全文获取类型
收费全文 | 13227篇 |
免费 | 761篇 |
国内免费 | 26篇 |
专业分类
耳鼻咽喉 | 99篇 |
儿科学 | 395篇 |
妇产科学 | 187篇 |
基础医学 | 1688篇 |
口腔科学 | 428篇 |
临床医学 | 1409篇 |
内科学 | 2626篇 |
皮肤病学 | 159篇 |
神经病学 | 1272篇 |
特种医学 | 359篇 |
外科学 | 2049篇 |
综合类 | 104篇 |
一般理论 | 10篇 |
预防医学 | 904篇 |
眼科学 | 306篇 |
药学 | 1045篇 |
中国医学 | 19篇 |
肿瘤学 | 955篇 |
出版年
2023年 | 104篇 |
2022年 | 134篇 |
2021年 | 238篇 |
2020年 | 220篇 |
2019年 | 316篇 |
2018年 | 300篇 |
2017年 | 282篇 |
2016年 | 313篇 |
2015年 | 308篇 |
2014年 | 434篇 |
2013年 | 678篇 |
2012年 | 889篇 |
2011年 | 894篇 |
2010年 | 479篇 |
2009年 | 478篇 |
2008年 | 815篇 |
2007年 | 860篇 |
2006年 | 801篇 |
2005年 | 729篇 |
2004年 | 716篇 |
2003年 | 677篇 |
2002年 | 615篇 |
2001年 | 145篇 |
2000年 | 116篇 |
1999年 | 154篇 |
1998年 | 175篇 |
1997年 | 164篇 |
1996年 | 124篇 |
1995年 | 111篇 |
1994年 | 117篇 |
1993年 | 89篇 |
1992年 | 94篇 |
1991年 | 105篇 |
1990年 | 97篇 |
1989年 | 95篇 |
1988年 | 80篇 |
1987年 | 87篇 |
1986年 | 83篇 |
1985年 | 105篇 |
1984年 | 79篇 |
1983年 | 70篇 |
1982年 | 97篇 |
1981年 | 53篇 |
1980年 | 51篇 |
1979年 | 56篇 |
1978年 | 40篇 |
1977年 | 34篇 |
1976年 | 36篇 |
1975年 | 28篇 |
1974年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Hovgaard Lars Brøndsted Helle Buur Anders Bundgaard Hans 《Pharmaceutical research》1995,12(3):387-392
A series of O-cyclopropane carboxylic acid ester prodrugs of various -blocking agents was synthesized. All prodrugs were hydrolyzed to give their parent compounds in aqueous phosphate buffer of pH 7.4 and in 80% human plasma. The half-lives in buffer solutions varied from 4 hours for the timolol prodrug to about 1 day for the prodrug of alprenolol. In human plasma the half-lives were shorter, ranging from 1 to 7 hours. The formation of the O-cyclopropane carboxylic acid ester derivatives significantly increased the lipophilicities of the -blockers as measured by the distribution coefficient between n-octanol and aqueous phosphate buffer of pH 7.4. To characterize the biomembrane permeability characteristics of the -blockers, transport properties across Caco-2 cell monolayers were investigated. An increase in lipophilicity resulted in a higher permeability of the prodrugs as compared to the parent compounds. Hence, acebutolol experienced an increment of a factor 17 on the apparent permeability coefficient, Papp, whereas Papp for the more lipophilic drug propranolol was increased by a factor of only 1.26. Some conversion of the prodrugs to their parent compounds was observed during the transport and appeared to be due to enzymatic intracellular metabolism.Deseaced. 相似文献
132.
