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   71749篇
  免费   4846篇
  国内免费   201篇
耳鼻咽喉   529篇
儿科学   2091篇
妇产科学   1166篇
基础医学   9832篇
口腔科学   1505篇
临床医学   7523篇
内科学   15209篇
皮肤病学   981篇
神经病学   6823篇
特种医学   2227篇
外国民族医学   1篇
外科学   10043篇
综合类   878篇
一般理论   72篇
预防医学   6392篇
眼科学   1737篇
药学   4906篇
  1篇
中国医学   80篇
肿瘤学   4800篇
  2023年   376篇
  2022年   521篇
  2021年   1397篇
  2020年   839篇
  2019年   1364篇
  2018年   1659篇
  2017年   1237篇
  2016年   1356篇
  2015年   1582篇
  2014年   2366篇
  2013年   3210篇
  2012年   5236篇
  2011年   5367篇
  2010年   3001篇
  2009年   2666篇
  2008年   4873篇
  2007年   5332篇
  2006年   5237篇
  2005年   4969篇
  2004年   4765篇
  2003年   4309篇
  2002年   4204篇
  2001年   573篇
  2000年   403篇
  1999年   634篇
  1998年   899篇
  1997年   754篇
  1996年   634篇
  1995年   605篇
  1994年   490篇
  1993年   464篇
  1992年   347篇
  1991年   304篇
  1990年   256篇
  1989年   246篇
  1988年   261篇
  1987年   213篇
  1986年   231篇
  1985年   240篇
  1984年   308篇
  1983年   324篇
  1982年   384篇
  1981年   369篇
  1980年   343篇
  1979年   197篇
  1978年   239篇
  1977年   191篇
  1976年   133篇
  1975年   102篇
  1974年   105篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Ziprasidone is an atypical antipsychotic with a unique receptor-binding profile. Currently, ziprasidone is approved by the US Food and Drug Administration for the acute treatment of psychosis in schizophrenia and mania in bipolar disorder. When compared to certain other atypical antipsychotics, ziprasidone appears to have a relatively benign side effect profile, especially as regards metabolic effects eg, weight gain, serum lipid elevations and glucose dysregulation. Taken together, these data suggest that ziprasidone may be a first line treatment for patients with bipolar mania. However, ziprasidone is a relatively new medication for which adverse events after long-term use and/or in vulnerable patient populations must be studied. Unstudied areas of particular importance include the efficacy and safety of ziprasidone in the treatment of bipolar depression and relapse prevention of mania as, well as in the subpopulations of pregnant women, the elderly and pediatric patients. The emergence of mania in patients taking ziprasidone is another topic for further study.  相似文献   
102.
103.
The use of laparoscopic surgical techniques is now being applied to a variety of operations traditionally performed in an open fashion. Twenty patients underwent laparoscopic-guided large and small bowel surgery at our institution from March 1991 to April 1992. The indications for surgery included polyps, obstruction, bleeding, and perforation, and pathologic diagnoses included benign polyps, lipomas, inflammatory bowel disease, perforation of a jejunal diverticulum, colonic arteriovenous malformations, and adenocarcinoma. Mobilization of the colon, ligation of the mesentery, and closure of the mesenteric defect were performed using the laparoscopic equipment. One trocar site was enlarged to 3 cm to deliver the bowel through the abdominal wall. All anastomoses were hand-sewn. Postoperative hospitalization ranged from 2 to 31 days (median, five days). No mortality was noted, and morbidity was 20 percent. We conclude that laparoscopic-guided bowel surgery is technically feasible and should translate into shorter hospitalization and less patient discomfort.  相似文献   
104.
This study investigated a discrete-trial, titration duration discrimination procedure in behavioral pharmacology. Pentobarbital and d-amphetamine, measured with this procedure, selectively affected discrimination more than response tendencies. Pentobarbital also tended to affect selectively discrimination of longer durations, whereas d-amphetamine did not. Further experiments showed that (1) other algorithms for modulating stimulus duration are useful in behavioral pharmacology and toxicology, (2) threshold estimates are similar with the method of constant stimuli and the method of titration, and (3) this titration procedure permits the separate examination of drug effects upon discrimination and upon response tendencies; the fixed-interval procedure does not. Baseline variability was an important correlate of drug effects in that the endpoints with more variable baselines were also more sensitive to drugs.  相似文献   
105.
The visit of Dr. Trendley Dean to Dublin in the mid-1950s helped accelerate the decision to introduce water fluoridation as a public health measure in the prevention of caries in the Republic of Ireland. A challenge to the constitutional validity of the Health (Fluoridation of Water Supplies) Act 1960 failed and in 1964 the water supplies of Dublin city were fluoridated. Over the next seven to eight years all the major urban communities in the Republic of Ireland were fluoridated. Currently, 67 percent of the 3.5 million people in the country reside in fluoridated communities. Studies conducted over the last 20 years show that residents of fluoridated communities have better dental health than those in nonfluoridated communities—the mean dmft is lower in children and the number of natural teeth present in adults is higher.  相似文献   
106.
