全文获取类型
收费全文 | 72511篇 |
免费 | 3791篇 |
国内免费 | 43篇 |
专业分类
林业 | 3382篇 |
农学 | 2192篇 |
基础科学 | 358篇 |
8980篇 | |
综合类 | 13234篇 |
农作物 | 2740篇 |
水产渔业 | 3527篇 |
畜牧兽医 | 36622篇 |
园艺 | 809篇 |
植物保护 | 4501篇 |
出版年
2018年 | 1087篇 |
2017年 | 1215篇 |
2016年 | 1090篇 |
2015年 | 909篇 |
2014年 | 1155篇 |
2013年 | 2603篇 |
2012年 | 2130篇 |
2011年 | 2445篇 |
2010年 | 1668篇 |
2009年 | 1723篇 |
2008年 | 2443篇 |
2007年 | 2410篇 |
2006年 | 2203篇 |
2005年 | 2069篇 |
2004年 | 1921篇 |
2003年 | 1951篇 |
2002年 | 1805篇 |
2001年 | 2206篇 |
2000年 | 2161篇 |
1999年 | 1766篇 |
1998年 | 696篇 |
1997年 | 722篇 |
1996年 | 667篇 |
1995年 | 745篇 |
1994年 | 672篇 |
1993年 | 690篇 |
1992年 | 1296篇 |
1991年 | 1389篇 |
1990年 | 1293篇 |
1989年 | 1279篇 |
1988年 | 1226篇 |
1987年 | 1261篇 |
1986年 | 1214篇 |
1985年 | 1237篇 |
1984年 | 1028篇 |
1983年 | 904篇 |
1979年 | 997篇 |
1978年 | 794篇 |
1977年 | 726篇 |
1976年 | 731篇 |
1975年 | 786篇 |
1974年 | 988篇 |
1973年 | 872篇 |
1972年 | 930篇 |
1971年 | 894篇 |
1970年 | 797篇 |
1969年 | 846篇 |
1968年 | 700篇 |
1967年 | 807篇 |
1966年 | 685篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
12.
13.
14.
15.
The plants of field bean var. Nadwiślaνski were detopped after about 1 month since the beginning of flowering and after that all flower buds were removed from some plants. The effect of a change in the trophic balance on the setting and subsequent growth of root nodules was studied.
The removal of pods had the greater effect on the increase in the weight of the remaining organs than the detopping of plants. Detopping retarded the ageing of the plants and delayed the phase of the greatest reduction of the number of pods. The detopping of plants revealed their considerable compensative possibilities in terms of production of the pod weight and the potential of leaves for biomass production. The data obtained indicate that plant detopping may disturb the root–bacteria exchange of signals, necessary to initiate the nodule development, while the further growth of nodules depends, above all, on the amount of available photosynthates.
A very high correlation between the dry weight of the whole plant to the dry weight of leaves ratio and the weight of nodules was observed. It proves the importance of the trophic balance of the plant for the root nodule weight production. 相似文献
The removal of pods had the greater effect on the increase in the weight of the remaining organs than the detopping of plants. Detopping retarded the ageing of the plants and delayed the phase of the greatest reduction of the number of pods. The detopping of plants revealed their considerable compensative possibilities in terms of production of the pod weight and the potential of leaves for biomass production. The data obtained indicate that plant detopping may disturb the root–bacteria exchange of signals, necessary to initiate the nodule development, while the further growth of nodules depends, above all, on the amount of available photosynthates.
A very high correlation between the dry weight of the whole plant to the dry weight of leaves ratio and the weight of nodules was observed. It proves the importance of the trophic balance of the plant for the root nodule weight production. 相似文献
16.
