全文获取类型
收费全文 | 1806篇 |
免费 | 163篇 |
国内免费 | 3篇 |
专业分类
林业 | 97篇 |
农学 | 35篇 |
基础科学 | 8篇 |
177篇 | |
综合类 | 299篇 |
农作物 | 52篇 |
水产渔业 | 193篇 |
畜牧兽医 | 968篇 |
园艺 | 59篇 |
植物保护 | 84篇 |
出版年
2024年 | 3篇 |
2023年 | 34篇 |
2022年 | 32篇 |
2021年 | 45篇 |
2020年 | 77篇 |
2019年 | 72篇 |
2018年 | 78篇 |
2017年 | 69篇 |
2016年 | 67篇 |
2015年 | 47篇 |
2014年 | 71篇 |
2013年 | 89篇 |
2012年 | 114篇 |
2011年 | 164篇 |
2010年 | 101篇 |
2009年 | 67篇 |
2008年 | 116篇 |
2007年 | 90篇 |
2006年 | 78篇 |
2005年 | 70篇 |
2004年 | 80篇 |
2003年 | 70篇 |
2002年 | 61篇 |
2001年 | 16篇 |
2000年 | 15篇 |
1999年 | 11篇 |
1998年 | 18篇 |
1997年 | 18篇 |
1996年 | 23篇 |
1995年 | 13篇 |
1994年 | 12篇 |
1993年 | 17篇 |
1992年 | 18篇 |
1991年 | 20篇 |
1990年 | 18篇 |
1989年 | 17篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 3篇 |
1921年 | 2篇 |
1917年 | 2篇 |
1916年 | 2篇 |
1913年 | 2篇 |
1906年 | 1篇 |
1903年 | 1篇 |
1902年 | 1篇 |
排序方式: 共有1972条查询结果,搜索用时 15 毫秒
71.
B.D. Scott BS MS G.D. Potter PhD J.W. Evans PhD J.C. Reagor PhD G.W. Webb PhD S.P. Webb MS 《Journal of Equine Veterinary Science》1989,9(4)
Twenty-four yearlings were used to evaluate the efficacy of feeding feed-grade fat to growing horses. All horses were started on trial at 13-months-of-age and were fed for 112 days. The experimental diets, containing similar nutrient-to-calorie ratios, were: 1) control (no added fat; 2) 5% added fat and; 3) 10% added fat. There was a trend for yearlings fed the 10% added fat diet to grow faster and eat less feed than those on the control diet. Data from this study indicate that feed-grade fat can be safely fed to growing horses. Feeding fat to yearlings stimulated growth and efficiency of feed utilization initially, but these effects were not maintained as the yearlings grew toward maturity. 相似文献
72.
A comparison of epidural buprenorphine with epidural morphine for postoperative analgesia following stifle surgery in dogs 总被引:2,自引:1,他引:2
Lesley J Smith DVM Diplomate ACVA Jeff Kwang-An Yu BS 《Veterinary anaesthesia and analgesia》2001,28(2):87-96
Objective To compare the efficacy of epidural buprenorphine with epidural morphine for post‐operative pain relief in dogs undergoing cranial cruciate ligament rupture repair. Study design A randomized, double blind clinical trial. Animals Twenty client‐owned dogs with cranial cruciate ligament rupture. Methods Dogs were randomly assigned to receive either epidural buprenorphine (4 µg kg?1) or epidural morphine (0.1 mg kg?1) in a total volume of 0.2 mL kg?1. Epidural injections were performed immediately after induction of anesthesia. End‐tidal halothane and CO2 were recorded every 15 minutes from the time of epidural administration of drug to extubation. A numerical rating pain score system was used by a blinded observer to evaluate analgesia beginning at extubation and continuing at specific intervals for 24 hours after surgery. Heart rate, respiratory rate, and blood pressure were recorded noninvasively at the same times. If pain score indicated moderate discomfort, rescue morphine at 1.0 mg kg?1 was administered intramuscularly. Results There were no significant differences between groups with respect to pain score, heart rate, respiratory rate, indirect blood pressure, end‐tidal halothane or end‐tidal CO2 at any time point. Fifty percent of dogs in the buprenorphine group and 50% of dogs in the morphine group required rescue analgesic medication. Time of systemic rescue morphine administration did not differ significantly between the two groups. There were no clinically observable side‐effects from epidural administration of either drug in any of the dogs of this study. Conclusions Epidural buprenorphine is as effective as epidural morphine for the relief of postoperative hindlimb orthopedic pain in dogs. Clinical relevance Buprenorphine appears to be an effective opioid for epidural use in healthy dogs. Buprenorphine may offer certain advantages over morphine for epidural use, such as lower abuse potential and, in some clinics, reduced cost and less wastage of drug. 相似文献
73.
Weisse C Soares N Beal MW Steffey MA Drobatz KJ Henry CJ 《Journal of the American Veterinary Medical Association》2005,226(4):575-579
OBJECTIVE: To determine survival times in dogs with right atrial hemangiosarcoma treated by means of pericardectomy and tumor resection, with or without adjuvant chemotherapy, and identify complications associated with treatment. DESIGN: Retrospective study. ANIMALS: 23 dogs. PROCEDURE: Dogs were included only if the diagnosis was confirmed histologically. RESULTS: The most common initial complaints included acute collapse (8 [35%] dogs), anorexia or inappetence (8 [35%]), and lethargy (8 [35%]). The most common physical examination abnormalities included muffled heart sounds (12 [52%] dogs), tachycardia (7 [30%]), and weak pulses (7 [30%]). Postoperative complications developed in 12 (52%) dogs; however, most complications were minor. Twenty (87%) dogs were discharged from the hospital. Survival time was significantly longer in the 8 dogs that received adjuvant chemotherapy (mean, 164 days; median, 175 days) than in the 15 dogs that did not receive chemotherapy (mean, 46 days; median, 42 days). Dogs that received chemotherapy were significantly younger and had significantly lower WBC counts than did dogs that did not receive chemotherapy. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that in dogs with right atrial hemangiosarcoma, surgical resection of the tumor was associated with a low complication rate and complications that did arise typically were minor. In addition, use of adjuvant chemotherapy following resection was associated with significantly longer survival times, compared with resection alone. 相似文献
74.
