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   8424篇
  免费   506篇
  国内免费   39篇
耳鼻咽喉   186篇
儿科学   187篇
妇产科学   128篇
基础医学   997篇
口腔科学   711篇
临床医学   681篇
内科学   2065篇
皮肤病学   170篇
神经病学   710篇
特种医学   177篇
外科学   1319篇
综合类   60篇
一般理论   1篇
预防医学   539篇
眼科学   189篇
药学   498篇
中国医学   21篇
肿瘤学   330篇
  2024年   5篇
  2023年   92篇
  2022年   185篇
  2021年   389篇
  2020年   211篇
  2019年   369篇
  2018年   383篇
  2017年   256篇
  2016年   290篇
  2015年   313篇
  2014年   450篇
  2013年   471篇
  2012年   781篇
  2011年   787篇
  2010年   413篇
  2009年   344篇
  2008年   495篇
  2007年   491篇
  2006年   420篇
  2005年   378篇
  2004年   359篇
  2003年   265篇
  2002年   254篇
  2001年   82篇
  2000年   76篇
  1999年   65篇
  1998年   31篇
  1997年   34篇
  1996年   14篇
  1995年   19篇
  1994年   14篇
  1993年   19篇
  1992年   18篇
  1991年   26篇
  1990年   26篇
  1989年   23篇
  1988年   15篇
  1987年   18篇
  1986年   18篇
  1985年   10篇
  1984年   8篇
  1983年   5篇
  1982年   8篇
  1981年   4篇
  1979年   8篇
  1977年   2篇
  1976年   4篇
  1975年   5篇
  1974年   2篇
  1970年   2篇
排序方式: 共有8969条查询结果,搜索用时 0 毫秒
991.
The new age of Precision Cancer Medicine, with specific biomarkers being used to direct targeted agents, generally concerns only a subset of patients within a certain histopathologically defined tumor type. This paradigm is challenged by the need to perform widespread molecular screening in certified laboratories, with results available to clinicians within reasonable timeframe. Tumor heterogeneity and clonal evolution must be considered in the decision making process. Adaptive and innovative clinical trial designs exploring predictive algorithms and reconsideration of traditional efficacy endpoints are required to rapidly translate scientific discoveries into patient care. Furthermore, international collaboration in cancer research and open discussions on the availability of investigational agents will likely redefine the drug development and approval process in the coming years.  相似文献   
992.
This study evaluated the lymphatic density and HIF-1α immunoexpression in lower lip squamous cell carcinoma (LLSCC) and their correlation with clinicopathological (nodal metastasis, clinical stage, histological grade, recurrence and disease outcome) and survival parameters in 20 metastatic and 20 non-metastatic LLSCCs. Lymphatic density was established by counting microvessels (D2-40+) at the tumor core (intratumoral lymphatic density, ILD) and at the invasive front (peritumoral lymphatic density, PLD) and percentages of immunopositive cells for HIF-1α were established. No statistically significant differences in lymphatic densities in relation to clinicopathological parameters were observed (P > 0.05). All cases exhibited nuclear and cytoplasmic HIF-1α immunoexpression, with relatively high percentages of positivity, but this expression was not statistically different in relation to clinicopathological variables (P > 0.05). Positive correlations were observed between ILD and PLD (P = 0.002), and between nuclear HIF-1α immunoexpression at the tumor core and ILD (P = 0.001). The results suggest ILD and PLD are not directly related to the development of lymph node metastasis in LLSCC. The striking expression of HIF-1α suggests the involvement of this protein in the etiopathogenesis of LLSCCs, possibly stimulating lymphangiogenesis at the tumor core. However, this protein does not seem to exert a determining influence on the biological aggressiveness of these tumors.  相似文献   
993.
994.

Purpose

This retrospective chart review study assessed patient records to determine implant insertion torque (IT) and implant stability quotient (ISQ) values during implant placement to evaluate the correlation with cortical bone anchorage (mono- or bicortical).

Methods

Primary stability data (IT during implant placement surgery and ISQ values immediately after implant placement) and cone beam computed tomography of 33 patients (165 implants) were assessed. Patients were divided into the following groups: G1, implants with apical cortical bone contact; G2, implants with bicortical bone contact (apical and cervical regions); and G3, implants with cervical cortical bone contact.

Results

Sixty-eight implants were excluded due to cortical bone contact on regions other than implant apical or cervical. Ninety-seven implants were therefore assessed for this study. No implant failure was found after a mean 70.42-month follow-up time. Implants with bicortical anchorage (G2) showed higher IT (64.1 Ncm) during implant placement and higher ISQ values (76) (p?<?0.05). Monocortical implants (G1, apical, and G3, cervical) showed similar IT (G1 52.3 and G3 54.3) and ISQ values (G1 71.9 and G3 73) (p?>?0.05). No correlation (Pearson correlation coefficient) was found between the two stability measurement devices for the different cortical bone anchorages that were analyzed (G1 0.190, G2 0.039, and G3 ??0.027) (p?>?0.05).

