全文获取类型
收费全文 | 89515篇 |
免费 | 6939篇 |
国内免费 | 215篇 |
专业分类
耳鼻咽喉 | 677篇 |
儿科学 | 2713篇 |
妇产科学 | 1805篇 |
基础医学 | 12363篇 |
口腔科学 | 1824篇 |
临床医学 | 9633篇 |
内科学 | 18853篇 |
皮肤病学 | 1163篇 |
神经病学 | 8172篇 |
特种医学 | 2735篇 |
外国民族医学 | 1篇 |
外科学 | 12550篇 |
综合类 | 1432篇 |
一般理论 | 115篇 |
预防医学 | 8598篇 |
眼科学 | 2027篇 |
药学 | 6237篇 |
1篇 | |
中国医学 | 95篇 |
肿瘤学 | 5675篇 |
出版年
2023年 | 468篇 |
2022年 | 627篇 |
2021年 | 1693篇 |
2020年 | 1028篇 |
2019年 | 1645篇 |
2018年 | 1968篇 |
2017年 | 1488篇 |
2016年 | 1582篇 |
2015年 | 1845篇 |
2014年 | 2753篇 |
2013年 | 3791篇 |
2012年 | 6027篇 |
2011年 | 6252篇 |
2010年 | 3457篇 |
2009年 | 3102篇 |
2008年 | 5600篇 |
2007年 | 6098篇 |
2006年 | 5949篇 |
2005年 | 5724篇 |
2004年 | 5452篇 |
2003年 | 4975篇 |
2002年 | 4833篇 |
2001年 | 1162篇 |
2000年 | 1034篇 |
1999年 | 1174篇 |
1998年 | 1140篇 |
1997年 | 952篇 |
1996年 | 854篇 |
1995年 | 801篇 |
1994年 | 649篇 |
1993年 | 620篇 |
1992年 | 778篇 |
1991年 | 779篇 |
1990年 | 696篇 |
1989年 | 652篇 |
1988年 | 611篇 |
1987年 | 594篇 |
1986年 | 578篇 |
1985年 | 572篇 |
1984年 | 588篇 |
1983年 | 559篇 |
1982年 | 530篇 |
1981年 | 508篇 |
1980年 | 450篇 |
1979年 | 387篇 |
1978年 | 382篇 |
1977年 | 339篇 |
1976年 | 255篇 |
1974年 | 286篇 |
1973年 | 252篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
The clinical effects of concurrent and close temporal administration of electroconvulsive therapy (ECT) and lithium (Li) were investigated by chart review. Three groups of patients were compared on the basis of ECT-related complications, total length of hospital stay (LOS), and post-ECT hospital stay. The groups consisted of patients administered concurrent ECT and Li (n = 27); patients administered Li within 24 h prior to ECT or within 48 h post-ECT (n = 49); and patients administered ECT without concurrent or close temporal administration of Li (n = 100). Prolonged or severe post-ECT confusion was significantly associated with close timing of administration of Li relative to the ECT course. The groups did not differ in the number of complications or the total LOS, although the post-ECT LOS was significantly longer in the group administered Li in close temporal association with ECT. These data suggest that caution should be exercised in the combined use of these treatment modalities. 相似文献
992.
