全文获取类型
收费全文 | 39196篇 |
免费 | 2689篇 |
国内免费 | 956篇 |
专业分类
耳鼻咽喉 | 102篇 |
儿科学 | 585篇 |
妇产科学 | 321篇 |
基础医学 | 5178篇 |
口腔科学 | 651篇 |
临床医学 | 2743篇 |
内科学 | 4421篇 |
皮肤病学 | 232篇 |
神经病学 | 3819篇 |
特种医学 | 1012篇 |
外国民族医学 | 2篇 |
外科学 | 1461篇 |
综合类 | 3074篇 |
现状与发展 | 2篇 |
预防医学 | 3832篇 |
眼科学 | 147篇 |
药学 | 10169篇 |
12篇 | |
中国医学 | 3638篇 |
肿瘤学 | 1440篇 |
出版年
2024年 | 83篇 |
2023年 | 541篇 |
2022年 | 850篇 |
2021年 | 1363篇 |
2020年 | 1224篇 |
2019年 | 1225篇 |
2018年 | 1196篇 |
2017年 | 1304篇 |
2016年 | 1226篇 |
2015年 | 1159篇 |
2014年 | 1986篇 |
2013年 | 3207篇 |
2012年 | 1760篇 |
2011年 | 2180篇 |
2010年 | 1455篇 |
2009年 | 1736篇 |
2008年 | 1721篇 |
2007年 | 1696篇 |
2006年 | 1432篇 |
2005年 | 1276篇 |
2004年 | 1117篇 |
2003年 | 1010篇 |
2002年 | 892篇 |
2001年 | 854篇 |
2000年 | 645篇 |
1999年 | 658篇 |
1998年 | 666篇 |
1997年 | 577篇 |
1996年 | 562篇 |
1995年 | 536篇 |
1994年 | 458篇 |
1993年 | 444篇 |
1992年 | 450篇 |
1991年 | 413篇 |
1990年 | 386篇 |
1989年 | 391篇 |
1988年 | 347篇 |
1987年 | 338篇 |
1986年 | 326篇 |
1985年 | 444篇 |
1984年 | 400篇 |
1983年 | 279篇 |
1982年 | 352篇 |
1981年 | 276篇 |
1980年 | 284篇 |
1979年 | 208篇 |
1978年 | 221篇 |
1977年 | 159篇 |
1976年 | 194篇 |
1975年 | 79篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
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
72.
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
73.
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
74.
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
75.
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
76.
Stanislw Ryng Zdzislw Machn Zbigniew Wieczorek Michal Zimecki Tadeusz Glowiak 《Archiv der Pharmazie》1997,330(11):319-326
A series of 5-aminomethinimino-3-methyl-4-isoxazolecarboxylic acid phenylamides 4 has been prepared by condensation of 5-amino-3-methyl-4-isoxazolecarboxylic acid phenylamides 1 with trichloroacetic aldehyde. Alcoholysis of trichloro derivatives 2 gave 5-alkoxymethine derivatives 3 which, on reaction with an appropriate amine, formed the corresponding compounds 4 . The compounds obtained were evaluated for their immunological activity. The properties of three compounds, described in this report, permitted inhibition of the immune response in all possible ways: diminishing both types of immune response ( 4d ), humoral immune response ( 4a ), or cellular immune response ( 4c ). Preparation 4d is comparable in its effectiveness to CsA, so it may be potentially used as an agent for prolongation of the function of transplanted organs. Two other compounds may potentially be used in cases where only one type the immune response is required for combating pathogen invasion. 相似文献
77.
Fiona C.L. Bull Ph.D. M.Sc. Elise C.C. Schipper M.A. Konrad Jamrozik M.B.B.S. D.Phil. FAFPHM Brian A. Blanksby Ph.D. M.Sc. Dip.Ed. 《Preventive medicine》1997,26(6):866-873
Background.Physical inactivity is recognized as an important public health issue. Yet little is known about doctors' knowledge, attitude, skills, and resources specifically relating to the promotion of physical activity. Our survey assessed the current practice, perceived desirable practice, confidence, and barriers related to the promotion of physical activity in family practice.Methods.A questionnaire was developed and distributed to all 1,228 family practitioners in Perth, Western Australia.Results.We received a 71% response (n= 789). Family practitioners are most likely to recommend walking to sedentary adults to improve fitness and they are aware of the major barriers to patients participating in physical activity. Doctors are less confident at providing specific advice on exercise and may require further skills, knowledge, and experience. Although they promote exercise to patients through verbal advice in the consultation, few use written materials or referral systems.Conclusions.There are significant differences between self-reports of current practice and perceived desirable practice in the promotion of physical activity by doctors. Future strategies need to address the self-efficacy of family physicians and involve resources of proven effectiveness. The potential of referral systems for supporting efforts to increase physical activity by Australians should be explored. 相似文献
78.
Nicoletta Desideri Isabella Sestili Maria Luisa Stein Stefano Manarini Giuseppe Dell'Elba Chiara Cerletti 《Archiv der Pharmazie》1997,330(4):100-106
6-[(4-Quinolinyl)oxy]hexanoic acids and the corresponding esters were designed and synthesized as inhibitors of the production of arachidonic acid metabolites. The inhibitory activities were assayed in vitro by evaluation of serum leukotriene B4 and thromboxane B2 production. While all 6-[(4-quinolinyl)oxy]hexanoic acids and their esters proved to be inactive, the N-alkyl-4-quinolones, obtained as by-products in their synthesis, were found to be a new class of leukotriene biosynthesis inhibitors. 相似文献
79.
羟基胆烷酸类衍生物的抗癌活性研究Ⅰ.3β,5α,6β-三羟基胆烷-24-酸及其衍生物的合成与体外抗癌活性 总被引:3,自引:0,他引:3
报道3β,5α,6β三羟基胆烷24酸及其衍生物的合成及对小鼠L1210白血病细胞的体外抗癌活性.实验表明3β,5α,6β三羟基胆烷24酸,3β,5α,6β三羟基胆烷24酸甲酯及3β,6β二乙酰氧基5α羟基胆烷24酸甲酯有较好的抗癌活性 相似文献
80.
采集23名产妇的脐带血和8名正常成人的外周血制备LAK细胞,随机分为4组,在培养第3,5,7,14天,分别利用MTT法和^125I-UdR释放法对4组LAK细胞的增殖力和杀伤活性进行了测定,同时用细胞毒方法测定培养7天的LAK细胞的免疫表型。结果发现,在不同培养时间,脐血来源的LAK细胞增殖力显著高于成人血LAK细胞(P〈0.05或P〈0.01),成人血清组,脐血血清组,红细胞组LAK细胞增殖力有 相似文献