全文获取类型
收费全文 | 110892篇 |
免费 | 6054篇 |
国内免费 | 65篇 |
专业分类
林业 | 4632篇 |
农学 | 3846篇 |
基础科学 | 683篇 |
13568篇 | |
综合类 | 18239篇 |
农作物 | 3841篇 |
水产渔业 | 5830篇 |
畜牧兽医 | 57855篇 |
园艺 | 1383篇 |
植物保护 | 7134篇 |
出版年
2018年 | 1646篇 |
2017年 | 1743篇 |
2016年 | 1630篇 |
2015年 | 1386篇 |
2014年 | 1704篇 |
2013年 | 4052篇 |
2012年 | 3111篇 |
2011年 | 3791篇 |
2010年 | 2596篇 |
2009年 | 2626篇 |
2008年 | 3901篇 |
2007年 | 3600篇 |
2006年 | 3503篇 |
2005年 | 3183篇 |
2004年 | 3263篇 |
2003年 | 3252篇 |
2002年 | 2986篇 |
2001年 | 3892篇 |
2000年 | 3956篇 |
1999年 | 3146篇 |
1998年 | 1368篇 |
1997年 | 1226篇 |
1996年 | 1142篇 |
1995年 | 1360篇 |
1994年 | 1260篇 |
1993年 | 1150篇 |
1992年 | 2480篇 |
1991年 | 2535篇 |
1990年 | 2616篇 |
1989年 | 2401篇 |
1988年 | 2295篇 |
1987年 | 2237篇 |
1986年 | 2236篇 |
1985年 | 2112篇 |
1984年 | 1787篇 |
1983年 | 1590篇 |
1982年 | 992篇 |
1981年 | 930篇 |
1979年 | 1551篇 |
1978年 | 1220篇 |
1977年 | 1089篇 |
1976年 | 1023篇 |
1975年 | 1103篇 |
1974年 | 1209篇 |
1973年 | 1267篇 |
1972年 | 1266篇 |
1971年 | 1141篇 |
1970年 | 1083篇 |
1969年 | 1151篇 |
1967年 | 998篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
X M Zhang W Herbst H Lange-Herbst T Schliesser 《Zentralblatt für Veterin?rmedizin. Reihe B. Journal of veterinary medicine. Series B》1989,36(10):765-770
1,268 sera collected from slaughtered pigs in Hassia (FRG) from 1986 to 1988 were tested for antibodies against porcine and human influenza A virus strains using the single radial haemolysis test (SRHT). Antibodies against the porcine strains (subtype H1N1) A/Swine/Arnsberg/1/81, A/Swine/Iowa/15/30 and A/New Jersey/7/76 were detected in 411 (32.4%), 318 (25.1%) and 304 (24.0%) of sera, respectively. Up to 1988 a slight increase (10%) in the seroprevalence to A/Swine/Arnsberg/1/81 was noticed, whereas the results obtained with the other strains showed little variation. Antibodies against the human H1N1 strain A/Singapore/6/86 were only found in sera collected 1987 and 1988 in rates of 1.6% and 3.0%. Serological indication of infections with the human H3N2 strains A/Victoria/1/75, A/Hong Kong/1/68 and A/Philippines/2/82 could be shown in 286 (22.6%), 178 (14.4%) and 135 (10.6%) of the serum samples. Within the three year period the rate of sera positive for antibodies against A/Philippines/2/82 increased from 6.5% to 23.0%, whereas no variation in the rates were found using the other H3N2 strains. Antibodies simultaneously against porcine (H1N1) and human (H3N2) virus strains were detected in 9.9% of all sera tested. 相似文献
32.
A tumor of the third eyelid gland was diagnosed in a 13 year old female Chihuahua. Histopathology of the excised tissue revealed an apocrine adnexoma with squamous metaplasia. The literature regarding prolapse and tumors of the third eyelid gland was reviewed. No case with similar morphology to this tumor was described to our knowledge. 相似文献
33.
