全文获取类型
收费全文 | 28309篇 |
免费 | 2312篇 |
国内免费 | 1372篇 |
出版年
2024年 | 56篇 |
2023年 | 263篇 |
2022年 | 649篇 |
2021年 | 965篇 |
2020年 | 701篇 |
2019年 | 896篇 |
2018年 | 992篇 |
2017年 | 736篇 |
2016年 | 1141篇 |
2015年 | 1719篇 |
2014年 | 2036篇 |
2013年 | 2150篇 |
2012年 | 2617篇 |
2011年 | 2471篇 |
2010年 | 1509篇 |
2009年 | 1431篇 |
2008年 | 1677篇 |
2007年 | 1554篇 |
2006年 | 1383篇 |
2005年 | 1201篇 |
2004年 | 1166篇 |
2003年 | 949篇 |
2002年 | 749篇 |
2001年 | 515篇 |
2000年 | 441篇 |
1999年 | 358篇 |
1998年 | 229篇 |
1997年 | 194篇 |
1996年 | 183篇 |
1995年 | 139篇 |
1994年 | 127篇 |
1993年 | 81篇 |
1992年 | 117篇 |
1991年 | 101篇 |
1990年 | 101篇 |
1989年 | 77篇 |
1988年 | 57篇 |
1987年 | 53篇 |
1986年 | 32篇 |
1985年 | 37篇 |
1984年 | 40篇 |
1983年 | 15篇 |
1982年 | 16篇 |
1981年 | 10篇 |
1980年 | 7篇 |
1976年 | 6篇 |
1975年 | 6篇 |
1973年 | 5篇 |
1971年 | 5篇 |
1967年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
Identification of molecular markers in soybean comparing RFLP,RAPD and AFLP DNA mapping techniques 总被引:16,自引:0,他引:16
Jhy-Jhu Lin Jonathan Kuo Jin Ma James A. Saunders Hunter S. Beard Margaret H. MacDonald William Kenworthy George N. Ude Benjamin F. Matthews 《Plant Molecular Biology Reporter》1996,14(2):156-169
Three different DNA mapping techniques—RFLP, RAPD and AFLP—were used on identical soybean germplasm to compare their ability
to identify markers in the development of a genetic linkage map. Polymorphisms present in fourteen different soybean cultivars
were demonstrated using all three techniques. AFLP, a novel PCR-based technique, was able to identify multiple polymorphic
bands in a denaturing gel using 60 of 64 primer pairs tested. AFLP relies on primers designed in part on sequences for endonuclease
restriction sites and on three selective nucleotides. The 60 diagnostic primer pairs tested for AFLP analysis each distinguished
on average six polymorphic bands. Using specific primers designed for soybean fromEco RI andMse I restriction site sequences and three selective nucleotides, as many as 12 polymorphic bands per primer could be obtained
with AFLP techniques. Only 35% of the RAPD reactions identified a polymorphic band using the same soybean cultivars, and in
those positive reactions, typically only one or two polymorphic bands per gel were found. Identification of polymorphic bands
using RFLP techniques was the most cumbersome, because Southern blotting and probe hybridization were required. Over 50% of
the soybean RFLP probes examined failed to distinguish even a single polymorphic band, and the RFLP probes that did distinguish
polymorphic bands seldom identified more than one polymorphic band. We conclude that, among the three techniques tested, AFLP
is the most useful. 相似文献
102.
A 4-chlorophenol (4-CP)-degrading bacterium, strain CPW301, was isolated from soil and identified as Comamonas testosteroni. This strain dechlorinated and degraded 4-CP via a meta-cleavage pathway. CPW301 could also utilize phenol as a carbon and energy source without the accumulation of any metabolites via the same meta-cleavage pathway. When phenol was added as a additional substrate, CPW301 could degrade 4-CP and phenol simultaneously. The addition of phenol greatly accelerated the degradation of 4-CP due to the increased cell mass. The simultaneous degradation of the 4-CP and phenol is useful not only for enhanced cell growth but also for the bioremediation of both compounds, which are normally present in hazardous waste sites as a mixture. 相似文献
103.
固定化虫荧光素酶光纤传感器 总被引:1,自引:0,他引:1
固定化虫荧光素酶光纤传感器蔡谨,王顺光,杨歧生,吉鑫松(浙江大学化工系生化教研室,杭州310027;中国科学院上海生物化学研究所,200031)关键词虫荧光素酶,ATP,固定化酶,光纤生物传感器ATP是生物体内极为重要的能量物质。如何准确快速地定量A... 相似文献
104.
