全文获取类型
收费全文 | 1686067篇 |
免费 | 115710篇 |
国内免费 | 4887篇 |
专业分类
耳鼻咽喉 | 20079篇 |
儿科学 | 54856篇 |
妇产科学 | 43244篇 |
基础医学 | 239038篇 |
口腔科学 | 41525篇 |
临床医学 | 158234篇 |
内科学 | 325350篇 |
皮肤病学 | 29520篇 |
神经病学 | 144734篇 |
特种医学 | 63175篇 |
外国民族医学 | 379篇 |
外科学 | 242788篇 |
综合类 | 34367篇 |
现状与发展 | 3篇 |
一般理论 | 736篇 |
预防医学 | 147160篇 |
眼科学 | 35357篇 |
药学 | 120479篇 |
7篇 | |
中国医学 | 4081篇 |
肿瘤学 | 101552篇 |
出版年
2021年 | 13558篇 |
2019年 | 14410篇 |
2018年 | 41059篇 |
2017年 | 32088篇 |
2016年 | 36330篇 |
2015年 | 19456篇 |
2014年 | 26584篇 |
2013年 | 40135篇 |
2012年 | 61595篇 |
2011年 | 79232篇 |
2010年 | 51742篇 |
2009年 | 42680篇 |
2008年 | 73968篇 |
2007年 | 80461篇 |
2006年 | 57196篇 |
2005年 | 58197篇 |
2004年 | 57229篇 |
2003年 | 56139篇 |
2002年 | 52367篇 |
2001年 | 62874篇 |
2000年 | 64468篇 |
1999年 | 54271篇 |
1998年 | 17212篇 |
1997年 | 15641篇 |
1996年 | 15163篇 |
1995年 | 14303篇 |
1994年 | 13251篇 |
1993年 | 12363篇 |
1992年 | 42607篇 |
1991年 | 41864篇 |
1990年 | 40481篇 |
1989年 | 38258篇 |
1988年 | 35507篇 |
1987年 | 34675篇 |
1986年 | 33067篇 |
1985年 | 31654篇 |
1984年 | 24297篇 |
1983年 | 20829篇 |
1982年 | 13307篇 |
1981年 | 11619篇 |
1979年 | 21519篇 |
1978年 | 15631篇 |
1977年 | 12820篇 |
1976年 | 12595篇 |
1975年 | 12659篇 |
1974年 | 15391篇 |
1973年 | 14961篇 |
1972年 | 13729篇 |
1971年 | 12717篇 |
1970年 | 11788篇 |
排序方式: 共有10000条查询结果,搜索用时 500 毫秒
61.
62.
63.
Autoimmune comorbid diseases associated with lichen planus: a nationwide case–control study 下载免费PDF全文
64.
65.
66.
Seyed Mehdi BagheriMofidi Majid Pouladian Seyed Behnamedin Jameie Ali Abbaspour Tehrani-Fard 《Australasian physical & engineering sciences in medicine / supported by the Australasian College of Physical Scientists in Medicine and the Australasian Association of Physical Sciences in Medicine》2016,39(3):717-726
Magnetic field generated by neuronal activity could alter magnetic resonance imaging (MRI) signals but detection of such signal is under debate. Previous researches proposed that magnitude signal change is below current detectable level, but phase signal change (PSC) may be measurable with current MRI systems. Optimal imaging parameters like echo time, voxel size and external field direction, could increase the probability of detection of this small signal change. We simulate a voxel of cortical column to determine effect of such parameters on PSC signal. We extended a laminar network model for somatosensory cortex to find neuronal current in each segment of pyramidal neurons (PN). 60,000 PNs of simulated network were positioned randomly in a voxel. Biot–savart law applied to calculate neuronal magnetic field and additional phase. The procedure repeated for eleven neuronal arrangements in the voxel. PSC signal variation with the echo time and voxel size was assessed. The simulated results show that PSC signal increases with echo time, especially 100/80 ms after stimulus for gradient echo/spin echo sequence. It can be up to 0.1 mrad for echo time = 175 ms and voxel size = 1.48 × 1.48 × 2.18 mm3. With echo time less than 25 ms after stimulus, it was just acquired effects of physiological noise on PSC signal. The absolute value of the signal increased with decrease of voxel size, but its components had complex variation. External field orthogonal to local surface of cortex maximizes the signal. Expected PSC signal for tactile detection in the somatosensory cortex increase with echo time and have no oscillation. 相似文献
67.
