全文获取类型
收费全文 | 2602篇 |
免费 | 207篇 |
国内免费 | 178篇 |
专业分类
林业 | 212篇 |
农学 | 127篇 |
基础科学 | 92篇 |
163篇 | |
综合类 | 1116篇 |
农作物 | 148篇 |
水产渔业 | 98篇 |
畜牧兽医 | 596篇 |
园艺 | 160篇 |
植物保护 | 275篇 |
出版年
2024年 | 10篇 |
2023年 | 56篇 |
2022年 | 60篇 |
2021年 | 127篇 |
2020年 | 109篇 |
2019年 | 129篇 |
2018年 | 69篇 |
2017年 | 79篇 |
2016年 | 144篇 |
2015年 | 85篇 |
2014年 | 169篇 |
2013年 | 164篇 |
2012年 | 205篇 |
2011年 | 199篇 |
2010年 | 124篇 |
2009年 | 149篇 |
2008年 | 107篇 |
2007年 | 113篇 |
2006年 | 105篇 |
2005年 | 99篇 |
2004年 | 76篇 |
2003年 | 62篇 |
2002年 | 46篇 |
2001年 | 55篇 |
2000年 | 49篇 |
1999年 | 63篇 |
1998年 | 55篇 |
1997年 | 35篇 |
1996年 | 27篇 |
1995年 | 34篇 |
1994年 | 27篇 |
1993年 | 21篇 |
1992年 | 20篇 |
1991年 | 18篇 |
1990年 | 20篇 |
1989年 | 20篇 |
1988年 | 13篇 |
1987年 | 16篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1955年 | 2篇 |
排序方式: 共有2987条查询结果,搜索用时 15 毫秒
991.
The protein of BRCC36 is a kind of enzyme specifically hydrolyzing K63-linked poly-ubiquitin chain and widely found in a variety of eukaryotic cells. BRCC36 recognizes diverse substrate proteins, and participates in various kinds of pathophysiological responses such as DNA damage repair, cell signal transduction and cell cycle control. It plays an important role in the process of cancer, angiogenesis and cardiac injury. This review discusses the progress in the investigation on BRCC36 protein to provide the necessary information for searching new therapeutic targets of many diseases. 相似文献
992.
Ryo D. Obara Yuki Kato Yoshiji Asaoka Miho Mukai Keigo Matsuyama Kae Fujisawa Minako Tajiri Tamio Fukushima Mikinori Torii 《Journal of toxicologic pathology》2021,34(3):261
A 6-month-old female beagle dog, assigned to the low-dose group in a toxicity study, was evaluated for compound toxicity, and spontaneous hyperadrenocorticism was suspected. The animal had an externally apparent distended abdomen on clinical examination upon arrival. Pre-dose clinical pathology showed slightly higher erythroid parameters and stress leukogram on hematology; plasma biochemistry showed higher total protein, gamma-glutamyl transferase, total cholesterol, and triglyceride levels than the reference data. On necropsy, a prominent increase in adipose tissues of the subcutis and abdomen and increased weight of the adrenal gland and liver were observed. Histopathology revealed diffuse hyperplasia of adrenocortical cells in the zona fasciculata and reticularis, cortical atrophy of the thymus, and abundant glycogen accumulation in the hepatocytes. These findings were incidental and not test-substance-related. Electron microscopy of the adrenocortical cells in the zona fasciculata revealed decreased typical translucent lipid droplets, increased electron-dense lipid droplets, and abundant smooth endoplasmic reticulum and lysosomes. Additionally, increased numbers of various sizes and forms of mitochondria with tubular, vesicular, or lamellar cristae compared to that of normal animals were observed. These ultrastructural characteristics of the adrenocortical cells suggested hyperfunction. The pre-dose plasma cortisol levels were slightly higher than those of other females assigned to the toxicity study, while plasma adrenocorticotropic hormone levels were within the normal range. These findings indicate that hyperadrenocorticism is a possible cause of the systemic changes in this case. 相似文献
993.
