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   324篇
  免费   19篇
  国内免费   13篇
耳鼻咽喉   2篇
儿科学   11篇
妇产科学   5篇
基础医学   37篇
口腔科学   15篇
临床医学   22篇
内科学   72篇
皮肤病学   10篇
神经病学   5篇
特种医学   71篇
外科学   34篇
综合类   14篇
预防医学   4篇
眼科学   2篇
药学   16篇
中国医学   3篇
肿瘤学   33篇
  2023年   1篇
  2021年   3篇
  2020年   6篇
  2019年   5篇
  2018年   7篇
  2017年   6篇
  2016年   4篇
  2015年   10篇
  2014年   11篇
  2013年   13篇
  2012年   9篇
  2011年   6篇
  2010年   18篇
  2009年   18篇
  2008年   12篇
  2007年   14篇
  2006年   13篇
  2005年   4篇
  2004年   3篇
  2003年   3篇
  2002年   7篇
  2001年   7篇
  2000年   3篇
  1999年   6篇
  1998年   22篇
  1997年   16篇
  1996年   18篇
  1995年   11篇
  1994年   11篇
  1993年   9篇
  1992年   3篇
  1991年   4篇
  1990年   3篇
  1989年   11篇
  1988年   6篇
  1987年   7篇
  1986年   8篇
  1985年   9篇
  1984年   2篇
  1983年   2篇
  1982年   5篇
  1981年   3篇
  1980年   3篇
  1979年   2篇
  1978年   2篇
  1977年   3篇
  1976年   4篇
  1975年   3篇
排序方式: 共有356条查询结果,搜索用时 15 毫秒
141.
This study was conducted to determine if the resistive index (RI) could be used for the examination and follow-up of neonates with increased intracranial pressure. First, in a laboratory model with four mongrel dogs, RI was found to correlate linearly with cerebral perfusion pressure. Second, RI was studied in 57 healthy neonates and 285 neonates with abnormal clinical or head ultrasound findings. Average RI for healthy newborns was 75 +/- 10 and was inversely related to gestational age. RI in newborns with abnormal findings was uniformly elevated, but these values varied considerably and were not statistically different from normal values. Third, the RI was found to decrease significantly after patent ductus arteriosus ligation, tapping of subdural effusions, ventricular tapping (later cerebrospinal fluid shunting led to a further drop in RI), and ventriculoperitoneal shunting. Elevated RI indicates possible intra- or extracranial abnormality affecting cerebral blood flow. Doppler RI is valuable in following up neonates with abnormal or unstable conditions and in assessing the effectiveness of therapies to improve cerebral perfusion.  相似文献   
142.
Recurrent miscarriage: principles of management   总被引:11,自引:7,他引:4  
Recurrent miscarriage is a heterogeneous condition which has many possible underlying causes. Ideally, couples with the problem should be managed in a dedicated miscarriage clinic, with thorough investigations according to a protocol, with structured history and investigation sheets. Counselling is an important feature and may be provided by a specially trained counsellor, or specialized nurse appropriately trained in counselling. Counselling should include an explanation of the possible underlying causes of the condition, and of the prognosis of each of the conditions. There is no definite cause of miscarriage in approximately half of the patients. No treatment is needed in this group, apart from reassurance and tender loving care. Treatment of unproven value, for example progesterone support in early pregnancy, should not be offered. Treatment offered empirically or as part of a research project should have a sound scientific and statistical basis, and should include careful counselling with informed consent of the patient. There are many controversial issues in the management of recurrent miscarriage; consequently, there is a need for locally agreed guidelines for management. Women who conceive again should be offered regular monitoring, including serial ultrasonography in the first trimester of pregnancy. An active audit programme to review regularly the various outcome measures set against defined targets should be established in the clinic.   相似文献   
143.
Cell surface aminopeptidases N (APN) and A (APA) have been characterized on cultured human glomerular epithelial cells and a SV40-transformed cell line derived from them. APN had a wide substrate specificity whereas APA only attacked peptides with an acidic N terminal amino acid. Both enzymes also differed by their sensitivity to divalent cations and to aminopeptidase inhibitors. Phorbolmyristate acetate (PMA) stimulated APN but not APA expression after a lag time of 12 hours. An increase of twice the basal value was observed with 10 ng.ml-1 PMA. This effect was confirmed by immunofluorescence staining using a specific anti-APN monoclonal antibody. Both ecto- and total enzyme activities were stimulated by PMA. The effect of PMA was suppressed by H7, a PKC inhibitor, and cycloheximide, an inhibitor of protein synthesis. Thrombin (1 to 2.5 U.ml-1) and interferon (IFN)-gamma (100 U.ml-1) also stimulated APN activity, the latter after longer exposure of the cells. APA activity was increased by 8-bromo-cAMP and two cAMP-stimulating agents, forskolin and isobutylmethylxanthine (IBMX). A twofold increase above basal value was obtained with 100 microM forskolin after 72 hours of treatment. cAMP-stimulated APA activity was suppressed by cycloheximide. Dexamethasone also stimulated APA activity. The effects of forskolin and dexamethasone were additive. These results demonstrate that APN and APA in glomerular epithelial cells are under different regulations: mitogens and IFN-gamma for APN, cAMP and glucocorticoids for APA. This selective expression may imply possible functional consequences in glomerular diseases.  相似文献   
144.
145.
SUMMARY A case of Münchausen's syndrome with AIDS illustrates the need for a high index of caution when dealing with individuals whose histories are inconsistent and suspicious, particularly when they have moved area.  相似文献   
146.
陆志仁  TCChen  MFHolick 《药学学报》1992,27(5):369-374
利用正相半制备柱和反相分析柱的两步高效液相色谱法,在实验室规模制备了毫克是级维生素D3的三个重要异构体——维生素D3前体、光甾醇3和速甾醇3·维生素D3原体,7-去氢胆固醇的光照是在一个装有UVB荧光灯的光治疗室中进行。采用紫外分光光度法和高效液相色谱法对制得的三个异构体进行了定性定量分析。在这三个异构体检测极限下,除了维生素D3前体中有不超过0.25%的维生素D3杂质外,三个产品中均没有发现任何除它本身之外的其他异构体杂质。  相似文献   
147.
SUMMARY The serendipitous presentation of a rectoperineal fistula in a 34-year-old nulliparous woman is described. This surgically correctable cause of an anogenital discharge posed a risk (if unrecognised) of producing a rectovaginal fistula at the time of vaginal delivery.  相似文献   
148.
149.
150.
Regional wall motion (RWM) abnormalities are sensitive indicators of left ventricular (LV) dysfunction, but quantitation of RWM with gated radionuclide ventriculography (RVG) has been limited, particularly in the left anterior oblique (LAO) projection. Regional LV performance was studied in 18 patients undergoing LAO RVG immediately prior to contrast ventriculography (CVG). Wall motion was analyzed by semiautomated and visual methods using several coordinate systems. For semiautomated methods, RVG and CVG wall motion were closely related in the two 90 degrees polar sectors at the apex and posterior wall (r = .85) and in the five 45 degrees polar sectors from midseptum through posterior wall (r = .82). The basal sectors on RVG had weak relationship to CVG, due to adjacent vascular structures. Semiautomated and visual grades for polar sectors on both CVG and RVG were closely related (r = .88- .94). Measured regional wall motion on LAO RVG compared favorably with near-simultaneous CVG in nonoverlapping portions of the LV and allowed objective quantitation of regional LV performance.  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