1980年 | 27篇 |
1979年 | 27篇 |
1978年 | 33篇 |
1976年 | 19篇 |
1975年 | 17篇 |
1974年 | 17篇 |
1973年 | 25篇 |
1971年 | 21篇 |
1970年 | 27篇 |
1969年 | 16篇 |
1956年 | 16篇 |
1937年 | 15篇 |
排序方式: 共有3685条查询结果,搜索用时 218 毫秒
81.
82.
Ohne Zusammenfassung 相似文献
83.
Loreida Timberg Kadri Koppel Rain Kuldjärv Edgar Chambers IV Aussama Soontrunnarudrungsri Suntaree Suwonsichon 《Journal Of Aquatic Food Product Technology》2013,22(6):552-566
The aim of the study was to describe and evaluate competitiveness of Estonian spice-cured sprat products in Estonia and Thailand. Sample A was saltiest, Sample B had lowest overall spiciness, and Sample C had highest pepper flavor and sour taste intensity. The main drivers of consumer acceptance for the spice-cured sprat products were different: flavor and appearance in Estonia and appearance and odor in Thailand. In Estonia, one cluster of consumers liked the traditional (Sample A) and lightly spiced (Sample B) sprat products, while the other cluster liked the traditional (Sample A) and the marinated (Sample C) sprat products. In Thailand, all samples scored low, but manual clustering indicated that marinated (Sample C) sprat products are most acceptable. The current study showed that spice-cured sprat products in general can be accepted by Thai consumers, especially as part of meals, if further flavor development is carried out with the products. 相似文献
84.
Effects of tagging on migration behaviour,survival and growth of hatchery‐reared Atlantic salmon smolts 下载免费PDF全文
R. Huusko A. Huusko A. Mäki‐Petäys P. Orell J. Erkinaro 《Fisheries Management and Ecology》2016,23(5):367-375
The effects of four different tagging methods (PIT, anchor T‐tag, Carlin tag and dummy radio transmitter) on survival, behaviour and growth of Atlantic salmon smolts during their downstream migration were examined in semi‐natural circular channels during a natural migration period in spring. Survival of smolts was high and tagging wounds healed well in all tagging groups. Tag loss rates were generally low, being the highest (2.5%) in the dummy radio transmitter group. Total length and body mass of the tagged and untagged smolts did not differ at the end of the experiment. Migration activity of smolts generally showed similar patterns among the treatments. However, Carlin‐tagged smolts started their migration slightly later than the PIT‐tagged fish, and smolts tagged with Carlin tag or dummy radio transmitter showed less overall migration activity than fish with PIT tag. 相似文献
85.
Digestates vary in composition and studies regarding their impact on C and N dynamics in soils are scarce. The objective was to analyse the C and N dynamics of digestates originating from various substrates applied to a sandy Cambisol and a silty Anthrosol. In three laboratory experiments (4–6 weeks), the effects of digestate properties, N rate and water content were tested. Averaged over both soils, 21% of the C supplied was emitted as CO2. Potential NH3 emissions during the first week ranged between 6% and 12% of NH4+ present in the digestates. The emission factors in the sandy Cambisol were on average 1.2 and 2 times higher for CO2 and potential NH3, respectively, compared to the silty Anthrosol. Similarly, net nitrogen mineralization in the sandy Cambisol was approximately twice the N mineralized in the silty Anthrosol. Net nitrification was not influenced by soil texture or different digestates, but increased with increasing application rates and had highest values at 75% of water holding capacity. Our results indicate that the type of substrate input for anaerobic digestion influences the properties of the digestate and therefore the dynamics of C and N. However, soil texture can affect these dynamics markedly. 相似文献
86.
Irene Vänninen Heikki Hokkanen Johanna Tyni‐Juslin 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):167-183
Finnish isolates of Beauveria bassiana (8 isolates), Metarhizium anisopliae (7), Tolypocladium sp. (2), Paecilomyces farinosus (2), P. fumosoroseus (1), Steinernema feltiae (3) and Bacillus thuringiensis ('Muscabac') were tested for efficacy against mixed populations of Delia radicum and D. floralis under field conditions in 1986–90. All pathogens were applied preventatively, the fungi as aqueous conidial or mycelial suspensions, dry conidia or dry mycelial powder. In only two of the nine experiments did B. bassiana or M. anisopliae give some control. In 1986, B. bassiana SF85–2 and Tolypocladium sp. SF85–4 (both at rate 1.2 x 109 conidia plant‐ 1), and ‘Muscabac’ (25 g 1?1, 1 dl plant?1) reduced the number of pupae by 80%, 60% and 50%, respectively, as compared with untreated and chemical (isophenphos) controls. In 1990, M. anisopliae SF86–39 at rate 1.6 x 109conidia plant?1 and 1.5 x 108 CFU plant?1 and S. feltiae SFS‐22 (35000 plant?1), increased the yield of cauliflower 2.2, 1.8, and 2.3‐fold, respectively, as compared with the untreated control, but these yields were only 19%, 15% and 19% of those of the chemical (diazinon) control. Paecilomyces isolates were ineffective in the 1986 experiment in which they were included. Our results suggest that it is difficult to find efficient control agents among the fungal and nematode species tested for use as biopesticides against cabbage root flies, but that the potential of M. anisopliae against these pests deserves further study. 相似文献
87.
88.
Stärk KD 《Schweizer Archiv für Tierheilkunde》2001,143(2):63-68
Sustainable animal production requires a healthy production system including healthy animals producing wholesome products. Epidemiology as a discipline is concerned with the occurrence of disease or disease indicators in populations as well as with factors influencing disease occurrence. By providing this information, epidemiology contributes significantly to the development and maintenance of healthy livestock. This is illustrated with the example of the enzootic pneumonia (EP) eradication programme of Switzerland. A series of observational studies were conducted in order to obtain the necessary knowledge to implement an area-wide EP eradication programme. The issues of economical eradication strategies at the herd level and the risk of re-infections were addressed. Simulation modelling and economical analysis were also applied. These research projects led to the successful start of a national eradication programme. The example of the EP eradication programme illustrates that applied epidemiological research provides critical information for the planning, implementation and evaluation of disease control programmes and is thus a key tool in developing sustainable animal production. 相似文献
89.
90.
Msami HM Khaschabi D Schöpf K Kapaga AM Shibahara T 《Tropical animal health and production》2001,33(5):367-377
When goats in Eastern Tanzania were screened for skin diseases, Dermatophilus congolensis was isolated from the skin lesions in 8 of 484 animals examined. In one severely affected case, the disease was also characterized by histological studies (Gram stain, Giemsa stain and routine HE studies) and electron microscopy. The histological picture was characterized by hyperkeratosis, parakeratosis, acanthosis, folliculitis and an inflammatory cellular reaction involving the epidermis. Gram stain and Giemsa stain revealed longitudinal and transverse branching filaments in the deeper layers of the epidermis. Ultrastructural studies demonstrated D. congolensis in various morphological forms, ranging from filamentous to tuber-shaped structures, mixed with numerous coccoid bodies of variable size. In some instances, the organisms were geometrically arranged in parallel rows of beading and were present in and among the degenerated epithelial cells. Several host cells showed degenerative changes. Ticks present on the goats were Amblyomma variegatum, Rhipicephalus evertsi, Rhipicephalus pravus and Boophilus sp. The clinical signs, pathological lesions, diagnosis, epidemiology and pathogenesis of the disease are discussed. 相似文献