全文获取类型
收费全文 | 50072篇 |
免费 | 3511篇 |
国内免费 | 1675篇 |
专业分类
耳鼻咽喉 | 107篇 |
儿科学 | 615篇 |
妇产科学 | 350篇 |
基础医学 | 5436篇 |
口腔科学 | 724篇 |
临床医学 | 3021篇 |
内科学 | 4770篇 |
皮肤病学 | 240篇 |
神经病学 | 3891篇 |
特种医学 | 1394篇 |
外国民族医学 | 2篇 |
外科学 | 1577篇 |
综合类 | 4665篇 |
现状与发展 | 2篇 |
一般理论 | 1篇 |
预防医学 | 4333篇 |
眼科学 | 154篇 |
药学 | 16657篇 |
12篇 | |
中国医学 | 5845篇 |
肿瘤学 | 1462篇 |
出版年
2024年 | 139篇 |
2023年 | 636篇 |
2022年 | 1220篇 |
2021年 | 1527篇 |
2020年 | 1421篇 |
2019年 | 1360篇 |
2018年 | 1368篇 |
2017年 | 1547篇 |
2016年 | 1480篇 |
2015年 | 1461篇 |
2014年 | 2734篇 |
2013年 | 3895篇 |
2012年 | 2707篇 |
2011年 | 3204篇 |
2010年 | 2298篇 |
2009年 | 2409篇 |
2008年 | 2473篇 |
2007年 | 2487篇 |
2006年 | 2087篇 |
2005年 | 1850篇 |
2004年 | 1531篇 |
2003年 | 1376篇 |
2002年 | 1184篇 |
2001年 | 1078篇 |
2000年 | 826篇 |
1999年 | 820篇 |
1998年 | 786篇 |
1997年 | 684篇 |
1996年 | 689篇 |
1995年 | 636篇 |
1994年 | 532篇 |
1993年 | 506篇 |
1992年 | 516篇 |
1991年 | 452篇 |
1990年 | 425篇 |
1989年 | 467篇 |
1988年 | 400篇 |
1987年 | 366篇 |
1986年 | 357篇 |
1985年 | 472篇 |
1984年 | 427篇 |
1983年 | 291篇 |
1982年 | 373篇 |
1981年 | 292篇 |
1980年 | 299篇 |
1979年 | 217篇 |
1978年 | 229篇 |
1977年 | 166篇 |
1976年 | 201篇 |
1975年 | 85篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
目的探讨多层螺旋CT(MSCT)肺密度测定对结缔组织病(CTD)肺间质病变(ILL)早期诊断的临床意义。方法对222例CTD患者及50名正常对照者,应用MSCT附带的Pulmo自动评估软件进行上、中、下肺区的密度测定,并同时进行肺高分辨扫描(}-IR(_1、),分析二者的变化与CTD伴ILL的关系。结果222例cm患者中197例平均肺密度有不同程度的增高,25例平均肺密度正常。157例HRCT有不同程度的肺间质病变,65例HRCT正常。50名正常对照者HRCT均正常,8名平均肺密度有不同程度的增高,42名平均肺密度正常。结论采用MSCT与HRCT对CTD伴ILL的检测结果差异有统计学意义,P=0.000(双侧),因此MSCT平均肺密度测定对早期诊断CTD伴ILL比HRCT更敏感,更有临床意义。 相似文献
72.
本文介绍了42例室性心动过速的临床资料和特点,讨论了早期后除极与室性心动过速的关系,并探讨各型室速的治疗。 相似文献
73.
