全文获取类型
收费全文 | 616篇 |
免费 | 43篇 |
国内免费 | 3篇 |
专业分类
林业 | 49篇 |
农学 | 10篇 |
基础科学 | 1篇 |
81篇 | |
综合类 | 171篇 |
农作物 | 14篇 |
水产渔业 | 46篇 |
畜牧兽医 | 242篇 |
园艺 | 27篇 |
植物保护 | 21篇 |
出版年
2023年 | 10篇 |
2022年 | 14篇 |
2021年 | 21篇 |
2020年 | 18篇 |
2019年 | 22篇 |
2018年 | 23篇 |
2017年 | 23篇 |
2016年 | 10篇 |
2015年 | 24篇 |
2014年 | 16篇 |
2013年 | 36篇 |
2012年 | 47篇 |
2011年 | 66篇 |
2010年 | 25篇 |
2009年 | 20篇 |
2008年 | 28篇 |
2007年 | 31篇 |
2006年 | 28篇 |
2005年 | 25篇 |
2004年 | 20篇 |
2003年 | 24篇 |
2002年 | 14篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1999年 | 5篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1981年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1974年 | 3篇 |
1971年 | 4篇 |
1969年 | 3篇 |
1967年 | 3篇 |
1945年 | 2篇 |
1944年 | 2篇 |
1943年 | 3篇 |
1939年 | 2篇 |
1926年 | 2篇 |
1910年 | 3篇 |
排序方式: 共有662条查询结果,搜索用时 156 毫秒
151.
Catherine Belanger Catherine T. Gunther-Harrington Satoko Nishimura Maureen S. Oldach Samantha L. Fousse Lance C. Visser Joshua A. Stern 《Journal of Veterinary Cardiology》2018,20(2):115-122
Objectives
We aimed to evaluate safety and efficacy of high-pressure balloon valvuloplasty (HPBVP) for treatment of canine severe pulmonary valve stenosis (PS). A secondary aim was to provide pre-procedure predictors of success.Animals
Twenty-five dogs.Methods
Prospective observational study. Dogs with severe PS (echocardiographically derived trans-pulmonary peak/maximum pressure gradient (EDPG) ≥80 mmHg) were recruited. All dogs underwent echocardiography before and 20–24hrs after HPBVP using a high-pressure balloon with rated burst pressures ranging from 12 to 18 ATM. Procedural success was defined as a post-HPBVP EDPG reduction of ≥50% or reduction into at least the moderate category of PS (50–79 mmHg). Optimal result was defined as a post-procedural EDPG ≤30 mmHg.Results
Initial median (IQR) EDPG for all dogs was 96 (88, 127) mmHg with a post-operative median of 48 (36, 65) mmHg. The median EDPG reduction provided by HPBVP was 63% (39, 68); procedural success rate was 92% (23 dogs). Optimal results were achieved in 56% (14 dogs). There were no significant correlations between EDPG reduction and valve morphology (Type A and Type B) or severity of right ventricular hypertrophy. Pulmonary valve annulus diameter was the only echocardiographic variable that was significantly correlated to EDPG reduction (p = 0.02; r = ?0.46). No dog experienced any anesthetic or surgical complications, and all patients survived the procedure.Conclusions
In this cohort of 25 dogs with severe PS, HPBVP was safe and effective. The procedural success rate and high number of optimal results achieved with HPBVP suggest future randomized controlled trials comparing HPBVP to conventional valvuloplasty are warranted. 相似文献152.
Jonathan Simonsen Joshua Posner Martha Rosemeyer Jon Baldock 《Applied soil ecology》2010,44(2):147-155
Endogeic and juvenile anecic earthworm abundance was measured in soil samples and anecic populations were studied by counting midden numbers at the sites of two long-term cropping systems trials in South-central Wisconsin. The three grain and three forage systems at each site were designed to reflect a range of Midwestern USA production strategies. The primary objectives of this work were to determine if the abundance of endogeic or anecic earthworms varied among cropping systems or crop phases within a cropping system and were there specific management practices that impacted endogeic or anecic earthworm numbers. The earthworms present in the surface soil were: Aporrectodea tuberculata (Eisen), A. caliginosa (Savigny), A. trapezoides (Dugés); and juvenile Lumbricus terrestris (L.). True endogeic abundance was greatest in rotationally grazed pasture [188 m?2 at Arlington (ARL) and 299 m?2 at Elkhorn (ELK)], and smallest in conventional continuous corn (27 m?2 at ARL and 32 m?2 at ELK). The only type of anecic earthworm found was L. terrestris L. There was an average of 1.2 middens per adult anecic earthworm and the population of anecics was greatest in the no-till cash grain system (28 middens m?2 at ARL, 18 m?2 at ELK) and smallest in the conventional continuous corn system (3 middens m?2 at ARL, 1 m?2 at ELK). Earthworm numbers in individual crop phases within a cropping system were too variable from year-to-year to recommend using a single phase to characterize a whole cropping system. Indices for five management factors (tillage, manure inputs, solid stand, pesticide use, and crop diversity) were examined, and manure use and tillage were the most important impacting earthworm numbers across the range of cropping systems. Manure use was the most important management factor affecting endogeic earthworm numbers; but no-tillage was the most important for the juvenile and adult anecic groups and had a significantly positive influence on endogeic earthworm counts as well. The pesticides used, which were among the most commonly applied pesticides in the Midwestern USA, and increasing crop diversity did not have a significant effect on either the endogeic or anecic earthworm groups in this study. Consequently, designing cropping systems that reduce tillage and include manure with less regard to omitting pesticides or increasing crop diversity should enhance earthworm populations and probably improve sustainability. 相似文献
153.
