全文获取类型
收费全文 | 303篇 |
免费 | 13篇 |
国内免费 | 34篇 |
专业分类
林业 | 26篇 |
农学 | 43篇 |
基础科学 | 28篇 |
67篇 | |
综合类 | 69篇 |
农作物 | 11篇 |
水产渔业 | 25篇 |
畜牧兽医 | 62篇 |
园艺 | 7篇 |
植物保护 | 12篇 |
出版年
2023年 | 2篇 |
2022年 | 14篇 |
2021年 | 12篇 |
2020年 | 16篇 |
2019年 | 10篇 |
2018年 | 8篇 |
2017年 | 18篇 |
2016年 | 19篇 |
2015年 | 17篇 |
2014年 | 5篇 |
2013年 | 15篇 |
2012年 | 12篇 |
2011年 | 17篇 |
2010年 | 14篇 |
2009年 | 15篇 |
2008年 | 13篇 |
2007年 | 19篇 |
2006年 | 19篇 |
2005年 | 15篇 |
2004年 | 10篇 |
2003年 | 5篇 |
2002年 | 8篇 |
2001年 | 11篇 |
2000年 | 10篇 |
1999年 | 8篇 |
1998年 | 3篇 |
1997年 | 13篇 |
1996年 | 9篇 |
1995年 | 3篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1988年 | 3篇 |
1977年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有350条查询结果,搜索用时 15 毫秒
11.
AgcncrationrcfcrstoaIltrccsgencratcdinsamcPCriodoftimc.Tl1isisat`idcl}'ac-ccptedcol1ccpt.a11dtl1c111ostimPOrtantcharac-tcristicofgcncrationisgcncrationintcri'aloflime.TlcbiologicalcontcntisrcIati\'c1}'t'agucwhcnidcntif3'agcncrationonIyb}'mcansoftime.ltisPoi11tcdoutb}By31,lHlI(l985)tl1atagcncrationrcfcrstoalltl1ctrccst`11ichhax'csamcorigination,agc.morPho1og}',ccologica1proPCrt3'andPOsitionincom111unity,sotl1crcarcman}'`"a},stoidcntif3'gcncration.ltisjustbccauscofthcabundanccoftl1cconnota… 相似文献
12.
13.
Sadamasa ISHIKAWA Kou HIRAGA Yuuki HIRADATE Kentaro TANEMURA 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2015,77(6):725-728
Acetamiprid (ACE) and imidacroprid (IMI) are known neonicotinoid insecticides with strong
affinities for the insect-selective nicotinic acetylcholine receptor. These provide insect
control by hyperstimulating insect nerves and are used for agricultural pest management.
However, it has also been reported that ACE and IMI affect mammalian reproductive
function. We determined the effects of ACE and IMI on the in vitro
maturation of porcine oocytes. Significant decreases in nuclear maturation rates were
observed in the ACE or IMI-exposed groups. Also, in matured oocytes from the ACE or
IMI-exposed groups, irregular chromosomes were observed. Our results suggest that ACE and
IMI exposure was detrimental to porcine oocytes and the extent of the effects depends on
the concentration of exposure. 相似文献
14.
Atsushi IDETA Yoshito AOYAGI Kanami TSUCHIYA Yuuki NAKAMURA Kou HAYAMA Atsushi SHIRASAWA Kenichiro SAKAGUCHI Naomi TOMINAGA Yoshiyuki NISHIMIYA Sakae TSUDA 《The Journal of reproduction and development》2015,61(1):1-6
Embryos obtained via superovulation are necessary for mammalian artificial reproduction, and viability is a key determinant of success. Nonfreezing storage at 4 C is possible, but currently used storage solutions can maintain embryo viability for only 24–48 h. Here we found that 10 mg/ml antifreeze protein (AFP) dissolved in culture medium 199 with 20% (v/v) fetal bovine serum and 25 mM HEPES could keep bovine embryos alive for 10 days at 4 C. We used a recombinant AFP isolated from the notched-fin eelpout (Zoarces elongatus Kner). Photomicroscopy indicated that the AFP–embryo interaction was enhanced at 37 C. Embryos pre-warmed with the AFP solution at 37 C for 60 min maintained high viability, whereas those that were not pre-warmed could live no longer than 7 days. Thus, short-term storage of bovine embryos was achieved by a combination of AFP-containing medium and controlled pre-warming. 相似文献
15.
