全文获取类型
收费全文 | 33940篇 |
免费 | 3052篇 |
国内免费 | 2476篇 |
专业分类
39468篇 |
出版年
2024年 | 89篇 |
2023年 | 418篇 |
2022年 | 813篇 |
2021年 | 1326篇 |
2020年 | 963篇 |
2019年 | 1181篇 |
2018年 | 1158篇 |
2017年 | 797篇 |
2016年 | 1193篇 |
2015年 | 2021篇 |
2014年 | 2247篇 |
2013年 | 2492篇 |
2012年 | 3037篇 |
2011年 | 2831篇 |
2010年 | 1691篇 |
2009年 | 1505篇 |
2008年 | 1832篇 |
2007年 | 1645篇 |
2006年 | 1505篇 |
2005年 | 1238篇 |
2004年 | 1155篇 |
2003年 | 985篇 |
2002年 | 892篇 |
2001年 | 719篇 |
2000年 | 657篇 |
1999年 | 586篇 |
1998年 | 326篇 |
1997年 | 314篇 |
1996年 | 297篇 |
1995年 | 248篇 |
1994年 | 265篇 |
1993年 | 180篇 |
1992年 | 320篇 |
1991年 | 295篇 |
1990年 | 246篇 |
1989年 | 229篇 |
1988年 | 192篇 |
1987年 | 156篇 |
1986年 | 146篇 |
1985年 | 151篇 |
1984年 | 142篇 |
1983年 | 103篇 |
1982年 | 90篇 |
1980年 | 59篇 |
1979年 | 75篇 |
1978年 | 69篇 |
1977年 | 58篇 |
1976年 | 67篇 |
1975年 | 63篇 |
1974年 | 75篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Lin Xiang Lin Shuang Liu Yuanlan Zhao Haiyan Wang Li Hasi Wuliji 《Plasmonics (Norwell, Mass.)》2018,13(5):1749-1758
Plasmonics - Large-scale ordered two-dimensional (2D) superlattices at oil/water interface were fabricated using single-crystal Au nanospheres (NSs) with different diameters as building blocks. A... 相似文献
992.
993.
Quick and reliable testing of EGFR and KRAS is needed in non-small cell lung cancer (NSCLC) to ensure optimal decision-making for targeted therapy. The Idylla™ platform was designed for Formalin-Fixed Paraffin-Embedded (FFPE) tissue sections but recently several studies were published that evaluated its potential for cytological specimens. This study aimed to validate the Idylla™ platform for the detection of EGFR/KRAS mutations in cytological NSCLC samples prepared as cytoblocks using AGAR and paraffin embedding. The KRAS Idylla™ test were performed on 11 specimens with a known KRAS mutation. The EGFR Idylla™ test was performed on 18 specimens with a known primary EGFR mutation and 7 specimens with a primary EGFR-EGFR T790M resistance mutation combination. Concordant KRAS and primary EGFR mutations were detected for both KRAS and primary EGFR mutations. Samples with a total CQ value of < 26 could be considered negative. Samples with a total CQ value of > 26 could not be assessed (probability of false-negative). In specimens with a primary EGFR-EGFR T790M resistance mutation combination, 5/7 cases were not concordant. Our results confirm the conclusion of recent reports that the Idylla™EGFR assay is not suitable in a resistance to EGFR TKI setting, also not in our cytological NSCLC samples prepared as cytoblocks using AGAR and paraffin embedding. KRAS and primary EGFR mutations were detected using the Idylla™ assays in virtually all cytological NSCLC samples. This analysis was rapid and time-saving compared to other mutation detection assays and may be useful if the amount of material is insufficient to perform a full set of molecular tests. 相似文献
994.
Huang SY Tang JD Song HQ Fu BQ Xu MJ Hu XC Zhang H Weng YB Lin RQ Zhu XQ 《Parasitology international》2012,61(1):187-190
Clonorchiasis caused by Clonorchis sinensis is a fish-borne parasitic disease which is endemic in a number of countries. Using the sequences of the internal transcribed spacers (ITS-1 and ITS-2) of nuclear ribosomal DNA (rDNA) of C. sinensis as genetic markers, a pair of C. sinensis-specific primers was designed and used to establish a specific PCR assay for the diagnosis of C. sinensis infection in humans, cats and fish. This approach allowed the specific identification of C. sinensis after optimizing amplification conditions, with no amplicons being amplified from related heterogeneous DNA samples, and sequencing of amplicons confirmed the identity of the sequences amplified. The detection limit of this assay was 1.03 pg of adult C. sinensis, 1.1 metacercariae per gram of fish filet, and a single egg in human and cat feces. The PCR assay should provide a useful tool for the diagnosis and molecular epidemiological investigation of clonorchiasis in humans and animals. 相似文献
995.
