全文获取类型
收费全文 | 103711篇 |
免费 | 5048篇 |
国内免费 | 63篇 |
专业分类
林业 | 4037篇 |
农学 | 3109篇 |
基础科学 | 633篇 |
11253篇 | |
综合类 | 21414篇 |
农作物 | 3749篇 |
水产渔业 | 4748篇 |
畜牧兽医 | 52861篇 |
园艺 | 1154篇 |
植物保护 | 5864篇 |
出版年
2018年 | 1208篇 |
2017年 | 1290篇 |
2016年 | 1212篇 |
2015年 | 995篇 |
2014年 | 1208篇 |
2013年 | 3402篇 |
2012年 | 2328篇 |
2011年 | 2880篇 |
2010年 | 1940篇 |
2009年 | 1874篇 |
2008年 | 2876篇 |
2007年 | 2751篇 |
2006年 | 2650篇 |
2005年 | 2525篇 |
2004年 | 2506篇 |
2003年 | 2557篇 |
2002年 | 2349篇 |
2001年 | 3150篇 |
2000年 | 3144篇 |
1999年 | 2470篇 |
1998年 | 1008篇 |
1997年 | 973篇 |
1995年 | 1104篇 |
1994年 | 989篇 |
1992年 | 2255篇 |
1991年 | 2356篇 |
1990年 | 2407篇 |
1989年 | 2376篇 |
1988年 | 2237篇 |
1987年 | 2247篇 |
1986年 | 2215篇 |
1985年 | 2162篇 |
1984年 | 1786篇 |
1983年 | 1558篇 |
1982年 | 1050篇 |
1981年 | 996篇 |
1980年 | 950篇 |
1979年 | 1627篇 |
1978年 | 1332篇 |
1977年 | 1177篇 |
1976年 | 1100篇 |
1975年 | 1233篇 |
1974年 | 1543篇 |
1973年 | 1470篇 |
1972年 | 1556篇 |
1971年 | 1422篇 |
1970年 | 1358篇 |
1969年 | 1240篇 |
1968年 | 998篇 |
1967年 | 1145篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
B.W. Parry BVSc PhD B.A. Christie BVSc MACVSc C.C. Gay DVM MVSc FACVSc R.N. Haywood BVSc 《Journal of Equine Veterinary Science》1983,3(1):24-27
A case of acute circulatory failure in a horse is described. The response to intravenous fluid therapy was monitored by measurement of heart and respiratory rates, and arterial and central venous pressures. Heart rate was an unreliable guide to improved circulatory status. Central venous pressure and indirect arterial blood pressure were valuable guides to the efficacy of fluid therapy. 相似文献
952.
In this study, we have determined serum neopterin levels in female dogs with primary malignant mammary tumours. The study involved 50 female dogs which had a malignant mammary tumours removed surgically (32 animals with carcinoma, 12 animals with sarcoma and 6 animals with carcinosarcoma) and 10 clinically healthy female dogs. Serum neopterin levels were determined using a commercial ELISA kit. The mean neopterin levels were lower in the malignant tumour groups than in healthy animals but differences were statistically significant only in carcinoma and sarcoma groups. The decrease of neopterin levels in animals with malignant mammary tumours may suggest their decreased cellular immunity. Moreover, it might indicate that decreased activity of cellular mechanisms of the anti‐neoplastic response is one of the factors associated with the development and course of malignant mammary tumours in female dogs; however, further studies are necessary. 相似文献
953.
OBJECTIVE: This experiment evaluated the perinatal hypoxic effect on the retina of offspring of the ovoviviparous fish. ANIMAL STUDIED: The ovoviviparous fish Xiphophorous maculates was used for the experiment. PROCEDURE: The mothers were kept in a hypoxic environment of 3.5% oxygen for 6 h, starting 30 h before hatching. Subsequently, the retinae of the offspring were fixed, sectioned at 6 microm and evaluated microscopically from the age of 1 to 35 days. RESULTS: Degeneration of the outer nuclear layer of the retina was noted on the 3rd day and severe retinal degeneration was observed on the 35th day. Immunocytochemistry confirmed apoptosis by TUNEL reaction. There was no difference in neovascularization, as revealed by vascular endothelial growth factor, between controls (group 1) and hypoxic fish (group 2). CONCLUSIONS: Perinatal hypoxia could have long-lasting effects on the central nervous system in some species. 相似文献
954.
K. R. Everett I. P. S. Pushparajah O. E. Timudo A. Ah Chee R. W. A. Scheper P. W. Shaw T. M. Spiers J. T. Taylor D. R. Wallis P. N. Wood 《European journal of plant pathology / European Foundation for Plant Pathology》2018,152(2):367-383
Infection of Malus x domestica cv. Royal Gala fruit by Colletotrichum acutatum causing bitter rot was studied in the temperate climate of New Zealand. Temperatures above 15 °C were required for lesions to develop on detached apple wound-inoculated or inoculated without wounding with C. acutatum spores, regardless of maturity. A wetness period of 72 h was required for infection of mature detached apple fruit without wounding. On wound-inoculated detached apple fruits, sporulation was related to temperature and followed a similar pattern. In the field, a mean temperature above 15 °C for 72 h after wound-inoculation was required for lesions to develop. Buds were a more important source of inoculum than twigs, and it was shown that C. acutatum could be isolated more frequently from outer bud scales than from inner scales. Asymptomatic infection of vegetative and reproductive buds was detected. C. acutatum was detected on asymptomic surface-sterilised petals and fruit, more commonly during summer than spring. Symptomless sterilised leaves generally yielded C. acutatum throughout the season, but isolations were more frequent in summer. Recovery of inoculum using a splash meter to detect vertical dispersal showed that in summer inoculum was primarily splashed up from the ground. In spring, inoculum was recovered in similar quantities from all heights up to a metre, suggesting that splash dispersal occurs from the canopy as well as from the ground. A disease cycle for C. acutatum infecting apples and causing bitter rot in New Zealand is suggested. 相似文献
955.
