全文获取类型
收费全文 | 1567篇 |
免费 | 9篇 |
国内免费 | 5篇 |
专业分类
林业 | 12篇 |
农学 | 18篇 |
基础科学 | 5篇 |
112篇 | |
综合类 | 662篇 |
农作物 | 61篇 |
水产渔业 | 6篇 |
畜牧兽医 | 646篇 |
园艺 | 7篇 |
植物保护 | 52篇 |
出版年
2014年 | 8篇 |
2012年 | 59篇 |
2011年 | 95篇 |
2010年 | 23篇 |
2009年 | 26篇 |
2008年 | 85篇 |
2007年 | 86篇 |
2006年 | 79篇 |
2005年 | 75篇 |
2004年 | 97篇 |
2003年 | 81篇 |
2002年 | 85篇 |
2001年 | 44篇 |
2000年 | 93篇 |
1999年 | 43篇 |
1998年 | 11篇 |
1995年 | 11篇 |
1994年 | 18篇 |
1993年 | 20篇 |
1992年 | 21篇 |
1991年 | 21篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1987年 | 7篇 |
1984年 | 14篇 |
1983年 | 7篇 |
1980年 | 7篇 |
1976年 | 8篇 |
1975年 | 8篇 |
1972年 | 7篇 |
1970年 | 10篇 |
1966年 | 11篇 |
1963年 | 13篇 |
1959年 | 7篇 |
1957年 | 7篇 |
1954年 | 12篇 |
1953年 | 14篇 |
1948年 | 7篇 |
1907年 | 17篇 |
1906年 | 19篇 |
1905年 | 15篇 |
1904年 | 17篇 |
1903年 | 13篇 |
1902年 | 7篇 |
1901年 | 10篇 |
1900年 | 9篇 |
1899年 | 10篇 |
1898年 | 17篇 |
1897年 | 10篇 |
1896年 | 15篇 |
排序方式: 共有1581条查询结果,搜索用时 93 毫秒
951.
952.
953.
Larson LJ Hageny TL Haase CJ Schultz RD 《Veterinary therapeutics : research in applied veterinary medicine》2006,7(2):107-112
Two canine distemper virus (CDV) vaccine types are currently commercially available: modified-live virus (MLV) vaccines and a canarypox recombinant CDV (rCDV) vaccine (Recombitek, Merial). This study compared the ability of the rCDV vaccine and MLV vaccines to significantly enhance (boost) the antibody response of previously immunized adult and juvenile dogs. A significant (fourfold or greater) increase in titer occurred in significantly more dogs revaccinated with Recombitek C-4 or Recombitek C-6 than with the MLV-CDV vaccines. This study demonstrates that Recombitek, the only vaccine for dogs containing rCDV, is more likely to significantly boost the CDV antibody response in previously vaccinated dogs than are the MLV-CDV vaccines. Because rCDV vaccine can boost the antibody titer of dogs previously vaccinated with an MLV vaccine, it can and should be used when core vaccines are readministered. 相似文献
954.
Ellsworth MA Fairbanks KK Behan S Jackson JA Goodyear M Oien NL Meinert TR Leyh RD 《Veterinary therapeutics : research in applied veterinary medicine》2006,7(3):295-304
This study demonstrated that the bovine viral diarrhea virus (BVDV; types 1 and 2) fractions of a multivalent vaccine protected pregnant heifers and their fetuses at 149 to 217 days of gestation against exposure to calves persistently infected with BVDV type 2a. Eighty percent (eight of 10) of the control heifers were viremic at least 1 day following challenge, whereas all (20 of 20) BVDV-vaccinated heifers were virus isolation-negative on all postchallenge assessment days. Ninety percent (nine of 10) of the calves born to control heifers but only 5% (one of 20) of calves born to BVDV-vaccinated heifers seroconverted to BVDV type 2 before ingesting colostrum. One calf born to a control heifer was persistently infected. No calves from BVDV-vaccinated heifers were persistently infected. 相似文献
955.
