全文获取类型
收费全文 | 8744篇 |
免费 | 491篇 |
国内免费 | 6篇 |
出版年
2023年 | 72篇 |
2022年 | 67篇 |
2021年 | 253篇 |
2020年 | 151篇 |
2019年 | 173篇 |
2018年 | 236篇 |
2017年 | 220篇 |
2016年 | 278篇 |
2015年 | 361篇 |
2014年 | 414篇 |
2013年 | 574篇 |
2012年 | 594篇 |
2011年 | 563篇 |
2010年 | 344篇 |
2009年 | 282篇 |
2008年 | 394篇 |
2007年 | 359篇 |
2006年 | 342篇 |
2005年 | 339篇 |
2004年 | 281篇 |
2003年 | 228篇 |
2002年 | 238篇 |
2001年 | 208篇 |
2000年 | 179篇 |
1999年 | 164篇 |
1998年 | 61篇 |
1997年 | 56篇 |
1996年 | 67篇 |
1995年 | 52篇 |
1994年 | 59篇 |
1993年 | 41篇 |
1992年 | 120篇 |
1991年 | 117篇 |
1990年 | 89篇 |
1989年 | 96篇 |
1988年 | 89篇 |
1987年 | 90篇 |
1986年 | 86篇 |
1985年 | 93篇 |
1984年 | 80篇 |
1983年 | 50篇 |
1982年 | 50篇 |
1981年 | 43篇 |
1980年 | 48篇 |
1979年 | 78篇 |
1978年 | 58篇 |
1977年 | 49篇 |
1976年 | 43篇 |
1974年 | 39篇 |
1973年 | 44篇 |
排序方式: 共有9241条查询结果,搜索用时 15 毫秒
91.
The movement of radioactively labelled polypeptides into the microtubule-associated transport channels in the ovaries of a hemipteran insect has been analysed using SDS-polyacrylamide slab gel electrophoresis and fluorography. The patterns of label suggest that the microtubules which pack the transport channels form a relatively static cytoskeleton while other components move independently from them along the channels. As well as illustrating the functional organisation of microtubule-associated transport in this system our studies of labelled proteins have also provided clues as to the mechanism of transport itself. 相似文献
92.
93.
94.
The geminate recombination of CO with Hb following dissociation by a 10-ns laser pulse has been studied as a function of pH (9.2 and 7.0 without inositol hexaphosphate and 6.0 with inositol hexaphosphate) and temperature (5-35 degrees C). The hemoglobins studied included adult, Rothschild, rabbit, opossum, and carp. Despite significant differences in their structural and functional properties, the first four of these hemoglobins show similar trends in the yields, rates, and activation energies of the geminate recombination. The nature of the "cage recombination" in hemoglobin is discussed in the light of such findings. Neither a slow diffusion model nor a model based upon a specific non-heme binding site accounts for the observations. 相似文献
95.
Perfusion of Langendorff rat hearts with [14C]adenosine yields an acid-insoluble, radioactive product whose concentration falls during ischaemia. The properties of the substance show that it is a polyribonucleotide. It is suggested that it may be mitochondrial poly A acting as a storage form of adenine nucleotides. 相似文献
96.
97.
Two buffaloes with full-term pregnancy suffered from dystocia because the cervix did not dilate in spite of strong labour pains and other parturition signs shown by each animal. The urinary bladder, cervix, vagina and surrounding area were very firm. Dead, emphysemated fetuses were removed by caesarean in each case and anuria was also noticed. One buffalo died and the other was euthanised after surgery because it did not improve. The post-mortem examinations revealed transitional cell carcinoma of urinary bladder infiltrating the cervix, vagina and surrounding area in each case. 相似文献
98.
99.
A note on some Eurotatoria from Panjab State,India 总被引:1,自引:1,他引:0
Among 35 eurotatorian species presently reported from Panjab State, India, ten species are new records to this region while eight are new records from N. W. India. A new synonym is proposed and biogeographical remarks are made. 相似文献
100.
5-Acetamido-4,7,8,9-tetra-O-acetyl-2,3,5-trideoxy-2-fluoro-D-glycero-alp ha- and -beta-D- galacto -2- nonulosonic acid methyl esters and the beta-chloro analog were synthesized from N-acetylneuraminic acid. Their 1H- and 13C-n.m.r.spectra were completely assigned by using single-frequency decoupling, off-resonance decoupling, and spin-simulation programs. Bond angles estimated from the 1H coupling-constants indicate that all of the compounds adopt the 2C5 (L) conformation with minor conformational differences in the C3 side chain. 5-Acetamido-2,3,5,-tri-deoxy-2-fluoro-D-glycero-alpha- and -beta-D- galacto -2- nonulosonic acid and their methyl esters were also prepared. 相似文献