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   2400139篇
  免费   174291篇
  国内免费   3598篇
耳鼻咽喉   32684篇
儿科学   77055篇
妇产科学   63904篇
基础医学   354370篇
口腔科学   67716篇
临床医学   215264篇
内科学   468819篇
皮肤病学   53065篇
神经病学   189272篇
特种医学   88983篇
外国民族医学   490篇
外科学   360191篇
综合类   47972篇
现状与发展   12篇
一般理论   860篇
预防医学   187907篇
眼科学   55145篇
药学   177922篇
  11篇
中国医学   4903篇
肿瘤学   131483篇
  2021年   20930篇
  2019年   21149篇
  2018年   29063篇
  2017年   21673篇
  2016年   24106篇
  2015年   27263篇
  2014年   38354篇
  2013年   56683篇
  2012年   78776篇
  2011年   83898篇
  2010年   49473篇
  2009年   46386篇
  2008年   77701篇
  2007年   82680篇
  2006年   83070篇
  2005年   80270篇
  2004年   76528篇
  2003年   73564篇
  2002年   71166篇
  2001年   109157篇
  2000年   111855篇
  1999年   93862篇
  1998年   27274篇
  1997年   23871篇
  1996年   24252篇
  1995年   22874篇
  1994年   21038篇
  1993年   19824篇
  1992年   72161篇
  1991年   70229篇
  1990年   68546篇
  1989年   65818篇
  1988年   60433篇
  1987年   59225篇
  1986年   55338篇
  1985年   53111篇
  1984年   39413篇
  1983年   33475篇
  1982年   19916篇
  1979年   35936篇
  1978年   25720篇
  1977年   21281篇
  1976年   20366篇
  1975年   21863篇
  1974年   26208篇
  1973年   24877篇
  1972年   23243篇
  1971年   22073篇
  1970年   20300篇
  1969年   19366篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
A case illustrating the potentially fatal complication of endogenous Gram Negative Aerobic Bacillus (GNAB) septicaemia secondary to nosocomial pneumonia is presented along with current theories as to its aetiology. The technique of selective decontamination of the digestive tract is designed and advocated to prevent such occurrences; oral and maxillofacial surgeons should be aware of this approach. It may be, however, that by using much simpler manoeuvres such as changes in policy regarding gastric stress ulcer prophylaxis, the already small risk of such an occurrence will be further reduced. Awareness of this condition will allow a higher index of suspicion when presented with catastrophic septic complications on the ITU and aid in more rational planning of antimicrobial therapy.  相似文献   
142.
The effect of localized hyperthermia on blood flow and cis-diamminedichloroplatinum(II) (CDDP) pharmacokinetics in 7,12-dimethylbenz[a]anthracene-induced mammary adenocarcinomas was studied. Blood flow was determined in rat tumors and normal tissue immediately and 1, 2, and 3 h after local hyperthermia treatment (43 degrees C, 1 h) as well as in unheated tumors of rats. The rate of blood flow in the tumor was increased 1.9 times at the end of treatment relative to control values and returned to the control values by 3 h after hyperthermia. Similarly, the rate of blood flow in the peripheral skin around the tumor immediately after hyperthermia was 2.2 times greater than that of unheated skin and returned to near normal values by 3 h after heating. Tumor-bearing rats received CDDP 1 h before, at the beginning of, at the end of, and 1 h after hyperthermia administration. The CDDP plasma concentration versus time profiles for rats did not vary statistically between treatment groups. Two h after CDDP administration, the mean tumor CDDP concentration of the rats which received drug at the beginning of hyperthermia was statistically greater (P less than 0.05) than tumor CDDP concentrations in rats which received drug at the end of heat treatment. The latter group was given CDDP when tumor blood flow was the greatest; however, mean tumor drug concentration was lowest of all the groups. The mean drug concentration in tumor tissues of rats which received drug 1 h after hyperthermia was comparable to rats which received drug at the beginning of hyperthermia. This suggests that drug delivery or uptake in tumors may be altered when local hyperthermia is administered concurrently or sequentially.  相似文献   
143.
