全文获取类型
收费全文 | 1860篇 |
免费 | 140篇 |
国内免费 | 2篇 |
出版年
2022年 | 9篇 |
2021年 | 55篇 |
2020年 | 33篇 |
2019年 | 23篇 |
2018年 | 46篇 |
2017年 | 39篇 |
2016年 | 49篇 |
2015年 | 76篇 |
2014年 | 88篇 |
2013年 | 116篇 |
2012年 | 146篇 |
2011年 | 130篇 |
2010年 | 69篇 |
2009年 | 57篇 |
2008年 | 92篇 |
2007年 | 65篇 |
2006年 | 71篇 |
2005年 | 65篇 |
2004年 | 58篇 |
2003年 | 62篇 |
2002年 | 42篇 |
2001年 | 40篇 |
2000年 | 32篇 |
1999年 | 26篇 |
1998年 | 16篇 |
1997年 | 17篇 |
1995年 | 10篇 |
1994年 | 13篇 |
1992年 | 36篇 |
1991年 | 24篇 |
1990年 | 23篇 |
1989年 | 22篇 |
1988年 | 15篇 |
1987年 | 23篇 |
1986年 | 13篇 |
1985年 | 25篇 |
1984年 | 29篇 |
1983年 | 16篇 |
1982年 | 16篇 |
1981年 | 18篇 |
1979年 | 24篇 |
1978年 | 14篇 |
1977年 | 13篇 |
1975年 | 12篇 |
1974年 | 14篇 |
1973年 | 10篇 |
1969年 | 13篇 |
1968年 | 10篇 |
1967年 | 9篇 |
1966年 | 10篇 |
排序方式: 共有2002条查询结果,搜索用时 31 毫秒
101.
The use of ultra performance liquid chromatography coupled to data independent tandem mass spectrometry with traveling wave ion mobility for detection and structural identification of ether‐linked glycerophosphoethanolamine is described. The experimental design generates 4D data (chromatographic retention time, precursor accurate mass, drift time with associated calculated collisional cross‐section, and time‐aligned accurate mass diagnostic product ions) for each ionization mode. Confident structure identification depends on satisfying 4D data confirmation in both positive and negative ion mode. Using this methodology, a number of ether‐linked glycerophosphoethanolamine lipids are structurally elucidated from mouse brain lysosomes. It is further determined that several ether‐linked glycerophosphoethanolamine structures are differentially abundant between lysosomes isolated from mouse cortex following traumatic brain injury as compared to that of sham animals. The combined effort of aligning multi‐dimensional mass spectrometry data with a well‐defined traumatic brain injury model lays the foundation for gaining mechanistic insight in the role lysosomal membrane damage plays in neuronal cell death following brain injury. 相似文献
102.
103.
104.
105.
A central theoretical goal of epidemiology is the construction of spatial models of disease prevalence and risk, including maps for the potential spread of infectious disease. We provide three continent-wide maps representing the relative risk of malaria in Africa based on ecological niche models of vector species and risk analysis at a spatial resolution of 1 arc-minute (9 185 275 cells of approximately 4 sq km). Using a maximum entropy method we construct niche models for 10 malaria vector species based on species occurrence records since 1980, 19 climatic variables, altitude, and land cover data (in 14 classes). For seven vectors (Anopheles coustani, A. funestus, A. melas, A. merus, A. moucheti, A. nili, and A. paludis) these are the first published niche models. We predict that Central Africa has poor habitat for both A. arabiensis and A. gambiae, and that A. quadriannulatus and A. arabiensis have restricted habitats in Southern Africa as claimed by field experts in criticism of previous models. The results of the niche models are incorporated into three relative risk models which assume different ecological interactions between vector species. The "additive" model assumes no interaction; the "minimax" model assumes maximum relative risk due to any vector in a cell; and the "competitive exclusion" model assumes the relative risk that arises from the most suitable vector for a cell. All models include variable anthrophilicity of vectors and spatial variation in human population density. Relative risk maps are produced from these models. All models predict that human population density is the critical factor determining malaria risk. Our method of constructing relative risk maps is equally general. We discuss the limits of the relative risk maps reported here, and the additional data that are required for their improvement. The protocol developed here can be used for any other vector-borne disease. 相似文献
106.
