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   790篇
  免费   71篇
  国内免费   7篇
耳鼻咽喉   11篇
儿科学   37篇
妇产科学   8篇
基础医学   86篇
口腔科学   13篇
临床医学   87篇
内科学   158篇
皮肤病学   56篇
神经病学   52篇
特种医学   49篇
外科学   61篇
综合类   26篇
预防医学   91篇
眼科学   6篇
药学   86篇
中国医学   1篇
肿瘤学   40篇
  2021年   12篇
  2020年   18篇
  2019年   11篇
  2018年   17篇
  2017年   9篇
  2016年   15篇
  2015年   18篇
  2014年   22篇
  2013年   17篇
  2012年   35篇
  2011年   42篇
  2010年   30篇
  2009年   18篇
  2008年   30篇
  2007年   23篇
  2006年   39篇
  2005年   34篇
  2004年   31篇
  2003年   28篇
  2002年   23篇
  2001年   25篇
  2000年   16篇
  1999年   18篇
  1998年   24篇
  1997年   14篇
  1996年   20篇
  1995年   13篇
  1994年   15篇
  1993年   16篇
  1992年   18篇
  1991年   17篇
  1990年   9篇
  1989年   23篇
  1988年   16篇
  1987年   22篇
  1986年   18篇
  1985年   10篇
  1984年   14篇
  1983年   9篇
  1982年   9篇
  1981年   4篇
  1980年   6篇
  1979年   8篇
  1978年   3篇
  1976年   5篇
  1975年   4篇
  1974年   6篇
  1973年   5篇
  1969年   4篇
  1965年   3篇
排序方式: 共有868条查询结果,搜索用时 140 毫秒
71.
Chilaiditi syndrome is a rare condition defined by the presence of gastrointestinal symptoms associated with the radiological finding of segmental interposition of the bowel between the liver and the diaphragm. While it is infrequently indentified as a source of abdominal pain, Chilaiditi syndrome carries clinical significance as it can lead to a number of serious complications including intestinal obstruction, perforation, and ischemia. A 58-year-old woman presented with Chilaiditi syndrome immediately following colonoscopic evaluation. Conservative measures failed to alleviate the patient''s symptoms, and the patient ultimately elected to have operative management. Pexy of the cecum and ascending colon led to full resolution of her symptoms. To our knowledge, this is the first documented case of Chilaiditi syndrome iatrogenically induced by colonoscopy. Identification of this syndrome as a complication of colonoscopy and a source of post-procedural pain bears significance for providers involved in the peri-operative care of patients with factors predisposing them to the development of this condition.  相似文献   
72.
Several myelin-associated factors that inhibit axon growth of mature neurons, including Nogo66, myelin-associated glycoprotein (MAG) and oligodendrocyte myelin glycoprotein (OMgp), can associate with a common GPI-linked protein Nogo-66 receptor (NgR). Accumulating evidence suggests that myelin inhibitors also signal through unknown NgR-independent mechanisms. Here we show that MAG, a RGD tri-peptide containing protein, forms a complex with β1-integrin to mediate axonal growth cone turning responses of several neuronal types. Mutations that alter the RGD motif in MAG or inhibition of β1-integrin function, but not removal of NgRs, abolish these MAG-dependent events. In contrast, OMgp-induced repulsion is not affected by inhibition of b1-integrin function. We further show that MAG stimulates tyrosine phosphorylation of focal adhesion kinase (FAK), which in turn is required for MAG-induced growth cone turning. These studies identify β1-integrin as a specific mediator for MAG in growth cone turning responses, acting through FAK activation.  相似文献   
73.
The diagnostic value of biphasic radiographic examination of the stomach and duodenum was compared with that of fiberoptic endoscopy in a prospective, blinded study of 385 patients with dyspepsia. This investigation was directed at gastric malignancies and peptic ulcers. Methodologically there is no absolute standard for a study of this kind because histologic examination is useful for detection of cancer but inadequate for ulcers. As an alternative, kappa indexes and the sensitivity and specificity, as derived by Hui and Walter, were calculated and compared. For the detection of gastric carcinoma, radiographic and endoscopic findings had almost perfect agreement beyond chance. For gastric ulcers, radiography and endoscopy had substantial agreement, which became perfect if small ulcers (less than 5 mm) were excluded. For duodenal ulcers, radiography had a lower sensitivity than endoscopy; this disagreement disappeared if small ulcers were excluded. Both methods have equal merit; choice of the initial diagnostic procedure will therefore depend on cost, discomfort to the patient, and risk of complications.  相似文献   
74.
S Garnett  P Abrams 《The Practitioner》2001,245(1627):830-2, 834, 836 passim
  相似文献   
75.
