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   27099篇
  免费   2244篇
  国内免费   44篇
耳鼻咽喉   251篇
儿科学   1068篇
妇产科学   771篇
基础医学   3647篇
口腔科学   409篇
临床医学   3729篇
内科学   4685篇
皮肤病学   285篇
神经病学   2612篇
特种医学   734篇
外国民族医学   1篇
外科学   2542篇
综合类   880篇
一般理论   66篇
预防医学   3528篇
眼科学   530篇
药学   1713篇
中国医学   12篇
肿瘤学   1924篇
  2023年   111篇
  2022年   181篇
  2021年   402篇
  2020年   297篇
  2019年   429篇
  2018年   455篇
  2017年   379篇
  2016年   427篇
  2015年   528篇
  2014年   693篇
  2013年   1110篇
  2012年   1557篇
  2011年   1627篇
  2010年   817篇
  2009年   754篇
  2008年   1449篇
  2007年   1603篇
  2006年   1552篇
  2005年   1537篇
  2004年   1563篇
  2003年   1474篇
  2002年   1453篇
  2001年   518篇
  2000年   485篇
  1999年   476篇
  1998年   342篇
  1997年   301篇
  1996年   325篇
  1995年   276篇
  1994年   245篇
  1993年   247篇
  1992年   372篇
  1991年   374篇
  1990年   366篇
  1989年   358篇
  1988年   318篇
  1987年   315篇
  1986年   305篇
  1985年   282篇
  1984年   255篇
  1983年   271篇
  1982年   187篇
  1981年   182篇
  1980年   154篇
  1979年   241篇
  1978年   170篇
  1977年   138篇
  1976年   148篇
  1974年   131篇
  1972年   117篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
Potential digestibility and rate of degradation of water-insoluble material (WIM) prepared from rutabaga, wheat bran and digesta recovered from the terminal ileum of pigs fed bran- or rutabaga-based diets were measured in the cecum of surgically modified pigs. WIM samples recovered from the cecum after fixed incubation times were analyzed and the rate of total disappearance of organic matter, cellulose, uronic acid and noncellulosic neutral sugars was calculated. Maximum degradation of each WIM occurred within 48 h after incubation and was for rutabaga and its ileal digesta 90 and 70%, respectively, and for bran and bran ileal digesta 55 and 45%, respectively. Cellulose and uronic acid in bran samples did not appear to be degraded, material disappearance being attributable to the loss of noncellulosic neutral sugars. Estimation of potential organic matter digestibility showed rutabaga to be 93%, rutabaga digesta 79%, bran 56% and bran digesta 43% digestible. Fractional rates of digestion in rutabaga samples were significantly faster than in corresponding bran samples. When related to the role of fiber in nutrition the results obtained suggest that cereal fiber would be only slightly modified during gut transit, unlike vegetable fiber in which microbial digestion would probably result in the total destruction of the fiber cell wall matrix.  相似文献   
33.
We examined several possible causes for the high incidence of poor sensory acuity in the limbs of 176 patients with moderate to severe peripheral vascular insufficiency. We investigated the relationships of diabetes, alcoholism, and smoking, as well as the severity of peripheral vascular disease, to the integrity of basic sensory modalities such as two-point discrimination and perception of light touch. The presence or absence of diabetes exerted the strongest effect on peripheral sensation. In patients who did not have diabetes, sensation in the limbs was most strongly affected by whether the patient was an alcoholic. Smoking did not have a significant effect on limb sensation. Among nondiabetic, nonalcoholic patients, there was a weak residual effect related to the severity of the peripheral vascular insufficiency. Even among these patients, however, systemic factors predominated in determining the loss of sensation. We also examined the extent to which loss of sensation might be related to the development of ulcers. Among patients who were not diabetic, there was a highly significant relationship between loss of sensation and the presence of limb ulceration. Surprisingly, however, there was no discernable relationship between the presence of ulcers in diabetic patients and the degree of loss of peripheral sensation. This result suggests that a large percentage of ulcers seen in diabetic patients are not of neurogenic origin.  相似文献   
34.
PURPOSE: Epidermal growth factor receptor is expressed in pediatric malignant solid tumors. We conducted a phase I trial of gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, in children with refractory solid tumors. PATIENTS AND METHODS: Gefitinib (150, 300, 400, or 500 mg/m2) was administered orally to cohorts of three to six patients once daily continuously until disease progression or significant toxicity. Pharmacokinetic studies were performed during course one (day 1 through 28). RESULTS: Of the 25 enrolled patients, 19 (median age, 15 years) were fully evaluable for toxicity and received 54 courses. Dose-limiting toxicity was rash in two patients treated with 500 mg/m2 and elevated ALT and AST in one patient treated with 400 mg/m2. The maximum-tolerated dose was 400 mg/m2/d. The most frequent non-dose-limiting toxicities were grade 1 or 2 dry skin, anemia, diarrhea, nausea, and vomiting. One patient with Ewing's sarcoma had a partial response. Disease stabilized for 8 to > or = 60 weeks in two patients with Wilms' tumor and two with brainstem glioma (one exophytic). At 400 mg/m2, the median peak gefitinib plasma concentration was 2.2 microg/mL (range, 1.2 to 3.6 microg/mL) and occurred at a median of 2.3 hours (range, 2.0 to 8.3 hours) after drug administration. The median apparent clearance and median half-life were 14.8 L/h/m2 (range, 3.8 to 24.8 L/h/m2) and 11.7 hours (range, 5.6 to 22.8 hours), respectively. Gefitinib systemic exposures were comparable with those associated with antitumor activity in adults. CONCLUSION: Oral gefitinib is well tolerated in children. Development of the drug in combination with cytotoxic chemotherapy will be pursued.  相似文献   
35.
36.