Late-systolic pumping properties of the left ventricle. Deviation from elastance-resistance behavior 总被引:1,自引:0,他引:1
Elastance-resistance [E(t)-R] representations of the left ventricle (LV) were evaluated for their ability to reproduce instantaneous pressure [P(t)] and outflow [Q(t)]. Experiments were performed in open-chest rats. P(t) and Q(t) were measured during steady-state ejecting beats and during a beat in which the aorta was suddenly clamped. The degree of clamping varied from partial to total occlusion. The total occlusion beat was considered an isovolumic beat that generated an isovolumic pressure [Piso(t)] with a characteristic time to maximal Piso(t) [Tpisomax]. In ejecting beats, 34% of stroke volume was delivered after Tpisomax. P(t) and Q(t) from the steady-state ejecting beats and Piso(t) from the clamped beat were then used to estimate parameters of an E(t)-R model. Components of P(t) and Q(t) not accounted for by E(t)-R were identified and termed extra-pressure [Pext(t)] and extra-outflow [Qext(t)]. Pext(t) and Qext(t) were near-zero valued until Tpisomax; then they became systematically positive and finally negative valued after end ejection. During partial aortic occlusion, P(t) was elevated and Q(t) was reduced. However, the time of ejection was extended, and the fraction of stroke volume delivered after Tpisomax increased as P(t) was made higher. Partial occlusion also prolonged the positive phase of Pext(t) and Qext(t). Elements possessing "active" and "deactive" properties were added to the E(t)-R model in an attempt to account for Pext(t) and Qext(t) during partial occlusion. Optional forms of these elements were considered. These expanded E(t)-R models were fitted to basal ejecting data and then asked to predict data from a partial occlusion beat. All expanded models failed to adequately predict the partial occlusion pressure and/or outflow. It was concluded that 1) late ejection was quantitatively important to LV pumping, 2) behavior during late ejection was inconsistent with E(t)-R, and 3) ad hoc modification of E(t)-R models was not likely to yield LV pumping models that could satisfactorily reproduce instantaneous P(t) and Q(t) behavior over the entire ejection period. 相似文献
993.
Andrew D. Medhurst Gerd E. K. Novotny Stephen G. Parker Nicola M. Deighton Alberto J. Kaumann 《Naunyn-Schmiedeberg's archives of pharmacology》1993,347(3):257-265
Summary To investigate whether 5-HT1-like receptor-mediated inhibition of adenosine 3 : 5-cyclic monophosphate (cyclic AMP) accumulation occurs in nerves or smooth muscle of saphenous vein, infusions of 6-hydroxydopamine (6-OHDA) were administered to dogs with the aim of inducing sympathetic nerve damage. The effects of 6-OHDA on other 5-HT1-like receptor-mediated responses at the pre- and post-junctional level were investigated for comparison by studying 5-hydroxytryptamine (5-HT)-induced inhibition of 3H-noradrenaline release and contraction of smooth muscle respectively.Disruption of nerve function by 6-OHDA was revealed by the lack of catecholaminergic fluorescence and neurogenic contractile responses in saphenous veins from dogs treated with 6-OHDA. In addition, severe impairment of neuronal uptake mechanisms were apparent since basal efflux of 3H-noradrenaline, electrically-evoked release of 3H-noradrenaline and remaining 3H-noradrenaline content were considerably reduced. Some 3H-noradrenaline was taken up and released in 6-OHDA treated tissues which is consistent with the existence of nerve varicosities resistant to the present dosing regime of 6-OHDA, an observation substantiated by electron microscopy studies showing inconsistent lesions of nerve terminals.6-OHDA pre-treatment potentiated the smooth muscle contractile responses mediated by 5-HT1-like receptors as well as potentiating 5-HT-evoked inhibition of prostaglandin E2-stimulated cyclic AMP accumulation. It did not, however, affect 5-HT-induced inhibition of 3H-noradrenaline release. The present results suggest that inhibition of cyclic AMP accumulation by 5-HT occurs predominantly in smooth muscle.
Correspondence to A. J. Kaumann at the above address 相似文献
994.
Campbell P 《Health progress (Saint Louis, Mo.)》1993,74(7):54-5, 65
Since the 1970s, the outcomes in antitrust actions against healthcare facilities have become significantly more predictable. But there are still differences of opinion among healthcare providers and antitrust enforcers as to how far antitrust enforcement activities should go. Antitrust enforcement involves a determination of reasonable and unreasonable activities, rather than the application of clear rules. This can lead to confusion over what is legal and may inhibit providers from engaging in collaborative efforts. Intent is very important in antitrust matters. A cooperative venture's effect on the consumer is the primary factor in the enforcers' consideration of whether it is reasonable. Thus well-planned and appropriate healthcare ventures will succeed in most places. Congress has been considering the antitrust implications of healthcare reform. To date, however, there is no consensus on what antitrust laws need changing, if any, or whether new definitions or exemptions could address the problem. Integrated delivery networks (IDNs), the central feature of many healthcare reform proposals, could raise many classic antitrust concerns. Antitrust enforcers' interest in these arrangements will vary according to their effect on competition. Any attempts to establish IDNs will need to also ensure clear language exists regarding the reach of antitrust laws. 相似文献
995.
