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   19058篇
  免费   1094篇
  国内免费   34篇
耳鼻咽喉   141篇
儿科学   582篇
妇产科学   377篇
基础医学   3703篇
口腔科学   208篇
临床医学   1924篇
内科学   3846篇
皮肤病学   542篇
神经病学   1593篇
特种医学   654篇
外科学   2173篇
综合类   112篇
一般理论   4篇
预防医学   1427篇
眼科学   324篇
药学   1201篇
中国医学   45篇
肿瘤学   1330篇
  2023年   97篇
  2022年   107篇
  2021年   316篇
  2020年   197篇
  2019年   302篇
  2018年   499篇
  2017年   341篇
  2016年   409篇
  2015年   463篇
  2014年   557篇
  2013年   788篇
  2012年   1320篇
  2011年   1367篇
  2010年   675篇
  2009年   562篇
  2008年   1197篇
  2007年   1183篇
  2006年   1166篇
  2005年   1204篇
  2004年   1070篇
  2003年   1006篇
  2002年   918篇
  2001年   282篇
  2000年   234篇
  1999年   218篇
  1998年   100篇
  1997年   91篇
  1996年   78篇
  1995年   76篇
  1994年   72篇
  1993年   68篇
  1992年   109篇
  1991年   109篇
  1990年   118篇
  1989年   124篇
  1988年   108篇
  1987年   97篇
  1986年   90篇
  1985年   85篇
  1984年   79篇
  1983年   57篇
  1979年   79篇
  1978年   60篇
  1975年   58篇
  1974年   66篇
  1973年   65篇
  1933年   65篇
  1932年   66篇
  1931年   63篇
  1927年   64篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Polyethylene terephthalate (PET) tubes have several advantages over glass tubes: they are unbreakable, lighter and more easily disposed of. Despite a steady increase in their use and an expansion of the range of available tubes, few studies validating their use have been published in the literature. This paper describes the various studies that have been performed to compare VENOJECT glass, VENOSAFE PET and VENOSAFE PET/heparin tubes for the assay of a panel of analytes in routine clinical chemistry, immunochemistry, hormone and tumor marker analysis and trace metal determination. These studies demonstrate that VENOSAFE PET tubes are a suitable alternative to glass tubes.  相似文献   
22.
This final issue of the series "Emergency and intensive care therapy for hematooncological diseases" reviews cytopenias in intensive care patients who do not offer any oncological or haematological problems in their medical history. Anaemia is a very common problem in the intensive care setting. We highlight aetiological aspects of anaemia in critically ill patients and discuss therapeutical options like substitution of blood and application of erythropoietin, respectively. The second paragraph focuses on leukocytopenia and agranulocytosis, their causation and therapy and among other things the application of G-CSF (Granulocyte colony-stimulating factor). Last but not least, we deal with thrombocytopenia, especially heparin-induced thrombocytopenia.  相似文献   
23.
Gluteal and lower extremity hypoplasia with ipsilateral toe brachysyndactyly were noted in a 23-year-old woman similarly affected to the only previously reported case of the lower extremity counterpart of Poland sequence. Since no neurological deficit was found, and electromyographic and nerve conduction studies in the affected limb were normal, we propose a vascular origin which would involve the external iliac artery supply analogous to the subclavian artery supply disruption in the upper extremity Poland sequence.  相似文献   
24.
Summary A total of 16 patients with recurrent epithelial ovarian cancer were treated with sulofenur (LY 186641), a novel oral sulfonylurea. All subjects had received previous chemotherapy. Anaemia occurred in all 16 patients, 14 of whom required a blood transfusion, and 2/16 patients received methylene blue for breathlessness due to methaemaglobinaemia. Treatment was discontinued in 2/16 cases due to rising liver enzyme values, which reverted to normal on cessation of the drug. There was no nausea or alopecia. Only two minor responses were seen. Plasma drug levels were insufficient to result in antitumour activity as extrapolated from animal data. Further studies that attempt to increase the bioavailability and improve the therapeutic index are warranted.  相似文献   
25.