The identification of functional gene modules that are derived from integration of information from different types of networks is a powerful strategy for interpreting the etiology of complex diseases such as rheumatoid arthritis (RA). Genetic variants are known to increase the risk of developing RA. Here, a novel method, the construction of a genetic network, was used to mine functional gene modules linked with RA. A polymorphism interaction analy-sis (PIA) algorithm was used to obtain cooperating single nucleotide polymorphisms (SNPs) that contribute to RA disease. The acquired SNP pairs were used to construct a SNP-SNP network. Sub-networks defined by hub SNPs were then extracted and turned into gene modules by mapping SNPs to genes using dbSNP database. We per-formed Gene Ontology (GO) analysis on each gene module, and some GO terms enriched in the gene modules can be used to investigate clustered gene function for better understanding RA pathogenesis. This method was applied to the Genetic Analysis Workshop 15 (GAW 15) RA dataset. The results show that genes involved in func-tional gene modules, such as CD160 (rs744877) and RUNX1 (rs2051179), are especially relevant to RA, which is supported by previous reports. Furthermore, the 43 SNPs involved in the identified gene modules were found to be the best classifiers when used as variables for sample classification. 相似文献
996.
Principles and approach to developing mammalian cell culture media for high cell density perfusion process leveraging established fed‐batch media 下载免费PDF全文
Henry Lin Robert Woodrow Leighty Scott Godfrey Samantha Boran Wang 《Biotechnology progress》2017,33(4):891-901
Perfusion medium was successfully developed based on our fed‐batch platform basal and feed media. A systematic development approach was undertaken by first optimizing the ratios of fed‐batch basal and feed media followed by targeted removal of unnecessary and redundant components. With this reduction in components, the medium could then be further concentrated by 2× to increase medium depth. The medium osmolality was also optimized where we found ~360 mOsm/kg was desirable resulting in a residual culture osmolality of ~300 mOsm/kg for our cell lines. Further building on this, the amino acids Q, E, N, and D were rebalanced to reduce lactate and ammonium levels, and increase the cell‐specific productivity without compromising on cell viability while leaving viable cell density largely unaffected. Further modifications were also made by increasing certain important vitamin and lipid concentrations, while eliminating other unnecessary vitamins. Overall, an effective perfusion medium was developed with all components remaining in the formulation understood to be important and their concentrations increased to improve medium depth. The critical cell‐specific perfusion rate using this medium was then established for a cell line of interest to be 0.075 nL/cell‐day yielding 1.2 g/L‐day at steady state. This perfusion process was then successfully scaled up to a 100 L single‐use bioreactor with an ATF6 demonstrating similar performance as a 2 L bioreactor with an ATF2. Large volume handling challenges in our fed‐batch facility were overcome by developing a liquid medium version of the powder medium product contained in custom totes for plug‐and‐play use with the bioreactor. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:891–901, 2017 相似文献
997.
I.-Wu Chen Juinn H. Lin Joan Dorley 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1992,576(2)
A high-performance liquid chromatographic (HPLC) procedure has been developed for the quantification of L-365,260 (I), a cholecystokinin and gastrin receptor antagonist, in dog and rat plasma. The method involves liquid—liquid extraction and HPLC with ultraviolet detection. Standard curves were linear over the range 7.5–2000 ng/ml for rat and dog plasma. The method is reproducible and reliable with a detection limit of 7.5 ng/ml in biological fluids. The mean coefficients of variation for concentrations within the range of the standard curve range were 3.84 and 2.56%, respectively, for intra-day analysis and 4.48 and 4.26%, respectively, for inter-day analysis. Application of the development was successfully demonstrated by quantifying the concentration of I in both dog and rat plasma samples following an intravenous or oral dose of 5 mg/kg I. 相似文献
998.
999.
1000.
Here, we report a novel porcine circovirus type 2a (PCV2a) strain with 11 nucleotides (nt) inserted in the origin of genome replication (Ori). This is the first report of a PCV2a strain with nucleotide insertion in Ori. Our study will help further epidemiological studies and extend our knowledge of evolutionary characteristics of PCV2. 相似文献