全文获取类型
收费全文 | 2902516篇 |
免费 | 233942篇 |
国内免费 | 5520篇 |
专业分类
耳鼻咽喉 | 42823篇 |
儿科学 | 88644篇 |
妇产科学 | 78690篇 |
基础医学 | 410335篇 |
口腔科学 | 84275篇 |
临床医学 | 263376篇 |
内科学 | 562533篇 |
皮肤病学 | 58972篇 |
神经病学 | 243796篇 |
特种医学 | 116185篇 |
外国民族医学 | 1042篇 |
外科学 | 441099篇 |
综合类 | 72730篇 |
现状与发展 | 3篇 |
一般理论 | 1179篇 |
预防医学 | 234688篇 |
眼科学 | 69660篇 |
药学 | 216623篇 |
4篇 | |
中国医学 | 5387篇 |
肿瘤学 | 149934篇 |
出版年
2018年 | 28814篇 |
2016年 | 24698篇 |
2015年 | 28034篇 |
2014年 | 40476篇 |
2013年 | 61809篇 |
2012年 | 83150篇 |
2011年 | 87621篇 |
2010年 | 51561篇 |
2009年 | 49293篇 |
2008年 | 83121篇 |
2007年 | 89006篇 |
2006年 | 89653篇 |
2005年 | 87495篇 |
2004年 | 84648篇 |
2003年 | 81737篇 |
2002年 | 80451篇 |
2001年 | 130132篇 |
2000年 | 134619篇 |
1999年 | 114032篇 |
1998年 | 33555篇 |
1997年 | 30627篇 |
1996年 | 30190篇 |
1995年 | 29186篇 |
1994年 | 27509篇 |
1993年 | 25621篇 |
1992年 | 93138篇 |
1991年 | 89891篇 |
1990年 | 87001篇 |
1989年 | 83786篇 |
1988年 | 78116篇 |
1987年 | 77124篇 |
1986年 | 72967篇 |
1985年 | 70028篇 |
1984年 | 53521篇 |
1983年 | 45786篇 |
1982年 | 28300篇 |
1981年 | 25306篇 |
1980年 | 23818篇 |
1979年 | 51363篇 |
1978年 | 36381篇 |
1977年 | 30654篇 |
1976年 | 28664篇 |
1975年 | 30404篇 |
1974年 | 37606篇 |
1973年 | 35922篇 |
1972年 | 33690篇 |
1971年 | 31111篇 |
1970年 | 29454篇 |
1969年 | 27679篇 |
1968年 | 25175篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
Summary The left recurrent laryngeal nerves from five horses with sub-clinical neuropathy were examined by light and electron microscopy in a study designed to examine accumulation of axonal organelles at paranodal and internodal locations. Transverse sections of the nerve showed scattered fibres with split myelin sheaths and axonal accumulation of organelles. On longitudinal sections these collections were seen to result from an axonal outpouching in which dense lamellar bodies and mitochondria had accumulated. These paranodal collections, which could be found on both sides of the node, were often associated with infoldings of the terminal loops of myelin and with occasional paranodal demyelination. The fact that many of the organelles in the outpouches were lysosomal in nature was confirmed by their positive staining for cathepsin D activity. Longitudinal sections demonstrated a number of axons which were swollen over a long distance and which contained focal accumulations of similar organelles. In places, however, there was a clear separation between these organelles and the cytoskeletal proteins. In each case these swollen axons were surrounded by Schwann cell nuclei and their processes, forming well-ordered onion bulbs. The possibility that these two types of changes, i.e. the paranodal accumulations and the axonal swellings could result from a disturbance in axonal transport in this distal axonopathy is discussed. 相似文献
962.
