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   9493篇
  免费   771篇
  国内免费   150篇
耳鼻咽喉   100篇
儿科学   182篇
妇产科学   391篇
基础医学   1219篇
口腔科学   199篇
临床医学   981篇
内科学   1926篇
皮肤病学   137篇
神经病学   628篇
特种医学   349篇
外科学   1377篇
综合类   328篇
现状与发展   1篇
一般理论   2篇
预防医学   454篇
眼科学   193篇
药学   960篇
  4篇
中国医学   194篇
肿瘤学   789篇
  2023年   95篇
  2022年   144篇
  2021年   286篇
  2020年   185篇
  2019年   284篇
  2018年   318篇
  2017年   216篇
  2016年   200篇
  2015年   316篇
  2014年   387篇
  2013年   504篇
  2012年   678篇
  2011年   778篇
  2010年   486篇
  2009年   384篇
  2008年   551篇
  2007年   524篇
  2006年   507篇
  2005年   490篇
  2004年   429篇
  2003年   351篇
  2002年   315篇
  2001年   253篇
  2000年   213篇
  1999年   181篇
  1998年   78篇
  1997年   59篇
  1996年   43篇
  1995年   65篇
  1994年   56篇
  1993年   54篇
  1992年   126篇
  1991年   100篇
  1990年   91篇
  1989年   69篇
  1988年   69篇
  1987年   70篇
  1986年   39篇
  1985年   42篇
  1984年   47篇
  1983年   30篇
  1982年   32篇
  1981年   21篇
  1980年   23篇
  1979年   25篇
  1978年   21篇
  1977年   22篇
  1976年   23篇
  1975年   22篇
  1972年   17篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.

Background

The presence of subtle losses in hand dexterity after stroke affects the regaining of independence with regard to activities of daily living. Therefore, awareness of ipsilesional upper extremity (UE) function may be of importance when developing a comprehensive rehabilitation program. However, current hand function tests seem to be unable to identify asymptomatic UE impairments.

Objectives

To assess the motor coordination as well as the sensory perception of an ipsilesional UE using biomechanical analysis of performance-oriented tasks and conducting a Manual Tactile Test (MTT).

Design

Case-controlled study.

Setting

A university hospital.

Participants

A total of 21 patients with unilateral stroke, along with 21 matched healthy control subjects, were recruited.

Methods

Each participant was requested to perform a pinch?holding-up activity (PHUA) test, object-transport task, and reach-to-grasp task via motion capture, as well as the MTT.

Main Outcome Measurements

The kinetic data of the PHUA test, kinematics analysis of functional movements, and time requirement of MTT were analyzed.

Results

Patients with ipsilesional UE had an inferior ability to scale and produce pinch force precisely when conducting the PHUA test compared to the healthy controls (P < .05). The movement time was statistically longer and peak velocity was significantly lower (P < .05) in the performance-oriented tasks for the ipsilesional UE patients. The longer time requirement in 3 MTT subtests showed that the ipsilesional UE patients experienced degradation in sensory perception (P < .001).

Conclusion

Comprehensive sensorimotor assessments based on functional perspectives are valid tools to determine deficits in the sensation-perception-motor system in the ipsilesional UE. Integration of sensorimotor training programs for ipsilesional UE in future neuro-rehabilitation strategies may provide more beneficial effects to regain patients’ motor recovery and to promote daily living activity independence than focusing on paretic arm motor training alone.

Level of Evidence

III  相似文献   
992.
目的:探讨姜黄素衍生物64PH的体内外抗肿瘤活性。方法:MTT法检测64PH对小鼠B16黑色素瘤细胞及人HepG2肝癌细胞的体外增殖抑制作用;采用小鼠移植性肿瘤H22观察64PH的体内抑瘤活性,HE染色观察肿瘤血管新生。结果:64PH对B16 的IC50分别为10.30 μg·ml-1(24 h),3.12 μg·ml-1(48 h), 2.67 μg·ml-1(72 h),对HepG2的IC50分别为5.60 μg·ml-1(24 h),7.60 μg·ml-1(48 h),5.92 μg·ml-1(72 h);低剂量(100 mg·kg-1)、高剂量(300 mg·kg-1)64PH对小鼠H22的抑瘤率分别为26.1%,33.0%,且可明显抑制小鼠H22肿瘤的血管生成。结论:64PH在体内外均具有较好的抗肿瘤活性。  相似文献   
993.
The effects of striatal dopamine denervation and levodopa replacement therapy on neuronal populations in the rat striatum were assessed by measurement of glutamic acid decarboxylase (GAD) and choline acetyltransferase (CAT) activities in the striatum, dynorphin and substance P concentrations in the substantia nigra, and enkephalin concentration in the globus pallidus. Rats with a unilateral 6-hydroxydopamine (6-OHDA) lesion of the nigrostriatal pathway were treated for 21 days with levodopa (100 mg/kg/day, i.p., with 25 mg/kg benserazide) on either an intermittent (b.i.d.) or continuous (osmotic pump infusion) regimen and sacrificed following a three day drug washout. In saline-treated control rats, striatal GAD activity and globus pallidus enkephalin content were elevated and nigral substance P content was reduced ipsilateral to the 6-OHDA lesion. Intermittent levodopa treatment further increased GAD activity, decreased CAT activity, restored substance P to control levels, markedly increased dynorphin content, and had no effect on enkephalin. In contrast, continuous levodopa elevated globus pallidus enkephalin beyond the levels occurring with denervation, but had no effect on any of the other neurochemical measures. These results indicate that striatal neuronal populations are differentially affected by chronic levodopa therapy and by the continuous or intermittent nature of the treatment regimen. With the exception of substance P, levodopa did not reverse the effects of the 6-OHDA lesion but, rather, either exacerbated the lesion-induced changes (e.g. GAD and enkephalin) or altered neurochemical markers which had been unaffected by the lesion (e.g. CAT and dynorphin).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
994.