Bauman Adrian; Antic Ral; Rubinfeld Abe; Zimmerman Paul; Gutch Dick; Bacon Brian; Campbell Helli; Noonan Tony 《Health education research》1993,8(4):581-587
Asthma is a very common chronic illness in Australia; however,unrecognized and undertreated asthma is responsible for muchpreventable morbidity in the community. In 1988, a coalitionof private and public sector agencies was formed to conducta national mass communications program aimed at increasing awarenessabout asthma. This pilot campaign comprised a mailout to allprimary care physicians and a mass media campaign, entitled"Could it be asthma?". The impact of this media-based strategywas assessed using population surveys of 1300 adults beforeand after the campaign. Following the campaign, recall of recentasthma media messages increased from 24 to 49% (P < 0.001)and the proportion who recognized possible asthma symptoms intheir household increased from 3.4 to 5.5% following the campaign.Of those with symptoms, twice as many reported that they visiteda doctor to have their symptoms assessed after the campaign.Knowledge of asthma symptoms was significantly higher followingthe campaign (P < 0.001), after adjustment for age, sex andthe presence of asthma in the respondents family. The campaignappeared to have some success in raising awareness about asthma,and has been followed by the development of a National AsthmaCampaign in Australia focusing on reducing asthma morbidityand improving its management. 相似文献
996.
Total parenteral nutrition during acute pancreatitis: Clinical experience with 156 Patients 总被引:3,自引:0,他引:3
Arnold P. Robin M.D. Rebecca Campbell R.D. Colathur K. Palani M.D. Katherine Liu M.D. Philip E. Donahue M.D. Lloyd M. Nyhus M.D. 《World journal of surgery》1990,14(5):572-579
Over a 3-year period, 156 of 815 patients admitted to a single institution with acute pancreatitis received total parenteral nutrition (TPN) for 2,572 patient days. Seventy had simple acute pancreatitis (group I) and 86 (group II) developed local complex disease (pseudocyst, abscess, or necrotic gland). In groups I and II, respectively, days without oral intake (NPO) were 13.6±1.5 (SEM) and 24.0±2.1 (p<0.005), hospital days were 19.8±1.7 and 35.8±3.2 (p<0.005), and duration of TPN was 10.9 ±1.0 and 21.0±2.3 days (p<0.005). Thirty-three patients in group I and 53 in group II required exogenous insulin. Alteration of standard formulas was necessary in 87 patients, but cessation of therapy was necessary in only one instance. Twenty catheters were removed for suspected sepsis with only 3 confirmed cases. Fat-based formulas were well tolerated in 15% of patients. During TPN, body weight rose from 95.0±2.4% to 97.4±4.3% of ideal in group I and remained at 90.5±1.8% in group II. Albumin rose from 3.36±0.10 to 3.50±0.08 g/dl in group I and from 3.01±0.07 to 3.35±0.07 g/dl in group II. The entire cohort differed from 10 randomly chosen patients who did not receive TPN in terms of days NPO (2.8±0.3) and hospital days (5.5±0.6). Variables associated with prolongation of hospital stay and time NPO were number of prognostic criteria, local complex disease, and underlying chronic pancreatitis only in select groups. We conclude that during acute pancreatitis, TPN can be administered safely but with careful monitoring and we recommend early aggressive therapy in the subgroups noted above and when underlying malnutrition exists. In the borderline patient, TPN may be administered by peripheral vein until the severity of disease is manifest.
