全文获取类型
收费全文 | 9020篇 |
免费 | 640篇 |
国内免费 | 67篇 |
专业分类
耳鼻咽喉 | 62篇 |
儿科学 | 215篇 |
妇产科学 | 192篇 |
基础医学 | 1574篇 |
口腔科学 | 121篇 |
临床医学 | 892篇 |
内科学 | 2320篇 |
皮肤病学 | 125篇 |
神经病学 | 812篇 |
特种医学 | 177篇 |
外科学 | 709篇 |
综合类 | 41篇 |
一般理论 | 1篇 |
预防医学 | 792篇 |
眼科学 | 131篇 |
药学 | 771篇 |
中国医学 | 28篇 |
肿瘤学 | 764篇 |
出版年
2024年 | 11篇 |
2023年 | 117篇 |
2022年 | 263篇 |
2021年 | 402篇 |
2020年 | 208篇 |
2019年 | 278篇 |
2018年 | 327篇 |
2017年 | 237篇 |
2016年 | 227篇 |
2015年 | 319篇 |
2014年 | 359篇 |
2013年 | 507篇 |
2012年 | 719篇 |
2011年 | 725篇 |
2010年 | 395篇 |
2009年 | 369篇 |
2008年 | 616篇 |
2007年 | 659篇 |
2006年 | 584篇 |
2005年 | 534篇 |
2004年 | 438篇 |
2003年 | 437篇 |
2002年 | 392篇 |
2001年 | 25篇 |
2000年 | 38篇 |
1999年 | 52篇 |
1998年 | 72篇 |
1997年 | 54篇 |
1996年 | 35篇 |
1995年 | 23篇 |
1994年 | 12篇 |
1993年 | 16篇 |
1992年 | 10篇 |
1991年 | 11篇 |
1990年 | 7篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1987年 | 11篇 |
1986年 | 10篇 |
1985年 | 16篇 |
1984年 | 11篇 |
1982年 | 7篇 |
1981年 | 22篇 |
1980年 | 10篇 |
1978年 | 12篇 |
1977年 | 13篇 |
1976年 | 8篇 |
1975年 | 8篇 |
1974年 | 7篇 |
1966年 | 6篇 |
排序方式: 共有9727条查询结果,搜索用时 15 毫秒
11.
12.
Jones DL Weiss SM Chitalu N Villar O Kumar M Bwalya V Mumbi M 《American journal of infectious diseases》2007,3(4):169-176
An estimated 38.6 million persons globally are living with HIV, of whom over 1.1 million reside in Zambia. Of the 2 million cases in the US, 64% of new cases among women are among African Americans. Alcohol and drug use represents a significant risk factor for HIV transmission among both Zambians and African Americans. In addition, gender dynamics in both the US and Zambia promote transmission. This study examines two interventions targeting HIV risk behavior among HIV positive substance users, women in Miami, USA (the New Opportunities for Women (NOW) Project) and men in Lusaka, Zambia (the Partner Project). The study compares the efficacy of these two culturally tailored sexual behavior interventions provided in group and individual session formats. US and Zambian participants increased sexual barrier use and reduced substance-related sexual risk. Comparatively greater gains were made by higher risk Zambian males than US females in both group and individual conditions. Among lower risk participants, women in the group condition achieved and sustained the greatest comparative risk reductions. Results suggest that cost effective group HIV transmission risk reduction interventions for multiethnic individuals can be successfully implemented among both female and male drug and alcohol users in multinational settings. 相似文献
13.
