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   1277009篇
  免费   92900篇
  国内免费   1989篇
耳鼻咽喉   18187篇
儿科学   42302篇
妇产科学   37831篇
基础医学   187033篇
口腔科学   35391篇
临床医学   108190篇
内科学   251579篇
皮肤病学   26501篇
神经病学   99184篇
特种医学   49995篇
外国民族医学   366篇
外科学   197699篇
综合类   26530篇
现状与发展   1篇
一般理论   300篇
预防医学   92629篇
眼科学   29067篇
药学   97802篇
  1篇
中国医学   2498篇
肿瘤学   68812篇
  2018年   11815篇
  2015年   11617篇
  2014年   16007篇
  2013年   24371篇
  2012年   33555篇
  2011年   35959篇
  2010年   21218篇
  2009年   20025篇
  2008年   34996篇
  2007年   37963篇
  2006年   38513篇
  2005年   37807篇
  2004年   36396篇
  2003年   35390篇
  2002年   34938篇
  2001年   58104篇
  2000年   59600篇
  1999年   50701篇
  1998年   14247篇
  1997年   12820篇
  1996年   13078篇
  1995年   12354篇
  1994年   11760篇
  1993年   10865篇
  1992年   40992篇
  1991年   40366篇
  1990年   39892篇
  1989年   38709篇
  1988年   36113篇
  1987年   35352篇
  1986年   33729篇
  1985年   32136篇
  1984年   23927篇
  1983年   20823篇
  1982年   12383篇
  1981年   10932篇
  1980年   10208篇
  1979年   22640篇
  1978年   15879篇
  1977年   13732篇
  1976年   12973篇
  1975年   14203篇
  1974年   16691篇
  1973年   16082篇
  1972年   15324篇
  1971年   14238篇
  1970年   13220篇
  1969年   12736篇
  1968年   11982篇
  1967年   10479篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
112.
The biodistribution of two recently developed tumour markers, trimethylated (CP(Me)3) and trimethoxylated (CP(OMe)3) carotenoporphyrin, was investigated by means of laser-induced fluorescence (LIF) after i.v. injection into 38 tumour-bearing (MS-2 fibrosarcoma) female Balb/c mice. At 3, 24, 48 or 96 h after administration, the carotenoporphyrin fluorescence was measured in tumoral and peritumoral tissue, as well as in the abdominal, thoracic and cranial cavities. The fluorescence was induced by a nitrogen laser-pumped dye laser, emitting light at 425 nm, and analysed by a polychromator equipped with an image-intensified CCD camera. The fluorescence was evaluated at 490, 655 and 720 nm: the second and third wavelengths represent the carotenoporphyrin (CP)-related peaks, whereas the first one is close to the peak of the tissue autofluorescence. The tumour and the liver were the two tissue types showing the strongest carotenoporphyrin-related fluorescence, whereas the cerebral cortex and muscle consistently exhibited weak substance-related fluorescence. In most tissue types, the fluorescence intensities decreased over time. A few exceptions were observed, notably the liver, in which the intensity remained remarkably constant over the time period investigated.  相似文献   
113.
114.
Abstract Perioscan requires a plaque sample to detect the presence of enzymes capable of degrading N-benzoyl-DL-arginine-2-naphthylamide (BANA) from relatively few anaerobic periodontal pathogens. Periocheck assays the presence of neutral proteases in crevicular fluid. The aim of this study was to compare these test kits with traditional clinical methods of detecting periodontal disease and to monitor the ability of the kits to reflect the response to initial therapy. 19 patients with moderately severe chronic periodontitis were seen before and after a course of oral hygiene and root instrumentation consisting of 4 appointments. Clinical measurements and test assays were collected at 5 diseased sites and 2 healthy sites in each subject. Complete data from 125 sites were available for statistical analysis. At baseline Periocheck had a sensitivity of 88% and a specificity of 61% whereas Perioscan had a sensitivity of 99% and a specificity of 55%, when related to the clinical diagnosis. A composite clinical assessment, based on improvement or deterioration of one whole unit change of the subjective clinical indices and 2mm changes or greater in probing depth or probing attachment level, revealed 75 sites which improved following treatment, whereas 45 sites did not change and 5 sites deteriorated. The probability that the tests agreed with the clinical outcome after treatment, was calculated as 50.4% for Periocheck and 52% for Perioscan. The diagnostic kits did not reliably reflect the clinical assessment of periodontal disease in the cross sectional study, or the outcome following treatment.  相似文献   
115.
116.
A general analysis of the clinical failures that were responsible for deaths attributable to anaesthesia over a 30-year period, 1956-1987, is presented. Four particular general failures in clinical management were responsible for 80% of anaesthetic-contributory deaths (ACD). These were in descending order of frequency: (i) failures in airway management, of which the majority were associated with the complications of endotracheal intubation (27% of ACD); (ii) failures in pulmonary ventilation management (20% of ACD); (iii) failures in blood volume control (19% of ACD); and (iv) failures in arrhythmia control (17% of ACD). Computation of these groups of causes by the decade reveals a distinct and progressive change in the aetiological pattern of these deaths with time. While the incidence of ACD over the period decreased 6-fold from 0.43 to 0.07/1,000 anaesthetics, that proportion due to failures in airway management, in general, and complications of intubation, in particular, has progressively increased. This has been accompanied by a reciprocal decrease in deaths due to circulatory factors. It is postulated that this change arises from the fact that the physical skills, manual dexterity and clinical judgement demanded by the former have not changed with time, whereas the latter depend on intellectual responses to information derived from ever-improving vital function monitoring.  相似文献   
117.
The results of the in vitro fertilisation programme at Tygerberg Hospital for the period April 1983 to January 1988 are presented. Of the 1117 laparoscopies performed, 825 patients reached the transfer stage. A live-birth rate of 9.3% was achieved. The pregnancy rate after transfer of 4 embryos was 25.9% compared with 15.4% after 2 embryos and 10.8% after 3 embryos (P = less than 0.0001). The multiple pregnancy rate was 2.8% in the group receiving 2 embryos and 11.7% and 10.4% in those receiving 3 and 4 embryos, respectively. Of the 77 successful pregnancies (90 babies), 1 baby died at 34 weeks' gestation as the result of abruptio placentae due to preeclampsia and 1 cot death occurred. The only congenital abnormality encountered was a cleft palate.  相似文献   
118.
Eleven patients with lunatomalacia were treated by excision of the lunate and instillation of liquid silicone. The silicone vulcanised and formed an in-situ molded prosthesis. The patients were reexamined after a mean of 7.1 years. Four patients were pain-free and two had pain only at work; three had not been improved by the operation and two had undergone arthrodesis. The patients with good results all belonged to group IV pre-operatively. Surprisingly, no patient showed any sign of silicone synovitis, although all the prostheses except one had either fractured or deformed. The reasons for this are discussed and the indications for the operation established.  相似文献   
119.
120.
Two types of contrast media are now used in clinical magnetic resonance imaging (MRI). Intravenous gadolinium-DTPA serves as a marker of blood-brain barrier disruption while intravenous magnetic iron oxide particles are of value in imaging the liver and spleen. The efficacy of MRI is improved with these agents but the examination is prolonged.  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