Lewis Histo-Blood Group System and Associated Secretory Phenotypes   总被引:6,自引:0,他引:6  
This review summarises present knowledge of the chemistry, immunology, genetics and clinical significance of antibodies in the Lewis and secretor histoblood group systems. Although red cell serology has laid the foundations for these systems, more recent advances have been made by studying Lewis and related glycoconjugates with monoclonal antibodies, determining structures by mass spectrometry and NMR spectroscopy, identifying enzymes and their specificities, and identifying the genes by molecular biology. The expression of Lewis system antigens is dependent on Lewis and secretor loci. Fucosyltransferases coded by genes at these loci compete and interact with each other and with other transferases to determine an individual's Lewis and secretor phenotype. Exocrine epithelial cells, mostly of endodermal origin, synthesise the Lewis antigens which, as plasma glycolipids, are secondarily acquired by cells of the peripheral circulation. Phenotyping red cells is often regarded as a simple way of determining the Lewis and sometimes the secretor status of an individual; however, the red cell phenotype is influenced by many factors and may not necessarily reflect someone's Lewis and secretor genotypes. Two main red cell Lewis groups are usually found, Lewis negative and Lewis positive. In Lewis-negative individuals, the secretor genotype does not affect the Lewis phenotype, but in Lewis-positive individuals, the non-secretor genotype generates the Le(a+b–) phenotype, the secretor genotype causes the Le(a–b+) phenotype, and the partial secretor genotype gives rise to the Le(a+b+) phenotype.  相似文献   
107.
This study examined the mitogenic response to keratinocyte growth factor (KGF) of normal and tumour-derived human oral keratinocytes in which the degree of cellular differentiation was known and in contiguous fibroblast cultures derived from the malignant epithelial cultures. Keratinocytes, but not fibroblasts, were stimulated by KGF. There by demonstrating epithelial target cell specificity of the ligand. KGF-induced stimulation of the tumour-derived keratinocytes cultured in the absence of the 3T3 fibroblast support broadly correlated with the degree of cellular differentiation; well-differentiated keratinocytes were stimulated more by KGF than their less differentiated counterparts. Malignant oral keratinocytes expressed KGF cell surface receptors (KD 451-709 pM; receptors/cell 2306-413645), but KGF receptor mRNA did not correlate with either KGF-induced mitogenesis or the degree of epithelial cell differentiation. When the tumour-derived keratinocytes were cultured in the presence of 3T3 fibroblasts, the mitogenic response to KGF was comparable to normal epithelial cells. The results suggest that KGF-mediated growth stimulation may not be significant in providing a selective advantage for the growth of malignant keratinocytes.  相似文献   
108.
109.
A partnership between corporate worksites, a community-based prevention agency, and families in those worksites is described. Its primary goals were the reduction of family risk and enhancement of family protective factors that predispose children and youth to substance abuse and related social and emotional difficulties. A related goal of the program is to reduce family stress levels and attitudes that may influence the parents' levels of risk for substance abuse and related disorder. The program delivery strategy is conceived of as part of the necessart efforts of prevention programs to reach target populations in host settings in which they may naturally participate, thereby reducing obstacles and barriers to participation that often impede prevention efforts. Evaluation revealed that the program was generally better able to retain parents for a fairly lengthy period, and with high rates of attendance. Program attendance was also not affected by parental background characteristics that, in other delivery approaches, are often associated with poor attendance and high drop-out levels. Results also indicated that levels of program exposure (dosage) do make a significant difference in the efficacy of such efforts as those parents in the program who participated in higher percentages and numbers of sessions (i.e. more than 80% of sessions) showed both short-term and longer-term (i.e. across 18 month follow-ups) gains in their ratings of the target child's behavior problems and strengths, substance abuse resistance related knowledge and attitudes, reduced parental stress, depression and irritability, and increased utilization of social support. By contrast, parents who received a low program exposure exhibited a more restricted set of short-term gains. The findings are discussed in terms of their importance for consideration of program dosage for prevention programs, and the need to attend to the context in which programming is offered as it may facilitate or impede efforts to provide levels of dosage and fidelity to create enduring impacts  相似文献   
110.
In order to determine whether a specialist psychogeriatric nursing home was fulfilling its intended role of caring for the most behaviourally disturbed dementia sufferers, 24 of its demented residents were compared with 28 demented individuals discharged from a psychiatric unit to ordinary nursing homes and 30 mobile dementia sufferers in nursing home wards of a geriatric centre. Those in the psychogeriatric nursing home showed more disturbed behaviours than those in the other two settings. Scores on the Rating Scale for Aggressive Behaviour in the Elderly were compared with degree of cognitive impairment for the first time in the literature and showed no correlation with degree of cognitive impairment for the first time in the literature and showed no correlation with congnitive performance.  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