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   1306806篇
  免费   100670篇
  国内免费   4127篇
耳鼻咽喉   18630篇
儿科学   44746篇
妇产科学   35335篇
基础医学   185370篇
口腔科学   34108篇
临床医学   115047篇
内科学   262493篇
皮肤病学   28269篇
神经病学   101724篇
特种医学   52415篇
外国民族医学   672篇
外科学   199592篇
综合类   31799篇
现状与发展   7篇
一般理论   380篇
预防医学   97565篇
眼科学   28572篇
药学   97781篇
  29篇
中国医学   3995篇
肿瘤学   73074篇
  2019年   10015篇
  2018年   14060篇
  2017年   10858篇
  2016年   11806篇
  2015年   13651篇
  2014年   18727篇
  2013年   27623篇
  2012年   37910篇
  2011年   40312篇
  2010年   24241篇
  2009年   22931篇
  2008年   38084篇
  2007年   40772篇
  2006年   40969篇
  2005年   39873篇
  2004年   38678篇
  2003年   37544篇
  2002年   36779篇
  2001年   64785篇
  2000年   67231篇
  1999年   57099篇
  1998年   15544篇
  1997年   14239篇
  1996年   14515篇
  1995年   13742篇
  1994年   12989篇
  1993年   11971篇
  1992年   44746篇
  1991年   43654篇
  1990年   42372篇
  1989年   40255篇
  1988年   37011篇
  1987年   36352篇
  1986年   33720篇
  1985年   32340篇
  1984年   24176篇
  1983年   20288篇
  1982年   11733篇
  1981年   10700篇
  1979年   21371篇
  1978年   14828篇
  1977年   12537篇
  1976年   11702篇
  1975年   12638篇
  1974年   14673篇
  1973年   14128篇
  1972年   12951篇
  1971年   11733篇
  1970年   11052篇
  1969年   10028篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
Bernard–Soulier syndrome (BSS) is a rare autosomal recessively inherited bleeding disorder. Pregnancy in patients with BSS is characterized by ante‐, intra‐, or postpartum haemorrhage, which may be delayed and severe. There is no consensus in the management of BSS in pregnancy and so far only 16 pregnancies in nine patients have been described. We report a further three pregnancies in two women with the syndrome. We also outline our management of pregnant patients with BSS.  相似文献   
54.
Conclusion  Several quality-control measures take place before (patient and camera preparation) and during SPECT acquisition to achieve high-quality images. Not uncommonly, technologists and physicians are left with suboptimal images that have to be addressed to reach the “right answer” for patient diagnosis and hence management. In many cases patients may be reimaged, especially if the problem is detected early, but in other cases either the patient has left the nuclear laboratory or there is an inevitable problem that, even with reimaging, will not be resolved. In these situations the technologist and physician have to seek the available techniques to obtain the best images possible. These resources are discussed in this issue as an aid in quality control to obtain the best possible images.  相似文献   
55.
56.
57.
58.
Chronic exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been shown to lead to the development of hepatotoxicity and carcinogenicity in the liver of female rats. In this study, we investigated hepatic gene downregulation in response to acute and subchronic TCDD exposure. We identified 61 probes which exhibited a downregulation of twofold or greater following subchronic (13 weeks) exposure to TCDD. Comparative analysis of the hepatic expression of these 61 probes was conducted with rats subchronically exposed to PeCDF, PCB126, PCB153, and a mixture of PCB126 and PCB153. PCB153 produced little or no alteration in these probes, while the binary mixture mimicked most closely the downregulation observed with TCDD. To discern if the repression of genes within this probe set occur as a primary response to TCDD exposure, we analyzed the early responsiveness of 11 genes at 6, 24, and 72 h following a single exposure to TCDD. We observed early repression of the 11 genes within this early time course, indicating that the repression of this subset of genes occurs as a primary response to TCDD exposure and not as a secondary response to 13 weeks of subchronic treatment. In addition, the gender, species, and AhR dependence of these responses were also investigated. Gender- and species-dependent repression was observed within this subset of genes. Furthermore, utilizing AhR knockout mice, we were able to determine the AhR-dependent downregulation of seven of 11 genes. Together these results assist efforts to understand the multitude of effects imposed by TCDD and AhR ligands on gene expression.  相似文献   
59.
BACKGROUND: Radioiodine therapy (RIT) combined with glucocorticoids is an effective therapy for Graves' disease, but it is debatable whether glucocorticoids should be applied in patients without Graves' ophthalmopathy (GO). METHODS: The effect of 0.4 - 0.5 mg prednisone every second day over a period of 5 weeks after RIT was monitored over a follow-up period of at least 12 months after RIT. A questionnaire was sent to 186 consecutive patients without GO concerning eye symptoms after RIT. 148 patients (80 %) answered. If eye symptoms had occurred after RIT, additional clinical examination was carried out at our outpatient clinic. The primary endpoint was the absence or onset of GO within the first year after RIT. RESULTS: Within 12 months after RIT the examination confirmed GO in 5 out of 148 patients (3.4 %). In all cases the symptoms were transient. No adverse reaction to the use of prednisone after RIT was noted. CONCLUSIONS: The risk of new GO in the first year after RIT was low and the clinical course of GO was mild when RIT was combined with a low-dose glucocorticoid regimen. Preventive administration of glucocorticoids can therefore be recommended in patients with Graves' disease even without evident GO.  相似文献   
60.
The present study compared four different sites and conditions for the measurement of maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) in 38 spontaneous breathing tracheotomised patients. Of the patients, 28 had chronic obstructive pulmonary disease (COPD). The four different conditions were: 1) through a cuff inflated cannula (condition A); 2) through the mouth with a deflated cannula (condition B); 3) through the mouth with a phonetic uncuffed cannula (condition C); and 4) through the mouth after stoma closure (condition D). Five trials in each condition were performed using a standardised method. The measurement of both MIP and MEP differed significantly depending on the condition of measurement. MIP taken in condition A was significantly higher when compared with conditions B, C and D. MEP in condition A was significantly higher when compared with condition B and D. In condition A the highest frequency of the best measurement of MIP and MEP was observed at the fourth and fifth effort, respectively. The same results were obtained after the selection of only COPD patients. In conclusion, respiratory muscle assessment differs significantly depending on measurement condition. Measurement through inflated cannula tracheotomy yields higher values of both maximal inspiratory and maximal expiratory pressure.  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