Luke Randall Katharina Heinrich Robert Horton Lucy Brunton Matthew Sharman Victoria Bailey-Horne Meenaxi Sharma Ian McLaren Nick Coldham Chris Teale Jeff Jones 《Research in veterinary science》2014
Waste milk samples from 103 farms in England and Wales were examined for the presence of β-lactam antibiotics and ESBL-producing Enterobacteriaceae. Approximately 10 months after the initial sampling, further waste milk, environmental and faecal samples from farms shown to be positive for CTX-M Escherichia coli were investigated further. Isolates with an ESBL phenotype were tested by PCR for the presence of blaCTX-M, blaOXA, blaSHV and blaTEM genes. Isolates positive for blaCTX-M were sequenced to determine CTX-M type. Representative isolates were further examined by PFGE, plasmid replicon typing and serotyping. Of particular interest, 21.4% of waste milk samples contained residues of the cephalosporin cefquinome, which was significantly associated with CTX-M bacteria. Such bacteria occurred in 5.8% of the waste milk samples (including 3.9% CTX-M E. coli). CTX-M types identified were 1, 14, 14b and 15, but none of the E. coli were serotype O25, the serotype of the human pandemic strain. 相似文献
75.
76.
Relationships of dead wood patterns with biophysical characteristics and ownership according to scale in Coastal Oregon,USA 总被引:1,自引:0,他引:1
Dead wood patterns and dynamics vary with biophysical factors, disturbance history, ownership, and management practices; the
relative importance of these factors is poorly understood, especially at landscape to regional scales. This study examined
current dead wood amounts in the Coastal Province of Oregon, USA, at multiple spatial scales. Objectives were to: (1) describe
current regional amounts of several characteristics of dead wood; (2) compare dead wood amounts across ownerships; (3) determine
the relative importance, according to spatial scale, of biophysical and ownership characteristics, to regional dead wood abundance.
Dead wood plot data were evaluated with respect to explanatory variables at four spatial scales of resolution: plots, subwatersheds,
watersheds and subbasins. The relationships of dead wood characteristics with biophysical attributes and ownership were diverse
and scale-specific. Region-wide dead wood abundance and types varied among ownerships, with public lands typically having
higher amounts of dead wood and more large dead wood than private lands. Regression analysis of total dead wood volume indicated
that ownership was important at the subbasin scale. Growing season moisture stress was important at plot, subwatershed, and
watershed scales. Topography was important at the two coarser scales. Multivariate analysis of dead wood gradients showed
that ownership was important at all scales, topography at the subbasin scale, historical vegetation at watershed and subbasin
scales, and current vegetation at plot and subwatershed scales. Management for dead wood and related biodiversity at watershed
to landscape scales should consider the distinct dynamics of snags and logs, the importance of historical effects, and the
relevance of ownership patterns. 相似文献
77.
Donald R. Trout DVM PhD William J. Hornof DVM MS Paul E. Fisher BS 《Veterinary radiology & ultrasound》1991,32(5):251-255
Soft tissue- and bone-phase scintigrams were acquired from 4 normal horses before and over a 14-day period after metacarpophalangeal, antebrachiocarpal, tarsocrural and tarsometatarsal joint blocks. Images were evaluated subjectively and quantitatively for increased activity in these regions. The antebrachiocarpal block resulted in obvious focal accumulation of activity on soft tissue-phase scintigrams. This increased activity was greatest 2 to 4 days postanesthesia and persisted up to 14 days postanesthesia. On quantitative analysis of soft tissue-phase images, similar trends were noted after the metacarpophalangeal and tarsocrural blocks, but these increases were relatively mild and were not evident on subjective evaluation of the images. Abnormal soft tissue-phase activity was not associated with the tarsometatarsal block. On bone-phase scintigrams, increased activity was not present following any of these joint blocks. 相似文献
78.
Effect of sorbitol,single, and multidose activated charcoal administration on carprofen absorption following experimental overdose in dogs 下载免费PDF全文
79.
80.
Gene Stevens Matthew Rhine Zach Straatmann David Dunn 《Communications in Soil Science and Plant Analysis》2016,47(18):2148-2155
Most laboratories make potassium (K) fertilizer recommendations based on field research calibrated with soil K from atomic absorption spectroscopy, flame emission spectroscopy, or inductively coupled plasma mass spectrometry. Information is needed to interpret readings from K+ meters on cotton. The objective was to compare soil and cotton plant sap potassium content from a Laqua Twin? K+ meter to results from standard tests. Aluminum sulfate solution was used with the meter to extract K from 10 soil samples from the North America Proficiency Testing program. A linear relationship (R2 = 0.86) was found between K measured with a K+ meter and K measured with 138 labs using ammonium acetate or Mehlich-3. Using a factor of 1.4754 to adjust readings, fertilizer recommendations with the K+ meter were similar to results from atomic absorption spectroscopy. A linear relationship was found between petiole K measured in the lab and petiole sap measured with the K+ meter. 相似文献