全文获取类型
收费全文 | 36039篇 |
免费 | 1739篇 |
国内免费 | 2791篇 |
专业分类
林业 | 3907篇 |
农学 | 2772篇 |
基础科学 | 4657篇 |
4811篇 | |
综合类 | 17312篇 |
农作物 | 1449篇 |
水产渔业 | 880篇 |
畜牧兽医 | 2724篇 |
园艺 | 786篇 |
植物保护 | 1271篇 |
出版年
2024年 | 133篇 |
2023年 | 487篇 |
2022年 | 820篇 |
2021年 | 993篇 |
2020年 | 978篇 |
2019年 | 1056篇 |
2018年 | 681篇 |
2017年 | 1147篇 |
2016年 | 1469篇 |
2015年 | 1273篇 |
2014年 | 1992篇 |
2013年 | 1875篇 |
2012年 | 2887篇 |
2011年 | 3049篇 |
2010年 | 2341篇 |
2009年 | 2398篇 |
2008年 | 2274篇 |
2007年 | 2690篇 |
2006年 | 2239篇 |
2005年 | 1913篇 |
2004年 | 1424篇 |
2003年 | 1178篇 |
2002年 | 858篇 |
2001年 | 747篇 |
2000年 | 609篇 |
1999年 | 478篇 |
1998年 | 441篇 |
1997年 | 346篇 |
1996年 | 335篇 |
1995年 | 267篇 |
1994年 | 233篇 |
1993年 | 225篇 |
1992年 | 175篇 |
1991年 | 114篇 |
1990年 | 145篇 |
1989年 | 99篇 |
1988年 | 101篇 |
1987年 | 52篇 |
1986年 | 20篇 |
1985年 | 5篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1963年 | 1篇 |
1962年 | 3篇 |
1956年 | 3篇 |
1955年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
本文论述了我国植物性杀虫剂的生产和应用.及杀虫植物在我国的推广种植。对我国植物性农药生产和研究中的产品质量标准植物。性农药与化学农药的混配;持效期、稳定性、植物性农药的利用。与生态保护的关系等问题进行了讨论,建议加大对植物性农药的扶持力度。成立植物性农药质量标准专业委员会。 相似文献
993.
Rhamnolipids, extracellular metabolites of Pseudomonas aeruginosa with surfactant properties, proved to be very effective in controlling the spread of brown root rot disease caused by Phytophthora cryptogea in the hydroponic forcing system of witloof chicory ( Cichorium intybus var. foliosum ). The biosurfactant was applied as the product PRO1, a formulation of 25% rhamnolipids in oil. Both an in vitro screening and in vivo experiments in a mini-hydroponic system demonstrated the ability of PRO1 to control brown root rot. A 25 µ g mL−1 rhamnolipids nutrient solution was enough to obtain good control of an artificial infection with a zoospore suspension of P. cryptogea . The biosurfactant PRO1 performed well in a semicommercial system under growers' conditions. A treatment of 25 µ g mL−1 rhamnolipids (100 µ g mL−1 PRO1) reduced the disease incidence significantly in two independent experiments. However, PRO1 was not effective when a mycelial suspension was used as inoculum. Rhamnolipids have good potential to limit the spread of P. cryptogea in the hydroponic forcing system of witloof chicory, and can be used as a preventive measure against brown root rot. 相似文献
994.
During the period 2000–03, local potato cultivars in Estonia, Latvia, Lithuania, Poland and Denmark were tested for foliar resistance to Phytophthora infestans (late blight) in an international field trial network. Four standard cultivars were included in the trials: Sava, Oleva, Danva and Kuras. Primary disease-assessment data were entered into a common database, and parameters from the disease progress curves were calculated and made available on interactive web pages. A regression model, using relative area under disease progress curve (RAUDPC) values for cv. Oleva as a reference, was developed for the estimation of 1–9 scale values, where 1 = most susceptible. Standard deviations for the estimated 1–9 scale values and a nonparametric rank stability analysis of RAUDPC were used to evaluate the stability of resistance of the cultivars. Overall, the results showed stability of resistance for cvs Sava, Oleva and Danva, but not for Kuras. Use of the Internet-based Web-Blight service in this study facilitated comparison of results among countries for the level and stability of resistance. The estimated 1–9 scale values were similar to, or slightly lower than, those from official cultivar lists or from the European Cultivated Potato Database, especially for the more resistant cultivars. Possible reasons for discrepancies from different sources and locations are discussed. It is concluded that RAUPDC and the derived 1–9 scale values are useful for ranking cultivars for resistance to P. infestans , but this information is not detailed enough for use in a decision support system for late blight control. 相似文献
995.