Wei HA Lian TW Tu YC Hong JT Kou MC Wu MJ 《Journal of agricultural and food chemistry》2007,55(26):10579-10584
Several antioxidant compounds have been previously identified from sword brake fern (Pteris ensiformis Burm.) by DPPH bleaching and Trolox equivalent antioxidant capacity (TEAC) analyses. Among the isolates, 7-O-caffeoylhydroxymaltol 3-O-beta-D-glucopyranoside and hispidin 4-O-beta- D-glucopyranoside [6-(3,4-dihydroxystyryl)-4-O-beta-D-glucopyranoside-2-pyrone] were two new compounds. The aim of this study is to elucidate the possible effect of the aqueous extract of sword brake fern (SBF) and these two compounds in preventing atherosclerosis. The results demonstrated that SBF and these two compounds strongly inhibited Cu2+-mediated low-density lipoprotein (LDL) oxidation measured by thiobarbituric acid-reactive substances assay (TBARS), conjugated diene production, and relative electrophoretic mobility. The commercial antioxidant dl-alpha-tocopherol showed lower antioxidant activity than these two compounds at the same molecular concentration. SBF and these two compounds also suppressed N-formylmethionyl-leucylphenylalanine (fMLP)-stimulated reactive oxygen species (ROS) production in human polymorphonuclear neutrophils (PMN). These findings indicate that sword brake fern may prevent atherosclerosis via inhibition of both LDL oxidation and ROS production. 相似文献
16.
17.
Effects of mangrove deforestation on fish assemblage at Pak Phanang Bay,southern Thailand 总被引:2,自引:0,他引:2
Tatsuya Shinnaka Mitsuhiko Sano Kou Ikejima Prasert Tongnunui Masahiro Horinouchi Hisashi Kurokura 《Fisheries Science》2007,73(4):862-870
Daytime sampling using a seine net was conducted at Pak Phanang Bay (Nakhon Si Thammarat Province, Thailand) in February and
July 2006, to determine differences in fish assemblage structures between a mangrove site and an adjacent site completely
cleared of mangroves. The overall numbers of fish species and individuals were significantly higher at the mangrove site than
the cleared site in both months. Although benthic crustacean feeders showed more species and individual numbers at the mangrove
site in both months, the opposite was found for zooplankton feeders. A cluster analysis, based on the abundance of each species,
demonstrated that the fish assemblage structures were distinctly different between the two sites. In addition, significant
differences in length frequency distributions for each of the four most abundant species were found between the sites in February
and/or July. Small individuals of Scatophagus argus, Ambassis nalua, and Tetraodon nigroviridis were more common at the mangrove site, and of Chelon subviridis at the cleared site. These results suggest that mangrove deforestation exerts marked effects on fish assemblages. 相似文献
18.
Since 1992, mass mortalities among cultured giant tiger shrimp, Penaeus monodon (Fabricius), and kuruma shrimp, Penaeus japonicus (Bate), have been observed in Taiwan. The condition is known as 'white spot disease' (WSD), based on the characteristic white spots on the cuticle of diseased shrimp. With the scanning electron microscope, two sizes of white spots were observed. Each spot represented a protrusion on the inside surface of the carapace. The composition of white spots was similar to that of the cuticule, most calcium, as determined with an energy dispersive spectrometer. Histological studies of moribund, infected specimens revealed degenerated cells, characterized by hypertrophied nuclei, in various meso- and ectodermal tissues. Infected tissues included cuticular epidermis, connective tissue, lymphoid organ, antennal gland, and haematopoietic, gill and nervous tissue. Nuclei were Feulgen-positive and no occlusion body was found in the necrotic tissue. Transmission electron microscopy revealed the presence of rod-shaped and enveloped virions in the hypertrophied nuclei. The virions measured 298 ± 21 × 107 ± 8 nm in the giant tiger shrimp and 248 ± 12 × 104 ± 8 nm in the kuruma shrimp. In an experimental infection trial, cumulative mortality was 40% within 14 days under stress conditions. No mortality was observed in controls or in non-stressed infected shrimp. Experimental infections show that environmental stressors such as ammonia may enhance the severity of WSD virus infections in cultured shrimp. 相似文献
19.
20.
体温是衡量母猪发情与否的关键生理指标。母猪发情期与间情期体温的明显不同,是运用红外热成像监测母猪体温变化以鉴定母猪发情的依据。该研究基于Y3TB01体温筛查智能摄像机和红外热像仪C3实时非接触拍摄母猪红外热图像,并运用图像分析技术获取体温,为非接触式测温用于鉴定母猪典型生理状态提供支持。试验以空怀期、发情期、妊娠1~8 d和妊娠9~16 d大白初产和经产母猪共720头为研究对象,利用红外设备和电子体温计分别测量母猪的眼睛、耳、耳蜗、乳房、外阴、臀部和直肠温度,筛选不同胎次发情母猪和返情母猪的体表关键部位温度,进行差异分析。结果表明:运用Y3TB01体温筛查智能摄像机可以代替直肠温度测定,准确监测母猪体表温度(相关系数为0.973);红外热像仪C3检测体温异常母猪的体表温度,臀部温度可以作为筛选大白初产发情母猪和返情母猪的测定部位(准确率分别为77%和72%),外阴温度可以作为筛选大白经产发情母猪和返情母猪的测定部位(准确率分别为88%和81%)。因此,Y3TB01体温筛查智能摄像机和红外热像仪C3配套技术能准确监测母猪体温和异常体温报警,明确不同胎次不同生理时期大白母猪体表部位温度和体温分布,准确鉴定出发情母猪和返情母猪。研究为非接触式测温鉴定母猪发情技术提供了科学依据,对规模化猪场母猪的饲养管理与疫情防控具有重要意义。 相似文献