全文获取类型
收费全文 | 1046篇 |
免费 | 78篇 |
出版年
2023年 | 5篇 |
2022年 | 12篇 |
2021年 | 29篇 |
2020年 | 26篇 |
2019年 | 17篇 |
2018年 | 23篇 |
2017年 | 17篇 |
2016年 | 35篇 |
2015年 | 35篇 |
2014年 | 43篇 |
2013年 | 66篇 |
2012年 | 91篇 |
2011年 | 91篇 |
2010年 | 41篇 |
2009年 | 29篇 |
2008年 | 48篇 |
2007年 | 49篇 |
2006年 | 48篇 |
2005年 | 38篇 |
2004年 | 31篇 |
2003年 | 26篇 |
2002年 | 20篇 |
2001年 | 16篇 |
2000年 | 13篇 |
1999年 | 10篇 |
1998年 | 10篇 |
1997年 | 10篇 |
1996年 | 16篇 |
1995年 | 8篇 |
1994年 | 8篇 |
1993年 | 9篇 |
1992年 | 11篇 |
1991年 | 18篇 |
1990年 | 13篇 |
1989年 | 18篇 |
1988年 | 9篇 |
1987年 | 12篇 |
1986年 | 9篇 |
1985年 | 16篇 |
1984年 | 13篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1979年 | 4篇 |
1978年 | 7篇 |
1976年 | 4篇 |
1974年 | 8篇 |
1972年 | 6篇 |
1969年 | 5篇 |
1968年 | 3篇 |
排序方式: 共有1124条查询结果,搜索用时 31 毫秒
51.
Gupta Praveen Kumar Vaswani Shalini Kumar Vinod Roy Debashis Kumar Muneendra Kushwaha Raju Kumar Avinash Shukla Amit 《Biological trace element research》2020,194(2):379-389
Biological Trace Element Research - This study was conducted to investigate the effect of vanadium (V) supplementation on growth, metabolism, antioxidant, and immunological and endocrine variables... 相似文献
52.
53.
Mamta Sharma Raju Ghosh Suresh Pande 《Archives Of Phytopathology And Plant Protection》2013,46(13-16):797-812
Dry root rot caused by Rhizoctonia bataticola (Macrophomina phaseolina) of chickpea (Cicer arietinum L.) is gaining importance in the changed scenario of climate when growing crop is predisposed to high temperature and moisture stress. Being mainly a soil-inhabiting pathogen, many environmental and soil factors are responsible for the development of disease. No systematic research related to the biology, ecology and epidemiology of dry root rot in chickpea has been conducted so far. Research is needed to improve the identification and characterisation of variability within its epidemiological and pathological niches. Limited literature available on host plant resistance for dry root rot indicated lack of resistant sources for this disease. The present article discusses current status of the disease in the context of climate change and possible management options to alleviate the problem. 相似文献
54.
In continuation of our work on the conformational analysis of succinic acid (SA) and maleic acid (MA) in different solvents, we present here the experimental dielectric and IR and also the ab initio Hartree–Fock calculations of the two dicarboxylic acids in tetrahydrofuran (THF). The dielectric measurements are carried out at microwave X-band frequency of 9.7 GHz and the calculations are performed at STO-3G and 6-31G(d) basis sets. The dielectric data and the dipole moment determined experimentally are compared with the dipole moment determined from the conformal analysis. It is seen that the dielectric properties of SA/MA in THF are much different from that of SA/MA in 1-4, dioxane (1-4D) that we had reported previously. The IR spectra of SA–THF system is also reported here. The present study indicates the possible formation of nano-clusters of SA/MA in THF due to incomplete solvation by THF. 相似文献
55.
