全文获取类型
收费全文 | 2194篇 |
免费 | 175篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 107篇 |
妇产科学 | 45篇 |
基础医学 | 214篇 |
口腔科学 | 26篇 |
临床医学 | 221篇 |
内科学 | 497篇 |
皮肤病学 | 14篇 |
神经病学 | 212篇 |
特种医学 | 214篇 |
外科学 | 158篇 |
综合类 | 34篇 |
一般理论 | 117篇 |
预防医学 | 233篇 |
眼科学 | 52篇 |
药学 | 122篇 |
1篇 | |
肿瘤学 | 103篇 |
出版年
2023年 | 12篇 |
2022年 | 15篇 |
2021年 | 36篇 |
2020年 | 14篇 |
2019年 | 26篇 |
2018年 | 39篇 |
2017年 | 33篇 |
2016年 | 22篇 |
2015年 | 30篇 |
2014年 | 30篇 |
2013年 | 60篇 |
2012年 | 66篇 |
2011年 | 91篇 |
2010年 | 59篇 |
2009年 | 57篇 |
2008年 | 93篇 |
2007年 | 69篇 |
2006年 | 78篇 |
2005年 | 74篇 |
2004年 | 77篇 |
2003年 | 62篇 |
2002年 | 52篇 |
2001年 | 58篇 |
2000年 | 77篇 |
1999年 | 71篇 |
1998年 | 39篇 |
1997年 | 37篇 |
1996年 | 56篇 |
1995年 | 41篇 |
1994年 | 44篇 |
1993年 | 40篇 |
1992年 | 55篇 |
1991年 | 59篇 |
1990年 | 59篇 |
1989年 | 78篇 |
1988年 | 59篇 |
1987年 | 60篇 |
1986年 | 61篇 |
1985年 | 57篇 |
1984年 | 32篇 |
1983年 | 29篇 |
1982年 | 32篇 |
1981年 | 24篇 |
1980年 | 23篇 |
1979年 | 23篇 |
1977年 | 22篇 |
1976年 | 27篇 |
1975年 | 19篇 |
1967年 | 13篇 |
1966年 | 17篇 |
排序方式: 共有2379条查询结果,搜索用时 16 毫秒
161.
162.
The posterior superior alveolar (PSA) injection technique has varied over time with respect to the depth and angle of penetration, the location for deposition of anesthetic agent, and the number of injections necessary to assure adequate anesthesia to the maxillary molars. Of the standard intraoral injections, the PSA carries with it the second highest risk for anesthesia complications. With changes in armamentarium and technique, the complication rates have declined and more often are associated with anatomical considerations with respect to neurovascular compromise and/or anesthetic solution. In this study, the PSA injection technique and complication histories were investigated. Seventeen variations to the technique are reported along with 12 injection complications. A historic injection complication classification system is presented along with a management strategy based upon a review of reported provider experiences and treatment suggestions. 相似文献
163.
164.
165.
Callahan CM 《Medical care》2001,39(8):772-784
BACKGROUND: Two million older Americans suffer from depression annually. Depression causes more functional impairment than many other common medical conditions and older adults have the highest rate of suicide in the United States. Although many of these patients fail to seek or fail to receive care for depression, the majority will be seen in primary care for the treatment of other conditions. OBJECTIVE: To review the health services research on quality improvement for late life depression. METHODS: Qualitative literature review. RESULTS: During the past 30 years, multiple educational and quality improvement interventions have been designed and tested to improve the recognition and treatment of depression in primary care settings. The findings from this large body of health services research suggest that: (1) the outcome of major depression in the usual care of primary care is typically poor; this is particularly true of late life depression; (2) informational support provided to primary care physicians is necessary but insufficient to improve the outcomes of late life depression in primary care; achieving guideline-level therapy requires the substantial participation of an informed and motivated patient working in concert with a health care team and health care system designed to care for chronic conditions; (3) up to 30% of older primary care patients will fail to respond to excellent guideline-level therapy provided in primary care; and (4) the latest quality improvement efforts focus not only on the clinical skills of primary care physicians, but also on patient's self-care and on innovative strategies to improve the system of care. CONCLUSIONS: Late life depression is often a chronic disease and outcomes research demonstrates that quality improvement efforts that focus resources on improving systems of care and the active participation of patients offer the best evidence of improved patient outcomes. 相似文献
166.
Daley M Argeriou M McCarty D Callahan JJ Shepard DS Williams CN 《Journal of psychoactive drugs》2001,33(1):57-66
During the 1990s, substance abuse treatment programs were developed for pregnant women to help improve infant birth outcomes, reduce maternal drug dependency and promote positive lifestyle changes. This study compared the relative impact of five treatment modalities--residential, outpatient, residential/outpatient, methadone and detoxification-only--on infant birth weight and perinatal health care expenditures for a sample of 445 Medicaid-eligible pregnant women who received treatment in Massachusetts between 1992 and 1997. Costs and outcomes were measured using the Addiction Severity Index and data from birth certificates, substance abuse treatment records and Medicaid claims. Multiple regression was used to control for intake differences between the groups. Results showed a near linear relationship between birth weight and amount of treatment received. Women who received the most treatment (the residential/outpatient group) delivered infants who were 190 grams heavier than those who received the least treatment (the detoxification-only group) for an additional cost of $17,211. Outpatient programs were the most cost-effective option, increasing birth weight by 139 grams over detoxification-only for an investment of only $1,788 in additional health care and treatment costs. A second regression using five intermediate treatment outcomes--prenatal care, weight gain, relapse, tobacco use and infection--suggested that increases in birth weight were due primarily to improved nutrition and reduced drug use, behaviors which are perhaps more easily influenced in residential settings. 相似文献
167.
