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   27581篇
  免费   1761篇
  国内免费   83篇
耳鼻咽喉   190篇
儿科学   863篇
妇产科学   672篇
基础医学   4092篇
口腔科学   470篇
临床医学   3877篇
内科学   5045篇
皮肤病学   475篇
神经病学   2788篇
特种医学   720篇
外科学   2457篇
综合类   211篇
一般理论   26篇
预防医学   3115篇
眼科学   471篇
药学   1973篇
  1篇
中国医学   62篇
肿瘤学   1917篇
  2023年   236篇
  2022年   434篇
  2021年   766篇
  2020年   508篇
  2019年   693篇
  2018年   825篇
  2017年   586篇
  2016年   640篇
  2015年   830篇
  2014年   989篇
  2013年   1536篇
  2012年   2140篇
  2011年   2295篇
  2010年   1181篇
  2009年   1108篇
  2008年   1854篇
  2007年   1932篇
  2006年   1880篇
  2005年   1741篇
  2004年   1644篇
  2003年   1502篇
  2002年   1309篇
  2001年   190篇
  2000年   163篇
  1999年   192篇
  1998年   238篇
  1997年   180篇
  1996年   169篇
  1995年   123篇
  1994年   129篇
  1993年   111篇
  1992年   97篇
  1991年   99篇
  1990年   88篇
  1989年   93篇
  1988年   56篇
  1987年   62篇
  1986年   58篇
  1985年   60篇
  1984年   77篇
  1983年   81篇
  1982年   82篇
  1981年   53篇
  1980年   57篇
  1979年   43篇
  1978年   32篇
  1977年   32篇
  1976年   31篇
  1975年   30篇
  1974年   28篇
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
91.
Systemic angioendotheliomatosis is a very rare malignant disease characterized by intravascular neoplastic proliferation of reticuloendothelial cells. According to the clinical features three different types of prognostic value can be distinguished: Exclusive skin involvement; Progressive skin lesions disseminating to internal organs; Aggressive and lethal type affecting primarily internal organs. Until now about 60 cases of systemic angioendotheliomatosis have been reported in the literature. Here we describe the first well-documented case with almost isolated lung involvement. The presentation of morphologic and clinical signs and differential-diagnostic considerations are followed by a critical review of the literature.  相似文献   
92.
Evaluating the clinical nurse specialist. A review   总被引:7,自引:0,他引:7  
This paper reviews evaluative studies on the role of clinical nurse specialists and aims to describe and categorise research according to the methods used. By using the structure, process and outcome framework a clear pattern of research development and evidence emerges. It appears that significant benefits accrue for patients from the contribution of nurse specialists, but more experimental studies with combined methods should now be applied to this area.  相似文献   
93.
Two hundred and eighty five patients presenting with profound bilateral sensorineural hearing loss from 1987 to 1989, were subjected to a detailed history, pure tone audiogram, aided audiogram, Brain Stem Evoked Response Audiometry, Electrocochleography, Cochlear Nerve Test, and Tomograms of the temporal bones. All the data collected was subsequently analysed.  相似文献   
94.
95.
It is not known whether patients with pulmonary arterial hypertension associated with portal hypertension (portopulmonary hypertension (PPHTN) have different disease characteristics from those of patients with other forms of pulmonary arterial hypertension. We performed a retrospective cohort study of patients with PPHTN and patients with pulmonary arterial hypertension that was idiopathic, familial, or associated with anorexigen use (IPAH) to determine whether hemodynamics or survival were different between these groups. We included consecutive patients who underwent initial pulmonary artery catheterization and vasodilator testing at our center between January 1997 and May 2001 and who were followed until January 2004. Patients with PPHTN (N = 13) had a higher cardiac index and lower pulmonary vascular resistance than patients with IPAH (N = 33) (P < or = 0.001). Right atrial pressure and pulmonary artery pressure were similar between the groups. Patients with PPHTN had a higher risk of death in multivariate analysis (hazard ratio: [HR] = 2.8, 95% CI 1.04-7.4; P = 0.04). These findings were not affected by adjustment for differences in laboratory values, hemodynamics, or therapy. In conclusion, patients with PPHTN have a higher risk of death than that of patients with IPAH, despite having a higher cardiac index and lower pulmonary vascular resistance. Future studies of the specific mechanisms of and therapy for pulmonary arterial hypertension should focus on the distinctions between the different forms of this disease.  相似文献   
96.
Budd–Chiari syndrome (BCS) is characterized by obstruction of the hepatic venous outflow tract. Therapeutic options for BCS are limited. We report a case of a 21-year-old woman with protein S and C deficiency with gross ascites. Treatment with transjugular intrahepatic portosystemic shunt (TIPS) was attempted, which revealed occluded hepatic veins, so transcaval TIPS was performed. No serious procedure-related complication occurred. After successful shunt creation, the patient's symptoms subsided and she was discharged and followed up for 6 months.  相似文献   
97.
