全文获取类型
收费全文 | 193523篇 |
免费 | 2143篇 |
国内免费 | 97篇 |
专业分类
耳鼻咽喉 | 1261篇 |
儿科学 | 7131篇 |
妇产科学 | 3459篇 |
基础医学 | 19399篇 |
口腔科学 | 2313篇 |
临床医学 | 13843篇 |
内科学 | 34815篇 |
皮肤病学 | 1024篇 |
神经病学 | 18536篇 |
特种医学 | 9407篇 |
外科学 | 30662篇 |
综合类 | 2361篇 |
一般理论 | 5篇 |
预防医学 | 19092篇 |
眼科学 | 3011篇 |
药学 | 10962篇 |
中国医学 | 698篇 |
肿瘤学 | 17784篇 |
出版年
2023年 | 171篇 |
2022年 | 358篇 |
2021年 | 668篇 |
2020年 | 417篇 |
2019年 | 564篇 |
2018年 | 22469篇 |
2017年 | 17781篇 |
2016年 | 19991篇 |
2015年 | 1601篇 |
2014年 | 1612篇 |
2013年 | 1822篇 |
2012年 | 8549篇 |
2011年 | 22625篇 |
2010年 | 19595篇 |
2009年 | 12273篇 |
2008年 | 20689篇 |
2007年 | 22850篇 |
2006年 | 1692篇 |
2005年 | 3164篇 |
2004年 | 4273篇 |
2003年 | 5165篇 |
2002年 | 3192篇 |
2001年 | 445篇 |
2000年 | 570篇 |
1999年 | 305篇 |
1998年 | 326篇 |
1997年 | 319篇 |
1996年 | 166篇 |
1995年 | 174篇 |
1994年 | 147篇 |
1993年 | 94篇 |
1992年 | 90篇 |
1991年 | 142篇 |
1990年 | 180篇 |
1989年 | 132篇 |
1988年 | 100篇 |
1987年 | 98篇 |
1986年 | 59篇 |
1985年 | 70篇 |
1984年 | 51篇 |
1983年 | 57篇 |
1982年 | 45篇 |
1980年 | 54篇 |
1974年 | 31篇 |
1969年 | 25篇 |
1938年 | 60篇 |
1937年 | 25篇 |
1934年 | 30篇 |
1932年 | 56篇 |
1930年 | 46篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
991.
992.
Herman Nys Sander Welie Tina Garanis-Papadatos Dimitris Ploumpidis 《Health care analysis》2004,12(4):329-337
The discriminatory effects of categorizing psychiatric patients into competent and incompetent, have urged lawyers, philosophers and health care professionals to seek a functional approach to capacity assessment. Dutch and English law have produced some guidelines concerning this issue. So far, most legal systems under investigation have concentrated on alternatives for informed consent by the patient in case of mental incapacity, notably substitute decision-making, intervention of a judge and advance directives. It is hard to judge the way in which the law may further adapt to a more functional assessment of capacity, because the nature of law shows that legal reforms usually take place only when new methods have been accepted by the field. This is not yet the case today. 相似文献
993.
994.
995.
N Principi S Esposito R Gasparini P Marchisio P Crovari 《Archives of disease in childhood》2004,89(11):1002-1007
OBJECTIVE: A prospective, multicentre study was conducted to evaluate the burden of laboratory confirmed influenza in healthy children and their household contacts. METHODS: The patients were enrolled in four emergency departments (EDs) and by five primary care paediatricians (PCPs) in different Italian municipalities 2 days a week between November 1, 2001 and April 30, 2002. The study involved 3771 children less than 14 years of age with no chronic medical conditions who presented with a respiratory tract infection in EDs or PCP outpatient clinics during the study period. Nasopharyngeal swabs were collected for the isolation of influenza viruses and RNA detection. Information was also collected concerning respiratory illnesses and related morbidities among the study children and their household contacts. RESULTS: Influenza virus was demonstrated in 352 cases (9.3%). In comparison with the influenza negative children, those who were influenza positive had an older mean age, were more often attending day care centres or schools, more frequently experienced fever and croup, received more antipyretics, and had a longer duration of fever and school absence. Furthermore, their parents and siblings had more respiratory illnesses, received more antipyretics and antibiotics, needed more medical visits, missed more work or school days, and needed help at home to care for the ill children for a longer period of time. CONCLUSIONS: Influenza has a significant clinical and socioeconomic impact on healthy children and their families. Prevention strategies should also focus on healthy children regardless of their age because of their role in disease transmission. 相似文献
996.
