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   1314篇
  免费   81篇
  国内免费   12篇
耳鼻咽喉   29篇
儿科学   72篇
妇产科学   10篇
基础医学   145篇
口腔科学   38篇
临床医学   166篇
内科学   324篇
皮肤病学   20篇
神经病学   97篇
特种医学   196篇
外科学   109篇
综合类   49篇
预防医学   66篇
眼科学   13篇
药学   21篇
肿瘤学   52篇
  2022年   8篇
  2020年   10篇
  2018年   14篇
  2017年   12篇
  2016年   9篇
  2015年   18篇
  2014年   16篇
  2013年   34篇
  2012年   36篇
  2011年   41篇
  2010年   40篇
  2009年   36篇
  2008年   46篇
  2007年   63篇
  2006年   65篇
  2005年   41篇
  2004年   50篇
  2003年   32篇
  2002年   33篇
  2001年   36篇
  2000年   34篇
  1999年   33篇
  1998年   36篇
  1997年   34篇
  1996年   50篇
  1995年   26篇
  1994年   20篇
  1993年   27篇
  1992年   31篇
  1991年   29篇
  1990年   38篇
  1989年   26篇
  1988年   51篇
  1987年   30篇
  1986年   33篇
  1985年   25篇
  1984年   20篇
  1983年   26篇
  1982年   11篇
  1981年   19篇
  1980年   9篇
  1979年   11篇
  1978年   11篇
  1977年   18篇
  1976年   11篇
  1975年   11篇
  1974年   16篇
  1973年   11篇
  1972年   7篇
  1971年   12篇
排序方式: 共有1407条查询结果,搜索用时 15 毫秒
1.
2.
3.
BACKGROUND: Caecal intubation is a necessary step in the complete endoscopic evaluation of the colon. Studies have estimated that experienced colonoscopists may fail to reach the caecum in up to 10% of cases. AIMS: To evaluate the utility of the double balloon enteroscope used for complete examination of the colon in patients with incomplete standard colonoscopy. PATIENTS: Twenty consecutive patients with incomplete colonoscopies within the Veterans Affairs Palo Alto Health Care System. Mean age of 66 years (S.D.+/-12 years, range 46-84), 16 men. METHODS: Prospective single-centre case series on the caecal intubation rate using standard double balloon enteroscope technique in patients with previous incomplete conventional colonoscopy. RESULTS: Use of the standard double balloon enteroscope technique permitted complete colonoscopy to be achieved in 95% of the patients (19/20). Seven patients (35%) had significant pathology beyond the extent of the prior incomplete colonoscopy. We performed endoscopic mucosal resection, polypectomy or biopsy. The mean time to reach the caecum was 28 min (S.D.+/-20 min, range 6-90 min). The sedation was similar to conventional colonoscopy. No complications occurred. CONCLUSIONS: The double balloon enteroscope technology and technique can be used to complete examination of the colon in patients who were referred because of incomplete standard colonoscopy.  相似文献   
4.
de Vries Reilingh  TS  van Geldere  D  Langenhorst  BLAM  de Jong  D  van der Wilt  GJ  van Goor  H  Bleichrodt  RP 《Hernia》2004,8(1):56-59
Polypropylene mesh is widely used for the reconstruction of incisional hernias that cannot be closed primarily. Several techniques have been advocated to implant the mesh. The objective of this study was to evaluate, retrospectively, early and late results of three different techniques, onlay, inlay, and underlay. The records of 53 consecutive patients with a large midline incisional hernia — 25 women and 28 men, mean age 60.4 (range 28–94) — were reviewed. Polypropylene mesh was implanted using the onlay technique in 13 patients, inlay in 23 patients, and underlay in 17 patients. Either the greater omentum or a polyglactin mesh was interponated between the mesh and the viscera. The records of these 53 patients were reviewed with respect to: size and cause of the hernia, pre- and postoperative mortality and morbidity, with special attention to wound complications. Patients were invited to attend the outpatient clinic at least 12 months after implantation of the mesh for physical examination of the abdominal wall. Postoperative complications occurred in 14 (26.4%) patients. The onlay technique had significantly more complications, as compared to both other techniques. Reherniation occurred in 15 (28.3%) patients. The reherniation rate of the inlay technique was significantly higher than after the underlay technique (44% vs 12%, P=0.03) and tended to be higher than the onlay technique (44% vs 23%, P=0.22). Repair of large midline incisional hernias with the use of a polypropylene mesh carries a high risk of complications and has a high reherniation rate. The underlay technique seems to be the better technique.  相似文献   
5.
6.
