全文获取类型
收费全文 | 6388篇 |
免费 | 430篇 |
国内免费 | 8篇 |
出版年
2023年 | 47篇 |
2022年 | 155篇 |
2021年 | 280篇 |
2020年 | 124篇 |
2019年 | 157篇 |
2018年 | 204篇 |
2017年 | 155篇 |
2016年 | 184篇 |
2015年 | 307篇 |
2014年 | 338篇 |
2013年 | 475篇 |
2012年 | 472篇 |
2011年 | 414篇 |
2010年 | 237篇 |
2009年 | 207篇 |
2008年 | 249篇 |
2007年 | 263篇 |
2006年 | 228篇 |
2005年 | 197篇 |
2004年 | 202篇 |
2003年 | 162篇 |
2002年 | 166篇 |
2001年 | 124篇 |
2000年 | 108篇 |
1999年 | 82篇 |
1998年 | 44篇 |
1997年 | 40篇 |
1996年 | 39篇 |
1995年 | 28篇 |
1994年 | 26篇 |
1992年 | 63篇 |
1991年 | 74篇 |
1990年 | 74篇 |
1989年 | 61篇 |
1988年 | 68篇 |
1987年 | 49篇 |
1986年 | 41篇 |
1985年 | 55篇 |
1984年 | 49篇 |
1983年 | 43篇 |
1982年 | 26篇 |
1980年 | 32篇 |
1979年 | 39篇 |
1978年 | 43篇 |
1977年 | 33篇 |
1976年 | 34篇 |
1974年 | 40篇 |
1973年 | 27篇 |
1971年 | 25篇 |
1970年 | 27篇 |
排序方式: 共有6826条查询结果,搜索用时 15 毫秒
91.
Abstract: The pentameric subunit composition of a large population (36%) of the cerebellar granule cell GABAA receptors that show diazepam (or clonazepam)-insensitive [3 H]Ro 15-4513 binding has been determined by immunoprecipitation with subunit-specific antibodies. These receptors have α6 , α1 , γ2S , γ2L , and β2 or β3 subunits colocalizing in the same receptor complex. 相似文献
92.
Christina Brahe Isabella Velonà Gerrit van der Steege Stefania Zappata Anneke Y. van de Veen Jan Osinga Carli M. J. Tops Riccardo Fodde P. Meera Khan Charles H. C. M. Buys Giovanni Neri 《Human genetics》1994,93(5):494-501
The locus responsible for the childhood-onset proximal spinal muscular atrophies (SMA) has recently been mapped to an area of 2–3 Mb in the region q12–13.3 of chromosome 5. We have used a series of radiation hybrids (RHs) containing distinct parts of the SMA region as defined by reference markers. A cosmid library was constructed from one RH. Thirteen clones were isolated and five of these were mapped within the SMA region. Both RH mapping and fluorescence in situ hybridization analysis showed that two clones map in the region between loci D5S125 and D5S351. One of the cosmids contains expressed sequences. Polymorphic dinucleotide repeats were identified in both clones and used for segregation analysis of key recombinant SMA families. One recombination between the SMA locus and the new marker 9Ic (D5S685) indicates that 9Ic is probably the closest distal marker. The absence of recombination between the SMA locus and marker Fc (D5S684) suggests that Fc is located close to the disease gene. These new loci should refine linkage analysis in SMA family studies and may facilitate the isolation of the disease gene. 相似文献
93.
Citric acid production in surface culture process with reuse of mycelia for more than one batch of media has been reported in this work. A strategy for replacing media and thus increasing productivity in subsequent batches is discussed. An explanation for the decrease in citric acid accumulation beyond the second batch is suggested on the basis of oxygen limitation. 相似文献
94.
S Khan 《Journal of bacteriology》1993,175(8):2169-2174
95.