An ecologically based examination of barriers to physical activity in students from grade seven through first-year university 总被引:1,自引:0,他引:1
Nancy C. Gyurcsik Ph.D. Kevin S. Spink Ph.D. Steven R. Bray Ph.D. Karen Chad Ph.D. Matt Kwan B.Sc. 《The Journal of adolescent health》2006,38(6):704-711
PurposeThe first purpose was to identify barriers to physical activity that students in grade seven through first-year university experienced. A second purpose was to classify barriers using an ecological framework and to examine the pattern of barrier categories (i.e., intrapersonal, interpersonal, institutional, community, public policy, and physical environmental) and specific barrier types as grade increased. The use of an ecological model addressed limitations in prior research revolving around the identification of salient barriers in a manner that makes the design of effective interventions difficult.MethodsParticipants in grades 7–8 (n = 35), 9–10 (n = 67), 11–12 (n = 80), and the freshmen year of university (n = 109) listed barriers to physical activity on an open-ended measure.ResultsFindings revealed a trend for the average number of barriers reported per student to increase as grade in school increased. First-year university students reported significantly more barriers than all other grade groupings. The frequency of barriers reported within the ecological categories was dependent on the specific grade groupings. Further, within each ecological category, distinct barriers were reported across the different grade groupings.ConclusionsFindings highlight the utility of using an ecological model to categorize barriers, rather than simply classifying barriers as internal or external to an individual, as done in prior research. Understanding the pattern of ecologically based barrier categories and specific types of barriers will help to inform the content of future research and interventions designed to alleviate salient barriers to physical activity. 相似文献
74.
Intervention studies aimed at promoting increased physical activity have been trialled in many different settings including primary care, worksites and the community. Churches are also potential settings for physical activity promotion. However, little is known about the effectiveness of this setting for promoting physical activity, particularly in Australia. The purpose of this study was to evaluate the effectiveness of a mind, body and spiritually based health promotion program in increasing physical activity and promoting mental and spiritual health. Nineteen women completed the 8-week intervention, and 30 women in a non-health related 8-week program at the same church comprised a comparison group. Pre- and post-program surveys assessed outcome measures. Between-group differences over time were examined using one-way MANOVA's. Physical activity was higher in the intervention group than the comparison group. In contrast to the comparison group, both mental health (depression symptoms) and spiritual health improved significantly more among intervention participants. The data highlight the potential for a church-based setting and holistic approach to health promotion as a successful means of increasing physical activity and promoting mental and spiritual health among Australian women. 相似文献
75.
Abdulbari BENER Omer F. EL‐RUFAIE Saadat KAMRAN Ana B. GEORGIEVSKI Abdulaziz FAROOQ Martin RYSAVY 《International journal of rheumatic diseases》2006,9(3):257-263
Objective: The aim of this study was to determine the prevalence of low back pain (LBP) in a primary care setting population and examine its association with the symptoms of depression and somatization. Methods: This is a cross‐sectional study, utilising a survey carried out in primary health care clinics (PHCs) in Al‐Ain, United Arab Emirates (UAE). A multistage stratified sampling design was used and a representative sample of 1304 UAE nationals aged 18–65 years who attended PHC clinics for any reason were included and 1103 (84.5%) subjects agreed to participate and responded to the questionnaire during a period from June 2001 to January 2002. A specially designed questionnaire with three parts was used for the data collection: socio‐demographic information of the studied subjects, modified version of the Roland‐Morris scale for evaluating back‐related functional disability and SCL‐90 R for depression and somatization subscales was used to assess depressive and somatic symptoms. Results: Of the total number of subjects surveyed (1103), 586 (53.1%) were men and 517 (46.9%) women. The mean age was 34.9 ± 13.4 years for men and 33.5 ± 11.8 years for women. The prevalence of LBP in the studied subjects was 64.7% (95% CI, 60.7–68.5] with 46.7% among men and 53.3% among women. There were a significant differences between the subjects with LBP and without LBP with respect to gender (P < 0.001), body mass index (BMI) (P < 0.001), occupational status (P < 0.001) and living environment (P = 0.016). Functional disability was higher in patients with LBP. Young patients in aged 15–34 years, patients with preparatory/secondary educational level and students showed higher depressive symptoms. A similar pattern was found in patients with somatic symptoms. Factor analysis revealed a strong association between depression and somatization in LBP patients. Conclusions: Functional disability was higher in with LBP. Furthermore, symptoms of depression and somatization are prevalent among LBP patients. 相似文献
76.
