全文获取类型
收费全文 | 690篇 |
免费 | 64篇 |
专业分类
林业 | 16篇 |
农学 | 8篇 |
基础科学 | 4篇 |
84篇 | |
综合类 | 131篇 |
农作物 | 27篇 |
水产渔业 | 12篇 |
畜牧兽医 | 376篇 |
园艺 | 8篇 |
植物保护 | 88篇 |
出版年
2023年 | 5篇 |
2022年 | 7篇 |
2021年 | 8篇 |
2020年 | 9篇 |
2019年 | 10篇 |
2018年 | 12篇 |
2017年 | 15篇 |
2016年 | 22篇 |
2015年 | 10篇 |
2014年 | 15篇 |
2013年 | 22篇 |
2012年 | 30篇 |
2011年 | 39篇 |
2010年 | 17篇 |
2009年 | 16篇 |
2008年 | 30篇 |
2007年 | 44篇 |
2006年 | 41篇 |
2005年 | 24篇 |
2004年 | 26篇 |
2003年 | 30篇 |
2002年 | 26篇 |
2001年 | 27篇 |
2000年 | 28篇 |
1999年 | 12篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1992年 | 5篇 |
1991年 | 11篇 |
1990年 | 10篇 |
1989年 | 15篇 |
1988年 | 12篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1980年 | 5篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1974年 | 4篇 |
1972年 | 6篇 |
1971年 | 7篇 |
1970年 | 4篇 |
1969年 | 6篇 |
1967年 | 5篇 |
1966年 | 4篇 |
1963年 | 4篇 |
1955年 | 4篇 |
1917年 | 3篇 |
排序方式: 共有754条查询结果,搜索用时 31 毫秒
81.
Cockroach control in sewers in Singapore using bioresmethrin and piperonyl butoxide as a thermal fog
Cockroaches have considerable importance as vectors of disease. In tropical areas, large populations of Periplaneta americana may be found in sewers and the refuse chutes of large apartment blocks. These cockroach populations are not accessible to residual insecticide treatment with sprays but may be controlled with thermal fogs of pyrethroids. An experiment on the use of bioresmethrin (5-benzyI-3-furyimethyl-(+)-trans chrysanthemate) as 0.15% and 0.25% w/v solutions with equal amounts of synergist in kerosene discharged from a TIFA fog generator was made at Toa Payoh in Singapore. Effective control was obtained with 0.15% bioresmethrin plus 0.55% piperonyl butoxide in kerosene blown into the sewers and waste chutes initially, at four weeks, at eight weeks later and then followed by treatment every two months. 相似文献
82.
83.
: Changes in legislation that facilitate movement of companion animals within the European Union will expose those animals to microbial and parasitic organisms currently exotic to Ireland. This paper reviewed information on the exotic diseases most likely to be introduced to Ireland by travelling dogs and cats: rabies, leishmaniosis, babesiosis, ehrlichiosis, anaplasmosis and dirofilariosis. 相似文献
84.
Five trials were conducted to evaluate the effects of the presence of horns on cattle on carcase bruising. In each trial there were three groups of cattle, hornless, horned and mixed (some with hrons and some without). The weight of bruised tissue trimmed from the carcases of the cattle in the horned groups was significantly greater than that trimmed from the carcases of the cattle in the hornless groups. When horned and hornless cattle are mixed the hornless animals in the mixed group sustain significantly more bruising than animals in a group consisting soley of hornless animals while the horned animals in a mixed group have a similar degree of bruising to cattle in a group consisting solely of horned cattle. 相似文献
85.
Boysen SR Rozanski EA Tidwell AS Holm JL Shaw SP Rush JE 《Journal of the American Veterinary Medical Association》2004,225(8):1198-1204
OBJECTIVE: To establish a focused assessment with sonography for trauma (FAST) protocol in dogs, determine whether FAST can be performed by veterinary clinicians without extensive ultrasonographic experience, and assess the frequency of free fluid (as determined via FAST) in the abdominal cavity of dogs following motor vehicle accidents (MVAs). DESIGN: Prospective study. ANIMALS: 100 client-owned dogs evaluated within 24 hours of an MVA. PROCEDURE: Dogs were placed in lateral recumbency for the FAST examination. To detect fluid in the abdomen, 2 ultrasonographic views (transverse and longitudinal) were obtained at each of 4 sites (just caudal to the xiphoid process, on the midline over the urinary bladder, and at the left and right flank regions). RESULTS: In the 100 dogs evaluated via FAST, free abdominal fluid was detected in 45 dogs. In 40 of those 45 dogs, abdominocentesis was performed; hemoperitoneum and uroperitoneum were diagnosed in 38 and 2 dogs, respectively. Compared with dogs that had no free abdominal fluid detected via FAST, dogs that had free abdominal fluid detected via FAST had significantly higher heart rates and serum lactate concentrations and significantly lower PCVs and total solid concentrations. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that FAST is a simple and rapid technique that can be performed on dogs in an emergency setting to detect intra-abdominal free fluid and can be performed by veterinary clinicians with minimal previous ultrasonographic experience. 相似文献
86.
