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   4779篇
  免费   515篇
  国内免费   26篇
耳鼻咽喉   41篇
儿科学   155篇
妇产科学   158篇
基础医学   656篇
口腔科学   107篇
临床医学   506篇
内科学   1214篇
皮肤病学   66篇
神经病学   266篇
特种医学   283篇
外科学   594篇
综合类   158篇
一般理论   1篇
预防医学   481篇
眼科学   93篇
药学   287篇
中国医学   4篇
肿瘤学   250篇
  2022年   31篇
  2021年   71篇
  2020年   47篇
  2019年   85篇
  2018年   67篇
  2017年   63篇
  2016年   83篇
  2015年   110篇
  2014年   134篇
  2013年   161篇
  2012年   195篇
  2011年   170篇
  2010年   170篇
  2009年   156篇
  2008年   185篇
  2007年   195篇
  2006年   199篇
  2005年   180篇
  2004年   166篇
  2003年   189篇
  2002年   175篇
  2001年   141篇
  2000年   157篇
  1999年   142篇
  1998年   83篇
  1997年   72篇
  1996年   75篇
  1995年   70篇
  1994年   65篇
  1993年   63篇
  1992年   108篇
  1991年   102篇
  1990年   105篇
  1989年   116篇
  1988年   97篇
  1987年   98篇
  1986年   87篇
  1985年   88篇
  1984年   58篇
  1983年   66篇
  1982年   51篇
  1981年   33篇
  1980年   46篇
  1979年   57篇
  1978年   51篇
  1977年   51篇
  1974年   40篇
  1973年   40篇
  1972年   33篇
  1971年   35篇
排序方式: 共有5320条查询结果,搜索用时 15 毫秒
21.
22.
23.
Adhesions and endometriosis are commonly encountered among patients presenting with pelvic or lower abdominal pain and also in a significant proportion of infertile patients. Laparoscopic investigation is usual in patients with these problems, and it has been possible to perform endoscopic surgery with special scissors and electrodiathermy. These methods can cause troublesome bleeding, and the diathermy produces high temperatures which can be hazardous if used in the vicinity of the bowel. The carbon dioxide laser can be used endoscopically to vaporize deposits of endometriosis and adhesions with great precision and virtually no bleeding. One hundred consecutive patients with endometriosis or adhesions were treated with the CO2 laser laparoscope and followed up for at least a year. Seventy-five per cent of patients with pain due to endometriosis were cured, and 68% of patients were better after laser laparoscopic adhesiolysis. Pregnancy rate in the previously infertile group with endometriosis was 64%. There were no complications due to the intra-abdominal use of CO2 laser energy under endoscopic control, although there is a need for a controlled trial. It appears that in the hands of an experienced laparoscopist this technique is safe and effective.  相似文献   
24.
Carotid endarterectomy has been established by two large randomised controlled trials (European Carotid Surgery Trial (ECST) and North American Symptomatic Carotid Endarterectomy Trial (NASCET)) as an important surgical procedure for the prevention of ischaemic strokes in patients presenting with transient cerebral ischaemia or non-disabling strokes attributable to severe ipsilateral carotid artery stenosis. The operation carries significant risk of death and stroke and it has been advocated by some that carotid endarterectomy should only be performed in a small number of designated regional centres in order to achieve good surgical results. It is doubtful that the regional centres alone can cope with the increasing numbers of patients requiring carotid endarterectomy and there is therefore a requirement for the procedure to be carried out by vascular surgeons in district general hospitals. It is important that surgical results are audited to ensure that comparable outcomes are achieved. We present an audit of our experience of carotid endarterectomy since 1981. A total of 149 consecutive carotid endarterectomies were performed by a single surgeon with a special interest in carotid surgery. The results are comparable to ECST with a 30-day mortality of 0% and an overall 30-day stroke rate of 5.7% (major strokes) for patients with severe, ie 70-99%, ipsilateral carotid artery stenoses. We have shown that carotid endarterectomy is an operation that can be performed safely and with good results by suitably trained surgeons in district general hospitals.  相似文献   
25.
Summary In Malaysia, Tinospora crispa extract is taken orally by Type 2 (non-insulin-dependent) diabetic patients to treat hyperglycaemia. We have evaluated the claimed hypoglycaemic property by adding aqueous extract to the drinking water of normal and alloxan-diabetic rats. After one week, fasting blood glucose levels were significantly (p<0.01) lower and serum insulin levels were significantly (p<0.01) higher in treated diabetic animals (10.4±1.0 mmol/l and 12.8±1.1 U/ml respectively) compared to untreated diabetic controls (17.4±1.7 mmol/l and 8.0±0.7 U/ml respectively). The insulinotropic action of T. crispa was further investigated in vitro using isolated human or rat islets of Langerhans and HIT-T15 cells. In static incubations with rat islets and HIT-T15 B cells, the extract induced a dosage dependent stimulation and potentiation of basal and glucose-stimulated insulin secretion respectively. This insulinotropic effect was also evident in perifused human and rat islets and HIT-T5 B-cells. The observations that (i) in all three models insulin secretory rates rapidly returned to basal levels on removal of the extract and (ii) in rat islets, a second challenge with T. crispa induced an additional, stimulated response, are all consistent with physiological release of insulin by B cells. Moreover, the rate of HIT-T15 glucose utilisation was not affected by incubation with T. crispa, suggesting that the cells were viable throughout. These are the first studies to provide biochemical evidence which substantiates the traditional claims for an oral hypoglycaemic effect of Tinospora crispa, and which also show that the hypoglycaemic effect is associated with increased insulin secretion.  相似文献   
26.
