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991.
992.
目的:建立快速简便检测青蒿素的超高效液相-紫外(UPLC-UV)法,并对不同产地青蒿中青蒿素的含量进行检测。方法:色谱柱Agilent Eclipse Plus C18(2.1 mm×50 mm,1.8μm),流动相乙腈/水(45/55),流速1.0mL/min,柱温28℃,波长200 nm。结果:该方法对青蒿素的分离度较好,保留时间缩短为1.5 min。并且,整个分析过程可以在2 min内完成。线性范围0.101 17~10.117μg,进样量与峰面积线性相关,A=109.4C+6.7026,R2=0.9 993(n=9),加样回收率为99.3%(RSD=2.6%,n=6)。结论:UPLC-UV法分析时间短、样品前处理简单、精密度、稳定性、加样回收率等符合分析检测要求,对于青蒿中青蒿素的含量能进行快速准确的分析。 相似文献
993.
994.
郑联合王育才张云飞于哲陈翔 《现代生物医学进展》2012,12(9):1680-1682
目的:探讨个性化后侧入路治疗单纯性胫骨平台后髁冠状面骨折手术方法。方法:12例单纯性胫骨平台后髁冠状面骨折的患者,采用后内侧或后外侧以及后内后外联合入路切开复位内固定治疗。结果:12例均获随访,随访时间8-24个月,平均13个月。患者膝关节功能评定按Hohl评分标准:优10例,良2例。复查X线片:骨折复位良好,关节面未见明显塌陷。结论:个性化后侧入路治疗单纯性胫骨平台后髁骨折冠状面可直视下暴露胫骨平台后髁,提供了更广阔的操作空间,有利于骨折的解剖复位内固定。 相似文献
995.
本研究以优良杂交品种"两广二号"家蚕为试材,克隆了该杂交品种家蚕两个抗家蚕核型多角体病毒(BmNPV)基因:脂肪酶基因Bmlipase-1和丝氨酸蛋白酶基因BmSP-2,测序并分别与不同品种蚕的同源基因序列进行比较。结果显示,"两广二号"家蚕Bmlipase-1基因ORF长度为885bp,编码294个氨基酸,BmSP-2扩增长度为855bp,编码284个氨基酸;它们的核苷酸和推导氨基酸序列同源性皆达92%以上,Bmlipase-1更保守,同源性大于99%";两广二号"家蚕的Bmlipase-1基因脂肪酶活化部位和BmSP-2基因酶催化三联体位点的氨基酸残基与不同品种蚕的完全相同。以上结果说明这两个抗病毒基因在蚕的遗传进化过程中高度保守,提示其可能在机体消化或者免疫防御方面起着重要生理作用。将这两个抗病毒基因在大肠杆菌BL21中进行融合表达,获得的融合Bmlipase-1和BmSP-2蛋白分子量分别为47kD和42kD左右。 相似文献
996.
We developed a colorimetric assay to quantify clavulanic acid (CA) in culture broth of Streptomyces clavuligerus, to facilitate screening of a large number of S. clavuligerus mutants. The assay is based on a β-lactamase-catalyzed reaction, in which the yellow substrate nitrocefin (λ
max=390 nm) is converted to a red product (λ
max=486 nm). Since CA can irreversibly inhibit β-lactamase activity, the level of CA in a sample can be measured as a function
of the A
390/A
486 ratio in the assay mixture. The sensitivity and detection window of the assay were determined to be 50 μg L−1 and 50 μg L−1 to 10 mg L−1, respectively. The reliability of the assay was confirmed by comparing assay results with those obtained by HPLC. The assay
was used to screen a pool of 65 S. clavuligerus mutants and was reliable for identifying CA over-producing mutants. Therefore, the assay saves time and labor in large-scale
mutant screening and evaluation tasks. The detection window and the reliability of this assay are markedly better than those
of previously reported CA assays. This assay method is suitable for high throughput screening of microbial samples and allows
direct visual observation of CA levels on agar plates. 相似文献
997.
Jing Yang XiaYu Xia Xiang He SenLin Yang YuHua Ruan QuanBi Zhao ZhiXin Wang YiMing Shao XianMing Pan 《中国科学:生命科学英文版》2012,55(4):328-335
The long asymptomatic stage of HIV infection poses a great challenge in identifying recent HIV infections. This is a bottleneck
for monitoring HIV epidemic trends and evaluating the effectiveness of national AIDS control programs. Several serological
methods were used to address this issue with some success. Because of high false-positive rates in patients with advanced
infection or in ART treatment, UNAIDS still hesitates to recommend their use in routine surveillance. We developed a new pattern-based
method for measuring intra-patient viral genetic diversity for determination of recent infections and estimation of population
incidence. This method is verified by using several datasets (424 subtype B and 77 CRF07_BC samples) with clearly identified
HIV-1 infection times. Pattern-based diversities of recent infections are significantly lower than that of chronic ones. With
larger window periods varying from 200 to 350 days, a higher accuracy (90%–95%) not affected by advanced disease nor ART treatment
could be obtained. The pattern-based genetic method is supplementary to the existing serology-based assays, both of which
could be suitable for use in low and high epidemic regions, respectively. 相似文献
998.
