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   1404286篇
  免费   97735篇
  国内免费   2253篇
耳鼻咽喉   20440篇
儿科学   46542篇
妇产科学   40962篇
基础医学   205585篇
口腔科学   38866篇
临床医学   117930篇
内科学   273768篇
皮肤病学   29825篇
神经病学   111456篇
特种医学   56685篇
外国民族医学   390篇
外科学   218537篇
综合类   27387篇
现状与发展   1篇
一般理论   334篇
预防医学   99037篇
眼科学   32300篇
药学   106742篇
  1篇
中国医学   2799篇
肿瘤学   74687篇
  2018年   13995篇
  2016年   12552篇
  2015年   14392篇
  2014年   18951篇
  2013年   28489篇
  2012年   39895篇
  2011年   41883篇
  2010年   24787篇
  2009年   22979篇
  2008年   40873篇
  2007年   44386篇
  2006年   45021篇
  2005年   44512篇
  2004年   42736篇
  2003年   41779篇
  2002年   41155篇
  2001年   62409篇
  2000年   63860篇
  1999年   54365篇
  1998年   15390篇
  1997年   13772篇
  1996年   13784篇
  1995年   12945篇
  1994年   12317篇
  1993年   11408篇
  1992年   42649篇
  1991年   41975篇
  1990年   41491篇
  1989年   40178篇
  1988年   37346篇
  1987年   36597篇
  1986年   34899篇
  1985年   33293篇
  1984年   24824篇
  1983年   21527篇
  1982年   12871篇
  1981年   11377篇
  1979年   23618篇
  1978年   16591篇
  1977年   14358篇
  1976年   13511篇
  1975年   14994篇
  1974年   17504篇
  1973年   16835篇
  1972年   16071篇
  1971年   14946篇
  1970年   13857篇
  1969年   13336篇
  1968年   12581篇
  1967年   11030篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
Premalignant lesions of the penis include cutaneous horn, balanitis xerotica obliterans, and leukoplakia. The true incidence of progression of each of these to squamous-cell carcinoma is unknown. Bowenoid papulosis, erythroplasia of Queyrat, and Bowen's disease are histologically identical to in situ carcinoma. Although the first is consistently benign, the latter two regularly evolve into invasive cancer. Malignant scrotal lesions include squamous-cell carcinoma, liposarcoma, leiomyosarcoma, basal-cell carcinoma, extramammary Paget's disease, erythroplasia of Queyrat, malignant melanoma, and metastases. Hemangioma can be confused with carcinoma.  相似文献   
102.
103.
Background: The association between aluminium and dialysis encephalopathy and deterioration of the neurological state during desferrioxamine treatment of dialysis patients is well established. At present little is known about the speciation and the mechanisms underlying the element's neurotoxicity. Methods. Aluminium speciation was performed in cerebrospinal fluid samples of acutely aluminium-intoxicated dialysis patients using a recently developed high-performance liquid chromatographic/electro-thermal atomic absorption spectrometric hybrid method. Results: Baseline cerebrospinal fluid aluminium levels of samples taken shortly after the intoxication were low but elevated (5.0±2.0 &mgr;g/l, n=3) as compared to subjects with normal renal function (<1 &mgr;g/l). In contrast to the situation noted in serum and to the iron speciation in cerebrospinal fluid, aluminium was not bound to transferrin but appeared as two distinct compounds, the main fraction eluting at the elution volume of aluminium citrate/silicate. The second compound was not identified. Forty-four hours after desferrioxamine administration the cerebrospinal fluid aluminium levels had increased up to a concentration of 10.3±2.5 &mgr;g/l (n=3). This was accompanied by a change in the speciation profile with aluminium appearing at the elution volume of aluminoxamine. Conclusion: Our findings may contribute to a better understanding of the neurotoxic effects of aluminium and its desferrioxamine chelate in dialysis patients.  相似文献   
104.
105.
106.
Variations of the medial and inferior choanal limits may facilitate snoring. These are: 1) short vomer without crista choanalis vomeris and adaptational formations, 2) extremely concave posterior margin of the hard palate leading to disproportion between the muscular and aponeurotic part of m. tensor veli palatini and hence to a flabby soft palate especially during sleep, and 3) neonatal relation of the height and width of the choane resulting in a very large choanal region instead of relative reduction of choanal width compared to its increasing height. All these variations result in a flabby soft palate especially during sleep and may lead to formation of whirles of inspired air and snoring.  相似文献   
107.
Various forms of signal processing are used in modern ASP hearing aids. The present study investigated the relationship between sentence recognition ability and two types of signal processing used in commercially available hearing aids. Results indicated a significant improvement in sentence recognition ability employing an instrument with adaptive compression (variable release time) versus an instrument with an adaptive high-pass filter with short attack and release times. Data were obtained for a single-talker competing message at several message-to-competition ratios. The adaptive compression system may prove to be beneficial to hearing-impaired listeners in certain background noise environments.  相似文献   
108.
109.
110.
The degree of metabolic acidosis at birth has been calculated in cord artery and vein samples from 21 term fetuses with cord artery pH less than 7.20. The aim of the study was to compare base deficit values calculated from either Siggaard-Andersen alignment nomogram (BD blood) or the Acid-Base chart (BD extra cellular fluid, BDecf). BDblood was found to be consistently higher in the cord artery as compared with BDecf, 13.2 +/- 3.5 and 9.9 +/- 2.9 mmol/l (Mean +/- SD), respectively. A significant correlation was found between cord artery PCO2 and BDblood whereas BDecf appeared unaffected by PCO2. In cases with cord entanglement BDecf a-v differences were increased to 3.4 +/- 2.3 mmol/l as compared with the small a-v difference noted in acidotic cases without cord entanglement, 1.1 +/- 1.25 mmol/l. It is speculated that with acutely emerging, intermittent asphyxia due to cord compression, a cord artery and vein difference in metabolic acidosis may exist and where the vein captures the basal level and the artery the acute changes. It is concluded that BDecf in both cord artery and vein add valuable information on the mechanisms behind metabolic acidosis.  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