全文获取类型
收费全文 | 38434篇 |
免费 | 3721篇 |
国内免费 | 17篇 |
专业分类
42172篇 |
出版年
2022年 | 240篇 |
2021年 | 539篇 |
2020年 | 315篇 |
2019年 | 437篇 |
2018年 | 501篇 |
2017年 | 464篇 |
2016年 | 751篇 |
2015年 | 1180篇 |
2014年 | 1375篇 |
2013年 | 1809篇 |
2012年 | 2138篇 |
2011年 | 2240篇 |
2010年 | 1402篇 |
2009年 | 1319篇 |
2008年 | 1961篇 |
2007年 | 2061篇 |
2006年 | 1943篇 |
2005年 | 1962篇 |
2004年 | 1896篇 |
2003年 | 1886篇 |
2002年 | 1801篇 |
2001年 | 522篇 |
2000年 | 366篇 |
1999年 | 484篇 |
1998年 | 537篇 |
1997年 | 373篇 |
1996年 | 404篇 |
1995年 | 337篇 |
1994年 | 356篇 |
1993年 | 344篇 |
1992年 | 357篇 |
1991年 | 326篇 |
1990年 | 330篇 |
1989年 | 299篇 |
1988年 | 314篇 |
1987年 | 303篇 |
1986年 | 266篇 |
1985年 | 346篇 |
1984年 | 432篇 |
1983年 | 364篇 |
1982年 | 405篇 |
1981年 | 470篇 |
1980年 | 440篇 |
1979年 | 299篇 |
1978年 | 288篇 |
1977年 | 310篇 |
1976年 | 299篇 |
1975年 | 224篇 |
1974年 | 262篇 |
1973年 | 229篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
32.
33.
William Russell 《BMJ (Clinical research ed.)》1984,288(6429):1546
34.
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
35.
36.
37.
P.Mick Richardson 《Biochemical Systematics and Ecology》1982,10(2):197-199
Published results of the distribution of anthocyanins in the Sterculiaceae have been re-interpreted on the basis of the phylogenetic status of the compounds present. A flavonoid score system was less useful than a cladistic interpretation based on Hennigian arguments. 相似文献
38.
A monoclonal antibody (RBU/01) was raised against human thyroglobulin and its suitability for the immunohistochemical staining of thyroglobulin was determined on fixed, wax-embedded tissue, using the peroxidase anti-peroxidase (PAP) method. The antibody was then used to demonstrate the expression of human thyroglobulin in sections of a human follicular carcinoma of the thyroid which had been grown in immunodeficient mice. It is concluded that the immunohistochemical evaluation of the xenografts with the antibody provides useful information on this xenograft system as a potential model for thyroid carcinoma. 相似文献
39.
Eileen M. Proctor Judith L. Isaac-Renton William B. Robertson William A. Black 《CMAJ》1985,133(9):876-878
A survey was done of Canadians who had been interned by the Japanese during World War II to assess the prevalence of latent infection with Strongyloides stercoralis in this group. Packages containing three mail-in kits and a questionnaire were sent to 992 men, 694 (70%) of whom responded. Larvae were found in the stool specimens of four of the respondents. Examination of stool specimens after formalin-ether concentration was the most successful method of detecting Strongyloides larvae. The Baermann concentration technique yielded negative results in all four men. Three of the four cases of strongyloidiasis were detected after sampling of three fecal specimens. In the fourth case additional specimens were requested on the basis of data derived from the questionnaire. The most frequently cited clinical manifestations were abdominal pain, weight loss, diarrhea and rashes. 相似文献
40.