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   8228篇
  免费   368篇
  国内免费   25篇
耳鼻咽喉   157篇
儿科学   148篇
妇产科学   313篇
基础医学   1671篇
口腔科学   181篇
临床医学   604篇
内科学   1479篇
皮肤病学   157篇
神经病学   614篇
特种医学   387篇
外国民族医学   1篇
外科学   1526篇
综合类   131篇
一般理论   2篇
预防医学   241篇
眼科学   207篇
药学   381篇
中国医学   8篇
肿瘤学   413篇
  2022年   42篇
  2021年   101篇
  2020年   49篇
  2019年   98篇
  2018年   105篇
  2017年   102篇
  2016年   130篇
  2015年   156篇
  2014年   177篇
  2013年   246篇
  2012年   385篇
  2011年   415篇
  2010年   249篇
  2009年   244篇
  2008年   416篇
  2007年   410篇
  2006年   389篇
  2005年   442篇
  2004年   410篇
  2003年   399篇
  2002年   380篇
  2001年   184篇
  2000年   140篇
  1999年   141篇
  1998年   75篇
  1997年   78篇
  1996年   71篇
  1995年   57篇
  1994年   51篇
  1992年   51篇
  1991年   84篇
  1990年   63篇
  1989年   61篇
  1988年   74篇
  1987年   59篇
  1986年   59篇
  1985年   63篇
  1984年   51篇
  1982年   51篇
  1980年   41篇
  1979年   44篇
  1977年   42篇
  1976年   42篇
  1975年   53篇
  1974年   60篇
  1973年   57篇
  1972年   37篇
  1937年   38篇
  1931年   38篇
  1926年   38篇
排序方式: 共有8621条查询结果,搜索用时 15 毫秒
41.
Summary Cyto- and myeloarchitectonic investigation of the temporal operculum and the exposed superior temporal gyrus was combined with a connection study of the projection fibers of the pertinent areas in the rhesus monkey.A belt-like organization of the auditory region with a koniocortex core (corresponding to AI) surrounded by belt areas was revealed. This organization principally resembled that of the auditory region of the cat (Rose and Woolsey, 1949; Woolsey, 1961) and that of other sensory regions (Sanides, 1972; Sanides and Krishnamurti, 1967). The belt is composed of one prokoniocortex area (proA, corresponding to AII) in parinsular location and of a caudal (paAc), lateral (paAlt) and rostral (paAr) parakoniocortex area. The latter has a particular character. It was found to be the target of thalamic projections of the caudalmost portion of GMpc. In contrast to the other parakonio areas it does not receive associations of the koniocortex.The belt areas, including the prokoniocortex, are ipsilaterally and transcallosally interconnected as in the somatic sensory (Jones and Powell, 1969a, b; Pandya and Kuypers, 1969; Pandya and Vignolo, 1969) and visual regions (Myers, 1962; Kuypers et al., 1965; Karol and Pandya, 1971).The koniocortex core is formed by two areas, Kam and Kalt, corresponding to the architectonic organization hitherto only known in man. The medial area (Kam) has a large number of homotopical callosal projections except at its medial border (to proA). The lateral area receives less callosal fibers, particularly most of its lateral portion is devoid of terminations. Since the belt areas are rich in callosal projections the supratemporal plane shows a pattern of three stripes of callosal terminations with two intermittent stripes void of terminations.While the projections of the koniocortex into the belt areas terminate prevalently in layer IV, the parakoniocortex sends fibers only into layers I and II of the koniocortex. This corresponds to results in somatic sensory (Pandya and McKenna, unpublished observations) and visual regions (Kuypers et al., 1965; Sanides and Vitzthum, 1965b; Spatz, personal communication).In contrast to other sensory regions the auditory koniocortex receives its exceptionally dense, homotopic callosal connections in the whole outer stratum with emphasis on layer III, as opposed to layer IV in the somatic sensory region.  相似文献   
42.