Diversity in the urban forest is important as it reduces risks from pests and diseases and from climate change and improves resilience in the supply of ecosystem services. To manage and improve diversity, there has been wide-spread acceptance of the 10/20/30 ‘rule of thumb’ proposed by Santamour, which states that municipal forests should comprise no more than 10% of any particular species, 20% of any one genus or 30% of any single family. While the implementation of targets based on Santamour's rule has contributed to a more diverse and resilient urban forest in many cities, there has been little empirical investigation of actual patterns of diversity occurring globally in different climates and land uses. In this study, we explored diversity and the relative abundance of the most common species, genus and family in 151 urban forest inventories from 108 different cities around the world. Observed patterns showed that relative abundance of the most common taxon was a good predictor of diversity and could be a useful measure of diversity for urban forest managers. Relative abundance of the most common taxon was much higher than the proposed benchmark at the species level, but comparable with proposed benchmarks at the genus and family level. Patterns varied by both climate and land use. Diversity was consistently lower in Continental climates and in streetscapes, and higher in Temperate climates and in urban forests that spanned multiple land uses. Further considerations in setting diversity benchmarks are discussed. 相似文献
994.
杨树是国营新民市机械林场主要造林树种,因大面积营造用材林,树种单一,植被种类少,杨树病虫害发病率较高,文章针对国营新民市林场杨树速生丰产林主要病虫害的防治成功经验,将主要病虫害的防治技术作一总结,以供从事杨树营林工作的技术人员参考。 相似文献
995.
996.
摘要:施用3种药剂防治樟子松细菌性病害,三种药剂对病害有不同效果,其中500倍30%代森锰锌与500倍70%敌磺钠可溶性粉剂防治效果均达90%以上,硫酸亚铁防病效果较好,且持效期长,试验对樟子松大田播种育苗具有指导意义。 相似文献
997.
998.
F. H. M. Borgsteede 《The Veterinary quarterly》2013,33(4):181-188
Summary The activity of albendazole against gastrointestinal helminths in naturally infected calves in the Netherlands was tested. The calves were in their fist grazing season and kept in two groups of ten. One of these groups was grazed alternately with sheep. Five out of each group were drenched with albendazole (7.5 mg/kg) on the day they were housed (November 1). Before and 2, 14, and 28 days after treatment individual faecal samples were taken from all calves and larval cultures were made. Ten calves, six treated and four untreated, were killed for post mortem studies 14 days after treatment The remaining calves were slaughtered 14 days later. The drug was highly effective in reducing the egg output, measured as the number of larvae cultured per gram of faeces. Compared with the untreated calves, the reduction was more than 99% two days after treatment, 100% at 14 days, and 99% after 28 days. It was shown that egg output 28 days after treatment came from worms which had developed from arrested larvae of Ostertagia ostertagi that had survived treatment. Post mortem results showed an efficacy of 100% against adult O. ostertagi, of almost 100% against Trichostrongylus axei, and 100% against adult and larval Cooperia oncophora. Twenty‐eight days after treatment, the reduction of arrested early fourth stages of O. ostertagi was 85% in comparison with the untreated calves. Apparently less effect was found against Trichuris ovis at the given dose rate. 相似文献
999.
C. D. W. König 《The Veterinary quarterly》2013,33(3):127-130
The occurrence of keratoconjunctivitis infectiosa ovis (KIO) in the Netherlands was reported by Holland et al. in 1969 for the first time. At present the disease is well known in the Netherlands. Nevertheless there are still questions about the causative agent and the most effective and easiest therapy. Most authors suppose that the disease is caused by Colesiota conjunctivae, although others mention infections by other chlamydia, Mycoplasma conjunctivae, Mycoplasma ovipneumoniae, Acholeplasma oculi and a wide variety of bacteria. The diagnosis can be made on the basis of the symtoms and the detection of the agent in Conjunctival scrapings. The bacilliform bodies can be found in conjunctival smears in the cytoplasm (Giemsa, Stamp). Many therapies are used topically, parenterally or orally. Locally used eye‐ointments must be effective against Colesiota; antimicrobial drugs administered by injection must be effective against the latter and also provide a sufficient cell tissue penetration with excretion into the lacrimal fluid. Injections have proved to be easier to administer, especially in serious outbreaks, but such outbreaks are exceptional (18). Some therapies have been evaluated in small scale experiments (28) as well as in field trials (17). 相似文献
1000.
Summary Both clinical and pathological features of seven horses suffering from a squamous cell carcinoma of the stomach are presented. The main complaints in the horses, aged six years or more, were loss both of weight and of condition. Metastases had often developed. The diagnostic difficulties and possibilities are discussed. 相似文献