Kramer HK Andria ML Kushner SA Esposito DH Hiller JM Simon EJ 《Brain research. Molecular brain research》2000,79(1-2):55-66
Opioid receptors are known for their ability to activate diverse second messenger systems. Previously, we showed that selective delta-opioid agonists were able to induce the rapid tyrosine phosphorylation of delta-opioid receptors (delta-ORs) through Src. Src-dependent tyrosine phosphorylation of delta-ORs appears to be important for activation of the mitogen-activated protein kinase cascade and for receptor sequestration into clathrin-coated endosomes, as the Src antagonist, PP1, inhibited both. In an attempt to clarify the role of tyrosine phosphorylation in delta-OR signalling and regulation, we constructed a mutant receptor in which the tyrosine located in the conserved NPXXY motif of the C-terminus was replaced by a phenylalanine (Y318F-delta-OR). Mutation of Y318 resulted in a receptor that was comparable to the wild type in its expression level in HEK-293 cells and in its affinity for opioid ligands. Both receptors showed effective coupling to G proteins and were capable of inhibiting forskolin-stimulated cAMP accumulation with similar potencies. However, the mutant receptor was able to stimulate (35)S-GTPgammaS binding with a lower EC(50) than the wild type receptor. The stimulation of tyrosine phosphorylation in delta-ORs by [D-Thr(2)]-Leu-enkephalin-Thr (DTLET) was significantly less in cells expressing the Y318F-delta-OR than in cells expressing the wild type. In addition, both rapid receptor internalization and down-regulation were markedly attenuated in the mutant. Finally, the mutant receptor was unable to induce a robust activation of the MAPK pathway, suggesting that tyrosine phosphorylation of the delta-OR protein is important for this signalling pathway. These findings implicate tyrosine phosphorylation of Y318 in receptor signalling and agonist-mediated regulation. 相似文献
997.
998.
P S F Barbosa A M C Martins A Havt Daniela O Toyama J S A M Evangelista D P P Ferreira P P Joazeiro Luis O S Beriam Marcos H Toyama M C Fonteles H S A Monteiro 《Toxicon》2005,46(4):376-386
Bothrops jararacussu myotoxin I (BthTx-I; Lys 49) and II (BthTX-II; Asp 49) were purified by ion-exchange chromatography and reverse phase HPLC. In this work we used the isolated perfused rat kidney method to evaluate the renal effects of B. jararacussu myotoxins I (Lys49 PLA2) and II (Asp49 PLA2) and their possible blockage by indomethacin. BthTX-I (5 microg/ml) and BthTX-II (5 microg/ml) increased perfusion pressure (PP; ct120=110.28+/-3.70 mmHg; BthTX I=171.28+/-6.30*mmHg; BthTX II=175.50+/-7.20*mmHg), renal vascular resistance (RVR; ct120=5.49+/-0.54 mmHg/ml.g(-1)min(-1); BthTX I=8.62+/-0.37*mmHg/ml g(-1)min(-1); BthTX II=8.9+/-0.36*mmHg/ml g(-1)min(-1)), urinary flow (UF; ct(120)=0.14+/-0.01ml g(-1)min(-1); BthTX I=0.32+/-0.05*ml g(-1)min(-1); BthTX II=0.37+/-0.01*ml g(-1)min(-1)) and glomerular filtration rate (GFR; ct120=0.72+/-0.10 ml g(-1)min(-1); BthTX I=0.85+/-0.13*ml g(-1)min(-1); BthTX II=1.22+/-0.28*ml g(-1)min(-1)). In contrast decreased the percent of sodium tubular transport (%TNa(+); ct(120)=79,76+/-0.56; BthTX I=62.23+/-4.12*; BthTX II=70.96+/-2.93*) and percent of potassium tubular transport (%TK(+);ct120=66.80+/-3.69; BthTX I=55.76+/-5.57*; BthTX II=50.86+/-6.16*). Indomethacin antagonized the vascular, glomerular and tubular effects promoted by BthTX I and it's partially blocked the effects of BthTX II. In this work also evaluated the antibacterial effects of BthTx-I and BthTx-II against Xanthomonas axonopodis. pv. passiflorae (Gram-negative bacteria) and we observed that both PLA2 showed antibacterial activity. Also we observed that proteins Also we observed that proteins chemically modified with 4-bromophenacyl bromide (rho-BPB) decrease significantly the antibacterial effect of both PLA2. In conclusion, BthTx I and BthTX II caused renal alteration and presented activity antimicrobial. The indomethacin was able to antagonize totally the renal effects induced by BthTx I and partially the effects promoted by BthTx II, suggesting involvement of inflammatory mediators in the renal effects caused by myotoxins. In the other hand, other effects could be independently of the enzymatic activity of the BthTX II and the C-terminal domain could be involved in both effects promoted for PLA2. 相似文献
999.
