全文获取类型
收费全文 | 509篇 |
免费 | 13篇 |
国内免费 | 2篇 |
专业分类
化学 | 350篇 |
晶体学 | 2篇 |
力学 | 15篇 |
数学 | 50篇 |
物理学 | 107篇 |
出版年
2023年 | 3篇 |
2022年 | 9篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 6篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 15篇 |
2015年 | 11篇 |
2014年 | 16篇 |
2013年 | 19篇 |
2012年 | 25篇 |
2011年 | 38篇 |
2010年 | 17篇 |
2009年 | 16篇 |
2008年 | 27篇 |
2007年 | 31篇 |
2006年 | 22篇 |
2005年 | 20篇 |
2004年 | 15篇 |
2003年 | 18篇 |
2002年 | 13篇 |
2001年 | 16篇 |
2000年 | 9篇 |
1999年 | 4篇 |
1998年 | 10篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 13篇 |
1991年 | 4篇 |
1990年 | 11篇 |
1989年 | 7篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1976年 | 2篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1943年 | 2篇 |
排序方式: 共有524条查询结果,搜索用时 15 毫秒
71.
Giordano PC Harteveld CL Heister AJ Batelaan D van Delft P Plug R Losekoot M Bernini LF 《Community genetics》1998,1(4):243-251
The prevalence at birth of hemoglobin defects in the autochthonous North-European population is low. However, the long immigration and colonial history of the Netherlands has resulted in a group of about 1-2 million 'autochthonous' inhabitants, with Asian, South-European or African ancestors, in whom a moderate birth prevalence of globin gene mutations can be expected. Furthermore, at least 10% of the Dutch population consists of recent immigrants from different countries with high birth prevalence of hemoglobinopathies. Because of the endogamous partner choice, which is prevalent in this population, the risk for homozygous progeny remains elevated. At least 100,000 carriers of hemoglobinopathies of recent allochthonous origin are present in the Netherlands, and the number of homozygous children is rising. Prevention by prenatal diagnosis requires a suitable protocol and knowledge about the molecular defects present in the country. Therefore we have analyzed a large number of patients and carriers, both at the hematological and at the DNA level. Our survey revealed 47 different beta-thalassemia determinants, characterized on 223 independent chromosomes from individuals of different ethnic origins. As expected, the most prevalent mutations were largely represented. The cd39 (C-->T) mutation was found in 70% of the immigrants from Morocco, Sardinia and other Central-West-Mediterranean regions while the IVS-I-110 (G-->A) was prevalent in the East-Mediterranean populations. The IVS-I-5 (G-->C) mutation was found in 45% of the patients of Indonesian origin. We also registered 308 independent chromosomes with common structural defects (HbS, HbC, HbE, Hb Lepore, Hb Constant Spring and HbD Punjab) and 33 chromosomes with 19 different, less frequent, rare or very rare mutants. Seven structural mutants were described for the first time and published separately. Furthermore, 139 independent chromosomes with deletional and nondeletional alpha-thalassemia defects were characterized. 相似文献
72.
Stefano Curcio Domenico Gabriele Vincenzo Giordano Vincenza Calabrò Bruno de Cindio Gabriele Iorio 《Rheologica Acta》2001,40(2):154-161
The aim of the present work is to analyze the complex phenomena involved in the concentrated milk clotting process in order
to define general criteria applicable to the design of a continuous coagulator. A full characterization of the rheological
properties of completely hydrolyzed milk as a function of two different parameters, i.e., the coagulator temperature and the
concentration degree of the milk, is presented. The dynamic evolution of loss, G′′, and storage, G′, moduli has been obtained
at different frequency values and for different concentration degrees during the clotting process. Time cure tests have been
performed on completely hydrolyzed milk samples showing that the rate of curing is very high and that the time for rheological
experiments is much too short for testing Winter's theory of gelation. To overcome this problem, the intersect of loss and
storage moduli was used for estimating the coagulation. Coagulation is faster when higher temperatures are used and the consistency
of the final curd is greater if a more concentrated milk is used. A tentative physical explanation based on the network theories
is presented. If an observation time far enough from the crossover point is chosen it can be seen that the curd strength estimated
at 40 °C is about 50 times higher than that one evaluated at 25 °C. Among the considered temperatures, a good processing value
was evaluated at 40 °C.
Received: 6 February 2000 Accepted: 24 October 2000 相似文献
73.
