全文获取类型
收费全文 | 2496篇 |
免费 | 50篇 |
国内免费 | 27篇 |
专业分类
化学 | 1669篇 |
晶体学 | 20篇 |
力学 | 27篇 |
数学 | 553篇 |
物理学 | 283篇 |
综合类 | 21篇 |
出版年
2022年 | 36篇 |
2021年 | 51篇 |
2020年 | 25篇 |
2019年 | 35篇 |
2018年 | 29篇 |
2017年 | 34篇 |
2016年 | 61篇 |
2015年 | 51篇 |
2014年 | 68篇 |
2013年 | 133篇 |
2012年 | 121篇 |
2011年 | 112篇 |
2010年 | 77篇 |
2009年 | 59篇 |
2008年 | 97篇 |
2007年 | 127篇 |
2006年 | 117篇 |
2005年 | 95篇 |
2004年 | 98篇 |
2003年 | 64篇 |
2002年 | 73篇 |
2001年 | 45篇 |
2000年 | 34篇 |
1999年 | 28篇 |
1998年 | 27篇 |
1997年 | 32篇 |
1996年 | 37篇 |
1995年 | 32篇 |
1994年 | 30篇 |
1993年 | 36篇 |
1992年 | 39篇 |
1991年 | 31篇 |
1990年 | 36篇 |
1989年 | 38篇 |
1988年 | 16篇 |
1987年 | 26篇 |
1986年 | 15篇 |
1985年 | 30篇 |
1984年 | 34篇 |
1983年 | 21篇 |
1982年 | 23篇 |
1981年 | 37篇 |
1980年 | 21篇 |
1979年 | 27篇 |
1978年 | 27篇 |
1977年 | 28篇 |
1976年 | 21篇 |
1975年 | 18篇 |
1974年 | 17篇 |
1973年 | 18篇 |
排序方式: 共有2573条查询结果,搜索用时 15 毫秒
61.
Ernest Z. Manson Kyama C. Mutinda Joseph K. Gikunju Aleksandra Bocian Konrad K. Hus Vladimír Petrílla Jaroslav Legth James H. Kimotho 《Molecules (Basel, Switzerland)》2022,27(3)
The administration of toxin-specific therapy in snake envenoming is predicated on improved diagnostic techniques capable of detecting specific venom toxins. Various serological tests have been used in detecting snakebite envenoming. Comparatively, enzyme-linked immunosorbent assay (ELISA) has been shown to offer a wider practical application. We report an inhibition ELISA for detecting three-finger toxin (3FTx) proteins in venoms of African spitting cobras. The optimized assay detected 3FTxs in N. ashei (including other Naja sp.) venoms, spiked samples, and venom-challenged mice samples. In venoms of Naja sp., the assay showed inhibition, implying the detection of 3FTxs, but showed little or no inhibition in non-Naja sp. In mice-spiked samples, one-way ANOVA results showed that the observed inhibition was not statistically significant between spiked samples and negative control (p-value = 0.164). Similarly, the observed differences in inhibition between venom-challenged and negative control samples were not statistically significant (p-value = 0.9109). At an LOD of 0.01 µg/mL, the assay was able to confirm the presence of 3FTxs in the samples. Our results show a proof of concept for the use of an inhibition ELISA model as a tool for detecting 3FTxs in the venoms of African spitting cobra snakes. 相似文献
62.
Simple-structured, well-functioned disposable poly(dimethylsiloxane) (PDMS) microchips were developed for capillary isoelectric focusing with whole column imaging detection (CIEF-WCID). Side-by-side comparison of the developed microchips with well-established commercial capillary cartridges demonstrated that the disposable microchips have comparable performance as well as advantages such as absence of lens effect and possibility of high-aspect-ratio accompanied with a dramatic reduction in cost. 相似文献
63.