Physiological and anatomical characteristics of antennal lobe interneurons in female Spodoptera littoralis (Boisd.) were investigated using intracellular recording and staining techniques. Responses of local interneurons and projection neurons to female sex pheromone components, host plant odours, and behaviourally active oviposition deterrents were recorded. We found local interneurons and projection neurons that responded specifically to only one or two of the tested odours, but we also found less specific cells, and neurons that responded to most of the tested odourants. These findings show that there are not only specific olfactory pathways in female moths up to the protocerebral level, but also that integration can begin in the antennal lobe. No correlation was found between the degree of specificity of either local interneurons or projection neurons and their respective morphological characteristics. Specialized and unspecialized local interneurons arborized throughout the antennal lobe. Specialized and unspecialized projection neurons had uniglomerular arborizations in the antennal lobe and sent their axons to the calyces of the mushroom body, and to the lateral horn of the protocerebrum. One specific projection neuron had multiglomerular arborizations and projected only to the lateral horn of the protocerebrum. Projection neurons arborizing in the glomeruli closest to the entrance of the antennal nerve always responded to pheromone components. No other correlations were found between the arborization pattern of projection neurons in the antennal lobe or in the protocerebrum and their response characteristics. The sensitivity of local interneurons and projection neurons was in the same range as that of receptor neurons in olfactory sensilla on the antennae, suggesting a much lower convergence in the central nervous system in females than in the pheromone-processing pathway in males. © 1994 Wiley-Liss, Inc.  相似文献   
26.
27.
The proteome of most parasite species is currently unknown. Hairworms (Nematomorpha), 300 species distributed around the world, are parasitic in arthropods (mainly terrestrial species) when juveniles, but they are free-living in aquatic environments when adult. Most aspects of their systematics and biology are currently unknown. The aim of this paper was (i) to report a novel and reproducible protocol for the analysis of the proteome of hairworms using two-dimensional gel electrophoresis (2-DGE) and mass spectrometry (matrix laser desorption ionization-time of flight mass spectrometry (MALDI-TOF)) and (ii) to determine the level of proteomic divergence between two sympatric but taxonomically unrelated nematomorph species in the adult stage, Paragordius tricuspidatus Dufour (Nematomorpha, Gordiidae) and Spinochordodes tellinii Camerano (Nematomorpha, Gordiidae). In total, 689 protein spots were observed for P. tricuspidatus, 575 for S. tellinii. Only 36.2% spots were shared between the two species. Quantitative analysis of the proteins which are common to both parasite species reveals substantial differences in the pattern of protein expression. These results suggest a rapid evolutionary divergence between these two nematomorph families. Also, to test the value of our MALDI-TOF protocol, we used Actin-2 (Act-2), a protein highly conserved in the course of evolution. Peptide mass fingerprint (PMF) data obtained for Act-2 of P. tricuspidatus and S. tellinii suggest a very high homology with Act-2 of different worms species belonging to the Bilateria phylum (Annelida and Nematoda) and more specifically to Lumbricus terrestris (Annelida, Lumbricidae) and Caenorhabditis elegans (Nematoda, Rhabditidae). We discuss our results in relationship with current ideas concerning the use of proteomics in systematics.  相似文献   
28.
PURPOSE: Hypotension is the most frequent complication of spinal anesthesia in pregnant patients. This study was designed to identify patients at risk for postspinal hypotension based on preoperative vital signs before and after an orthostatic challenge. METHODS: Forty healthy women scheduled for elective Cesarean section were enrolled in this prospective trial. Blood pressure (BP) and heart rate (HR) were recorded with the patient in the lateral supine position and after standing up. After a bupivacaine spinal anesthetic, BP was obtained every two minutes for 30 min. Ephedrine treatment was administered based on the degree of hypotension observed. Hemodynamic parameters were correlated to ephedrine requirements (Spearman's rank order correlation). RESULTS: There was a significant correlation in baseline maternal HR and ephedrine requirements (P=0.005). The degree of orthostatic changes in mean arterial BP and HR did not correlate with postspinal hypotension. CONCLUSIONS: Baseline HR may be predictive of obstetric spinal hypotension. Higher baseline HR, possibly reflecting a higher sympathetic tone, may be a useful parameter to predict postspinal hypotension.  相似文献   
29.
30.
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