全文获取类型
收费全文 | 3119篇 |
免费 | 150篇 |
国内免费 | 2篇 |
专业分类
林业 | 59篇 |
农学 | 112篇 |
基础科学 | 25篇 |
335篇 | |
综合类 | 409篇 |
农作物 | 120篇 |
水产渔业 | 157篇 |
畜牧兽医 | 1770篇 |
园艺 | 58篇 |
植物保护 | 226篇 |
出版年
2021年 | 29篇 |
2020年 | 39篇 |
2019年 | 38篇 |
2018年 | 42篇 |
2017年 | 47篇 |
2016年 | 47篇 |
2015年 | 40篇 |
2014年 | 44篇 |
2013年 | 159篇 |
2012年 | 103篇 |
2011年 | 99篇 |
2010年 | 59篇 |
2009年 | 64篇 |
2008年 | 122篇 |
2007年 | 109篇 |
2006年 | 108篇 |
2005年 | 106篇 |
2004年 | 82篇 |
2003年 | 94篇 |
2002年 | 110篇 |
2001年 | 110篇 |
2000年 | 97篇 |
1999年 | 62篇 |
1998年 | 35篇 |
1997年 | 34篇 |
1996年 | 39篇 |
1995年 | 48篇 |
1992年 | 41篇 |
1991年 | 66篇 |
1990年 | 68篇 |
1989年 | 55篇 |
1988年 | 55篇 |
1987年 | 59篇 |
1986年 | 61篇 |
1985年 | 57篇 |
1984年 | 52篇 |
1983年 | 50篇 |
1982年 | 36篇 |
1981年 | 30篇 |
1979年 | 31篇 |
1978年 | 33篇 |
1977年 | 37篇 |
1976年 | 31篇 |
1975年 | 29篇 |
1974年 | 36篇 |
1973年 | 35篇 |
1972年 | 35篇 |
1971年 | 33篇 |
1970年 | 34篇 |
1969年 | 26篇 |
排序方式: 共有3271条查询结果,搜索用时 31 毫秒
1.
H. A. Narouei-Khandan S. P. Worner S. L. H. Viljanen A. H. C. van Bruggen E. E. Jones 《Plant pathology》2020,69(1):17-27
Myrtle rust (caused by Austropuccinia psidii) affects more than 500 known host species in the Myrtaceae family. Three different modelling approaches (CLIMEX, MaxEnt and Multi-Model Framework) were used to project the habitat suitability for myrtle rust at both global and local scales. Current data on the global occurrence of myrtle rust were collected from online literature and expert solicitation. Long-term averages of climate data (1960–1990) were sourced from WorldClim and CliMond websites. Recent reports of myrtle rust in New Zealand were used for validation of model outputs but not in model training and testing. The model outputs were combined into a consensus model to identify localities projected to be suitable for myrtle rust according to two or three models (hotspots). In addition to the locations where the pathogen is currently present, all models successfully projected independent occurrence data in New Zealand suitable for establishment of the pathogen. Climate suitability for the pathogen was primarily related to temperature followed by rainfall in MaxEnt and the CLIMEX model. The results confirmed the optimum temperature range of this pathogen in the literature (15–25 °C). Additional analysis of the precipitation variables indicated that excessive rain (more than 2000 mm in warmest quarter of the year) combined with high temperatures (>30 °C) constrain pathogen establishment. The results of the current study can be useful for countries such as New Zealand, China, South Africa and Singapore where the pathogen has not fully spread or established. 相似文献
2.
Therese M. McBeath Vadakattu V. S. R. Gupta Rick S. Llewellyn Sean D. Mason Christopher W. Davoren Raymond L. Correll Ben Jones Anthony M. Whitbread 《Journal of Agronomy and Crop Science》2019,205(6):635-646
A primary driver of the wheat yield gap in Australia and globally is the supply of nitrogen (N) and options to increase N use efficiency (NUE) are fundamental to closure of the yield gap. Co‐application of N with phosphorus (P) is suggested as an avenue to increase fertiliser NUE, and inputs of N and P fertiliser are key variable costs in low rainfall cereal crops. Within field variability in the response to nutrients due to soil and season offers a further opportunity to refine inputs for increased efficiency. The response of wheat to N fertiliser input (0, 10, 20, 40 and 80 kg N ha‐1) under four levels of P fertiliser (0, 5, 10 and 20 kg P ha?1) was measured on three key low rainfall cropping soils (dune, mid‐slope and swale) across a dune‐swale system in a low rainfall semi‐arid environment in South Australia, for three successive cropping seasons. Wheat on sandy soils produced significant and linear yield and protein responses across all three seasons, while wheat on a clay loam only produced a yield response in a high rainfall season. Responses to P fertiliser were measured on the sandy soils but more variable in nature and a consistent effect of increased P nutrition leading to increased NUE was not measured. 相似文献
3.
