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   345篇
  免费   26篇
  国内免费   8篇
儿科学   31篇
妇产科学   3篇
基础医学   42篇
口腔科学   11篇
临床医学   44篇
内科学   92篇
皮肤病学   7篇
神经病学   6篇
特种医学   63篇
外科学   15篇
综合类   10篇
预防医学   6篇
眼科学   3篇
药学   23篇
中国医学   1篇
肿瘤学   22篇
  2021年   3篇
  2020年   2篇
  2019年   5篇
  2018年   6篇
  2017年   6篇
  2016年   1篇
  2015年   7篇
  2014年   12篇
  2013年   9篇
  2012年   13篇
  2011年   8篇
  2010年   19篇
  2009年   16篇
  2008年   7篇
  2007年   10篇
  2006年   12篇
  2005年   10篇
  2004年   7篇
  2003年   10篇
  2002年   5篇
  2001年   8篇
  2000年   3篇
  1999年   10篇
  1998年   21篇
  1997年   18篇
  1996年   20篇
  1995年   14篇
  1994年   10篇
  1993年   6篇
  1992年   6篇
  1991年   5篇
  1990年   6篇
  1989年   11篇
  1988年   12篇
  1987年   9篇
  1986年   7篇
  1985年   5篇
  1984年   4篇
  1982年   4篇
  1981年   5篇
  1980年   4篇
  1979年   4篇
  1978年   1篇
  1977年   5篇
  1976年   6篇
  1975年   1篇
  1948年   2篇
  1932年   1篇
  1925年   1篇
  1924年   1篇
排序方式: 共有379条查询结果,搜索用时 15 毫秒
1.
2.
The authors describe their experience with methyl tertiary butyl ether (MTBE) in a larger series of patients than previously reported in order to acquaint physicians with both its effectiveness for dissolution of common bile duct calculi and the limitations of its use. Ten patients with 13 biliary calculi underwent percutaneous stone dissolution treatment with the experimental cholesterol solvent, MTBE. Three stones completely dissolved within 30 minutes, seven were reduced in size, and three were visibly unaffected. All stones not completely dissolved were easily extracted by means of a stone basket except for one in a patient taken to surgery. Although MTBE perfusion is an effective technique for management of biliary calculi, practitioners should be aware that its use is quite time consuming and its odor difficult to control.  相似文献   
3.
Expression of cadherins and CD44 isoforms in ovarian endometrial cysts   总被引:3,自引:0,他引:3  
We evaluated the immunohistochemical expression of cadherins and CD44 variants in 20 endometriomas, 20 cystadenomas, 20 borderline ovarian tumours as well as 20 ovarian carcinomas, and the serological and cystic fluid concentrations of soluble E-cadherin and soluble CD44 standard (sCD44sdt) in 20 endometriomas, 20 cystadenomas, six borderline and 11 carcinomas of the ovary. In endometriomas, immunostaining of E- and N-cadherin was negative (20 and 30% respectively). CD44 H, v3 and v6 immunostaining were detected in 63, 10 and 40% respectively. A difference in immunostaining for E-cadherin was found between endometriomas and cystadenomas (P < 0.001) and for N- cadherin between endometriomas and carcinomas (P < 0.001). A difference in CD44H immunostaining was observed between endometriomas and cystadenomas (P < 0.035) but not with borderline ovarian tumours and carcinomas. No difference in serum concentrations of soluble E- cadherins and CD44 standard was found between the four groups of tumours. Cystic fluid concentrations of E-cadherin were lower in endometriomas than in borderline tumours and ovarian carcinomas (P < 0.001). High concentrations of soluble CD44 standard cystic fluid were found in endometriomas than in other ovarian cysts. Endometriomas and borderline tumours share alterations of cadherins and CD44 isoforms which may help in the understanding of the aggressive and invasive potentials of endometriotic cells.   相似文献   
4.
Genital asymmetry in men   总被引:1,自引:0,他引:1  
This study examined genital asymmetry in a large sample of men. The probands were 6544 non-delinquent men who were interviewed by the Kinsey Institute for Research in Sex, Gender and Reproduction from 1938 to 1963. The measures were four indicators of penile and scrotal asymmetry, along with self-reported handedness, from Kinsey's interview protocol. Most men reported some degree of lateral asymmetry in their flaccid penis and in their testicles; less asymmetry was reported for their erect penis. The asymmetry typically occurred in the left direction, and this pattern occurred in both right- and nonright- handers. However, this 'leftward' pattern was significantly less pronounced in nonright-handers. The results are discussed in relation to previous findings of genital asymmetry in men, the possible relationship of genital asymmetry to functional cerebral asymmetry, and recent data suggesting genital asymmetry may predict patterns of cognitive performance and genital/sexual organ cancers.   相似文献   
5.
