全文获取类型
收费全文 | 2157篇 |
免费 | 172篇 |
国内免费 | 4篇 |
专业分类
2333篇 |
出版年
2024年 | 5篇 |
2023年 | 18篇 |
2022年 | 65篇 |
2021年 | 86篇 |
2020年 | 85篇 |
2019年 | 176篇 |
2018年 | 123篇 |
2017年 | 66篇 |
2016年 | 98篇 |
2015年 | 125篇 |
2014年 | 103篇 |
2013年 | 160篇 |
2012年 | 200篇 |
2011年 | 171篇 |
2010年 | 95篇 |
2009年 | 95篇 |
2008年 | 113篇 |
2007年 | 95篇 |
2006年 | 90篇 |
2005年 | 70篇 |
2004年 | 57篇 |
2003年 | 57篇 |
2002年 | 42篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 8篇 |
1998年 | 9篇 |
1997年 | 11篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 8篇 |
1976年 | 3篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1967年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有2333条查询结果,搜索用时 15 毫秒
51.
R. Rodney Howell Amir I. Arbisser David S. Parsons Charles I. Scott Ursula Fraustadt William R. Collie Robert N. Marshall Oscar Cavazos Ibarra 《American journal of human genetics》1981,33(6):957-967
We have defined a new autosomal recessive disorder in patients stemming from a small community in northern Mexico. Diagnosable at birth, its major symptoms include brittle hair, mental retardation, and nail dysplasia. Structural hair abnormalities are seen by both light and electron microscopy. Hair cystine content is reduced while the copper/zinc ratio in hair is increased. 相似文献
52.
The X-ray crystallographic structure of KvAP, a voltage-gated bacterial K channel, was recently published. However, the position and the molecular movement of the voltage sensor, S4, are still controversial. For example, in the crystallographic structure, S4 is located far away (>30 A) from the pore domain, whereas electrostatic experiments have suggested that S4 is located close (<8 A) to the pore domain in open channels. To test the proposed location and motion of S4 relative to the pore domain, we induced disulphide bonds between pairs of introduced cysteines: one in S4 and one in the pore domain. Several residues in S4 formed a state-dependent disulphide bond with a residue in the pore domain. Our data suggest that S4 is located close to the pore domain in a neighboring subunit. Our data also place constraints on possible models for S4 movement and are not compatible with a recently proposed KvAP model. 相似文献
53.
Inverted Tandem Polymer Solar Cells with Polyethylenimine‐Modified MoOX/Al2O3:ZnO Nanolaminate as the Charge Recombination Layers 下载免费PDF全文
Jae Won Shim Canek Fuentes‐Hernandez Yinhua Zhou Amir Dindar Talha M. Khan Anthony J. Giordano Hyeunseok Cheun Minseong Yun Seth R. Marder Bernard Kippelen 《Liver Transplantation》2014,4(10)
A new charge recombination layer for inverted tandem polymer solar cells is reported. A bilayer of MoOX/Al2O3:ZnO nanolaminate is shown to enable efficient charge recombination in inverted tandem cells. A polymer surface modification on the MoOX/Al2O3:ZnO nanolaminate bilayer increases the work function contrast between the two outward surfaces of the charge recombination layer, further improving the performance of tandem solar cells. An analysis of the electrical, optical, and surface properties of the charge recombination layer is presented. Inverted tandem polymer solar cells, with two photoactive layers comprising poly (3‐hexylthiophene) (P3HT):indene‐C60 bisadduct (IC60BA) for the bottom cell and poly[(4,8‐bis‐(2‐ethylhexyloxy)‐benzo[1,2‐b:4,5‐b']dithiophene)‐2,6‐diyl‐alt‐(4‐(2‐ethylhexanoyl)‐thieno[3,4‐b]thiophene))‐2,6‐diyl] (PBDTTT‐C):[6,6]‐phenyl C61 butyric acid methyl ester (PC60BM) for the top cell, yield an open‐circuit voltage of 1481 mV ± 15 mV, a short‐circuit current density of 7.1 mA cm?2 ± 0.1 mA cm?2, and a fill factor of 0.62 ± 0.01, resulting in a power conversion efficiency of 6.5% ± 0.1% under simulated AM 1.5G, 100 mW cm?2 illumination. 相似文献
54.
55.
56.
