全文获取类型
收费全文 | 12937篇 |
免费 | 1204篇 |
国内免费 | 14篇 |
出版年
2023年 | 63篇 |
2022年 | 97篇 |
2021年 | 193篇 |
2020年 | 157篇 |
2019年 | 188篇 |
2018年 | 204篇 |
2017年 | 167篇 |
2016年 | 276篇 |
2015年 | 506篇 |
2014年 | 565篇 |
2013年 | 646篇 |
2012年 | 844篇 |
2011年 | 856篇 |
2010年 | 564篇 |
2009年 | 505篇 |
2008年 | 723篇 |
2007年 | 740篇 |
2006年 | 701篇 |
2005年 | 664篇 |
2004年 | 615篇 |
2003年 | 594篇 |
2002年 | 543篇 |
2001年 | 162篇 |
2000年 | 144篇 |
1999年 | 191篇 |
1998年 | 187篇 |
1997年 | 127篇 |
1996年 | 122篇 |
1995年 | 139篇 |
1994年 | 106篇 |
1993年 | 99篇 |
1992年 | 111篇 |
1991年 | 119篇 |
1990年 | 120篇 |
1989年 | 98篇 |
1988年 | 90篇 |
1987年 | 75篇 |
1986年 | 86篇 |
1985年 | 84篇 |
1984年 | 82篇 |
1983年 | 76篇 |
1982年 | 92篇 |
1981年 | 94篇 |
1980年 | 83篇 |
1979年 | 68篇 |
1978年 | 58篇 |
1977年 | 51篇 |
1976年 | 66篇 |
1975年 | 61篇 |
1974年 | 63篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
1.
2.
3.
4.
5.
6.
Susan Morrison Grace John-Stewart John J. Egessa Sezi Mubezi Sylvia Kusemererwa Dennis K. Bii Nulu Bulya Francis Mugume James D. Campbell Jonathan Wangisi Elizabeth A. Bukusi Connie Celum Jared M. Baeten Partners PrEP Study Team 《PloS one》2015,10(10)
During an HIV-1 prevention clinical trial in East Africa, we observed 16 cases of primary HIV-1 infection in women coincident with pregnancy or breastfeeding. Nine of eleven pregnant women initiated rapid combination antiretroviral therapy (ART), despite having CD4 counts exceeding national criteria for ART initiation; breastfeeding women initiated ART or replacement feeding. Rapid ART initiation during primary HIV-1 infection during pregnancy and breastfeeding is feasible in this setting. 相似文献
7.
During the process optimisation of glucoamylase production by Aspergillus awamori, cell morphology was controlled at such a state that spore aggregation was completely prevented. Samples from five fermentations on complex media using either glucose or starch as carbon source were characterised with a Bohlin CS rheometer. The experimental data were conveniently described in terms of the power law model. 相似文献
8.
Electrical stimulation of the nervous system for therapeutic purposes, such as deep brain stimulation in the treatment of Parkinson’s disease, has been used for decades. Recently, increased attention has focused on using microstimulation to restore functions as diverse as somatosensation and memory. However, how microstimulation changes the neural substrate is still not fully understood. Microstimulation may cause cortical changes that could either compete with or complement natural neural processes, and could result in neuroplastic changes rendering the region dysfunctional or even epileptic. As part of our efforts to produce neuroprosthetic devices and to further study the effects of microstimulation on the cortex, we stimulated and recorded from microelectrode arrays in the hand area of the primary somatosensory cortex (area 1) in two awake macaque monkeys. We applied a simple neuroprosthetic microstimulation protocol to a pair of electrodes in the area 1 array, using either random pulses or pulses time-locked to the recorded spiking activity of a reference neuron. This setup was replicated using a computer model of the thalamocortical system, which consisted of 1980 spiking neurons distributed among six cortical layers and two thalamic nuclei. Experimentally, we found that spike-triggered microstimulation induced cortical plasticity, as shown by increased unit-pair mutual information, while random microstimulation did not. In addition, there was an increased response to touch following spike-triggered microstimulation, along with decreased neural variability. The computer model successfully reproduced both qualitative and quantitative aspects of the experimental findings. The physiological findings of this study suggest that even simple microstimulation protocols can be used to increase somatosensory information flow. 相似文献
9.
Colin K.W. Watts Robert L. Sutherland 《Biochemical and biophysical research communications》1984,120(1):109-115
Saturation and competitive binding analyses demonstrated the presence of a high affinity (KD = 0.92 nM), specific antiestrogen binding site (AEBS) in rat liver microsomes and at least 75% of total liver AEBS was recovered in this fraction. When microsomes were further separated into smooth and rough fractions, AEBS was concentrated in the latter. Subsequent dissociation of ribosomes from the rough membranes revealed that AEBS was associated with the membrane and not the ribosomal fraction. Antiestrogen binding activity could not be extracted from membranes with 1 M KCl or 0.5 M acetic acid but could be solubilized with sodium cholate. These data indicate that AEBS is an integral membrane component of the rough microsomal fraction of rat liver. 相似文献
10.