全文获取类型
收费全文 | 155145篇 |
免费 | 13842篇 |
国内免费 | 8414篇 |
专业分类
化学 | 95919篇 |
晶体学 | 2022篇 |
力学 | 8239篇 |
综合类 | 444篇 |
数学 | 16814篇 |
物理学 | 53963篇 |
出版年
2023年 | 1695篇 |
2022年 | 2732篇 |
2021年 | 3596篇 |
2020年 | 4243篇 |
2019年 | 4142篇 |
2018年 | 4237篇 |
2017年 | 4105篇 |
2016年 | 5865篇 |
2015年 | 4596篇 |
2014年 | 6002篇 |
2013年 | 8836篇 |
2012年 | 9955篇 |
2011年 | 10534篇 |
2010年 | 7548篇 |
2009年 | 7294篇 |
2008年 | 8064篇 |
2007年 | 7447篇 |
2006年 | 6958篇 |
2005年 | 5861篇 |
2004年 | 4964篇 |
2003年 | 4234篇 |
2002年 | 4148篇 |
2001年 | 3904篇 |
2000年 | 3117篇 |
1999年 | 2905篇 |
1998年 | 2511篇 |
1997年 | 2402篇 |
1996年 | 2255篇 |
1995年 | 1924篇 |
1994年 | 1773篇 |
1993年 | 1604篇 |
1992年 | 1566篇 |
1991年 | 1537篇 |
1990年 | 1404篇 |
1989年 | 1304篇 |
1988年 | 1162篇 |
1987年 | 1055篇 |
1986年 | 1001篇 |
1985年 | 1081篇 |
1984年 | 1110篇 |
1983年 | 932篇 |
1982年 | 921篇 |
1981年 | 818篇 |
1979年 | 801篇 |
1978年 | 926篇 |
1977年 | 954篇 |
1976年 | 841篇 |
1975年 | 797篇 |
1974年 | 809篇 |
1973年 | 791篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
Luo Dajuan Liu Bingqian Gao Rong Su Lixia Su Yonghuan 《Journal of Solid State Electrochemistry》2022,26(3):749-759
Journal of Solid State Electrochemistry - Cortisol, a steroid hormone, has been confirmed as a kind of biomarker that reflects the stress response of psychobiology and related adverse health... 相似文献
92.
An oriented tetrahedron defined on four vertices is a set of four cyclic triples with the property that any ordered pair of vertices is contained in exactly one of the cyclic triples. A tetrahedral quadruple system of order with index , denoted by , is a pair , where is an ‐set and is a set of oriented tetrahedra (blocks) such that every cyclic triple on is contained in exactly members of . A is pure if there do not exist two blocks with the same vertex set. When , the spectrum of a pure TQS has been completely determined by Ji. In this paper, we show that there exists a pure if and only if and . A corollary is that a simple also exists if and only if and . 相似文献
93.
94.
E. V. Shadrina O. N. Malinkina T. G. Khonina A. B. Shipovskaya V. I. Fomina E. Yu. Larchenko N. A. Popova I. G. Zyryanova L. P. Larionov 《Russian Chemical Bulletin》2015,64(7):1633-1639
The biomimetic sol—gel synthesis of silicon—chitosan-containing glycerohydrogels was carried out using silicon tetraglycerolate as a precursor. It was found that chitosan accelerates gel formation in weakly acidic media. In more acidic media, the kinetics of the process changes according to the curve with a maximum, which can be attributed to different mechanisms of silanol condensation before and after the isoelectric point. The investigated silicon—chitosan-containing glycerohydrogels exhibit antibacterial, anti-inflammatory, and wound healing activity. The synthesized hybrid glycerohydrogels are promising materials for biomedical applications. 相似文献
95.
96.
