全文获取类型
收费全文 | 2325篇 |
免费 | 29篇 |
国内免费 | 2篇 |
专业分类
林业 | 56篇 |
农学 | 2篇 |
基础科学 | 5篇 |
270篇 | |
综合类 | 862篇 |
农作物 | 49篇 |
水产渔业 | 8篇 |
畜牧兽医 | 1051篇 |
园艺 | 7篇 |
植物保护 | 46篇 |
出版年
2012年 | 137篇 |
2011年 | 175篇 |
2010年 | 26篇 |
2009年 | 20篇 |
2008年 | 152篇 |
2007年 | 150篇 |
2006年 | 128篇 |
2005年 | 124篇 |
2004年 | 108篇 |
2003年 | 122篇 |
2002年 | 121篇 |
2001年 | 81篇 |
2000年 | 104篇 |
1999年 | 41篇 |
1998年 | 9篇 |
1996年 | 10篇 |
1995年 | 12篇 |
1994年 | 21篇 |
1993年 | 16篇 |
1992年 | 12篇 |
1991年 | 31篇 |
1990年 | 9篇 |
1989年 | 17篇 |
1988年 | 12篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 13篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1979年 | 18篇 |
1978年 | 11篇 |
1977年 | 12篇 |
1974年 | 15篇 |
1973年 | 10篇 |
1971年 | 10篇 |
1970年 | 18篇 |
1969年 | 16篇 |
1967年 | 11篇 |
1963年 | 15篇 |
1959年 | 14篇 |
1958年 | 34篇 |
1957年 | 16篇 |
1956年 | 18篇 |
1955年 | 17篇 |
1954年 | 22篇 |
1953年 | 13篇 |
1948年 | 12篇 |
1945年 | 11篇 |
1943年 | 11篇 |
排序方式: 共有2356条查询结果,搜索用时 15 毫秒
21.
Diversity in tropical rain forests and coral reefs 总被引:18,自引:0,他引:18
Connell JH 《Science (New York, N.Y.)》1978,199(4335):1302-1310
The commonly observed high diversity of trees in tropical rain forests and corals on tropical reefs is a nonequilibrium state which, if not disturbed further, will progress toward a low-diversity equilibrium community. This may not happen if gradual changes in climate favor different species. If equilibrium is reached, a lesser degree of diversity may be sustained by niche diversification or by a compensatory mortality that favors inferior competitors. However, tropical forests and reefs are subject to severe disturbances often enough that equilibrium may never be attained. 相似文献
22.
人力资源外包是企业为降低成本以及提高核心业务竞争力的一种常用的人力资源管理模式。笔者结合工作经验对安徽茶企的现状在人力资源方面的表现进行了简要的分析与介绍,并着重对其中的问题进行详细以及深入的分析,并提出了相应的对策,希望能对相关的管理人员有所启发以及帮助。 相似文献
23.
24.
25.
Immunogenicity and haemagglutination of recombinant Avibacterium paragallinarum HagA 总被引:1,自引:0,他引:1
Inactivated vaccines of Avibacterium paragallinarum provide protection and reduce the economic losses caused by infectious coryza. However, inactivated bacterins provide protection only against the Page serovars included in the vaccine. In this study, we investigated the immunological properties of a functional recombinant haemagglutinin protein (rHagA) derived from a Taiwan isolate strain A9 as the immunogen for vaccination. The rHagA subunit vaccine protected 71% of immunized chickens against 10(10) colony-forming units (CFU) of viable A9. Vaccinated chickens which showed no clinical signs of coryza developed haemagglutination inhibition (HI) titers of 1:10 or greater. Haemagglutination (HA) of serovars A and C was not affected by the presence of rHagA specific antiserum. The HA of rHagA could only be induced against formaldehyde-fixed chicken red blood cells (FA-RBCs). These results suggested that HagA is a moderate immunogen and might not be a major haemagglutinin in vivo. However, HagA might be involved in haemagglutination when treated serovar C aggregates fixed RBCs in vitro. 相似文献
26.
Taeymans O Peremans K Saunders JH 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2007,21(4):673-684
This review describes the advantages and disadvantages of radiography, ultrasonography, and nuclear medicine in the 2 most frequent thyroid pathologies of the dog: acquired primary hypothyroidism and thyroid neoplasia. Ultrasonography and scintigraphy remain the 2 most indicated imaging modalities for these thyroid abnormalities. However, as in human medicine, computed tomography and magnetic resonance imaging also have potential indications. This is especially the case in the evaluation of the extent, local invasiveness, and local or distant metastases of thyroid neoplasia. Based on experience with different imaging modalities in people, we suggest future directions in the imaging of the canine thyroid gland. 相似文献
27.
Kim MS Yoo JH Seo KM Jeong SM 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2007,69(11):1163-1165
The effects of electroacupuncture (EA) on intraocular pressure (IOP) and hemodynamic parameters were evaluated in isoflurane anesthetized 10 (5 males, 5 females) normal mongrel dogs (8.1-9.8 kg, 6-8 years old). After determination of baseline IOP and hemodynamic parameters (cardiac index, systolic arterial pressure, diastolic arterial pressure, heart rate and systemic vascular resistance index), EA was applied at 3 acupoints (LI-4, LIV-3 and GB-37) for 20 min. After the EA treatment, IOP was significantly decreased in the both eyes (p<0.05). However, there were not significant differences in hemodynamic parameters between those of before and after EA treatment. From these results, the EA treatment at LI-4, LIV-3 and GB-37 would be considered one of the valuable methods for the IOP treatment in dogs. 相似文献
28.
Shin JH Sakoda Y Kim JH Ochiai K Umemura T 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2007,69(11):1167-1169
Rabbits were immunized with inactivated influenza virus via the subarachnoidal (SA) or subcutaneous (SC) route, and the antibody titers in cerebrospinal fluid (CSF) and serum were assayed. There were no nervous signs or morphological lesions related to SA immunization. In the SC group, the antibody titer was elevated in serum, but not elevated in CSF. In the SA group, the antibody titer was significantly elevated in serum and even in CSF, and their antibody titers were much greater than in the SC group. The present results suggest that intrathecal immunization is more effective than SC immunization at inducing a protective immune response against the transneural spread of viruses. 相似文献
29.
30.
Park C Yoo JH Jeon HW Kang BT Kim JH Jung DI Lim CY Lee HJ Hahm DH Woo EJ Park HM 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2007,69(9):951-955
Three dogs were presented to us for evaluation of cardiac problems. Electrocardiographic recordings revealed severe tachyarrhythmia and atrial fibrillation with ventricular tachycardia in 2 of the 3 dogs. The echocardiographic findings of the 3 dogs revealed markedly decreased fractional shortening and a marked increase in E-point septal separation. Based on the results of electrocardiographic and echocardiographic evaluation, the 3 dogs were diagnosed as dilated cardiomyopathy (DCM). The dogs were treated with conventional cardiac medication, but cardiac function did not improve and the clinical signs remained. We subsequently attempted treatment with granulocyte-colony stimulating factor (G-CSF; 10 microg/kg, subcutaneously). The specific purpose of G-CSF therapy for DCM was to improve cardiac function and a significant improvement in cardiac function was confirmed. The three dogs had no treatment side effects. This case report suggests that G-CSF might have therapeutic effects for medically refractory DCM in dogs. 相似文献