Jan Petter Arnestad M.D. Anders Bengtsson M.D. Ph.D. Jan-Peter Bengtson M.D. Ph.D. Larsolof Hafstrom M.D. Ph.D. Heinz Redl Ph.D. Günther Schlag M.D. 《World journal of surgery》1995,19(6):861-866
Fourteen patients with liver tumor malignancy and sixteen patients with malignant melanoma localized to one limb were studied regarding leukocyte activation with the release of polymorphonuclear neutrophilic (PMN) elastase and of neopterin and formation of cytokines (TNF- and Il-6) during the surgical treatment. Patients undergoing liver resection (n=10), abdominal hysterectomy (n=10), or hip replacement surgery (n=10) served as control groups. Isolated hyperthermic liver perfusion was performed with cytostatic-containing perfusate (melphalan and cisplatinum). Patients with recurrent malignant melanoma confined to one limb underwent isolated hyperthermic limb perfusion with cytostatic-containing perfusate (melphalan). Blood samples for determination of PMN elastase, neopterin, TNF-, and IL-6 were drawn from the patients preoperatively, 1 minute before the start of the perfusion, 60 and 120 minutes after the start of the perfusion, and 24 hours postoperatively. Samples from the perfusate were drawn 60 minutes after the start of the perfusion. High concentrations of plasma PMN clastase were found both in patients undergoing liver and limb perfusion and in patients undergoing liver resection surgery. Elevated concentrations of Il-6 were found in the patients undergoing liver perfusion and in patients undergoing liver resection. In none of the patients were there increased concentrations of neopterin or TNF-. The perfusate contained high concentrations of PMN elastase, neopterin, and IL-6. This study also demonstrated that major surgery leads to elevated concentrations of PMN elastase and IL-6. An increase of PMN elastase and IL-6 was seen in response to perfusion and to surgical trauma.
Resumen Catorce pacientes con tumores malignos del hígado y 16 pacientes con melanoma maligno localizado en una extremidad fueron estudiados en relación con la activación de leucocitos con liberación de elastasa de PMN y de neopterina y la formación de citocinas (FNT- e IL-6) en el curso del tratamiento quirúrgico. Pacientes sometidos a resección del hígado (n=10), histerectomía abdominal (n=10) y reemplazo de cadera (n=10) sirvieron como grupos control. Se realizó perfusión hipertérmica aislada del hígado con perfusato citostácico (melfalán y cisplatino). Los pacientes con melanoma maligno recurrente confinado a una extremidad fueron sometidos a perfusión hipertérmica aislada de la extremidad con perfusato citostácico (melfalán). Se tomaron muestras de sangre para determinación preoperatoria de elastasa de PMN, neopterina, FNT- e IL-6, un minuto antes de comenzar la perfusión, 60 y 120 minutos después del comienzo de la perfusión y 24 horas después de la operación. Se tomaron muestras del perfusato a los 60 minutos luego del comienzo de la perfusión. Se encontraron altas concentraciones de elastasa de PMN tanto en los pacientes sometidos a perfusión hepática o de la extremidad, como en los pacientes sometidos a resección hepática. Se encontraron concentraciones elevadas de IL-6 en los pacientes sometidos a perfusión hepática y en los pacientes sometidos a resección del hígado. En ningún paciente se encontraron concentraciones aumentadas de neopterina o de FNT-. El perfusato contenía altas concentraciones de elastasa de PMN, neopterina e IL-6. Se encontró un aumento en la elastasa de PMN y en la IL-6 en respuesta a la perfusión y al trauma quirúrgico.
Résumé Quatorze patients ayant une tumeur maligne du foie et 16 patients ayant un mélanome malin localisé à une extrémité ont été étudiés en ce qui concerne l'activation des leucocytes associée à un relargage d'élastase PMN et de néoptérine ainsi que la formation de cytokinines (TNF- et IL-6) pendant le traitement chirurgical. Trente patients avant eu soit une résection hépatique (n=10), soit une hystérectomie abdominale (n=10) ou une prothèse de hanche (n=10) ont servi de témoins. On a perfusé le foie avec un perfusât de cytostatiques (mélphalane et cis-platine). Les patients ayant un mélanome malin d'une extrémité ont eu une perfusion isolée hyperthermique avec une perfusion de cytostatique (mélphanane). Des échantillons du sang ont été retirés pour déterminer les taux d'élastase PMN, de la néoptérine, du TNF-, et de l'IL-6 en préopératoire, une minute avant le début de la perfusion, 60 et 120 minutes après le début de la perfusion, et 24 heures postopératoirement. Des échantillons ont été retirés 60 minutes après le début de la perfusion. Des concentration élevées d'élastase PMN ont été retrouvées à la fois chez les patients ayant une perfusion hépatique et de l'extrémité et chez les patients ayant eu une résection du foie. Des concentration élevées en IL-6 ont été retrouvées chez le patient ayant une perfusion du foie et chez le patient ayant une résection hépatique. Les concentrations en néoptérine et en TNF- n'étaient pas élevées. Le liquide de perfusion contenait des concentrations élevées en élastase PMN, néoptérine et en IL-6. Cette étude démontre aussi que la chirurgie majeure est associée avec des concentrations élevées en PMN elastase et IL-6. Une augmentation en PMN-élastase et en IL-6 a été retrouvée en réponse à la perfusion et au traumatisme chirurgical.相似文献
133.
