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   8180篇
  免费   508篇
  国内免费   40篇
耳鼻咽喉   63篇
儿科学   132篇
妇产科学   108篇
基础医学   1079篇
口腔科学   233篇
临床医学   850篇
内科学   1625篇
皮肤病学   110篇
神经病学   952篇
特种医学   580篇
外科学   1463篇
综合类   31篇
一般理论   1篇
预防医学   247篇
眼科学   187篇
药学   462篇
中国医学   14篇
肿瘤学   591篇
  2024年   9篇
  2023年   89篇
  2022年   195篇
  2021年   399篇
  2020年   203篇
  2019年   248篇
  2018年   308篇
  2017年   230篇
  2016年   359篇
  2015年   380篇
  2014年   464篇
  2013年   492篇
  2012年   772篇
  2011年   703篇
  2010年   421篇
  2009年   366篇
  2008年   566篇
  2007年   497篇
  2006年   436篇
  2005年   412篇
  2004年   335篇
  2003年   318篇
  2002年   225篇
  2001年   33篇
  2000年   23篇
  1999年   34篇
  1998年   32篇
  1997年   27篇
  1996年   6篇
  1995年   17篇
  1994年   12篇
  1993年   7篇
  1992年   6篇
  1991年   10篇
  1990年   4篇
  1989年   9篇
  1988年   7篇
  1987年   6篇
  1986年   6篇
  1985年   5篇
  1984年   6篇
  1983年   6篇
  1981年   4篇
  1978年   3篇
  1977年   3篇
  1976年   5篇
  1975年   4篇
  1970年   4篇
  1969年   3篇
  1966年   4篇
排序方式: 共有8728条查询结果,搜索用时 15 毫秒
61.
ABSTRACT: BACKGROUND: Outcome measurement in shoulder surgery is essential to evaluate the patient safety and treatment efficiency. Currently this is jeopardized by the fact that most patient-reported selfassessment instruments are not comparable. Hence, the aim was to develop a reliable selfassessment questionnaire which allows an easy follow-up of patients. The questionnaire also allows the calculation of 3 well established scoring systems, i.e. the Shoulder Pain and Disability Index (SPADI), the Constant-Murley Score (CMS), and the Disabilities of the Arm, Shoulder and Hand (DASH) Score. The subjective and objective items of these three systems were condensed into a single 30-questions form and validated against the original questionnaires. METHODS: A representative collective of patients of our shoulder clinic was asked to fill in the newly designed self-assessment Munich Shoulder Questionnaire (MSQ). At the same time, the established questionnaires for self-assessment of CONSTANT, SPADI and DASH scores were handed out. The obtained results were compared by linear regression analysis. RESULTS: Fifty one patients completed all questionnaires. The correlation coefficients of the results were r = 0.91 for the SPADI, r = -0.93 for the DASH and r = 0.94 for the CMS scoring system, respectively. CONCLUSIONS: We developed an instrument which allows a quantitative self-assessment of shoulder function. It provides compatible data sets for the three most popular shoulder function scoring systems by one single, short 30-item. This instrument can be used by shoulder surgeons to effectively monitor the outcome, safety and quality of their treatment and also compare the results to published data in the literature.  相似文献   
62.
Because of the small particle size, orientation-dependent diffusion measurements in microporous materials remains a challenging task. We highlight here the potential of micro-imaging by interference microscopy in a case study with MFI-type crystals in which, although with different accuracies, transient concentration profiles in all three directions can be observed. The measurements, which were performed with “rounded-boat” shaped crystals, reproduce the evolution patterns of the guest profiles recorded in previous studies with the more common “coffin-shaped” MFI crystals. The uptake and release patterns through the four principal faces (which in the coffin-shaped crystals extend in the longitudinal direction) are essentially coincident and there is no perceptible mass transfer in the direction of the long axis. The surface resistances of the four crystal faces through which mass transfer occurs are relatively small and have only a minor effect on the mass transfer rate. As a result of the pore structure, diffusion in the crystallographic c direction (which corresponds to the direction of the long axis) is expected to be much slower than in the transverse directions. This could explain the very low rate of mass transfer observed in the direction of the long axis, but it is also possible that the small end faces of the crystal may have high surface resistance. It is not possible to distinguish unequivocally between these two possibilities. All guest molecules studied (methyl-butane, benzene and 4-methyl-2-pentyne) show the same orientation dependence of mass transfer. The long 4-methyl-2-pentyne molecules would be expected to propagate at very different rates through the straight and sinusoidal channels. The coinciding patterns for uptake through the mutually perpendicular crystal faces therefore provide clear evidence that both the coffin shaped crystals and the rounded-boat-shaped crystals considered in this study, must be intergrowths rather than pure single crystals.  相似文献   
63.
