全文获取类型
收费全文 | 151432篇 |
免费 | 8470篇 |
国内免费 | 140篇 |
专业分类
林业 | 6427篇 |
农学 | 5065篇 |
基础科学 | 1010篇 |
18011篇 | |
综合类 | 26192篇 |
农作物 | 5919篇 |
水产渔业 | 7533篇 |
畜牧兽医 | 79006篇 |
园艺 | 1862篇 |
植物保护 | 9017篇 |
出版年
2019年 | 1484篇 |
2018年 | 2299篇 |
2017年 | 2648篇 |
2016年 | 2368篇 |
2015年 | 2023篇 |
2014年 | 2542篇 |
2013年 | 5722篇 |
2012年 | 4410篇 |
2011年 | 5462篇 |
2010年 | 3535篇 |
2009年 | 3594篇 |
2008年 | 5341篇 |
2007年 | 4950篇 |
2006年 | 4780篇 |
2005年 | 4246篇 |
2004年 | 4131篇 |
2003年 | 4194篇 |
2002年 | 3817篇 |
2001年 | 5045篇 |
2000年 | 4998篇 |
1999年 | 3849篇 |
1998年 | 1529篇 |
1997年 | 1596篇 |
1996年 | 1427篇 |
1995年 | 1641篇 |
1994年 | 1421篇 |
1993年 | 1481篇 |
1992年 | 3015篇 |
1991年 | 3256篇 |
1990年 | 3118篇 |
1989年 | 3108篇 |
1988年 | 2770篇 |
1987年 | 2801篇 |
1986年 | 2902篇 |
1985年 | 2788篇 |
1984年 | 2189篇 |
1983年 | 1903篇 |
1982年 | 1310篇 |
1979年 | 2021篇 |
1978年 | 1559篇 |
1977年 | 1296篇 |
1975年 | 1455篇 |
1974年 | 1777篇 |
1973年 | 1760篇 |
1972年 | 1713篇 |
1971年 | 1658篇 |
1970年 | 1635篇 |
1969年 | 1571篇 |
1968年 | 1404篇 |
1967年 | 1420篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
A Yabuki S Suzuki M Matsumot M Kurohmaru Y Hayashi H Nishinakagawa 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2001,63(12):1339-1342
The proximal straight tubules of the female mouse kidney exhibit heavy periodic acid Schiff (PAS) staining in their brush borders and numerous cytoplasmic granules. In the present study, the female DBA/2Cr mouse kidney was examined, using various fixatives (formalin, PFA, PLP, Zamboni's, Bouin, or Carnoy solution) and various staining methods (HE, PAS, alcian blue, periodic acid methenamine-silver (PAM), toluidine blue, azan, or Congo red). Under azan and PAM, the staining pattern of the brush border was similar to that of PAS, and few effects of the fixative were observed. Cytoplasmic granules were clearly detected with PAM as well as PAS. However, these granules were not detected with Carnoy solution. Furthermore, distribution of granules differed between PAS and PAM. 相似文献
2.
3.
E. Conde A. M. Moreno I. Martin-Lacave A. Fernandez y H. Galera 《Anatomia, histologia, embryologia》1992,21(1):94-100
A systematic immunohistochemical study of the ultimobranchial tubule (UBT) has been carried out in 45 Wistar rats of different ages (0, 5, 10, 15, 20, 25, 30, 60 and 120 days). The existence of calcitonin immunoreactive cells in the UBT wall has been demonstrated in a 5-days old rat. In addition, immunohistochemical studies for thyroglobulin revealed positive staining in follicular cells connected to the UBT and, occasionally, in isolated cells lying within solid clusters from the UBT. These last results together with the continued and repeated existence of numerous mitosis and PAS (+) microfollicles, apparently rising from the UBT, support the hypothesis that the ultimobranchial body (UBB) may contribute partially to the formation of a part of the follicular component. 相似文献
4.
S A Dee 《Veterinary Clinics of North America: Food Animal Practice》1992,8(3):641-660
Porcine urogenital disease is the result of an imbalance of the normal microflora of the urinary and reproductive tracts brought about by hormonal, environmental, and management-related stress factors. Production and economic losses can be substantial, and diagnosing and treating the problem can be frustrating. Through proper hygiene, facility design, and culling procedures, the severity of the problem can be minimized. 相似文献
5.