Aleksandra Stegliska Anastasiia Bekhter Pawe Wawrzyniak Alina Kunicka-Styczyska Konrad Jastrzbek Micha Fidler Krzysztof
migielski Beata Gutarowska 《Molecules (Basel, Switzerland)》2022,27(5)
The purpose of the study was to select an environmentally friendly plant biopesticide to protect seed potatoes against phytopathogens. The scope included the evaluation of the antimicrobial activities of 22 plant water extracts, 22 water-glycol extracts, and 3 subcritical carbon dioxide extracts using the agar diffusion method against 10 potato phytopathogens. For the most effective extracts, minimal inhibitory concentration (MIC), chemical composition analysis by gas chromatography–mass spectrometry and in situ assays on seed potatoes were performed. Garlic water extract was finally selected as the most effective in phytopathogen growth inhibition, both in vitro and in situ, with MIC values ranging between 6.3–25 mg/mL. 5-Hydroxymethylfurfural was determined to be the main component of this extract (33.24%). Garlic water extract was proposed as a potential biopesticide against potato phytopathogens. 相似文献
64.
We measure the content of random uncorrelated noise in heart rate variability using a general method of noise level estimation using a coarse-grained entropy. We show that usually, except for atrial fibrillation, the level of such noise is within 5-15% of the variance of the data and that the variability due to the linearly correlated processes is dominant in all cases analyzed but atrial fibrillation. The nonlinear deterministic content of heart rate variability remains significant and may not be ignored. 相似文献
65.
Konrad Knopp 《Mathematische Zeitschrift》1923,18(1):125-156
Ohne Zusammenfassung 相似文献
66.
Konrad Zindler 《Monatshefte für Mathematik》1923,33(1):31-36
Ohne Zusammenfassung 相似文献
67.
Konrad Schumacher 《Journal of Mathematical Analysis and Applications》1981,80(1):261-290
In this paper we will be concerned with the abstract semilinear equation x(Φ)(t) = Ax(Φ)(t) + F(t, xt(Φ)), t ? τ, xτ(Φ) = Φ, where A represents the infinitesimal generator of a linear C0-semigroup in a Banach space and x~(Φ) denotes the segment of the solution x due to the initial function Φ taken from ?∞ up to t. Conditions for existence, continuous dependence, and regularity of solutions are given which are independent of the topology of the phase space, as well as conditions which guarantee the compactness of bounded orbits, even if exp(At) is not compact for t > 0. 相似文献
68.
An instantaneous time series distance is defined through the equal time correlation coefficient. The idea is applied to the Gross Domestic Product (GDP) yearly increments of 21 rich countries between 1950 and 2005 in order to test the process of economic globalisation. Some data discussion is first presented to decide what (EKS, GK, or derived) GDP series should be studied. Distances are then calculated from the correlation coefficient values between pairs of series. The role of time averaging of the distances over finite size windows is discussed. Three network structures are next constructed based on the hierarchy of distances. It is shown that the mean distance between the most developed countries on several networks actually decreases in time, —which we consider as a proof of globalization. An empirical law is found for the evolution after 1990, similar to that found in flux creep. The optimal observation time window size is found ?15 years. 相似文献
69.
We study extremality in various sets of states that have positive partial transposes. One of the tools we use for this purpose is the recently formulated criterion allowing to judge if a given state is extremal in the set of PPT states. First we investigate qubit-ququart states and show that the only candidates for extremal PPT entangled states (PPTES) have ranks of the state and its partial transposition (5, 5) or (5, 6) (equivalently (6, 5)). Then, examples of extremal states of (5, 5) type and the so-called edge states of type (5, 6) are provided. We also make an attempt to explore the set of PPT states with ranks (5, 6). Finally, we discuss what are the possible configurations of ranks of density matrices and their respective partial transposition in general three-qubit and four-qubit symmetric states for which there may exist extremal entangled PPT states. For instance in the first case we show that the only possibilities are (4, 4, 4) and (4, 4, 5). 相似文献
70.
The economy globalization measure problem is discussed. Four macroeconomic indices of twenty among the “richest” countries are examined. Four types of “distances” are calculated. Two types of networks are next constructed for each distance measure definition. It is shown that the globalization process can be best characterised by an entropy measure, based on entropy Manhattan distance. It is observed that a globalization maximum was reached during the interval 1970-2000. More recently a deglobalization process has been observed. 相似文献