Margolis RL O'Hearn E Rosenblatt A Willour V Holmes SE Franz ML Callahan C Hwang HS Troncoso JC Ross CA 《Annals of neurology》2001,50(3):373-380
Huntington's disease (HD) is an autosomal dominant disorder characterized by abnormalities of movement, cognition, and emotion and selective atrophy of the striatum and cerebral cortex. While the etiology of HD is known to be a CAG trinucleotide repeat expansion, the pathways by which this mutation causes HD pathology remain unclear. We now report a large pedigree with an autosomal dominant disorder that is clinically similar to HD and that arises from a different CAG expansion mutation. The disorder is characterized by onset in the fourth decade, involuntary movements and abnormalities of voluntary movement, psychiatric symptoms, weight loss, dementia, and a relentless course with death about 20 years after disease onset. Brain magnetic resonance imaging scans and an autopsy revealed marked striatal atrophy and moderate cortical atrophy, with striatal neurodegeneration in a dorsal to ventral gradient and occasional intranuclear inclusions. All tested affected individuals, and no tested unaffecteds, have a CAG trinucleotide repeat expansion of 50 to 60 triplets, as determined by the repeat expansion detection assay. Tests for the HD expansion, for all other known CAG expansion mutations, and for linkage to chromosomes 20p and 4p were negative, indicating that this mutation is novel. Cloning the causative CAG expansion mutation for this new disease, which we have termed Huntington's disease-like 2, may yield valuable insight into the pathogenesis of HD and related disorders. 相似文献
168.
To further evaluate the serotonin (5-HT) neurotoxic potential of substituted amphetamines, we used tritiated proline to examine anterograde transport along ascending axonal projections originating in the rostral raphe nuclei of animals treated 3 weeks previously with (+/-)fenfluramine (FEN, 10 mg/kg, every 2 h x 4 injections; i.p.) or (+/-)3,4-methylenedioxymethamphetamine (MDMA, 20 mg/kg, twice daily for 4 days; s.c.). The documented 5-HT neurotoxin, 5,7-dihydroxytryptamine (5,7-DHT, 75 microg; ICV; 30 min after pretreatment with pargyline, 50 mg/kg; i.p., and desipramine 25 mg/kg; i.p.), served as a positive control. Along with anterograde axonal transport, we measured two 5-HT axonal markers, 5-HT and 5-hydroxyindoleacetic acid (5-HIAA). Prior treatment with FEN or MDMA led to marked reductions in anterograde transport of labeled material to various forebrain regions known to receive 5-HT innervation. These reductions were associated with lasting decrements in 5-HT axonal markers. In general, decreases in axonal transport were less pronounced than those in 5-HT and 5-HIAA. However, identical changes were observed after 5,7-DHT. These results further indicate that FEN and MDMA, like 5,7-DHT, are 5-HT neurotoxins. 相似文献
169.
The Notch receptor protein and its signaling pathway have been well conserved throughout evolution and appear to be pivotal components in cell fate decisions during development. Recent studies suggest that, depending on the cellular and developmental context, Notch signaling may also affect cell proliferation and programmed cell death. Mammals have four related Notch genes. One of these, designated Notch-4, was found to be a common integration site for the mouse mammary tumor virus in mouse mammary tumors. One consequence of this type of viral integration event is the ectopic expression of the intracellular domain of Notch-4 that corresponds to a gain-of-function mutation. Expression of activated Notch-4 in mammary epithelium has profound effects on mammary gland development and tumorigenesis. In this review, we briefly summarize the structure and function of the Notch receptor, as well as the components that comprise and modify the signaling pathway. Finally we discuss the potential role of Notch in mammary gland development and tumorigenesis. 相似文献
170.
OBJECTIVE: To explore concurrent and predictive validity of the Stanford-Binet: Fourth Edition (SB-IV) by comparing scores on the SB-IV with scores from the Battelle Developmental Inventory (BDI) and later achievement scores in preschoolers at risk due to very low birthweight, and/or intraventricular hemorrhage (IVH) and other medical complications. METHODS: At ages 3,4, and 5, 92 preschoolers were tested with the SB-IV and BDI as part of an 8-year early intervention follow-up. RESULTS: The SB-IV and BDI concurrent correlations at ages 3, 4, and 5 were statistically significant (r = .73-.78, p < .0001), as were predictive correlations (r = .58-.85, p < .0001). However, the BDI and SB-IV failed to place the children in the same categories for intervention services. With the BDI as the comparison measure, SB-IV failed to detect 87% of the children who were "delayed" (by BDI) at age 3 and 50% of the "delayed" children at age 5. CONCLUSIONS: Caution is recommended when using the SB-IV to assess high risk for early intervention eligibility. 相似文献