全文获取类型
收费全文 | 3538篇 |
免费 | 104篇 |
国内免费 | 3篇 |
专业分类
化学 | 1904篇 |
晶体学 | 76篇 |
力学 | 112篇 |
数学 | 858篇 |
物理学 | 695篇 |
出版年
2023年 | 24篇 |
2022年 | 43篇 |
2021年 | 69篇 |
2020年 | 113篇 |
2019年 | 106篇 |
2018年 | 188篇 |
2017年 | 162篇 |
2016年 | 211篇 |
2015年 | 134篇 |
2014年 | 198篇 |
2013年 | 463篇 |
2012年 | 227篇 |
2011年 | 239篇 |
2010年 | 214篇 |
2009年 | 161篇 |
2008年 | 219篇 |
2007年 | 196篇 |
2006年 | 102篇 |
2005年 | 60篇 |
2004年 | 52篇 |
2003年 | 53篇 |
2002年 | 49篇 |
2001年 | 46篇 |
2000年 | 30篇 |
1999年 | 20篇 |
1998年 | 28篇 |
1997年 | 24篇 |
1996年 | 15篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1991年 | 6篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1986年 | 6篇 |
1985年 | 14篇 |
1984年 | 20篇 |
1983年 | 9篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1978年 | 8篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1970年 | 4篇 |
1969年 | 5篇 |
1968年 | 4篇 |
1967年 | 5篇 |
排序方式: 共有3645条查询结果,搜索用时 0 毫秒
121.
Filiz Kuralay Arzum Erdem Serdar Abacı Haluk Özyörük Attila Yıldız 《Electrochemistry communications》2009,11(6):1242-1246
Poly(vinylferrocenium) (PVF+) modified electrode was developed in this study for the electrochemical sensing of DNA based on the oxidation signals of polymer, adenine and guanine. Experimental parameters, such as; polymeric film thickness, DNA immobilization time and DNA concentration were examined in order to obtain more sensitive and selective electrochemical signals. After optimization studies, DNA hybridization was investigated. 相似文献
122.
Seda Ünlü Göknur Yaşa Atmaca Fikriye Tuncel Elmalı Ali Erdoğmuş 《Photochemistry and photobiology》2023,99(5):1233-1239
Although the sonophotodynamic method has an effective therapeutic outcome for anticancer treatment compared with the photodynamic method, there are not enough related studies in the literature and this study aims to contribute to the development of sonophotodynamic studies. For this purpose, the Schiff base substituted silicon phthalocyanines were designed and synthesized as effective sensitizer candidates and the photophysicochemical and sonophotochemical features of the phthalocyanines were examined to increase singlet oxygen efficiency. The calculated ΦΔ values indicate that the contribution of substituent groups improved the production of singlet oxygen compared with silicon (IV) phthalocyanine dichloride (SiPcCI2) and also the sonophotochemical applications increased the singlet oxygen yields. The ΦΔ values (ΦΔ = 0.76 for axially bis-{4-[(E)-(pyridin-3-ylimino)methyl]phenol} substituted silicon (IV) phthalocyanine ( 2a ), 0.68 for axially bis-4-[(E)-{[(pyridin-3-yl)methyl]imino}methyl]phenol substituted silicon (IV) phthalocyanine ( 2b ) in photochemical study) reached to ΦΔ = 0.98 for 2a , 0.94 for 2b in sonophotochemical study. This article will enrich the literature on increasing singlet oxygen yield. 相似文献
123.
124.
U. Ceren Başköse Sevgi Haman Bayarı Semran Sağlam Hacı Özışık 《Central European Journal of Chemistry》2012,10(2):395-406
The conformational analysis of rasagiline [N-propargyl-1(R)-aminoindan] was performed by the density functional theory (DFT) B3LYP method using the 6–31++G (d,p) basis set. A single
point energy calculations based on the B3LYP optimized geometries were also performed at MP2/6-31++G (d, p) level. The vibrational
frequencies of the most stable conformer of rasagiline was calculated at the B3LYP level and vibrational assignments were
made for normal modes on the basis of scaled quantum mechanical force field (SQM) method. The influence of mesylate and ethanedisulfonate
salts on the geometry of rasagiline free base and its normal modes are also discussed.
相似文献
125.
U. Avcıbaşı H. Demiroğlu P. Ünak F. Z. B. Müftüler Ç. A. İçhedef F. G. Gümüşer 《Journal of Radioanalytical and Nuclear Chemistry》2010,285(2):207-214
Bleomycins (BLMs; BLM, A2, and B2) were labeled with 131I and radiopharmaceutical potentials were investigated using animal models in this study. Quality control procedures were
carried out using thin layer radiochromatography (TLRC), high performance liquid chromatography (HPLC), and liquid chromatography
(LC/MS/MS). Labeling yields of radiolabeled BLMs were found to be 90, 68, and 71%, respectively. HPLC chromatograms were taken
for BLM and cold iodinated BLM (127I-BLM). Five peaks were detected for BLM and three peaks for 127I-BLM in the HPLC studies. Two peaks belong to isomers of BLM. The isomers of BLM were purified with using HPLC. Biological
activity of BLM was determined on male Albino Wistar rats by biodistribution and scintigraphic studies were performed for
BLMs by using New Zelland rabbits. The biodistribution results of 131I-BLM showed high uptake in the stomach, the bladder, the prostate, the testicle, and the spinal cord in rats. Scintigraphic
results on rabbits agrees with that of biodistributional studies on rats. The scintigraphy of radiolabeled isomers (131I-A2 and 131I-B2) are similiarly found with that of 131I-BLM. 相似文献
126.