Aoyama Takao Yamamoto Koujirou Kotaki Hajime Sawada Yasufumi Iga Tatsuji 《Pharmaceutical research》1997,14(11):1601-1606
Purpose. The locomotive activity changes after intravenous (i.v.) administration of methylphenidate (MPD) in rats were pharmacodynamically analyzed.
Methods. MPD concentration in plasma, MPD concentration and dopamine (DA) level in striatal dialysate collected by microdialysis method, and the locomotor activity after i.v. administration of MPD (2, 5 and 10 mg/kg doses) were used for the analysis.
Results. The transport of MPD from plasma to the interstitial fluid in the brain could be expressed by the linear two-compartment model. The clockwise hysteresis between the MPD concentration and the DA level in the dialysate could be explained by the pharmacodynamic model considering Michaelis-Menten type reuptake process of the extracellular DA into the terminal of the dopaminergic nerve and its competitive inhibition by the extracellular MPD. The inhibition constant (Ki) of MPD for DA reuptake was estimated to be 41.3 ± 73.8 nM (mean ± SE), which was closely consistent with the in vitro value after correction with dialysis recovery. The relationship between DA level in dialysate and locomotor activity was expressed by the Emax model considering two contrary effects, hyperkinesia and stereotypy. The bi-phasic locomotor activity-time profiles after high dose of MPD could be represented by this model.
Conclusions. The developed model made it possible to explain the tolerance in DA increase and the complicated locomotive change induced by MPD, and may be useful for other DA reuptake inhibitors, such as amphetamine and methamphetamine. 相似文献
77.
蛋黄磷脂中磷脂酰乙醇胺的薄层扫描测定 总被引:2,自引:1,他引:1
将超临界CO2萃取法得到的蛋黄粉中的磷脂经薄层色谱分离,采用双波长薄层扫描仪对其磷脂酰乙醇胺进行测定。平均回收率为97.67%,RSD为2.31%。 相似文献
78.
Summary Two cases of meningiomas, which are considered to have been caused by the preceding irradiation, are reported. In both cases, the cytokinetic study of the tumour using bromodeoxyuridine (BrdU) was performed. The percent of the tumour cells in the S phase of the cell cycle was less than 1% in both cases. The low labelling indices might suggest a relatively slow growing potential of these tumours, though the radiation-induced meningiomas were reported as being rapidly growing and malignant. 相似文献
79.
In the present study, chlorogenic acid (CGA) isolated from Anthocephalus cadamba was screened for hepatoprotective activity by in vitro and in vivo assay methods using carbon tetrachloride (CCl4) as a model of liver injury. Intraperitoneal administration of CGA to mice at a dose of 100 mg/kg body weight for 8 days caused significant reversal in lipid peroxidation, enzymatic leakage, cytochrome P450 (Cyt P450) inactivation and produced enhancement of cellular antioxidant defence in CCl4-intoxicated mice, revealing that the antioxidative action of CGA is responsible for its liver protective activity. CGA exhibited a better therapeutic protective action than silymarin (SM), in CCl4-administered mice. 相似文献
80.
R. Alan Aitken Michael C. Bibby John A. Double Andrea L. Laws Robert B. Ritchie David W. J. Wilson 《Archiv der Pharmazie》1997,330(7):215-224
A range of 18 derivatives of flavone-8-acetic acid (FAA) with substituents on the 2-phenyl group have been prepared and their anti-tumour activity evaluated in vitro against a panel of human and murine tumour cell lines and in vivo against MAC 15A. There was no clear-cut relationship between in vitro and in vivo activity but the activity in each situation was found to be very sensitive to the precise substitution pattern with closely related isomers giving widely different activities. Some of the compounds, notably 10b,cj , and r , were active in vivo and these require further studies in order to evaluate their potential for development. 相似文献