全文获取类型
收费全文 | 712篇 |
免费 | 69篇 |
国内免费 | 2篇 |
出版年
2023年 | 14篇 |
2022年 | 7篇 |
2021年 | 46篇 |
2020年 | 19篇 |
2019年 | 24篇 |
2018年 | 25篇 |
2017年 | 21篇 |
2016年 | 31篇 |
2015年 | 64篇 |
2014年 | 58篇 |
2013年 | 47篇 |
2012年 | 75篇 |
2011年 | 52篇 |
2010年 | 28篇 |
2009年 | 34篇 |
2008年 | 30篇 |
2007年 | 34篇 |
2006年 | 28篇 |
2005年 | 16篇 |
2004年 | 17篇 |
2003年 | 21篇 |
2002年 | 15篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1992年 | 3篇 |
1980年 | 2篇 |
1976年 | 2篇 |
1968年 | 5篇 |
1967年 | 2篇 |
1958年 | 1篇 |
1957年 | 1篇 |
1955年 | 1篇 |
1954年 | 1篇 |
1949年 | 1篇 |
1948年 | 1篇 |
1939年 | 1篇 |
1936年 | 1篇 |
1934年 | 1篇 |
1933年 | 1篇 |
1932年 | 2篇 |
1929年 | 2篇 |
1928年 | 1篇 |
1926年 | 1篇 |
1924年 | 1篇 |
1922年 | 1篇 |
1911年 | 3篇 |
排序方式: 共有783条查询结果,搜索用时 265 毫秒
751.
752.
Maximilian Kmenta Katharina Bastl Siegfried Jäger Uwe Berger 《International journal of biometeorology》2014,58(8):1721-1726
Pollen allergies affect a large part of the European population and are considered likely to increase. User feedback indicates that there are difficulties in providing proper information and valid forecasts using traditional methods of aerobiology due to a variety of factors. Allergen content, pollen loads, and pollen allergy symptoms vary per region and year. The first steps in challenging such issues have already been undertaken. A personalized pollen-related symptom forecast is thought to be a possible answer. However, attempts made thus far have not led to an improvement in daily forecasting procedures. This study describes a model that was launched in 2013 in Austria to provide the first available personal pollen information. This system includes innovative forecast models using bi-hourly pollen data, traditional pollen forecasts based on historical data, meteorological data, and recent symptom data from the patient’s hayfever diary. Furthermore, it calculates the personal symptom load in real time, in particular, the entries of the previous 5 days, to classify users. The personal pollen information was made available in Austria on the Austrian pollen information website and via a mobile pollen application, described herein for the first time. It is supposed that the inclusion of personal symptoms will lead to major improvements in pollen information concerning hay fever sufferers. 相似文献
753.
Johannes Hengelbrock Johannes Rauh Jona Cederbaum Maximilian Kähler Michael Höhle 《Biometrics》2023,79(3):2757-2769
For evaluating the quality of care provided by hospitals, special interest lies in the identification of performance outliers. The classification of healthcare providers as outliers or non-outliers is a decision under uncertainty, because the true quality is unknown and can only be inferred from an observed result of a quality indicator. We propose to embed the classification of healthcare providers into a Bayesian decision theoretical framework that enables the derivation of optimal decision rules with respect to the expected decision consequences. We propose paradigmatic utility functions for two typical purposes of hospital profiling: the external reporting of healthcare quality and the initiation of change in care delivery. We make use of funnel plots to illustrate and compare the resulting optimal decision rules and argue that sensitivity and specificity of the resulting decision rules should be analyzed. We then apply the proposed methodology to the area of hip replacement surgeries by analyzing data from 1,277 hospitals in Germany which performed over 180,000 such procedures in 2017. Our setting illustrates that the classification of outliers can be highly dependent upon the underlying utilities. We conclude that analyzing the classification of hospitals as a decision theoretic problem helps to derive transparent and justifiable decision rules. The methodology for classifying quality indicator results is implemented in an R package (iqtigbdt) and is available on GitHub. 相似文献
754.