Volkan Çakır Dilek Çakır Zekeriya Bıyıklıoğlu Halit Kantekin 《Journal of inclusion phenomena and macrocyclic chemistry》2014,78(1-4):61-70
In this study, a new phthalonitrile derivative 3 bearing 1,3-bis[3(dimethylamino)phenoxy]propan-2-ol 1, metal-free phthalocyanine (Pc) 4, metallophthalocyanines (MPcs) 5–7 and their quaternized derivatives 4a–7a were synthesized. Metal-free Pc 4 was prepared by cyclotetramerization of phthalonitrile derivate 3 and MPcs 5–7 were synthesized by heating 3 with NiCl2, CoCl2 and CuCl2 in n-pentanol in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene, respectively. Quaternization of the dimethylamino functionality produced quaternized octacationic water soluble metal-free, Ni, Co and Cu Pcs which were soluble in water, DMF, DMSO. The aggregation behaviour of these compounds were investigated in different concentrations of chloroform for metal-free, Ni, Co and Cu Pcs. The effect of solvents on absorption spectra were studied in various organic solvents. The novel compounds were characterized using IR, 1H-, 13C NMR, UV–vis and MS spectral data. 相似文献
127.
Aydın Aktaş Ünzile Keleştemur Yetkin Gök Sevgi Balcıoğlu Burhan Ateş Muhittin Aygün 《Journal of the Iranian Chemical Society》2018,15(1):131-139
In this study, a series of unsymmetrically 2-morpholinoethyl-substituted benzimidazolium salts and their Ag(I)NHC complexes were synthesized. The 1,3-dialkylbenzimidazolium salts (1a–d) were synthesized in dimethylformamide at 80 °C temperature from the N-(2-morpholinoethyl)benzimidazole and alkyl halides. The Ag(I)NHC complexes (2a–d) were synthesized in dichloromethane at room temperature from the benzimidazolium salts and Ag2O. All compounds were characterized by spectroscopic techniques (NMR and FT-IR) and elemental analyses. Also, the salt 1c and complex 2c were characterized by single-crystal X-ray crystallography. Anticancer activities of 2-morpholinoethyl-substituted benzimidazolium salts and Ag(I)NHC complexes were investigated against the MCF-7 breast cancer cell line, and the IC30 and IC50 values of these compounds were found to be in the range of 241–490 and 6–14 µM, respectively. 相似文献
128.
Random copolymers of N-isopropylacrylamide (NIPA) and 4-vinylphenylboronic acid (VPBA) were obtained by solution polymerization using 2,2′-azobisizobutyronitrile as the initiator in ethanol at 65 °C. NIPA-co-VPBA copolymer exhibited both temperature- and pH-sensitivity. Thermally reversible phase transitions were observed both in the acidic and alkaline pH region for the copolymers produced with different VPBA/NIPA feed ratios. The pH dependency of the lower critical solution temperature (LCST) was stronger for the copolymers produced with higher VPBA feed concentrations. RNA was selected as a model biomolecule having vicinal-diol and amino groups that were potentially reactive with the boronic acid groups of NIPA-co-VPBA copolymer. The effect of RNA concentration on the LCST of NIPA-co-VPBA copolymer was investigated in aqueous media at different pHs. Although no significant effect was observed at pH 4, 7 or 10.5, the LCST decreased linearly with increasing RNA concentration at a pH approximately equal to the pKa of boronic acid. This behavior was explained by considering the binding of RNA onto the copolymer chains to occur via two types of complex formation. For the formation of these complexes, the amino and vicinal-diol groups of RNA should react with the boronic acid groups of the copolymer in the tetrahedral anionic form. The results indicated that NIPA-co-VPBA copolymer could be utilized as a new reagent for the determination of RNA concentration in aqueous media. The proposed method was valid for the RNA concentration range of 0–4 g · mL−1.
129.
Esra Korkmaz Kirakli Gökhan Takan Sinan Hoca F. Zümrüt Biber Müftüler Ayfer Yurt Kılçar Serra Arun Kamer 《Journal of Radioanalytical and Nuclear Chemistry》2018,315(3):595-602
The purpose of this study was to assess SPION’s in vitro radiosensitizer effect at 6MV-energies and to calculate nanoparticle enhancement ratio (NER) of SPIONs. Citrate coated-SPION’s were synthesized. Trypan-blue, metabolic activity tests were performed. Cell cultures were irradiated at 0,2,4,6,8 Gy at 6MV-energy. Clonogenic survival assays, NER calculations were carried out. SPIONs were biocompatible. NERs were cell-line specific and dose dependent. The highest radiosensitization were seen in radiosensitive MCF-7 and MDAH-2447 cells at 2 Gy (NER:1.49 and 1.39 respectively), in relatively radioresistant MDA-MB-231 cells at 4 Gy (NER:1.20). By increasing doses radiosensitizer effect disappeared. There is possibility that by synergistic effect, SPIONs may cause dose-dependent and cell-line specific radiosensitization at 6MV. 相似文献
130.
Savas Lemiye Atabek Arslan Cagrialp Hacioglu Fırat Dogan Mehmet 《Journal of Thermal Analysis and Calorimetry》2018,134(3):1657-1666
Journal of Thermal Analysis and Calorimetry - In the current study, huntite and hydromagnesite (HH) was used as flame-retardant additive in linear low-density polyethylene (LLDPE). The effect of HH... 相似文献