Trends in analgesic self-poisoning in West-Fife, 1971-1985 总被引:1,自引:0,他引:1
J J McMurray D B Northridge V A Abernethy A A Lawson 《The Quarterly journal of medicine》1987,65(246):835-843
All admissions for analgesic self-poisoning to a district poisons unit over a 15-year period have been reviewed. During this time overdose with analgesic drugs increased to represent almost half of all admissions for self-poisoning. The types of analgesics taken in overdose also changed significantly during the period of this review. Aspirin and Distalgesic poisoning declined in incidence and more cases of self-poisoning by paracetamol and non-steroidal anti-inflammatory agents were seen. The impact of these changes on the medical management and outcome of deliberate self-poisoning is analysed. The reasons behind the trends described in this paper are assessed and their implications for future prevention and treatment are discussed. 相似文献
963.
We review evidence suggesting that deaf speakers do not move their articulators toward the following open posture throughout closure and report results from a preliminary cinefluorographic study. Two prelingually deaf and two hearing speakers produced two different strings of alternating heterogeneous monosyllables as though speaking in time with a metronome (the so-called P-center task). Events traditionally associated with vowel production appeared evenly timed throughout the productions, and, in general, the deaf speakers performed similarly to the hearing speakers. We relate the results to Fowler's (1983) interpretation of the P-center phenomenon as an indicant of continuous vowel production. 相似文献
964.
Martin Heine Evgeni Ponimaskin Ulf Bickmeyer Diethelm W. Richter 《Pflügers Archiv : European journal of physiology》2002,443(3):418-426
The HvCNG channel from the moth Heliothis virescens is highly sensitive to cAMP concentrations ranging between 0.1 microM and 5 microM. This HvCNG channel was over-expressed in Spodoptera frugiperda (Sf.9) cells to measure endogenous cAMP levels. Hyperpolarization-activated inward currents were measured in the whole-cell patch-clamp configuration with pipettes filled with different cAMP concentrations to calibrate the system. Varying the cAMP concentration between 0 microM and 100 microM in the pipette, the half-maximal activation voltage ( V1/2) was shifted by +28.5+/-1.7 mV. The activation time constant (tau(a)) was used as a parameter for cAMP quantification because it was independent of the expression level of HvCNG channels. tau(a) changed from 1106+/-60 ms at 0 microM cAMP to 265+/-7 ms at a saturating concentration of 1 mM cAMP. A dose-response relationship yielded values of 0.6 microM for the half-maximal cAMP concentration and 1.5 for the Hill coefficient. Activation of endogenous adenylyl cyclases by 50 microM forskolin induced an elevation of the cAMP level by about 1.6+/-0.2 microM. Co-expressions of HvCNG channels in combination with the mouse 5-HT4a- or 5-HT1A- receptors and the corresponding Gs- or Gi-proteins were successful and allowed us to also verify receptor-induced changes of the cAMP level. Stimulation of m5-HT4a-receptors by 0.1 microM 5-HT induced an increase of cAMP of about 4.6+/-1.5 microM, whereas cAMP levels decreased from a control value of 1+/-0.2 microM to 0.41+/-0.1 microM after stimulation of the m5-HT1A-receptors. 相似文献
965.
Thomas J Birk Rodger D MacArthur Lynn M Lipton Sheldon D Levine 《The Journal of the Association of Nurses in AIDS Care》2002,13(6):20-24
The purpose of this study was to determine whether blood lipid and lipoprotein concentrations varied in 5 men with advanced HIV-1 infection after 12 months of aerobic exercise training. Prior to exercise, the mean baseline cholesterol and high-density lipoprotein cholesterol (HDL-C) serum concentration were each lower, and mean baseline triglyceride concentration was higher compared to a healthy population norm. Consistent exercise training for 12 months failed to significantly (p > .05) alter cholesterol or HDL-C. Triglyceride concentration was significantly (p < .05) elevated above baseline (63 mg/dL) regardless of exercise compliance. The results suggest that long-term exercise training cannot correct lipid profile abnormality, particularly hypertriglyceridemia, common to individuals with advanced HIV-1 infection. 相似文献
966.