Maximilian Mora Annett Bellack Matthias Ugele Johann Hopf Reinhard Wirth 《Applied and environmental microbiology》2014,80(15):4764-4770
To date, the behavior of hyperthermophilic microorganisms in their biotope has been studied only to a limited degree; this is especially true for motility. One reason for this lack of knowledge is the requirement for high-temperature microscopy—combined, in most cases, with the need for observations under strictly anaerobic conditions—for such studies. We have developed a custom-made, low-budget device that, for the first time, allows analyses in temperature gradients up to 40°C over a distance of just 2 cm (a biotope-relevant distance) with heating rates up to ∼5°C/s. Our temperature gradient-forming device can convert any upright light microscope into one that works at temperatures as high as 110°C. Data obtained by use of this apparatus show how very well hyperthermophiles are adapted to their biotope: they can react within seconds to elevated temperatures by starting motility—even after 9 months of storage in the cold. Using the temperature gradient-forming device, we determined the temperature ranges for swimming, and the swimming speeds, of 15 selected species of the genus Thermococcus within a few months, related these findings to the presence of cell surface appendages, and obtained the first evidence for thermotaxis in Archaea. 相似文献
755.
756.
757.
758.
759.
Raphael Bereiter Maximilian Himmelstoß Eva Renard Elisabeth Mairhofer Michaela Egger Kathrin Breuker Christoph Kreutz Eric Ennifar Ronald Micura 《Nucleic acids research》2021,49(8):4281
Deazapurine nucleosides such as 3-deazaadenosine (c3A) are crucial for atomic mutagenesis studies of functional RNAs. They were the key for our current mechanistic understanding of ribosomal peptide bond formation and of phosphodiester cleavage in recently discovered small ribozymes, such as twister and pistol RNAs. Here, we present a comprehensive study on the impact of c3A and the thus far underinvestigated 3-deazaguanosine (c3G) on RNA properties. We found that these nucleosides can decrease thermodynamic stability of base pairing to a significant extent. The effects are much more pronounced for 3-deazapurine nucleosides compared to their constitutional isomers of 7-deazapurine nucleosides (c7G, c7A). We furthermore investigated base pair opening dynamics by solution NMR spectroscopy and revealed significantly enhanced imino proton exchange rates. Additionally, we solved the X-ray structure of a c3A-modified RNA and visualized the hydration pattern of the minor groove. Importantly, the characteristic water molecule that is hydrogen-bonded to the purine N3 atom and always observed in a natural double helix is lacking in the 3-deazapurine-modified counterpart. Both, the findings by NMR and X-ray crystallographic methods hence provide a rationale for the reduced pairing strength. Taken together, our comparative study is a first major step towards a comprehensive understanding of this important class of nucleoside modifications. 相似文献
760.
Some like it hot – and spicy: Chili and the capsaicin receptor TRPV1 Since many hundred years, many people like to eat chili pepper containing the pungent ingredient capsaicin that is responsible for making the food hot and spicy. Capsaicin activates transient receptor potential TRPV1 channels that are predominantly expressed in sensory neurons involved in pain sensation. TRPV1 is a noxious heat sensor and can also be activated by protons and several animal toxins. Thus, TRPV1 is a polymodal sensor of multiple noxious stimuli that cause pain. TRPV1 functions as a nocisensor that detects chemical and thermal stimuli and transduces this stimulation into sensory nerve impulses which leads to the perception of pain. Inhibition of TRPV1 reduces or abolishes pain sensation. A strong activation of TRPV1 induces a long-lasting refractory period of the pain-detecting system (desensitization) and may even lead to an irreversible loss of TRPV1-expressing sensory neurons. It still remains unclear why many people love hot and spicy food, accompanied by a burning sensation in the mouth. 相似文献