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   16823篇
  免费   1197篇
  国内免费   59篇
耳鼻咽喉   307篇
儿科学   451篇
妇产科学   411篇
基础医学   2524篇
口腔科学   446篇
临床医学   1705篇
内科学   3450篇
皮肤病学   296篇
神经病学   1445篇
特种医学   648篇
外国民族医学   1篇
外科学   2306篇
综合类   209篇
一般理论   50篇
预防医学   1389篇
眼科学   419篇
药学   1112篇
中国医学   19篇
肿瘤学   891篇
  2023年   63篇
  2022年   98篇
  2021年   297篇
  2020年   143篇
  2019年   269篇
  2018年   324篇
  2017年   252篇
  2016年   279篇
  2015年   312篇
  2014年   426篇
  2013年   793篇
  2012年   921篇
  2011年   1089篇
  2010年   588篇
  2009年   508篇
  2008年   918篇
  2007年   979篇
  2006年   901篇
  2005年   914篇
  2004年   939篇
  2003年   861篇
  2002年   917篇
  2001年   188篇
  2000年   145篇
  1999年   176篇
  1998年   236篇
  1997年   194篇
  1996年   177篇
  1995年   158篇
  1994年   158篇
  1993年   136篇
  1992年   105篇
  1991年   95篇
  1990年   92篇
  1989年   102篇
  1988年   95篇
  1987年   99篇
  1986年   83篇
  1985年   100篇
  1984年   120篇
  1983年   93篇
  1982年   162篇
  1981年   129篇
  1980年   134篇
  1979年   81篇
  1978年   90篇
  1977年   78篇
  1976年   74篇
  1974年   78篇
  1973年   64篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Purpose: Using peripheral venous pressure (PVP) instead of central venous pressure (CVP) as a volume monitor decreases patient risks and costs, and is convenient. This study was undertaken to determine if PVP predicts CVP in pediatric patients. METHODS: With ethical approval and informed consent, 30 pediatric patients aged neonate to 12 yr requiring a central venous line were studied prospectively in a tertiary care teaching hospital. In the supine position, PVP and CVP were simultaneously transduced. Ninety-six paired recordings of CVP and PVP were made. Correlation and Bland-Altman analysis of agreement of end-expiratory measurements were performed. RESULTS: The mean (SD; range) CVP was 10.0 mmHg (6.0; -1.0 to 27.0); the mean PVP was 13.7 mmHg (6.3; 0.0 to 33.0); offset (bias) of PVP > CVP was 3.7 mmHg with SD 2.6. The 95% confidence intervals (CI) for the bias were 3.2 to 4.1 mmHg. In the Bland-Altman analysis, lower and upper limits of agreement (LOA; CI in parentheses) were -1.5 (-2.3 to -0.7) and 8.8 (8.1 to 9.6) mmHg. Eight of 96 points were outside the limits of agreement. The correlation of PVP on CVP was r = 0.92, P < 0.0001. For a subset of ten patients (20 simultaneous recordings) with iv catheters proximal to the hand, limits of agreement were better - offset: 3.8 mmHg (+/- 1.4); lower LOA: 1.2 mmHg (0.25 to 2.1); upper LOA: 6.6 mmHg (5.7 to 7.5). CONCLUSION: Peripheral venous pressure measured from an iv catheter in the hand predicts CVP poorly in pediatric patients.  相似文献   
62.
Rotigotine is a new, non-ergot dopamine agonist formulated in a transdermal delivery system. The present study was to investigate the efficacy and safety of the rotigotine transdermal patch in the treatment of early Parkinson's disease. Patients (n = 561) were randomized to rotigotine, ropinirole, or placebo. The titration period was up to 13 weeks, and there was a minimum dose-maintenance period of 24 weeks for ropinirole and 33 weeks for rotigotine. The primary endpoint was the proportion of patients with a minimum of 20% decrease in the combined Unified Parkinson's Disease Rating Scale Part II and Part III scores. The responder rate in the rotigotine group was significantly higher than in the placebo group (52% vs. 30%, P < 0.0001). Transdermal rotigotine at doses < or =8 mg/24 h did not show noninferiority to ropinirole at doses < or =24 mg/day. In a post-hoc subgroup analysis, rotigotine < or =8 mg/24 hours had a similar efficacy to ropinirole at doses < or =12 mg/day. The rotigotine transdermal patch was well tolerated. The most common adverse events were application-site reactions, nausea, and somnolence. Application-site reactions were predominantly mild or moderate in intensity. In conclusion, the rotigotine transdermal patch represents an effective and safe option for the treatment of patients with early Parkinson's disease.  相似文献   
63.
64.
PURPOSE: The presence of similar histologic subtypes of epithelial ovarian and endometrial cancers has long been noted, although the relevance of this finding to pathogenesis and clinical management is unclear. Despite similar clinical characteristics, histologic subtypes of cancers of the ovary and endometrium are treated according to organ of origin. This study compares the gene expression profiles of analogous histologic subtypes of cancers of the ovary and endometrium using the same genomic platform to determine the similarities and differences between these tumors. EXPERIMENTAL DESIGN: Gene expression profiles of 75 cancers (endometrioid, serous, and clear cell) of the ovary and endometrium, five renal clear cell cancers, and seven normal epithelial brushings were determined using a 11,000-element cDNA array. All images were analyzed using BRB ArrayTools. Validation was done using real-time PCR on select genes and immunohistochemical staining. RESULTS: Comparison across endometrial and ovarian cancers and serous and endometrioid tumors showed expression patterns reflecting their organ of origin. Clear cell tumors, however, showed remarkably similar expression patterns regardless of their origin, even when compared with renal clear cell samples. A set of 43 genes was common to comparisons of each of the three histologic subtypes of ovarian cancer with normal ovarian surface epithelium. CONCLUSIONS: The comparison of the gene expression profiles of endometrioid and serous subtypes of ovarian and endometrial cancer are largely unique to the combination of a particular subtype in a specific organ. In contrast, clear cell cancers show a remarkable similarity in gene expression profiles across organs (including kidney) and could not be statistically distinguished.  相似文献   
65.
