全文获取类型
收费全文 | 635篇 |
免费 | 54篇 |
专业分类
林业 | 50篇 |
农学 | 4篇 |
基础科学 | 3篇 |
77篇 | |
综合类 | 72篇 |
农作物 | 19篇 |
水产渔业 | 33篇 |
畜牧兽医 | 371篇 |
园艺 | 4篇 |
植物保护 | 56篇 |
出版年
2024年 | 1篇 |
2023年 | 9篇 |
2022年 | 11篇 |
2021年 | 22篇 |
2020年 | 14篇 |
2019年 | 22篇 |
2018年 | 15篇 |
2017年 | 20篇 |
2016年 | 22篇 |
2015年 | 18篇 |
2014年 | 30篇 |
2013年 | 24篇 |
2012年 | 62篇 |
2011年 | 54篇 |
2010年 | 28篇 |
2009年 | 36篇 |
2008年 | 45篇 |
2007年 | 51篇 |
2006年 | 48篇 |
2005年 | 39篇 |
2004年 | 29篇 |
2003年 | 16篇 |
2002年 | 23篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1972年 | 1篇 |
1965年 | 1篇 |
1958年 | 2篇 |
1954年 | 1篇 |
排序方式: 共有689条查询结果,搜索用时 101 毫秒
101.
Abelson JF Kwan KY O'Roak BJ Baek DY Stillman AA Morgan TM Mathews CA Pauls DL Rasin MR Gunel M Davis NR Ercan-Sencicek AG Guez DH Spertus JA Leckman JF Dure LS Kurlan R Singer HS Gilbert DL Farhi A Louvi A Lifton RP Sestan N State MW 《Science (New York, N.Y.)》2005,310(5746):317-320
Tourette's syndrome (TS) is a genetically influenced developmental neuropsychiatric disorder characterized by chronic vocal and motor tics. We studied Slit and Trk-like 1 (SLITRK1) as a candidate gene on chromosome 13q31.1 because of its proximity to a de novo chromosomal inversion in a child with TS. Among 174 unrelated probands, we identified a frameshift mutation and two independent occurrences of the identical variant in the binding site for microRNA hsa-miR-189. These variants were absent from 3600 control chromosomes. SLITRK1 mRNA and hsa-miR-189 showed an overlapping expression pattern in brain regions previously implicated in TS. Wild-type SLITRK1, but not the frameshift mutant, enhanced dendritic growth in primary neuronal cultures. Collectively, these findings support the association of rare SLITRK1 sequence variants with TS. 相似文献
102.
Robert J. Henry Nicole Rice Daniel L. E. Waters Shabana Kasem Ryuji Ishikawa Yin Hao Sally Dillon Darren Crayn Rod Wing Duncan Vaughan 《Rice》2010,3(4):235-241
Australian Oryza are an understudied and underexploited genetic resource for rice improvement. Four species are indigenous: Oryza rufipogon, Oryza meridionalis, Oryza australiensis are widespread across northern Australia, whereas Oryza officinalis is known from two localities only. Molecular analysis of these wild populations is required to better define the distinctness of the taxa and the extent of any gene flow between them and rice. Limited collections of these wild populations are held in seed and DNA banks. These species have potential for domestication in some cases but also have many traits of potential value in the improvement of domesticated rice. Stress tolerance (biotic and abiotic) and grain quality characteristics in these populations may be useful. 相似文献
103.
104.
Iridium-192 interstitial brachytherapy as adjunctive treatment for canine cutaneous mast cell tumors
Northrup NC Roberts RE Harrell TW Allen KL Howerth EW Gieger TL 《Journal of the American Animal Hospital Association》2004,40(4):309-315
Eleven dogs with cutaneous mast cell tumors (MCTs) were treated with surgery and iridium-192 ((192)Ir) interstitial brachytherapy. Minimum tumor doses ranged from 47.2 to 63.3 Gy. Treated tumors were classified as grade II (n=7) or III (n=4). Five dogs had recurrences with a median progression-free interval of 1391 days, and six dogs had no recurrence at a median follow-up time of 942 days. Acute adverse effects were well tolerated, and late effects were mild. One dog developed a second tumor of a different cell type in the radiation treatment field. 相似文献
105.
Nicole D. Peterson 《Agriculture and Human Values》2011,28(1):99-107
Participatory processes are often intended to encourage inclusion of multiple perspectives in defining management means and
goals. However, ideas about the legitimacy of certain uses and users of the resources can often lead to exclusion from participation.
