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   17735篇
  免费   878篇
  国内免费   77篇
耳鼻咽喉   314篇
儿科学   455篇
妇产科学   496篇
基础医学   2474篇
口腔科学   1510篇
临床医学   1087篇
内科学   3766篇
皮肤病学   574篇
神经病学   1449篇
特种医学   614篇
外科学   2466篇
综合类   66篇
一般理论   3篇
预防医学   1241篇
眼科学   332篇
药学   1010篇
中国医学   111篇
肿瘤学   722篇
  2023年   134篇
  2022年   380篇
  2021年   603篇
  2020年   414篇
  2019年   500篇
  2018年   614篇
  2017年   404篇
  2016年   437篇
  2015年   553篇
  2014年   774篇
  2013年   903篇
  2012年   1383篇
  2011年   1509篇
  2010年   853篇
  2009年   731篇
  2008年   1219篇
  2007年   1190篇
  2006年   1106篇
  2005年   1068篇
  2004年   833篇
  2003年   731篇
  2002年   649篇
  2001年   128篇
  2000年   105篇
  1999年   120篇
  1998年   128篇
  1997年   138篇
  1996年   104篇
  1995年   105篇
  1994年   86篇
  1993年   81篇
  1992年   55篇
  1991年   56篇
  1990年   41篇
  1989年   36篇
  1988年   54篇
  1987年   35篇
  1986年   44篇
  1985年   43篇
  1984年   41篇
  1983年   39篇
  1982年   30篇
  1981年   26篇
  1980年   17篇
  1978年   13篇
  1977年   20篇
  1976年   18篇
  1975年   14篇
  1974年   13篇
  1968年   15篇
排序方式: 共有10000条查询结果,搜索用时 22 毫秒
121.
Observations made in an investigation of the diurnal variation of the serum iron concentration suggested that the diurnal variations of serum iron can be explained as a phenomenon secondary to the diurnal variation of the hemoglobin metabolism. This hypothesis is supported by parallel changes in the bilirubin and serum iron values.  相似文献   
122.
123.
ABSTRACT

Through qualitative data collected with women affected by drug use and drug-related violence in Bogotá, this article explores the convergence of harm reduction rationales and violence prevention programming in the urban margins to advocate for women’s health empowerment and health rights as victims of intergenerational trauma and violence. We propose a methodological shift of public health praxis from street-based outreach models to intimate spaces of intervention for health outcomes embodiment 1 1 Drawing from Krieger’s (2004) conceptualisation, we define embodiment as the stories our bodies hold and how they interact with the urban environment. as we continue to develop our community health model to work with marginalised communities in the urban global South. Through this work committed to social justice in marginalised urban communities, we seek to support women’s health needs through harm reduction in historically marginalised communities in urban settings. Our results expose how multi-level gender-based violence affects women’s health in their living spaces in the urban margins. Drawing from women’s voices and narratives of urban violence, we call for a feminist alternative to traditionally masculinist and public-space oriented harm reduction practice for health empowerment in the urban margins.  相似文献   
124.
Introduction  Patients undergoing major hepatectomy are at increased risk for post-operative morbidity and mortality, and changes in the phenotype of effector cells may predispose these patients to infectious sequelae. Methods  To better understand post-hepatectomy immune responses, peripheral blood from 15 hepatectomy patients was drawn immediately before and after liver resection and on post-operative days 1, 3, and 5. Circulating monocytes and dendritic cells were analyzed by flow cytometry for quantity, phenotype, activation status, human leukocyte antigen DR (HLA-DR) expression, and toll-like receptor-2 and -4 expression. Results  Major hepatectomy increased the numbers of activated CD16bright blood monocytes and the percentage of activated dendritic cells, although monocyte HLA-DR expression was reduced. These results may represent both dysfunctional antigen presentation and pending anergy, as well as cellular priming of immune effector cells. Better understanding of the alterations in innate immunity induced by hepatectomy may identify strategies to reduce infectious outcomes.  相似文献   
125.
Several classification schemes have been developed for anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), with actual debate focusing on their clinical and prognostic performance. Sixty-two patients with renal biopsy-proven AAV from a single center in Mexico City diagnosed between 2004 and 2013 were analyzed and classified under clinical (granulomatosis with polyangiitis [GPA], microscopic polyangiitis [MPA], renal limited vasculitis [RLV]), serological (proteinase 3 anti-neutrophil cytoplasmic antibodies [PR3-ANCA], myeloperoxidase anti-neutrophil cytoplasmic antibodies [MPO-ANCA], ANCA negative), and histopathological (focal, crescenteric, mixed-type, sclerosing) categories. Clinical presentation parameters were compared at baseline between classification groups, and the predictive value of different classification categories for disease and renal remission, relapse, renal, and patient survival was analyzed. Serological classification predicted relapse rate (PR3-ANCA hazard ratio for relapse 2.93, 1.20–7.17, p?=?0.019). There were no differences in disease or renal remission, renal, or patient survival between clinical and serological categories. Histopathological classification predicted response to therapy, with a poorer renal remission rate for sclerosing group and those with less than 25 % normal glomeruli; in addition, it adequately delimited 24-month glomerular filtration rate (eGFR) evolution, but it did not predict renal nor patient survival. On multivariate models, renal replacement therapy (RRT) requirement (HR 8.07, CI 1.75–37.4, p?=?0.008) and proteinuria (HR 1.49, CI 1.03–2.14, p?=?0.034) at presentation predicted renal survival, while age (HR 1.10, CI 1.01–1.21, p?=?0.041) and infective events during the induction phase (HR 4.72, 1.01–22.1, p?=?0.049) negatively influenced patient survival. At present, ANCA-based serological classification may predict AAV relapses, but neither clinical nor serological categories predict renal or patient survival. Age, renal function and proteinuria at presentation, histopathology, and infectious complications constitute the main outcome predictors and should be considered for individualized management.  相似文献   
126.
