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991.
枇杷果实发育过程中糖积累及相关酶活性变化研究 总被引:1,自引:0,他引:1
以'青种'、'霸红'和'鸡蛋白'3个枇杷品种为材料,测定不同果实发育时期果实中蔗糖、葡萄糖和果糖含量以及蔗糖代谢相关酶即酸性转化酶(AI)、中性转化酶(NI)、蔗糖合成酶(SS)和蔗糖磷酸合成酶(SPS)的活性,并对果实中糖积累与酶活性的关系进行了分析.结果表明:在果实膨大期(5月3日)之前,3种枇杷果实的蔗糖、葡萄糖和果糖积累缓慢,之后则迅速积累,存在着明显的转折点;果实成熟(5月23日)之后糖分积累速度趋于平稳.3种枇杷果实在发育过程中转化酶、蔗糖合成酶和蔗糖磷酸合成酶的活性变化与3种糖积累的动态变化趋势相一致.NI和AI活性在果实膨大期之前都较低且没有明显的变化,之后均快速上升;SS和SPS的活性在果实膨大期之前都很低且几乎无变化,随后'鸡蛋白'的活性迅速上升至果实成熟之后便缓慢上升,而'青种'和'霸红'随果实成熟度的增加而升高,但均低于'鸡蛋白'.可见,枇杷果实膨大期是糖分积累代谢活跃期,其糖积累受蔗糖代谢相关酶综合调控. 相似文献
992.
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994.
含抑制素重组质粒的减毒猪霍乱沙门氏菌C500遗传稳定性研究 总被引:1,自引:0,他引:1
为了分析研究含抑制素重组质粒pVAX-IS-asd(以下简写为pXAIS)的crp(cAMP受体蛋白)和asd(天冬氨酸β-半乳搪脱氢酶)基因双缺失猪霍乱沙门氏菌C500菌株的遗传稳定性.方法:将现有的无抗性抑制素重组表达质粒pXAIS转化入crp和asd基因双缺失猪霍乱沙门氏菌C500菌株(简称"空质粒株")中,得"含质粒株".将"含质粒株"细菌在无选择压力条件下传代培养50代.利用酶切鉴定方法,分析"含质粒株"细菌中抑制素pXA/S质粒的稳定性;利用PCR方法扩增菌株("含质粒株"和"空质粒株")保守序列中invA基因,分析各代细菌的invA基因稳定性;通过比较传代培养后各代细菌的生长图型,分析"含质粒株"细菌传代后的生长规律.结果表明,"含质粒株"细菌连续传代50次后,仍能检出pXAIS质粒和invA基因,而且生长规律与"空质粒株"没有明显差异.说明含pXAIS质粒的猪霍乱沙门氏菌crp和asd基因双缺失株具有良好的遗传稳定性. 相似文献
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996.
Zhen Zhang Enfu Hui Edwin R. Chapman Meyer B. Jackson 《Molecular biology of the cell》2009,20(24):5086-5095
The synaptic vesicle protein synaptotagmin I (Syt I) binds phosphatidylserine (PS) in a Ca2+-dependent manner. This interaction is thought to play a role in exocytosis, but its precise functions remain unclear. To determine potential roles for Syt I-PS binding, we varied the PS content in PC12 cells and liposomes and studied the effects on the kinetics of exocytosis and Syt I binding in parallel. Raising PS produced a steeply nonlinear, saturating increase in Ca2+-triggered fusion, and a graded slowing of the rate of fusion pore dilation. Ca2+-Syt I bound liposomes more tightly as PS content was raised, with a steep increase in binding at low PS, and a further gradual increase at higher PS. These two phases in the PS dependence of Ca2+-dependent Syt I binding to lipid may correspond to the two distinct and opposing kinetic effects of PS on exocytosis. PS influences exocytosis in two ways, enhancing an early step leading to fusion pore opening, and slowing a later step when fusion pores dilate. The possible relevance of these results to Ca2+-triggered Syt I binding is discussed along with other possible roles of PS. 相似文献
997.
