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   1262877篇
  免费   96539篇
  国内免费   1577篇
耳鼻咽喉   16318篇
儿科学   41017篇
妇产科学   34951篇
基础医学   189437篇
口腔科学   34735篇
临床医学   117885篇
内科学   247936篇
皮肤病学   27279篇
神经病学   101879篇
特种医学   46793篇
外国民族医学   265篇
外科学   178819篇
综合类   25752篇
现状与发展   3篇
一般理论   568篇
预防医学   104685篇
眼科学   28070篇
药学   92605篇
  6篇
中国医学   2022篇
肿瘤学   69968篇
  2018年   13541篇
  2017年   10399篇
  2016年   11326篇
  2015年   13089篇
  2014年   18016篇
  2013年   27499篇
  2012年   37596篇
  2011年   39995篇
  2010年   23066篇
  2009年   22262篇
  2008年   37787篇
  2007年   40405篇
  2006年   39999篇
  2005年   39130篇
  2004年   37568篇
  2003年   35982篇
  2002年   34897篇
  2001年   56053篇
  2000年   57058篇
  1999年   48121篇
  1998年   13397篇
  1997年   12233篇
  1996年   12644篇
  1995年   11915篇
  1994年   11109篇
  1993年   10407篇
  1992年   38214篇
  1991年   37684篇
  1990年   36462篇
  1989年   35281篇
  1988年   32709篇
  1987年   32045篇
  1986年   30542篇
  1985年   28817篇
  1984年   21956篇
  1983年   19209篇
  1982年   11376篇
  1981年   10324篇
  1979年   20956篇
  1978年   15399篇
  1977年   12797篇
  1976年   11853篇
  1975年   12821篇
  1974年   15597篇
  1973年   15374篇
  1972年   14523篇
  1971年   13561篇
  1970年   12793篇
  1969年   12068篇
  1968年   11238篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The purpose of these experiments was to determine the effect of ethanol dose and time of administration on cerebral blood flow (CBF) and cerebral oxygen consumption (CMRO2). CBF and CMRO2 were measured in Sprague-Dawley rats 30 and 90 minutes after intraperitoneal injections of ethanol. Blood alcohol concentrations ranged from 1 to 3 mg/ml and were equivalent at both time periods. Ethanol produced small but significant increases in CBF and CMRO2 with blood alcohol concentrations. The above changes were not time dependent and were similar between 30 and 90 minute testing periods. The dose dependent effects of ethanol on cerebral metabolism are consistent with in vitro studies suggesting a dose related effect of ethanol on neuronal metabolism. The time of application appears to have little effect on the cerebral metabolic effects of alcohol.  相似文献   
992.
Atomic absorption spectrometry and x-ray fluorescence have been used to determine the lead content of metatarsal and tibia bone samples. For a range of bone lead levels from 6.5 to 83 micrograms g-1 of ashed bone there is no evidence of a systematic difference between the two techniques of more than 1 microgram g-1. There is, however, some evidence that random differences between the two in vitro analyses applied to the same bone sample are larger than can be accounted for by known measurement uncertainties. Variations in bone composition could account for these differences. Because the x-ray fluorescence technique is applied in an identical way to in vivo analysis, it is concluded that the uncertainties in in vivo measurements are small.  相似文献   
993.
994.
995.
In newly diagnosed adult patients with epilepsy followed prospectively on monotherapy, carbamazepine and phenytoin were associated with a fall in plasma uric acid, but sodium valproate and phenobarbitone were associated with a rise in plasma uric acid. The mechanisms and significance of these findings are discussed.  相似文献   
996.
Mechanical properties of post and core systems   总被引:1,自引:0,他引:1  
  相似文献   
997.
998.
Of 299 patients who presented with superficial bladder cancer (Ta, T1), 60 were treated by intravesical chemotherapy (Epodyl, methotrexate or mitomycin C). The rate of tumour progression to muscle invasion or metastases was identical for each intravesical regime. There was no evidence that mitomycin C promoted tumour progression. Carcinoma in situ in non-tumour-bearing urothelium was the most significant predictive factor for progression to muscle invasion or metastases.  相似文献   
999.
Five studies were conducted to examine the degree of variability to be expected during the use of the non-imaging nuclear probe (BIOS Inc.) under a variety of clinical conditions. Comparison of the ejection fraction (EF) readings between the nuclear probe and a gamma camera showed good agreement, with the nuclear probe tending to underestimate lower, and overestimate higher camera EF values [mean (S.D.) difference, 0.84% (6.06)]. A comparison of two nuclear probes showed a small mean (S.D.) difference of EF readings of 0.063% (2.26). EF readings obtained in normal subjects 6 weeks apart were reproducible and differed by a mean (S.D.) of 0.23% (4.42). The administration of placebo to 10 normal subjects followed by sequential measurements for 4 h produced EF changes large enough to mimic a clinical effect, the largest hourly change observed being 5.4%, indicating the need for strict placebo control in interventional experiments. Data on four patients with heart failure showed small non-significant EF changes in the 1 h after placebo administration but a wide intra-subject range of ejection time and time to peak filling measurements. This highlights the problem of accurate, reproducible cursor placement in such patients. The nuclear probe is a portable, low cost instrument which produces accurate EF measurements when compared with the gamma camera.  相似文献   
1000.
Bilateral simultaneous Achilles tendon ruptures are rare, with only ten cases reported in the English literature. Our case is that of a 44-year-old woman, along with a review of the literature. Affected persons usually are on chronic steroid treatment and in the fifth to seventh decades of life. The patient may have concomitant systemic disease, and the injury occurs with relatively mild trauma. The goals of treatment are mainly preventative, i.e., cessation of steroids as soon as possible and protective bracing of the remaining intact Achilles tendon.  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