An increase in the number of cases of tuberculosis, especially in children, has been observed recently. Post-vaccination conversion rate in babies immunised with BCG was assessed. Sensitization was detected as early as 4 weeks after BCG inoculation. Although 84.2% had physical evidence of BCG inoculation only 69.8% had developed detectable sensitization to the tubercle bacilli as shown by the Mantoux test.  相似文献   
144.
Exposure to cadmium via the diet is known to depend to a large extent on the intake of cereal grains, particularly the high-fibre fractions of wheat. Subjects with low iron status absorb more cadmium than those with better iron status. The purpose of the present study was to determine to what extent cadmium accumulation in human placenta is affected by the intake of grain fibre and maternal iron status during pregnancy. Thirty-nine pregnant women participated in the study. In each trimester the women were requested to complete a dietary history and to allow blood samples to be taken for haemoglobin, serum ferritin and serum thiocyanate determinations, the latter as a marker for smoking. At delivery the whole placenta was taken for the determination of the cadmium concentration. The 32 women who had serum thiocyanate levels less than 70 mumol/l, who had completed at least one dietary history and from whom a blood sample was obtained in the third trimester, were included in the final statistical analyses. In the group of women who consumed less than the median intake of grain fibre and had more than 15 micrograms ferritin/l serum in the third trimester, the placenta cadmium concentration was nearly half that in the placentae of women who had consumed more grain fibre or had lower iron status in late pregnancy.  相似文献   
145.
Nephrotoxic cysteine conjugates derived from a variety of halogenated alkenes are enzymatically activated via the beta-lyase pathway to yield reactive sulfur-containing metabolites which bind covalently to cellular macromolecules. Mitochondria contain beta-lyase enzymes and are primary targets for binding and toxicity. Previously, mitochondrial protein and/or DNA have been considered as molecular targets for cysteine conjugate metabolite binding. We now report that metabolites of nephrotoxic cysteine conjugates form covalent adducts with rat kidney mitochondrial phospholipids. Rat kidney mitochondria were incubated with the 35S-labeled conjugates S-(1,1,2,2-tetrafluoroethyl)-L-cysteine (TFEC), S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine (CTFC), S-(1,2-dichlorovinyl)-L-cysteine, and S-(1,2,3,4,4-pentachlorobutadienyl)-L-cysteine. Quantitation of metabolite binding to whole mitochondria and to mitochondrial protein and lipid fractions revealed that as much as 42% of the 35S-label associated with the mitochondria was found in the lipid fraction. Total lipids were also extracted from 35S-treated mitochondria and separated by thin-layer chromatography. 35S-Containing metabolites were found in the lipid fractions from mitochondria treated with each of the conjugates. Lipids from both [35S]CTFC- and [35S]-TFEC-treated mitochondria contained major 35S-labeled lipid adducts which had similar mobility by thin-layer chromatography. Fatty acid analysis, 19F and 31P NMR spectroscopy, and mass spectrometric analyses confirmed that the major TFEC and CTFC adducts are thioamides of phosphatidylethanolamine.  相似文献   
146.
LUMBOVERTEBRAL SYNDROME AFTER EXTRADURAL BLOOD PATCH   总被引:2,自引:1,他引:1  
We describe a patient who developed an immobilizing lumbovertebralsyndrome after an extradural blood patch and who was hospitalizedwith a. suspected extradural abscess. An infectious aetiologyof the persistent backache could be excluded and the patientrecovered with analgesics and physiotherapy. The probable aetiologyis discussed.  相似文献   
147.
148.
To date, only 10 cases of distal penile gangrene in patients with chronic renal failure have been reported. This rare condition is believed to result from progressive vascular calcification due to secondary hyperparathyroidism in patients with chronic renal failure. We report an additional case of distal penile gangrene in a 41-year-old man who presented with chronic renal disease and pulmonary tuberculosis. Since some authors have emphasized that aggressive surgical treatment in such cases has a significant mortality rate, we took a more conservative approach to treatment.  相似文献   
149.
150.
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