In this way, participation can be transformed from a process of inclusion of various resource users to one of exclusion. Using
a case study from a marine protected area in Loreto, Baja California Sur, Mexico, and drawing on work in deliberative democracy,
I present a typology of how individuals and groups can be excluded from participation. External exclusion includes non-invitation
and other means for keeping participation from occurring. Internal exclusion refers to exclusionary events during participatory
meetings. This analysis suggests that participation needs to be recognized as a valuable but easily manipulated tool in the
design of projects like natural resource management. 相似文献
106.
107.
Tatiana C. Weisbrod Ramiro Isaza Carolyn Cray Laurie Adler Nicole I. Stacy 《The Veterinary quarterly》2021,41(1):30
Unique features of elephant hematology are known challenges in analytical methodology like two types of monocytes typical for members of the Order Afrotheria and platelet counts of the comparatively small elephant platelet. To investigate WBC differential and platelet data generated by an impedance-based hematology analyzer without availability of validated species-specific software for recognition of elephant WBCs and platelets, compared to manual blood film review. Blood samples preserved in ethylenediaminetetraacetic acid (EDTA) of 50 elephants (n = 35 Elephas maximus and n = 15 Loxodonta africana) were used. A Mann-Whitney test for independent samples was used to compare parameters between methods and agreement was tested using Bland-Altman bias plots. All hematological variables, including absolute numbers of heterophils, lymphocytes, monocytes, eosinophils, basophils, and platelets, were significantly different (p < 0.0001) between both methods of analysis, and there was no agreement using Bland-Altman bias plots. Manual review consistently produced higher heterophil and monocyte counts as well as platelet estimates, while the automated analyzer produced higher lymphocyte, eosinophil, and basophil counts. The hematology analyzer did not properly differentiate elephant lymphocytes and monocytes, and did not accurately count elephant platelets. These findings emphasize the importance of manual blood film review as part of elephant complete blood counts in both clinical and research settings and as a basis for the development of hematological reference intervals. 相似文献
108.
Abstract: Return migration has escaped significant analysis in the Pacific island region. Both migration from and return migration to the Tongan village of Nukunuku are for multiple reasons, with migration centred on employment and education, and return centred on the social context of home and duty. Return is limited, with intentions not being matched with practice, and the village and national population not growing. However, return migrants acquire skills, capital and experience overseas, which can be transferred into a Tongan cultural context, although identities have changed during migration. Return migrants typically take up employment or acquire businesses on return, gain some social status from the outcome, and are neither failures nor retirees. Nonetheless, return engenders expectations and tensions exist between returnees and more established residents, although ultimately, return migrants contribute to household, local and national development, as part of an unfinished process. 相似文献
109.
Atlantic salmon Salmo salar L. and brown trout Salmo trutta fario L. are species of high socio-economic and ecological value. Declining populations make them target species of fisheries management. This paper reviews the direct effects of deficient longitudinal connectivity, changes in discharge, high water temperatures, oxygen depletion, changes in water chemistry and increasing loads of fine sediment on the critical life stages of spawning, egg incubation and emergence. It further provides an overview about the basic autecological requirements of Atlantic salmon and brown trout and summarises important thresholds of physico-chemical tolerances. This collection of information provides important baselines for assessing historical, ongoing and new threats relevant for the management of both species in fresh waters. Critical early-life stages of both species are almost identical, creating synergies in conservation and restoration. Seaward-migrating forms are exposed to further stressors, but improving starting conditions can also greatly improve their resilience. 相似文献
110.
Li D Xu Y Shao CL Yang RY Zheng CJ Chen YY Fu XM Qian PY She ZG de Voogd NJ Wang CY 《Marine drugs》2012,10(1):234-241
Four new bisabolane-type sesquiterpenoids, aspergiterpenoid A (1), (-)-sydonol (2), (-)-sydonic acid (3), and (-)-5-(hydroxymethyl)-2-(2',6',6'-trimethyltetrahydro-2H- pyran-2-yl)phenol (4) together with one known fungal metabolite (5) were isolated from the fermentation broth of a marine-derived fungus Aspergillus sp., which was isolated from the sponge Xestospongia testudinaria collected from the South China Sea. Four of them (1-4) are optically active compounds. Their structures and absolute configurations were elucidated by using NMR spectroscopic techniques and mass spectrometric analysis, and by comparing their optical rotations with those related known analogues. Compounds 1-5 showed selective antibacterial activity against eight bacterial strains with the MIC (minimum inhibiting concentrations) values between 1.25 and 20.0 μM. The cytotoxic, antifouling, and acetylcholinesterase inhibitory activities of these compounds were also examined. 相似文献