The effects of troglitazone 400 or 600 mg/d on the glycemic control, very-low-density lipoprotein (VLDL), and high-density lipoprotein (HDL) subclass concentrations and plasminogen-activator inhibitor 1 (PAI-1) levels were assessed in patients with type 2 diabetes that had not been controlled with dietary treatment. This was a multicenter, open-label, parallel-groups study. It included a run-in 4-week diet period and a 24-week randomized treatment. Fifty one patients received 400 mg/d and 55 patients 600 mg. The mean HbA(1c) concentration at the end of the study was similar for both doses. Troglitazone, regardless of dose, significantly improved insulin sensitivity assessed by the homeostasis model (HOMA). PAI-1 levels were significantly decreased in both groups by 13%. Higher HDL cholesterol concentrations and lower triglycerides levels were observed at the end of treatment. Triglyceride contents were reduced only in the lighter VLDL1. The change in HDL cholesterol concentration resulted from a combination of increased HDL3 cholesterol and lower HDL2 cholesterol levels. No differences were found in the effects of both treatment groups on the evaluated parameters. Our data provide new information about the actions of the drug on the lipid profile. Troglitazone reduces triglyceride levels by lowering the triglycerides content of the VLDL1 particles and increases HDL cholesterol concentrations by increasing HDL3 cholesterol levels.  相似文献   
127.
Manzanet G  Vela A  Corell R  Morón R  Calderón R  Suelves C 《Chest》2005,127(6):2211-2221
BACKGROUND: A pleural drainage system must be capable of efficiently evacuating the air or fluids from the pleural cavity so that adequate lung reexpansion can take place. The air flow and negative pressure of the system will depend on the particular design of each model. This experimental study analyzes the specifications and performance of the pleural drainage systems currently on the market. METHODS: Thirteen models of pleural drainage systems connected to wall suction were examined. The models were classified into the following three groups: dry systems; wet systems; and single-chamber systems. We determined the ambient air flow and the negative pressure generated according to the suction level. The components of each model are also described. RESULTS: Under normal conditions, dry (except for the Sentinel Seal; Sherwood Medical; Tullamore, Ireland), wet, and single-chamber systems reach similar air flow rates (17 to 30, 24 to 27, and 22 to 28 L/min, respectively). With higher wall suction levels, wet systems increase the air flow (26 to 49 L/min) but the negative pressure becomes unstable because of the water loss phenomenon, dry systems increase the air flow (29 to 50 L/min) without modifying the regulator pressure, and single-chamber systems also raise the air flow (45 to 51 L/min) but increase the negative pressure. When there is an air leak, dry systems (except for the Sentinel Seal) lose less negative pressure than the other systems. CONCLUSIONS: The functioning of these systems can be optimized only by applying a suitable wall suction level adjusted to each case. Although the three types of systems are capable of evacuating adequate air flow rates, the negative pressure and the capacity to maintain it in the presence of an air leak are different in each system. Being fitted with valves and not water compartments makes the dry systems the safest and the ideal for use when the patient has to be moved.  相似文献   
128.
129.
Neuronal nicotinic acetylcholine (AcCho) receptors composed of alpha7-subunits (alpha7-AcChoRs) are involved in many physiological activities. Nevertheless, very little is known about their single-channel characteristics. By using outside-out patch-clamp recordings from Xenopus oocytes expressing wild-type (wt) alpha7-AcChoRs, we identified two classes of channel conductance: a low conductance (gamma(L)) of 72 pS and a high one (gamma(H)) of 87 pS, with mean open-times (tau(op)) of 0.6 ms. The same classes of conductances, but longer tau(op) (3 ms), were seen in experiments with chimeric alpha7 receptors in which the wtalpha7 extracellular C terminus was fused to the green fluorescent protein (wtalpha7-GFP AcChoRs). In contrast, channels with three different conductances were gated by AcCho in oocytes expressing alpha7 receptors carrying a Leu-to-Thr 248 mutation (mutalpha7) or oocytes expressing chimeric mutalpha7-GFP receptors. These conductance levels were significantly smaller, and their mean open-times were larger, than those of wtalpha7-AcChoRs. Interestingly, in the absence of AcCho, these oocytes showed single-channel openings of the same conductances, but shorter tau(op), than those activated by AcCho. Accordingly, human homomeric wtalpha7 receptors open channels of high conductance and brief lifetime, and fusion to GFP lengthens their lifetime. In contrast, mutalpha7 receptors open channels of lower conductance and longer lifetime than those gated by wtalpha7-AcChoRs, and these parameters are not greatly altered by fusing the mutalpha7 to GFP. All this evidence shows that GFP-tagging can alter importantly receptor kinetics, a fact that has to be taken into account whenever tagged proteins are used to study their function.  相似文献   
130.
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