全文获取类型
收费全文 | 126719篇 |
免费 | 6736篇 |
国内免费 | 128篇 |
专业分类
林业 | 5860篇 |
农学 | 3990篇 |
基础科学 | 763篇 |
14995篇 | |
综合类 | 20749篇 |
农作物 | 4855篇 |
水产渔业 | 6137篇 |
畜牧兽医 | 67527篇 |
园艺 | 1479篇 |
植物保护 | 7228篇 |
出版年
2018年 | 1820篇 |
2017年 | 2019篇 |
2016年 | 1851篇 |
2015年 | 1592篇 |
2014年 | 1983篇 |
2013年 | 4603篇 |
2012年 | 3513篇 |
2011年 | 4324篇 |
2010年 | 2796篇 |
2009年 | 2813篇 |
2008年 | 4202篇 |
2007年 | 4012篇 |
2006年 | 3835篇 |
2005年 | 3585篇 |
2004年 | 3432篇 |
2003年 | 3442篇 |
2002年 | 3175篇 |
2001年 | 4217篇 |
2000年 | 4143篇 |
1999年 | 3250篇 |
1998年 | 1282篇 |
1997年 | 1251篇 |
1996年 | 1203篇 |
1995年 | 1377篇 |
1994年 | 1154篇 |
1993年 | 1207篇 |
1992年 | 2562篇 |
1991年 | 2825篇 |
1990年 | 2831篇 |
1989年 | 2722篇 |
1988年 | 2464篇 |
1987年 | 2550篇 |
1986年 | 2542篇 |
1985年 | 2425篇 |
1984年 | 1944篇 |
1983年 | 1631篇 |
1982年 | 1155篇 |
1979年 | 1829篇 |
1978年 | 1417篇 |
1977年 | 1159篇 |
1975年 | 1191篇 |
1974年 | 1541篇 |
1973年 | 1536篇 |
1972年 | 1564篇 |
1971年 | 1505篇 |
1970年 | 1489篇 |
1969年 | 1369篇 |
1968年 | 1196篇 |
1967年 | 1224篇 |
1966年 | 1130篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
V Rupasinghe K Iwatsuki-Horimoto S Sugii T Horimoto 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2001,63(6):609-618
A major capsid protein (MCP) gene homologue of porcine cytomegalovirus (PCMV) was identified. Sequence analysis indicated that the PCMV MCP gene is 4,026 nucleotides in length encoding a protein of 1,341 amino acid residues. The predicted molecular weight of the PCMV MCP is 151,456 Da, equivalent to those of other herpesvirus MCP counterparts. Phylogenetic analysis using herpesviral MCP gene sequences confirmed that PCMV is a betaherpesvirus with higher homology with human herpesvirus-6 and -7 than human and mouse cytomegaloviruses. The serum of pig experimentally infected with PCMV did not react with bacterially expressed MCP, suggesting that the PCMV MCP may not be related to the humoral immune response in the course of PCMV infection. Also, we established polymerase chain reaction (PCR) protocols using primers corresponding to MCP gene sequences for detection of PCMV infection. The PCR protocol would be effective for the diagnosis of slow-growing PCMV infection, for which traditional methods involving virus-isolation are not useful. 相似文献
12.
A Chugun T Uchide K Temma R H Kennedy S V Klimberg Y Hara T Sasaki T Akera 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2001,63(12):1315-1322
During the study on the mechanism of doxorubicin-induced cardiotoxicity, we observed that a long incubation (4 hr) with doxorubicin reduced the maximal negative inotropic effects of a muscarinic receptor agonist, carbachol. The mechanism responsible for this doxorubicin-induced reduction of the efficacy of carbachol was examined in isolated guinea pig hearts. In isolated left atrial muscle preparations, 1 hr incubation with 100 microM doxorubicin caused a parallel right-ward shift of the concentration-response curves for carbachol, but a longer (4 hr) incubation with this agent (30, 100 or 200 microM), caused a significant reduction of the magnitude of the negative inotropic effect of carbachol in addition to the concentration-dependent parallel right-ward shift. The 4-hr incubation with these concentrations of doxorubicin also reduced the maximal negative inotropic effect of an adenosine A1 receptor agonist, R-phenylisopropyl adenosine (R-PIA), without affecting the potency of this agonist. Doxorubicin (1 to 100 microM) reduced [3H]quinuclidinyl benzilate (QNB) binding in a concentration dependent manner, but failed to alter [3HIR-PIA binding. The decrease in the magnitude of the maximal negative inotropic effect by doxorubicin was caused by changes in the muscarinic system at steps common to the transduction of muscarinic and adenosine A1 receptor mechanisms. 相似文献
13.
W W Chan K Y Chen H Liu L S Wu J H Lin 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2001,63(10):1057-1062
Since the International Society of Veterinary Acupuncture (IVAS) was founded in 1974, acupuncture (AP) has received greater acceptance by veterinary professionals throughout the world. This article introduces some important animal diseases that respond well to AP therapy. These include resuscitation of small animals, treatment of anoestrous gilts and sows, bovine reproductive disease, canine vertebral problems and equine backpain, etc. Conventional medicine considers these to be difficult cases to treat. Veterinarians have become more aware of the benefits of AP especially for those diseases, thanks to the efforts of experienced practitioners and scientists, and the many published reports on veterinary AP that have introduced some good indications for AP therapy in veterinary practice. Possible mechanisms behind the effectiveness of AP are discussed. This article aims to introduce veterinarians to good indications for AP to initiate their interest in the practice of AP. Although this is a rapidly expanding field, a long march must begin with one step. We wish this article to be the shoes for such a march. For more information on veterinary AP, contact IVAS , P.O. Box 1478, Longmont, CO.. 80502, USA (http://www.ivas.org), or your national veterinary acupuncture society (http://www.komvet.at/ ivadkom/vapsocs.htm). 相似文献
14.
15.
16.
17.
18.
29 samples of commonly used surfaces were tested for their water characteristics (litre weight, water capacity, water binding, water evaporation) and their contribution to airborne fungal spores (dust formation, dust setting). The results are discussed in comparison to the literature with regard to the environment. The results are: 1. Any surface--no matter of what material--eventually causes air pollution with fungal spores and dust. 2. Correct watering prevents air pollution by any surface. 3. Artificial products have no advantage over natural materials in the parameters tested. 4. The question of proper disposal of old surface material has to be clarified before purchase. The results show that a mixture of sand and wood shavings should be recommended as a surface for indoor arenas, especially in regard to environmental protection and proper disposal. 相似文献
19.
Abstract. In field and laboratory experiments the conditioner‘Agri-SC’has shown improvements in the structure of loamy sand soils in east Shropshire, UK. It resulted in statistically significant decreases in soil bulk density values and increases in soil porosity and aggregate stability. Further experiments are in progress on both loamy sand and silt loam soils. 相似文献
20.
Nephrogenic diabetes insipidus is characterized by polyuria, hyposthenuria and compensatory polydipsia. With conventional clinical and laboratory examinations the diagnosis can be established and the differential diagnostic diseases excluded. In order to verify the diagnosis, differentiate the condition from central and nephrogenic diabetes insipidus and rule out psychogenic polydipsia, additional laboratory studies are required: of these, the concentration test, modified Carter-Robbins test and AVP stimulation test are described. 相似文献