4.
5.
本论文研究了饲料加工的两个关键参数(调质温度和时间)对育肥猪颗粒饲料淀粉糊化度和维生素沉积的影响。日粮配方为含30%干酒糟及其可溶物的玉米-豆粕型基础日粮。整个试验中配方保持不变。本试验采用2×3双因子设计,调质温度分别为77℃和88℃,调质时间分别15秒、30秒和60秒。此外,本试验还设置一个对照组,对照组饲料不采用调质制粒工艺,而是采用粉料饲喂。因此,本试验共有7个处理组。采集调质后制粒前(热干粉)、制粒后冷却前(热制粒)、以及制粒冷却后(冷制粒)的样品,并分析这三种样品的总淀粉率、淀粉糊化 相似文献
6.
Stacie Aarsvold Jennifer A. Reetz Jean K. Reichle Ian D. Jones Christopher R. Lamb Maria G. Evola Michele A. Keyerleber Angela J. Marolf 《Veterinary radiology & ultrasound》2015,56(3):272-277
Primary pulmonary neoplasia is relatively uncommon in cats and generally has a poor prognosis. In this multicenter, retrospective study of 57 cats with pulmonary neoplasia, the most frequent presenting signs were anorexia/inappetence (39%) and cough (37%). The pulmonary tumors were considered to be incidental findings in 9% cats. In computed tomographic (CT) images, primary pulmonary tumors appeared as a pulmonary mass in 55 (96%) cats and as a disseminated pulmonary lesion without a defined mass in two (4%) cats. Most pulmonary tumors were in the caudal lobes, with 28 (49%) in the right caudal lobe and 17 (30%) in the left caudal lobe. CT features associated with pulmonary tumors included mass in contact with visceral pleura (96%), irregular margins (83%), well‐defined borders (79%), bronchial compression (74%), gas‐containing cavities (63%), foci of mineral attenuation (56%), and bronchial invasion (19%). The mean (range) maximal dimension of the pulmonary masses was 3.5 cm (1.1–11.5 cm). Additional foci of pulmonary disease compatible with metastasis were observed in 53% cats. Pleural fluid was evident in 30% cats and pulmonary thrombosis in 12% cats. The histologic diagnoses were 47 (82%) adenocarcinomas, six (11%) tumors of bronchial origin, three (5%) adenosquamous cell carcinomas, and one (2%) squamous cell carcinoma. In this series, adenocarcinoma was the predominant tumor type, but shared many features with less common tumor types. No associations were identified between tumor type and CT features. Prevalence of suspected intrapulmonary metastasis was higher than in previous radiographic studies of cats with lung tumors. 相似文献
7.
8.
P. David Jones Laurence R. Schimleck Richard F. Daniels Alexander Clark III Robert C. Purnell 《Wood Science and Technology》2008,42(5):385-400
A necessary objective for tree-breeding programs, with a focus on wood quality, is the measurement of wood properties on a
whole-tree basis, however, the time and cost involved limits the numbers of trees sampled. Near infrared (NIR) spectroscopy
provides an alternative and recently, it has been demonstrated that calibrations based on milled increment cores and whole-tree
data can provide good estimates of whole-tree properties. Several options exist for sampling standing trees and the aim of
this study was to compare wood property calibrations based on NIR spectra collected from samples obtained using different
sampling methods. Calibrations for whole-tree lignin and basic specific gravity based on NIR spectra from whole-tree chips
(milled or intact) had the strongest statistics, calibrations based on NIR spectra from milled increment cores were similar.
Other options for sampling the tree (drill shavings, etc.) gave errors that were too large for practical applications. If
an increment core is going to be used to estimate whole-tree properties, it is recommended that it be dried and milled prior
to analysis. 相似文献
9.
10.