To evaluate the effect of endotoxin on the fibrinolytic response, we administered Escherichia coli endotoxin (4 ng per kilogram of body weight) intravenously to 19 healthy volunteers and measured fibrinolytic proteins, protease inhibitors, neutrophil elastase, and von Willebrand factor in serial blood samples obtained over 24 hours. One hour after endotoxin administration, the level of tissue plasminogen activator (t-PA) antigen rose from 10 to 23 ng per milliliter, peaking at 52 ng per milliliter at three hours. The level of alpha 2-plasmin inhibitor-plasmin complexes increased sevenfold, peaking at three hours. Plasminogen-activator inhibitor-1 activity rose more slowly, from 7 U per milliliter to a maximum of 49 U per milliliter at five hours. The concentrations of neutrophil elastase and von Willebrand antigen were unchanged at one hour, increased approximately threefold by 3 hours, and remained elevated at 24 hours. None of these measures changed in a control group (n = 5) given intravenous saline instead of endotoxin. We studied t-PA functional activity in four subjects. The level of activity rose rapidly, from 1.2 ng per milliliter at base line to 8.3 ng per milliliter at one hour and 13.9 ng per milliliter at two hours; it was undetectable at three hours. This increase in plasminogen activator activity was abolished in vitro by incubation of t-PA with an antiserum specific for human t-PA, suggesting that t-PA may be directly responsible for plasmin generation in the response to endotoxin. We conclude from this study of healthy subjects that endotoxin activates the fibrinolytic system, beginning with release of t-PA in the blood within one hour. The early activation of plasmin by endotoxin may prevent thrombosis, and the increase in fibrinolysis is then offset by the release of plasminogen activator inhibitor.  相似文献   
6.
Marked abnormalities in cardiovascular function accompany septic shock, and bacterial endotoxin is believed to be one of the principal mediators of these abnormalities. To evaluate the cardiovascular effects of endotoxemia in humans, we measured hemodynamic variables in nine normal subjects given an intravenous bolus dose of endotoxin (Escherichia coli, 4 ng per kilogram of body weight) and in six normal subjects given a bolus dose of saline, before and three hours after administration. All the subjects then underwent volume loading with normal saline (mean, 2217 ml) during the fourth and fifth hours after administration of the bolus, and the measurements were repeated. Three hours after the administration of endotoxin and before volume loading, the cardiac index had increased by 53 percent and the heart rate by 36 percent (both changes were significant; P less than or equal to 0.008), and the systemic vascular-resistance index had decreased by 46 percent (P = 0.004). After volume loading (five hours after the administration of endotoxin), the left ventricular ejection fraction decreased by 1 percent of the base-line value in the subjects given endotoxin, but increased by 14 percent in the controls (P = 0.008). The left ventricular end-diastolic and end-systolic volume indexes increased by 18 percent (P = 0.07) and 24 percent (P = 0.042), respectively. Left ventricular performance, as measured by the ratio of the peak systolic pressure to the end-systolic volume index, was depressed (a decrease of 0.90 in the subjects given endotoxin vs. an increase of 0.76 in the controls; P = 0.024). We conclude that the administration of endotoxin to normal subjects causes a depression of left ventricular function that is independent of changes in left ventricular volume or vascular resistance. The changes in function are similar to those observed in septic shock and suggest that endotoxin is a major mediator of the cardiovascular dysfunction in this condition.  相似文献   
7.
