全文获取类型
收费全文 | 15640篇 |
免费 | 1180篇 |
国内免费 | 1986篇 |
出版年
2023年 | 221篇 |
2022年 | 301篇 |
2021年 | 363篇 |
2020年 | 465篇 |
2019年 | 618篇 |
2018年 | 500篇 |
2017年 | 427篇 |
2016年 | 474篇 |
2015年 | 445篇 |
2014年 | 810篇 |
2013年 | 1091篇 |
2012年 | 654篇 |
2011年 | 640篇 |
2010年 | 554篇 |
2009年 | 658篇 |
2008年 | 695篇 |
2007年 | 820篇 |
2006年 | 777篇 |
2005年 | 670篇 |
2004年 | 603篇 |
2003年 | 586篇 |
2002年 | 583篇 |
2001年 | 491篇 |
2000年 | 372篇 |
1999年 | 369篇 |
1998年 | 336篇 |
1997年 | 293篇 |
1996年 | 289篇 |
1995年 | 301篇 |
1994年 | 269篇 |
1993年 | 239篇 |
1992年 | 264篇 |
1991年 | 304篇 |
1990年 | 230篇 |
1989年 | 176篇 |
1988年 | 198篇 |
1987年 | 152篇 |
1986年 | 165篇 |
1985年 | 186篇 |
1984年 | 155篇 |
1983年 | 108篇 |
1982年 | 170篇 |
1981年 | 148篇 |
1980年 | 148篇 |
1979年 | 98篇 |
1978年 | 85篇 |
1977年 | 63篇 |
1976年 | 55篇 |
1974年 | 36篇 |
1973年 | 43篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
Elizabeth Holt 《Dialectical Anthropology》2005,29(3-4):387-396
In this paper, I read Leïla Sebbar’s staging in her novel Shérazade: 17 ans, brune, frisée, les yeux verts of the resistance by children of North African and other immigrants in the early 1980s to the French state’s cartographic modes and documents of control. The paper will consider the many uses to which the map was put by the French state in its colonization of North Africa and particularly Algeria, and later in its attempts to control the banlieues its policies of citizenship and cartographic control yielded on the margins of Paris. In this context, I will explore the ways in which the novel’s characters, living clandestinely in a squatt, simultaneously resist, put to use, and even supercede state documents of control as they disrupt everyday life and conduct heists across the city of Paris. The paper will explore unofficial cartographies of Paris, from those afforded by the radios libres and alternative publications such as Libération and Sans Frontièrez, to oral and almost proverbial networks of knowledge criss-crossing the city of Paris, while also tracing the uses to which supplemental cartographic sketches and counterfeit identity cards are put in the pages of the novel. The paper will be in dialogue with theoretical and critical formulations of space, cartography, and state control put forward by Michel de Certeau, Henri Lefebvre, Michel Foucault, and Tom Conley. The paper will conclude with a consideration of the means and limits of resistance by the novel’s characters in the context of this body of theory and criticism. 相似文献
63.
64.
The uptake of two different preparations of99mTechnetium-methylene diphosphonate in fetal rat calvaria is compared. The localization of99mTc after administration of99mTc(Sn)-MDP and99mTc-MDP showed equal distribution in autoradiography. 相似文献
65.
66.
A review of in vitro mutagenesis assessment of metal compounds in mammalian and nonmammalian test systems has been compiled.
Prokaryotic assays are ineffective or inconsistent in their detection of most metals as mutagens, with the notable exception
of hexavalent chromium. Mammalian assay systems appear to be similarly inappropriate for the screening of metal compounds
based upon the limited number of studies that have employed those compounds having known carcinogenic activity. Although of
limited value as screening tests for the detection of potentially carcinogenic metal compounds, the well-characterized in
vitro mutagenesis systems may prove to be of significant value as a means to elucidate mechanisms of metal genotoxicity. 相似文献
67.
The influence of contact guidance on the orientation of colonies of subcultured vascular smooth muscle cells 总被引:1,自引:0,他引:1
Robert C. Buck 《In vitro cellular & developmental biology. Plant》1982,18(9):783-788
Summary Subcultures of smooth muscle cells derived from rat thoracic aorta were grown on plane plastic substrata and on plastic substrata
having ridges molded in them by a heated, ruled template. The cells were found to have a very high degree of contact guidance
when distributed sparsely on the ridged substrata. When the cell density increased multilayered, elongated colonies formed.
On plane substrata these were irregular, curved, and disposed in all directions. On the ridged substrata, however, the colonies
were straight, evenly spaced, and positioned at right angles to the ridges.
Supported by Grant MT1011 from the Medical Research Council of Canada. 相似文献
68.
Quantitative understanding of nanoparticles delivery in a complex vascular networks is very challenging because it involves interplay of transport, hydrodynamic force, and multivalent interactions across different scales. Heterogeneous pulmonary network includes up to 16 generations of vessels in its arterial tree. Modeling the complete pulmonary vascular system in 3D is computationally unrealistic. To save computational cost, a model reconstructed from MRI scanned images is cut into an arbitrary pathway consisting of the upper 4-generations. The remaining generations are represented by an artificially rebuilt pathway. Physiological data such as branch information and connectivity matrix are used for geometry reconstruction. A lumped model is used to model the flow resistance of the branches that are cut off from the truncated pathway. Moreover, since the nanoparticle binding process is stochastic in nature, a binding probability function is used to simplify the carrier attachment and detachment processes. The stitched realistic and artificial geometries coupled with the lumped model at the unresolved outlets are used to resolve the flow field within the truncated arterial tree. Then, the biodistribution of 200 nm, 700 nm and 2 µm particles at different vessel generations is studied. At the end, 0.2–0.5% nanocarrier deposition is predicted during one time passage of drug carriers through pulmonary vascular tree. Our truncated approach enabled us to efficiently model hemodynamics and accordingly particle distribution in a complex 3D vasculature providing a simple, yet efficient predictive tool to study drug delivery at organ level. 相似文献
69.
Andreas Barth 《BBA》2007,1767(9):1073-1101
This review discusses the application of infrared spectroscopy to the study of proteins. The focus is on the mid-infrared spectral region and the study of protein reactions by reaction-induced infrared difference spectroscopy. 相似文献
70.