采到骨状拟夏孢锈(Uredinopsis ossiformis Kamei)为中国新记录种。 相似文献
105.
钙调素对细胞周期的调节 总被引:1,自引:0,他引:1
RC3细胞是一种用真核表达载体1~(CaM)转染NIH 3T3细胞建成的可调钙凋素(Calmodulin,CaM)高表达细胞模型。通过分子杂交及蛋白免疫印迹方法证实在地塞米松(Dexamethasome,DXM)作用下,RC3细胞可高表达CaM。CaM的过表达使G_1期细胞减少,S期细胞增加;CaM拮抗剂三氟拉嗪(trifluoperazine,TFP)则使G_1期细胞增加,S期细胞减少。高表达CaM使细胞分裂指数提高,G_2期细胞减少,有丝分裂前期细胞增加,M中期细胞比例下降。而TFP处理则使分裂指数下降,G_2期细胞增加,M前期细胞减少,M中期细胞增加。实验结果表明CaM在G_1/S、G_2/M和M中期/M后期3个位点上对细胞周期进行调控;通过加速G_1至S期,G_2至M期和M中期至M后期的进程,使细胞倍增时间缩短,促进细胞增殖。本工作表明,RC3细胞作为CaM表达可调细胞模型,是研究细胞周期调控的有力工具。 相似文献
106.
在长白山地区以红皮云杉、樟子松为材料,研究其冬季光合能力的变化,探讨了除红松外的其它针叶树是否在冬季也存在光合抑制以及遮荫是否可减轻抑制等问题,结果表明,红皮云杉、樟子松有与红松相似的冬季光合抑制,但程度较轻;遮荫对减轻光合抑制非常有效,可以推测,在长白山地区或冬季气候与之相似的地区,常绿针叶树在冬季均可能表现光合抑制,遭受冬季光氧化伤害,并且其释放的CO2(光越强,释放量越大)是空气中CO2含量 相似文献
107.
A组轮状病毒SA11VP6基因的克隆和表达 总被引:4,自引:0,他引:4
从SA11VP6基因全序列克隆开始,设计一对两端带有酶切位点的引物,逆转录PCR扩增出VP6全基因CDNA。经酶切后插入PUC19,构建了VP6全基因克隆PRA6。再经酶切后插入痘苗病毒载休质凿PJSA1175中。利用Lipofectin导入TK143细胞,利用TK基因和Lac基因作为重组病毒的筛选标记。表达产物用单克隆抗体ELISA法检测,发现细胞培养上清和细胞裂解液都是阳性。Western b 相似文献
108.
109.
温度对黄粉虫成虫繁殖的影响 总被引:2,自引:0,他引:2
黄粉虫是多种小型经济动物的常用优良饵料,本试验在20.1℃,24.0℃、28.5℃、31.7℃和36.5五种恒温下饲养该成虫结果,成虫寿命平均分别为63.0、54.2、38.8、38.0和26.1天;每雌平均产卵量则分别为200.3、207.3、122.3、115.8和81.2粒,成虫平均生产1g卵消耗麸皮量分别为2.66、2.00、2.19、2.14和4.15g。结果说明人工繁殖黄粉虫的成虫期温度以24℃为最适宜。 相似文献
110.
The vegetative morphology and life history of Halopteris filicina (Grateloup) Kutzing, collected from Korea, were examined in laboratory culture. Field plants attaining 3–5 cm in height were epilithic, tufted, yellowish-brown, and produced numerous erect axes with alternately distichous branches from compact basal discs. They were cultured under a 12:12 h LD photoperiod at 10°-C, 15°C and 20°C to observe the influence of temperature on reproduction. At 10°C plants grew only vegetatively, whereas at 15°C and 20°C they produced unilocular sporangia. Unispores released from sporangia developed into monoecious, anisogamous gametophytes that formed plurilocular female and male gametangia on the same lateral branches. The zygotes, by fusion of female macrogametes and male microgametes, developed into sporophytes bearing unilocular sporangia, whereas the unfused female gametes germinated parthenogenetically. This species was confirmed to have an isomorphic life history, basically similar to the other species of Sphacelariales. 相似文献