全文获取类型
收费全文 | 957篇 |
免费 | 73篇 |
国内免费 | 2篇 |
出版年
2024年 | 2篇 |
2023年 | 5篇 |
2022年 | 20篇 |
2021年 | 45篇 |
2020年 | 31篇 |
2019年 | 45篇 |
2018年 | 40篇 |
2017年 | 33篇 |
2016年 | 36篇 |
2015年 | 53篇 |
2014年 | 59篇 |
2013年 | 74篇 |
2012年 | 71篇 |
2011年 | 84篇 |
2010年 | 41篇 |
2009年 | 34篇 |
2008年 | 37篇 |
2007年 | 41篇 |
2006年 | 33篇 |
2005年 | 23篇 |
2004年 | 22篇 |
2003年 | 18篇 |
2002年 | 18篇 |
2001年 | 19篇 |
2000年 | 12篇 |
1999年 | 16篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 11篇 |
1989年 | 4篇 |
1988年 | 12篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1975年 | 3篇 |
1974年 | 6篇 |
1973年 | 3篇 |
1965年 | 1篇 |
排序方式: 共有1032条查询结果,搜索用时 171 毫秒
61.
A new design of insecticide testing assembly has been devised that is highly versatile in testing the efficacy, potency and interaction of insecticides and other test chemicals. The merits of the assembly and technique have been explained. 相似文献
62.
63.
64.
Scatter factor/hepatocyte growth factor stimulation of glioblastoma cell cycle progression through G(1) is c-Myc dependent and independent of p27 suppression, Cdk2 activation, or E2F1-dependent transcription 下载免费PDF全文
Walter KA Hossain MA Luddy C Goel N Reznik TE Laterra J 《Molecular and cellular biology》2002,22(8):2703-2715
65.
A comparative study of two modifications of enzymic reduction of ethyl N-{2-{4-[(2-oxo-cyclohexyl)methyl]phe- noxy}ethyl} carbamate (1), an insect juvenile hormone bioanalog, was performed using Saccharomyces cerevisiae in two bioreactors of different size, 250-ml shake-flask and 1-l fermenter. The two major products of this reduction were obtained in 45–49% (w/w) yields but with > 99% enantiomeric purity. Their absolute configurations were assigned as ethyl (1S,2S)-N-{2-{4-[(2-hydroxycyclohexyl)methyl]phenoxy}ethyl}carbamate (2a) and ethyl (1R,2S)-N-{2-{4-[(2-hydroxycyclohexyl)methyl]phenoxy}ethyl}carbamate (3a). 相似文献
66.
Quinapril inhibits progression of heart failure and fibrosis in rats with dilated cardiomyopathy after myocarditis 总被引:7,自引:0,他引:7
Juan W Nakazawa M Watanabe K Ma M Wahed MI Hasegawa G Naito M Yamamoto T Fuse K Kato K Kodama M Aizawa Y 《Molecular and cellular biochemistry》2003,251(1-2):77-82
The cardioprotective properties of quinapril, an angiotensin-converting enzyme inhibitor, were studied in a rat model of dilated cardiomyopathy. Twenty-eight days after immunization of pig cardiac myosin, four groups rats were given 0.2 mg/kg (Q0.2, n = 11), 2 mg/kg (Q2, n = 11) or 20 mg/kg (Q20, n = 11) of quinapril or vehicle (V, n = 15) orally once a day. After 1 month, left ventricular end-diastolic pressure (LVEDP), ±dP/dt, area of myocardial fibrosis, and myocardial mRNA expression of transforming growth factor (TGF)-1, collagen-III and fibronectin were measured. Four of 15 (27%) rats in V and two of 11 (18%) in Q0.2 died. None of the animals in Q2 or Q20 died. The LVEDP was higher and ±dP/dt was lower in V (14.1 ± 2.0 mmHg and +2409 ± 150/–2318 ± 235 mmHg/sec) than in age-matched normal rats (5.0 ± 0.6 mmHg and +6173 ± 191/–7120 ± 74 mmHg/sec; all p < 0.01). After quinapril treatment, LVEDP was decreased and ±dP/dt was increased in a dose-dependent manner (10.8 ± 1.8 mmHg and +3211 ± 307/–2928 ± 390 mmHg/sec in Q0.2, 9.4 ± 1.5 mmHg and +2871 ± 270/–2966 ± 366 mmHg/sec in Q2, and 6.6 ± 1.5 mmHg, and +3569 ± 169/–3960 ± 203 mmHg/sec in Q20). Increased expression levels of TGF-1, collagen-III and fibronectin mRNA in V were reduced in Q20. Quinapril improved survival rate and cardiac function in rats with dilated cardiomyopathy after myocarditis. Furthermore, myocardial fibrosis was regressed and myocardial structure returned to nearly normal in animals treated with quinapril. 相似文献
67.