Tolperisone and eperisone used as muscle relaxants possess one chiral center each and exist as two optical isomers for each drug. Therefore, enantioselective assays to measure each enantiomer in biological matrices are of great importance. In the present study a simple and complete reverse‐phase liquid chromatography tandem mass spectrometric method for separation and enantioselective determination of tolperisone and eperisone in rat plasma was developed. The analytes were extracted from rat plasma by a simple protein precipitation method with acetonitrile as the extraction solvent. The enantioselective separation of analytes was achieved on a Cellulose Tris (4‐chloro‐3‐methylphenylcarbamate) chiral column with a mobile phase of acetonitrile: 10 mM ammonium acetate in an isocratic mode of elution and mass spectrometric detection. The calibration curve for each enantiomer was found to be linear over 0.2 to 20 ng/mL for each enantiomer. The proposed method exhibited good intra‐ and interday precision (% CV) ranged between 0.95–6.05% and 1.11–8.21%, respectively. The intra‐ and interday accuracy for the proposed assay method ranged between 94.0–100.5% and 92.7–102.1%, respectively. The proposed method was validated as per regulatory guidelines. Chirality 25:622–627, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
56.
The liver is one of the few organs that possess a high capacity to regenerate after liver failure or liver damage. The parenchymal cells of the liver, hepatocytes, contribute to the majority of the regeneration process. Thus, hepatocyte transplantation presents an alternative method to treating liver damage. However, shortage of hepatocytes and difficulties in maintaining primary hepatocytes still remain key obstacles that researchers must overcome before hepatocyte transplantation can be used in clinical practice. The unique properties of pluripotent stem cells (PSCs) and induced pluripotent stem cells (iPSCs) have provided an alternative approach to generating enough functional hepatocytes for cellular therapy. In this review, we will present a brief overview on the current state of hepatocyte differentiation from PSCs and iPSCs. Studies of liver regenerative processes using different cell sources (adult liver stem cells, hepatoblasts, hepatic progenitor cells, etc.) will be described in detail as well as how this knowledge can be applied towards optimizing culture conditions for the maintenance and differentiation of these cells towards hepatocytes. As the outlook of stem cell-derived therapy begins to look more plausible, researchers will need to address the challenges we must overcome in order to translate stem cell research to clinical applications. 相似文献
57.
58.
59.
A distinctive early Miocene-divergent lineage of Old world racer snakes is described as a new genus and species based on three specimens collected from the western Indian state of Gujarat. Wallaceophis gen. et. gujaratenesis sp. nov. is a members of a clade of old world racers. The monotypic genus represents a distinct lineage among old world racers is recovered as a sister taxa to Lytorhynchus based on ~3047bp of combined nuclear (cmos) and mitochondrial molecular data (cytb, ND4, 12s, 16s). The snake is distinct morphologically in having a unique dorsal scale reduction formula not reported from any known colubrid snake genus. Uncorrected pairwise sequence divergence for nuclear gene cmos between Wallaceophis gen. et. gujaratenesis sp. nov. other members of the clade containing old world racers and whip snake is 21–36%. 相似文献
60.
ZnS:Mn nanoparticles were prepared by a chemical precipitation method and characterized by X‐ray diffraction (XRD), field emission gun scanning electron microscope (FEGSEM), and high resolution transmission electron microscopy (HRTEM). Capping agent (mercaptoethanol) concentrations used were 0 M, 0.005 M, 0.01 M, 0.015 M, 0.025 M, 0.040 M, and 0.060 M, and resulted in nanoparticles sizes of 2.98 nm, 2.9 nm, 2.8 nm, 2.7 nm, 2.61 nm, 2.2 nm and 2.1 nm, respectively. The thermoluminescence (TL) glow curve was recorded by heating the sample exposed to UV‐radiation, at a fixed heating rate 1°C sec–1. The TL intensity initially increased with temperature, attained a peak value Im for a particular temperature, and then decreased with further increase in temperature. The peak TL intensity increased with decreasing nanoparticle size, whereas the temperature corresponding to the peak TL intensity decreased slightly with reducing nanocrystal size. As a consequence of increase in surface‐to‐volume ratio and increased carrier recombination rates, the TL intensity increased with decreasing nanoparticle size. It was found that, whereas activation energy slightly decreased with decreasing nanoparticle size, the frequency factor decreased significantly with reduction in nanoparticle size. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献