全文获取类型
收费全文 | 2225篇 |
免费 | 102篇 |
专业分类
林业 | 355篇 |
农学 | 61篇 |
基础科学 | 8篇 |
325篇 | |
综合类 | 252篇 |
农作物 | 43篇 |
水产渔业 | 124篇 |
畜牧兽医 | 1004篇 |
园艺 | 33篇 |
植物保护 | 122篇 |
出版年
2022年 | 19篇 |
2021年 | 33篇 |
2020年 | 25篇 |
2019年 | 27篇 |
2018年 | 46篇 |
2017年 | 42篇 |
2016年 | 46篇 |
2015年 | 40篇 |
2014年 | 47篇 |
2013年 | 101篇 |
2012年 | 101篇 |
2011年 | 114篇 |
2010年 | 43篇 |
2009年 | 64篇 |
2008年 | 92篇 |
2007年 | 103篇 |
2006年 | 97篇 |
2005年 | 87篇 |
2004年 | 74篇 |
2003年 | 68篇 |
2002年 | 58篇 |
2001年 | 44篇 |
2000年 | 50篇 |
1999年 | 40篇 |
1998年 | 16篇 |
1997年 | 14篇 |
1995年 | 17篇 |
1993年 | 14篇 |
1992年 | 31篇 |
1991年 | 35篇 |
1990年 | 26篇 |
1989年 | 35篇 |
1988年 | 18篇 |
1987年 | 21篇 |
1986年 | 33篇 |
1985年 | 23篇 |
1984年 | 26篇 |
1983年 | 17篇 |
1980年 | 16篇 |
1979年 | 34篇 |
1978年 | 18篇 |
1976年 | 15篇 |
1974年 | 15篇 |
1973年 | 20篇 |
1972年 | 30篇 |
1971年 | 23篇 |
1970年 | 24篇 |
1969年 | 17篇 |
1967年 | 14篇 |
1965年 | 13篇 |
排序方式: 共有2327条查询结果,搜索用时 31 毫秒
81.
Prognostic significance of serum alkaline phosphatase activity in canine appendicular osteosarcoma 总被引:3,自引:0,他引:3
Garzotto CK Berg J Hoffmann WE Rand WM 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2000,14(6):587-592
Sixty-one dogs with appendicular osteosarcoma were treated with amputation and chemotherapy of cisplatin and doxorubicin. Serum samples were obtained before and after treatment for determination of total alkaline phosphatase (TALP) activity as well as the activities of the constituent bone (BALP), liver (LALP), and corticosteroid-induced (CALP) isoenzymes. The relationship between alkaline phosphatase activities and survival was examined by Cox proportional hazards regression analysis and Kaplan-Meier log rank analysis. Mean activity of TALP, BALP, and LALP decreased significantly after treatment (P < .001). TALP and LALP activities before treatment were significantly correlated with survival (P = .006 and .001, respectively). The correlation between BALP activity before treatment and survival approached significance (P = .054). CALP activity and TALP, BALP, and LALP activities after treatment were not significantly correlated with survival. Dogs with normal pretreatment TALP and BALP activities survived significantly longer than dogs with increased pretreatment activities (P = .001 and .003, respectively). Median survival times for dogs with normal or increased TALP activities before treatment were 12.5 and 5.5 months, respectively; and median survival times for dogs with normal or increased BALP activities before treatment were 16.6 and 9.5 months, respectively. In the design of future clinical trials involving dogs with osteosarcoma, consideration should be given to stratifying the randomization according to alkaline phosphatase activity. In addition, alkaline phosphatase activity should be a factor considered by clinicians attempting to tailor the aggressiveness of adjuvant chemotherapy to the needs of individual patients or owners. 相似文献
82.
