全文获取类型
收费全文 | 760篇 |
免费 | 15篇 |
国内免费 | 1篇 |
专业分类
林业 | 92篇 |
农学 | 14篇 |
基础科学 | 1篇 |
210篇 | |
综合类 | 48篇 |
农作物 | 139篇 |
水产渔业 | 33篇 |
畜牧兽医 | 176篇 |
园艺 | 33篇 |
植物保护 | 30篇 |
出版年
2021年 | 10篇 |
2018年 | 9篇 |
2017年 | 10篇 |
2016年 | 12篇 |
2015年 | 7篇 |
2014年 | 17篇 |
2013年 | 51篇 |
2012年 | 27篇 |
2011年 | 28篇 |
2010年 | 9篇 |
2009年 | 18篇 |
2008年 | 29篇 |
2007年 | 25篇 |
2006年 | 35篇 |
2005年 | 27篇 |
2004年 | 28篇 |
2003年 | 28篇 |
2002年 | 22篇 |
2001年 | 20篇 |
2000年 | 10篇 |
1999年 | 23篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 8篇 |
1994年 | 9篇 |
1993年 | 11篇 |
1991年 | 12篇 |
1990年 | 8篇 |
1988年 | 6篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 6篇 |
1983年 | 11篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1976年 | 6篇 |
1975年 | 6篇 |
1972年 | 6篇 |
1970年 | 8篇 |
1969年 | 7篇 |
1965年 | 5篇 |
1959年 | 5篇 |
1941年 | 5篇 |
1940年 | 5篇 |
1936年 | 7篇 |
1935年 | 8篇 |
1934年 | 5篇 |
1928年 | 6篇 |
1926年 | 9篇 |
1924年 | 6篇 |
排序方式: 共有776条查询结果,搜索用时 15 毫秒
771.
772.
773.
T-helper cells from naive to committed 总被引:3,自引:0,他引:3
An endotoxin-induced mastitis model was used to study permeability changes associated with increased milk matrix metalloproteinase (MMP) activity in early inflammation. One quarter of two cows was inoculated with endotoxin (Escherichia coli 055:B5). Blood, milk, and whey were collected before and repeatedly after inoculation for 48 h. The profile and amounts of gelatinolytic MMPs were determined by zymography; gelatinase A (72 kD MMP-2) and gelatinase B (92 kD MMP-9) were identified by Western immunoblotting. Bovine serum albumin (BSA) and trypsin inhibitor capacity (TIC) were used as markers of capillary permeability with parallel examination of neutrophil penetration from blood to milk. Five clinical E. coli mastitis milk samples and five milk samples from cows with healthy udders were analyzed to detect whether increased levels of gelatinolytic MMP-2 and MMP-9 have a role in naturally occurring mastitis with endotoxin involvement. Milk MMP levels increased 2h after the endotoxin challenge. Both MMP-2 and MMP-9 were involved in this early proteolytic event. These increased MMP levels are associated with increased capillary permeability, evidenced first by the penetration of small molecular weight proteins, such as BSA and TIC. Later, 6-12h post endotoxin inoculation, neutrophilic leucocytes also entered the site, as they require larger tissue damage in basal membrane and interstitial tissue structures than BSA and TIC to extravasate. In naturally occurring disease, increased MMP-2 and MMP-9 levels were detected in milk. Thus, gelatinases, especially MMP-2, are involved in the early degradation of the blood-milk barrier, which precedes the penetration of blood-derived cellular components into milk in endotoxin-induced mastitis. In the future, measuring MMP in milk/whey might be a useful tool for diagnosing early mastitis. 相似文献
774.
The circulation over the continental shelf off the southern Middle Atlantic Bight (MAB) and northern South Atlantic Bight (SAB) is examined for the fall and winter periods. Observational data are compared with results from a three-dimensional numerical model to identify the dominant processes on the shelf. By considering wind-forcing, tides, and a specified upstream inflow (into the MAB), the observed and modelled flow fields are in close agreement in the mid- and inner shelf regions. The resulting larval drift indicates a seasonal dependence of transport pathways from spawning grounds to estuarine nursery areas for menhaden larvae and other offshore-spawning estuarine-dependent fish. Specifically, the physical oceanography of the MAB and SAB during the fall and winter months suggests a north-to-south shift in spawning areas providing recruits to the Carolina estuaries, in agreement with the observed migration of the spawning populations. 相似文献
775.
Aziz Tnibar Hans Schougaard Linus Camitz Jonas Rasmussen Marc Koene Werner Jahn Bo Markussen 《Acta veterinaria Scandinavica》2015,57(1)
Background
Polyacrylamide hydrogel (PAAG) was evaluated recently to treat osteoarthritis (OA) in horses with highly encouraging results; however no long term field-study was done to explore its clinical efficacy and lasting effect. The objective of this study was to evaluate the efficacy of PAAG in improving clinical signs of OA in horses. We hypothesized that lameness grade would significantly improve and the effect would last at least 2 years in osteoarthritic joints treated with PAAG. Forty three horses older than 2 years with OA in only one joint based on clinical evaluation, intra-articular anaesthesia and imaging (radiography) were included in this study. Horses were injected with 2 ml of PAAG into the affected joint and were followed up at 1, 3, 6, 12 and 24 months. Efficacy of PAAG was evaluated by blinded clinical assessment of lameness. Adverse reactions to joint injection were assessed. Data relating to case details, type of activity, joint and limb involved, lameness duration, lameness grading, previous joint treatment, joint effusion grading, radiographic grading, and owner assessment were recorded. Factors associated with the outcome measure “lameness grading” were analyzed using generalized linear mixed model for logistic regression.Results
At 1, 3, 6, 12 and 24 months follow-up, 59%, 69%, 79%, 81/% and 82.5% of horses were non-lame respectively. Reduction of joint effusion was observed over time. No side effect was observed in the treated joints. There was a significant decrease in lameness grade from baseline to 1, 3, 6, 12 and 24 months (P < 0.0001) and a significant positive association with joint effusion (P < 0.0001). Estimates for odds ratio (OR) showed that the effect of treatment increased over time (OR for lower lameness from month 1 to month 24 relative to baseline increased from 20 to 58).Conclusions
PAAG significantly alleviated lameness and joint effusion in osteoarthritic joints. PAAG is a safe and lasting (at least 24 months) OA treatment in horses. PAAG is a promising new treatment for OA in horses. 相似文献776.
The review is focused on studies presenting quantitative data and odor activity values (ratio of concentration to odor threshold) of key odorants in bread (wheat and rye), toasted bread, puff pastries made with different fats, fragrant and nonfragrant rices, sweet corn, popcorn, and tortillas. The influence of raw materials, processing parameters, and storage conditions on the concentrations of key odorants and some data on flavor precursors and formation pathways of these compounds are discussed. 相似文献