K. M. Mearow B. G. Thilander I. Khan R. E. Garfield A. K. Grover 《Molecular and cellular biochemistry》1993,121(2):155-165
Heart tissue contains large amounts of the protein encoded by the Ca2+ pump gene SERCA2. The SERCA2 RNA can be spliced alternatively to produce mRNA encoding the proteins SERCA2a and SERCA2b which differ in their C-terminal sequences. In this study we report the tissue distribution of SERCA2a and SERCA2b isoforms byin situ hybridization to rabbit heart and stomach. The expression of SERCA2 mRNA was high in myocardial cells, being the highest in the atrial region. In contrast, there was more SERCA2 protein in Western blots in ventricles than in atria. Myocardial cells expressed predominantly the mRNA for the isoform SERCA2a. Whereas the stomach smooth muscle and the neuronal plexus expressed SERCA2 at levels much lower than myocardial cells, the expression was very high in the stomach mucosa. Mucosa contained mainly the mRNA for SERCA2b. From immunocytochemistry it was concluded that the anti-heart SR Ca2+ pump antibody IID8 reacted much better with heart and surface mucosal cells in the stomach than with the stomach smooth muscle, and that IID8 reactivity was intracellular. In contrast PM4A2B, an antibody against the plasma membrane Ca2+ pump, reacted well with heart and stomach smooth muscle, plexus and mucosa, and its localization appeared to be in the plasma membrane. Thus, stomach smooth muscle expressed SERCA2b mRNA and protein at low levels, mucosa expressed SERCA2b mRNA and protein at high levels, atria and ventricle expressed SERCA2a mRNA and protein at high levels, mRNA being more in atria, but protein being more in ventricles.Deceased August 14, 1992 相似文献
96.
97.
E. J. Breslau-Siderius J. Th. Wijnen J. G. Dauwerse J. M. de Pater F. A. Beemer P. Meera Khan 《Human genetics》1993,92(5):481-485
A de novo duplication of the proximal part of the long arms of chromosome 5 was found in a male born with craniostenosis, ear tags and kidney dysplasia. The nature of the chromosomal aberration was defined by fluorescence in situ hybridization and the orgin of the duplication was traced by polymorphic DNA markers. A comparison is made with the published cases showing similar duplications in the long arm of chromosome 5. 相似文献
98.
99.
Aamir Hamid Khan Ling Min Yizan Ma Muhammad Zeeshan Shuangxia Jin Xianlong Zhang 《Plant biotechnology journal》2023,21(4):680-697
Global food security is one of the utmost essential challenges in the 21st century in providing enough food for the growing population while coping with the already stressed environment. High temperature (HT) is one of the main factors affecting plant growth, development and reproduction and causes male sterility in plants. In male reproductive tissues, metabolic changes induced by HT involve carbohydrates, lipids, hormones, epigenetics and reactive oxygen species, leading to male sterility and ultimately reducing yield. Understanding the mechanism and genes involved in these pathways during the HT stress response will provide a new path to improve crops by using molecular breeding and biotechnological approaches. Moreover, this review provides insight into male sterility and integrates this with suggested strategies to enhance crop tolerance under HT stress conditions at the reproductive stage. 相似文献
100.
Mohd Imran Shahzad Ahmed Ahmad Zuhairi Abdullah Jabir Hakami Anis Ahmad Chaudhary Hassan Ahmad Rudayni Salah-Ud-Din Khan Afzal Khan Nosiba Suliman Basher 《Luminescence》2023,38(7):1064-1086
The penicillin derivative amoxicillin (AMX) plays an important role in treating various types of infections caused by bacteria. However, excessive use of AMX may have negative health effects. Therefore, it is of utmost importance to detect and quantify the AMX in pharmaceutical drugs, biological fluids, and environmental samples with high sensitivity. Therefore, this review article provides valuable and up-to-date information on nanostructured material-based optical and electrochemical sensors to detect AMX in various biological and chemical samples. The role of using different nanostructured materials on the performance of important optical sensors such as colorimetric sensors, fluorescence sensors, surface-enhanced Raman scattering sensors, chemiluminescence/electroluminescence sensors, optical immunosensors, optical fibre-based sensors, and several important electrochemical sensors based on different electrode types have been discussed. Moreover, nanocomposites, polymer, and MXenes-based electrochemical sensors have also been discussed, in which such materials are being used to further enhance the sensitivity of these sensors. Furthermore, nanocomposite-based photo-electrochemical sensors and the market availability of biosensors including AMX have also been discussed briefly. Finally, the conclusion, challenges, and future perspectives of the above-mentioned sensing techniques for AMX detection are presented. 相似文献