Effect of olanzapine treatment on platelet glutamine synthetase-like protein and glutamate dehydrogenase immunoreactivity in schizophrenia. 总被引:1,自引:0,他引:1
Gulnur Sh Burbaeva Irina S Boksha Elena B Tereshkina Olga K Savushkina Marina S Turishcheva Lubov I Starodubtseva Oleg S Brusov Margarita A Morozova 《The world journal of biological psychiatry》2006,7(2):75-81
According to contemporary views, the glutamatergic system is implicated in the pathogenesis of schizophrenia, and atypical neuroleptics exert their effects (at least partially) through the glutamatergic system. Immunoreactive glutamate-metabolising enzymes, such as glutamine synthetase-like protein (GSLP) and two glutamate dehydrogenase isoenzymes (GDH), have been discovered in human platelets. The amount of GSLP in the platelets of 40 chronic patients with schizophrenia was found to be significantly higher than in 33 controls (consistent with our previous finding of increased amounts of GSLP in the prefrontal cortex of chronic schizophrenia patients). Moreover, survival analysis of the group of patients treated with olanzapine for 28 weeks showed that the larger amount of GSLP measured in platelets before treatment, the shorter the treatment time needed to achieve a positive clinical response (defined a priori as > or = 20% reduction in PANSS total score from the initial level before the treatment). Hence, GSLP level may serve as a predictor of the treatment duration to achieve a positive outcome with olanzapine. Both GSLP and GDH were found significantly changed in the course of treatment; hence, treatment with olanzapine influences the amounts of glutamate-metabolising enzymes in the platelets of chronic schizophrenia patients. 相似文献
14.
Peter Lavrenko Natalia Yevlampieva Olga Okatova Galina Kolbina Michael Olbrich 《Macromolecular chemistry and physics.》1997,198(11):3581-3598
Comb-like poly(methylsiloxane) macromolecules P4, P6, and P11, with side groups consisting of “phenyl benzoate” moieties and different alkyl spacers (from 4 to 11 C-atoms) between the backbone and the mesogenic side groups have been synthesized and investigated as well as low-molar-mass compounds M4, M6, and M11, as model molecules analogous to side chains of the macromolecule. The liquid-crystalline phase transition temperatures have been determined. Mobility of the mesogens and the macromolecule as a whole in dilute solution was studied in external fields (electric and mechanical shear field). In dilute solution under the influence of a sinusoidal electric field, the polymer behaviour is typical of flexible-chain polymer molecules where each mesogenic unit is oriented independently of the other ones. This is in contrast to the effect observed in a mechanical shear flow field. The Maxwell constant in positive for the solutions of compounds M4, M6, M11 and negative in polymers P4, P6, P11. This indicates the orientation of the macromolecule as a whole in the shear flow field, the mesogenic group main axis being oriented in the direction preferably normal to the macromolecular axis of primary polarizability. Temperature effects are also discussed. 相似文献
15.
Anna I. Suvorova Lyudmila Yu. Demchik Aza L. Peshekhonova Olga A. Sdobnikova 《Macromolecular chemistry and physics.》1993,194(5):1315-1321
The phase equilibrium of plasticized polymer systems on the basis of cellulose diacetate and ethylene glycol esters of dibasic aliphatic acids (from oxalic acid to 1,10-decanedicarboxylic acid) was studied and the solubility parameters and the thermodynamic interaction parameters of the components were calculated. It is shown that an increase in molecular weight of the plasticizers leads to a lower miscibility of the components, a fact which is reflected in a regular rise of the upper critical solution temperature (UCST), a tendency of the systems for gelation, a decrease of the solubility parameter of the plasticizer δ1, and a growth of the interaction parameters χH and χ12. The results are discussed in terms of the existing theories for polymer solutions. 相似文献
16.
17.