The hammerhead ribozyme is able to cleave RNA in a sequence-specific manner. These ribozymes are usually designed with four
basepairs in helix II, and with equal numbers of nucleotides in the 5′ and 3′ hybridizing arms that bind the RNA substrate
on either side of the cleavage site. Here guidelines are given for redesigning the ribozyme so that it is small, but retains
efficient cleavage activity. First, the ribozyme may be reduced in size by shortening the 5′ arm of the ribozyme to five or
six nucleotides; for these ribozymes, cleavage of short substrates is maximal. Second, the internal double-helix of the ribozyme
(helix II) may be shortened to one or no basepairs, forming a miniribozyme or minizyme, respectively. The sequence of the
shortened helix+loop II greatly affects cleavage rates. With eight or more nucleotides in both the 5′ and the 3′ arms of a
miniribozyme containing an optimized sequence for helix+loop II, cleavage rates of short substrates are greater than for analogous
ribozymes possessing a longer helix II. Cleavage of genelength RNA substrates may be best achieved by miniribozymes. 相似文献
68.
Gene transfer using electrical pulses is a rapidly expanding field. Many studies have been performed in vitro to elucidate the mechanism of DNA electrotransfer. In vivo, the use of efficient procedures for DNA electrotransfer in tissues is recent, and the question of the implied mechanisms is largely open. We have evaluated the effects of various combinations of square wave electric pulses of variable field strength and duration, on cell permeabilization and on DNA transfection in the skeletal muscle in vivo. One high voltage pulse of 800 V/cm, 0.1 ms duration (short high pulse) or a series of four low voltage pulses of 80 V/cm, 83 ms duration (long low pulses) slightly amplified transfection efficacy, while no significant permeabilization was detected using the (51)Cr-EDTA uptake test. By contrast, the combination of one short high pulse followed by four long low pulses led to optimal gene transfer efficiency, while inducing muscle fibers permeabilization. These results are consistent with additive effects of electropermeabilization and DNA electrophoresis on electrotransfer efficiency. Finally, the described new combination, as compared to the previously reported use of repeated identical pulses of intermediate voltage, leads to similar gene transfer efficiency, while causing less permeabilization and thus being likely less deleterious. Thus, combination of pulses of various strengths and durations is a new procedure for skeletal muscle gene transfer that may represents a clear improvement in view of further clinical development. 相似文献
69.
Carmen S. M. Yong Janelle Sharkey Belinda Duscio Ben Venville Wei-Zen Wei Richard F. Jones Clare Y. Slaney Gisela Mir Arnau Anthony T. Papenfuss Jan Schr?der Phillip K. Darcy Michael H. Kershaw 《PloS one》2015,10(9)
The development of antigen-targeted therapeutics is dependent on the preferential expression of tumor-associated antigens (TAA) at targetable levels on the tumor. Tumor-associated antigens can be generated de novo or can arise from altered expression of normal basal proteins, such as the up-regulation of human epidermal growth factor receptor 2 (Her2/ErbB2). To properly assess the development of Her2 therapeutics in an immune tolerant model, we previously generated a transgenic mouse model in which expression of the human Her2 protein was present in both the brain and mammary tissue. This mouse model has facilitated the development of Her2 targeted therapies in a clinically relevant and suitable model. While heterozygous Her2+/- mice appear to develop in a similar manner to wild type mice (Her2-/-), it has proven difficult to generate homozygous Her2+/+ mice, potentially due to embryonic lethality. In this study, we performed whole genome sequencing to determine if the integration site of the Her2 transgene was responsible for this lethality. Indeed, we report that the Her2 transgene had integrated into the Pds5b (precocious dissociation of sisters) gene on chromosome 5, as a 162 copy concatemer. Furthermore, our findings demonstrate that Her2+/+ mice, similar to Pds5b-/- mice, are embryonic lethal and confirm the necessity for Pds5b in embryonic development. This study confirms the value of whole genome sequencing in determining the integration site of transgenes to gain insight into associated phenotypes. 相似文献
70.
Lori Newman Jane Rowley Stephen Vander Hoorn Nalinka Saman Wijesooriya Magnus Unemo Nicola Low Gretchen Stevens Sami Gottlieb James Kiarie Marleen Temmerman 《PloS one》2015,10(12)