Cerebral dynamics of N-isopropyl-(123I)p-iodoamphetamine   总被引:1,自引:0,他引:1  
Temporal changes in the distribution of N-isopropyl-(123I)p-iodoamphetamine (IMP) within the brain are measured with serial tomographic imaging. In the cerebellum there is a decrease in activity of 42% from the early [15-45 min postinjection (p.i.)] to the late (210-240 min p.i.) scan, while in the cortex the decrease is 18%, and in the basal ganglia there is no decrease within this time. In brain tumors there was no IMP uptake in the early as well as in the late scans, regardless of tumor type, perfusion rate, or blood-brain barrier dysfunction. In 11 of 43 patients with a cerebral infarction a real increase of 123I activity (mean +21%) was seen in the late images. This "filling in" phenomena might be useful in selecting patients for bypass surgery. In these patients the diaschisis cerebelli, seen in the early scans, disappeared in the late images. The regional distribution of IMP changes with time; spatial ratios might be blurred by temporal changes. High-flow areas such as visio-auditory centers can be delineated clearly after stimulation in fast early scans; in these areas the pharmacokinetics of 123I are different from other cortex regions. To get the full information from the IMP brain uptake, both spatial and temporal variation must be measured.  相似文献   
43.
The granulocyte phagocytosis test, Karnofsky index, and ASA standard were used in the context of 287 patients for general surgery, for the purpose of retrospective elucidation of the relationship between presurgical prognostication and postsurgical complications. Sensitivity, specificity, and "predictive values" were calculated. The highest information potential in terms of prognostication was recorded from objectively measurable granulocyte phagocytosis. Presurgical prognostication was found to be of clinical relevance only to surgical problem patients.  相似文献   
44.
BackgroundThe present article analyzes the association of the functional anterior cruciate ligament (ACL) status and the overall varus deformity and coronal tibiofemoral subluxation (CTFS) in varus OA of the knee.MethodsOne hundred consecutive knees with varus OA in 84 patients were prospectively included. Knees were divided into two groups, in accordance with the ACL status (functionally sufficient or insufficient). All included patients were potential candidates for unicompartmental knee arthroplasty with predominantly medial compartment OA. Knees with Kellgren/Lawrence ≥ grade 3 in the lateral compartment were excluded leaving 79 knees to be included in this study. Mechanical varus deformity and CTFS were evaluated on AP radiographs and valgus stress radiographs, and compared between the two groups.ResultsKnees with a functionally insufficient ACL had significantly more varus deformity on hip-to-ankle AP standing radiographs (P = .001) and on valgus stress radiographs (P = .017). CTFS on AP standing radiographs was significantly higher (P = .045) in knees with a functionally insufficient ACL. Seventy-three percent (8/11) of the ACL-insufficient knees had a varus deformity of ≥10° and 64% (7/11) of ACL-insufficient knees had CTFS ≥ 6mm. By contrast, only one patient (2%, 1/41) with an insufficient ACL had< 10° varus deformity and a CTFS of < 6mm.ConclusionFunctional ACL insufficiency in osteoarthritic varus knees is associated with greater varus deformity and more advanced CTFS. Seventy-three percent of ACL-insufficient knees had a varus deformity of ≥10° and 64% of ACL-insufficient knees a CTFS of ≥ 6mm. In the work-up for medial unicompartmental knee arthroplasty, functional ACL insufficiency is likely in knees with varus deformity of ≥10° and CTFS of ≥ 6mm.  相似文献   
45.
46.
47.
Zusammenfassung Während der sterilenAutolyse der weißen Hirnsubstanz bis zu 24 Tagen verändern sich die Lipoide nur geringfügig. Die erst vom 9. Tage an verstärkte Abnahme des Lipoid-P beruht auf der Spaltung von Lecithin und Plasmalogen und wird von einer entsprechenden Zunahme freier Fettsäuren (FFS), geringerer der Aldehyde begleitet. FFS sind in der frischen weißen Substanz nur in Spuren nachweisbar. Lysophosphatide treten—im Gegensatz zu anderen Organen—in papierchromatographisch nachweisbarer Menge nicht auf. Cholesterin und seine Ester bleiben unverändert. Kephaline, Inositphosphatide, Sphingomyelin, Cerebroside und Sulfatide verhalten sich chromatographisch weitgehend konstant. Die postmortale Autolyse hat bis mehrere Tage nach dem Tode keinen nennenswerten Einfluß auf die Lipoidzusammensetzung.Bei der Untersuchung von 20 verschiedenenErweichungsherden des Gehirns fand sich eine vom Alter der Herde nicht unbedingt abhängige Zunahme der FFS, Aldehyde, Triglyceride und Cholesterinester. Freie wie auch glycerid- und cholesteringebundene Fettsäuren und freie höhere Aldehyde stammen offensichtlich aus den strukturbildenden Lipoiden des Myelin. In verschiedenen Herden treten spurenweise Lysophosphatide auf.
