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   5768篇
  免费   341篇
  国内免费   43篇
耳鼻咽喉   50篇
儿科学   175篇
妇产科学   113篇
基础医学   576篇
口腔科学   66篇
临床医学   534篇
内科学   1133篇
皮肤病学   103篇
神经病学   767篇
特种医学   131篇
外科学   1197篇
综合类   24篇
预防医学   364篇
眼科学   73篇
药学   294篇
中国医学   31篇
肿瘤学   521篇
  2023年   60篇
  2022年   118篇
  2021年   251篇
  2020年   131篇
  2019年   244篇
  2018年   220篇
  2017年   155篇
  2016年   163篇
  2015年   192篇
  2014年   264篇
  2013年   261篇
  2012年   401篇
  2011年   436篇
  2010年   273篇
  2009年   199篇
  2008年   328篇
  2007年   317篇
  2006年   286篇
  2005年   261篇
  2004年   236篇
  2003年   231篇
  2002年   211篇
  2001年   93篇
  2000年   103篇
  1999年   81篇
  1998年   40篇
  1997年   36篇
  1996年   38篇
  1995年   30篇
  1994年   28篇
  1993年   25篇
  1992年   54篇
  1991年   39篇
  1990年   55篇
  1989年   45篇
  1988年   27篇
  1987年   36篇
  1986年   21篇
  1985年   17篇
  1984年   18篇
  1983年   13篇
  1982年   12篇
  1981年   8篇
  1980年   7篇
  1979年   14篇
  1978年   10篇
  1977年   8篇
  1976年   9篇
  1975年   6篇
  1966年   8篇
排序方式: 共有6152条查询结果,搜索用时 15 毫秒
61.
62.
Presentation of one case of scrotal hernia in a man of 64 years old patient. Diagnosed by cistography and ultrasound and treated by herniorraphy and posterior transuretral litolaplaxy of a vesical litiasis and RTU of prostate. Postoperative urography showed normal vesical morphology.  相似文献   
63.
Lower urinary tract obstruction in women is an uncommon condition resulting from multiple either organic or functional disorders. This paper contributes one case of obstructive uropathy secondary to presence of almost complete vulvar synechia due to extreme genital atrophy, a rare entity that may appear in postmenopausal women. Partial and incomplete vulvar fusion usually occurs in significant postmenopausal atrophies, sometimes associated to urethral meatus stricture; this, however, has no significant repercussion on urination dynamics. No other comparable case was found in the reviewed literature.  相似文献   
64.
We performed this case–control study to evaluate the risk of hypoglycemia associated with the use of antihypertensive drugs in older hospitalized diabetic patients treated with sulfonylureas and/or insulin. All diabetic patients admitted during 4 months in 1988, 1 month in 1991, 4 months in 1993 and 4 months in 1995 (n = 3477, mean age 71.4 ± 0.2 years, 1542 males and 1935 females) were enrolled in the study. During the four annual surveys 86 patients (mean age 71.1 ± 1.4 years, 33 males and 53 females) presented hypoglycemia during hospital stay. The patients who presented hypoglycemia were less frequently users of sulfonylureas and more frequently users of a combination of insulin and sulfonylureas. Use of antihypertensive drugs was similar in the two groups studied, and among potentially interacting drugs considered in the analysis, sulfonamides were more frequently used in patients who experienced hypoglycemia. Moreover, patients with hypoglycemia used a higher number of drugs, had a longer length of stay and had a greater prevalence of hypoglycemia as admission problem. Finally, although not significant, liver and renal diseases were more frequent among patients with hypoglycemia. In the multivariate analysis, contemporary use of insulin and sulfonylureas, liver disease and length of stay were significantly associated with hypoglycemia, while none of the antihypertensive drugs showed a significant association with the occurrence of hypoglycemia during hospital stay. Our results indicate that antihypertensive drugs do not increase the risk of hypoglycemia in elderly diabetic patients.  相似文献   
65.