Bacterial sepsis is characterized by a systemic inflammatory state, with activation of numerous cell types. Phagocytes participate in this phenomenon by secreting various proinflammatory cytokines and enzymes. Matrix metalloproteinases (MMPs) such as gelatinases are produced by phagocytes and are thought to play an important role in processes of cell transmigration and tissue remodeling. In this work, we show that endotoxin (lipopolysaccharide [LPS]) and other inflammatory mediators, such as tumor necrosis factor (TNF), interleukin-8, and granulocyte colony-stimulating factor, induce a rapid (within 20 min) release of gelatinase-B (MMP-9) zymogen in whole human blood, as determined by gelatin zymography. The polymorphonuclear neutrophil was identified as the cell responsible for this rapid secretion, as a result of the release of preformed enzymes stored in granules. Normal human subjects given LPS intravenously showed a similar pattern of proMMP-9 secretion, with maximum plasma levels reached 1.5 to 3 h after LPS administration (P = 0.0009). Prior administration of TNF receptor:Fc, a potent TNF antagonist, to subjects given LPS, only partially blunted the release of proMMP-9 (P = 0.033). Ibuprofen, a cyclooxygenase inhibitor, did not alter this pattern of release. Increased levels of proMMP-9 and proMMP-2, as well as activated forms of MMP-9, were found in plasma from two patients with gram-negative sepsis. The levels of MMPs paralleled the severity of clinical condition and a marker of the severity of sepsis, plasma procalcitonin. These data indicate that MMPs are released in whole blood in response to various inflammatory mediators and that they could serve as sensitive and early markers for cell activation during the course of bacterial sepsis.  相似文献   
8.
Phospholipase A2 (PLA2) activity was measured in the serum of 23 individuals infused intravenously with endotoxin (EN) at a dose of 4 ng/kg body weight. A marked increase in PLA2 was noted 3 h after EN challenge (mean 828 ± 513 units/ml), reached its maximum at 24 h after the challenge (mean 2667 ± 2442 units/ ml), and was still evident at 48 h (mean 763 ± 366 units/ml). In contrast, TNF levels were maximal (mean 712 ± 375 pg/ml) 90 min after the EN challenge and subsided to very low values (5 ± 5 pg/ml) 5 h after the challenge. There was a positive correlation between the maximum response of TNF and that of PLA2 (r = 0.82,P < 0.01). Administration of ibuprofen or pentoxifylline did not alter the PLA2 response. EN challenge did not affect serum pancreatic PLA2 concentration or that of the lysosomal cationic enzyme, lysozyme. Neutralizing antibody against human recombinant (synovial type) PLA2 completely abolished PLA2 activity in the sera tested. We conclude that EN infusions cause marked intravascular release of nonpancreatic secretory PLA2 and that the magnitude of this response seems to be related to the prior generation of TNF.  相似文献   
9.
Immune deficiencies in chronic intestinal pseudo-obstruction   总被引:1,自引:0,他引:1  
Aim: Chronic intestinal pseudo-obstruction has been associated with urinary disorders, myopathy, and ophthalmoplegia in adults and cholelithiasis in children. We observed a high percentage of total-parenteral-nutrition-dependent patients with pseudo-obstruction and recurrent infections requiring gammaglobulin infusions. Methods: AH records for 23 children with chronic intestinal pseudo-obstruction (10 females and 13 males, mean age 9.8 y ± 4.9 y, range 4–24 y) referred for a nutritional evaluation from 1992 to 1995 were reviewed. Chronic intestinal pseudo-obstruction was diagnosed by clinical, radiographic findings and antroduodenal manometry. Intestinal full-thickness biopsies were performed in seven children. Results: Hypogammaglobulinemia was diagnosed in 18 patients (78%): 16 patients had various immunoglobulin deficiencies and 2 had selective antibody deficiency. Intravenous gammaglobulin was administered in 14 patients. Other medical conditions affecting the children are summarized as follows: autonomic dysfunction in 10 patients (43%), recurrent hypoglycemia in 9 (39%), asthma in 9 (39%), cholecystitis in 7 (30%), low serum carnitine level in 6 (26%), urinary dysfunction in 6 (26%), pancreatitis in 5 (22%), behavioral problems in 5 (22%), myopathy in 2 (9%), idiopathic thrombocytopenia in 2 (8%), velopharyngeal insufficiency in 1 (4%), oculocutaneous albinism in 1 (4%), Pierre-Robin syndrome in 1 (4%), and protein C deficiency in 1 (4%). Munchausen syndrome was suspected in two patients. Conclusions: Chronic intestinal pseudo-obstruction appears to be associated with immune deficiencies. It is unclear if the immune deficiencies, intestinal pseudo-obstruction, and the other medical conditions have a common underlying etiology. Repeated infections may be due to impaired immune function in children with chronic intestinal pseudo-obstruction. We recommend screening for immune deficiencies in children with chronic intestinal pseudo-obstruction.  相似文献   
10.
Complications from improperly placed biliary stents are not uncommon. Free loose wires from the ends of an uncovered stent can irritate and damage adjacent mucosal surfaces. Effective management can be achieved via percutaneous placement of a second stent to alter the orientation of the original stent.  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