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   63313篇
  免费   4584篇
  国内免费   334篇
耳鼻咽喉   635篇
儿科学   1602篇
妇产科学   1539篇
基础医学   7843篇
口腔科学   1537篇
临床医学   6357篇
内科学   14384篇
皮肤病学   809篇
神经病学   4999篇
特种医学   1916篇
外国民族医学   2篇
外科学   9740篇
综合类   1010篇
现状与发展   1篇
一般理论   103篇
预防医学   5253篇
眼科学   1859篇
药学   4428篇
中国医学   139篇
肿瘤学   4075篇
  2023年   292篇
  2022年   463篇
  2021年   1156篇
  2020年   724篇
  2019年   1011篇
  2018年   1244篇
  2017年   847篇
  2016年   968篇
  2015年   1136篇
  2014年   1774篇
  2013年   2809篇
  2012年   3774篇
  2011年   4115篇
  2010年   2346篇
  2009年   2191篇
  2008年   4009篇
  2007年   4192篇
  2006年   4020篇
  2005年   4114篇
  2004年   3842篇
  2003年   3454篇
  2002年   3415篇
  2001年   730篇
  2000年   623篇
  1999年   722篇
  1998年   741篇
  1997年   609篇
  1996年   492篇
  1995年   491篇
  1994年   466篇
  1993年   440篇
  1992年   531篇
  1991年   509篇
  1990年   417篇
  1989年   438篇
  1988年   396篇
  1987年   373篇
  1986年   355篇
  1985年   419篇
  1984年   432篇
  1983年   394篇
  1982年   528篇
  1981年   443篇
  1980年   485篇
  1979年   301篇
  1978年   321篇
  1977年   321篇
  1976年   261篇
  1975年   287篇
  1974年   246篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Comparing Crow's schizophrenia model with the defect state and Huber's basic symptoms shows that this model is an oversimplification of the complex reality of schizophrenic outcomes. The concept of negative symptoms is undermined by several factors, such as differing definitions, other confounding cross-sectional variables (e.g., akinesia and depression), short follow-ups and lack of confirmation by factorial analysis. The longitudinal concept of a defect state, which has been used in long-term follow-up studies, includes enduring symptoms currently classified as positive and negative. Huber's conceptualization of basic symptoms describes prodromal and enduring residual symptoms of schizophrenia associated with structural brain abnormalities. The overlap and lack of equivalence of these concepts and the limited empirical evidence does not allow firm conclusions. New longitudinal studies using clinical, psychosocial, and neuropsychological measures are needed to understand the natural history and etiology of the defect state.The authors are affiliated with the Medical College of Pennsylvania/EPPI, Philadelphia, PA. William H. Wilson, M.D., is currently at Oregon Health Sciences University, Portland, OR.  相似文献   
82.
Performance of same-day upper and lower endoscopy has many potential advantages, as it may reduce costs, shorten hospital stay, and expedite patient care, but its feasibility, efficacy, and potential have not been carefully defined. We report here our experience with a group of 87 patients who underwent same-day upper and lower endoscopy (174 procedures) over a 2-yr period at a tertiary care VA Hospital, compared with an alternate-day upper and lower endoscopy group of 50 patients (100 procedures) over the same time period. Most patients were elderly males. Common indications for endoscopy were occult or overt gastrointestinal bleeding, previous or concomitant history of pertinent pathology (i.e., polyps, ulcers), abdominal pain, diarrhea, or other symptoms, abnormal radiological studies, and iron deficiency anemia. Both groups required similar amounts of intravenous sedation. There were no complications in either group. In both groups, common positive findings were inflammation (i.e., colitis, esophagitis), benign neoplasms, diverticulae, peptic ulcer, and cancer. In both groups, only 2-6% had negative upper and lower endoscopy, whereas either one procedure was negative in 25% and 18% of cases, respectively. We conclude that the practice of same-day inpatient upper and lower endoscopy is feasible, has excellent diagnostic yield, even in the elderly, and carries no increased risks. When indicated, the practice of same-day upper and lower endoscopy should be encouraged.  相似文献   
83.
84.
Psychophysical functions are used to characterize both normal perception and altered perception among patients with neglect, yet the reliability of these functions is rarely examined. The present study examined two-week, test-retest reliability for power functions derived from line bisection data among 58 normal, young and old, male and female subjects. Power function exponents and constants were, at best, moderately reliable over time. The size of the exponent tended to decrease at retesting. Reliability coefficients varied by age and gender; they were highly significant for young men, marginally significant for older men, and non-significant for women. Race influenced reliability as coefficients were significant for Caucasian subjects but not for African American subjects. Age and gender effects in this study parallel those in the literature on pseudoneglect, and they may reflect hemispheric differences in visuo-spatial processing, magnitude estimation, or both.  相似文献   
85.
