全文获取类型
收费全文 | 4566篇 |
免费 | 233篇 |
国内免费 | 2篇 |
专业分类
林业 | 199篇 |
农学 | 233篇 |
基础科学 | 13篇 |
815篇 | |
综合类 | 358篇 |
农作物 | 694篇 |
水产渔业 | 401篇 |
畜牧兽医 | 1779篇 |
园艺 | 69篇 |
植物保护 | 240篇 |
出版年
2023年 | 29篇 |
2022年 | 88篇 |
2021年 | 163篇 |
2020年 | 97篇 |
2019年 | 121篇 |
2018年 | 144篇 |
2017年 | 134篇 |
2016年 | 146篇 |
2015年 | 150篇 |
2014年 | 205篇 |
2013年 | 269篇 |
2012年 | 328篇 |
2011年 | 383篇 |
2010年 | 220篇 |
2009年 | 199篇 |
2008年 | 292篇 |
2007年 | 296篇 |
2006年 | 263篇 |
2005年 | 218篇 |
2004年 | 214篇 |
2003年 | 186篇 |
2002年 | 140篇 |
2001年 | 131篇 |
2000年 | 92篇 |
1999年 | 57篇 |
1998年 | 28篇 |
1997年 | 17篇 |
1996年 | 9篇 |
1995年 | 9篇 |
1994年 | 3篇 |
1993年 | 8篇 |
1992年 | 16篇 |
1991年 | 14篇 |
1990年 | 22篇 |
1989年 | 17篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1980年 | 5篇 |
1978年 | 11篇 |
1975年 | 3篇 |
1974年 | 5篇 |
1972年 | 5篇 |
1971年 | 3篇 |
1970年 | 3篇 |
1969年 | 3篇 |
1968年 | 4篇 |
排序方式: 共有4801条查询结果,搜索用时 15 毫秒
81.
Avian poxvirus was isolated from nodules on the heads and conjunctiva of two 3-to-4-wk-old ostrich chicks. The ostriches from which poxvirus was isolated had been placed on premises where turkeys that had shown evidence of poxvirus infection had been raised earlier. Microscopically, the nodules from the ostriches were composed of proliferating and hypertrophic epithelial cells that formed large fronds. Most of the hypertrophic epithelial cells contained large eosinophilic intracytoplasmic inclusion bodies characteristic of poxvirus. Characterization of the avian poxvirus isolated from the cutaneous lesions in ostriches was based on western blotting of virus antigen, restriction fragment length polymorphism of genomic DNA, pathogenesis, and cross-protection studies in chickens. Antigenic and genetic studies did not reveal any significant difference between the poxvirus isolated from ostriches (PVO) and fowl poxvirus (FPV). Further, susceptible chickens immunized with the PVO were protected when challenged with a virulent strain of FPV. Thus, the poxvirus isolated from ostriches had similar antigenic, genetic, and biological properties to FPV. 相似文献
82.
Yoo JH Kim MS Park HM 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2006,68(9):967-972
The effect of vasopressin was compared with that of the established vasopressor epinephrine in experimentally induced hemorrhagic shock. After rapid crystalloid resuscitation in a ratio of three volumes of 0.9% saline to one volume of blood (3:1 crystalloid resuscitation), six dogs were given 0.4 IU/kg vasopressin and another six dogs were given 0.1 mg/kg epinephrine. Five dogs in the control group were given fluid resuscitation in the same manner as above without administration of any drugs. Administration of vasopressin increased diastolic arterial pressure (DAP) from 45.0 +/- 4.9 to 91.2 +/- 9.6 mmHg within 5 min, compared with epinephrine from 46 +/- 4.0 to 51.8 +/- 7.7, and control from 47.3 +/- 7.5 to 46.3 +/- 7.3. Systolic arterial pressure (SAP) did not increase significantly following vasopressin compared with epinephrine and control group. Results of DAP and systemic vascular resistance index (SVRI) suggested that vasopressin administration was vasoconstrictive after fluid resuscitation in decompensatory hemorrhagic shock in dogs, whereas epinephrine did not compared with control. In addition, epinephrine did not affect the cardiac index (CI) and SVRI, while a significant decrease in CI and increase in SVRI were observed in vasopressin group. The pressor effect of epinephrine in the vascular system was abrupt and only lasted a short period of time (within 5 min), while that of vasopressin was steady and lasted for more than 1 hr, especially regard to in DAP. When compared with epinephrine, vasopressin can be a more effective and safer choice in patients with severe hemorrhagic shock. 相似文献
83.