Ki-Yong An Andria R. Morielli Dong-Woo Kang Christine M. Friedenreich Donald C. McKenzie Karen Gelmon John R. Mackey Robert D. Reid Kerry S. Courneya 《International journal of cancer. Journal international du cancer》2020,146(1):150-160
The Combined Aerobic and Resistance Exercise (CARE) Trial compared different types and doses of exercise performed during breast cancer chemotherapy. Here, we report the longer-term follow-up of patient-reported outcomes, health-related fitness and exercise behavior at 6, 12 and 24 months postintervention. A multicenter trial in Canada randomized 301 breast cancer patients initiating chemotherapy to thrice weekly, supervised exercise consisting of a standard dose of 25–30 min of aerobic exercise (STAN; n = 96), a higher dose of 50–60 min of aerobic exercise (HIGH; n = 101) or a combined dose of 50–60 min of aerobic and resistance exercise (COMB; n = 104) performed for the duration of chemotherapy (median of 17 weeks). Primary outcomes were patient-reported outcomes including quality of life, cancer-related symptoms and psychosocial outcomes. Secondary outcomes were objective health-related fitness (assessed at 12 months only) and self-reported exercise behavior. A total of 269 (89.4%) participants completed patient-reported outcomes at all three follow-up time points and 263 (87.4%) completed the health-related fitness assessment at 12-month follow-up. COMB was significantly superior to (i) STAN for sleep quality at 6-month follow-up (p = 0.027); (ii) HIGH for upper body muscular endurance at 12-month follow-up (p = 0.020); and (iii) HIGH for meeting the resistance exercise guideline at 6-month follow-up (p = 0.006). Moreover, self-reported meeting of the combined exercise guideline during follow-up was significantly associated with better patient-reported outcomes and health-related fitness. Performing combined exercise during and after breast cancer chemotherapy may result in better longer-term patient-reported outcomes and health-related fitness compared to performing aerobic exercise alone. 相似文献
68.
69.
Y.R. Song B. Wu Y.T. Yang J. Chen L.J. Zhang Z.W. Zhang H.Y. Shi C.L. Huang J.X. Pan P. Xie 《Brazilian journal of medical and biological research》2015,48(11):973-982
Bipolar disorder (BD) is a common psychiatric mood disorder affecting more than 1-2%
of the general population of different European countries. Unfortunately, there is no
objective laboratory-based test to aid BD diagnosis or monitor its progression, and
little is known about the molecular basis of BD. Here, we performed a comparative
proteomic study to identify differentially expressed plasma proteins in various BD
mood states (depressed BD, manic BD, and euthymic BD) relative to healthy controls. A
total of 10 euthymic BD, 20 depressed BD, 15 manic BD, and 20 demographically matched
healthy control subjects were recruited. Seven high-abundance proteins were
immunodepleted in plasma samples from the 4 experimental groups, which were then
subjected to proteome-wide expression profiling by two-dimensional electrophoresis
and matrix-assisted laser desorption/ionization-time-of-flight/time-of-flight tandem
mass spectrometry. Proteomic results were validated by immunoblotting and
bioinformatically analyzed using MetaCore. From a total of 32 proteins identified
with 1.5-fold changes in expression compared with healthy controls, 16 proteins were
perturbed in BD independent of mood state, while 16 proteins were specifically
associated with particular BD mood states. Two mood-independent differential
proteins, apolipoprotein (Apo) A1 and Apo L1, suggest that BD pathophysiology may be
associated with early perturbations in lipid metabolism. Moreover, down-regulation of
one mood-dependent protein, carbonic anhydrase 1 (CA-1), suggests it may be involved
in the pathophysiology of depressive episodes in BD. Thus, BD pathophysiology may be
associated with early perturbations in lipid metabolism that are independent of mood
state, while CA-1 may be involved in the pathophysiology of depressive episodes. 相似文献
70.
John Bickle 《Topics in Cognitive Science》2015,7(2):299-311
David Marr's three-level method for completely understanding a cognitive system and the importance he attaches to the computational level are so familiar as to scarcely need repeating. Fewer seem to recognize that Marr defends his famous method by criticizing the “reductionistic approach.” This sets up a more interesting relationship between Marr and reductionism than is usually acknowledged. I argue that Marr was correct in his criticism of the reductionists of his time—they were only describing (cellular activity), not explaining (cognitive functions). But a careful metascientific account of reductionistic neuroscience over the past two decades reveals that Marr's criticisms no longer have force. Contemporary neuroscience now explains cognition directly, although in a fashion—causal-mechanistically—quite different than Marr recommended. So while Marr was correct to reject the reductionism of his day and offer an alternative method for genuinely explaining cognition, contemporary cognitive scientists now owe us a new defense of Marr's famous method and the advantages of its explanations over the type now pursued successfully in current reductionist neuroscience. There are familiar reasons for thinking that this debt will not be paid easily. 相似文献