Background

Chronic kidney disease (CKD) affects many physiologic systems, including bone quality, nutrition, and cardiovascular condition. Femoral neck fractures in patients on dialysis are associated with frequent complications and a high risk of mortality. However, the effect of CKD on clinical outcomes of patients with hip fractures treated with osteosynthesis remains unclear.

Methods

One hundred and thirty patients with 130 femoral neck fractures treated with internal fixation were divided into two groups and the data were then analyzed. Group 1 consisted of 98 patients (98 hip fractures) with normal renal function (estimated glomerular filtration rate, or eGFR, ≥60 ml/min/1.73 m2). Group 2 was composed of 32 patients (32 hip fractures) with CKD (eGFR <60 ml/min/1.73 m2) without dialysis. Clinical outcomes as well as early and late complications were recorded for each group. Survivorship analysis was performed, and the mortality and complication rates for the groups were then compared.

Results

In Group 1, 32 complications (32.6 %) occurred in 98 hips, including 5 cases of nonunion and 16 cases of osteonecrosis. In Group 2, 24 complications (75 %) developed in 32 hips; these included 8 cases of nonunion and 3 cases of osteonecrosis. The mean duration of follow-up was 32 months. The overall mortality rate was 11.5 %. No difference was noted in early, late, or overall mortality rate between two groups. Patient with CKD had a higher nonunion rate (OR = 5.9, P = 0.023). Meanwhile, CKD and displaced fracture pattern were independent predictors for revision surgery (OR = 3.0, P = 0.032; OR = 6.9, P = 0.001, respectively).

Conclusions

Osteosynthesis is a safe and effective treatment for femoral neck fractures; however, patients with femoral neck fracture and CKD have a higher risk of nonunion and subsequent surgical revision.

Level of relevance

Prognostic studies, Level III.  相似文献   
995.

Background

Tranexamic acid (TXA) was reportedly to decrease postoperative blood loss after standard total knee arthroplasty (TKA). However, the blood-conservation effect of TXA in minimally invasive TKA, in particular, receiving a direct oral anticoagulant was unclear. The aim of the study was to investigate the efficacy of combined use of TXA and rivaroxaban on postoperative blood loss in primary minimally invasive TKA.

Methods

In a prospective, randomized, controlled trial, 198 patients were assigned to placebo (98 patients, normal saline injection) and study group (100 patients, 1g TXA intraoperative injection) during primary unilateral minimally invasive TKA. All patients received rivaroxaban 10 mg each day for 14 doses postoperatively. Total blood loss was calculated from the maximum hemoglobin drop after surgery plus amount of transfusion. The transfusion rate and wound complications were recorded in all patients. Deep-vein thrombosis was detected by ascending venography of the leg 15 days postoperatively.

Results

The mean total blood loss was lower in the study group (1020 mL [95% confidence interval, 960-1080 mL]) compared with placebo (1202 mL [95% confidence interval, 1137-1268 mL]) (P < .001). The transfusion rate was lower in the study group compared with placebo (1% vs 8.2%, P = .018). Postoperative wound hematoma and ecchymosis were higher in placebo than the study group (P = .003). There was no symptomatic deep-vein thrombosis or pulmonary embolism in either group.