98.
Semantic memory is described as the storage of knowledge, concepts, and information that is common and relatively consistent across individuals (e.g., memory of what is a cup). These memories are stored in multiple sensorimotor modalities and cognitive systems throughout the brain (e.g., how a cup is held and manipulated, the texture of a cup's surface, its shape, its function, that is related to beverages such as coffee, and so on). Our ability to engage in purposeful interactions with our environment is dependent on the ability to understand the meaning and significance of the objects and actions around us that are stored in semantic memory. Theories of the neural basis of the semantic memory of objects have produced sophisticated models that have incorporated to varying degrees the results of cognitive and neural investigations. The models are grouped into those that are (1) cognitive models, where the neural data are used to reveal dissociations in semantic memory after a brain lesion occurs; (2) models that incorporate both cognitive and neuroanatomical information; and (3) models that use cognitive, neuroanatomic, and neurophysiological data. This review highlights the advances and issues that have emerged from these models and points to future directions that provide opportunities to extend these models. The models of object memory generally describe how category and/or feature representations encode for object memory, and the semantic operations engaged in object processing. The incorporation of data derived from multiple modalities of investigation can lead to detailed neural specifications of semantic memory organization. The addition of neurophysiological data can potentially provide further elaboration of models to include semantic neural mechanisms. Future directions should incorporate available and newly developed techniques to better inform the neural underpinning of semantic memory models.  相似文献   
99.
The introduction of highly active antiretroviral therapy (HAART) has resulted in marked reductions in mortality and acquired immunodeficiency syndrome (AIDS) incidence across all risk groups; however, the proportionate decrease among injecting drug users (IDUs) has been less impressive. Much of the disparity in benefit to IDUs has been a consequence of decreased access to and receipt of potent antiretroviral combinations. Strategies to increase access to and utilization of HAART have included entry into drug treatment and abstinence. Unfortunately, as few as 15%–20% of active drug users in the United States, and in many other countries, are in drug treatment at any one time. We report a pilot project among out-of-drug treatment IDUs infected with human immunodeficiency virus (HIV); HIV therapy was successfully provided to active heroin injectors using the Community Health Care Van (CHCV) at sites of needle exchange. Subjects were willing to initiate, but were not receiving, recommended HIV therapy and were not interested in formal drug treatment. Antiretroviral therapy regimens were selected and linked to heroin injection timing. Weekly visits were scheduled by CHCV staff to assess adverse side effects and encourage adherence. Of the 13 participants, the mean baseline HIV-1 RNA level and CD4 lymphocyte count were 162,369 (log 5.21) copies per milliliter and 265 cells per milliliter, respectively. By 6 months, the proportion whose HIV-1 RNA was below the limits of detection (<400 copies/mL) was 85% (N=11); 77% (N=10) had nondetectable levels by 9 months. By 12 months, 54% (N=7) had a persistently nondetectable viral load, and the net increase in CD4 lymphocyte count was 150 cells per milliliter. As an additional and unintended benefit of this pilot project, 9 (69%) subjects chose to enter drug treatment after achieving a nondetectable viral load. Entry into drug treatment was associated with durability of viral suppression. This small pilot study suggests that health services based on needle exchange may enhance access to HAART among out-of-treatment HIV-infected IDUs. In addition, it demonstrates that this population can benefit from this therapy with the support of a nontraditional, community-based health intervention.  相似文献   
100.
A biomechanical study comparing simulated lytic vertebral metastases treated with laser-induced thermotherapy (LITT) and vertebroplasty versus vertebroplasty alone. To investigate the effect of tumor ablation using LITT prior to vertebroplasty on biomechanical stability and cement fill patterns in a standardized model of spinal metastatic disease. Vertebroplasty in the metastatic spine is aimed at reducing pain, but is associated with risk of cement extravasation in up to 10%. Six pairs of fresh-frozen cadaveric thoracolumbar spinal motion segments were tested in axial compression intact, with simulated metastases and following percutaneous vertebroplasty with or without LITT. Canal narrowing under load, pattern of cement fill, load to failure, and LITT temperature and pressure generation were collected. In all LITT specimens, cement filled the defect without extravasation. The canal extravasation rate was 33% in specimens treated without LITT. LITT and vertebroplasty yielded a trend toward improved posterior wall stability (P = 0.095) as compared to vertebroplasty alone. Moderate rises in temperature and minimal pressure generation was seen during LITT. In this model, elimination of tumor by LITT, facilitates cement fill, enhances biomechanical stability and reduces the risk of cement extravasation.  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