The authors analyze the incidence of early mechanical and infective CSF shunt complications and various factors that might be correlated with the incidence in a series of 170 children affected by hydrocephalus and meningomyelocele (MM), with the aim of finding specific risk factors related to this particular type of hydrocephalus. Factors investigated for correlation with CSF shunt malfunction are the following: level of the spinal malformation, age of the patient at MM repair, age at diagnosis of hydrocephalus, degree of the ventricular dilatation, age at CSF shunt implantation, modality of the surgical procedure, characteristics of CSF at operation. In the first postoperative year following CSF shunting, 45.9% of the patients presented one shunt malfunction, three-quarters of which were due to mechanical causes, and one quarter to infection. Age of the patient at diagnosis of hydrocephalus and at CSF shunt operation did not significantly influence shunt patency, nor did the surgical modality (programmed vs emergency procedure). On the other hand, MM level did influence the outcome of CSF shunting: a higher percentage of malfunctions (and in particular of infective complications) was observed among the patients with high level MMs than in the group with more caudal location of the spinal defect. Similarly, the degree of ventricular dilatation correlated with the incidence of complications (more severe ventricular dilatation was associated with the highest incidence of complications). The order in which MM repair and CSF shunting were carried out and the age of the patients at MM repair did not affect the occurrence of mechanical complications, whereas they had a significant effect on the incidence of infective complications. In fact, the rate of overall complications, and of infective complications in particular, was proportional the age at MM repair. Furthermore, the group of children who underwent to MM repair and CSF shunting simultaneously scored the lowest percentage of complications, although these were mainly infections; the highest incidence of complications (and in particular of infective ones) was observed in the children who underwent CSF shunting first. The most striking correlation, however, was found with the characteristics of CSF. While normal CSF values correlated with an overall incidence of complications of 39.2%, abnormal CSF values were correlated with a rate of complications of 90.9%; in particular, the rates of infective complications were 2.7% and 77.3%, respectively. On the grounds of these observations a protocol is proposed of temporary CSF external drainage in children requiring prompt relief of increased intracranial pressure but at risk for the presence of a leaking spinal defect or of a MM left unrepaired for more than 48 h.  相似文献   
66.
Employing quantitative autoradiography, pineal body glucose utilization (GU) was measured in daytime or at night in prepubertal (aged 1 month), adult (aged 3 months), and mature (over 12 months old) rats. In prepubertal and adult rats, in daytime, GU values within the pineal tissue were homogeneously distributed around 65 mol glucose/100 g per min. In prepubertal animals no significant variations in GU were observed between daytime and nocturnal measurements. A circadian metabolic rhythmicity was evident in adult rats, with a GU peak measured at 2 a.m. In mature animals, GU also varied between day and night, with an increment in the relative difference between the two values. The present investigation is the first to demonstrate that circadian metabolic rhythmicity is absent before sexual maturation while it is enhanced in 12-month-old rats. These changes in pineal energy metabolism with advancing age are intriguing in view of the concept that the pineal gland may be involved in functional changes occurring during the process of aging.  相似文献   
67.
OBJECTIVE: In addition to sex steroids, prolactin (PRL) may also stimulate prostate cancer growth. Abnormally high blood levels of PRL have been noted in metastatic prostate cancer patients. However, most studies have been limited to the evaluation of basal levels of PRL rather than to investigate its secretion in response to classical endocrine dynamic tests. This study was carried out to analyze PRL secretion in metastatic prostate cancer patients both at basal conditions and in response to L-Dopa and metoclopramide, which represents the most classical inhibitory and stimulatory tests for PRL secretion, respectively. METHODS: The study included 12 patients with metastatic prostate cancer. On separate occasions, PRL secretion was evaluated in response to L-Dopa (500 mg orally) and to metoclopramide (10 mg i.v. as a bolus). Serum levels of PRL were measured by RIA. RESULTS: Mean PRL concentrations significantly increased after metoclopramide administration, even though no PRL response occurred in 6 of 12 patients. L-Dopa was unable to reduce PRL levels, which, in contrast, paradoxically significantly increased in response to L-Dopa, with mean values comparable to those achieved after metoclopramide injection. CONCLUSION: By showing a paradoxical stimulatory effect of L-Dopa on PRL secretion and a lack of response to metoclopramide in some patients, this study would suggest the existence of evident alterations in the neuroendocrine regulation of PRL release in advanced prostate cancer.  相似文献   
68.