Kuross  SA; Hebbel  RP 《Blood》1988,72(4):1278-1285
Previous studies documented the abnormal association of heme and heme proteins with the sickle RBC membrane. We have now examined RBC ghosts and inside-out membranes (IOM) for the presence of nonheme iron as detected by its formation of a colored complex with ferrozine. Sickle ghosts have 33.8 +/- 18.2 nmol nonheme iron/mg membrane protein, and sickle IOM have 4.3 +/- 3.0 nmol/mg. In contrast, normal RBC ghosts and IOM have no detectable nonheme iron. The combination of heme and nonheme iron in sickle IOM averages nine times the amount of membrane- associated iron in normal IOM. Kinetics of the ferrozine reaction show that some of this nonheme iron on IOM reacts slowly and is probably in the form of ferritin, but most (72% +/- 18%) reacts rapidly and is in the form of some other biologic chelate. The latter iron compartment is removed by deferoxamine and by treatment of IOM with phospholipase D, which suggests that it represents an abnormal association of iron with polar head groups of aminophospholipids. The biologic feasibility of such a chelate was demonstrated by using an admixture of iron with model liposomes. Even in the presence of tenfold excess adenosine diphosphate, iron partitions readily into phosphatidylserine liposomes; there is no detectable association with phosphatidylcholine liposomes. To examine the bioavailability of membrane iron, we admixed membranes and t-butylhydroperoxide and found that sickle membranes show a tenfold greater peroxidation response than do normal membranes. This is not due simply to a deficiency of vitamin E, and this is profoundly inhibited by deferoxamine. Thus, while thiol oxidation in sickle membranes previously was shown to correlate with heme iron, the present data suggest that lipid peroxidation is related to nonheme iron. In control studies, we did not find this pathologic association of nonferritin, nonheme iron with IOM prepared from sickle trait, high-reticulocyte, postsplenectomy, or iron-overloaded individuals. These data provide additional support for the concept that iron decompartmentalization is a characteristic of sickle RBCs.  相似文献   
7.
8.
This paper presents two unusual fistulae between the rectum and the lower urinary tract in adults, one a posttraumatic fistula following dilatation of a sigmoid colon stricture and the other a congenital anomaly. In both cases a contrast enema was negative; in one case a voiding cystourethrogram was negative. The fistula was demonstrated in case 1 by repeating the enema and having the patient raise his intraabdominal pressure, and in case 2 by having the patient hold while attempting to pass flatus during a cystogram, which demonstrated gas bubbles entering the bladder.  相似文献   
9.
We evaluated the efficacy of murine monoclonal antibodies (Mabs) targeted to beta/A4 amyloid for development of procedures for the in vivo identification of amyloid angiopathy (AA) in Alzheimer's disease (AD). Mabs to beta/A4 amyloid were prepared and screened for effectiveness in visualizing AA and senile plaques in postmortem AD brain sections. They were assessed again after enzymatic cleavage to produce Fab fragments and after labeling with 99mTc using a diamide dimercaptide ligand system. Modified and radiolabeled Fab fragments retained activity and specificity towards amyloid-laden blood vessels and senile plaques. A highly specific murine Mab, 10H3, was identified and characterized that fulfills criteria necessary for the development of a diagnostic imaging agent. Expansion and adaptation of these strategies may provide the methods and materials for the noninvasive analysis of AA in living patients, and permit assessment of the contribution of AA to the clinical and pathological features of AD.  相似文献   
10.
By the end of 1990, 51 symptomatic children with perinatally acquired HIV infection had been admitted to Baragwanath Hospital. Of 42 children who were followed up for at least 3 months, 15 (35.7%) died and 16 (38.1%) were lost to follow-up. The case fatality rate for these children lies between 35.7% and 73.8%. Most children became symptomatic before the age of 6 months and presenting features seen in over 70% of cases included lymphadenopathy, failure to thrive and hepatomegaly. Surviving children had recurrent admissions to hospital, predominantly for respiratory distress. Many had bacterial pneumonias. Cardiac involvement (cardiomyopathy and cor pulmonale), recurrent serious bacterial infections and neurodevelopmental abnormalities were common. Our experience confirms that vertically acquired HIV infection has a relatively short incubation period and progresses rapidly with cardiorespiratory symptoms predominating. Five HIV seroprevalence studies have been conducted in pregnant women attending Baragwanath Hospital and the Soweto clinics since 1988. The calculated doubling time is between 7 and 21 months. At the end of 1990 the HIV seroprevalence rate in pregnant women was 0.82% (95% confidence limits 0.44-1.19%).  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