von Rechenberg B McIlwraith CW Akens MK Frisbie DD Leutenegger C Auer JA 《Equine veterinary journal》2000,32(2):140-150
Nitric oxide (NO), prostaglandin E2 (PGE2), and the activity of neutral metalloproteinases (NMPs) were measured in conditioned media of equine synovial membrane and articular cartilage explant cultures from horses with normal joints (n = 7) and from horses affected with moderate (n = 7) or severe osteoarthritis (n = 14) as judged by macroscopic appearance. Normal articular cartilage appeared glossy and bluish-white, was of normal thickness and showed no evidence of discolouration, fibrillation or other cartilage discontinuity. Slight discolouration and fibrillation or minor clefts of the cartilage were considered as moderate OA, whereas erosions of articular cartilage down to the subchondral bone were considered as cases of severe OA. Explant cultures of equine synovial membrane and articular cartilage released the local mediators, NO and PGE2, as well as detectable levels of NMP activity into culture media. Concentrations of NO were higher in articular cartilage explants compared to synovial membrane explants, whereas concentrations of PGE2 were higher in synovial membrane explants. The NMPs with collagenolytic activities were similar in both explant cultures, whereas gelatinolytic activities were higher in synovial membrane explant cultures and caseinolytic activities were generally higher in articular cartilage explant cultures. Furthermore it was shown that concentrations or enzyme activities increased according to the severity of disease of the joints. Concentrations for NO, collagenolytic and gelatinolytic NMPs were relatively stable, whereas PGE2 and caseinolytic NMP concentrations increased over time in culture. 相似文献
83.
Christina von ZallingerDVM Karlheinz TempelDVM 《Veterinary radiology & ultrasound》1998,39(6):495-503
With respect to clinical signs of the radiation syndromes, some remarkable species variations exist. For example the marked delayed reaction of the acute hematologic response in cows. An unusually high sensitivity of the central nervous system is found in burros, which is probably caused by acute vascular and/or metabolic changes in the brain. The species-specific number of intestinal crypt and hemopoietic stem cells may explain the early survival differences among species after high doses of irradiation. Mortality due to acute radiation syndromes is lowest in chickens. Regarding late effects, various neoplasms are typical in dogs, and cattle more commonly develop cataracts. 相似文献
84.
tests, based on the polymerase chain reaction (
), were developed for the detection of two breed-specific mutations responsible for the autosomal recessive disorder bovine α-mannosidosis. The tests involve separate amplification of two exons of the lysosomal α-mannosidase gene followed by restriction enzyme digestion of the amplicons. We demonstrate that one of the mutations, the 662G→A transition, is responsible for α-mannosidosis in Galloway cattle. The other mutation, the 961T→C transition, is uniquely associated with α-mannosidosis in Angus, Murray Grey and Brangus cattle from Australia. The 961T→C mutation was also detected in Red Angus cattle exported from Canada to Australia as embryos. All 39 animals classified as heterozygotes on the basis of biochemical assays were heterozygous for one of the two mutations. None of 102 animals classified as homozygous-normal on the basis of biochemical assays possessed the mutations. Our results indicate that the two breed-specific mutations may have arisen in Scotland and by the export of animals and germplasm disseminated to America, New Zealand and Australia. 相似文献
85.
86.
87.
E Stephan 《DTW. Deutsche tier?rztliche Wochenschrift》1990,97(6):219-220
This paper gives an introduction on the importance of ethology as a basis for the ethical animal welfare. The last edition of the Animal Welfare Act of the Federal Republic of Germany is based on the ethological principle which includes, that the animal must be free to satisfy its needs and preserve itself from damage by using of adequate behavioural patterns. With the help of observing animal behaviour the veterinarian can remark faults in the animal management before pain, suffering or injuries set it. So the importance of the ethology in the system of veterinary education is clear. Pertinent information shall promote the dialogue between scientists working in the field of animal behaviour and people engaged in animal welfare. 相似文献
88.
H. D. von Bonin-Poniß 《Forstwissenschaftliches Centralblatt》1929,51(14):509-521
Ohne Zusammenfassung 相似文献
89.
90.