The Arden Syntax for sharing medical knowledge bases is described. Its current focus is on knowledge that is represented as a set of independent modules that can provide therapeutic suggestions, alerts, diagnosis scores, etc. The syntax is based largely upon HELP and the Regenstrief Medical Record System. Each module, called a Medical Logic Module or MLM, is made of slots grouped into maintenance, library, and knowledge categories. The syntax has provisions for querying a clinical database and representing time. Several clinical information systems were analyzed and appear to be compatible with the syntax. The syntax has been tested for syntactic ambiguities using the tools lex and yacc. Seventeen institutions are currently in the process of adopting the Arden Syntax for their decision-support systems. A subcommittee of ASTM has been formed to develop standards for sharing medical knowledge bases. The Arden Syntax has been published by ASTM as a initial standard for sharing medical knowledge.  相似文献   
86.
87.
The standard treatment for patients with advanced ovarian cancer (AOC) has been cyclophosphamide and cisplatin (CP). Recently, the results of a large randomized comparative trial demonstrated that the combination of paclitaxel and cisplatin (TP) provided a progression-free survival benefit of 5 months. In this study, a cost–utility analysis was performed from a Canadian health care system perspective to estimate the incremental cost-effectiveness of the TP combination. Twelve AOC patients who received treatment with TP were matched for age and disease stage on a 1-to-2 basis with a CP control. Total hospital resource consumption was then collected for all patients. Treatment preferences were estimated from a cohort of 20 patients and 40 healthy female volunteers using the time trade-off technique. The outcomes were then generated through a decision-analytic model. First-line treatment costs with TP were approximately fourfold greater on a per-cycle basis than the CP alternative (Can$1911 vs Can$459). When progression-free survival benefit and patient treatment preferences were incorporated into the analysis, the results of the decision model revealed an incremental cost between Can$12,000 and Can$24,000 per quality-adjusted progression-free year with the TP protocol. Even though the TP combination has a considerably higher drug acquisition cost, the results of the current analysis suggest that this new chemotherapy regimen does provide patients with substantial quality-adjusted progression-free survival benefit at a reasonable cost to the Canadian health care system.  相似文献   
88.
Intraoperative radiation therapy (IORT) research is limited by the lack of small-animal models. We have implanted B16 melanoma into mouse kidneys, which we subsequently operated upon and irradiated with beta rays from a 90Sr ophthalmic applicator. The IORT has effectively prolonged survival and produced some cures. The strategy should be applicable to other murine tumors and to other internal implantation sites.  相似文献   
89.
A new look at grief   总被引:1,自引:0,他引:1  
  相似文献   
90.
In a population-based longitudinal cohort study, we tested the hypothesis that children growing up in a high-traffic polluted urban area (UA) in the Athens' basin have higher prevalence of allergies and sensitization when compared with those growing up in a Greek provincial rural area (RA). We recruited 478 and 342 children aged 8-10 living in the UA and the RA, respectively. Respiratory health was assessed by a parent-completed questionnaire in three phases: 1995-96 (phase 1), 1999-2000 (phase 2), 2003-04 (phase 3) and skin-prick testing to common indoor and outdoor aeroallergens was performed at phases 1 and 2. Reported asthma and eczema did not differ between the two areas, whereas reported hay fever was persistently more prevalent in the UA than in the RA (16.5%, 17.0%, 18.2% vs. 7.0%, 8.3%, 9.6%, respectively). Sensitization was more prevalent in the UA at both phases (19.0% vs. 12.1% in phase 1, 20.0% vs. 14.1% in phase 2). Residential area contributed independently to sensitization to >or=1 aeroallergens (OR: 0.29; 95% CI: 0.13-0.66; p = 0.003) and to polysensitization (OR: 0.28; 95% CI: 0.10-0.82; p = 0.020) in phase 1. These associations were independent of farming practices. No significant contributions were found in phase 2. Our results suggest that long-term exposure to urban environment is associated with a higher prevalence of hay fever but not of asthma or eczema. The negative association between rural living and the risk of atopy during childhood, which is independent of farming practices, implies that it is mainly driven by an urban living effect.  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