首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2691篇
  免费   242篇
  国内免费   35篇
耳鼻咽喉   25篇
儿科学   195篇
妇产科学   43篇
基础医学   349篇
口腔科学   116篇
临床医学   244篇
内科学   599篇
皮肤病学   64篇
神经病学   151篇
特种医学   210篇
外科学   408篇
综合类   43篇
预防医学   186篇
眼科学   51篇
药学   105篇
中国医学   2篇
肿瘤学   177篇
  2023年   23篇
  2022年   35篇
  2021年   44篇
  2020年   29篇
  2019年   32篇
  2018年   80篇
  2017年   69篇
  2016年   68篇
  2015年   88篇
  2014年   117篇
  2013年   151篇
  2012年   112篇
  2011年   95篇
  2010年   126篇
  2009年   130篇
  2008年   101篇
  2007年   124篇
  2006年   96篇
  2005年   91篇
  2004年   76篇
  2003年   66篇
  2002年   68篇
  2001年   60篇
  2000年   38篇
  1999年   48篇
  1998年   112篇
  1997年   95篇
  1996年   104篇
  1995年   68篇
  1994年   80篇
  1993年   42篇
  1992年   29篇
  1991年   34篇
  1990年   29篇
  1989年   38篇
  1988年   32篇
  1987年   37篇
  1986年   39篇
  1985年   33篇
  1984年   25篇
  1983年   12篇
  1982年   23篇
  1981年   21篇
  1980年   19篇
  1979年   15篇
  1977年   13篇
  1976年   16篇
  1975年   16篇
  1973年   8篇
  1968年   9篇
排序方式: 共有2968条查询结果,搜索用时 15 毫秒
81.
Neurological Sciences - Optimal reperfusion strategies for M2 occlusion are still uncertain, with previous studies questioning benefit of mechanical thrombectomy (MT) over intravenous thrombolysis...  相似文献   
82.
83.
84.
85.
Cerebral white matter lesions (WMLs) are related to cognitive deficits, probably due to a disruption of frontal–subcortical circuits. We explored thalamic diffusion differences related to white matter lesions (WMLs) and their association with cognitive function in middle-aged individuals. Ninety-six participants from the Barcelona-AsIA Neuropsychology Study were included. Participants were classified into groups based on low grade and high grade of periventricular hyperintensities (PVHs) and deep white matter hyperintensities (DWMHs). Tract-Based Spatial Statistics was used to study thalamic diffusion differences between groups. Mean fractional anisotropy (FA) values in significant areas were calculated for each subject and correlated with cognitive performance. Participants with high-grade PVHs and DWMHs showed lower FA thalamic values compared to those with low-grade PVHs and DWMHs, respectively. Decreased FA thalamic values in high-grade DWMHs, but not high-grade PVH, were related to lower levels of performance in psychomotor speed, verbal fluency, and visuospatial skills. Thalamic diffusion differences are related to lower cognitive function only in participants with high-grade DWMHs. These results support the hypothesis that fronto–subcortical disruption is associated with cognitive function only in DWMHs.  相似文献   
86.
87.
Peripheral mononuclear cells (MNC) collected from 12 healthy donors and 44 leukemic patients at various stages of the disease were tested for natural killer (NK) activity and for their susceptibility to HTLV-I infection in vitro, measured in terms of percentage of p19 positive cells. MNC from leukemic donors at any stage of leukemia (ie, onset or relapse, ON/REL; complete remission or off-therapy, CR/OT donors) were highly susceptible to HTLV-I infection. This was true for acute leukemias of lymphoblastic (ALL) or nonlymphoblastic (ANLL) type. MNC of ON/REL patients were more susceptible to HTLV-I than those of CR/OT donors. In addition, leukemic blasts were more rapidly infected (ie, within five to seven days) than the HTLV-I-susceptible normal cord- blood lymphocytes. However, the presence of circulating blasts was not essential to virus susceptibility, since CR/OT MNC, presumably free of leukemic blasts, were still more susceptible to HTLV-I than normal cells. Basal NK function of MNC from leukemic patients was significantly lower than that detectable in healthy controls. However, no correlation was found between susceptibility to HTLV-I infection and NK activity.  相似文献   
88.
Components of the anti-Müllerian hormone signaling pathway in gonads   总被引:1,自引:0,他引:1  
Anti-Müllerian hormone (AMH) is a member of the Transforming Growth Factor-beta (TGF-beta) family implicated in the regression of Müllerian ducts in male fetuses and in the development and function of gonads of both sexes. Members of the TGF-beta family signal through two types of serine/threonine kinase receptors called type I and type II, and two types of Smad proteins, receptor-regulated Smad (R-Smad) and common Smad, Smad4. Components of the AMH signaling pathway have been identified in gonads and gonadal cell lines. The AMH type II receptor is highly specific. In contrast, the identity of the AMH type I receptor is not clear; three type I receptors of Bone Morphogenetic Proteins (BMPs), Alk2, Alk3 and Alk6 may transduce AMH signals, but none of them has all the characteristics of an AMH type I receptor. AMH activates BMP-specific R-Smads and reporter genes.  相似文献   
89.
Abstract Hyperdynamic circulation and portal hypertension characterize acute on chronic liver failure (AoCLF), partially because of circulating mediators. Molecular Absorbents Recirculating System (MARS) may remove some of these substances. The objective of this study was to evaluate the effect of MARS on portal pressure, systemic haemodynamic and endogenous vasoactive systems. MARS treatment was performed in four patients with AoCLF (mean age 36.2 ± 3.1 years; Child–Pugh C 11 ± 1.8 points; three AAH and one NASH). Systemic and splanchnic haemodynamic measurements were performed before and after each session. Plasmatic renin activity (PRA) and NE were measured at baseline, at the end of the sessions and 10 days after MARS. All patients had severe portal hypertension (HVPG = 23 ± 7 mmHg) and pronounced hyperdynamic circulation (MAP 77.8 ± 11.7 mmHg; CO 11.2 ± 1.6 L/min; SVRI 478.5 ± 105 dyne s/cm5). HVPG decreased at the end of the first session in all patients (23 ± 7 mmHg vs 17.3 ± 9.9 mmHg; P = 0.05; mean decrease 32 ± 24%) because of a decrease in WHVP (40.7 ± 5.6 mmHg vs 34 ± 9.6 mmHg; P = 0.025; mean decrease 18 ± 19%). MARS significantly attenuated hyperdynamic circulation as shown by a decrease in CO (11.2 ± 1.6 L/min vs 9.4 ± 2.1 L/min; mean decrease 12.3%), with an increase in MAP (77.8 ± 11.7 mmHg vs 84.2 ± 8 mmHg; mean increase 9.2%) and in SVRI (478.5 ± 105 dyne s/cm5 vs 622 ± 198 dyne s/cm5; mean increase 41%). PRA and NE decreased significantly (14.2 ± 17.2 ng/mL/h vs 3.7 ± 3.4 ng/mL/h; 1319 ± 1002 pg/mL vs 617 ± 260 pg/mL, respectively). The NE decrease was correlated to HVPG decrease (r = 1, P = 0.01). MARS decreases portal hypertension and ameliorates hyperdynamic circulation in patients with AoCLF, probably mediated by clearance of vasoactive substances. Further studies are necessary to confirm these results.  相似文献   
90.