Ovine-derived fibroblasts were used to validate an insulin-like growth factor I (IGF-I) membrane-receptor binding assay system. Competitive binding using fibroblasts revealed that half-maximal inhibition of 125I-IGF-I binding by IGF-I was 2.3 nM. SDS-polyacrylamide gel electrophoresis analysis of specific protein-associated 125I-IGF-I was consistent with the migration of 125I-IGF-I-labeled Type I IGF receptor alpha-subunits at Mr 133,000 daltons. Further, the efficiency of two cell solubilization methods was examined and time-dependent binding equilibrium was determined for the membrane assay system. Satellite cell-derived myotubes were subsequently isolated from primary satellite cell cultures established from the semimembranosus muscles of high and low efficiency-of-gain (EOG) Targhee rams, and IGF-I receptor dynamics were measured. A membrane competitive binding study revealed that half-maximal inhibition of 125I-IGF-I binding was achieved by 1-ng IGF-I for low, and 10-ng IGF-I for high, EOG myotube membrane preparations. Kd values were similar between the high EOG (4.78 nM) and low EOG (2.95 nM) groups; however, receptor concentrations (Bmax) appeared to differ between groups. High EOG membrane receptor Bmax was 3.88 pmole/micrograms protein (19.87 pmole/micrograms DNA), whereas low EOG membrane receptor Bmax was 1.22 pmole/micrograms protein (9.28 pmole/micrograms DNA). These preliminary findings support the hypothesis that genetic selection for EOG results in altered satellite cell responsiveness to IGF-I. 相似文献
34.
35.
J Jieyuan P B Spradbrow 《Zentralblatt für Veterin?rmedizin. Reihe B. Journal of veterinary medicine. Series B》1992,39(5):388-390
Chickens were given various fowlpox vaccines on food pellets--a commercial vaccine (strain M), and the same strain after a single passage on chorio-allantoic membrane or in chicken embryo fibroblasts. All three oral vaccines induced antibodies at levels similar to those induced by commercial strain M administered to the wingweb. The oral vaccine derived from chorio-allantoic membrane gave protection similar to that obtained with vaccine administered by the wingweb, but this required a thousandfold more virus. 相似文献
36.
T Tsuboi Y Kanazawa T Syoji S Tokuhisa 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1992,54(6):1179-1181
Bovine follicular oocytes collected from bovine ovaries were exposed to bovid herpesvirus 1 (BHV-1). After washings, these oocytes were cultured to mature. As a result BHV-1 could not be removed from the oocytes and could replicate in the oocytes with cumulus cells, but not in the oocytes without the cells. Moreover, the specific fluorescence for BHV-1 was detected in the cumulus cells by a indirect immunofluorescent technique. Therefore these findings suggested BHV-1 could be absorbed in the oocytes but the replication of BHV-1 was done in the cumulus cells. 相似文献
37.
K Adachi A Yoshimoto T Hasegawa T Shimizu Y Goto S Makimura 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1992,54(6):1081-1084
Due to the potential for anti-erythrocyte membrane antibodies as possible enhancers of erythrocyte destruction, the presence of serum anti-erythrocyte membrane antibodies in 31 dogs with Babesia gibsoni infection admitted to a veterinary hospital was investigated by an enzyme linked immunosorbent assay (ELISA) and immunoblotting analyses. This infection resulted in an increase of anti-erythrocyte membrane antibodies in 84% (IgG) and 74% (IgM) of 31 infected dogs, respectively. This was confirmed by the similarity in the protein profiles of the erythrocyte membrane antigens immunoblotted with rabbit antiserum to dog erythrocyte membrane antigens and infected dog serum. These results suggest the production of anti-erythrocyte membrane antibodies was induced by B. gibsoni infection. 相似文献
38.
In this clinical study, a diaphragmatic peritoneo-pericardial hernia in an eight month-old Persian cat is reported. The diagnostic procedure is described, and the clinical symptoms and diagnostic possibilities are discussed. 相似文献
39.
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
40.
P. Banik 《Journal of Agronomy and Crop Science》1996,176(5):289-294
A field experiment was conducted during the winter season of 1992–93 and 1993–94 at Agricultural Experimental Farm, Giridih, Bihar to evaluate the intercropping systems of legumes, gram ( Cicer arietinum L.), pea ( Pisum sativum ) and lentil ( Lens culinaris ) with wheat ( Triticum aestivum ) in 1:1 and 2:1 'row replacement series'. Intercropping systems were assessed on the basis of new indices termed as actual yield loss (AYL) and intercropping advantage (IA). This paper highlights the comparative effectiveness of evaluating the intercropping systems through the existing intercropping indices like LER, RCC, aggressivity. The indices AYL and IA seem to be more appropriate particularly when per plant yield is considered. Intercropping reduced the yield of component crops compared with respective pure stands. Wheat + pea in 1:1 row replacement series gave the highest wheat yield equivalent value (3.02 t ha−1 ) followed by wheat + lentil (2.91 tha−1 ). When the actual sown proportion was considered wheat + lentil (1:1) resulted in maximum AYL (+0.610) and IA (+0.279) values. This treatment also gave the maximum monetary advantage (Rs 5985.45 ha−1 ). 相似文献