M Onuma Y Yasutomi M Yamamoto S Watarai T Yasuda Y Kawakami 《Zentralblatt für Veterin?rmedizin. Reihe B. Journal of veterinary medicine. Series B》1989,36(2):139-147
Monoclonal antibody c143 against tumor-associated antigen (TAA) expressed on bovine leukemia cells was conjugated to liposomes containing adriamycin (ADM), and therapeutic effects of conjugates were examined in leukemic or preleukemic cows to prevent the progression of the disease. Five cows with TAA-positive in their peripheral blood lymphocytes were divided into two groups. Each group of cows received 4 injections of ADM alone (0.4 mg/kg) or c143-conjugated liposomes containing the same dose of ADM (L-AMD-c143) through the jugular vein at about 4 day intervals. In three animals treated with L-ADM-c143, the TAA-positive cells gradually decreased with treatment and finally two animals became TAA-negative during a 6 week period and a 14 week period after treatment, respectively. In the control, two animals treated with ADM alone showed only a slight decrease of TAA-positive cells. 相似文献
6.
Kevin R. Stuart Arnold G. Eversole David E. Brune 《Journal of the World Aquaculture Society》2001,32(1):105-111
Abstract.— The freshwater mussel Elliptio complanata was provided water containing green algae and cyanobacteria delivered from the Partitioned Aquaculture System (PAS) at eight flow rates to determine algal filtration rates as mg of particulate organic carbon (POC)/kg wet tissue weight per h. The dominant taxon in cyanobacterial waters was Microcystis while the dominant taxa in green algal waters were Scenedesmus and Ankistrodesmus . The cell counts of Scenedesmus and Ankistrodesmus were the only algal taxa that were significantly different between the incoming water and water filtered by mussels. Filtration rates of POC obtained from green algal water were significantly greater than from cyanobacteria-dominated waters at all flow rates. A significant increase in mean filtration rate was observed as flow rates increased. The filtration rate of green algae increased as POC concentration increased, peaking at 28 mg C/L. A maximum filtration rate was not observed with cyanobacterial waters. 相似文献
7.
Y Nagashima H Hirao S Furukawa K Hoshi M Akahane R Tanaka Y Yamane 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2001,63(11):1199-1202
Fifteen and eight mature beagles, without (normal group) and with experimental mitral regurgitation (MR group), respectively, were given 0.02 mg/kg/day digoxin powder for 10 days orally. The optimum time for sample collection after administration of digoxin was observed to be 8-18 hr and 10-22 hr in the normal and MR groups, respectively. In both groups, a stable concentration was reached after 3-5 days of treatment. No differences in plasma level were observed between sexes. The optimum concentration of digoxin was attained at an earlier stage than has been previously reported for both dogs and humans. 相似文献
8.
E Oohashi K Yagi Y Uzuka S Tanabe T Sarashina T Ishida 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2001,63(11):1241-1243
The purpose of this study was to evaluate seasonal influences on thyroid hormone levels of healthy outdoor dogs in Hokkaido. We surveyed serum basal total thyroxine (tT4), free thyroxine (fT4), and canine thyroid-stimulating hormone (cTSH) levels, and tT4 levels after administration of TSH for a year. Basal tT4 levels decreased in January, and increased in August and September. fT4 levels increased in January and November. No significant seasonal variation was found in cTSH. tT4 levels after administration of TSH in August and November increased. These results suggested that the thyroid gland may have been activated in November. We should take seasonal variation into consideration when thyroid function is tested. 相似文献
9.
The isolation of (+)-totarol as active compound against Mycobacterium tuberculosis is reported from Chamaecyparis nootkatensis outerbark. 相似文献
10.
Abstract. Anecdotal and circumstantial evidence have suggested that the Olsen test underestimates plant-available phosphorus (P) in basaltic soils in Northern Ireland. Therefore, the ability of this test to predict plant-available P in basaltic (and non-basaltic) soils was investigated by regressing Olsen-P data against herbage P indices calculated from plant tissue test data using the diagnosis and recommendation integrated system. The average Olsen-P concentration for a range of fields situated on basaltic soils was considerably lower than the average Olsen-P concentration for a range of fields situated on non-basaltic soils, and yet mean sward P status, as given by the herbage P indices, was similar for both groups of fields. Herbage P indices were also much better correlated with Olsen-P measurements in non-basaltic soils than in basaltic soils. Furthermore, at low Olsen-P values (≶9mgPL−1 ) some swards on basaltic soils were genuinely deficient in P, while others were sufficient or even in surplus for this nutrient. The results confirm that Olsen-P is inadequate as a predictor of plant-available P in basaltic soils. It is concluded that an alternative soil test is needed to provide a reliable assessment of plant-available P in basaltic soils, to prevent overuse of fertilizer and manure P and to minimize the amounts of P entering local watercourses. 相似文献