154.
Skylar R. Sylvester Joshua G. Henry Parminder S. Basran Margaret C. McEntee 《Veterinary and comparative oncology》2023,21(3):378-390
Palliative-intent radiation therapy can alleviate pain and clinical signs in dogs with cancer, but optimal fractionation scheme is unknown. The objective of this retrospective case series is to evaluate clinical benefit, objective response, adverse effects, and outcomes in 108 dogs with macroscopic solid tumours treated with a cyclical “QUAD” hypofractionated palliative-intent radiation therapy protocol. Median QUAD dose was 14 Gy (14–16 Gy). Median total dose was 28 Gy (14–48 Gy). Clinical benefit rate was 93%, with median onset of subjective palliation 21 days after the first QUAD, lasting a median of 134 days. Tumour volumetric objective response was assessed with CT prior to the third QUAD in 36 dogs, with stable disease in 24 dogs (67%) and partial response in 9 dogs (25%). Sinonasal and oral were the most common tumour locations in 32 and 30 dogs, respectively. Median progression-free survival was 153 days (95% CI 114–200). Median overall survival was 212 days (95% CI 152–259). Number of QUAD cycles completed, clinical benefit achieved, anti-inflammatory received, total radiation dose, time to maximum clinical benefit, and response duration were positively associated with progression-free and overall survival. Acute toxicities were observed in 15 dogs (14%) with 3 high-grade (grade 3) toxicities (3%). Low-grade (grade 1 and 2) late skin and ocular toxicities were observed in 31 dogs (29%), predominantly leukotrichia, alopecia, keratoconjunctivitis sicca, and cataracts. This report demonstrates that QUAD radiation is an alternative protocol to be considered for palliation of dogs with inoperable or advanced stage solid tumours. 相似文献
155.
Objective
To characterize the incidence, contributing risk factors, and healing characteristics of immediate postoperative corneal erosions (IPCE) in dogs undergoing routine phacoemulsification.Animals Studied
Medical records of 313 canine eyes (159 dogs) undergoing routine phacoemulsification surgery.Procedures
Medical records of dogs undergoing planned cataract surgery at UW Veterinary Care were retrospectively reviewed. Patient-related variables including age, skull conformation, diabetes status, and cataract stage at the time of surgery were recorded. Intraoperative variables per eye were also recorded including surgical technique, surgeon expertise level, average phacoemulsification power, and phacoemulsification time. Diagnosis of IPCE ≤ 24 h after completion of surgery and time to IPCE healing were recorded where follow-up data were available.Results
Immediate postoperative corneal erosions were observed in 48/313 (15.3%) operated eyes. The presence of diabetes mellitus or brachycephalic skull conformation, preoperative Schirmer tear test (STT) value, surgical technique and surgeon experience level, phacoemulsification time, and absolute phacoemulsification time were not statistically significant risk factors for IPCE. Average phacoemulsification power was associated with IPCE (RR 1.52, p = .001). Time to IPCE healing was similar in diabetic and non-diabetic dogs (median [IQR] 8 [6–11] days and 8 [6–15] days, respectively). Diabetes mellitus, brachycephaly, and phacoemulsification parameters were not associated with IPCE healing at 7 or 14 days postoperatively.Conclusions
Higher average phacoemulsification power may be associated with the development of IPCE in canine eyes. The presence of diabetes mellitus or brachycephaly are not risk factors for the development of IPCE, nor are they factors that influence IPCE healing. 相似文献156.
R. Hobbs P.C. Catling J.C. Wombey M. Clayton L. Atkins A. Reid 《Agroforestry Systems》2003,58(3):195-212
We examined the faunal use of Eucalyptus globulus plantations in southern Western Australia, and compared use of remnant vegetation, agricultural land and plantations in different
positions relative to large tracts of remnant vegetation. In general, faunal use of plantations is less than in comparison
with adjacent remnant vegetation, but more than in open pasture. For all faunal groups there were almost twice as many species
recorded in the native vegetation than in any site in the plantations or on agricultural land and they were in greater abundance.
