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   40715篇
  免费   1854篇
  国内免费   177篇
耳鼻咽喉   689篇
儿科学   668篇
妇产科学   734篇
基础医学   5316篇
口腔科学   1238篇
临床医学   2862篇
内科学   9502篇
皮肤病学   545篇
神经病学   3345篇
特种医学   1346篇
外科学   7062篇
综合类   180篇
一般理论   2篇
预防医学   1488篇
眼科学   626篇
药学   3422篇
中国医学   78篇
肿瘤学   3643篇
  2022年   403篇
  2021年   693篇
  2020年   350篇
  2019年   491篇
  2018年   585篇
  2017年   451篇
  2016年   552篇
  2015年   600篇
  2014年   778篇
  2013年   1035篇
  2012年   1657篇
  2011年   1771篇
  2010年   1028篇
  2009年   875篇
  2008年   1710篇
  2007年   1856篇
  2006年   1808篇
  2005年   1775篇
  2004年   1733篇
  2003年   1777篇
  2002年   1724篇
  2001年   1619篇
  2000年   1772篇
  1999年   1494篇
  1998年   480篇
  1997年   386篇
  1996年   361篇
  1995年   302篇
  1994年   281篇
  1993年   248篇
  1992年   1105篇
  1991年   921篇
  1990年   899篇
  1989年   944篇
  1988年   835篇
  1987年   832篇
  1986年   783篇
  1985年   770篇
  1984年   527篇
  1983年   422篇
  1982年   218篇
  1979年   483篇
  1978年   274篇
  1977年   251篇
  1975年   207篇
  1974年   223篇
  1972年   205篇
  1971年   230篇
  1969年   230篇
  1968年   216篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
We describe a case of aldosterone-producing adrenocortical adenoma (APA) associated with a probable post-operative adrenal crisis possibly due to subtle autonomous cortisol secretion. The patient was a 46-year-old female who suffered from severe hypertension and hypokalemia. CT and MRI scans revealed a 2-cm diameter adrenal mass. The patient's plasma aldosterone level was increased, and her plasma renin activity was suppressed, both of which findings were consistent with APA. Cushingoid appearance was not observed. Morning and midnight serum cortisol and plasma adrenocorticotropic hormone (ACTH) levels were all within the normal range. Her serum cortisol level was suppressed to 1.9 microg/dl as measured by an overnight 1-mg dexamethasone suppression test, but was incompletely suppressed (2.7 microg/dl) by an overnight 8-mg dexamethasone suppression test. In addition, adrenocortical scintigraphy showed a strong uptake at the tumor region and a complete suppression of the contra-lateral adrenal uptake. After unilateral adrenalectomy, she had an episode of adrenal crisis, and a transient glucocorticoid replacement improved the symptoms. Histopathological studies demonstrated that the tumor was basically compatible with APA. The clear cells in the tumor were admixed with small numbers of compact cells that expressed 17alpha-hydroxylase, suggesting that the tumor was able to produce and secrete cortisol. In addition, the adjacent non-neoplastic adrenal cortex showed cortical atrophy, and dehydroepiandrosterone sulfotransferase immunoreactivity in the zonae fasciculata and reticularis was markedly diminished, suggesting that the hypothalamo-pituitary-adrenal (HPA) axis of the patient was suppressed due to neoplastic production and secretion of cortisol. Together, these findings suggested that autonomous secretion of cortisol from the tumor suppressed the HPA axis of the patient, thereby triggering the probable post-operative adrenal crisis. Post-operative adrenocortical insufficiency should be considered in clinical management of patients with relatively large APA, even when physical signs of autonomous cortisol overproduction are not apparent.  相似文献   
2.
Regional effects of craniotomy on cerebral circulation and metabolism, such as regional cerebral blood flow (rCBF), regional cerebral oxygen consumption (rCMRO2), regional oxygen extraction fraction (rOEF), and regional cerebral blood volume (rCBV) were examined by a PET (positron emission tomography) study concerning surgery that was performed on unruptured aneurysm patients. Eight patients with intracranial un-ruptured aneurysms were studied pre- and post-operatively by the 15O labelled-gas steady-state method, using HEADTOME-III. All patients underwent aneurysmal surgery performed by the transsylvian approach. There was a significant increase in the mean OEF values taken from the whole-brains of 8 patients, but there was not a significant change in CBF, CMRO2 or CBV. The increase in OEF was caused by decrease of O2 content, which was caused by post-operative decrease in the Hb value. So, this OEF increase was not the direct effect of craniotomy. In 2 patients, the rCBF and rCMRO2, in the fronto-temporal region (where craniotomy was performed) increased post-operatively. This regional effect suggests transient reactive hyperemia following compressive ischemia during the operative procedure, and metabolic demands for recovery of brain function. In 2 other patients, who had relatively low rCBFs during the pre-operative study, rCBF and rCMRO2 in the bi-frontal region had decreased more at the post-operative study. This change appears to have been caused by removal of cerebrospinal fluid and depression of the frontal lobe. From this study, it becomes evident that the regional effect of craniotomy on cerebral circulation and metabolism is not so great, when adequate microsurgical techniques are used.  相似文献   
3.
