全文获取类型
收费全文 | 18832篇 |
免费 | 1197篇 |
国内免费 | 83篇 |
专业分类
耳鼻咽喉 | 173篇 |
儿科学 | 496篇 |
妇产科学 | 387篇 |
基础医学 | 2148篇 |
口腔科学 | 327篇 |
临床医学 | 1559篇 |
内科学 | 3969篇 |
皮肤病学 | 228篇 |
神经病学 | 1039篇 |
特种医学 | 530篇 |
外科学 | 3323篇 |
综合类 | 647篇 |
一般理论 | 17篇 |
预防医学 | 1457篇 |
眼科学 | 514篇 |
药学 | 1868篇 |
中国医学 | 222篇 |
肿瘤学 | 1208篇 |
出版年
2023年 | 173篇 |
2022年 | 528篇 |
2021年 | 673篇 |
2020年 | 430篇 |
2019年 | 542篇 |
2018年 | 655篇 |
2017年 | 457篇 |
2016年 | 366篇 |
2015年 | 505篇 |
2014年 | 706篇 |
2013年 | 893篇 |
2012年 | 1308篇 |
2011年 | 1289篇 |
2010年 | 744篇 |
2009年 | 576篇 |
2008年 | 1006篇 |
2007年 | 1000篇 |
2006年 | 917篇 |
2005年 | 848篇 |
2004年 | 781篇 |
2003年 | 699篇 |
2002年 | 588篇 |
2001年 | 543篇 |
2000年 | 488篇 |
1999年 | 391篇 |
1998年 | 143篇 |
1997年 | 114篇 |
1996年 | 107篇 |
1995年 | 118篇 |
1994年 | 60篇 |
1993年 | 75篇 |
1992年 | 203篇 |
1991年 | 187篇 |
1990年 | 163篇 |
1989年 | 171篇 |
1988年 | 135篇 |
1987年 | 154篇 |
1986年 | 123篇 |
1985年 | 135篇 |
1984年 | 110篇 |
1983年 | 86篇 |
1982年 | 59篇 |
1981年 | 60篇 |
1979年 | 97篇 |
1978年 | 64篇 |
1977年 | 66篇 |
1975年 | 61篇 |
1974年 | 51篇 |
1973年 | 54篇 |
1972年 | 50篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
This study estimated the recurrent cost implications of adopting Integrated Management of Childhood Illness (IMCI) at the first-level healthcare facilities in Bangladesh. Data on illnesses of children who sought care either from community health workers (CHWs) or from paramedics over a four-month period were collected in a rural community. A total of 5,505 children sought care. About 75% of symptoms mentioned by mothers were directly related to illnesses that are targeted in the IMCI. Cough and fever represented 64% of all reported complaints. Referral of patients to higher facilities varied from 3% for the paramedics to 77% for the CHWs. Had the IMCI module been followed, proportion of children needing referral should have been around 8%. Significant differences were observed between IMCI-recommended drug treatment and current practice followed by the paramedics. Adoption of IMCI should save about US$ 7 million on drugs alone for the whole country. Proper implementation of IMCI will require employment of additional health workers that will cost about US$ 2.7 million. If the current level of healthcare use is assumed, introduction of IMCI in Bangladesh will save over US$ 4 million. 相似文献
992.
Khan MA 《Journal of health, population, and nutrition》2002,20(2):130-137
To assess the knowledge on acquired immunodeficiency syndrome (AIDS) among female adolescents in Bangladesh, this study used data extracted from the Bangladesh Demographic and Health Survey (BDHS) 1996-1997. Of 1,446 ever-married women included in the study, most were currently married (96%), Muslims (92%) and from rural areas (91%). Only one in six adolescents had ever heard of AIDS. Of them, 57% reported AIDS as a fatal disease almost always, while only 22% believed that AIDS could be avoided. Multivariate analysis revealed that knowledge on AIDS was strongly and positively associated with education of female adolescents and their husbands and varied significantly across different parts of the country. Knowledge on AIDS was higher among relatively older and urban residents who had access to television or radio and whose husbands were using condom. Strong efforts are needed to improve awareness and to clarify misconceptions about AIDS. Improved access to education, mass-media, and promotion of condom use could prevent AIDS among female adolescents in Bangladesh. 相似文献
993.