Cooper AA Gitler AD Cashikar A Haynes CM Hill KJ Bhullar B Liu K Xu K Strathearn KE Liu F Cao S Caldwell KA Caldwell GA Marsischky G Kolodner RD Labaer J Rochet JC Bonini NM Lindquist S 《Science (New York, N.Y.)》2006,313(5785):324-328
Alpha-synuclein (alphaSyn) misfolding is associated with several devastating neurodegenerative disorders, including Parkinson's disease (PD). In yeast cells and in neurons alphaSyn accumulation is cytotoxic, but little is known about its normal function or pathobiology. The earliest defect following alphaSyn expression in yeast was a block in endoplasmic reticulum (ER)-to-Golgi vesicular trafficking. In a genomewide screen, the largest class of toxicity modifiers were proteins functioning at this same step, including the Rab guanosine triphosphatase Ypt1p, which associated with cytoplasmic alphaSyn inclusions. Elevated expression of Rab1, the mammalian YPT1 homolog, protected against alphaSyn-induced dopaminergic neuron loss in animal models of PD. Thus, synucleinopathies may result from disruptions in basic cellular functions that interface with the unique biology of particular neurons to make them especially vulnerable. 相似文献
956.
Recent Greenland ice mass loss by drainage system from satellite gravity observations 总被引:3,自引:0,他引:3
Luthcke SB Zwally HJ Abdalati W Rowlands DD Ray RD Nerem RS Lemoine FG McCarthy JJ Chinn DS 《Science (New York, N.Y.)》2006,314(5803):1286-1289
Mass changes of the Greenland Ice Sheet resolved by drainage system regions were derived from a local mass concentration analysis of NASA-Deutsches Zentrum für Luftund Raumfahrt Gravity Recovery and Climate Experiment (GRACE mission) observations. From 2003 to 2005, the ice sheet lost 101 +/- 16 gigaton/year, with a gain of 54 gigaton/year above 2000 meters and a loss of 155 gigaton/year at lower elevations. The lower elevations show a large seasonal cycle, with mass losses during summer melting followed by gains from fall through spring. The overall rate of loss reflects a considerable change in trend (-113 +/- 17 gigaton/year) from a near balance during the 1990s but is smaller than some other recent estimates. 相似文献
957.
Fermi LAT Collaboration Ackermann M Ajello M Ballet J Barbiellini G Bastieri D Belfiore A Bellazzini R Berenji B Blandford RD Bloom ED Bonamente E Borgland AW Bregeon J Brigida M Bruel P Buehler R Buson S Caliandro GA Cameron RA Caraveo PA Cavazzuti E Cecchi C Çelik Ö Charles E Chaty S Chekhtman A Cheung CC Chiang J Ciprini S Claus R Cohen-Tanugi J Corbel S Corbet RH Cutini S de Luca A den Hartog PR de Palma F Dermer CD Digel SW do Couto e Silva E Donato D Drell PS Drlica-Wagner A Dubois R 《Science (New York, N.Y.)》2012,335(6065):189-193
Gamma-ray binaries are stellar systems containing a neutron star or black hole, with gamma-ray emission produced by an interaction between the components. These systems are rare, even though binary evolution models predict dozens in our Galaxy. A search for gamma-ray binaries with the Fermi Large Area Telescope (LAT) shows that 1FGL J1018.6-5856 exhibits intensity and spectral modulation with a 16.6-day period. We identified a variable x-ray counterpart, which shows a sharp maximum coinciding with maximum gamma-ray emission, as well as an O6V((f)) star optical counterpart and a radio counterpart that is also apparently modulated on the orbital period. 1FGL J1018.6-5856 is thus a gamma-ray binary, and its detection suggests the presence of other fainter binaries in the Galaxy. 相似文献
958.
959.
The Pib gene in rice confers resistance to a wide range of races of the rice blast pathogen, Magnaporthe oryzae, including race IE1k that overcomes Pita, another broad-spectrum resistance gene. In this study, the presence of Pib was determined in 164 rice germplasm accessions from a core subset of the National Small Grains Collection utilizing DNA markers and pathogenicity assays. The presence of Pib was evaluated with two simple sequence repeat (SSR) markers and a dominant marker (Pib-dom) derived from the Pib gene sequence. Pathogenicity assays using two avirulent races (IE1k and IB1) and a virulent race (IB54) were performed to verify the resistance responses of accessions. Of the 164 accessions evaluated, 109 contained the Pib gene as determined using both SSR markers and pathogenicity assays, albeit different haplotypes were detected. The remaining 52 germplasm accessions were different in their responses to the blast races IB54, IE1k, and IB1, thus indicating the presence of R gene(s) other than Pib. The accessions characterized in this study could be used for marker-assisted breeding to improve blast resistance in indica and japonica cultivars worldwide. 相似文献
960.