全文获取类型
收费全文 | 26179篇 |
免费 | 530篇 |
国内免费 | 1044篇 |
专业分类
林业 | 4645篇 |
农学 | 2621篇 |
基础科学 | 1067篇 |
4261篇 | |
综合类 | 3702篇 |
农作物 | 2759篇 |
水产渔业 | 2209篇 |
畜牧兽医 | 2556篇 |
园艺 | 1488篇 |
植物保护 | 2445篇 |
出版年
2024年 | 51篇 |
2023年 | 145篇 |
2022年 | 342篇 |
2021年 | 494篇 |
2020年 | 421篇 |
2019年 | 435篇 |
2018年 | 3014篇 |
2017年 | 3103篇 |
2016年 | 1509篇 |
2015年 | 533篇 |
2014年 | 484篇 |
2013年 | 524篇 |
2012年 | 1429篇 |
2011年 | 2783篇 |
2010年 | 2688篇 |
2009年 | 1798篇 |
2008年 | 1844篇 |
2007年 | 2079篇 |
2006年 | 530篇 |
2005年 | 520篇 |
2004年 | 323篇 |
2003年 | 359篇 |
2002年 | 282篇 |
2001年 | 227篇 |
2000年 | 278篇 |
1999年 | 215篇 |
1998年 | 158篇 |
1997年 | 155篇 |
1996年 | 160篇 |
1995年 | 132篇 |
1994年 | 105篇 |
1993年 | 131篇 |
1992年 | 108篇 |
1991年 | 86篇 |
1990年 | 62篇 |
1989年 | 64篇 |
1988年 | 53篇 |
1987年 | 36篇 |
1986年 | 25篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1977年 | 4篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1968年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
241.
María Teresa Tejedor-Junco Margarita González-Martín Estefanía Bermeo-Garrido Rebeca Villasana-Loaiza Elena Carretón-Gómez 《Veterinary research communications》2018,42(3):227-232
Doxycycline is an antibiotic that, in addition to the classic antibacterial use, is also prescribed to fight parasitic diseases, like heartworm disease in dogs. Despite the concern that the overuse of this antibiotic may decrease susceptibility of clinically important bacteria, the consequences of the prolonged doxycycline therapy in heartworm-infected dogs have never been studied before. We have analyzed the impact of this therapy on Staphylococcus aureus and Enterococcus antimicrobial resistance. In this study, 17 heartworm-infected dogs (10 that had completed the doxycycline treatment and 7 dogs that had not yet begun) were included. Twenty-four isolates of Staphylococcus aureus were obtained from two locations of each dog. After treatment, 73.3% of isolates were resistant to at least one antibiotic but only 22.2% of isolates before treatment. Most of doxycycline resistant isolates were obtained from dogs that have received treatment. Erythromycin resistance or intermediate susceptibility was detected in 45.6% of isolates, most of them from dogs after treatment. For Enterococci, 48 isolates were obtained from fecal samples (25 before treatment and 23 after treatment). Before treatment, 32% of isolates were resistant at least to one antibiotic while after, this data increase up to 65%. Comparing isolates before and after treatment, a clear increase in resistance to doxycycline (12% against 21.74%) and erythromycin (20% against 39.13%) was observed. Although the present work is a preliminary research, the results encourages the development of further studies to determinate the effect of prolonged doxycycline therapy on antimicrobial resistance. 相似文献
242.
243.
Md. Aktaruzzaman Young-Gyu Lee Tania Afroz Byung-Sup Kim 《European journal of plant pathology / European Foundation for Plant Pathology》2018,150(1):245-251
In this study, we identified the causative agent of postharvest gray-mold rot in sweet persimmon fruit that were collected from Gangneung, Gangwon Province, Korea in October 2016. Symptoms included extensive growth of mycelia on post harvested fruit. The fungus was isolated from infected fruit and cultured on potato dextrose agar (PDA). For identification of the fungus, we examined morphology characteristics and rDNA sequencing analysis of the fungus and confirmed its pathogenicity according to Koch’s postulates. The results of morphological examinations, pathogenicity tests, 5.8S rDNA sequences of the internal transcribed spacer regions (ITS1 and ITS4) and the five nuclear protein-coding genes G3PDH, HSP60, RPB2, MS547 and TUB revealed that the causal agent of postharvest gray-mold rot on sweet persimmon fruit in Korea was Botrytis cinerea. 相似文献
244.
为了科学评估多年迷向防治对桃园梨小食心虫的实际防控效果,并完善优化桃园害虫性信息素科学应用技术,在江苏省无锡市惠山区5个乡镇大面积连片桃园内连续4年使用迷向丝防治梨小食心虫,并实时监测调查,分析各年度桃园内梨小食心虫种群消长动态,抽样法调查统计桃树折梢率。结果显示,多年迷向防治可以有效降低桃园梨小食心虫种群发生数量,各乡镇桃园内虫口基数逐年减少;洛社和钱桥2个乡镇2021年迷向防治处理区梨小食心虫平均迷向率在94.37%以上;2021年阳山镇迷向防治区平均折梢率为1.24%。结果表明大面积且连续使用迷向防治法对桃园梨小食心虫具有很好的防控效果。 相似文献
245.