Koh PO Kim MO 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2006,68(10):1013-1017
Ethanol exposure is known to suppress male reproductive activity in laboratory animals and humans. The present study was designed to evaluate whether chronic ethanol exposure decreases proliferative activity or increases apoptosis in the testes. Ethanol (1.5 g/kg or 3 g/kg i.p., 15% v/v in saline) was administrated to adult male rats for 10 days. Proliferating cell nuclear antigen (PCNA) was used as a proliferative marker. Western blot analysis showed that ethanol administration significantly reduced the level of PCNA. Also, immunoreactivity of PCNA-positive cells in the spermatogonia and primary spermatocytes were decreased by ethanol exposure. However, the number of TUNEL-positive cells was significantly increased in the testicular germ cells of ethanol-treated rats. Moreover, ethanol administration significantly increased the level of activated caspase-3 in testes. In conclusion, our findings suggest that ethanol may partly contribute to the suppression of male reproductive activity through a reduction of cell proliferation and an enhancement of cell death in rat testes. 相似文献
84.
Yi NY Park SA Jeong MB Kim MS Lim JH Nam TC Seo K 《Journal of the American Animal Hospital Association》2006,42(6):435-439
The medical records of 23 dogs that underwent medial canthoplasty for treatment of epiphora were reviewed. The most prevalent breed encountered was the shih tzu. Other affected breeds included the Pekingese, Maltese, toy poodle, and pug. All dogs had epiphora associated with medial canthal trichiasis and/or entropion. Other ocular abnormalities included conjunctivitis, keratitis, pigmentary keratitis, corneal ulceration, globe prolapse, and nasal fold trichiasis. After medial canthoplasty, the epiphora resolved in all dogs. 相似文献
85.
Mi-Sun Park Yongbaek Kim Min-Soo Kang Sang-Yeon Oh Doo-Youn Cho Nam-Shik Shin Dae-Yong Kim 《Journal of veterinary diagnostic investigation》2006,18(1):130-133
Transmissible venereal tumor (TVT) is a well-documented transplantable tumor in dogs, with no breed or sex predilection and a low metastatic rate. In this report, a 2-year-old intact female Mastiff that had numerous, rapidly growing masses throughout the subcutis mainly at the dorsal body plane, the caudal half of the ventral abdomen, and around the vulva was euthanized due to poor prognosis. Neoplastic nodules similar to those seen in the subcutis were also noted in the lung, anterior mediastinum, liver, spleen, kidney, and superficial and deep lymph nodes in both abdominal and thoracic cavities. The neoplastic nodules from the subcutis as well as metastatic foci revealed similar cytologic and histologic features, which were consistent with canine TVT. By immunohistochemical staining, the neoplastic cells were positive for lysozyme and vimentin but were negative for cytokeratin, desmin, CD3, and CD79a. The diagnosis of the TVT was further supported by the identification and analysis of long interspersed nuclear elements (LINE) from paraffin-embedded tumor tissue. This case is a rare example of TVT with multiorgan metastasis. In this case, the polymerase chain reaction technique was useful in differential diagnosis of canine round cell tumors because this technique can be applied in retrospective as well as future study. 相似文献
86.
Kim YH Kim ES Ko BS Oh SE Ryuk JA Chae SW Lee HW Choi GY Seo DW Lee MY 《Journal of animal science》2012,90(7):2075-2083
This study describes a method for discriminating Rangifer antlers from true Cervus antlers using agarose gel electrophoresis, capillary electrophoresis, quantitative real-time PCR, and allelic discrimination. Specific primers labeled with fluorescent tags were designed to amplify fragments from the mitochondrial D-loop genes for various Cervus subspecies and Rangifer tarandus differentially. A 466-bp fragment that was observed for both Cervus and Rangifer antlers served as a positive control, while a 270-bp fragment was specifically amplified only from Rangifer antlers. Allelic discrimination was used to differentiate between Cervus and Rangifer antlers, based on the amplification of specific alleles for both types of antlers. These PCR-based assays can be used for forensic and quantitative analyses of Cervus and Rangifer antlers in a single step, without having to obtain any sequence information. In addition, multiple PCR-based assays are more accurate and reproducible than a single assay for species-specific analysis and are especially useful in this study for the identification of original Cervus deer products from fraudulent Rangifer antlers. 相似文献
87.