Daniela G Beghini Maria Alice da Cruz-H?fling Priscila Randazzo-Moura Léa Rodrigues-Simioni José Camilo Novello Stephen Hyslop Sérgio Marangoni 《Toxicon》2005,46(6):604-611
We have previously demonstrated that rabbit antisera raised against crotoxin from Crotalus durissus cascavella venom (cdc-crotoxin) and its PLA2 (cdc-PLA2) neutralized the neurotoxicity of this venom and its crotoxin. In this study, we examined the ability of these antisera to neutralize the neurotoxicity of Crotalus durissus terrificus and Bothrops jararacussu venoms and their major toxins, cdt-crotoxin and bothropstoxin-I (BthTX-I), respectively, in mouse isolated phrenic nerve-diaphragm preparations. Immunoblotting showed that antiserum to cdc-crotoxin recognized cdt-crotoxin and BthTX-I, while antiserum to cdc-PLA2 recognized cdt-PLA2 and BthTX-I. ELISA corroborated this cross-reactivity. Antiserum to cdc-crotoxin prevented the neuromuscular blockade caused by C. d. terrificus venom and its crotoxin at a venom/crotoxin:antiserum ratio of 1:3. Antiserum to cdc-PLA2 also neutralized the neuromuscular blockade caused by C. d. terrificus venom or its crotoxin at venom or toxin:antiserum ratios of 1:3 and 1:1, respectively. The neuromuscular blockade caused by B. jararacussu venom and BthTX-I was also neutralized by the antisera to cdc-crotoxin and cdc-PLA2 at a venom/toxin:antiserum ratio of 1:10 for both. Commercial equine antivenom raised against C. d. terrificus venom was effective in preventing the neuromuscular blockade typical of B. jararacussu venom (venom:antivenom ratio of 1:2), whereas for BthTX-I the ratio was 1:10. These results show that antiserum produced against PLA2, the major toxin in C. durissus cascavella venom, efficiently neutralized the neurotoxicity of C. d. terrificus and B. jararacussu venoms and their PLA2 toxins. 相似文献
1000.
Paul Gutwein Alexander Stoeck Svenja Riedle Daniela Gast Steffen Runz Thomas P Condon Alexander Marmé Minh-Chau Phong Otwin Linderkamp Alexander Skorokhod Peter Altevogt 《Clinical cancer research》2005,11(7):2492-2501
PURPOSE: The L1 adhesion molecule (CD171) is overexpressed in human ovarian and endometrial carcinomas and is associated with bad prognosis. Although expressed as a transmembrane molecule, L1 is released from carcinoma cells in a soluble form. Soluble L1 is present in serum and ascites of ovarian carcinoma patients. We investigated the mode of L1 cleavage and the function of soluble L1. EXPERIMENTAL DESIGN: We used ovarian carcinoma cell lines and ascites from ovarian carcinoma patients to analyze soluble L1 and L1 cleavage by Western blot analysis and ELISA. RESULTS: We find that in ovarian carcinoma cells the constitutive cleavage of L1 proceeds in secretory vesicles. We show that apoptotic stimuli like C2-ceramide, staurosporine, UV irradiation, and hypoxic conditions enhance L1-vesicle release resulting in elevated levels of soluble L1. Constitutive cleavage of L1 is mediated by a disintegrin and metalloproteinase 10, but under apoptotic conditions multiple metalloproteinases are involved. L1 cleavage occurs in two types of vesicles with distinct density features: constitutively released vesicles with similarity to exosomes and apoptotic vesicles. Both types of L1-containing vesicles are present in the ascites fluids of ovarian carcinoma patients. Soluble L1 from ascites is a potent inducer of cell migration and can trigger extracellular signal-regulated kinase phosphorylation. CONCLUSIONS: We suggest that tumor-derived vesicles may be an important source for soluble L1 that could regulate tumor cell function in an autocrine/paracrine fashion. 相似文献