Presented at the Société Internationale de Chirurgie in Toronto, Ontario, Canada, September, 1989. 相似文献
Resumen En el curso de un período de 3 años, 156 de 815 pacientes hospitalizados en una sola institución por pancreatitis aguda recibieron nutrición parenteral total (NPT) durante 2,572 paciente-días. Setenta presentaban pancreatitis aguda simple (grupo I) y 86 (grupo II) desarrollaron enfermedad local complicada (pseudoquiste, absceso, o necrosis de la glándula). Las siguientes fueron las características de los grupos I y II, respectivamente: días sin ingesta oral (NPO) 13.6±1.5 (SEM) y 24.0±2.1 (p<0.005), días de hospitalización: 19.8±1.7 y 35.8±3.2 (p<0.005), y duración de la NPT: 10.9±1.0 y 21.0 ±2.3 días (p<0.005). Trienta y tres pacientes en el grupo I y 53 en el grupo II requirieron insulina exógena. Se requirió alterar la fórmula estándar en 87 pacientes, pero sólo fue necesario cesar la terapia en un caso. Veinte catéteres fueron retirados por sospecha de sepsis, pero sólo en 3 se confirmó. Las fórmulas a base de grasa fueron bien toleradas en 15% de los pacientes. En el curso de la NPT el peso corporal ascendió de 95.0±2.4% a 97.4±4.3% del peso ideal en el grupo I y se mantuvo a un 90.5±1.8% en el grupo II. La albúmina ascendió de 3.36±0.10 a 3.50±0.8 g/dl en el grupo I y de 3.01±0.07 a 3.35±0.07 g/dl en el grupo II. Toda la cohorte se diferenció de un grupo de 10 pacientes escogidos al azar que no recibieron NPT en términos del número de días NPO (2.8±0.3) y de días de hospitalización (5.5±0.6). Las variables que aparecieron asociadas con prolongación de la hospitalización y el tiempo NPO fueron el número de criterios de pronóstico, la enfermedad complicada, y la presencia de pancreatitis crónica subyacente sólo en grupos seleccionados. Nuestra conclusión es que en el curso de la pancreatitis aguda, la NPT puede ser administrada con seguridad pero bajo monitoría cuidadosa, y recomendamos terapia agresiva precoz en los subgrupos anotados anteriormente y cuando exista mal nutrición concomitante. En el paciente limitrofe se puede administrar la NPT por vía periférica hasta cuando la gravedad de la enfermedad se haga manifiesta.
Résumé Pendant une période de 3 ans, 156 des 815 patients admis pour pancréatite aiguë ont reçu une alimentation parentérale totale (APT), soit en tout 2,572 jours patient. Soixante dix patients (groupe I) avaient une pancréatite simple et 86 (groupe II) avaient aussi une maladie locale complexe (pseudokyste, abcès ou nécrose du pancréas). La durée du jeûne était respectivement de 13.6±1.5 (ET) et de 24.0±2.1 (p<0.005), la durée moyenne de séjour était respectivement de 19.8±1.7 et de 35.8 ±3.2 (p<0.005) alors que la durée d'APT était respectivement de 10.9±1.0 et de 21.0±2.3 jours (p<0.005). Trente-trois patients dans le groupe I et 53 dans le groupe II avaient besoin d'insuline exogène. Un changement dans la formule standard a été nécessaire chez 87 patients mais l'APT n'a du être arrêté complètement que chez un patient seul. Vingt cathéters ont été enlevés avec suspicion de sepsis, confirmée cependant dans 3 cas seulement. Les compositions à base de lipides ont été bien tolérées chez 15% des patients. Pendant l'APT, le poids du corps s'est élevé de 95.0±2.4% à 97.4±4.3% du poids idéal chez les patients du groupe I et est resté à 90.5±1.8% chez ceux du groupe II. L'albumine s'est élevée de 3.36±0.10 à 3.50 ±0.08 g/dl dans le groupe I et de 3.01±0.07 à 3.35±0.07 g/dl dans le groupe II. La durée du jeûne (2.8±0.3) et la durée moyenne de séjour (5.5±0.6) de l'ensemble des patients différaient de ces mêmes données chez 10 autres patients choisis au hasard. Les facteurs associés avec un séjour hospitalier prolongé et sans alimentation orale étaient le nombre de critères pronostiques, l'existence de complications locales, et de pancréatite chronique sous-jacente chez certains patients. Nous concluons que pendant la pancréatite aiguë, l'APT peut être administrée sans danger sous contrôle permanent et nous conseillons un traitement agressif et précoce dans le sous groupe mentionné plus haut ou quand existe un état de nutrition déficient. Chez le patient limite, on peut se contenter d'APT par une veine périphérique tant que des signes de gravité ne se manifestent pas.