Kelly RH Danielsen BH Golding JM Anders TF Gilbert WM Zatzick DF 《Psychiatric services (Washington, D.C.)》1999,50(12):1584-1590
OBJECTIVE: Although poor prenatal care is detrimental to maternal and infant health, few studies have assessed the adequacy of prenatal care among women with psychiatric diagnoses. This investigation examined the association between chart-recorded psychiatric and substance use diagnoses at the time of delivery and adequacy of prenatal care among all women delivering babies in California hospitals during 1994 and 1995. METHODS: The authors undertook an archival analysis of data from the California Health Information for Policy Project (CHIPP), which consists of linked hospital discharge and birth certificate data for 1,094,178 deliveries in 1994 and 1995. The associations between International Classification of Diseases, 9th Revision, Clinical Modification psychiatric and substance abuse diagnoses and level of prenatal care were examined. Logistic regression analyses were conducted to assess the association between maternal diagnostic category and inadequate prenatal care while controlling for payment source, age, education, race, marital status, and parity (previous births). RESULTS: Women who received psychiatric and substance use diagnoses demonstrated significantly increased risk of inadequate prenatal care compared with women without those diagnoses. CONCLUSIONS: Psychiatric diagnoses were associated with an increased risk of inadequate prenatal care; the association between psychiatric and substance use diagnoses and poor prenatal care persisted even after the analysis controlled for known risk factors. Future investigations will need to elucidate the processes of prenatal care for women with psychiatric disorders so that preventive interventions can be developed. 相似文献
134.
A 38-year-old white female with primary hypertrophic pyloric stenosis is presented. The patient was admitted to our service with a history of upper digestive tract pain and postprandial vomiting since her 17th year of life. Diagnosis of benign pyloric stenosis was made preoperatively and the patient was successfully treated by Finney pyloroplasty. Primary hypertrophic pyloric stenosis in adults is a rare condition of unknown etiology. Only about 200 cases of primary hypertrophic pyloric stenosis in adults have been reported in the literature. 相似文献
135.
A novel suspension system was developed where monoglycerides were formulated together with fatty acids and subsequently admixed with antigens. In the present study, diphtheria toxoid was used as a model antigen primarily due to its weak immunological properties as well as to its importance as a future human vaccine for mucosal, particularly nasal immunization. The formulations were administered parenterally and/or nasally to mice whereafter the immune response was determined. In the present study, we have shown that mono-olein/oleic acid vesicles enhance the immunogenicity of admixed diphtheria toxoid in mice to the same level as Alum adsorbed (or Freund's complete adjuvant) when administered parenterally or nasally. It was also shown that the immunogenicity was linked to the length of the acyl chain of the lipids, where shorter acyl chains resulted in reduced titers. Furthermore, shorter acyl chains also gave rise to more pronounced toxic reactions at the injections sites, such as necrosis and alopeci, both of which were lacking when the optimal formulation consisting of mono-olein and oleic acid was used. Thus, this lipid matrix has in our view a great potential as an immunological adjuvant with an exceptionally simple and efficient preparation procedure without organic solvents and with low cost endogenous lipid based raw materials. 相似文献
136.
Human phase I vaccine trials of 3 recombinant asexual stage malaria antigens with Montanide ISA720 adjuvant 总被引:13,自引:0,他引:13
Allan Saul Gregor Lawrence Anne Smillie Christine M. Rzepczyk Carol Reed Darrin Taylor Karen Anderson Anthony Stowers Richard Kemp Anthony Allworth Robin F. Anders Graham V. Brown David Pye Peter Schoofs David O. Irving Shanny L. Dyer Graeme C. Woodrow William R. S. Briggs Rosemaria Reber Dieter Stürchler 《Vaccine》1999,17(23-24):3145-3159
Two phase I vaccine trials were conducted to test the immunogenicity and safety of a vaccine containing three recombinant malaria antigens from the asexual stage of Plasmodium falciparum. The three antigens are a fragment of MSP1 (190LCS.T3); MSP2 and a portion of RESA and were formulated in Montanide ISA720 adjuvant. These trials investigated the dose response of each antigen for eliciting both antibody and T-cell responses and the immunogenicity of a mixture of the antigens compared with the antigens injected separately. All three antigens elicited both antibody and T-cell responses. Strong T-cell responses were observed with 190LCS.T3 and RESA with stimulation indices exceeding 100 for peripheral blood leucocytes in some individuals. The antibody responses were generally weak. The human antibody responses observed with MSP2 in Montanide ISA720 were not significantly different from those obtained in an earlier trial which used MSP2 with alum as the adjuvant. No antigenic competition was observed: volunteers receiving a mixture of antigens had similar responses to those receiving the three antigens at separate sites. Tenderness and pain at the injection site were common over the first few days following immunization. In some volunteers, especially those receiving the highest doses tested, there was a delayed reaction at the injection site with pain and swelling occurring approximately 10 days after injection. 相似文献
137.