Conclusions

Insertion torque values and implant stability quotients were influenced by cortical bone contact. No significant correlation was found between IT and ISQ values—higher insertion torque values do not necessarily lead to higher implant stability quotients.
  相似文献   
995.
The majority of commensal oral streptococci are able to generate hydrogen peroxide (H2O2) during aerobic growth, which can diffuse through the cell membrane and inhibit competing species in close proximity. Competing H2O2 production is mainly dependent upon the pyruvate oxidase SpxB, and to a lesser extent the lactate oxidase LctO, both of which are important for energy generation in aerobic environments. Several studies point to a broad impact of H2O2 production in the oral environment, including a potential role in biofilm homeostasis, signaling, and interspecies interactions. Here, we summarize the current research regarding oral streptococcal H2O2 generation, resistance mechanisms, and the ecological impact of H2O2 production. We also discuss the potential therapeutic utility of H2O2 for the prevention/treatment of dysbiotic diseases as well as its potential role as a biomarker of oral health.  相似文献   
996.
The development of supported catalysts based on simple procedures without waste products and time-consuming steps is highly desirable. In this paper, self-supported nickel-based nanoparticles were obtained at the surface of the germanophosphate glasses by bottom-up process and evaluated as potential catalysts for the benzyl alcohol oxidation and bis(indolyl)methanes synthesis. A classical melt-quenching technique was used for preparing the nickel-doped germanophosphate glasses, followed by annealing under a hydrogen atmosphere at 400 °C for two different times. The approach enabled the synthesis of self-supported nanoparticles as a homogeneous film, covering the glass surface. The physical and chemical properties of synthesized glasses were characterized by UV-vis and Raman spectroscopies and thermal analysis. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were performed to monitor the growth process, morphology and chemical bonding structure of the nanoparticles surface.

The development of supported catalysts based on simple procedures without waste products and time-consuming steps is highly desirable.  相似文献   
997.
Rectus femoris injuries are extremely common in athletes, particularly in soccer players, rugby player, and sprinters. Magnetic resonance imaging (MRI) plays a key role in diagnosis, prognosis, and rehabilitation of these injuries. The current article discusses current concepts in the diagnosis and treatment of rectus femoris injuries in elite athletes, including a discussion of the less well known myofascial injuries and key prognostic factors as seen at MR imaging.  相似文献   
998.
The current study addressed the role of visual information in the control of locomotion in people with Parkinson's disease. Twelve healthy individuals and 12 mild to moderate Parkinson's disease patients were examined while walking at self-selected velocities, under three visual sampling conditions: dynamic (normal lighting), static (static visual samples) and voluntary visual sampling. Subjects wore liquid crystal glasses for visual manipulation. Outcome measures included spatial-temporal parameters, braking and propulsive impulses, number of samples and total duration of voluntary visual samples. Interaction between groups and visual conditions was not observed for kinematic parameters or braking and propulsive impulses. There were no significant differences between groups for voluntary visual sampling variables. These findings suggest that the visual control of locomotion in Parkinson's disease patients was similar to that observed in controls. Furthermore, Parkinson's disease patients were not more dependent on visual information than healthy individuals for the locomotion control.  相似文献   
999.
In this article, we provide a concise review of the literature on nocturia and its interference with sleep and, consequently, on quality of life. There are few studies addressing the possible influences of nocturia on sleep disruption. Nocturia is a potential contributor to sleep disorders because affected individuals experience nonrestorative sleep due to frequent interruptions. We also attempted to determine whether individuals with nocturia wake to urinate or, alternately, urinate because they are awake. This review attempts to outline this specific association by examining the possible interactions with other medical conditions and the pathophysiology and prevalence. Most studies have observed a higher prevalence among women; however, the impact on quality of life is higher in men. Nocturia is not necessarily associated with natural aging. The exploration of these topics provides information to clarify the implications of nocturia on sleep, sleep disruption, and other related consequences. Additional evidence is still required to address the question of whether nocturia leads to disordered sleep or whether disordered sleep leads to nocturia.  相似文献   
1000.

Introduction and hypothesis

A process of added qualification of transvaginal mesh (TVM) placement is desirable.

Methods

Through a physician-led partnership of specialty societies, centers of excellence, and industry, a core curriculum encompassing mesh/graft biology, technical skills, and safety can be coupled with current educational endeavors instructing surgeons in the use of TVM. A posttest process can verify a knowledge-based competency in mesh/graft safety. An auditing process after implementation would be optimal.

Results

We recommend implementation of a five-step process in order to accomplish these goals.

Conclusions

It is hoped through these efforts, the ultimate goal of patient safety may be reached.
  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