HouZao Chen YanZhen Wan Shuang Zhou YunBiao Lu ZhuQin Zhang Ran Zhang Feng Chen DeLong Hao Xiang Zhao ZhiChen Guo DePei Liu ChihChuan Liang 《中国科学:生命科学英文版》2012,55(6):467-473
The rapidly increasing prevalence of diabetes mellitus worldwide is one of the most serious and challenging health problems in the 21st century. Mammalian sirtuin 1 (SIRT1) has been shown to decrease high-glucose-induced endothelial cell senescence in vitro and prevent hyperglycemia-induced vascular dysfunction. However, a role for SIRT1 in prevention of hyperglycemia-induced vascular cell senescence in vivo remains unclear. We used endothelium-specific SIRT1 transgenic (SIRT1-Tg) mice and wild-type (WT) mice to construct a 40-week streptozotocin (STZ)-induced diabetic mouse model. In this mode, 42.9% of wild-type (WT) mice and 38.5% of SIRT1-Tg mice were successfully established as diabetic. Forty weeks of hyperglycemia induced significant vascular cell senescence in aortas of mice, as indicated by upregulation of expression of senescence-associated markers including p53, p21 and plasminogen activator inhibitor-1 (PAI-1). However, SIRT1-Tg diabetic mice displayed dramatically decreased expression of p53, p21 and PAI-1 compared with diabetic WT mice. Moreover, manganese superoxide dismutase expression (MnSOD) was significantly downregulated in the aortas of diabetic WT mice, but was preserved in diabetic SIRT1-Tg mice. Furthermore, expression of the oxidative stress adaptor p66Shc was significantly decreased in aortas of SIRT1-Tg diabetic mice compared with WT diabetic mice. Overall, these findings suggest that SIRT1-mediated inhibition of hyperglycemia-induced vascular cell senescence is mediated at least partly through the reduction of oxidative stress. 相似文献
999.
This protocol describes a single-molecule pull-down (SiMPull) assay for analyzing physiological protein complexes. The assay combines the conventional pull-down assay with single-molecule total internal reflection fluorescence (TIRF) microscopy and allows the probing of single macromolecular complexes directly from cell or tissue extracts. In this method, antibodies against the protein of interest are immobilized on a passivated microscope slide. When cell extracts are applied, the surface-tethered antibody captures the protein together with its physiological interaction partners. After washing away the unbound components, single-molecule fluorescence microscopy is used to probe the pulled-down proteins. Captured proteins are visualized through genetically encoded fluorescent protein tags or through antibody labeling. Compared with western blot analysis, this ultrasensitive assay requires considerably less time and reagents and provides quantitative data. Furthermore, SiMPull can distinguish between multiple association states of the same protein. SiMPull is generally applicable to proteins from a variety of cellular contexts and to endogenous proteins. Starting with the cell extracts and passivated slides, the assay requires 1.5-2.5 h for data acquisition and analysis. 相似文献
1000.
The effect of calcium chloride injection on shear force and caspase activities in bovine longissimus muscles during postmortem conditioning 总被引:1,自引:0,他引:1
Cao J Yu X Khan MA Shao J Xiang Y Zhou G 《Animal : an international journal of animal bioscience》2012,6(6):1018-1022
Tenderness is considered as the most important quality determinant of meat. Calcium chloride application has been shown to improve tenderness by regulating endogenous proteinases. This study was designed to determine the effect of 300 mM calcium chloride injection on myofibrillar structures, caspase activities and shear force in longissimus muscles of bulls during postmortem storage of 7 days. Myofibrillar fragmentation index was determined as an index of proteolysis occurring in muscle fibers and associated proteins. Maximum tenderness was observed at days 4 and 7 in both treated and control samples. The injection of calcium chloride significantly increased myofibrillar proteolysis and improved tenderness at postmortem days 4 and 7. The treatment reduced caspase-9 activity at 4 h and day 4, whereas those of caspase-8 and -3 activities at days 1 and 4 with respect to control. The improved tenderness and increased myofibril fragmentation with decreased caspase activities suggested that the proteolytic systems activated with calcium chloride injection possibly behave independent of the caspase system. 相似文献