The coupling of a levitated submicron particle and an optical cavity field promises access to a unique parameter regime both for macroscopic quantum experiments and for high-precision force sensing. We report a demonstration of such controlled interactions by cavity cooling the center-of-mass motion of an optically trapped submicron particle. This paves the way for a light–matter interface that can enable room-temperature quantum experiments with mesoscopic mechanical systems.  相似文献   
64.
Inflammatory glomerular kidney diseases are often accompanied with a massive production of reactive oxygen species (ROS) that affect the function of the glomerular filtration barrier and contribute to mesangiolysis via the induction of cell death in mesangial cells. Intriguingly, ROS also trigger fine-tuned signalling processes that affect gene expression and cell proliferation or migration. To define such redox-driven signalling devices, a proteomics approach was performed to identify the formation of protein complexes induced by ROS. To this end, protein lysates of human podocytes were treated with or without hydrogen peroxide (250 μM). Thereafter cell lysates were subjected to diagonal 2D gel electrophoresis and putative redox-affected proteins were analysed by MS/MS analysis. Among others, the regulatory subunit of protein kinase A (PKA) could be identified that forms homodimers under oxidative conditions. To evaluate whether ROS dependent dimerization of PKA also occurs in a more physiological setting, rat mesangial cells were treated with platelet-derived growth factor-BB (PDGF-BB) to induce ROS formation. This regimen resulted in a redox dependent dimerization of the R-subunits of PKA. To demonstrate whether PDGF-BB induced ROS formation affects PKA dependent pathways, the effects of PDGF-BB on phosphorylation of serine 157 of vasodilator stimulated protein (VASP) a classical target of PKA were analysed. Interestingly PDGF-BB induced VASP phosphorylation in a ROS dependent manner but independent of changes in cAMP levels. Taken together, we demonstrate a redox-mediated activation of PKA by PDGF-BB thus highlighting a physiological role of ROS as regulator of PKA activity in rat mesangial cells.  相似文献   
65.
Inhalation of cigarette whole smoke (CWS) or its vapor phase (CVP) significantly impaired immune response capability in mice. Significant immunosuppressive effects on the humoral antibody response to a single antigenic stimulus were evident in animals exposed to smoke for seven days before or two days after administration of antigen. Impairment of the immunological response capability appeared to be temporary, with recovery about 14 days after exposure. Different lengths of exposure prior to antigenic stimulation neither produced an additive impairment of the immunological response nor rendered the experimental animals more tolerant to CWS or CVP. The immunological deficiency was specific to CWS and CVP inhalation rather than to nonspecific debilitating stress factors. The inductive phase was the period of the primary and secondary immune response most sensitive to impairment by exposure to CWS or CVP.  相似文献   
66.
67.
The vast majority of new HIV infections are acquired via the genital and rectal mucosa. Here, we provide an overview of our current knowledge of how HIV establishes local infection, with an emphasis on viral invasion through the female genital tract. Studies using human explant tissues and in vivo animal studies have improved our understanding of the cellular and molecular pathways of infection; this information could be harnessed to design effective HIV vaccines and microbicides.  相似文献   
68.
69.
To compare human immunodeficiency virus (HIV) type 1 disease progression in patients infected by the predominant strain circulating recombinant form (CRF) 02_AG in western and west-central Africa and in patients infected by other strains, a prospective multicenter cohort study was conducted in Cameroon and Senegal. Among the 335 patients, a broad HIV-1 group M subtype diversity was observed in the envelope V3-V5 region, but strain CRF02_AG predominated in both Cameroon and Senegal (61.2% and 62.9%, respectively; P<.8). Multivariate analyses showed no difference between patients infected by CRF02 strains and those infected by other strains in terms of survival (adjusted hazards ratio [HR], 1.16; 95% confidence interval [CI], 0.76-1.78; P=.5), clinical disease progression (HR, 0.79; 95% CI, 0.50-1.25; P=.3), or square root CD4 cell decline (regression coefficient, -0.01; 95% CI, -0.82 to 0.81; P=.9). This study suggests that the predominance of HIV-1 CRF02_AG strain in western and west-central Africa should have no major clinical consequences.  相似文献   
70.
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