88.
A novel pox virus, condorpox virus (CPV) isolated from the spleen of an Andean condor (Vultur gryphus) by inoculation of chorioallantoic membranes (CAM) of specific pathogen free (SPF) chicken embryos was compared biologically, antigenically and genetically with fowlpox virus (FPV), the type species of the genus Avipoxvirus. Susceptible chickens inoculated with CPV developed only mild localized lesions but were not protected against subsequent challenge with FPV. Based on Western blotting, in addition to the presence of cross-reacting antigens, distinct differences in antigenic profiles of CPV and FPV were observed. Sequence analysis of a 4.5 kb HindIII fragment of CPV genomic DNA revealed the presence of eight co-linear genes corresponding to FPV open reading frame (ORF)193-198, 201 and 203. Interestingly, reticuloendotheliosis virus (REV) sequences present in the genome of all FPV were absent in CPV. Although, the results of a phylogenic analysis suggested that CPV is a member of the genus Avipoxvirus, its unique antigenic, biologic and genetic characteristics distinguish it from FPV to be considered as a new member of this genus. 相似文献
89.
Enteropathogenic Escherichia coli (EPEC) is a major cause of infantile diarrhea in developing countries. However, sporadic outbreaks caused by this microorganism in developed countries are frequently reported recently. As an important zoonotic pathogen, EPEC is being monitored annually in several countries. Hallmark of EPEC infection is formation of attaching and effacing (A/E) lesions on the small intestine. To establish A/E lesions during a gastrointestinal tract (GIT) infeciton, EPEC must thrive in diverse GIT environments. A variety of stress responses by EPEC have been reported. These responses play significant roles in helping E. coli pass through GIT environments and establishing E. coli infection. Stringent response is one of those responses. It is mediated by guanosine tetraphosphate. Interestingly, previous studies have demonstrated that stringent response is a universal virulence regulatory mechanism present in many bacterial pathogens including EPEC. However, biological signficance of a bacterial stringent response in both EPEC and its interaction with the host during a GIT infection is unclear. It needs to be elucidated to broaden our insight to EPEC pathogenesis. In this review, diverse responses, including stringent response, of EPEC during a GIT infection are discussed to provide a new insight into EPEC pathophysiology in the GIT. 相似文献
90.
Mihyun Choi Namsoon Lee Ahyoung Kim Seoyeon Keh Jinsoo Lee Hyunwook Kim Mincheol Choi 《Veterinary radiology & ultrasound》2014,55(1):102-108
Diagnosis of unilateral diaphragmatic paralysis in dogs is currently based on fluoroscopic detection of unequal movement between the crura. Bilateral paralysis may be more difficult to confirm with fluoroscopy because diaphragmatic movement is sometimes produced by compensatory abdominal muscle contractions. The purpose of this study was to develop a new method to evaluate diaphragmatic movement using M‐mode ultrasonography and to describe findings for normal and diaphragmatic paralyzed dogs. Fifty‐five clinically normal dogs and two dogs with diaphragmatic paralysis were recruited. Thoracic radiographs were acquired for all dogs and fluoroscopy studies were also acquired for clinically affected dogs. Two observers independently measured diaphragmatic direction of motion and amplitude of excursion using M‐mode ultrasonography for dogs meeting study inclusion criteria. Eight of the clinically normal dogs were excluded due to abnormal thoracic radiographic findings. For the remaining normal dogs, the lower limit values of diaphragmatic excursion were 2.85–2.98 mm during normal breathing. One dog with bilateral diaphragmatic paralysis showed paradoxical movement of both crura at the end of inspiration. One dog with unilateral diaphragmatic paralysis had diaphragmatic excursion values of 2.00 ± 0.42 mm on the left side and 4.05 ± 1.48 mm on the right side. The difference between left and right diaphragmatic excursion values was 55%. Findings indicated that M‐mode ultrasonography is a relatively simple and objective method for measuring diaphragmatic movement in dogs. Future studies are needed in a larger number of dogs with diaphragmatic paralysis to determine the diagnostic sensitivity of this promising new technique. 相似文献