Modeling and Analysis of Seawater Intrusion in the Coastal Aquifer of Eastern Cap-Bon, Tunisia 总被引:5,自引:0,他引:5
Claudio Paniconi Ihsen Khlaifi Giuditta Lecca Andrea Giacomelli Jamila Tarhouni 《Transport in Porous Media》2001,43(1):3-28
A numerical model that treats density-dependent variably saturated flow and miscible salt transport is used to investigate the occurrence of seawater intrusion in the Korba aquifer of the eastern coast of Cap-Bon in northern Tunisia. We examine the interplay between pumping regimes and recharge scenarios and its effect on the saline water distribution. More localized simulations are used to examine, in vertical cross sections, the effects of well location and soil type and the role of the vadose zone in possible remediation actions. The exploratory simulations suggest interesting interactions between the unsaturated zone and the saltwater–freshwater interface with possible implications for groundwater exploitation from shallow unconfined coastal aquifers, involving in one case feedback between seawater intrusion and the high pressure head gradients around the pumping-induced drawdown cone and in another case threshold-like interface displacement for tight soils such as clays. The data processing steps undertaken in this GIS and modeling study are described in some detail, and a critical assessment is given of the data availability and of the requirements for successful monitoring and modeling of seawater intrusion risks in heavily exploited coastal aquifers such as those found in the semi-arid regions of the Mediterranean basin. It is shown how, with the aid of GIS, reasonably reliable information can be assembled from maps, surveys, and other sources of geospatial and hydrogeological data, an approach that is necessary in the many regions of the world with acute water resource problems but with limited means for undertaking systematic data acquisition and environmental monitoring actions. Nonetheless the need for more concerted monitoring of relevant parameters and processes and of closer coordination between monitoring and modeling is stressed. An idea of the extent of over-exploitation of the Korba aquifer is obtained by examining the pumping and rainfall/infiltration data, and the simulation results support groundwater pumping as the mechanism for and seawater intrusion as the origin of the salt contamination observed in the soils and subsurface waters of the Korba plain. 相似文献
74.
75.
76.
Summary A new high-powered ultraviolet laser system is proposed. The system doubles the infrared light from a Nd-Yag laser mode-locked
at 100 MHz, injects this light into a storage-ring cavity to accumulate a high power in the visible and then doubles this
into the ultraviolet at 2600 ?. The power levels anticipated at this wavelength are much larger than those of commercially
available c.w. lasers. The new system can have a far-reaching impact in basic research and, even more so, in a great many
industrial applications. 相似文献
77.
78.
Paolo Giordano Michael Kunzinger Hans Vernaeve 《Journal of Mathematical Analysis and Applications》2015
Based on a refinement of the notion of internal sets in Colombeau's theory, so-called strongly internal sets, we introduce the space of generalized smooth functions, a maximal extension of Colombeau generalized functions. Generalized smooth functions as morphisms between sets of generalized points form a sub-category of the category of topological spaces. In particular, they can be composed unrestrictedly. 相似文献
79.
Truong Nguyen-Ba Huong Nguyen-Thu Thierry Giordano Rémi Vaillancourt 《Applied Numerical Mathematics》2011,61(4):487-500
Strong-stability-preserving (SSP) time-discretization methods have a nonlinear stability property that makes them particularly suitable for the integration of hyperbolic conservation laws. A collection of SSP explicit 3-stage Hermite-Birkhoff methods of orders 3 to 7 with nonnegative coefficients are constructed as k-step analogues of third-order Runge-Kutta methods, incorporating a function evaluation at two off-step points. Generally, these new methods have larger effective CFL coefficients than the hybrid methods of Huang with the same step number k. They have larger maximum scaled step sizes than hybrid methods on Burgers' equations. 相似文献
80.
This article reviews measurements for the canonical flow: incompressible turbulent round jets issuing into a large, ideally
infinite, quiescent domain. The available far-field data on mean velocity, momentum-flux conservation, Reynolds stresses and
triple fluctuation correlations are presented. The budget equations for turbulent kinetic energy and for the individual Reynolds
stresses are shown, including different formulations for dissipation and pressure-velocity correlations. Evidence of the persistence
of source conditions in the self-preserving far field is observed in several cases. This article analyses and compares several
data sets, obtained at different levels of detail, against analytical constraints, discusses limitations and provides insights
aided by reference to recent numerical work. It is hoped that this will prove useful in guiding future experiments and numerical
test cases, where complete details of the jet configuration are required for validation and comparison. 相似文献