Determination of aristolochic acid I and II in North American species of Asarum and Aristolochia 总被引:1,自引:0,他引:1
Wild ginger, Asarum canadense, which has folk uses as a medicinal and food plant, has been reported to contain aristolochic acid I. Rhizomes of North American species of Aristolochiaceae were surveyed for the presence of aristolochic acids by HPLC. Aristolochic acid I (1) and aristolochic acid II (2) were present in Aristolochia species and Hexastylis; 1 alone was detected in multiple accessions of A. canadense and Asarum caudatum, though not in Asarum wagneri. Concentrations in A. canadense were highly variable, reaching as much as 0.037 percent of dry weight. 相似文献
994.
The steroidal saponin constituents obtained from Tribulus terrestris were tested for their antimicrobial and cytotoxic effects. The spirostanol-based steroidal saponins 1-3 exhibited remarkable activity against fungal organisms (Candida albicans and Cryptococcus neoformans) and cancer cell lines [human malignant melanoma (SK-MEL), human oral epidermoid carcinoma (KB), human breast ductal carcinoma (BT-549), and human ovary carcinoma (SK-OV-3)], while none of the compounds possessing the furostanol framework 4-7 showed activity. The most active spirostanol glycoside, compound 3 exhibited a broad range of anticancer activity against cell lines, SK-MEL, KB, BT-549 and SK-OV-3 at IC50s of 6.0, 7.0, 6.0 and 8.2 micrograms/ml, respectively, while compounds 1 and 2 showed selective cytotoxicity against SK-MEL at 6.7 and 9.1 micrograms/ml, respectively. The minimum inhibitory concentrations (MIC) in antifungal bioassay for compounds 1-3 varied from 1.5 to 6.2 micrograms/ml, which prompted to conclude certain structural features are required for these bioactivities. 相似文献
995.
2-Arylidene-4-(biphenyl-4-yl)but-3-en-4-olides also known as 3-arylidene-5-(biphenyl-4-yl)-2(3H)-furanones were prepared from 3-(4-phenyl-benzoyl) propionic acid and aromatic aldehydes. Some of the selected butenolides were reacted with ammonia and benzylamine to give corresponding pyrrolones and N-benzylpyrrolones respectively, which were characterized on the basis of 1H NMR and MS data and elemental analysis results. These compounds were tested for anti-inflammatory and anti-microbial actions. A few compounds were found to have promising anti-inflammatory activity while a fair in number of compounds showed a good anti-fungal activity and a promising antibacterial activity against S. aureus and E. coli. 相似文献
996.
Khan A Khan SR Shankles EB Polissar NL 《International clinical psychopharmacology》2002,17(6):281-285
Although early antidepressant clinical trials simply relied on a clinician's judgment as to whether a depressed patient clinically improved or not, the Hamilton Depression (HAM-D) rating scale has become the 'gold standard' to assess the efficacy of new antidepressants. The alternative Montgomery-Asberg Depression Rating Scale (MADRS) has not achieved general acceptance. However, its ease of use warrants evaluation as to whether it is comparable to HAM-D in its sensitivity in detecting antidepressant-placebo differences in antidepressant clinical trials. A retrospective chart review was performed on the records of 208 depressed adult patients that participated in eight randomized, placebo-controlled, double-blind antidepressant clinical trials at the Northwest Clinical Research Center between 1996 and 2000. We compared the effect sizes of the HAM-D, MADRS and Clinical Impressions Rating Scale (CGI-S for severity and CGI-I for improvement) for patients assigned to placebo or an established antidepressant. The effect size (measured as the mean change in rating with antidepressants minus the mean change for placebo divided by the pooled SD of change, adjusted for age, gender and initial scores) was 0.49 with MADRS, 0.53 with HAM-D, 0.55 with CGI-S and 0.59 with CGI-I. The four rating scales had similar effect sizes regardless of the type of antidepressant evaluated. These data suggest that MADRS is as sensitive an instrument as HAM-D for detecting antidepressant efficacy in clinical trials. Thus, MADRS may be a desirable tool in large-scale, pivotal antidepressant clinical trials. 相似文献
997.
Nazzal S Smalyukh II Lavrentovich OD Khan MA 《International journal of pharmaceutics》2002,235(1-2):247-265
The objectives of the present work were, first, to develop a self-nanoemulsified drug delivery system (SNEDDS) based on the eutectic properties of ubiquinone (CoQ10); and second, to study the progress of emulsion formation and drug release mechanisms by turbidimetry and droplet size analysis. Binary phase diagrams of CoQ10 with menthol and essential oils were constructed and used to develop the self-nanoemulsified formulation. Pseudo ternary phase diagram was constructed to identify the efficient self-emulsification region. Release mechanisms of the resultant formulas were quantified using turbidimetry in combination with dissolution studies. Turbidity time profiles revealed three distinctive regions: lag phase, plateau, and the pseudolinear phase. Lag phase was attributed to the liquid crystalline properties of the formula. Plateau turbidity was correlated with droplet size. Laser diffraction analysis revealed an average droplet diameter of 100 nm. Emulsification rate was obtained from the corrected slope of the pseudolinear phase of the profile. Stability of the formula was further evaluated using Fourier transform-infrared (FT-IR) attached to an attenuated total reflectance (ATR) accessory. The present study revealed a eutectic based semisolid self-emulsified delivery system that can overcome the drawbacks of the traditional emulsified systems such as low solubility and irreversible precipitation of the active drug in the vehicle with time. 相似文献
998.
