全文获取类型
收费全文 | 8165篇 |
免费 | 840篇 |
国内免费 | 3篇 |
专业分类
9008篇 |
出版年
2023年 | 52篇 |
2022年 | 130篇 |
2021年 | 220篇 |
2020年 | 126篇 |
2019年 | 146篇 |
2018年 | 183篇 |
2017年 | 138篇 |
2016年 | 251篇 |
2015年 | 432篇 |
2014年 | 462篇 |
2013年 | 540篇 |
2012年 | 717篇 |
2011年 | 627篇 |
2010年 | 348篇 |
2009年 | 326篇 |
2008年 | 467篇 |
2007年 | 451篇 |
2006年 | 418篇 |
2005年 | 358篇 |
2004年 | 332篇 |
2003年 | 289篇 |
2002年 | 241篇 |
2001年 | 94篇 |
2000年 | 87篇 |
1999年 | 98篇 |
1998年 | 86篇 |
1997年 | 61篇 |
1996年 | 40篇 |
1995年 | 37篇 |
1994年 | 51篇 |
1993年 | 45篇 |
1992年 | 63篇 |
1991年 | 62篇 |
1990年 | 58篇 |
1989年 | 54篇 |
1988年 | 57篇 |
1987年 | 33篇 |
1986年 | 53篇 |
1985年 | 40篇 |
1984年 | 40篇 |
1983年 | 34篇 |
1982年 | 38篇 |
1981年 | 35篇 |
1979年 | 35篇 |
1978年 | 40篇 |
1976年 | 34篇 |
1974年 | 32篇 |
1972年 | 29篇 |
1969年 | 32篇 |
1968年 | 28篇 |
排序方式: 共有9008条查询结果,搜索用时 46 毫秒
41.
42.
Microplot experiments were conducted to evaluate the effects of inoculum level and time of application of Paecilomyces lilacinus on the protection of tomato against MeIoidogyne incognita. The best protection against M. incognita was attained with 10 and 20 g of fungus-infested wheat kernels per microplot which resulted in a threefold and fourfold increase in tomato yield, respectively, compared with tomato plants treated with this nematode alone. Greatest protection against this pathogen was attained when P. lilacinus was delivered into soil 10 days before planting and again at planting. Yield was increased twofold compared with yield in nematode-alone plots and plots with M. incognita plus the fungus. Percentages of P. lilacinus-infected egg masses were greatest in plots treated at midseason or at midseason plus an early application, compared with plots treated with the fungus 10 days before planting and (or) at planting time. 相似文献
43.
44.
Homologues of catalytic domains of Cellulomonas glucanases found in fungal and Bacillus glycosidases 总被引:1,自引:0,他引:1
Catherine A. West rzej Elzanowski Lai-Su Yeh Winona C. Barker 《FEMS microbiology letters》1989,59(1-2):167-172
We demonstrate homology between the catalytic domains of exoglucanase (1,4-beta-D-glucan cellobiohydrolase, EC 3.2.1.91) from Cellulomonas fimi and those of endoxylanases (1,4-beta-D-xylan xylanohydrolases, EC 3.2.1.8) from Bacillus sp. strain C-125 and the fungus Cryptococcus albidus; and between the catalytic domains of endoglucanase (1,4-(1,3:1,4)-beta-D-glucan 4-glucanohydrolase, EC 3.2.1.4) from Cellulomonas fimi and exoglucanase II from Trichoderma reesei. These five enzymes apparently evolved by reshuffling of two catalytic domains and several substrate-binding domains. 相似文献
45.
Laboratory reared Ixodes scapularis proved to be an efficient vector of Babesia odocoilei Emerson and Wright between white-tailed deer (Odocoileus virginianus). Transtadial survival of the babesia occurred between nymph and adult stages of the tick, and the adult stage transmitted the babesia. 相似文献
46.
Immobilization of lipase from Candida cylindraceae and its use in the synthesis of menthol esters by transesterification. 总被引:2,自引:0,他引:2
Lipase (EC 3.1.1.3) from Candida cylindraceae has been immobilized by the cellulose-titanium chloride method, and on EP-400 polyethylene, with and without glutaraldehyde crosslinking, to give active preparations when assessed by their ability to catalyse the hydrolysis of tributyrin. In both cases, the use of glutaraldehyde crosslinking was shown to improve the stability of the preparations for repeated use. The lipase immobilized on EP-400 polyethylene was found to be effective in transesterification using tributyrin or triacetin as acyl donors with l-menthol as acceptor. The production of methyl butanoate and of methyl acetate using this immobilized preparation was in each case enhanced in the presence of Amberlite IR 47 Anion exchange resin (OH form). 相似文献
47.
Multicolor in situ hybridization and linkage analysis order Charcot-Marie-Tooth type I (CMTIA) gene-region markers. 下载免费PDF全文
R V Lebo E D Lynch T D Bird M S Golbus D F Barker P O''''Connell P F Chance 《American journal of human genetics》1992,50(1):42-55
This study demonstrates a clear and current role for multicolor in situ hybridization in expediting positional cloning studies of unknown disease genes. Nine polymorphic DNA cosmids have been mapped to eight ordered locations spanning the Charcot-Marie-Tooth type 1 (CMT1A) disease gene region in distal band 17p11.2, by multicolor in situ hybridization. When used with linkage analysis, these methods have generated a fine physical map and have firmly assigned the CMT1A gene to distal band 17p11.2. Linkage analysis with four CMT1A pedigrees mapped the CMT1A gene with respect to two flanking markers (8B10-5 cM[LOD 5.2]-CMT1A-3.5 cM[LOD 5.3]-10E4). Additional loci were physically mapped and ordered by in situ hybridization and analysis of phase-known recombinants in CMT1A pedigrees. The order determined by multicolor in situ hybridization was 17cen-LEW301-8B10-5H5/6A9-VAW409- 5G7-6G1-4A11-VAW412-10E4-pter. Two ordered probes, 4A11 and 6G1, reside on the same 440-kb partial SfiI restriction fragment. These data demonstrate the ability of in situ hybridization to resolve loci within 0.5 Mb on early-metaphase chromosomes. Multicolor in situ hybridization also excluded the possibility of pericentric inversions in two unrelated patients with CMT1 and neurofibromatosis type 1. When used with pulsed-field gel electrophoresis, multicolor in situ hybridization can establish physical location, order, and distance in closely spaced chromosome loci. 相似文献
48.
The mechanosensitive properties of large-conductance Ca2+-activated K+ (BK) channels from embryonic rat neuroepithelium were investigated with the cell-attached and inside-out configurations of
the patch-clamp technique. The channels were activated in both recording configurations by negative pressures applied to the
patch electrode, but reversal of the effect was total and immediate in inside-out patches whereas it was incomplete and delayed
in on-cell patches. This mechanosensitivity was not mediated by Ca2+ ions or fatty acids, suggesting that it is an intrinsic property of these channels. Cytochalasin B did not affect mechanosensitivity
in on-cell patches but increased it in inside-out patches. Kinetic studies showed that stretch increased the mean open time
of the channels and decreased the slowest time constant of their closed-time distributions. The present as well as previous
results suggest complex interactions between embryonic BK channels and their membranous and submembranous environment.
Received: 1 February 1996/Revised: 25 March 1996 相似文献
49.
50.