Histological and immunohistochemical evaluation of granulosa cells during different stages of folliculogenesis in bovine ovaries 下载免费PDF全文
APP Teh UZ Izzati K Mori N Fuke T Hirai G Kitahara R Yamaguchi 《Reproduction in domestic animals》2018,53(3):569-581
Bovine granulosa cells (GC) vary in their morphological aspect during different stages of folliculogenesis. In this study, 10 morphologically normal bovine ovaries were collected to study the structural aspects of different stages of GC using intermediate filament protein antibodies including cytokeratin AE1/AE3 (AE1/AE3), vimentin, nectin‐4 and desmin. Hormonal immunolocalization was assessed using the immunomarkers anti‐Müllerian hormone (AMH) and inhibin alpha. In addition, tumour markers and proliferation markers using c‐erbB‐2 oncoprotein and proliferating cell nuclear antigen, respectively, were investigated. The immunolabelling of AE1/AE3 in GC was strongest in the early follicle stage and gradually decreased when reaching the Graafian follicle stage. Its immunolabelling increased again as the stage progressed from stage I to stage III. The immunolabelling of inhibin alpha was inversely proportional to that of AE1/AE3 in the developing ovarian follicles as their immunolabelling is opposite to each other during folliculogenesis. AMH was immunopositive in almost all GC stages in different intensities and percentages, except for some negative staining in the atretic IV follicles. The atretic IV follicle is a unique type of atretic follicle that shows Call‐Exner body formation, which was mainly found in older cows in this study. The distinct patterns of immunoreactivity for various types of immunomarkers in the different GC stages will play an important role in diagnostic assistance of various follicle conditions, including cystic ovaries and GC tumours. 相似文献
956.
Comparative effects of mu and kappa opiate agonists on the cecocolic motility in the pony. 下载免费PDF全文
The electrical and mechanical activity of the large intestine and its response to administration of opiate mu and kappa agonists were assessed from electrodes and inductograph coils chronically implanted on the cecocolic segment in six ponies given a diet of hay and concentrates. Before the drugs were given, migrating complexes propagating from the cecum into the colon occurred at the rate of 1.5 to 16/hour. During this propulsive activity, the cecocolic sphincter opened and closed allowing the outflow of cecal contents and preventing the backflow of colic contents. Each pony was used as its own control and was given fentanyl (0.01 and 0.05 mg/kg of body weight, IV) and U50488H (0.1 and 0.5 mg/kg, IV) at weekly intervals. The mu agonist fentanyl elicited a marked phase of inhibition of the propulsive activity and a closure of the cecocolic sphincter that lasted one to two hours depending on the dose. The kappa agonist U50488H induced an inhibition of the short spiking activity, i.e. of the resting muscle tone. It did not disturb the occurrence of migrating complexes nor that of the openings of the cecocolic sphincter. These kappa compounds may be drugs of choice to alleviate visceral pain in colic stases without inducing delay of transit unlike mu compounds. 相似文献
957.
Ohne ZusammenfassungÜberarbeiteter Teil einer Ingenieur-Abschlußarbeit an der Staatlichen Ingenieurschule für Holztechnik in Rosenheim des letztgenannten Verfassers. 相似文献
958.
Couacy-Hymann E Bodjo SC Danho T Koffi MY Libeau G Diallo A 《Preventive veterinary medicine》2007,78(1):85-88
We observed 15 goats for 9 days after subcutaneous infection with 10(3) TCID(50) with isolates of peste-des-petits ruminants virus from Africa and India and five concurrent, uninfected control goats. Typical clinical signs of the infection were present in all 15 infected goats by day 8 and in most by day 6 and some signs were present by day 4. However, 6 out of 15 goats already have detectable virus shedding by day 3 and four more were shedding by day 4 and every goat had virus shedding for at least 1 day before the recognition of clinical signs. This experiment indicates that incubatory carriers therefore might play a role in the transmission of PPRV among small ruminants. 相似文献
959.
960.
Stein T Martineau GP Morris R Charette R 《The Canadian veterinary journal. La revue veterinaire canadienne》1987,28(6):355-362
It is proposed that just as the stethoscope and thermometer are fundamental tools for individual medicine, production and health recording systems are fundamental tools for effective population medicine. Treatment and control of clinical diseases as the primary objective is no longer considered appropriate for livestock population. Disease in populations now describes a deviation between what is happening and what is expected to happen. This redefinition of disease implies that it is of multifactorial origin and thus a different problem solving approach must be implemented. Therefore, a swine enterprise must be considered as a system, a set of interdependent components continuously interacting to produce pork. As a system, it is characterized by certain properties: change, environment, counterintuitive behavior, drift to low performance, interdependency, and organization. A redefinition of diseases implies also that they are not only “treated” but managed. Management consists of planning, monitoring, evaluation, and analysis. For this process to be implemented successfully, a goal-directed recording system providing a farm-based infrastructure for problem solving is essential. Clinical problem solving (diagnosis) is thus based on epidemiological and demographic methods. 相似文献