Oral delivery of proteins: progress and prognostication 总被引:1,自引:0,他引:1
The delivery of proteins has gained momentum with the development of biotechnology sector that provided large-scale availability of therapeutic proteins. The availability is mostly due to the advances in recombinant DNA technology. The low oral bioavailability, however, continues to be a problem for several proteins because of their large molecular size, low permeation through biological membranes, and susceptibility to molecular changes in both biological and physical environments. The demand for effective delivery of proteins by the oral route has brought a tremendous thrust in recent years both in the scope and complexity of drug delivery technology. The important therapeutic proteins and peptides being explored for oral delivery include insulin, calcitonin, interferons, human growth hormone, glucagons, gonadotropin-releasing hormones, enkephalins, vaccines, enzymes, hormone analogs, and enzyme inhibitors. This article reviews the progress in oral delivery of these proteins, provides comments on the strategies to improve their oral bioavailability, and highlights their current market trends. 相似文献
999.
Feigley CE Bennett JS Lee E Khan J 《Applied occupational and environmental hygiene》2002,17(5):333-343
In specifying dilution ventilation flow rate, a safety factor, K, is often used to provide a margin of safety and to compensate for uncertainties and health impact severity. In current practice, the selection of K is very subjective. Here the component of K accounting for imperfect mixing, Km, was studied to develop more effective and efficient design procedures. Air flow and contaminant distribution in a 10 m x 3 m x 7 m room with a single contaminant source on a 1-m high table were simulated for steady, isothermal conditions using computational fluid dynamics. A series of 10 simulations explored factorial combinations of air exchange rates (1, 2,4, 8, 16 ACH) and inlet types (a high wall jet and a ceiling diffuser). Nine additional simulations explored exhaust opening location effects and 13 other simulations investigated source location effects. Km was calculated at each of 25,600 grid locations within the room by linear regression of emission rate/flow rate (G/Q) on concentration (C). The linear relationship between C and G/Q at each of the points was nearly perfect (R2 > 0.97). For the simulations with varying dilution flow rate, Km ranged from 0.19 to 2.86 for the wall jet and from 0.94 to 4.34 for the ceiling diffuser. Holding G/Q at 100 ppm and varying source and exhaust location produced room average concentrations from 55.7 to 173 ppm. Unlike orthodox design approaches, this work suggests that air monitoring data often can be used to calculate dilution flow rate requirements. Also, dilution flow rate requirements may be reduced by enhancing room mixing with fans or altering air inlet configuration. However, mixing should not be increased if the altered room air currents could transport contaminant to an occupant's breathing zone or interfere with other control methods that depend on segregation of incoming air and contaminant. 相似文献
1000.
BACKGROUND: Four principles are used to distribute payments via the Swedish social-insurance system in cases of temporary or permanent illness and death. This paper studies the redistributive effects on income of these four principles. METHODS: The analysis is based on aggregate social-insurance data from the 25 municipalities that comprise Stockholm County in Sweden. For nine different types of social-insurance payments based on the four principles, the degree of income redistribution is measured according to concentration indexes and differences between Gini coefficients with social-insurance payments excluded and included. RESULTS: The concentration indexes for payments from the nine social-insurance schemes in total is -0.0469. The Gini coefficient falls from 0.0437 excluding insurance payments (i.e. for income only from gainful work, IGW) to 0.0379 when including insurance payments with income from gainful work (IGW + TP). That is, the Gini coefficient is 15% lower when insurance payments are included. Decomposition by payment shows that the largest redistribution effect on income inequality is made by disability pension. CONCLUSION: Municipalities with low average income are favoured by the Swedish social-insurance system. Payment principles can be ranked according to their redistributive capacity: mix of compensating-lost-income and flat-rate, compensating-lost-income, means-testing, flat-rate, and need-based respectively. The nine social-insurance schemes contribute very differently to income redistribution. Disability pension and sickness allowance contribute most to income redistribution and reducing income inequality. 相似文献