Faunal use of plantation edges and interiors did not show consistent patterns. Generally, edges next to remnants were most
frequently used, but individual species showed a wide range of patterns of use across the various habitat types studied. More
species of bird identified as being “at risk” were found in plantation edges than in interiors. Adjacency to remnant vegetation
increased plantation use by some species, but the overall differences between isolated plantations and those adjacent to remnant
vegetation were relatively small. We conclude that plantations provide some value in terms of habitat for some species, including
some of conservation concern, but that this value is limited by the lack of habitat complexity in the intensively-managed
plantations.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
157.
Joshua W. Beniston Rattan Lal Kristin L. Mercer 《Land Degradation \u0026amp; Development》2016,27(4):996-1006
Following the decline of industrial manufacturing, many US cities have experienced severe population reductions that have resulted in large areas of vacant land. Urban agriculture has emerged as a desirable land use for these spaces, but degraded soils are common. Therefore, we measured soil and plant responses to amendments and management in urban lots where vacant houses had recently been demolished in Youngstown, OH, USA. Soil degradation was observed following demolition activities in the form of compaction (bulk density of 1·5–1·8 Mg m−3) and low soil microbial biomass C (21 mg C kg−1 soil). Our split‐plot experiment measured the effects of organic matter (OM) amendments produced from yard wastes and the use of raised beds on soil properties and vegetable crop yields. Two years after their application, OM amendments resulted in significant improvement to a number of soil physical, chemical, and biological properties. Vegetable crop yields were improved by OM amendments in 2011 and by both OM amendments and the use of raised beds in 2012. A soil quality index, developed using factor analysis and the Soil Management Assessment Framework, produced values ranging from 0·60 to 0·85, which are comparable to those reported for rural agricultural soils. All results indicate that urban agriculture can be productive in vacant urban land and that amendments produced from urban yard wastes can improve soil quality at previously degraded sites and increase crop yields for urban agriculture. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
158.
159.
OBJECTIVE: To define landmarks on the canine ilial wing for accurate, consistent insertion of implants into the 1st sacral (S1) vertebral body when the sacroiliac joint is intact. STUDY DESIGN: Anatomic study. ANIMALS: Intact, cadaveric canine pelves and sacra (n=25). METHODS: Median sections (5 specimens) were drilled from the center of S1 in a lateral direction, exiting on the ilial wing. Landmarks on the ilial wing and shaft used to define this exit point were then used to locate this point on both wings of 20 articulated specimens, positioned and rigidly held so that the dorsal plane of the pelvis was aligned with a plumb line and the median plane of the pelvis was horizontal. A 2 mm hole was drilled from the marked point, parallel to the plumb line, until it exited the contralateral ilial wing. Distance of drill hole position from the geometric center (GC) of S1 was located on median and paramedian plane images derived from plane, computed tomographic (CT) scans. RESULTS: The entire drill hole was located within S1 in 18 specimens. Mean deviation of the hole from GC (ratio of the distance of GC from the closest S1 body border) in median section was 0.40 +/- 0.29 (craniocaudal direction) and 0.29 +/- 0.23 (dorsoventral). CONCLUSIONS: Use of ilial wing landmarks and drilling perpendicular to the median plane will improve accuracy for insertion of implants into S1 when the sacroiliac joint is intact. CLINICAL RELEVANCE: Ilial wing landmarks should be used to improve accuracy of implant insertion into S1. 相似文献
160.
Fach SJ Brockmeier SL Hobbs LA Lehmkuhl HD Sacco RE 《Veterinary immunology and immunopathology》2006,112(3-4):171-182
Lung dendritic cells (DCs) are potent antigen presenting cells (APCs) that initiate and modulate the adaptive immune response upon microbial infection within the pulmonary environment. For the first time, neonatal and adult lung DCs in a large animal model were compared in these studies. Here, we isolated and identified lung DCs in both neonatal and adult sheep, a valuable experimental animal utilized in pulmonary studies of naturally occurring respiratory diseases. Neonatal lung DCs exhibited characteristic dendrites and morphology when observed by transmission electron microscopy and expressed low to moderate DEC-205, CD80/86, MHC class II and CD 14. Regardless of age, lung DCs were functionally able to endocytose FITC conjugated ovalbumin but to a lesser degree than monocyte-derived DCs. In addition, neonatal lung DCs were demonstrated to be potent stimulators of allogeneic T cell proliferation. Together, these results demonstrate that neonatal and adult lung DCs are functionally similar. It is apparent from the data presented that neonatal pulmonary DCs do not exhibit an intrinsic functional defect that would impair their ability to take up antigen and stimulate na?ve T cells. These data support growing evidence that neonatal immune responses may differ from adults due to different microenvironmental influences rather than differences in dendritic cell maturation states. 相似文献