全文获取类型
收费全文 | 6262篇 |
免费 | 460篇 |
国内免费 | 793篇 |
专业分类
林业 | 536篇 |
农学 | 1280篇 |
基础科学 | 282篇 |
1130篇 | |
综合类 | 2249篇 |
农作物 | 267篇 |
水产渔业 | 443篇 |
畜牧兽医 | 829篇 |
园艺 | 297篇 |
植物保护 | 202篇 |
出版年
2024年 | 35篇 |
2023年 | 118篇 |
2022年 | 211篇 |
2021年 | 236篇 |
2020年 | 265篇 |
2019年 | 311篇 |
2018年 | 195篇 |
2017年 | 272篇 |
2016年 | 355篇 |
2015年 | 273篇 |
2014年 | 348篇 |
2013年 | 417篇 |
2012年 | 477篇 |
2011年 | 458篇 |
2010年 | 433篇 |
2009年 | 356篇 |
2008年 | 281篇 |
2007年 | 331篇 |
2006年 | 309篇 |
2005年 | 280篇 |
2004年 | 223篇 |
2003年 | 200篇 |
2002年 | 137篇 |
2001年 | 138篇 |
2000年 | 110篇 |
1999年 | 109篇 |
1998年 | 82篇 |
1997年 | 72篇 |
1996年 | 75篇 |
1995年 | 51篇 |
1994年 | 56篇 |
1993年 | 45篇 |
1992年 | 54篇 |
1991年 | 42篇 |
1990年 | 40篇 |
1989年 | 24篇 |
1988年 | 23篇 |
1987年 | 18篇 |
1986年 | 9篇 |
1985年 | 10篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1955年 | 2篇 |
排序方式: 共有7515条查询结果,搜索用时 15 毫秒
81.
OBJECTIVE: The aim of this study was to characterize the clinical and morphologic features of neuronal ceroid lipofuscinosis (NCL) in the Polish Owczarek Nizinny (PON) breed of dog. ANIMALS: Nine Swedish PON dogs of both sexes were included in the study. PROCEDURE: All dogs underwent a detailed clinical evaluation, with emphasis on ophthalmic exams. Histopathology and electron microscopy were performed on the eyes, brain and various internal organs. Immunohistochemical staining for detection of sphingolipid activator proteins (SAPs) and mitochondrial ATP synthase (SCMAS) was performed on the eyes and brain. RESULTS: The dogs showed behavioral abnormalities, motor disturbances and visual impairment or blindness. Pupillary responses were abnormal while fundus changes varied from normal to severe retinal atrophy. Electroretinography (ERG) showed variable changes, from slight alterations in the process of dark adaptation to severely reduced or nonrecordable ERG a- and b-wave amplitudes. Histopathology revealed intracytoplasmic storage bodies within neurons of the brain and in retinal cells, especially the retinal pigment epithelium (RPE). Round to oval granular type of inclusion bodies, known as granular osmiophilic dense deposits (GRODS), were found in neuronal cells in the brain and in the retina. Immunohistochemistry identified the storage material in the brain and retina as consisting of SAPs. CONCLUSION: The presently described NCL disease in PON dogs shows similarities to previously recorded cases in the Miniature Schnauzer. The closest human equivalent to this disease is infantile NCL (CLN1), in which the major stored proteins are SAPs and the ultrastructure of the inclusion bodies of neuronal cells is granular. 相似文献
82.
83.
84.
Cao Changxiu Wang WanLiang 《保鲜与加工》1989,(5):68-75
The predictive intelligent control scheme is proposed, which is based on approximation theory and numerical method of Chcbyshev orthogonal polynomial. It has the practical value to the cold storge using widely electromagnetic valve and can be also applied similar systems in orther area. 相似文献
85.
The authors suggest that the land storage system is beneficial not only to strengthen the country's macroscopic regulation of city land market, accelerate healthy development of city economy and increase the financial income, it can also be advantageous to carry out the economic reform and public facilities construction without a hitch. On the basis of this, in this paper, the increment of the land price and house price as well as the high risk of fund due to lack of related laws is analyzed. Corresponding legal regulations, such as polishing the legislation of land right, implementing the land utilization planning, reinforcing the legislation of city development, land requisition and countryside residential land administration are put forward. 相似文献
86.
Chen Qigao Feng Ya 《保鲜与加工》1993,(1)
This paper analyses the thermal moist characteristics of the hull layer beside an air layer at lower temperature in an envelope for a cold storage and presents a new method of waterproof by air layer. With test data from engineering practice, the theory on the barrier of self moisture proof at the surface sublayer of the hull layer in an attic on a cold storage is proven. The dried zone about three phase point is confirmed. It is a new knowledge for thermophysics on thermal design of a cold storage with an optimum thermal performance. 相似文献
87.
以粮温实测数据为例探讨低温储粮的可行性 总被引:1,自引:0,他引:1
通过对高大平房仓粮温进行跟踪检测,分析比较了粮温变化情况,并探讨了低温储粮的可行性。 相似文献
88.
89.
采用不同的商品化处理工艺流程,经过XLF-2型柑桔鲜果处理机组进行柑桔商品化处理及贮藏试验,对其品质进行了分析得出:鲜果经杀菌处理后不宜再经清水清洗,若是经过了清水清洗的果实,在涂蜡时必须加入杀菌保鲜剂。经商品化处理后的鲜果,色泽亮丽,品质佳,保鲜效果好,明显增加了其商品性,并可延长其货架期,但不宜长时间贮藏。 相似文献
90.