To investigate the role of cell-mediated immunity (CMI) in glomerulonephritis (GN), we identified the infiltrating immune cells both within the glomerulus and in the interstitium. Frozen sections from 103 patients with various forms of GN: 10 with minor glomerular abnormality (MGA) as control, 10 with minimal change nephrotic syndrome (MCNS), 10 with membranous nephropathy (MN), 9 with focal glomerulosclerosis (FGS), 30 with IgA nephropathy (IgAN), 22 with acute post streptococcal glomerulonephritis (APSGN), and 2 with rapidly progressive glomerulonephritis (RPGN) were examined using monoclonal antibodies (MoAb) by indirect immunoalkaline-phosphatase labelling. In most glomerulonephritis, monocyte/M phi and helper/inducer T cells were predominantly infiltrating in the interstitium, but intraglomerular infiltration was rare, except for APSGN. This interstitial infiltration increased proportionally to the level of serum creatinine, and was most prominent in RPGN. Apparently different distribution was seen in APSGN, that is, prominent increase in total number of intra-glomerular monocyte/M phi infiltration with slightly increased T cells. The change was correlated with time after onset; namely the more leucocytic infiltration was observed when the tissue was taken earlier. These data suggest that in APSGN, monocyte/M phi accumulate in glomeruli via cell mediated immunity in addition to humoral immune mechanism resulting in glomerular hypercellularity, whereas in most chronic glomerulonephritis interstitial leucocyte infiltration, particularly helper T cells and monocyte/M phi may play an important role in the progression of glomerulonephritis.  相似文献   
4.
5.
6.
Recent genome-wide high-throughput (HTS) analyses of protein–protein interactions (PPIs) provide molecular-based information to uncover functions of cells and tissues, such as those of the mammalian brain. However, the HTS PPI data contain much false-negatives and false-positives, which should be primarily addressed in experiments. Integrating PPI data sets with other genome-wide data, such as expression profiles and phenotype data sets, provides novel biological insights. Such integration analysis is valuable for addressing the complexity of the mammalian brain. Discovery of novel interactions followed by a detailed analysis is a successful approach to uncover the function of proteins. For example, extensive PPI screens for parkin , a hereditary Parkinson's disease gene, elucidated the function of parkin as an E3 ubiquitin ligase, with localization and activity regulated by contact with its interaction partners, uncovering at least a part of the molecular pathogenesis of Parkinson's disease.  相似文献   
7.
AIMS: A rare case of the insulin autoimmune syndrome (IAS) accompanied by insulin receptor anomaly is reported. METHODS: Antibodies to insulin and insulin receptor were determined in the patient with severe hypoglycaemia before and after the treatment with prednisolone. RESULTS: Titers of antibody to insulin and insulin receptors were 73.0% and 41.5%, respectively. Drug-induced lymphocyte stimulation tests were all negative for the suspicious drugs. Her HLA-DR was DRB1*0403/04051. Following steroid therapy, the formation of antibodies was suppressed and alleviated her symptoms. Scatchard analysis yielded findings specific to polyclonal antibodies. CONCLUSIONS: The changes in autoantibodies resulted in alleviation of the hypoglycemic symptoms as a result of steroid therapy.  相似文献   
8.
Background: Buried bumper syndrome (BBS) is a rare complication of percutaneous endoscopic gastrostomy (PEG). Along with the widespread use of the button‐type kit, BBS is encountered frequently. Methods: In the present study, we examined causes and treatments for BBS among 1400 patients who had undergone PEG. Results: The causes of BBS after PEG were classified into two categories: early causes consisted of wound infection, inappropriate size of kit and severe lordosis, while late causes were inappropriate exchange of kit, rough management or weight gain. The treatments for BBS could be determined by the degree of wound infection, fistula and burial of the bumper. Conclusion: We prepared a flowchart for replacement, by which BBS can be managed safely and quickly without surgical or endoscopic intervention.  相似文献   
9.
OBJECTIVES: Laparoscopic surgery for kidney treatment is a common procedure. However, the efficacy of this procedure in patients with several comorbidities has not been well investigated. We conducted a retrospective comparison of results of laparoscopic surgery between patients with several comorbidities and patients with no comorbidity to access the efficacy and safety of this procedure. METHODS: The subjects were 20 patients with three or more comorbidities (group A) and 46 patients with less than three comorbidities (group B). These 66 patients were 48 men and 18 women with a mean age of 62.3 years (age range, 24-83 years). The data from these two groups were compared for American Society of Anesthesiology (ASA) physical status score, previous surgical history, duration of surgery, estimated blood loss, tumor size, complications during and after surgery, conversion rates, time to oral intake, and length of hospital stay. RESULTS: The initial ASA score and age were significantly higher for the patients with comorbidities (P < 0.0001, P = 0.0008, respectively). All other variables before, during, and after surgery were similar for both laparoscopic groups. However, the incidence of atelectasis of laparoscopy was higher than that of open surgery. CONCLUSIONS: Laparoscopic nephrectomy for patients with comorbidities is safe and minimally invasive. Further investigation to prevent atelectasis is necessary.  相似文献   
10.
The presence of blood in the ejaculate is called hematospermia or hemospermia. While often perceived as a symptom of little significance, hematospermia can cause great concern to men who experience it. We report an unusual case of hematospermia associated with pelvic arteriovenous malformation (AVM). A 60-year-old man who visited our hospital complaining of hematospermia and pollakisuria was found to have AVM and aneurysmal changes in the left side of the pelvis using computed tomography (CT). The patient was treated with steel coil embolization of the left inferior gluteal artery, and after the procedure the hematospermia and pollakisuria remained absent without flare-ups.  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