全文获取类型
收费全文 | 3260篇 |
免费 | 939篇 |
国内免费 | 480篇 |
专业分类
化学 | 2606篇 |
晶体学 | 8篇 |
力学 | 200篇 |
综合类 | 26篇 |
数学 | 229篇 |
物理学 | 1610篇 |
出版年
2023年 | 26篇 |
2022年 | 74篇 |
2021年 | 77篇 |
2020年 | 98篇 |
2019年 | 124篇 |
2018年 | 109篇 |
2017年 | 148篇 |
2016年 | 147篇 |
2015年 | 281篇 |
2014年 | 269篇 |
2013年 | 404篇 |
2012年 | 329篇 |
2011年 | 321篇 |
2010年 | 266篇 |
2009年 | 280篇 |
2008年 | 276篇 |
2007年 | 196篇 |
2006年 | 190篇 |
2005年 | 157篇 |
2004年 | 142篇 |
2003年 | 142篇 |
2002年 | 95篇 |
2001年 | 85篇 |
2000年 | 75篇 |
1999年 | 57篇 |
1998年 | 67篇 |
1997年 | 46篇 |
1996年 | 41篇 |
1995年 | 35篇 |
1994年 | 32篇 |
1993年 | 24篇 |
1992年 | 12篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有4679条查询结果,搜索用时 15 毫秒
91.
92.
93.
Subhendu Bhowmik Garima Pandey Dr. Sanjay Batra 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(32):10487-10491
94.
A protocol for the direct cross coupling of trialkylsilyl‐alkynes bearing electron‐withdrawing groups and aryl halides using a Pd/Ag catalytic system is described. The procedure allows the straightforward synthesis of a variety of alkynylphosphonates and aryl propiolates derivatives in good yields. 相似文献
95.
96.
97.
98.
99.
Venkata Rami Reddy Vaka Jaswanth Kumar Inamadugu Nageswara Rao Pilli Mullangi Ramesh Hussain Reddy Katreddi 《Biomedical chromatography : BMC》2013,27(11):1406-1412
An improved, simple and highly sensitive LC‐MS/MS method has been developed and validated for quantification of febuxostat with 100 μL human plasma using febuxostat‐d7 as an internal standard (IS) according to regulatory guidelines. The analyte and IS were extracted from human plasma via liquid–liquid extraction using diethyl ether. The chromatographic separation was achieved on a Zorbax C18 column using a mixture of acetonitrile and 5 mm ammonium formate (60:40, v/v) as the mobile phase at a flow rate of 0.5 mL/min. The total run time was 5.0 min and the elution of febuxostat and IS occurred at 1.0 and 1.5 min, respectively. A linear response function was established for the range of concentrations 1–6000 ng/mL (r > 0.99). The precursor to product ion transitions monitored for febuxostat and IS were m/z 317.1 → 261.1 and 324.2 → 262.1, respectively. The intra‐ and inter‐day precisions (%RSD) were within 1.29–9.19 and 2.85–7.69%, respectively. The proposed method was successfully applied to pharmacokinetic studies in humans. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
100.
Y chromosome kits are successfully applied in cases where human biological material exists. With the development of genotyping ability, more Y chromosomal markers are needed for finer identification of male individuals and lineages. In this study, a developmental validation of a newly emerged Y chromosome kit that combines two different kinds of markers: 38 Y-STRs and 3 Y-indels are conducted. The results show that this kit has high sensitivity when there is a small amount of DNA (125 pg), more than one male (minor:major = 1:7), or a mixture of males and females (male:female = 125pg:1875pg), inhibited substances (800 μM hematin and more than 1600 ng/μL humic acid). The kit exhibits high precision level with a standard deviation of allele size no more than 0.14 nt. Locus DYS481 shows the largest stutter rate, with three stutters per true allele. Population samples are well identified (MP of 0.001106), and mutations can be observed in father–son pairs (46 mutations in 70 pairs, 10 in locus DYS627). Out of all the population samples, 13.2% belong to haplogroup M117-O2a2b1a1, with their ethnic group being Han Chinese. The results show that this kit can improve the performance of identifying male individuals, obtaining more unique haplotypes (increasing from 894 to 918 of 1000 male samples) and higher discrimination capacity (increasing from 0.942 to 0.955) in this study compared to previous widely used Yfiler Plus kit. Besides, it gives information about their paternal lineages in forensic genetic casework and genealogical database construction. 相似文献