Background:

Monoamine reuptake inhibitors exhibit unique clinical profiles that reflect distinct engagement of the central nervous system (CNS) transporters.

Methods:

We used a translational strategy, including rodent pharmacokinetic/pharmacodynamic modeling and positron emission tomography (PET) imaging in humans, to establish the transporter profile of TD-9855, a novel norepinephrine and serotonin reuptake inhibitor.

Results:

TD-9855 was a potent inhibitor of norepinephrine (NE) and serotonin 5-HT uptake in vitro with an inhibitory selectivity of 4- to 10-fold for NE at human and rat transporters. TD-9855 engaged norepinephrine transporters (NET) and serotonin transporters (SERT) in rat spinal cord, with a plasma EC50 of 11.7ng/mL and 50.8ng/mL, respectively, consistent with modest selectivity for NET in vivo.Accounting for species differences in protein binding, the projected human NET and SERT plasma EC50 values were 5.5ng/mL and 23.9ng/mL, respectively. A single-dose, open-label PET study (4–20mg TD-9855, oral) was conducted in eight healthy males using the radiotracers [11C]-3-amino-4- [2-[(di(methyl)amino)methyl]phenyl]sulfanylbenzonitrile for SERT and [11C]-(S,S)-methylreboxetine for NET. The long pharmacokinetic half-life (30–40h) of TD-9855 allowed for sequential assessment of SERT and NET occupancy in the same subject. The plasma EC50 for NET was estimated to be 1.21ng/mL, and at doses of greater than 4mg the projected steady-state NET occupancy is high (>75%). After a single oral dose of 20mg, SERT occupancy was 25 (±8)% at a plasma level of 6.35ng/mL.

Conclusions:

These data establish the CNS penetration and transporter profile of TD-9855 and inform the selection of potential doses for future clinical evaluation.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号