David F. Edwards DVM John W. Parker DVM J. Erby Wilkinson DVM PhD R. Gayman Helman DVM PhD 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1993,7(3):169-176
Plasma cell myelomas in horses have been reported infrequently. Data from 10 cases, 9 from the literature and 1 new case, are used to characterize the disease in the horse. Hot-blooded horses (7/10), specifically Quarter Horses (4/10), were most often affected. Median age at diagnosis was 11 years (range, 3 mo-22 yr) and both male (5) and female horses (5) were represented equally. Clinical findings included weight loss (6/8), anorexia (4/8), fever (4/8), limb edema (4/8), pneumonia (3/8), rear leg paresis/ataxia (3/8), epistaxis (3/8), palpable lymphadenopathy (2/8), and bone pain (2/8). Anemia (8/8) was present routinely, and in three horses, RBCs were macrocytic. Leukopenia (2/8), thrombocy-topenia (2/8), and circulating plasma cells (3/8) were variable findings. Except for abnormal protein concentrations and hyponatremia (3), abnormal results from serum biochemical analysis including hypo-cholesterolemia (1), hypercalcemia (1), and azotemia (1) were reported infrequently. Hyperproteinemia (8/9), hypoalbuminemia (7/9), and hyperglobulinemia (8/9) were characteristic but not invariable findings. Monoclonal proteins (7/7) were detected in the α2, β, or γ region by serum electrophoresis. The paraprotein's heavy chain, determined in four horses, was a subclass of IgG. Three horses had decreased concentrations of normal immunoglobulins. Variable proteinuria (trace to 4+) was detected by routine urinalysis in four of six horses. Bence Jones proteinuria was detected in one of five horses (heat precipitation) and monoclonal proteins were detected in two of three electrophoresed urine samples. Three of the horses had lytic bone lesions detected radiographically. Bone marrow aspirates were diagnostic in two of five horses. Atypical plasma cells or increased numbers of plasma cells or both were present in histologic sections of bone marrow in six of eight horses. Common extraosseous sites of plasma cell infiltration included lymph nodes (8/8), kidney (5/8), spleen (5/8), liver (3/8), lung (3/8), brain (2/8), and orbit (2/8). Two horses had intracellular and extracellular crystalline deposits. 相似文献
17.
Platelet aggregation in healthy and sick cats after adding various aggregating agents is described. Feline platelets aggregate irreversibly in response to 0.15-1.0 micrograms/ml collagen, 1 microM ADP, 0.3 IU/ml test-thrombin and 0.71 NIH/ml Topostasin. Epinephrine, ristocetin and kaolin failed to cause aggregation. The aggregation function was decreased in a cat with liver damage and icterus; in 2 cats with uremia platelet aggregation was normal. Acetylsalicylic acid (ASA) (10 mg/kg iv) inhibits platelet aggregation in the presence of collagen in low concentrations; high concentrations of collagen succeeded in inducing platelet aggregation. 相似文献
18.
F Urayama T Sato H Shibuya W Shirai M Matsutani R Yamazaki 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2001,63(11):1249-1252
An apocrine adenocarcinoma was observed in the subcutis of the abdomen of golden hamster. Histologically, the tumor cells irregularly formed multiple layers of cysts and some detached cells were presented in the cystic space. PAS stain with alpha-amylase digestion revealed PAS-positive alpha-amylase-resistant granules in the cytoplasm. Immunohistochemically, cytokeratin was demonstrated in the tumor cells. By electron microscopy, the tumor cells had an oval nucleus with invagination, abundant cytoplasmic organelles and microvilli protruding into the intercellular spaces. 相似文献
19.
20.
B Hofírek P Horín M Granátová M Machatková J Franz I Svoboda J Blecha 《Veterinární medicína》1986,31(3):129-140
A trial was performed with heifers at the age of six to seven months. The animals were experimentally infected with the lymphocytes of a virus-productive donor. Infection was produced in all the nine cases, as demonstrated by means of the positive syncytial test. As indicated by the results of the trial, the antibodies to the enzootic bovine leucosis virus (BLV) were produced soon after experimental infection. A high sensitivity of the serum-neutralization test and the ELISA method was demonstrated in this connection: by these methods, the antibodies were identified already two to three weeks after experimental infection whereas by the immunodiffusion test they could be detected only after five weeks. Twenty-four animals were exposed to natural contact infection. Within 270 days of the trial, the disease after contact was recorded only in one heifer out of the four that were in close contact with the experimentally infected animals. In this case, as compared with experimental infection, the antibodies were produced much later--after 85 to 93 days. Leucosis was recorded in none of the remaining animals. The reasons why such a favourable result was obtained were the thorough disinfection of the stables after blood collections and the strict observance of the aseptic conditions. The results of experimental infection in three cows were identical with those obtained in young cattle. In the experimentally infected dairy cows, antibodies in milk were determined by the ELISA method. As found, in milk the antibodies to BLV appear two to three weeks later than they do in serum. The ELISA method of BLV antibody detection can be used for the identification of infected animals in herds where enzootic bovine leucosis occurs. 相似文献