Advanced stage ovarian cancer has a high rate of recurrence even after surgery followed by chemotherapy combining carboplatin and a taxane. New strategies are currently under way to combat this situation and one of the most promising ones is based on the knowledge that angiogenesis, the mechanism of formation of new blood vessels coupled with the degradation of the extracellular matrix for metalloproteinases, could be crucial in the development of this tumor. The principal molecule implicated in angiogenesis process of ovarian cancer is the vascular endothelial growth factor (VEGF). Several studies are now in progress to clarify its role as a diagnostic tool or its therapeutic implication. Presently, there is no indication for the use of VEGF in a preliminary diagnosis seeing that an increase in levels can be seen in both benign and malignant ovarian conditions. VEGF is also responsible for an increase in vascular permeability and is directly related to symptoms such as ascites and pleural effusion, both of which are frequent in ovarian cancer. Several papers have analised the role of VEGF as a prognostic factor and some of them do confirm VEGF as an independent prognostic factor in ovarian cancer. VEGF and the metalloproteinase system coupled with angiogenesis are currently being evaluated as therapeutic targets but no positive results have yet to be seen in this field.   相似文献   
69.
Loss of beta-catenin expression in metastatic gastric cancer.   总被引:10,自引:0,他引:10  
PURPOSE: Beta-catenin (beta-catenin) participates in intercellular adhesion and is an integral part of the Wnt signaling pathway. The role of beta-catenin in the pathogenesis of gastric cancer and its metastasis is largely unknown. PATIENTS AND METHODS: Immunohistochemistry and Western blot analysis were used to analyze the expression of beta-catenin in 87 human gastric cancers, in metastasis and cancer cell lines. The beta-catenin and the adenomatous polyposis coli (APC) genes were analyzed for gene mutations. Furthermore, methylation of the beta-catenin promoter in cell lines was assessed by treatment with 5'-azadeoxycytidine and sodium bisulfite genomic sequencing. RESULTS: beta-Catenin expression was present at either the cell membrane or the cytoplasm in 34 of 75 primary gastric cancers. Expression of beta-catenin was significantly more frequent in intestinal-type (P =.0049) and well-differentiated gastric cancers (P <.001). There were no quantitative differences between gastric cancers and the nonmalignant gastric tissues, as determined by Western blot analysis. One of 18 metastatic cancer lesions and four of five gastric cancer cell lines expressed beta-catenin protein. N87 cells, derived from the liver metastasis of a gastric cancer, did not express beta-catenin. Treatment with 5'-azadeoxycytidine restored beta-catenin protein levels in this cell line, which exhibited significantly more 5-methylcytosines in the beta-catenin promoter compared with the other cell lines. CONCLUSION: beta-Catenin expression is lost in a subgroup of primary gastric cancers, is frequently absent in metastases, and exhibits nuclear localization in cancers with either beta-catenin or APC gene mutations. Interestingly, the loss of beta-catenin expression in metastatic gastric cancers may result from hypermethylation of the beta-catenin promoter.  相似文献   
70.
Background: The presence in bone marrow of cells which react with monoclonal antibodies against tumor-associated antigens has been proposed over the last few years as a new prognostic factor in breast cancer patients. Patients and methods: Bone marrow aspirates were obtained from 109 stage I and II breast cancer patients during or 2–4 weeks after primary surgery. The samples were processed for leukocyte separation on a Ficoll-Hypaque gradient and then used to prepare cytospin slides for immunocytochemical analysis. The slides were stained with a pool of monoclonal antibodies (MoAbs) which recognize tumor associated antigens, using the alkaline phosphatase anti-alkaline phosphatase method. The median follow-up was 36 months (range 15–62); 22 patients relapsed and 7 died. Results: Thirty-four of the 109 patients (31.1%) had MoAb positive bone marrow cells. The bone marrow was positive in 28/74 (37.9%) patients who had the aspirate taken during surgery and in 6/35 (17.1%) who had it taken after surgery (p = 0.055). No association was found between bone marrow positivity and tumour size, nodal status, menopausal status, estrogen receptor positivity or the proliferative index. No association was found between bone marrow and prognosis: the log-rank test was 0.291 (p > 0.5) for OS and 0.023 for DFS; the hazard ratio (positive vs negative) was 1.51 for OS (95% CI: 0.33–6.86) and 0.93 for DFS (95% CI: 0.35–2.45). Conclusions: In our series, bone marrow positivity did not correlate with prognostic parameters or prognosis. Of interest is the relative excess of positivity when the bone marrow was obtained during surgery.  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