76.
Aims To evaluate the effects of a jail‐based continuation of methadone maintenance therapy (MMT) on subsequent inmate recidivism risks. Design Prospective, longitudinal, observational study. Setting A large, Southwestern United States jail that continues MMT for heroin‐addicted inmates on MMT at the time of booking. Participants A total of 589 inmates booked between 22 November 2005 (the start date for the MMT program) and 31 October 2006. Measurements The outcome measure was time from release to subsequent re‐booking in the jail. Predictors included binary dosing with methadone in the jail, final dose received (mg), age, gender, race/ethnicity, previous bookings and days in jail. Findings and conclusions Random effects Weibull proportional hazards models were fit to the recidivism times to estimate the impact of treatment with MMT in the jail on re‐booking risks. There was no statistically significant effect of receiving methadone in the jail or dosage on subsequent recidivism risks (hazard ratio = 1.16; 95% confidence interval = 0.8–1.68). Offering jail‐based MMT does not increase recidivism risks by eliminating the deterrent effect of imposed withdrawal, nor does it reduce recidivism in this high‐risk population.  相似文献   
77.
78.
The pathophysiology of chorea in systemic lupus erythematosus (SLE) is uncertain. Pathologic examination has not identified a specific location for the causative lesion(s) and immunologic mechanisms have been suggested in its etiology. In other choreic disorders, such as Huntington's disease and benign hereditary chorea, glucose hypometabolism in the striatum has been demonstrated by positron computed tomography (PCT) using [18F]deoxyglucose. With this technique we have studied four patients with chorea secondary to SLE. In these patients the regional distribution of cerebral glucose metabolism was normal. In particular, striatal glucose metabolism was within the normal range, even though the ratio of striatal to cortical glucose metabolism was increased. Our results show that striatal hypometabolism, as seen in other disorders manifesting chorea, is not the PCT correlate of the dyskinesia.  相似文献   
79.
A case report of adrenocortical carcinoma is presented, and its natural history and treatment are discussed. Adrenocortical carcinoma is a rare malignant disease. The mean survival time for untreated patients is less than three months. The tumor is classified as functioning or nonfunctioning depending on biochemical and clinical evidence of steroid overproduction. Surgical resection of the tumor is the primary treatment. Chemotherapy is indicated for antitumor and antihormonal effects. Mitotane is a direct adrenolytic, and is the only drug currently available that has extended survival in patients with this disease. Its clinical usefulness is limited by its gastrointestinal and neurological toxicity. Aminoglutethimide inhibits steroid synthesis by blocking the conversion of cholesterol to pregnenolone. It has no antitumor effect in adrenocortical carcinoma, but is effective in relieving the signs and symptoms of excessive hormone production in functioning tumors. Both mitotane and aminoglutethimide have complex mechanisms of action. Their combined use in the treatment of adrenocortical carcinoma requires a complete understanding of their individual actions and awareness of the potential for additive effects, both therapeutic and toxic.  相似文献   
80.
The influence of polymer structure on the characteristics of complexes of a phosphorothioate antisense oligonucleotide (ISIS 5132) was studied, using well-defined cationic copolymers based on 2-(dimethylamino) ethyl methacrylate (DMAEMA) and poly(ethylene glycol) (PEG). The three related copolymer structures were: DMAEMA-PEG (a diblock copolymer) DMAEMA-OEGMA 7 (a brush-type copolymer), DMAEMA-stat-PEGMA (a comb-type copolymer); each of these were examined together with DMAEMA homopolymer, which served as a control. The results revealed that all the polymers exhibited good binding ability with the oligonucleotide (ON). Interestingly, the comb-type polymer DMAEMA-stat-PEGMA demonstrated the highest binding ability and DMAEMA homopolymer the lowest, as judged by a dye displacement assay. DMAEMA homopolymer produced large agglomerates of smaller individual complexes as observed by optical density, photon correlation spectroscopy and transmission electron microscopy studies. In contrast, two PEG-block copolymers, DMAEMA-PEG and DMAEMA-OEGMA 7, formed compact complexes of 80-150 nm which had good long-term colloidal stability. This is attributed to the steric stabilisation effect of the PEG chains on the ON-copolymer complexes. These two copolymers are believed to form complexes with ON that have a micellar structure. Comb-type DMAEMA-stat-PEGMA copolymer formed highly soluble complexes with the ON that did not phase separate from the buffer solution. This study clearly demonstrates that varying the copolymer architecture allows access to a range of ON complexes. In vitro cytotoxicity experiments on HepG2 cells showed that all of the tertiary amine methacrylate copolymers displayed lower cytotoxicity than the control poly(L-lysine).  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