Summary Lipides change slightly during sterile autolysis of human white matter up to the 24 th day. From the 9 th day on, there is a decrease of lipid-phosphorus caused by a breakdown of lecithin and plasmalogen accompanied by a comparable increase of free fatty acids (FFA) and aldehydes. In fresh white matter there are only traces of FFA. In the autolysing brain, contrary to several other autolysing organs, there are no lysophosphatides detectable by means of paper chromatography. Free and esterified cholesterol, cephalins, phosphoinositides, sphingomyelin, cerebrosides and sulfatides remain chromatographically constant during sterile autolysis. According to the above findings it can be concluded that postmortem autolysis up to several days duration has only neglectable effects on the lipid-composition of the white matter.After analysis of 20 different foci of anaemic softening of human brain we found an increase of FFA, aldehydes, triglycerides and of esterified cholesterol which is independent on the age of the lesion. FFA as well as those fatty acids which are bound to glycerol and cholesterol and free higher aldehydes derive from the myelin lipides. Also in contrast to autolysis there were traces of lysophosphatides found in several foci.


Herrn Prof. Dr.E. Letterer zum Geburtstag am 30. Juni 1966 gewidmet.

Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.  相似文献   
48.
The European Laryngological Society is proposing a classification of different laryngeal endoscopic cordectomies in order to ensure better definitions of postoperative results. We chose to keep the word “cordectomy” even for partial resections because it is the term most often used in the surgical literature. The classification comprises eight types of cordectomies: a subepithelial cordectomy (type I), which is resection of the epithelium; a subligamental cordectomy (type II), which is a resection of the epithelium, Reinke’s space and vocal ligament; transmuscular cordectomy (type III), which proceeds through the vocalis muscle; total cordectomy (type IV); extended cordectomy, which encompasses the contralateral vocal fold and the anterior commissure (type Va); extended cordectomy, which includes the arytenoid (type Vb); extended cordectomy, which encompasses the subglottis (type Vc); and extended cordectomy, which includes the ventricle (type Vd). Indications for performing those cordectomies may vary from surgeon to surgeon. The operations are classified according to the surgical approach used and the degree of resection in order to facilitate use of the classification in daily practice. Each surgical procedure ensures that a specimen is available for histopathological examination. Received: 29 December 1998 / Accepted: 2 July 1999  相似文献   
49.
Mitotic gene conversions, among other recombinagenic events,can play an important role in the multistep process of carcinogenesis.The ability of chemicals to induce such gene conversions caneasily be monitored in the Saccharomyces cerevisiae tester strainYHE2, a derivative of strain D7. For the detection of drug-inducedgene conversions, two mutations in the TRP5 locus are used,trp5–12 and trp5–27. Here we report on the characterizationof the stable allele trp5–27. Our analysis revealed tworelevant mutations in trp5–27: (a) a transition C to Tat position 121 after ATG that results in an amber stop codonand abolishes gene expression and (b) a transversion A to Tat position 1555 that creates an ochre stop codon. Simultaneousamber and ochre suppression with the suppressors SUP3 and SUP11,respectively, was capable of relieving the tryptophan-requiringphenotype of strains carrying the trp5–27 allele. Thesefindings have implications on the length of gene conversiontracts in conversion events between trp5–12 and trp5–27:conversion tracts can cover several kilobases, if the site ofthe mutation in trp5–12 lies outside of the positionsmutated in trp5–27. Conversely, the maximal length islimited to 1435 bp, if the mutation in trp5–12 is locatedbetween the positions mutated in trp5–27. 1To whom correspondence should be addressed  相似文献   
50.
The increased uptake of native serum albumin in tumors is well described. In previous approaches to use this distribution pattern for tumor therapy, albumin molecules were loaded with maximum quantities of antineoplastic drugs. To preserve the properties of native albumin and to avoid enhanced phagocytotic clearance, we used methotrexate (MTX)-albumin-conjugates with a molar loading ratio of 1:1. In this study we evaluated the effects of single injections of MTX-rat-serum albumin (MTX-RSA) containing 50, 20 and 10 mug MTX on 40 BDIX rats bearing O-342 ovarian carcinoma. Tumor volume post treatment and area-under-the-curve of tumor volumes over treatment were compared with an untreated group using the Mann-Whitney U-test. MTX-RSA treatment caused dose dependent effects and in the 50 mug MTX-dosage significant (P 0.01) growth delay. Additional distribution studies with indirectly radio-iodinated MTX-RSA confirmed the prominent tumor uptake of this compound. We conclude that MTX-albumin-conjugates created with optimized labeling techniques and loading ratios cause significant effects even with very low MTX-doses. Thus these compounds may contribute to enhance the efficacy of MTX-treatment.  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