全文获取类型
收费全文 | 23726篇 |
免费 | 2023篇 |
国内免费 | 14篇 |
出版年
2023年 | 79篇 |
2021年 | 361篇 |
2020年 | 254篇 |
2019年 | 344篇 |
2018年 | 415篇 |
2017年 | 393篇 |
2016年 | 621篇 |
2015年 | 1038篇 |
2014年 | 1184篇 |
2013年 | 1494篇 |
2012年 | 1682篇 |
2011年 | 1601篇 |
2010年 | 1041篇 |
2009年 | 967篇 |
2008年 | 1288篇 |
2007年 | 1213篇 |
2006年 | 1223篇 |
2005年 | 1183篇 |
2004年 | 1115篇 |
2003年 | 968篇 |
2002年 | 1027篇 |
2001年 | 377篇 |
2000年 | 315篇 |
1999年 | 325篇 |
1998年 | 294篇 |
1997年 | 230篇 |
1996年 | 249篇 |
1995年 | 241篇 |
1994年 | 245篇 |
1993年 | 249篇 |
1992年 | 252篇 |
1991年 | 220篇 |
1990年 | 194篇 |
1989年 | 194篇 |
1988年 | 183篇 |
1987年 | 173篇 |
1986年 | 145篇 |
1985年 | 179篇 |
1984年 | 200篇 |
1983年 | 169篇 |
1982年 | 180篇 |
1981年 | 147篇 |
1980年 | 128篇 |
1979年 | 132篇 |
1978年 | 121篇 |
1977年 | 117篇 |
1976年 | 90篇 |
1975年 | 65篇 |
1974年 | 95篇 |
1973年 | 79篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
Jacek Kęsy Beata Maciejewska Magdalena Sowa Magdalena Szumilak Krzysztof Kawałowski Maja Borzuchowska Jan Kopcewicz 《Plant Growth Regulation》2008,55(1):43-50
It has been shown that both IAA and ethylene application inhibit flower induction in the short-day plant Pharbitis nil. However application of IAA has elevated ethylene production in this plant, as well. Strong enhancement of ethylene production
is also correlated with the night-break effect, which completely inhibits flowering. In order to determine what the role of
IAA and ethylene is in the photoperiodic flower induction in Pharbitis nil, we measured changes in their levels during inductive and non-inductive photoperiods, and the effects of ethylene biosynthesis
and action inhibitors on inhibition of flowering by IAA. Our results have shown that the inhibitory effect of IAA on Pharbitis nil flowering is not physiological but is connected with its effect on ethylene biosynthesis. 相似文献
23.
Bacteriocin Release Protein Triggers Dimerization of Outer Membrane Phospholipase A In Vivo 总被引:4,自引:0,他引:4 下载免费PDF全文
Bacteriocin release protein is known to activate outer membrane phospholipase A (OMPLA), which results in the release of colicin from Escherichia coli. In vivo chemical cross-linking experiments revealed that the activation coincides with dimerization of OMPLA. Permeabilization of the cell envelope and dimerization were characterized by a lag time of 2 h. 相似文献
24.
25.
26.
Ruofan Wang Camille R. Simoneau Jessie Kulsuptrakul Mehdi Bouhaddou Katherine A. Travisano Jennifer M. Hayashi Jared Carlson-Stevermer James R. Zengel Christopher M. Richards Parinaz Fozouni Jennifer Oki Lauren Rodriguez Bastian Joehnk Keith Walcott Kevin Holden Anita Sil Jan E. Carette Nevan J. Krogan Andreas S. Puschnik 《Cell》2021,184(1):106-119.e14
27.
Ryan A. Flynn Julia A. Belk Yanyan Qi Yuki Yasumoto Jin Wei Mia Madel Alfajaro Quanming Shi Maxwell R. Mumbach Aditi Limaye Peter C. DeWeirdt Cameron O. Schmitz Kevin R. Parker Elizabeth Woo Howard Y. Chang Tamas L. Horvath Jan E. Carette Carolyn R. Bertozzi Craig B. Wilen Ansuman T. Satpathy 《Cell》2021,184(9):2394-2411.e16
28.
Agnieszka Smolinska Ester M. M. Klaassen Jan W. Dallinga Kim D. G. van de Kant Quirijn Jobsis Edwin J. C. Moonen Onno C. P. van Schayck Edward Dompeling Frederik J. van Schooten 《PloS one》2014,9(4)
Wheezing is one of the most common respiratory symptoms in preschool children under six years old. Currently, no tests are available that predict at early stage who will develop asthma and who will be a transient wheezer. Diagnostic tests of asthma are reliable in adults but the same tests are difficult to use in children, because they are invasive and require active cooperation of the patient. A non-invasive alternative is needed for children. Volatile Organic Compounds (VOCs) excreted in breath could yield such non-invasive and patient-friendly diagnostic. The aim of this study was to identify VOCs in the breath of preschool children (inclusion at age 2–4 years) that indicate preclinical asthma. For that purpose we analyzed the total array of exhaled VOCs with Gas Chromatography time of flight Mass Spectrometry of 252 children between 2 and 6 years of age. Breath samples were collected at multiple time points of each child. Each breath-o-gram contained between 300 and 500 VOCs; in total 3256 different compounds were identified across all samples. Using two multivariate methods, Random Forests and dissimilarity Partial Least Squares Discriminant Analysis, we were able to select a set of 17 VOCs which discriminated preschool asthmatic children from transient wheezing children. The correct prediction rate was equal to 80% in an independent test set. These VOCs are related to oxidative stress caused by inflammation in the lungs and consequently lipid peroxidation. In conclusion, we showed that VOCs in the exhaled breath predict the subsequent development of asthma which might guide early treatment. 相似文献
29.
30.
Ajeet Pratap Singh Rudra Nayan Das Gururaj Rao Aman Aggarwal Soeren Diegelmann Jan Felix Evers Hrishikesh Karandikar Matthias Landgraf Veronica Rodrigues K. VijayRaghavan 《PLoS genetics》2013,9(4)
Olfactory sensory neurons connect to the antennal lobe of the fly to create the primary units for processing odor cues, the glomeruli. Unique amongst antennal-lobe neurons is an identified wide-field serotonergic neuron, the contralaterally-projecting, serotonin-immunoreactive deutocerebral neuron (CSDn). The CSDn spreads its termini all over the contralateral antennal lobe, suggesting a diffuse neuromodulatory role. A closer examination, however, reveals a restricted pattern of the CSDn arborization in some glomeruli. We show that sensory neuron-derived Eph interacts with Ephrin in the CSDn, to regulate these arborizations. Behavioural analysis of animals with altered Eph-ephrin signaling and with consequent arborization defects suggests that neuromodulation requires local glomerular-specific patterning of the CSDn termini. Our results show the importance of developmental regulation of terminal arborization of even the diffuse modulatory neurons to allow them to route sensory-inputs according to the behavioural contexts. 相似文献