全文获取类型
收费全文 | 13494篇 |
免费 | 905篇 |
国内免费 | 29篇 |
专业分类
耳鼻咽喉 | 121篇 |
儿科学 | 420篇 |
妇产科学 | 483篇 |
基础医学 | 1806篇 |
口腔科学 | 131篇 |
临床医学 | 2582篇 |
内科学 | 2312篇 |
皮肤病学 | 240篇 |
神经病学 | 1176篇 |
特种医学 | 253篇 |
外科学 | 1118篇 |
综合类 | 111篇 |
一般理论 | 17篇 |
预防医学 | 1737篇 |
眼科学 | 118篇 |
药学 | 833篇 |
中国医学 | 13篇 |
肿瘤学 | 957篇 |
出版年
2023年 | 50篇 |
2022年 | 89篇 |
2021年 | 209篇 |
2020年 | 134篇 |
2019年 | 253篇 |
2018年 | 296篇 |
2017年 | 183篇 |
2016年 | 241篇 |
2015年 | 266篇 |
2014年 | 396篇 |
2013年 | 659篇 |
2012年 | 973篇 |
2011年 | 1044篇 |
2010年 | 541篇 |
2009年 | 489篇 |
2008年 | 1017篇 |
2007年 | 1041篇 |
2006年 | 1030篇 |
2005年 | 993篇 |
2004年 | 933篇 |
2003年 | 871篇 |
2002年 | 894篇 |
2001年 | 93篇 |
2000年 | 60篇 |
1999年 | 123篇 |
1998年 | 204篇 |
1997年 | 131篇 |
1996年 | 123篇 |
1995年 | 103篇 |
1994年 | 95篇 |
1993年 | 90篇 |
1992年 | 60篇 |
1991年 | 51篇 |
1990年 | 59篇 |
1989年 | 46篇 |
1988年 | 47篇 |
1987年 | 44篇 |
1986年 | 37篇 |
1985年 | 34篇 |
1984年 | 41篇 |
1983年 | 47篇 |
1982年 | 60篇 |
1981年 | 51篇 |
1980年 | 49篇 |
1979年 | 20篇 |
1978年 | 29篇 |
1977年 | 20篇 |
1976年 | 20篇 |
1975年 | 16篇 |
1974年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
32.
Michael F Parry Brenda Grant Anthony Iton Patricia D Parry Diane Baranowsky 《Infection control and hospital epidemiology》2004,25(11):929-932
BACKGROUND: The need to improve influenza vaccination delivery in our community became painfully clear during the winter of 1997-1998 when high rates of respiratory illness led to congestion in the emergency department and a critical shortage of hospital beds. In response, the local hospital and the Department of Health launched a collaborative program to increase influenza vaccine coverage in the community. METHODS: The partnership was designed to increase the number of citizens receiving influenza vaccine and to moderate the severity of lower respiratory tract illness during the winter season. A variety of methods were used to increase public awareness, enhance vaccine delivery, and create a relatively seamless service for the community. RESULTS: During three seasons, influenza vaccination rates increased by a relative 150%. This represented immunization of 16% of the entire community and more than 75% of residents older than 65 years. Hospital employee vaccination rates also rose from 34% to 58%. When compared with other hospitals in the county, the campaign reduced the average number of annual visits to the emergency department for all respiratory diagnoses by 34% and exacerbations of chronic obstructive pulmonary disease by 46%. CONCLUSIONS: This influenza vaccination program illustrates the potential for synergy that exists between local departments of health and community hospitals in successfully increasing vaccine delivery to the community. Furthermore, it also suggests that such efforts can be successful in reducing use of the emergency department, resulting in a positive impact on the health of the community. 相似文献
33.
We have examined the actions of vasoactive intestinal peptide (VIP) and certain other known immune modulators on a nuclear pool(s) of protein kinase C (PKC) in isolated rat splenocyte nuclei. Rat splenocyte nuclei pure by enzymatic and electron microscope criteria demonstrated a time- and concentration-dependent activation of nuclear PKC (nPKC) by VIP. A biphasic pattern of three bell-shaped curves was observed with peak phosphorylation at 10−15, 10−9 and 10−6M VIP. The phosphorylation of endogenous nuclear substrates was characterized as a PKC-mediated event by use of three known PKC inhibitors, 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), sphingosine, and staurosporine, which produced similar phosphate incorporation measurements. Also, this activity was blocked with the addition of a monoclonal antibody to PKC. Inhibitors of the ability of VIP to activate nPKC included somatostatin, 8-bromo-cAMP, peripheral benzodiazepine receptor modulators, and the PKC inhibitors, sphingosine and staurosporine. These data have direct relevance to our knowledge of cell-mediated immunity. 相似文献
34.
The following article reports on the results of service needs assessments of a cohort of youths released from a state psychiatric facility as perceived by service providers and families/caregivers. Families as well as service providers consistently agreed on three service areas of high need—psychotherapy for the child, family therapy and parent skill training. However, families perceived a need for a number of other services that are not traditionally provided by the mental health system such as after school recreation activities and self-help and support groups for the child. The discrepancies between service providers and families' perceptions of assessed needs may lead to families dropping out of service due to the unresponsiveness of the services in meeting their perceived needs. Steps that service providers need to take to be more responsive to the needs of families are discussed.This study was funded by a grant from the Office of Program Evaluation and Research, Ohio Department of Mental Health. 相似文献
35.