Malik R Shaw SE Griffin C Stanley B Burrows AK Bryden SL Titmarsh J Stutsel MJ Carter SA Warner A Martin P Wigney DI Gilpin C 《The Journal of small animal practice》2004,45(10):485-494
Nine dogs with panniculitis due to rapidly growing mycobacteria (RGM) were examined over 17 years. Dogs were two to 15 years; five were male, four were female. All were obese or in good condition. Antecedent injury, typically a dog bite or vehicular trauma, could be identified in some patients, while one bitch had hyperadrenocorticism. Infections involved different locations, although the cervicothoracic region, dorsum or flank were most often affected. Patients were systemically well, apart from one dog with pyrexia and two with pain or lameness. Cytology demonstrated pyogranulomatous inflammation, but in only one case was it possible to see acid-fast bacilli (AFB) in smears. Histology demonstrated chronic active pyogranulomatous panniculitis and dermatitis; AFB could be detected in only four specimens. Culture of aspirates or resected tissues demonstrated RGM in all cases, comprising six Mycobacterium smegmatis group and three Mycobacterium fortuitum group isolates. Resection of infected tissues, perioperative injectable antimicrobials and long courses of oral antimicrobials chosen according to susceptibility data generally effected a cure, although some cases recurred. 相似文献
87.
Shaw DT Rozeboom DW Hill GM Orth MW Rosenstein DS Link JE 《Journal of animal science》2006,84(5):1138-1146
The objective of this study was to determine if supplement withdrawal (omission of dietary vitamin and trace mineral premixes and 2/3 of inorganic P) 28-d preslaughter and the feeding of wheat middlings (dietary concentrations of 5, 15, or 30% from weaning to 16 kg, 16 to 28 kg, and 28 kg to slaughter, respectively) affect bone metabolism, bone strength, bone density, and the incidence of bone fractures at slaughter in pigs. Crossbred barrows (n = 64) were assigned to a 2 x 2 factorial arrangement of treatments (with or without supplement withdrawal, and with or without wheat middlings). Serum was collected on d 0, 14, and 27 of the preslaughter withdrawal period to determine changes in the concentrations of osteocalcin, an indicator of bone formation, and pyridinoline, an indicator of bone resorption. The serum osteocalcin and pyridinoline concentrations on d 14 and 27 were analyzed as change from the d-0 concentration. At slaughter, radiographs of the lumbar vertebrae and of the right and left femurs were taken to determine the incidence of bone fractures. Third metacarpal bones were analyzed for bone mineral density, peak load, ultimate shear stress, and percent ash. Supplement withdrawal increased (P < 0.05) serum osteocalcin and pyridinoline concentrations, indicating an increase in osteoblast activity and bone resorption. Supplement withdrawal decreased (P < 0.01) bone mineral density, peak load, ultimate shear stress, and percent ash of the metacarpal bones. Dietary wheat middling inclusion did not alter bone quality. Neither supplement withdrawal nor wheat middling inclusion affected the incidence of bone fractures at slaughter. The results of this study indicate that removing inorganic P, vitamin premix, and trace mineral premix for 28 d preslaughter increases bone turnover and decreases bone quality. 相似文献
88.
A trehalose synthase (TSase) gene from a hyperacidophilic, thermophilic archaea, Picrophilus torridus, was synthesized using overlap extension PCR and transformed into Escherichia coli for expression. The purified recombinant P. torridus TSase (PTTS) showed an optimum pH and temperature of 6.0 and 45 degrees C, respectively, and the enzyme maintained high activity at pH 5.0 and 60 degrees C. Kinetic analysis showed that the enzyme has a 2.5-fold higher catalytic efficiency (k(cat)/K(M)) for maltose than for trehalose, indicating maltose as the preferred substrate. The maximum conversion rate of maltose into trehalose by the enzyme was independent of the substrate concentration, tended to increase at lower temperatures, and reached approximately 71% at 20 degrees C. Enzyme activity was inhibited by Hg2+, Al3+, and SDS. Five amino acid residues that are important for alpha-amylase family enzyme catalysis were shown to be conserved in PTTS (Asp203, Glu245, Asp311, His106, and His310) and required for its activity, suggesting this enzyme might employ a similar hydrolysis mechanism. 相似文献
89.
90.
Ferris NP King DP Reid SM Hutchings GH Shaw AE Paton DJ Goris N Haas B Hoffmann B Brocchi E Bugnetti M Dekker A De Clercq K 《Veterinary microbiology》2006,117(2-4):130-140
Five European reference laboratories participated in an exercise to evaluate the sensitivity and specificity of their routinely employed RT-PCR tests and cell cultures for the detection and isolation of foot-and-mouth disease (FMD) virus. Five identical sets of 20 coded samples were prepared from 10 vesicular epithelia, which were derived from submissions from suspect cases of FMD or swine vesicular disease (SVD). Sixteen samples were derived from six FMD virus positive epithelia representing four different serotypes (two each of types O and A and one each of types Asia 1 and SAT 2), two from samples which had been found to be negative by antigen ELISA and virus isolation (VI) in cell culture and two from SVD virus positive epithelia. Some of the FMD virus positive samples were prepared from 10-fold serial dilutions of three of the initial suspensions. Each laboratory tested the samples by one or more of its available RT-PCR procedures and inoculated cell cultures that it routinely uses for FMD diagnosis in attempts to isolate virus, the specificity of which was confirmed by antigen ELISA. The best of the RT-PCR assays used in each laboratory gave comparable results while the sensitivity of cell cultures was variable from high in one laboratory, moderate in two and low in two others. This prototype panel of samples would appear suitable for external quality assurance of these tests but would benefit from the inclusion of more negative samples and an extension in the serial dilution range of one or more of the FMD positive sample titration series. 相似文献