OBJECTIVE: To evaluate the efficacy and safety of intracameral lidocaine in cataract surgery compared to peribulbar anesthesia. DESIGN: A prospective, randomized, controlled study. PARTICIPANTS: A total of 200 consecutive cataract patients (200 eyes) participated. INTERVENTION: Eyes were randomly assigned to two groups: one group received 0.15 ml intracameral 1% unpreserved lidocaine combined with topical anesthesia (oxybuprocaine); the other group received 6 ml prilocaine peribulbar before phacoemulsification with sclerocorneal tunnel incision. MAIN OUTCOME MEASURES: Duration of surgery was measured; implicit time and amplitudes of the b-waves of the photopic electroretinogram (ERG) potentials (single-flash ERG and the 30-Hz flicker ERG) were recorded; frequencies of intraoperative problems, complications, intraoperative, and postoperative pain were evaluated. RESULTS: After lidocaine anesthesia combined with topical anesthesia, similar complications were found, longer operation time (P < 0.001), and significantly better visual acuity immediately after surgery (P < 0.001). The ERG amplitudes were not significantly reduced after 0.15-ml intracameral lidocaine half an hour after surgery (P > 0.05). CONCLUSION: Intracameral lidocaine 1% combined with topical anesthesia can be recommended as an alternative procedure to peribulbar anesthesia in cataract surgery with corneoscleral tunnel incision. 相似文献
138.
Accommodative facility training with a long term follow up in a sample of school aged children showing accommodative dysfunction 总被引:3,自引:0,他引:3
Sterner B Abrahamsson M Sjostrom A 《Documenta ophthalmologica. Advances in ophthalmology》1999,99(1):93-101
The primary aim of this project was to study the effect of flip lens-training on the accommodative function in a group of
children with accommodative dysfunction and subjective symptoms such as asthenopia, headache, blurred vision, and avoidance
of near activity. We also wanted to measure the accommodative facility among the children in comparison with a control group.
Another aim of the study was whether flip lens-training increased accommodative facility, and to find out if it also had a
positive effect on their asthenopia and related problems also in long term. Following the training period the accommodative
facility and accommodative function significantly increased and two years after finishing the training period no child had
regained any subjective symptoms and the objective findings were almost the same as at the end of facility training period.
These results suggest that accommodative facility training is an efficient method built on loss of symptoms among children
with accommodative infacility.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
139.
Norbert Anders Karl-Titus Hoffmann Norbert Hosten Tony Walkow Roland Felix Christian Hartmann 《Der Ophthalmologe : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft》1999,96(10):658-662
Dacryocystorhinostomy is still the standard procedure complete stenosis of the nasolacrimal duct. New methods try to preserve the natural lacrimal pathway. Song implanted in 1995 a nasolacrimal polyurethane stent through the nasolacrimal duct. The results and complications of this new method are described in this prospective study. METHODS: Thirty consecutive patients with complete obstruction of the nasolacrimal duct or lacrimal sac were included in the study. The stenosis was localized by dacryocystography. The ages ranged from 22 to 87 years (mean, 58.9 +/- 16 years). Dacryocystography was performed immediately, 4 weeks and 8 months after the procedure to verify the position and patency of the stent. RESULTS: Twenty-five short (35 mm) and 5 long (45 mm) stents were implanted. Twenty-four of 30 patients after 4 weeks and 9 of 10 patients after 8 months had reduced or no complaints. In 1 patient the stent was obstructed. Forceful irrigation with saline solution permitted recanalization. In 1 patient the stent had moved into the upper canaliculus. Because of irritation of the canaliculus it had to be pulled out after 2 months. CONCLUSION: The follow-up is still too short to recommend stent implantation as a real alternative to dacryocystorhinostomy. The main advantages are that the procedure is faster, no incision is necessary, and the local anesthesia is easier. The disadvantage is the need for X-ray examination. 相似文献
140.