36.
In vivo MRI of cancer cell fate at the single-cell level in a mouse model of breast cancer metastasis to the brain. 总被引:7,自引:0,他引:7
Chris Heyn John A Ronald Soha S Ramadan Jonatan A Snir Andrea M Barry Lisa T MacKenzie David J Mikulis Diane Palmieri Julie L Bronder Patricia S Steeg Toshiyuki Yoneda Ian C MacDonald Ann F Chambers Brian K Rutt Paula J Foster 《Magnetic resonance in medicine》2006,56(5):1001-1010
Metastasis (the spread of cancer from a primary tumor to secondary organs) is responsible for most cancer deaths. The ability to follow the fate of a population of tumor cells over time in an experimental animal would provide a powerful new way to monitor the metastatic process. Here we describe a magnetic resonance imaging (MRI) technique that permits the tracking of breast cancer cells in a mouse model of brain metastasis at the single-cell level. Cancer cells that were injected into the left ventricle of the mouse heart and then delivered to the brain were detectable on MR images. This allowed the visualization of the initial delivery and distribution of cells, as well as the growth of tumors from a subset of these cells within the whole intact brain volume. The ability to follow the metastatic process from the single-cell stage through metastatic growth, and to quantify and monitor the presence of solitary undivided cells will facilitate progress in understanding the mechanisms of brain metastasis and tumor dormancy, and the development of therapeutics to treat this disease. 相似文献
37.
38.
Diane Hart 《Plastic surgical nursing》2003,23(2):55-63, 72
Having nice breasts is important to many women and their self-images. For those women who have had congenital deformities, were not blessed naturally with the shape they wanted, have had experiences that have adversely affected breast tissue, or have had a mastectomy as a result of breast cancer, breast implants can provide a boost in self-confidence. This article provides an overview of breast implant issues and treatments, and reviews breast implant complications, their potential causes and treatments. 相似文献
39.
Objective: Microvascular pericytes may contract in two different ways: In the first, a circumferential or radial mechanical force applied at right angles to the long axis of the vessel may constrict the underlying vessel affecting blood flow and transmural pressure. Retraction and elongation of pericyte processes may also occur tangentially and at right angles to the vessel axis and alter microvessel permeability by changing the amount of ablumenal surface covered or the openness of interendothelial junctions. In this study, cultured pericytes were utilized as a model experimental system to determine if vasoactive stimulation changes their shape in a manner consistent with this hypothesis. Methods: Pericytes cultured from isolated rate capillaries were subjected to angiotensin II and histamine. Their response was monitored by measuring the area of nonyielding substrate covered by the pericytes and the manner in which their shape changed. Shape changes were quantified by calculating the surface area: perimeter perimeter ratios. Results: Histamine significantly reduced surface area covered and the surface area: perimeter ratio. The pericyte processes retracted, resulting in elongated, spindle-shaped cells. These effects were nullified by the H1 blocker diphenhydramine suggesting a receptor-specific response. Angiotensin II also elicited contraction and reduced surface area, but the cells contracted laterally and longitudinally. The surface area: perimeter ratios also decreased. Conclusions: These results indicate that pericytes are capable of two types of contractile responses in culture, depending on the specific vasoactive stimulus. 相似文献
40.
Ahsan Y Khan Joe Carrithers Sheldon H Preskorn Rex Lear Stephen R Wisniewski A John Rush Diane Stegman Colleen Kelley Karen Kreiner Andrew A Nierenberg Maurizio Fava 《Annals of clinical psychiatry》2006,18(2):91-98
BACKGROUND: The purpose of this paper is to use demographic and clinical data from a large diverse group of outpatients diagnosed with non-psychotic major depression to investigate the validity of the DSM-IV concept of melancholic depression. METHODS: Baseline clinical and demographic data were collected on 1500 outpatients (1456 of whom melancholia could be determined) with non-psychotic major depressive disorder (MDD) participating in the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study. Depressive symptom severity was assessed by clinical telephone interview using the 17-item Hamilton Rating Scale for Depression (HRS-D17) and the 30-item Inventory of Depressive Symptomatology (IDS-C30). The types and degrees of concurrent psychiatric symptoms were measured using a self report, the Psychiatric Diagnostic Screening Questionnaire (PDSQ), by recording the number of items relevant to each diagnostic category endorsed by study participants. RESULTS: Adjusting for severity of depression (as measured by the total HRS-D17 scores), no differences were found in the rate of melancholic depression by race, marital status, education, employment status, family history of depression, primary care versus specialty care, monthly income, and degree of psychiatric and medical co-morbidity. Melancholic depression was significantly more likely in men than women. Melancholic depression after adjustment for severity was associated with a slightly younger age at study entry, as well as with greater illness severity, and slightly shorter duration of current episode. Hispanic ethnicity was associated with lower melancholic depression rates at the .06 level of significance. CONCLUSIONS: Among outpatients with MDD, melancholic features were less likely in Hispanic patients, but more likely in slightly younger patients and in men. Melancholic features were also related to a slightly shorter current episode. These findings are consistent with the notion that external socio-demographic factors do not play an important role in the pathophysiology of melancholic depression. 相似文献