Conclusion

Systemic administration of TXA can effectively reduce the postoperative blood loss which results in lower rate of transfusion requirement and wound hematoma in minimally invasive TKA patients when rivaroxaban is used for thromboprophylaxis. Rivaroxaban has a high rate of bleeding complications when used alone in TKA patients.  相似文献   
996.
BackgroundTranscranial direct current stimulation (tDCS) induces long-lasting NMDA receptor-dependent cortical plasticity via persistent subthreshold polarization of neuronal membranes. Conventional bipolar tDCS is applied with two large (35 cm2) rectangular electrodes, resulting in directional modulation of neuronal excitability. Recently a newly designed 4 × 1 high-definition (HD) tDCS protocol was proposed for more focal stimulation according to the results of computational modeling. HD tDCS utilizes small disc electrodes deployed in 4 × 1 ring configuration whereby the physiological effects of the induced electric field are thought to be grossly constrained to the cortical area circumscribed by the ring.ObjectiveWe aim to compare the physiological effects of both tDCS electrode arrangements on motor cortex excitability.MethodstDCS was applied with 2 mA for 10 min. Fourteen healthy subjects participated, and motor cortex excitability was monitored by transcranial magnetic stimulation (TMS) before and after tDCS.ResultsExcitability enhancement following anodal and a respective reduction after cathodal stimulation occurred in both, conventional and HD tDCS. However, the plastic changes showed a more delayed peak at 30 min and longer lasting after-effects for more than 2 h after HD tDCS for both polarities, as compared to conventional tDCS.ConclusionThe results show that this new electrode arrangement is efficient for the induction of neuroplasticity in the primary motor cortex. The pattern of aftereffects might be compatible with the concept of GABA-mediated surround inhibition, which should be explored in future studies directly.  相似文献   
997.
The role that collectin (mannose-binding protein) may play in the host’s defense against chlamydial infection was investigated. Recombinant human mannose-binding protein was used in the inhibition of cell culture infection by Chlamydia trachomatis (C/TW-3/OT, E/UW-5/Cx, and L2/434/Bu), Chlamydia pneumoniae (AR-39), and Chlamydia psittaci (6BC). Mannose-binding protein (MBP) inhibited infection of all chlamydial strains by at least 50% at 0.098 μg/ml for TW-3 and UW-5, and at 6.25 μg/ml for 434, AR-39, and 6BC. The ability of MBP to inhibit infection with strain L2 was not affected by supplementation with complement or addition of an L2-specific neutralizing monoclonal antibody. Enzyme-linked immunosorbent assay and dot blot analyses showed MBP bound to the surface of the organism to exert inhibition, which appeared to block the attachment of radiolabeled organisms to HeLa cells. Immunoblotting and affinity chromatography indicated that MBP binds to the 40-kDa glycoprotein (the major outer membrane protein) on the outer surface of the chlamydial elementary body. Hapten inhibition assays with monosaccharides and defined oligosaccharides showed that the inhibitory effects of MBP were abrogated by mannose or high-mannose type oligomannose-oligosaccharide. The latter carbohydrate is the ligand of the 40-kDa glycoprotein of C. trachomatis L2, which is known to mediate attachment, suggesting that the MBP binds to high mannose moieties on the surface of chlamydial organisms. These results suggest that MBP plays a role in first-line host defense against chlamydial infection in humans.  相似文献   
998.
Free‐radical copolymerization is used to synthesize poly[styrene‐co‐(4‐vinylbenzyl azide)] (PS‐co‐PVBN3), followed by click chemistry to react it with propargyl thymine (PT) to obtain a series of high‐performance polystyrene derivatives, poly[styrene‐co‐(4‐vinylbenzyltriazolylmethylmethylthymine)] (PS‐co‐PVBT). The presence of the thymine units on the side chains of the PS copolymers allows specific intermolecular association through self‐complementary T–T interactions. In addition, the thermal and dynamic rheological properties of PS‐co‐PVBT increase significantly when it is blended with melamine (M) because of the strong, complementary, multiple hydrogen‐bonding interactions that occur between the T units and this low‐molecular‐weight compound (M).  相似文献   
999.
外科医生和手术室人员经常接触手术设备产生的烟气,病人也会暴露于烟气中,特别是腹腔镜手术中产生的烟气滞留于腹腔内这一密闭空间并被吸收.这些烟气是一种与香烟烟气相似的毒性物质,然而对这种毒性物质的影响还未引起足够重视.应该采取必要措施尽可能减少手术中烟气的不良影响.  相似文献   
1000.
Tardive gait     
Tardive dyskinesia (TD) is a hyperkinetic movement disorder induced by dopamine receptor blocking drugs (DRBDs). TD typically presents with stereotypy or dystonia, but may also cause akathisia, myoclonus, or tremor. However, no detailed reports of gait abnormalities have been documented. We report three patients exposed to DRBDs who developed "tardive gait" and conclude that gait dysfunction may be part of the TD spectrum.  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