全文获取类型
收费全文 | 2032篇 |
免费 | 23篇 |
国内免费 | 178篇 |
出版年
2023年 | 25篇 |
2022年 | 30篇 |
2021年 | 55篇 |
2020年 | 59篇 |
2019年 | 72篇 |
2018年 | 93篇 |
2017年 | 36篇 |
2016年 | 47篇 |
2015年 | 65篇 |
2014年 | 154篇 |
2013年 | 126篇 |
2012年 | 64篇 |
2011年 | 87篇 |
2010年 | 66篇 |
2009年 | 87篇 |
2008年 | 88篇 |
2007年 | 86篇 |
2006年 | 68篇 |
2005年 | 94篇 |
2004年 | 62篇 |
2003年 | 57篇 |
2002年 | 54篇 |
2001年 | 22篇 |
2000年 | 17篇 |
1999年 | 32篇 |
1998年 | 29篇 |
1997年 | 35篇 |
1996年 | 40篇 |
1995年 | 36篇 |
1994年 | 42篇 |
1993年 | 33篇 |
1992年 | 30篇 |
1991年 | 36篇 |
1990年 | 28篇 |
1989年 | 30篇 |
1988年 | 29篇 |
1987年 | 28篇 |
1986年 | 14篇 |
1985年 | 27篇 |
1984年 | 34篇 |
1983年 | 28篇 |
1982年 | 12篇 |
1981年 | 10篇 |
1980年 | 10篇 |
1979年 | 7篇 |
1978年 | 10篇 |
1977年 | 11篇 |
1976年 | 9篇 |
1975年 | 7篇 |
1971年 | 5篇 |
排序方式: 共有2233条查询结果,搜索用时 14 毫秒
831.
832.
J. M. YOUNG 《The Annals of applied biology》1991,118(2):283-298
Comparative in planta studies with Pseudomonas syringae pv. syringae have established optimum conditions for disease expression in lilac in terms of inoculum concentration, host age and post-inoculation conditions (temperature and day-length). Reproducible disease reactions required an inoculum concentration exceeding the ED50, 5 × 106 cfu/ml, and a temperature for post-inoculation incubation not exceeding 19°C. A revised host range of P. syringae pv. syringae, proposed on the basis of confirmation of pathogenicity of strains to lilac, comprises 44 species from monocotyledonous and dicotyledonous plants. Nine new hosts Abelmoschus esculentus, Bromus willdenowii, Camellia sinensis, Centrosema pubescens, Citrullus lanatus, Cotoneaster sp., Cucumis melo, Populus×euramericana and Triticum aestivum, are recorded. A comparative laboratory study was made of strains of P. syringae pv. syringae using more than 30 selected biochemical and nutritional tests. The pathovar could be characterised on the basis of 11 of these which may prove to be useful determinative tests. 相似文献
833.
A new species, Propionibacterium innocuum, is proposed to accommodate strains of coryneform bacteria from human skin with phenotypic characters similar to those of the classical propionibacteria but differing in exhibiting primarily aerobic respiration and possessing a unique cell wall composition in which LL-diaminopimelic acid and arabinose occur together. The partial 16S rRNA sequence confirms an affinity with the genus Pro-pionibacterium and indicates that the species represents a distinct line within the genus. The type strain of Propionibacterium innocuum is NCTC 11082. 相似文献
834.
835.
中国千斤拔属植物的初步研究 总被引:7,自引:0,他引:7
本文叙述了千斤拔属名的拉丁学名的变换和研究情况,并研究该属植物国产种的分类、地理分布及其特点。进而对该属植物的习性和苞片、花序、花和叶等诸器官演化趋势作初步探讨,并对该属6个类群之间可能的演化关系、属的起源、分布中心和迁移路线等问题提出初设想。 相似文献
836.
837.
Immunodiffusion patterns of the different morphological types of female Haemonchus contortus (Rudolphi, 1803) indicate that the three phenotypes—smooth, linguiform, and knobbed—differ from each other serologically. Linguiform antigens gave five precipitin lines, knobbed gave four lines, and smooth gave three precipitin lines with rabbit antisera. Also, lines unite in a manner indicating marked antigenic differences between the three types. Since serological studies are considered to be sensitive tools in taxonomy, the present work indicates that taxonomic importance should be attached to the vulvar configurations in female H. contortus. 相似文献
838.
Jørgen Slots 《Archives of microbiology》1982,131(1):60-67
A total of 136 strains of Actinobacillus actinomycetemcomitans were studied for 135 features. All isolates were small nonmotile capnophilic gram-negative rods which grew with no requirement of X or V growth factors. They all decomposed hydrogen peroxide, were oxidase-negative and benzidine-positive, reduced nitrate, produced strong alkaline and acid phosphatases, and fermented fructose, glucose and mannose. Variable fermentation results were obtained with dextrin, maltose, mannitol and xylose. Some isolates produced small amounts of gas. Representative strains of Haemophilusaphrophilus were morphologically and biochemically quite similar to A. actinomycetemcomitans. Characters which should prove to be useful to identify and distinguish these two species include catalase reaction, fermentation of lactose, starch, sucrose and trehalose, and resistance to sodium fluoride. This information allows a rapid diagnosis by species and may be helpful in studies of infections involving these organisms.Abbreviations ONPG
O-nitrophenyl--d-galactopyranoside 相似文献
839.
ABSTRACT The surface structures of the elytra in twenty two species belonging to the subfamily Sericinae (Coleoptera, Melolonthidae) were observed by scanning electron microscopy. For viewing specific characters, elytral punctures and diffraction gratings on interstitial surface were focused on. The elytral punctures of observed Sericid beetles have three representative forms: horseshoe, ocellus, and crease types. The diffraction gratings of the elytra show three distinctive patterns: regular and parallel, discontinued, and interconnected and curved. These patterns of elytral punctures and diffraction gratings considered to be useful for identification. 相似文献
840.
Sei-Woong CHOI 《Entomological Research》2004,34(2):101-103
One species of Drepaninae, Tridrepana crocea (Leech), is added to the Korean fauna. Up to now, 23 species of Drepaninae are known in Korea. Diagnosis and the photographs of male and female genitalia of T. crocea are provided. 相似文献