66.
The calcifying epithelial odontogenic tumor (CEOT), or Pindborg tumor, is a rare and benign odontogenic neoplasm that affects the jaw. The most common manifestation of CEOT is a unifocal or localized lesion of the involved jaw, which may appear clinically as a hard tissue swelling and radiographically as a mixed radiolucent-radiopaque mass. In this article, we present a unique case of CEOT affecting multiple sites in the maxilla and mandible of a 51-year-old white man. Though biopsy samples from all involved sites revealed similar histopathologic features consistent with CEOT, the fact that there was a multifocal presentation is an unusual phenomenon for CEOT and has never been reported. Multifocal odontogenic lesions are not typical but have been observed in conditions associated with known genetic mutations. For example, multiple odontogenic keratocysts are the most common feature of the inherited condition known as nevoid basal cell carcinoma syndrome. This case, however, is the first one to demonstrate that there may be a multifocal variant of CEOT that has not been previously recognized.  相似文献   
67.
RATIONALE: Holocaust survivors, who experienced trauma 60 years ago, provide an opportunity to explore the impact of early lifetime trauma in later life and, in particular, the interplay of depression and posttraumatic stress disorder (PTSD). In this study, the authors contrast depressed Holocaust survivors (HD), nondepressed Holocaust survivors (HND), and older depressed persons (CD). METHODS: The sample consisted of 36 consecutive Holocaust survivors (mean age: 79 years) treated in a primary care practice, among whom 20 (56%) were diagnosed as having a major depressive disorder and 16 as nondepressed; 18 depressed non-Holocaust Jewish primary care patients served as controls (mean age: 84 years). The authors examined nine clinical and social variables. The Kruskal-Wallis, Mann-Whitney U, and chi(2) tests were used to contrast the groups. The authors used a conservative significance level of .01. RESULTS: In contrast to the CD group, the HD group was significantly older, more likely to report PTSD and guilt symptoms, to have higher Beck Anxiety Inventory (BAI) and Brief Psychiatric Rating Scale (BPRS) scores, and to have more impaired social functioning. In contrast to the HND group, the HD group was significantly more likely to report PTSD and guilt feelings, to have higher Hamilton Depression Scale (HAM-D), BAI, and BPRS scores, and to have more impaired social functioning. In contrast to the CD group, the HND group was significantly more likely to have PTSD symptoms and to have lower HAM-D and BPRS scores. CONCLUSIONS: The prevalence of depression and PTSD symptoms were very high among survivors. Depressed survivors had significantly worse psychologic and social functioning than depressed controls. Depressed survivors had more PTSD symptoms than nondepressed survivors, although it is unclear as to the causal direction of the relationship between depression and PTSD.  相似文献   
68.
69.
On May 8–10, 1995, a workshop on chronic inhalation toxicity and carcinogenicity testing of respirable fibrous particles was held in Chapel Hill, North Carolina. The workshop was sponsored by the Office of Pollution Prevention and Toxics, U.S. Environmental Protection Agency (EPA), in collaboration with the National Institute of Environmental Health Sciences (NIEHS), the National Institute for Occupational Safety and Health (NIOSH), and the Occupational Safety and Health Administration (OSHA). The goal of the workshop was to obtain input from the scientific community on a number of issues related to fiber testing. Major issues for discussion were: (i) the optimal design and conduct of studies of the health effects of chronic inhalation exposure of animals to fibers; (ii) preliminary studies which would be useful guides in designing the chronic exposure study; (iii) mechanistic studies which would be important adjuncts to the chronic exposure study to enable better interpretation of study results and extrapolation of potential effects in exposed humans; and (iv) available screening tests which can be used to develop a minimum data set for (a) making decisions about the potential health hazard of the fibers and (b) prioritizing the need for further testing in a chronic inhalation study. After extensive discussion and debate of the workshop issues, the general consensus of the expert panel is that chronic inhalation studies of fibers in the rat are the most appropriate tests for predicting inhalation hazard and risk of fibers to humans. A number of guidances specific for the design and conduct of prechronic and chronic inhalation studies of fibers in rodents were recommended. For instance, it was recommended that along with other information (decrease in body weight, systemic toxicity, etc.), data should be obtained on lung burdens and bronchoalveolar lavage fluid analysis to assist in establishing the chronic exposure levels. Lung burden data are also important for quantifying aspects of risk assessment related to dosimetric adjustments before extrapolation. Although mechanistic studies are not recommended as part of the standard chronic inhalation studies, the expert panel stressed the need for obtaining mechanistic information as far as possible during the course of subchronic or chronic inhalation studies. At present, no single assay and battery of short-term assays can predict the outcome of a chronic inhalation bioassay with respect to carcinogenic effects. Meanwhile, several short-termin vitroandin vivostudies that may be useful to assess the relative potential of fibrous substances to cause lung toxicity/carcinogenicity have been identified.  相似文献   
70.
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