967.
M Havel H Teufelsbauer P Kn?bl R Dalmatiner P Jaksch W Zw?lfer M Müller T Vukovich 《The Journal of thoracic and cardiovascular surgery》1991,101(6):968-972
To study the hemostyptic effect of aprotinin (Trasylol) in patients undergoing extracorporeal circulation for coronary artery bypass operations, we randomized 12 of 24 patients to receive aprotinin in high dosage (about 800 mg) during extracorporeal circulation. From the resulting two groups each, one patient was excluded from the study because of postoperative myocardial infarction (control group) and surgical hemorrhage (aprotinin group) leading to a second operation. Although heparin was used for anticoagulation in all 22 patients, all had a marked increase in plasma levels of thrombin-antithrombin III complexes during extracorporeal circulation, indicating an intravasal activation of coagulation. By monitoring the plasma levels of fibrin degradation products in patients without aprotinin therapy, we recorded a concomitant hyperfibrinolysis significantly less pronounced in patients receiving aprotinin (p less than 0.005). The mean total postoperative blood loss was lower in patients receiving aprotinin (620 ml) than in control patients (1000 ml; p less than 0.03). The results confirm previous reports of a hemostyptic effect of aprotinin in cardiac operations. This effect is probably due to a prevention of hyperfibrinolysis. 相似文献
968.
Familial expansile osteolysis: a morphological, histomorphometric and serological study. 总被引:1,自引:0,他引:1
Biopsies from the diseased bones of patients with familial expansile osteolysis (FEO) were examined by light and electron microscopy. Focal concentrations of multinuclear osteoclasts were present, and these contained viral-like microcylindrical inclusions which appeared exclusive to their nuclei. No consistent relationship was found between osteoclast size and the number of osteoclast nuclei containing microcylindrical inclusions. Quantitative histomorphometry showed evidence of increased bone remodelling with high bone cell densities and a decrease of the reversal period in bone remodelling. The lesions contained prominent woven bone and fibrovascular tissue, together with mononuclear cells and adipocytes. Little bone was found in the most radiolucent lesions, which were almost totally occupied by adipocytes and fibrovascular tissue. Serology did not reveal any significant differences between the viral antibody titres of patients and their age- and sex-matched controls. The present study suggests that intranuclear viral-like microcylindrical inclusions of osteoclasts are not a specific feature of Paget's disease, and are found in other disorders of osteoclast function, including pycnodysostosis, osteopetrosis, giant cell tumours, and familial expansile osteolysis. 相似文献
969.
970.
K W Anquist S Panchanathan P C Rowe R G Peterson A Sirnick 《Canadian Medical Association journal》1991,145(8):965-968
OBJECTIVE: To determine whether the use of dimenhydrinate was associated with delay in the diagnosis and management of treatable illnesses or with direct adverse effects in children with vomiting presenting to an emergency department. DESIGN: Questionnaire survey and review of drug reaction and telephone inquiry records. SETTING: The emergency department of a tertiary care children's hospital and a provincial poison information centre. PATIENTS: The parents of 148 children who presented with vomiting completed the questionnaire. The database at the poison information centre included 474 reports of adverse drug reactions over an 8-year period and 105 reports of telephone inquiries over a 4-year period. MAIN RESULTS: Twenty-one (14%) of 148 children had received dimenhydrinate before arrival at the emergency department. The patients who had received dimenhydrinate were more likely than the others to present more than 12 hours after the onset of vomiting (14 [67%] of 21 v. 43 [34%] of 127, p less than 0.01). The discharge diagnoses for those who had received dimenhydrinate included asthma, pelvic inflammatory disease and urinary tract infection. No clinically important direct adverse reactions to dimenhydrinate were documented. CONCLUSIONS: The use of dimenhydrinate in children with vomiting is associated with a risk of delay in the diagnosis of treatable medical conditions. 相似文献