996.
可视化技术在咸阳市水资源管理系统中的应用 总被引:2,自引:0,他引:2
运用现代数据库可视化管理技术,对长期以来咸阳市的水质、水量数据和资料进行系统分析和整理,提出了咸阳市水资源管理可视化的技术路线和系统设计方案,建立了咸阳市水资源可视化管理系统,为各职能部门提供科学管理手段,为技术人员进行决策提供科学依据,实现了水资源管理的规范化、高效化和快速化。 相似文献
997.
Allyson C. Berent DVM Jeffrey Todd DVM Jennifer Sergeeff DVM DACVIM Lisa L. Powell DVM DACVECC 《Journal of Veterinary Emergency and Critical Care》2005,15(2):128-135
Objective: To describe diagnostics, therapy, and sequelae of acute carbon monoxide (CO) toxicity because of a motor vehicle generator in 4 dogs and 2 cats. Series summary: Four dogs and 2 cats presented for recumbency, disorientation, dyspnea, and stiffness after an estimated 6–8 hour exposure to exhaust from a generator. Diagnostics included a serum carboxyhemoglobin levels evaluation, arterial blood gas analysis, pulse oximetry readings, and blood pressure measurements. Initial therapy included oxygen (O2) administration, intravenous bronchodilators, fluids, and a hemoglobin‐based O2 carrying (HBOC) molecule. Following administration of the HBOC, 4 of the 6 animals showed dramatic clinical improvement. Two weeks after hospital discharge, the owner reported potential hearing deficits in all animals. Brain auditory evoked response (BAER) tests were conducted in all surviving animals and some degree of hearing impairment was documented in all cases, with complete clinical resolution noted 6 weeks later. Unique information provided: This report describes the therapeutic use of an HBOC in acute isolated CO toxicity (i.e. without the complications of smoke inhalation). In addition, delayed nervous system dysfunction was documented in all surviving animals. 相似文献
998.
高速公路沙害防治技术研究-以丹东-拉萨高速公路新地-麻黄沟段为例 总被引:3,自引:0,他引:3
本文以新地—麻黄沟高速公路防沙体系效益为依据,探讨分析了高速公路沙害的特点以及防沙体系建设的基本要求。研究表明,高速公路沙害防治需要采取适当抬高路基,建立稳固的防沙体系并要适当加大防护带宽度的综合措施。该地区公路防沙体系的结构配置对干旱、半干旱沙漠地区高速公路沙害防治具有一定的借鉴作用。 相似文献
999.
Caroline Hennin Elke Diederichsen Monica Hfte 《Physiological and Molecular Plant Pathology》2001,59(6):287
Tomato and transgenic oilseed rape plants expressing the Cf-9 resistance gene develop a hypersensitive response (HR) after injection of the corresponding Avr9 gene product. It was investigated whether induction of a HR conferred resistance to different fungal pathogens in tomato and oilseed rape. Induction of an AVR9 mediated HR at the pathogen infection site delayed the development of the biotrophs Oidium lycopersicum in tomato and Erysiphe polygoni in oilseed rape, but enhanced the development of the necrotrophs Botrytis cinerea and Alternaria solani in tomato and Sclerotinia sclerotiorum in oilseed rape. Interestingly, delayed fungal disease development was observed in plant tissues surrounding the HR lesion regardless of whether a necrotrophic or biotrophic pathogen was used. In tomato, AVR9 injection induced systemic expression of PR1, PR2 and PR3 defence genes but did not induce systemic resistance to O. lycopersicum, B. cinerea or A. solani. In oilseed rape, AVR9 injection temporarily induced systemic resistance to Leptosphaeria maculans and E. polygoni, but did not induce detectable systemic expression of PR1, PR2 or Cxc750. These results give new insights into the potential uses of an induced HR to engineer disease resistance. 相似文献
1000.
Total labor time on paddy rice has been decreasing year by year with the development and introduction of appropriate herbicides, especially ‘one‐shot' herbicides. However, in the case of application of granules, it is still difficult for a farmer to apply herbicides while carrying heavy power backpack sprayers. New formulation recipes and different application technology such as a throw‐in type formulation on jumbo granules or flowable has improved heavy workloads in comparison with granule application by using heavy power backpack sprayers. In addition, other advantageous points such as application volume and elimination of the drift problems of this new application technology were introduced and confirmed. As a result of this introduction, these formulations were used in 830 000 ha and reached 30% of the total treatment area in paddy rice in 2000. 相似文献