全文获取类型
收费全文 | 3598篇 |
免费 | 197篇 |
国内免费 | 1篇 |
出版年
2022年 | 15篇 |
2021年 | 39篇 |
2020年 | 32篇 |
2019年 | 49篇 |
2018年 | 57篇 |
2017年 | 38篇 |
2016年 | 76篇 |
2015年 | 115篇 |
2014年 | 141篇 |
2013年 | 258篇 |
2012年 | 221篇 |
2011年 | 216篇 |
2010年 | 126篇 |
2009年 | 119篇 |
2008年 | 212篇 |
2007年 | 200篇 |
2006年 | 177篇 |
2005年 | 177篇 |
2004年 | 168篇 |
2003年 | 192篇 |
2002年 | 172篇 |
2001年 | 87篇 |
2000年 | 99篇 |
1999年 | 82篇 |
1998年 | 53篇 |
1997年 | 44篇 |
1996年 | 40篇 |
1995年 | 29篇 |
1994年 | 29篇 |
1993年 | 21篇 |
1992年 | 38篇 |
1991年 | 39篇 |
1990年 | 34篇 |
1989年 | 33篇 |
1988年 | 19篇 |
1987年 | 21篇 |
1986年 | 28篇 |
1985年 | 32篇 |
1984年 | 23篇 |
1983年 | 25篇 |
1982年 | 18篇 |
1981年 | 26篇 |
1980年 | 13篇 |
1978年 | 17篇 |
1977年 | 18篇 |
1975年 | 22篇 |
1974年 | 13篇 |
1973年 | 16篇 |
1972年 | 12篇 |
1966年 | 9篇 |
排序方式: 共有3796条查询结果,搜索用时 31 毫秒
91.
Mitsuhiko Akaboshi Masato Noda Kenichi Kawai Hirotoshi Maki Keizo Kawamoto 《Origins of life and evolution of the biosphere》1979,9(3):181-186
Radical formation in9 0Y--irradiated D- and L-alanines was studied using ESR. It was observed that the relative radical concentration by -irradiation was distinguishably (13.9–21.5%) more in D-alanine than in L-alanine. Discussion was made on the possible mechanisms for the observed results. 相似文献
92.
93.
A male infant with monosomy 21. 总被引:2,自引:0,他引:2
A male infant with total monosomy 21 identified by Q-, G- and R-banding is described. His main symptoms are hypertonia, micrognathia, microphthalmus, imperforate anus, ambiguous external genitalia, floating and malopposed thumbs, overlying fingers, right clubfoot and growth retardation. Both parents are phenotypically as well as karotypically normal. 相似文献
94.
Vibrio parahaemolyticus was observed to adsorb onto chitin particles and copepods. The efficiency of adsorption was found to be dependent on pH and on the concentration of NaC1 and other ions found in seawater. Highest efficiency was observed in water samples collected from Chesapeake Bay and lowest in water from the open sea. V. parahaemolyticus was found to adborb onto chitin with the highest efficiency of the several bacterial strains tested. Escherichia coli and Pseudomonas fluorescens did not adsorb onto chitin. The adsorption effect is considered to be one of the major factors determining the distribution of this species and affecting the annual cycle of V. parahaemolyticus in the estuarine system. 相似文献
95.
Y Kaneko 《Hormones et métabolisme》1976,8(3):202-206
Thyroid cells from euthyroid patients with Graves' disease were cultured in a chemically defined medium. The cells preserved the ability to respond to TSH with 8-fold increase in cyclic AMP concentration. This cyclic AMP response to TSH was diminished by prior exposure of cells to TSH. The decrease in cyclic AMP response to TSH induced to TSH was reversible, was not associated with a similar decrease to cyclic AMP response to PGE1, and could not be attributed to increased phosphodiesterase activity or to decreased adenyl cyclase activity. The partial resistence to TSH stimulation of thyroid cells previously exposed to TSH may be due to changes in the TSH receptor, possibly caused by TSH itself. 相似文献
96.
Kenichi Takaya 《The Histochemical journal》1976,8(1):13-23
Synopsis When cryostat sections of endocrine tissue were examined in a dark-field microscope, a brilliant granular luminescence was revealed in the endocrine cells thought to be concerned with protein or polypeptide hormone production. The sections were prepared from fresh materials either frozen in a cryostat chamber at –25°C, in dry ice-acetone, or fixed in formalin-calcium for 24 hr. The neurosecretory substance in the hypothalamus and the posterior lobe of the pituitary showed a blue luminescence; the acidophil cells of the anterior lobe of the pituitary, orange; basophil cells, green or blue; intermediate lobe cells, no luminescence; thyroid C cells, white-blue; pancreatic A cells, blue; B cells, orange; adrenomedullary cells, greenish blue; enterochromatin cells, green; and other endocrine cells in the gastrointestinal tract, blue or orange. After tearing and spreading the pituitary and hypothalamus with a pair of needles on a glass slide, and examining the teased specimen by dark-field microscopy, various cells of different luminescent colours became apparent in the anterior lobe of the pituitary, a blue fluorescent substance in the posterior lobe, and neurosecretory cell bodies in the hypothalamus. The different colours appear to be inherent in the granules of living tissues. 相似文献
97.
98.
99.
Sumiko Hara Chisato Kaneko Hiroatsu Matsumoto Takeshi Nishino Tadao Takeuchi Takeo Mori 《Nucleosides, nucleotides & nucleic acids》2013,32(2-4):571-582
Abstract Novel β-D-ribofuranosides having a 5-substituted imidazo [4,5-d] [1,3]thiazine ring, including the S6-congener 3 of oxanosine 2, were synthesized for screening their anticancer and antiviral activities. 相似文献
100.
Yuko?T. Sato Shun Watanabe Takahiro Kenmotsu Masatoshi Ichikawa Yuko Yoshikawa Jun Teramoto Tadayuki Imanaka Akira Ishihama Kenichi Yoshikawa 《Biophysical journal》2013,105(4):1037-1044
The effects of nucleoid proteins Fis and Dps of Escherichia coli on the higher order structure of a giant DNA were studied, in which Fis and Dps are known to be expressed mainly in the exponential growth phase and stationary phase, respectively. Fis causes loose shrinking of the higher order structure of a genome-sized DNA, T4 DNA (166 kbp), in a cooperative manner, that is, the DNA conformational transition proceeds through the appearance of a bimodal size distribution or the coexistence of elongated coil and shrunken globular states. The effective volume of the loosely shrunken state induced by Fis is 30–60 times larger than that of the compact state induced by spermidine, suggesting that cellular enzymes can access for DNA with the shrunken state but cannot for the compact state. Interestingly, Dps tends to inhibit the Fis-induced shrinkage of DNA, but promotes DNA compaction in the presence of spermidine. These characteristic effects of nucleotide proteins on a giant DNA are discussed by adopting a simple theoretical model with a mean-field approximation. 相似文献