Masabumi Komatsu Machiko Taniguchi Norihisa Matsushita Yukiko Takahashi Taizo Hogetsu 《Journal of General Plant Pathology》2010,76(6):363-369
Taphrina wiesneri, the pathogen of witches’ broom of cherry, is highly pathogenic to Cerasus × yedoensis, the most widely planted ornamental cherry species in Japan. For adequate control of this disease, it is necessary to understand
the life history of T. wiesneri. However, sites inhabited by T. wiesneri within infected trees are little understood, except during flowering and leafing periods in spring. Therefore, we attempted
to detect the location of T. wiesneri in shoots of witches’ broom before flowering and leafing in spring using PCR with a T. wiesneri-specific primer pair that was designed from 69 sequences in rDNA-internal transcribed spacer region of 32 Taphrina species. DNA extracted from symptomatic and asymptomatic C. × yedoensis sampled before leafing was amplified by PCR. T. wiesneri was detected in every bud and 5-mm stem segment of symptomatic shoots, except for one stem segment, and locally inside buds
and the inner bark of stem segments. These results indicate that T. wiesneri overwinters inside symptomatic shoots. Fungal hyphae were observed with an epifluorescence microscope in intercellular spaces
of young leaves in symptomatic buds but not in asymptomatic ones in thin sections stained with fluorescein-isothiocyanate-conjugated
concanavalin A. This observation supports the results of PCR detection. 相似文献
246.
Taissir Abou Al Fadil Alain Jauneau Yves Martinez Martina Rickauer Grégory Dechamp-Guillaume 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(1):93-103
Phoma macdonaldii, the causal agent of black stem disease of sunflower (Helianthus annuus), also attacks roots and collars of the plants, resulting in early death. Totally resistant lines do not exist for infection
of the aerial parts, but tolerant lines have been characterised. This paper presents a study on colonisation of a partially
resistant and a susceptible sunflower line by P. macdonaldii. The fungus was transformed with a constitutively expressed reporter gene encoding the jellyfish green fluorescent protein
via Agrobacterium tumefaciens, and colonisation of sunflower roots by this transformed strain was studied by various microscopy techniques including confocal
and scanning electron microscopy. The results show that penetration of the fungus into the root occurred through natural fissures
or through the epidermis and was similar in both lines. In contrast, the colonisation rate of the stele was reduced in the
partially resistant line, and the morphology of the fungal hyphae was also affected. The effect on hyphal morphology was strongest
in the stele, indicating a localised production of defence compounds in this line. 相似文献
247.
248.
Keisuke Tomioka Yuuri Hirooka Toshirou Nagai Hiroyuki Sawada Takayuki Aoki Toyozo Sato 《Journal of General Plant Pathology》2011,77(4):266-268
Severe blight of potted seedlings of monkshood caused by Plectosporium tabacinum was found in glasshouses in Kagawa Prefecture in southwest Japan in May 2001. Root rot and browning of stem bases were followed
by wilting and yellowing of leaves, then blighting of leaves, flower buds and stems. A fungus was isolated from diseased plants
and confirmed to cause the disease. The new disease was named “Plectosporium blight of monkshood”. 相似文献
249.
选择45头泌乳前期奶牛,根据年龄、胎次、泌乳时间和产奶量进行配对,随机分为对照组、试验Ⅰ组和试验Ⅱ组,各组均饲喂奶牛场配制的全混合饲料,另外,试验Ⅰ组每天每头奶牛日粮中添加45g奥奶净,试验Ⅱ组每天每头奶牛日粮中添加60g奥奶净,研究奥奶净对奶牛生产性能和血液生化指标的影响。结果表明,与对照组相比,补饲45g/d和60g/d奥奶净的奶牛产奶量分别提高了2.34%和2.96%(P〈0.05);乳脂率分别提高2.63%和6.72%;体细胞数分别下降了35.92%和42.55%(P〈0.05);磷酸肌酸激酶有提高的趋势,乳酸脱氢酶呈下降趋势;奶牛血清IgG、SOD和GSH-Px含量均有不同程度的提高,而MDA呈下降趋势。表明饲喂奥奶净能够促进奶牛泌乳、提高机体免疫力和机体抗应激能力.并有促进营养物质代谢的趋势。 相似文献
250.
Evi Pecceu Brittainy Stebbing Yolanda Martinez Pereira Ian Handel Geoff Culshaw Hannah Hodgkiss-Geere Jessica Lawrence 《Veterinary research communications》2017,41(4):249-256
Vasovagal tonus index (VVTI) is an indirect measure of heart rate variability and may serve as a marker of disease severity. Higher heart rate variability has predicted lower tumour burden and improved survival in humans with various tumour types. The purpose of this pilot study was to evaluate VVTI as a biomarker of remission status in canine lymphoma. The primary hypothesis was that VVTI would be increased in dogs in remission compared to dogs out of remission. Twenty-seven dogs were prospectively enrolled if they had a diagnosis of intermediate to high-grade lymphoma and underwent multidrug chemotherapy. Serial electrocardiogram data were collected under standard conditions and relationships between VVTI, remission status and other clinical variables were evaluated. VVTI from dogs in remission (partial or complete) did not differ from dogs with fulminant lymphoma (naive or at time of relapse). Dogs in partial remission had higher VVTI than dogs in complete remission (p = 0.021). Higher baseline VVTI was associated with higher subsequent scores (p < 0.001). VVTI also correlated with anxiety level (p = 0.03). Based on this pilot study, VVTI did not hold any obvious promise as a useful clinical biomarker of remission status. Further investigation may better elucidate the clinical and prognostic utility of VVTI in dogs with lymphoma. 相似文献