Reza Jafarzadeh-Esfehani Seyed Mostafa Parizadeh Amirsaeed Sabeti Aghabozorgi Negar Yavari Ariane Sadr-Nabavi Seyed Alireza Parizadeh Maryam Ghandehari Afsane Javanbakht Afsaneh Rezaei-Kalat Seyed Mahdi Hassanian Mohammad Vojdanparast Gordon A. Ferns Majid Khazaei Amir Avan 《Journal of cellular physiology》2020,235(10):6393-6403
Venous and arterial thrombosis are conditions that have a considerable burden if left untreated. The hypoxia-induced by the occluded vessel can disrupt the circulation of any organ, the cornerstone of treating thrombosis is rapid diagnosis and appropriate treatment. Diagnosis of thrombosis may be made by using laboratory tests or imaging techniques in individuals who have clinical manifestations of a thrombotic event. The use of serum micro ribonucleic acids (RNAs) has recently been applied to the diagnosis of thrombosis. These small RNA molecules are emerging as new diagnostic markers but have had very limited applications in vascular disease. Most of the articles provided various microRNAs with different levels of accuracy. However, there remains a lack of an appropriate panel of the most specific microRNA in the literature. The purpose of the present review was to summarize the existing data on the use of microRNAs as a diagnostic biomarker for venous thrombosis. 相似文献
57.
Amir Sherman Ravit Eshed Rotem Harel-Beja Galil Tzuri Vitaly Portnoy Shahar Cohen Mor Rubinstein Arthur A. Schaffer Joseph Burger Nurit Katzir Ron Ophir 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2013,126(2):349-358
The availability of sequence information for many plants has opened the way to advanced genetic analysis in many non-model plants. Nevertheless, exploration of genetic variation on a large scale and its use as a tool for the identification of traits of interest are still rare. In this study, we combined a bulk segregation approach with our own-designed microarrays to map the pH locus that influences fruit pH in melon. Using these technologies, we identified a set of markers that are genetically linked to the pH trait. Further analysis using a set of melon cultivars demonstrated that some of these markers are tightly linked to the pH trait throughout our germplasm collection. These results validate the utility of combining microarray technology with a bulk segregation approach in mapping traits of interest in non-model plants. 相似文献
58.
Thiosemicarbazones (1-7) and their palladium(II) complexes (1a-7a) of the type [Pd(TSCN)Cl(2)] (where TSCN=thiosemicarbazone) were prepared from 5-nitro thiophene-2-carboxaldehyde and [Pd(DMSO)(2)Cl(2)], respectively. Coordination via the thionic sulphur and the azomethine nitrogen atom of the thiosemicarbazones to the metal ion were confirmed by spectral data. These compounds were screened in vitro against (HK-9) strain of Entamoeba histolytica possess amoebicidal properties. Enhancement of antiamoebic activity resulted due to the introduction of palladium metal in the thiosemicarbazone moiety. The most promising of the group tested are [Pd(5-N-2-TCA-COTSCN)Cl(2)] and [Pd(5-N-2-TCA-AdmTSCN)Cl(2)] comparable to that of metronidazole. 相似文献
59.
David JR Araripe LO Bitner-Mathé BC Capy P Goñi B Klaczko LB Legout H Martins MB Vouidibio J Yassin A Moreteau B 《Genetica》2006,128(1-3):109-122
Zaprionus indianus is a cosmopolitan drosophilid, of Afrotropical origin, which has recently colonized South America. The sexual dimorphism
(SD) of body size is low, males being almost as big as females. We investigated 10 natural populations, 5 from America and
5 from Africa, using the isofemale line technique. Three traits were measured on each fly: wing and thorax length and sternopleural
bristle number. Two indices of SD were compared, and found to be highly correlated (r > 0.99). For the sake of simplicity, only the female/male (F/M) ratio was further considered. A significant genetic variability
of SD was found in all cases, although with a low heritability (intra-class correlation of 0.13), about half the value found
for the traits themselves. For size SD, we did not find any variation among continents or any latitudinal trend, and average
values were 1.02 for wing length and 1.01 for thorax length. Bristle number SD was much greater (1.07). Among mass laboratory
strains, SD was genetically much more variable than in recently collected populations, a likely consequence of laboratory
drift. Altogether, SD, although genetically variable and prone to laboratory drift, is independent of size variations and
presumably submitted to a stabilizing selection in nature. 相似文献
60.
A simple and rapid flow-injection method is described for the determination of iodide, based on potassium permanganate chemiluminescence detection via oxidation of formaldehyde in aqueous hydrochloric acid. The calibration graph was linear over the range 1.0-12 x 10(-6) mol/L (r2 = 0.9955) with relative standard deviations (n = 4) in the range 1.0-3.5%. The detection limit (3sigma) was 1.0 x 10(-7) mol/L, with sample throughput of 120/h. The effect of interfering cations [Ca(II), Mg(II), Ni(II), Fe(II), Fe(III) and Pb(II)] and anions (Cl-, SO4(2-), PO4(3-), NO3-, NO2-, F- and SO3(2-)) were studied. The method was applied to iodized salt samples and the results obtained in the range 0.03 +/- 0.005 - 0.10 +/- 0.006 mg I/g were in reasonable agreement with the amount labelled. The method was statistically compared with the results obtained by titration; no significant disagreement at 95% confidence was observed. 相似文献