Xiaoshuang Luo Xinxian Qin Zhengyi Liu Dan Chen Weiwei Yu Kankan Zhang Deyu Hu 《Biomedical chromatography : BMC》2020,34(1):e4694
A simple and rapid analytical method for the detection of trifloxystrobin, trifloxystrobin acid and tebuconazole in soil, brown rice, paddy plants and rice hulls was established and validated by liquid chromatography with tandem mass spectrometry. Acceptable linearity (R2 > 0.99), accuracy (average recoveries of 74.3–108.5%) and precision (intra- and inter-day relative standard deviations of 0.9–8.8%) were obtained using the developed determination approach. In the field trial, the half-lives of trifloxystrobin and tebuconazole in paddy plants were 5.7–8.3 days in three locations throughout China, and the terminal residue concentrations of trifloxystrobin and tebuconazole were <100 and 500 μg/kg (maximum residue limits set by China), respectively, at harvest, which indicated that, based on the recommended application procedure, trifloxystrobin and tebuconazole are safe for use on rice. The risk assessment results demonstrated that, owing to risk quotient values of both fungicides being <100%, the potential risk of trifloxystrobin and tebuconazole on rice was acceptable for Chinese consumers. These data could provide supporting information for the proper use and safety evaluation of trifloxystrobin and tebuconazole in rice. 相似文献
97.
Valentin A. Semenov Dmitry O. Samultsev Leonid B. Krivdin 《Magnetic resonance in chemistry : MRC》2020,58(6):532-539
The density functional theory calculation of 1H and 13C NMR chemical shifts in a series of ten 10 classically known Strychnos alkaloids with a strychnine skeleton was performed at the PBE0/pcSseg-2//pcseg-2 level. It was found that calculated 1H and 13C NMR chemical shifts provided a markedly good correlation with experiment characterized by a mean absolute error of 0.08 ppm in the range of 7 ppm for protons and 1.67 ppm in the range of 150 ppm for carbons, so that a mean absolute percentage error was as small as ~1% in both cases. 相似文献
98.
Jia Yang Xingang Li Wenjun Li Xin Xi Qian Du Feng Pan Songqing Liu 《Biomedical chromatography : BMC》2020,34(8):e4857
Because of its unpredictable side effects and efficacy, the anticancer drug docetaxel (DTX) requires improved characterisation of its pharmacokinetic profiles through population pharmacokinetic studies. A sensitive and rugged LC–MS/MS method for the detection of DTX in human plasma was developed and optimised using paclitaxel as an internal standard (IS). The plasma samples underwent rapid extraction using hybrid solid-phase extraction-protein precipitation. The analyte and IS were separated with an isocratic system on a Zorbax Eclipse Plus C18 column using water containing 0.05% acetic acid along with 20 μM of sodium acetate and methanol (30/70, v/v) as the mobile phase. Quantification was performed using a triple quadrupole mass spectrometer through multiple reaction monitoring in positive mode, using the m/z 830.3 → 548.8 and m/z 876.3 → 307.7 transitions for DTX and paclitaxel, respectively. The range of the calibration curve was 1–500 ng/mL for DTX, and the linear correlation coefficient was >0.99. The accuracies ranged from −4.6 to 4.2%, and the precision was no higher than 7.0% for the analytes. No significant matrix effect was observed. Both DTX and the IS showed considerable recovery. This method was finally applied to the establishment of a population pharmacokinetic model to optimise the clinical use of DTX. 相似文献
99.
数据包络分析(DEA)是评价供应链系统(Supply chain system)间相对有效性的一种重要的工具,但是传统的DEA不考虑供应链的内部结构,对系统效率评价偏高;而本文所研究两阶段串联供应链系统,考虑把部分中间产品作为最终产品输出,增加额外中间投入的情形.基于所提出的供应链系统结构,本文建立相应的串联结构下的网络DEA模型,并针对所建立模型进行相关理论的研究,给出了串联结构下的生产可能集和规模收益情况判定方法.最后,进行数值实验,以验证我们提出的结论. 相似文献
100.
Dr. Wan‐Ling Liu Ni‐Shin Yang Ya‐Ting Chen Stephen Lirio Cheng‐You Wu Prof. Chia‐Her Lin Prof. Hsi‐Ya Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):115-119
A green and sustainable strategy synthesizes clinical medicine warfarin anticoagulant by using lipase‐supported metal–organic framework (MOF) bioreactors (see scheme). These findings may be beneficial for future studies in the industrial production of chemical, pharmaceutical, and agrochemical precursors. 相似文献