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   214950篇
  免费   9819篇
  国内免费   628篇
耳鼻咽喉   3268篇
儿科学   5922篇
妇产科学   4861篇
基础医学   29361篇
口腔科学   7694篇
临床医学   14572篇
内科学   51643篇
皮肤病学   6323篇
神经病学   17947篇
特种医学   5148篇
外国民族医学   2篇
外科学   26437篇
综合类   1253篇
一般理论   70篇
预防医学   20430篇
眼科学   4468篇
药学   15205篇
中国医学   1074篇
肿瘤学   9719篇
  2023年   1314篇
  2022年   1877篇
  2021年   4865篇
  2020年   2591篇
  2019年   4723篇
  2018年   7112篇
  2017年   4336篇
  2016年   4342篇
  2015年   5197篇
  2014年   6430篇
  2013年   9274篇
  2012年   15833篇
  2011年   16851篇
  2010年   8432篇
  2009年   6473篇
  2008年   13408篇
  2007年   14089篇
  2006年   13436篇
  2005年   13183篇
  2004年   11963篇
  2003年   11080篇
  2002年   10332篇
  2001年   5918篇
  2000年   6944篇
  1999年   4899篇
  1998年   1084篇
  1997年   821篇
  1996年   711篇
  1995年   640篇
  1994年   517篇
  1993年   438篇
  1992年   1665篇
  1991年   1391篇
  1990年   1221篇
  1989年   1042篇
  1988年   896篇
  1987年   814篇
  1986年   833篇
  1985年   736篇
  1984年   574篇
  1983年   469篇
  1982年   339篇
  1979年   493篇
  1978年   348篇
  1974年   433篇
  1973年   421篇
  1972年   345篇
  1971年   386篇
  1970年   344篇
  1969年   373篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
We present 5 patients with cyanotic congenital heart disease in whom a pulmonary valvuloplasty was performed as palliative therapy. The patients symptoms were hypoxemic spells, very low oxygen saturation and no weight gain. The oxygenation improved and symptoms disappeared. We believe that in properly selected patients this technique represents a good therapeutic modality.  相似文献   
142.
To elucidate the possible role of vitamin E in the pathogenesis of Parkinson's disease (PD), we compared serum levels of alpha-tocopherol (vitamin E), measured by high-performance liquid chromatography, and the vitamin E/cholesterol ratio of 42 Parkinson's disease (PD) patients using their spouses as the control group. The serum levels of vitamin E did not differ significantly between the groups (13.84 +/- 0.56 micrograms/ml for PD and 14.80 +/- 0.57 micrograms/ml for controls), nor did the vitamin E/cholesterol ratio (0.64 +/- 0.03 for both groups). There was no influence of antiparkinsonian therapy on vitamin E or the vitamin E/cholesterol ratio. Serum levels of the vitamin E and vitamin E/cholesterol ratio did not correlate with age, age at onset, scores of the Unified Parkinson's Disease Rating Scale or the Hoehn and Yahr staging in the PD group. These results suggest that serum vitamin E concentrations do not play a role in the pathogenesis of PD.  相似文献   
143.
144.
This prospective study was carried out on thirty patients transfused with blood or blood products, by ten (33.3%) posttransfusion hepatitis was diagnosed; this is 15.75 cases per 1,000 U transfused. Four patients developed jaundice; six remained asymptomatic. In nine patients (90%) non-A, non-B hepatitis was diagnosed and one (10%) case was classified as hepatitis B. Two patients with non-A, non-B hepatitis developed chronic hepatitis, corroborated through percutaneous liver biopsy.  相似文献   
145.
The aetiology of porphyria cutanea tarda (PCT) has not been elucidated, but the possibility of an autoimmune mechanism has been proposed. We report a case of an unknown clinical combination of PCT with autoimmune hypothyroidism, alopecia universalis and vitiligo with thyroid and parietal cell circulating antibodies. This is highly suggestive of underlying autoimmune damage in this patient.  相似文献   
146.
To determine the therapeutic activity on regional myocardial function of nifedipine intravenous administration (0.16 mg/kg) during short term myocardial induced ischemia, we used 6 mongrel dogs anesthetized and intubated those who we have implanted 3 pairs of ultrasonic crystals in the subendocardial layer. Utilizing an open chest canine model we performed total 1 minute and partial 2 minutes 30 seconds alternative obstructions, controlled with electromagnetic flowmeters in the anterior descending (AD) and circumflex (Cx) coronary arteries before and after drug administration. During the 70-80% obstructions we have shown a significant improvement in segment shortening, reduced by ischemia, in the ischemic and peri-ischemic zone. The ischemic markers, per cent increment of end diastolic length (% IEDL) and per cent increment of end systolic length (% IESL), have shown significant improvement during partial obstructions in the ischemic and peri-ischemic zone. After total obstructions the improvement on regional myocardial function is less marked and limited to ischemic zone.  相似文献   
147.
Summary: We questioned 229 general practitioners (GPs), 288 women who had recently delivered babies in public hospitals, 26 public hospital doctors, and 33 midwives in South Brisbane. Shared antenatal care was undertaken by 84% of mothers, and recently provided by 88% GPs. Mothers valued having sufficient time with their antenatal clinician, continuity of care, and short waiting and travel times. They preferred a GP to provide antenatal care, and a hospital midwife to deliver them. GPs were interested in providing even more obstetric care - one third in providing intrapartum care - and in gaining continuing education in obstetrics. Hospital doctors and midwives were supportive of women choosing the personnel to deliver them, and of an increased GP and midwife role in public hospital obstetrics, but unenthusiastic about home deliveries. There is widespread support for an increased role for GPs in public obstetrics.  相似文献   
148.
149.
Quantitative receptor autoradiography was used to study possible alterations of the densities of multiple serotonin (5-HT) receptor subtypes and of serotonin transporter in the brain of 5-HT(2C) receptor knockout mice. The radioligands employed were [(3)H]citalopram, [(3)H]WAY100,635, [(3)H]8-OH-DPAT, [(3)H]GR125743, [(3)H]sumatriptan, [(3)H]MDL100,907, [(125)I](+/-)DOI, [(3)H]mesulergine, [(3)H]5-HT, [(3)H]GR113808, and [(3)H]5-CT. As expected, radioligands that label 5-HT(2C) receptors showed a complete absence of labeling in mutant mice choroid plexus and significantly reduced densities in other brain regions expressing 5-HT(2C) receptors. With the rest of the radioligands, no significant alterations in the densities of labeled sites were found in any brain region. In situ hybridization showed no changes in 5-HT(2A) receptor and serotonin transporter mRNA levels, whereas 5-HT(2C) receptor mRNA levels were reduced in certain brain regions. The present results indicate that the mouse serotonergic system does not exhibit compensatory up- or down-regulation of the majority of its components (serotonin transporter and most 5-HT receptor subtypes) in response to the absence of 5-HT(2C) receptors.  相似文献   
150.
Two pregnancies in a patient with a fixed-rate pacemaker are reported. The first pregnancy was uneventful. The second had no maternal complications either. A moderate tachysystolia was detected during the second period. The newborn was delivered with forceps applied under spinal anesthesia. Newborn infant evolution presented no hazards, but umbilical cord analysis revealed a severe acidosis, in spite of a normal scalp analysis 45 min earlier. Epidural anesthesia is recommended for such patients.  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