全文获取类型
收费全文 | 13078篇 |
免费 | 1429篇 |
国内免费 | 1026篇 |
专业分类
化学 | 9005篇 |
晶体学 | 173篇 |
力学 | 604篇 |
综合类 | 59篇 |
数学 | 1830篇 |
物理学 | 3862篇 |
出版年
2023年 | 177篇 |
2022年 | 239篇 |
2021年 | 379篇 |
2020年 | 479篇 |
2019年 | 486篇 |
2018年 | 412篇 |
2017年 | 370篇 |
2016年 | 568篇 |
2015年 | 552篇 |
2014年 | 637篇 |
2013年 | 1000篇 |
2012年 | 980篇 |
2011年 | 1062篇 |
2010年 | 711篇 |
2009年 | 646篇 |
2008年 | 741篇 |
2007年 | 622篇 |
2006年 | 636篇 |
2005年 | 510篇 |
2004年 | 443篇 |
2003年 | 393篇 |
2002年 | 411篇 |
2001年 | 330篇 |
2000年 | 258篇 |
1999年 | 215篇 |
1998年 | 135篇 |
1997年 | 132篇 |
1996年 | 110篇 |
1995年 | 86篇 |
1994年 | 140篇 |
1993年 | 92篇 |
1992年 | 104篇 |
1991年 | 97篇 |
1990年 | 87篇 |
1989年 | 68篇 |
1988年 | 78篇 |
1987年 | 55篇 |
1986年 | 59篇 |
1985年 | 87篇 |
1984年 | 75篇 |
1983年 | 51篇 |
1982年 | 77篇 |
1981年 | 60篇 |
1980年 | 61篇 |
1979年 | 58篇 |
1978年 | 68篇 |
1977年 | 59篇 |
1976年 | 54篇 |
1975年 | 45篇 |
1973年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
111.
112.
113.
本文拟定的纸色谱法是以苯-乙酸乙酯-甲醇-乙酸(9:2:1:1)作展开剂,将血卟啉衍生物(HPD)分离为五部份,分别测定各部份浸取液的荧光发射光谱,作为一种对血卟啉衍生物组份作对比鉴定的参考方法。采用Ward的高效液相色谱程序对比研究结果表明,国产与美国产HPD的组份近似,均以血卟啉为主要组份,而前者血卟啉的含量较高;二者还均含有羟乙基乙烯基衍生物和羟基乙酸酯,初步研究了血卟啉衍生物在甲醇-水溶剂系统中的高效液相色谱行为,进一步将血卟啉衍生物分离为九部份,有利于单一组份研究。 相似文献
114.
115.
The solid diffusion coefficient of lithium-ion in LiCoO2 cathode material has been investigated by the capacity intermittent titration technique (CITT) at different voltages and at different charge/discharge cycles. By SEM, XRD and FTIR techniques, the structure of LiCoO2 was studied before and after charge-discharge cycles, and the relationship between solid diffusion coefficient and crystal structure was further discussed. CITT results show that the value of Li+ solid diffusion coefficient of LiCoO2 is about 10-12 cm2·s-1. During the whole charge-discharge cycles, the Li+ solid diffusion coefficient decreased within the voltage of 4.0~4.3 V, which is attributed to the change of the structure of LiCoO2. 相似文献
116.
117.
The monodisperse, porous poly(chloromethylstyrene-co-divinylbenzene) beads of 7.9 microm were prepared by a single-step swelling and polymerization method. The seed particles prepared by dispersion polymerization exhibited good absorption of the monomer phase. Based on this media, a weak cation-exchange (WCX) stationary phase for HPLC was synthesized by a new chemically modified method. The prepared resin has advantages of biopolymer separation, high column efficiency, low column backpressure, high protein mass recovery, and good resolution for proteins. The dynamic protein-loading capacity of the synthesized WCX packings was 18.2 mg/g. Five proteins were separated in 3.0 min using the synthesized WCX stationary phase. The experimental results show that the obtained WCX resin has very weak hydrophobicity. The WCX resin was also used for the rapid separation and purification of lysozyme from egg white in 5.0 min with only one step. The purity and specific bioactivity of the purified lysozyme were found to be more than 93% and 70 245 U/mg, respectively. 相似文献
118.
The article herein briefly introduces the story of the birth of click chemistry and its evolution after that. A new angle to interpret click reactions was proposed using the “reactivity‐availability‐functionality” trilogy. CuAAC (Copper‐catalyzed azide‐alkyne cycloaddition), the most popular click reaction by far, was revisited along with the thiol‐ene, metal‐free AAC, SuFEx (Sulfur(VI) fluoride exchange) and the lately discovered diazotransfer process. By encountering more and more near‐perfect reactions, click chemistry is evolving and expanding on the fringe of the chemistry and different scientific disciplines, destination unknown. 相似文献
119.
The thiochlorides Mo6Cl10Y (Y = S, Se, Te) have been prepared; they are isostructural with Nb6I11, space group Pccn, and have four formula units per unit cell. The X-ray structure of Mo6Cl10Se has been determined from three-dimensional single-crystal counter data and refined to a final R value of 0.053 for 3350 independent reflections. The most important result concerning this structure is a statistical distribution of the Se atom on the unit (Mo6X′8) with : so the compound Mo6Cl10Se must be formulated . The diamagnetic and dielectric behavior of these new thiochlorides is discussed. 相似文献
120.