Sofya N Pchelina Andrei F Yakimovskii Olga N Ivanova Anton K Emelianov Andrei H Zakharchuk Alexander L Schwarzman 《Movement disorders》2006,21(12):2234-2236
Among mutations associated with autosomal dominant and sporadic Parkinson's disease (PD) the G2019S substitution in the leucine-rich repeat kinase 2 (LRRK2) gene is the most frequently identified. To estimate its frequency in Russia, we analyzed 208 patients with PD from the Northwestern region of Russia. Of these, 51 patients were probands from families with PD compatible with autosomal dominant inheritance. The control group represented 161 subjects without neurological disorders settled in the same region. The frequency of the G2019S mutation was greater in familial PD (2 [3.9%] of 51) than in sporadic PD (1 [0.6%] of 157). In addition, this mutation was found in the proband's father, who also had PD, in 1 PD family, and in 1 carrier without signs of PD at age 40 in another PD family. All carriers were heterozygous for the G2019S mutation and reported the Ashkenazi Jewish origin. The mutation was not found in the control group. 相似文献
18.
Tomáš Šimůnek Martin Štěrba Olga Popelová Michaela Adamcová Radomír Hrdina Vladimír Geršl 《Pharmacological reports : PR》2009,61(1):154-171
The risk of cardiotoxicity is the most serious drawback to the clinical usefulness of anthracycline antineoplastic antibiotics, which include doxorubicin (adriamycin), daunorubicin or epirubicin. Nevertheless, these compounds remain among the most widely used anticancer drugs. The molecular pathogenesis of anthracycline cardiotoxicity remains highly controversial, although the oxidative stress-based hypothesis involving intramyocardial production of reactive oxygen species (ROS) has gained the widest acceptance. Anthracyclines may promote the formation of ROS through redox cycling of their aglycones as well as their anthracycline-iron complexes. This proposed mechanism has become particularly popular in light of the high cardioprotective efficacy of dexrazoxane (ICRF-187). The mechanism of action of this drug has been attributed to its hydrolytic transformation into the iron-chelating metabolite ADR-925, which may act by displacing iron from anthracycline-iron complexes or by chelating free or loosely bound cellular iron, thus preventing site-specific iron-catalyzed ROS damage. However, during the last decade, calls for the critical reassessment of this “ROS and iron” hypothesis have emerged. Numerous antioxidants, although efficient in cellular or acute animal experiments, have failed to alleviate anthracycline cardiotoxicity in clinically relevant chronic animal models or clinical trials. In addition, studies with chelators that are stronger and more selective for iron than ADR-925 have also yielded negative or, at best, mixed outcomes. Hence, several lines of evidence suggest that mechanisms other than the traditionally emphasized “ROS and iron” hypothesis are involved in anthracycline-induced cardiotoxicity and that these alternative mechanisms may be better bases for designing approaches to achieve efficient and safe cardioprotection. 相似文献
19.
20.
JI Elizalde ; J Clemente ; JL Marin ; J Panes ; B Aragon ; A Mas ; JM Pique ; J Teres 《Transfusion》1997,37(6):573-576
BACKGROUND: Equilibration of hemoglobin concentration after transfusion has been estimated to take about 24 hours, but some studies have shown that earlier measurements reflect steady-state values in persons who have not bled recently. This study was aimed at assessing the changes over time in hemoglobin concentration after transfusion in acutely anemic patients because of recent bleeding. STUDY DESIGN AND METHODS: Thirty-two normovolemic patients recovering from an acute bleeding episode who were no longer thought to be bleeding and who received a 2- unit red cell transfusion were studied. At baseline and 15, 30, 60, and 120 minutes and 24 hours after transfusion, hemoglobin concentration and hematocrit values were measured. RESULTS: The administration of 2 units of packed red cells elicited a 24-hour increase of 22.4 +/− 6.8 g per L in hemoglobin concentration. Hemoglobin values were not different at any of the defined posttransfusion times. Hematocrit levels experienced similar changes over time. Agreement between 15-minute and 24-hour values was excellent, as only 6 percent of patients exhibited a clinically significant difference (> 6 g/L) between the hemoglobin measurements. CONCLUSION: Hemoglobin and hematocrit values rapidly equilibrate after transfusion in normovolemic patients who are recovering from an acute bleeding episode. This fact would allow a rapid assessment of the effects of transfusion and of the recurrence of bleeding in patients remaining at risk. 相似文献