107.
Sohini Guha Firoz Molla Monolina Sarkar Fernando Ibañez Adriana Fabra Maitrayee DasGupta 《Environmental microbiology》2022,24(6):2732-2746
Dalbergoids are typified by crack-entry symbiosis which is evidenced to be Nod Factor (NF)-independent in several Aeschynomene legumes. Natural symbionts of the dalbergoid legume Arachis hypogaea are always NF-producing, prompting us to check whether symbiosis in this legume could also be NF-independent. For this, we followed the symbiosis with two NF-containing bradyrhizobial strains – SEMIA6144, a natural symbiont of Arachis and ORS285, a versatile nodulator of Aeschynomene legumes, along with their corresponding nodulation (nod) mutants. Additionally, we investigated NF-deficient bradyrhizobia like BTAi1, a natural symbiont of Aeschynomene indica and the WBOS strains that were natural endophytes of Oryza sativa, collected from an Arachis-Oryza intercropped field. While SEMIA6144ΔnodC was non-nodulating, both ORS285 and ORS285ΔnodB could induce functional nodulation, although with lower efficiency than SEMIA6144. On the other hand, all the NF-deficient strains – BTAi1, WBOS2 and WBOS4 showed comparable nodulation with ORS285 indicating Arachis to harbour an NF-independent mechanism of symbiosis. Intriguingly, symbiosis in Arachis, irrespective of whether it was NF-dependent or independent, was always associated with the curling or branching of the rosette root hairs at the lateral root bases. Thus, despite being predominantly described as an NF-dependent legume, Arachis does retain a vestigial, less-efficient form of NF-independent symbiosis. 相似文献
108.
Babichuk Nicole Sarkar Atanu Mulay Shree Knight John Bautista Joseph James Young Cora J. 《EcoHealth》2022,19(1):99-113
EcoHealth - Presence of PBDEs tested in 127 liver samples from Atlantic Cod (Gadus morhua) and Turbot (Scophthalmus Maximus) and 80 adult participants from two rural Newfoundland communities.... 相似文献
109.
Pankaj A. Gorule Manoj Pise Sanjay Kharat Sandip D. Tapkir Pradnya Londhe Soma Sarkar Sachin M. Gosavi 《Zeitschrift fur angewandte Ichthyologie》2019,35(4):1044-1046
Length–weight relationships (LWRs) were estimated for nine freshwater fish species collected three times using a scoop net (mesh size 0.3–0.5 cm), cast net (mesh size 1–1.5 cm) and gillnet (mesh size 2.5–4.5 cm) from six rivers of the Western Ghats of India during August 2017–October 2018. The b values for LWRs varied from 2.862 to 3.656 (R2 > 0.916 and p < 0.0001 for all species). 相似文献
110.
Kirk C. McGilvray Rajabrata Sarkar Khanh Nguyen Christian M. Puttlitz 《Journal of biomechanics》2010,43(15):2941-2947
Although biomechanical studies of the normal rat vein wall have been reported (Weizsacker, 1988, Plante, 2002), there are no published studies that have investigated the mechanical effects of thrombus formation on murine venous tissue. In response to the lack of knowledge concerning the mechanical consequences of thrombus resolution, distinct thrombus-induced changes in the biomechanical properties of the murine vena cava were measured via biaxial stretch experiments. These data served as input for strain energy function (SEF) fitting and modeling (Gasser et al., 2006). Statistical differences were observed between healthy and diseased tissue with respect to the structural coefficient that represents the response of the non-collagenous, isotropic ground substance. Alterations following thrombus formation were also noted for the SEF coefficient which describes the anisotropic contribution of the fibers. The data indicate ligation of the vena cava leads to structural alterations in the ground substance and collagen fiber network. 相似文献