Zhen Liu Yang Liu Huiqiang Wang Xinjian Ge Qihuang Jin Guanghui Ding Yanan Hu Ben Zhou Zhongjian Chen Xuemei Ge Baohua Zhang Xiaobo Man Qiwei Zhai 《The international journal of biochemistry & cell biology》2009,41(12):2528-2537
Protein acetylation is increasingly recognized as an important post-translational modification. Although a lot of protein acetyltransferases have been identified, a few putative acetyltransferases are yet to be studied. In this study, we identified a novel protein acetyltransferase, Patt1, which belongs to GNAT family. Patt1 exhibited histone acetyltransferase activity and auto-acetylation activity. Deletion and mutation analysis of the predicted acetyltransferase domain in Patt1 showed that the conserved Glu139 was an important residue for its protein acetyltransferase activity. Furthermore, we found that Patt1 was highly expressed in liver and significantly downregulated in hepatocellular carcinoma tissues. In addition, we showed that overexpression of Patt1 enhanced the apoptosis of hepatoma cells dependent on its acetyltransferase activity, whereas knockdown of Patt1 significantly protected Chang liver cells from apoptosis. These data suggest that Patt1 might be involved in the development of hepatocellular carcinoma, and could be served as a potential therapy target for hepatocellular carcinoma. 相似文献
998.
Investigation of bathymetry and water quality of Lake Nam Co, the largest lake on the central Tibetan Plateau, China 总被引:3,自引:0,他引:3
Junbo Wang Liping Zhu Gerhard Daut Jianting Ju Xiao Lin Yong Wang Xiaolin Zhen 《Limnology》2009,10(2):149-158
Comprehensive field investigations have been conducted four times on Nam Co, central Tibet, from September 2005 to September
2008. Here, we present the preliminary results focusing on the bathymetric survey and water quality measurements. The isobathic
map shows that Nam Co is a high-altitude, deep lake where a flat and large basin lies in the central part with a water depth
of more than 90 m. Water depth data from the northwestern bank areas of Nam Co provide unquestionable evidence of rising water
levels in the last 3 decades because of the formation of two small islands that were still peninsulas in the 1970s. Water
quality measurements taken at 19 stations during three summer field campaigns (2006, 2007 and 2008) covering almost all of
the lake areas showed that the temperature, pH, dissolved oxygen and electric conductivity of surface water are on average
11.43°C, 9.21, 8.90 mg l−1 and 1,851 μS cm−1, respectively. The surface water shows no obvious spatial variability among all the stations. Vertical fluctuations of profiles,
however, display some differences in thermocline and related parameters, such as pH and dissolved oxygen. According to the
vertical variations of water quality parameters, the water column in relatively deep lake areas of Nam Co could be divided
into three layers with distinctly various features: the epilimnion is from the surface to about 18–20 m depth in which the
parameters are homogeneous with higher temperature and abundant sunlight; the metalimnion ranged from 20–60 m where a thermocline
develops; the deepest layer forms a cold and dark hypolimnion. 相似文献
999.
布鲁氏菌BP26基因标记疫苗株的构建及鉴别PCR方法的建立 总被引:2,自引:0,他引:2
[目的]由于现有的减毒活疫苗仍存在较强的毒力,因抗原与毒株的差异不大而很难区分疫苗免疫和自然感染等缺点,限制了现有布鲁氏菌减毒活疫苗的广泛应用.本文拟对布鲁氏菌的减毒活疫苗株M5进行遗传改造,克服这些缺点.[方法]本研究利用同源重组的方法,用卡那抗性基因替换了布鲁氏菌减毒疫苗株M5的BP26基因,得到了新的标记疫苗株M5△BP26.分别用标记疫苗株和野生株侵染巨噬细胞和感染小鼠,比较分析标记株在细胞内和小鼠体内的存活能力.根据种特异性保守基因dnaK和缺失的BP26基因设计引物,建立双重PCR,用于区分标记株与野生株.[结果]成功构建了.BP26基因标记疫苗株,细胞实验和动物实验结果表明,标记株仍能在胞内和小鼠内存活,具备作为减毒活疫苗的特性.小鼠实验结果显示,感染后两周野生株的细菌数为1022.9 ,而突变株为101.1 (P<0.01),至第3周野生株的细菌数为102.2 ,而突变株未能检出,表明与原疫苗株相比,标记株的感染力进一步减弱.根据DNA序列的差异,建立了能够区分标记疫苗株与野生株的双重PCR方法,标记株因只能扩增出一条带而能与野生株和毒株相区分,从而可以区分自然感染和疫苗免疫.[结论]基因标记疫苗株的构建及鉴别PCR方法的建立,为布鲁氏菌疫苗的进一步研发奠定了基础. 相似文献
1000.