Summary The surfaces of 32 encrusted urinary catheters were examined by scanning electron microscopy to investigate the association of bacteria with the encrusting deposits. Deposits consisted of struvite crystals surrounded by aggregates of very small crystallites of hydroxyapatite. Underneath these minerals there was a layer of closely packed bacteria. Impressions of bacteria were also observed in hydroxyapatite. Crystals were often engulfed by the bacterial layer, which thus appeared to bind the crystals to each other and to the catheter surface. This thick layer of bacteria associated with crystals may protect both the bacteria from antibiotics and the crystals from acidic bladder washout solutions intended to dissolve them. Furthermore, the existence of this sessile population explains why urease-producing bacteria are not invariably detected in the urine of patients with encrusted catheters. The observation of this bacterial layer (or biofilm) by scanning electron microscopy provided direct evidence for infection being implicated in catheter encrustation.  相似文献   
27.
We report the first described case of Arthrographis kalrae pansinusitis and meningitis in a patient with AIDS. The patient was initially diagnosed with Arthrographis kalrae pansinusitis by endoscopic biopsy and culture. The patient was treated with itraconazole for approximately 5 months and then died secondary to Pneumocytis carinii pneumonia. Postmortem examination revealed invasive fungal sinusitis that involved the sphenoid sinus and that extended through the cribiform plate into the inferior surfaces of the bilateral frontal lobes. There was also an associated fungal meningitis and vasculitis with fungal thrombosis and multiple recent infarcts that involved the frontal lobes, right caudate nucleus, and putamen. Post mortem cultures were positive for A. kalrae.  相似文献   
28.
Helicobacter pylori-induced gastritis is an essential precursor lesion for the development of peptic ulcers or gastric adenocarcinoma. We demonstrate that nonresponsiveness to H. pylori SS1 infection is dominantly inherited in mice. F(1) hybrid crosses between a nonresponder mouse and three responder strains all possessed the nonresponder phenotype. Secretion of interleukin-10 but not gamma interferon was associated with nonresponsiveness to infection.  相似文献   
29.
pANCA is a marker antibody associated with inflammatory bowel disease (IBD), including most patients with ulcerative colitis and a subset with Crohn's disease. This study addressed the hypothesis that pANCA reacts with an antigen(s) of microbial agents potentially relevant to IBD pathogenesis. Using a pANCA monoclonal antibody, we have previously identified the C-terminal basic random-coil domain of histone H1 as a pANCA autoantigen. BLAST analysis of the peptide databases revealed H1 epitope homologues in open reading frames of the Mycobacterium tuberculosis genome. Western analysis of extracts from six mycobacterial species directly demonstrated reactivity to a single, conserved approximately 32-kDa protein. Direct protein sequencing, followed by gene cloning, revealed a novel 214-amino-acid protein, an iron-regulated protein recently termed HupB. Sequence analysis demonstrated its homology with the mammalian histone H1 gene family, and recombinant protein expression confirmed its reactivity with the 5-3 pANCA monoclonal antibody. Binding activity of patient serum immunoglobulin G (IgG) to HupB did not correlate with reactivity to histone H1 or pANCA, indicating the complex character of the pANCA antigen. However, anti-HupB IgA was strongly associated with Crohn's disease (P < 0.001). These findings indicate that the 5-3 pANCA monoclonal antibody detects a structural domain recurrent among mycobacteria and cross-reactive with a DNA-binding domain of histone H1. The association of HupB-binding serum IgA with IBD provides new evidence for the association of a mycobacterial species with Crohn's disease.  相似文献   
30.
The ability of three treatment schedules of mebendazole to kill well-established hydatid cysts was studied. Pregnant sheep, naturally infected withEchinococcus granulosus and/orTaenia hydatigena, were treated daily with mebendazole at a dose rate of 50 mg/kg body weight for either five days, one month, or three months.At autopsy, seven months after the commencement of treatment, no evidence was found that the 5-day treatment schedule had any damaging effect onE. granulosus cysts. The effects of the one month treatment were equivocal. There was evidence of a damaging effect from the 3-month treatment schedule and protoscoleces were not infective to dogs. NoT. hydatigena cysts survived the 1- and 3-month treatments, but organisms from the 5-day treatment were infective to dogs.These results forE. granulosus in sheep suggest that long-term treatment with mebendazole may be required in hydatid disease in man. The results obtained forT. hydatigena in sheep are discussed in relation to the treatment of cysticercosis fromT. solium in man. Mebendazole showed no untoward effect on the sheep or their lambs.  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