Background  

Health service policy in the United Kingdom emphasises the importance of self-care by patients with chronic conditions. Written information for patients about their condition is seen as an important aid to help patients look after themselves. From a discourse analysis perspective written texts such as patient information leaflets do not simply describe the reality of a medical condition and its management but by drawing on some sorts of knowledge and evidence rather than others help construct the reality of that condition. This study explored patient information leaflets on osteoarthritis (OA) to see how OA was constructed and to consider the implications for self-care.  相似文献   
37.
Objectives: Heavy smokers are a segment of the smoking population who are at increased risk of smoking-related morbidity and least likely to achieve cessation. This study identifies the impact of heavy smoking on quality of life by gender and describes the subpopulation for improved targeting.Methods: South Australian representative population data (n = 3010) was used to compare the health-related quality of life status of male and female heavy smokers as assessed by the SF-36.  相似文献   
38.
BACKGROUND: Methamphetamine abuse has become a major public health problem as demonstrated by increases in the number of emergency room visits, substance abuse treatment episodes, and arrests attributable to methamphetamine manufacture and abuse. We examine the effectiveness of conventional substance abuse treatment in the recovery of individuals seeking voluntary treatment for methamphetamine abuse. METHODS: At the request of the Iowa Department of Public Health, the Iowa Consortium for Substance Abuse Research and Evaluation contacted clients who had been admitted to voluntary treatment for methamphetamine abuse. Staff from the Consortium asked subjects to volunteer for follow-up interviews at designated intervals following admission. Agency staff conducted interviews based on the Mini International Neuropsychiatric Interview (MINI) at admission and at designated intervals and reported results to the Consortium for analysis. RESULTS: Subjects were predominantly Caucasian and over one half were female with an average age of 30 years. The criminal justice system was a primary referral source. Reported psychiatric symptoms dropped substantially in the first 60 days following admission and appeared to remain low at 6 and 12 months. Most clients reported abstinence and employment and denied arrests at the 6-month interview. Outcomes were not correlated with psychiatric symptoms. CONCLUSIONS: Psychiatric symptoms improved over time with usual substance abuse treatment. There was no evidence that referral by the court system or symptoms of antisocial personality disorder affected outcome. Conventional treatment resulted in sobriety, employment, and fewer arrests at 6 and 12 months following treatment.  相似文献   
39.
This article reports the results of semi-structured interviews with substance abuse treatment (SAT) program directors (PDs) regarding the ways SAT is being influenced by managed care (MC), plans for future SAT, and strategies for decreasing costs of care. It compares findings to an earlier survey of 50 SAT PDs.

Interviews were conducted in 20 SAT programs to gather information about treatment delivery since the advent of MC, including PD responsibilities, funding source, treatment intensity, location, duration, and methods of treatment. Open-ended responses were used to gather information about current and future plans in providing SAT, and awareness of new types of treatment being planned by organizations impacted by MC.

PDs reported changes in SAT secondary to MC such as decreased treatment length, limiting of inpatient and outpatient services, and delayed treatment secondary to benefit determination. Political and economic constraints were seen as barriers to providing adequate and effective services. SAT being subsumed by mental health was viewed as problematic along with an emerging split between alcohol abuse and drug treatment. A positive emerging treatment trend was the development of targeted programs for special need groups.

PDs revealed a variety of strategies that have promoted necessary adaptations to economic and political influences within the structure of managed behavioral care. Strategies such as varying treatment length, modality, and subspecialty care reflected necessary adaptations to diverse market needs.

Managed care continues to have a tremendous impact on the delivery of SAT services. While MC has helped to contain costs, negative outcomes are decreased availability of appropriate care and overtaxing of units that have survived MC cut backs. However, special need programs have allowed SAT programs to specialize, expand, and even flourish in today's competitive SAT market. Interviews with PDs reinforced the need for maintaining quality and diversified SAT services in today's MC environment.  相似文献   
40.
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