Presented at the Société Internationale de Chirurgie in Toronto, Ontario, Canada, September, 1989. 相似文献
997.
Interactive videodisks are state-of-the-art technology, and their potential is rapidly beginning to be recognized in the health care industry. A recent survey of 169 health institutions found that 79% planned the purchase of videodisks within the next year, and 72% planned to develop a videodisk program. As the role of the medical records practitioner increasingly includes acting as a hospitalwide information manager, CAVI provides the medical records professional a unique opportunity to both provide effective training within the department and hospital and be the leader in bringing the advantages of CAVI to the institution. 相似文献
998.
Campbell V 《Topics in health record management》1990,10(4):1-8
PLM will have a significant impact on an organization's mission, management philosophy, marketing plan, and most definitely, day-to-day operations. PLM offers an alternative to traditional management approaches for the medical record department and the health care industry as a whole. The medical record professional should understand PLM both as a hospital wide structure and as an internal structure used to maximize departmental productivity and use of resources. 相似文献
999.
The evolution of care for AIDS patients at the Chikankata Hospital in Southern Zambia, from inpatient to outpatient management, is described. Hospital and community health care of AIDs patients should integrate education, counseling, clinical, nursing, laboratory, pastoral care and administration. Decentralization of primary health car into the wider community is achieved in this way. The ultimate result of community care is re-education of the family and the community so that behavioral change in patterns of sexual intercourse occurs. At Chikankata Hospital the average length of stay of HIV patients has fallen from 32 days in 1987 to 16.2 days in 1988. Numbers of home care patients have increased, as 80% prefer home visits, and most people prefer to die at home. As an example of the powerful effect of community counseling as a result of home care, people are deciding to take action on the issue of ritual cleansing by sexual intercourse, to re-introduce traditional taboos and family authority, and to discuss the effect of alcohol on AIDS. Chikankata Hospital has also started training programs for AIDS health workers from the region, and for local volunteers. Transferable management concepts include the term "normalization" which implies that AIDS is here to stay and future generations must be protected by permanent change in behavior. 相似文献
1000.
趋化因子SDF-1β在大肠杆菌中的表达及其纯化 总被引:6,自引:2,他引:4
目的 重组人SDF 1 β在大肠杆菌中表达并获得纯化的有生物学活性的SDF 1 β蛋白。 方法 以pET32a( + ) SDF 1为人SDF 1 β克隆基因的表达载体 ,以大肠杆菌AD494(DE3)pLysS为表达菌 ,在IPTG诱导下表达出一个由 2 30个氨基酸残基组成的硫氧还蛋白 (thioredoxin) SDF 1 β的融合蛋白 ( 2 6× 1 0 3)。经细菌裂解、金属离子螯合亲和层析、肠激酶消化以游离SDF 1 β、阳离子交换层析和逆向高效液相层析等步骤纯化目的蛋白。以蛋白印迹、纯化产物的N端氨基酸测序及配体结合试验、微生理监测术鉴定纯化产物的生化性质及生物学活性。结果 在经诱导的发酵菌中融合蛋白占总菌体蛋白的 1 0 %~ 1 5 %。从 1L发酵菌液中可获得高纯度目的蛋白约 40 0 μg。蛋白印迹实验及N端氨基酸测序皆证实纯化终产物为SDF 1 β(由 71个氨基酸残基组成 ,7.8× 1 0 3)。配体结合试验及Cytosensor表明 ,该产物能与CXCR4结合 [Kd =( 1 2 .2 0± 2 .99)nmol L]并引起CXCR4表达细胞的信号传导。结论 采用本方法可获得高表达的 ,高纯度的具有与天然SDF 1 β相似活性的重组人SDF 1 β。 相似文献